Merge pull request #2721 from TheBlueMatt/2023-11-log-forward-peer

[rust-lightning] / lightning / src / ln / channelmanager.rs

// This file is Copyright its original authors, visible in version control
// history.
//
// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.

//! The top-level channel management and payment tracking stuff lives here.
//!
//! The [`ChannelManager`] is the main chunk of logic implementing the lightning protocol and is
//! responsible for tracking which channels are open, HTLCs are in flight and reestablishing those
//! upon reconnect to the relevant peer(s).
//!
//! It does not manage routing logic (see [`Router`] for that) nor does it manage constructing
//! on-chain transactions (it only monitors the chain to watch for any force-closes that might
//! imply it needs to fail HTLCs/payments/channels it manages).

use bitcoin::blockdata::block::Header;
use bitcoin::blockdata::transaction::Transaction;
use bitcoin::blockdata::constants::ChainHash;
use bitcoin::key::constants::SECRET_KEY_SIZE;
use bitcoin::network::constants::Network;

use bitcoin::hashes::Hash;
use bitcoin::hashes::sha256::Hash as Sha256;
use bitcoin::hash_types::{BlockHash, Txid};

use bitcoin::secp256k1::{SecretKey,PublicKey};
use bitcoin::secp256k1::Secp256k1;
use bitcoin::{secp256k1, Sequence};

use crate::blinded_path::BlindedPath;
use crate::blinded_path::payment::{PaymentConstraints, ReceiveTlvs};
use crate::chain;
use crate::chain::{Confirm, ChannelMonitorUpdateStatus, Watch, BestBlock};
use crate::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator, LowerBoundedFeeEstimator};
use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, HTLC_FAIL_BACK_BUFFER, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY, MonitorEvent, CLOSED_CHANNEL_UPDATE_ID};
use crate::chain::transaction::{OutPoint, TransactionData};
use crate::events;
use crate::events::{Event, EventHandler, EventsProvider, MessageSendEvent, MessageSendEventsProvider, ClosureReason, HTLCDestination, PaymentFailureReason};
// Since this struct is returned in `list_channels` methods, expose it here in case users want to
// construct one themselves.
use crate::ln::{inbound_payment, ChannelId, PaymentHash, PaymentPreimage, PaymentSecret};
use crate::ln::channel::{Channel, ChannelPhase, ChannelContext, ChannelError, ChannelUpdateStatus, ShutdownResult, UnfundedChannelContext, UpdateFulfillCommitFetch, OutboundV1Channel, InboundV1Channel};
use crate::ln::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
#[cfg(any(feature = "_test_utils", test))]
use crate::ln::features::Bolt11InvoiceFeatures;
use crate::routing::gossip::NetworkGraph;
use crate::routing::router::{BlindedTail, DefaultRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::routing::scoring::{ProbabilisticScorer, ProbabilisticScoringFeeParameters};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::HTLCFailReason;
use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError};
#[cfg(test)]
use crate::ln::outbound_payment;
use crate::ln::outbound_payment::{Bolt12PaymentError, OutboundPayments, PaymentAttempts, PendingOutboundPayment, SendAlongPathArgs, StaleExpiration};
use crate::ln::wire::Encode;
use crate::offers::invoice::{BlindedPayInfo, Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, DerivedSigningPubkey, InvoiceBuilder};
use crate::offers::invoice_error::InvoiceError;
use crate::offers::merkle::SignError;
use crate::offers::offer::{DerivedMetadata, Offer, OfferBuilder};
use crate::offers::parse::Bolt12SemanticError;
use crate::offers::refund::{Refund, RefundBuilder};
use crate::onion_message::{Destination, OffersMessage, OffersMessageHandler, PendingOnionMessage, new_pending_onion_message};
use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient, SignerProvider};
use crate::sign::ecdsa::WriteableEcdsaChannelSigner;
use crate::util::config::{UserConfig, ChannelConfig, ChannelConfigUpdate};
use crate::util::wakers::{Future, Notifier};
use crate::util::scid_utils::fake_scid;
use crate::util::string::UntrustedString;
use crate::util::ser::{BigSize, FixedLengthReader, Readable, ReadableArgs, MaybeReadable, Writeable, Writer, VecWriter};
use crate::util::logger::{Level, Logger};
use crate::util::errors::APIError;

use alloc::collections::{btree_map, BTreeMap};

use crate::io;
use crate::prelude::*;
use core::{cmp, mem};
use core::cell::RefCell;
use crate::io::Read;
use crate::sync::{Arc, Mutex, RwLock, RwLockReadGuard, FairRwLock, LockTestExt, LockHeldState};
use core::sync::atomic::{AtomicUsize, AtomicBool, Ordering};
use core::time::Duration;
use core::ops::Deref;

// Re-export this for use in the public API.
pub use crate::ln::outbound_payment::{PaymentSendFailure, ProbeSendFailure, Retry, RetryableSendFailure, RecipientOnionFields};
use crate::ln::script::ShutdownScript;

// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
// forward the HTLC with information it will give back to us when it does so, or if it should Fail
// the HTLC with the relevant message for the Channel to handle giving to the remote peer.
//
// Once said HTLC is committed in the Channel, if the PendingHTLCStatus indicated Forward, the
// Channel will return the PendingHTLCInfo back to us, and we will create an HTLCForwardInfo
// with it to track where it came from (in case of onwards-forward error), waiting a random delay
// before we forward it.
//
// We will then use HTLCForwardInfo's PendingHTLCInfo to construct an outbound HTLC, with a
// relevant HTLCSource::PreviousHopData filled in to indicate where it came from (which we can use
// to either fail-backwards or fulfill the HTLC backwards along the relevant path).
// Alternatively, we can fill an outbound HTLC with a HTLCSource::OutboundRoute indicating this is
// our payment, which we can use to decode errors or inform the user that the payment was sent.

/// Routing info for an inbound HTLC onion.
#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub enum PendingHTLCRouting {
        /// A forwarded HTLC.
        Forward {
                /// BOLT 4 onion packet.
                onion_packet: msgs::OnionPacket,
                /// The SCID from the onion that we should forward to. This could be a real SCID or a fake one
                /// generated using `get_fake_scid` from the scid_utils::fake_scid module.
                short_channel_id: u64, // This should be NonZero<u64> eventually when we bump MSRV
        },
        /// An HTLC paid to an invoice we generated.
        Receive {
                /// Payment secret and total msat received.
                payment_data: msgs::FinalOnionHopData,
                /// See [`RecipientOnionFields::payment_metadata`] for more info.
                payment_metadata: Option<Vec<u8>>,
                /// Used to track when we should expire pending HTLCs that go unclaimed.
                incoming_cltv_expiry: u32,
                /// Optional shared secret for phantom node.
                phantom_shared_secret: Option<[u8; 32]>,
                /// See [`RecipientOnionFields::custom_tlvs`] for more info.
                custom_tlvs: Vec<(u64, Vec<u8>)>,
        },
        /// Incoming keysend (sender provided the preimage in a TLV).
        ReceiveKeysend {
                /// This was added in 0.0.116 and will break deserialization on downgrades.
                payment_data: Option<msgs::FinalOnionHopData>,
                /// Preimage for this onion payment.
                payment_preimage: PaymentPreimage,
                /// See [`RecipientOnionFields::payment_metadata`] for more info.
                payment_metadata: Option<Vec<u8>>,
                /// CLTV expiry of the incoming HTLC.
                incoming_cltv_expiry: u32, // Used to track when we should expire pending HTLCs that go unclaimed
                /// See [`RecipientOnionFields::custom_tlvs`] for more info.
                custom_tlvs: Vec<(u64, Vec<u8>)>,
        },
}

/// Full details of an incoming HTLC, including routing info.
#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub struct PendingHTLCInfo {
        /// Further routing details based on whether the HTLC is being forwarded or received.
        pub routing: PendingHTLCRouting,
        /// Shared secret from the previous hop.
        pub incoming_shared_secret: [u8; 32],
        payment_hash: PaymentHash,
        /// Amount received
        pub incoming_amt_msat: Option<u64>, // Added in 0.0.113
        /// Sender intended amount to forward or receive (actual amount received
        /// may overshoot this in either case)
        pub outgoing_amt_msat: u64,
        /// Outgoing CLTV height.
        pub outgoing_cltv_value: u32,
        /// The fee being skimmed off the top of this HTLC. If this is a forward, it'll be the fee we are
        /// skimming. If we're receiving this HTLC, it's the fee that our counterparty skimmed.
        pub skimmed_fee_msat: Option<u64>,
}

#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub(super) enum HTLCFailureMsg {
        Relay(msgs::UpdateFailHTLC),
        Malformed(msgs::UpdateFailMalformedHTLC),
}

/// Stores whether we can't forward an HTLC or relevant forwarding info
#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub(super) enum PendingHTLCStatus {
        Forward(PendingHTLCInfo),
        Fail(HTLCFailureMsg),
}

pub(super) struct PendingAddHTLCInfo {
        pub(super) forward_info: PendingHTLCInfo,

        // These fields are produced in `forward_htlcs()` and consumed in
        // `process_pending_htlc_forwards()` for constructing the
        // `HTLCSource::PreviousHopData` for failed and forwarded
        // HTLCs.
        //
        // Note that this may be an outbound SCID alias for the associated channel.
        prev_short_channel_id: u64,
        prev_htlc_id: u64,
        prev_funding_outpoint: OutPoint,
        prev_user_channel_id: u128,
}

pub(super) enum HTLCForwardInfo {
        AddHTLC(PendingAddHTLCInfo),
        FailHTLC {
                htlc_id: u64,
                err_packet: msgs::OnionErrorPacket,
        },
}

/// Tracks the inbound corresponding to an outbound HTLC
#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub(crate) struct HTLCPreviousHopData {
        // Note that this may be an outbound SCID alias for the associated channel.
        short_channel_id: u64,
        user_channel_id: Option<u128>,
        htlc_id: u64,
        incoming_packet_shared_secret: [u8; 32],
        phantom_shared_secret: Option<[u8; 32]>,

        // This field is consumed by `claim_funds_from_hop()` when updating a force-closed backwards
        // channel with a preimage provided by the forward channel.
        outpoint: OutPoint,
}

enum OnionPayload {
        /// Indicates this incoming onion payload is for the purpose of paying an invoice.
        Invoice {
                /// This is only here for backwards-compatibility in serialization, in the future it can be
                /// removed, breaking clients running 0.0.106 and earlier.
                _legacy_hop_data: Option<msgs::FinalOnionHopData>,
        },
        /// Contains the payer-provided preimage.
        Spontaneous(PaymentPreimage),
}

/// HTLCs that are to us and can be failed/claimed by the user
struct ClaimableHTLC {
        prev_hop: HTLCPreviousHopData,
        cltv_expiry: u32,
        /// The amount (in msats) of this MPP part
        value: u64,
        /// The amount (in msats) that the sender intended to be sent in this MPP
        /// part (used for validating total MPP amount)
        sender_intended_value: u64,
        onion_payload: OnionPayload,
        timer_ticks: u8,
        /// The total value received for a payment (sum of all MPP parts if the payment is a MPP).
        /// Gets set to the amount reported when pushing [`Event::PaymentClaimable`].
        total_value_received: Option<u64>,
        /// The sender intended sum total of all MPP parts specified in the onion
        total_msat: u64,
        /// The extra fee our counterparty skimmed off the top of this HTLC.
        counterparty_skimmed_fee_msat: Option<u64>,
}

impl From<&ClaimableHTLC> for events::ClaimedHTLC {
        fn from(val: &ClaimableHTLC) -> Self {
                events::ClaimedHTLC {
                        channel_id: val.prev_hop.outpoint.to_channel_id(),
                        user_channel_id: val.prev_hop.user_channel_id.unwrap_or(0),
                        cltv_expiry: val.cltv_expiry,
                        value_msat: val.value,
                        counterparty_skimmed_fee_msat: val.counterparty_skimmed_fee_msat.unwrap_or(0),
                }
        }
}

/// A user-provided identifier in [`ChannelManager::send_payment`] used to uniquely identify
/// a payment and ensure idempotency in LDK.
///
/// This is not exported to bindings users as we just use [u8; 32] directly
#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
pub struct PaymentId(pub [u8; Self::LENGTH]);

impl PaymentId {
        /// Number of bytes in the id.
        pub const LENGTH: usize = 32;
}

impl Writeable for PaymentId {
        fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
                self.0.write(w)
        }
}

impl Readable for PaymentId {
        fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
                let buf: [u8; 32] = Readable::read(r)?;
                Ok(PaymentId(buf))
        }
}

impl core::fmt::Display for PaymentId {
        fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
                crate::util::logger::DebugBytes(&self.0).fmt(f)
        }
}

/// An identifier used to uniquely identify an intercepted HTLC to LDK.
///
/// This is not exported to bindings users as we just use [u8; 32] directly
#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
pub struct InterceptId(pub [u8; 32]);

impl Writeable for InterceptId {
        fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
                self.0.write(w)
        }
}

impl Readable for InterceptId {
        fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
                let buf: [u8; 32] = Readable::read(r)?;
                Ok(InterceptId(buf))
        }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
/// Uniquely describes an HTLC by its source. Just the guaranteed-unique subset of [`HTLCSource`].
pub(crate) enum SentHTLCId {
        PreviousHopData { short_channel_id: u64, htlc_id: u64 },
        OutboundRoute { session_priv: [u8; SECRET_KEY_SIZE] },
}
impl SentHTLCId {
        pub(crate) fn from_source(source: &HTLCSource) -> Self {
                match source {
                        HTLCSource::PreviousHopData(hop_data) => Self::PreviousHopData {
                                short_channel_id: hop_data.short_channel_id,
                                htlc_id: hop_data.htlc_id,
                        },
                        HTLCSource::OutboundRoute { session_priv, .. } =>
                                Self::OutboundRoute { session_priv: session_priv.secret_bytes() },
                }
        }
}
impl_writeable_tlv_based_enum!(SentHTLCId,
        (0, PreviousHopData) => {
                (0, short_channel_id, required),
                (2, htlc_id, required),
        },
        (2, OutboundRoute) => {
                (0, session_priv, required),
        };
);


/// Tracks the inbound corresponding to an outbound HTLC
#[allow(clippy::derive_hash_xor_eq)] // Our Hash is faithful to the data, we just don't have SecretKey::hash
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) enum HTLCSource {
        PreviousHopData(HTLCPreviousHopData),
        OutboundRoute {
                path: Path,
                session_priv: SecretKey,
                /// Technically we can recalculate this from the route, but we cache it here to avoid
                /// doing a double-pass on route when we get a failure back
                first_hop_htlc_msat: u64,
                payment_id: PaymentId,
        },
}
#[allow(clippy::derive_hash_xor_eq)] // Our Hash is faithful to the data, we just don't have SecretKey::hash
impl core::hash::Hash for HTLCSource {
        fn hash<H: core::hash::Hasher>(&self, hasher: &mut H) {
                match self {
                        HTLCSource::PreviousHopData(prev_hop_data) => {
                                0u8.hash(hasher);
                                prev_hop_data.hash(hasher);
                        },
                        HTLCSource::OutboundRoute { path, session_priv, payment_id, first_hop_htlc_msat } => {
                                1u8.hash(hasher);
                                path.hash(hasher);
                                session_priv[..].hash(hasher);
                                payment_id.hash(hasher);
                                first_hop_htlc_msat.hash(hasher);
                        },
                }
        }
}
impl HTLCSource {
        #[cfg(all(feature = "_test_vectors", not(feature = "grind_signatures")))]
        #[cfg(test)]
        pub fn dummy() -> Self {
                HTLCSource::OutboundRoute {
                        path: Path { hops: Vec::new(), blinded_tail: None },
                        session_priv: SecretKey::from_slice(&[1; 32]).unwrap(),
                        first_hop_htlc_msat: 0,
                        payment_id: PaymentId([2; 32]),
                }
        }

        #[cfg(debug_assertions)]
        /// Checks whether this HTLCSource could possibly match the given HTLC output in a commitment
        /// transaction. Useful to ensure different datastructures match up.
        pub(crate) fn possibly_matches_output(&self, htlc: &super::chan_utils::HTLCOutputInCommitment) -> bool {
                if let HTLCSource::OutboundRoute { first_hop_htlc_msat, .. } = self {
                        *first_hop_htlc_msat == htlc.amount_msat
                } else {
                        // There's nothing we can check for forwarded HTLCs
                        true
                }
        }
}

/// Invalid inbound onion payment.
pub struct InboundOnionErr {
        /// BOLT 4 error code.
        pub err_code: u16,
        /// Data attached to this error.
        pub err_data: Vec<u8>,
        /// Error message text.
        pub msg: &'static str,
}

/// This enum is used to specify which error data to send to peers when failing back an HTLC
/// using [`ChannelManager::fail_htlc_backwards_with_reason`].
///
/// For more info on failure codes, see <https://github.com/lightning/bolts/blob/master/04-onion-routing.md#failure-messages>.
#[derive(Clone, Copy)]
pub enum FailureCode {
        /// We had a temporary error processing the payment. Useful if no other error codes fit
        /// and you want to indicate that the payer may want to retry.
        TemporaryNodeFailure,
        /// We have a required feature which was not in this onion. For example, you may require
        /// some additional metadata that was not provided with this payment.
        RequiredNodeFeatureMissing,
        /// You may wish to use this when a `payment_preimage` is unknown, or the CLTV expiry of
        /// the HTLC is too close to the current block height for safe handling.
        /// Using this failure code in [`ChannelManager::fail_htlc_backwards_with_reason`] is
        /// equivalent to calling [`ChannelManager::fail_htlc_backwards`].
        IncorrectOrUnknownPaymentDetails,
        /// We failed to process the payload after the onion was decrypted. You may wish to
        /// use this when receiving custom HTLC TLVs with even type numbers that you don't recognize.
        ///
        /// If available, the tuple data may include the type number and byte offset in the
        /// decrypted byte stream where the failure occurred.
        InvalidOnionPayload(Option<(u64, u16)>),
}

impl Into<u16> for FailureCode {
    fn into(self) -> u16 {
                match self {
                        FailureCode::TemporaryNodeFailure => 0x2000 | 2,
                        FailureCode::RequiredNodeFeatureMissing => 0x4000 | 0x2000 | 3,
                        FailureCode::IncorrectOrUnknownPaymentDetails => 0x4000 | 15,
                        FailureCode::InvalidOnionPayload(_) => 0x4000 | 22,
                }
        }
}

/// Error type returned across the peer_state mutex boundary. When an Err is generated for a
/// Channel, we generally end up with a ChannelError::Close for which we have to close the channel
/// immediately (ie with no further calls on it made). Thus, this step happens inside a
/// peer_state lock. We then return the set of things that need to be done outside the lock in
/// this struct and call handle_error!() on it.

struct MsgHandleErrInternal {
        err: msgs::LightningError,
        chan_id: Option<(ChannelId, u128)>, // If Some a channel of ours has been closed
        shutdown_finish: Option<(ShutdownResult, Option<msgs::ChannelUpdate>)>,
        channel_capacity: Option<u64>,
}
impl MsgHandleErrInternal {
        #[inline]
        fn send_err_msg_no_close(err: String, channel_id: ChannelId) -> Self {
                Self {
                        err: LightningError {
                                err: err.clone(),
                                action: msgs::ErrorAction::SendErrorMessage {
                                        msg: msgs::ErrorMessage {
                                                channel_id,
                                                data: err
                                        },
                                },
                        },
                        chan_id: None,
                        shutdown_finish: None,
                        channel_capacity: None,
                }
        }
        #[inline]
        fn from_no_close(err: msgs::LightningError) -> Self {
                Self { err, chan_id: None, shutdown_finish: None, channel_capacity: None }
        }
        #[inline]
        fn from_finish_shutdown(err: String, channel_id: ChannelId, user_channel_id: u128, shutdown_res: ShutdownResult, channel_update: Option<msgs::ChannelUpdate>, channel_capacity: u64) -> Self {
                let err_msg = msgs::ErrorMessage { channel_id, data: err.clone() };
                let action = if shutdown_res.monitor_update.is_some() {
                        // We have a closing `ChannelMonitorUpdate`, which means the channel was funded and we
                        // should disconnect our peer such that we force them to broadcast their latest
                        // commitment upon reconnecting.
                        msgs::ErrorAction::DisconnectPeer { msg: Some(err_msg) }
                } else {
                        msgs::ErrorAction::SendErrorMessage { msg: err_msg }
                };
                Self {
                        err: LightningError { err, action },
                        chan_id: Some((channel_id, user_channel_id)),
                        shutdown_finish: Some((shutdown_res, channel_update)),
                        channel_capacity: Some(channel_capacity)
                }
        }
        #[inline]
        fn from_chan_no_close(err: ChannelError, channel_id: ChannelId) -> Self {
                Self {
                        err: match err {
                                ChannelError::Warn(msg) =>  LightningError {
                                        err: msg.clone(),
                                        action: msgs::ErrorAction::SendWarningMessage {
                                                msg: msgs::WarningMessage {
                                                        channel_id,
                                                        data: msg
                                                },
                                                log_level: Level::Warn,
                                        },
                                },
                                ChannelError::Ignore(msg) => LightningError {
                                        err: msg,
                                        action: msgs::ErrorAction::IgnoreError,
                                },
                                ChannelError::Close(msg) => LightningError {
                                        err: msg.clone(),
                                        action: msgs::ErrorAction::SendErrorMessage {
                                                msg: msgs::ErrorMessage {
                                                        channel_id,
                                                        data: msg
                                                },
                                        },
                                },
                        },
                        chan_id: None,
                        shutdown_finish: None,
                        channel_capacity: None,
                }
        }

        fn closes_channel(&self) -> bool {
                self.chan_id.is_some()
        }
}

/// We hold back HTLCs we intend to relay for a random interval greater than this (see
/// Event::PendingHTLCsForwardable for the API guidelines indicating how long should be waited).
/// This provides some limited amount of privacy. Ideally this would range from somewhere like one
/// second to 30 seconds, but people expect lightning to be, you know, kinda fast, sadly.
pub(super) const MIN_HTLC_RELAY_HOLDING_CELL_MILLIS: u64 = 100;

/// For events which result in both a RevokeAndACK and a CommitmentUpdate, by default they should
/// be sent in the order they appear in the return value, however sometimes the order needs to be
/// variable at runtime (eg Channel::channel_reestablish needs to re-send messages in the order
/// they were originally sent). In those cases, this enum is also returned.
#[derive(Clone, PartialEq)]
pub(super) enum RAACommitmentOrder {
        /// Send the CommitmentUpdate messages first
        CommitmentFirst,
        /// Send the RevokeAndACK message first
        RevokeAndACKFirst,
}

/// Information about a payment which is currently being claimed.
struct ClaimingPayment {
        amount_msat: u64,
        payment_purpose: events::PaymentPurpose,
        receiver_node_id: PublicKey,
        htlcs: Vec<events::ClaimedHTLC>,
        sender_intended_value: Option<u64>,
}
impl_writeable_tlv_based!(ClaimingPayment, {
        (0, amount_msat, required),
        (2, payment_purpose, required),
        (4, receiver_node_id, required),
        (5, htlcs, optional_vec),
        (7, sender_intended_value, option),
});

struct ClaimablePayment {
        purpose: events::PaymentPurpose,
        onion_fields: Option<RecipientOnionFields>,
        htlcs: Vec<ClaimableHTLC>,
}

/// Information about claimable or being-claimed payments
struct ClaimablePayments {
        /// Map from payment hash to the payment data and any HTLCs which are to us and can be
        /// failed/claimed by the user.
        ///
        /// Note that, no consistency guarantees are made about the channels given here actually
        /// existing anymore by the time you go to read them!
        ///
        /// When adding to the map, [`Self::pending_claiming_payments`] must also be checked to ensure
        /// we don't get a duplicate payment.
        claimable_payments: HashMap<PaymentHash, ClaimablePayment>,

        /// Map from payment hash to the payment data for HTLCs which we have begun claiming, but which
        /// are waiting on a [`ChannelMonitorUpdate`] to complete in order to be surfaced to the user
        /// as an [`events::Event::PaymentClaimed`].
        pending_claiming_payments: HashMap<PaymentHash, ClaimingPayment>,
}

/// Events which we process internally but cannot be processed immediately at the generation site
/// usually because we're running pre-full-init. They are handled immediately once we detect we are
/// running normally, and specifically must be processed before any other non-background
/// [`ChannelMonitorUpdate`]s are applied.
#[derive(Debug)]
enum BackgroundEvent {
        /// Handle a ChannelMonitorUpdate which closes the channel or for an already-closed channel.
        /// This is only separated from [`Self::MonitorUpdateRegeneratedOnStartup`] as the
        /// maybe-non-closing variant needs a public key to handle channel resumption, whereas if the
        /// channel has been force-closed we do not need the counterparty node_id.
        ///
        /// Note that any such events are lost on shutdown, so in general they must be updates which
        /// are regenerated on startup.
        ClosedMonitorUpdateRegeneratedOnStartup((OutPoint, ChannelMonitorUpdate)),
        /// Handle a ChannelMonitorUpdate which may or may not close the channel and may unblock the
        /// channel to continue normal operation.
        ///
        /// In general this should be used rather than
        /// [`Self::ClosedMonitorUpdateRegeneratedOnStartup`], however in cases where the
        /// `counterparty_node_id` is not available as the channel has closed from a [`ChannelMonitor`]
        /// error the other variant is acceptable.
        ///
        /// Note that any such events are lost on shutdown, so in general they must be updates which
        /// are regenerated on startup.
        MonitorUpdateRegeneratedOnStartup {
                counterparty_node_id: PublicKey,
                funding_txo: OutPoint,
                update: ChannelMonitorUpdate
        },
        /// Some [`ChannelMonitorUpdate`] (s) completed before we were serialized but we still have
        /// them marked pending, thus we need to run any [`MonitorUpdateCompletionAction`] (s) pending
        /// on a channel.
        MonitorUpdatesComplete {
                counterparty_node_id: PublicKey,
                channel_id: ChannelId,
        },
}

#[derive(Debug)]
pub(crate) enum MonitorUpdateCompletionAction {
        /// Indicates that a payment ultimately destined for us was claimed and we should emit an
        /// [`events::Event::PaymentClaimed`] to the user if we haven't yet generated such an event for
        /// this payment. Note that this is only best-effort. On restart it's possible such a duplicate
        /// event can be generated.
        PaymentClaimed { payment_hash: PaymentHash },
        /// Indicates an [`events::Event`] should be surfaced to the user and possibly resume the
        /// operation of another channel.
        ///
        /// This is usually generated when we've forwarded an HTLC and want to block the outbound edge
        /// from completing a monitor update which removes the payment preimage until the inbound edge
        /// completes a monitor update containing the payment preimage. In that case, after the inbound
        /// edge completes, we will surface an [`Event::PaymentForwarded`] as well as unblock the
        /// outbound edge.
        EmitEventAndFreeOtherChannel {
                event: events::Event,
                downstream_counterparty_and_funding_outpoint: Option<(PublicKey, OutPoint, RAAMonitorUpdateBlockingAction)>,
        },
        /// Indicates we should immediately resume the operation of another channel, unless there is
        /// some other reason why the channel is blocked. In practice this simply means immediately
        /// removing the [`RAAMonitorUpdateBlockingAction`] provided from the blocking set.
        ///
        /// This is usually generated when we've forwarded an HTLC and want to block the outbound edge
        /// from completing a monitor update which removes the payment preimage until the inbound edge
        /// completes a monitor update containing the payment preimage. However, we use this variant
        /// instead of [`Self::EmitEventAndFreeOtherChannel`] when we discover that the claim was in
        /// fact duplicative and we simply want to resume the outbound edge channel immediately.
        ///
        /// This variant should thus never be written to disk, as it is processed inline rather than
        /// stored for later processing.
        FreeOtherChannelImmediately {
                downstream_counterparty_node_id: PublicKey,
                downstream_funding_outpoint: OutPoint,
                blocking_action: RAAMonitorUpdateBlockingAction,
        },
}

impl_writeable_tlv_based_enum_upgradable!(MonitorUpdateCompletionAction,
        (0, PaymentClaimed) => { (0, payment_hash, required) },
        // Note that FreeOtherChannelImmediately should never be written - we were supposed to free
        // *immediately*. However, for simplicity we implement read/write here.
        (1, FreeOtherChannelImmediately) => {
                (0, downstream_counterparty_node_id, required),
                (2, downstream_funding_outpoint, required),
                (4, blocking_action, required),
        },
        (2, EmitEventAndFreeOtherChannel) => {
                (0, event, upgradable_required),
                // LDK prior to 0.0.116 did not have this field as the monitor update application order was
                // required by clients. If we downgrade to something prior to 0.0.116 this may result in
                // monitor updates which aren't properly blocked or resumed, however that's fine - we don't
                // support async monitor updates even in LDK 0.0.116 and once we do we'll require no
                // downgrades to prior versions.
                (1, downstream_counterparty_and_funding_outpoint, option),
        },
);

#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) enum EventCompletionAction {
        ReleaseRAAChannelMonitorUpdate {
                counterparty_node_id: PublicKey,
                channel_funding_outpoint: OutPoint,
        },
}
impl_writeable_tlv_based_enum!(EventCompletionAction,
        (0, ReleaseRAAChannelMonitorUpdate) => {
                (0, channel_funding_outpoint, required),
                (2, counterparty_node_id, required),
        };
);

#[derive(Clone, PartialEq, Eq, Debug)]
/// If something is blocked on the completion of an RAA-generated [`ChannelMonitorUpdate`] we track
/// the blocked action here. See enum variants for more info.
pub(crate) enum RAAMonitorUpdateBlockingAction {
        /// A forwarded payment was claimed. We block the downstream channel completing its monitor
        /// update which removes the HTLC preimage until the upstream channel has gotten the preimage
        /// durably to disk.
        ForwardedPaymentInboundClaim {
                /// The upstream channel ID (i.e. the inbound edge).
                channel_id: ChannelId,
                /// The HTLC ID on the inbound edge.
                htlc_id: u64,
        },
}

impl RAAMonitorUpdateBlockingAction {
        fn from_prev_hop_data(prev_hop: &HTLCPreviousHopData) -> Self {
                Self::ForwardedPaymentInboundClaim {
                        channel_id: prev_hop.outpoint.to_channel_id(),
                        htlc_id: prev_hop.htlc_id,
                }
        }
}

impl_writeable_tlv_based_enum!(RAAMonitorUpdateBlockingAction,
        (0, ForwardedPaymentInboundClaim) => { (0, channel_id, required), (2, htlc_id, required) }
;);


/// State we hold per-peer.
pub(super) struct PeerState<SP: Deref> where SP::Target: SignerProvider {
        /// `channel_id` -> `ChannelPhase`
        ///
        /// Holds all channels within corresponding `ChannelPhase`s where the peer is the counterparty.
        pub(super) channel_by_id: HashMap<ChannelId, ChannelPhase<SP>>,
        /// `temporary_channel_id` -> `InboundChannelRequest`.
        ///
        /// When manual channel acceptance is enabled, this holds all unaccepted inbound channels where
        /// the peer is the counterparty. If the channel is accepted, then the entry in this table is
        /// removed, and an InboundV1Channel is created and placed in the `inbound_v1_channel_by_id` table. If
        /// the channel is rejected, then the entry is simply removed.
        pub(super) inbound_channel_request_by_id: HashMap<ChannelId, InboundChannelRequest>,
        /// The latest `InitFeatures` we heard from the peer.
        latest_features: InitFeatures,
        /// Messages to send to the peer - pushed to in the same lock that they are generated in (except
        /// for broadcast messages, where ordering isn't as strict).
        pub(super) pending_msg_events: Vec<MessageSendEvent>,
        /// Map from Channel IDs to pending [`ChannelMonitorUpdate`]s which have been passed to the
        /// user but which have not yet completed.
        ///
        /// Note that the channel may no longer exist. For example if the channel was closed but we
        /// later needed to claim an HTLC which is pending on-chain, we may generate a monitor update
        /// for a missing channel.
        in_flight_monitor_updates: BTreeMap<OutPoint, Vec<ChannelMonitorUpdate>>,
        /// Map from a specific channel to some action(s) that should be taken when all pending
        /// [`ChannelMonitorUpdate`]s for the channel complete updating.
        ///
        /// Note that because we generally only have one entry here a HashMap is pretty overkill. A
        /// BTreeMap currently stores more than ten elements per leaf node, so even up to a few
        /// channels with a peer this will just be one allocation and will amount to a linear list of
        /// channels to walk, avoiding the whole hashing rigmarole.
        ///
        /// Note that the channel may no longer exist. For example, if a channel was closed but we
        /// later needed to claim an HTLC which is pending on-chain, we may generate a monitor update
        /// for a missing channel. While a malicious peer could construct a second channel with the
        /// same `temporary_channel_id` (or final `channel_id` in the case of 0conf channels or prior
        /// to funding appearing on-chain), the downstream `ChannelMonitor` set is required to ensure
        /// duplicates do not occur, so such channels should fail without a monitor update completing.
        monitor_update_blocked_actions: BTreeMap<ChannelId, Vec<MonitorUpdateCompletionAction>>,
        /// If another channel's [`ChannelMonitorUpdate`] needs to complete before a channel we have
        /// with this peer can complete an RAA [`ChannelMonitorUpdate`] (e.g. because the RAA update
        /// will remove a preimage that needs to be durably in an upstream channel first), we put an
        /// entry here to note that the channel with the key's ID is blocked on a set of actions.
        actions_blocking_raa_monitor_updates: BTreeMap<ChannelId, Vec<RAAMonitorUpdateBlockingAction>>,
        /// The peer is currently connected (i.e. we've seen a
        /// [`ChannelMessageHandler::peer_connected`] and no corresponding
        /// [`ChannelMessageHandler::peer_disconnected`].
        is_connected: bool,
}

impl <SP: Deref> PeerState<SP> where SP::Target: SignerProvider {
        /// Indicates that a peer meets the criteria where we're ok to remove it from our storage.
        /// If true is passed for `require_disconnected`, the function will return false if we haven't
        /// disconnected from the node already, ie. `PeerState::is_connected` is set to `true`.
        fn ok_to_remove(&self, require_disconnected: bool) -> bool {
                if require_disconnected && self.is_connected {
                        return false
                }
                self.channel_by_id.iter().filter(|(_, phase)| matches!(phase, ChannelPhase::Funded(_))).count() == 0
                        && self.monitor_update_blocked_actions.is_empty()
                        && self.in_flight_monitor_updates.is_empty()
        }

        // Returns a count of all channels we have with this peer, including unfunded channels.
        fn total_channel_count(&self) -> usize {
                self.channel_by_id.len() + self.inbound_channel_request_by_id.len()
        }

        // Returns a bool indicating if the given `channel_id` matches a channel we have with this peer.
        fn has_channel(&self, channel_id: &ChannelId) -> bool {
                self.channel_by_id.contains_key(channel_id) ||
                        self.inbound_channel_request_by_id.contains_key(channel_id)
        }
}

/// A not-yet-accepted inbound (from counterparty) channel. Once
/// accepted, the parameters will be used to construct a channel.
pub(super) struct InboundChannelRequest {
        /// The original OpenChannel message.
        pub open_channel_msg: msgs::OpenChannel,
        /// The number of ticks remaining before the request expires.
        pub ticks_remaining: i32,
}

/// The number of ticks that may elapse while we're waiting for an unaccepted inbound channel to be
/// accepted. An unaccepted channel that exceeds this limit will be abandoned.
const UNACCEPTED_INBOUND_CHANNEL_AGE_LIMIT_TICKS: i32 = 2;

/// Stores a PaymentSecret and any other data we may need to validate an inbound payment is
/// actually ours and not some duplicate HTLC sent to us by a node along the route.
///
/// For users who don't want to bother doing their own payment preimage storage, we also store that
/// here.
///
/// Note that this struct will be removed entirely soon, in favor of storing no inbound payment data
/// and instead encoding it in the payment secret.
struct PendingInboundPayment {
        /// The payment secret that the sender must use for us to accept this payment
        payment_secret: PaymentSecret,
        /// Time at which this HTLC expires - blocks with a header time above this value will result in
        /// this payment being removed.
        expiry_time: u64,
        /// Arbitrary identifier the user specifies (or not)
        user_payment_id: u64,
        // Other required attributes of the payment, optionally enforced:
        payment_preimage: Option<PaymentPreimage>,
        min_value_msat: Option<u64>,
}

/// [`SimpleArcChannelManager`] is useful when you need a [`ChannelManager`] with a static lifetime, e.g.
/// when you're using `lightning-net-tokio` (since `tokio::spawn` requires parameters with static
/// lifetimes). Other times you can afford a reference, which is more efficient, in which case
/// [`SimpleRefChannelManager`] is the more appropriate type. Defining these type aliases prevents
/// issues such as overly long function definitions. Note that the `ChannelManager` can take any type
/// that implements [`NodeSigner`], [`EntropySource`], and [`SignerProvider`] for its keys manager,
/// or, respectively, [`Router`] for its router, but this type alias chooses the concrete types
/// of [`KeysManager`] and [`DefaultRouter`].
///
/// This is not exported to bindings users as type aliases aren't supported in most languages.
#[cfg(not(c_bindings))]
pub type SimpleArcChannelManager<M, T, F, L> = ChannelManager<
        Arc<M>,
        Arc<T>,
        Arc<KeysManager>,
        Arc<KeysManager>,
        Arc<KeysManager>,
        Arc<F>,
        Arc<DefaultRouter<
                Arc<NetworkGraph<Arc<L>>>,
                Arc<L>,
                Arc<RwLock<ProbabilisticScorer<Arc<NetworkGraph<Arc<L>>>, Arc<L>>>>,
                ProbabilisticScoringFeeParameters,
                ProbabilisticScorer<Arc<NetworkGraph<Arc<L>>>, Arc<L>>,
        >>,
        Arc<L>
>;

/// [`SimpleRefChannelManager`] is a type alias for a ChannelManager reference, and is the reference
/// counterpart to the [`SimpleArcChannelManager`] type alias. Use this type by default when you don't
/// need a ChannelManager with a static lifetime. You'll need a static lifetime in cases such as
/// usage of lightning-net-tokio (since `tokio::spawn` requires parameters with static lifetimes).
/// But if this is not necessary, using a reference is more efficient. Defining these type aliases
/// issues such as overly long function definitions. Note that the ChannelManager can take any type
/// that implements [`NodeSigner`], [`EntropySource`], and [`SignerProvider`] for its keys manager,
/// or, respectively, [`Router`]  for its router, but this type alias chooses the concrete types
/// of [`KeysManager`] and [`DefaultRouter`].
///
/// This is not exported to bindings users as type aliases aren't supported in most languages.
#[cfg(not(c_bindings))]
pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L> =
        ChannelManager<
                &'a M,
                &'b T,
                &'c KeysManager,
                &'c KeysManager,
                &'c KeysManager,
                &'d F,
                &'e DefaultRouter<
                        &'f NetworkGraph<&'g L>,
                        &'g L,
                        &'h RwLock<ProbabilisticScorer<&'f NetworkGraph<&'g L>, &'g L>>,
                        ProbabilisticScoringFeeParameters,
                        ProbabilisticScorer<&'f NetworkGraph<&'g L>, &'g L>
                >,
                &'g L
        >;

/// A trivial trait which describes any [`ChannelManager`].
///
/// This is not exported to bindings users as general cover traits aren't useful in other
/// languages.
pub trait AChannelManager {
        /// A type implementing [`chain::Watch`].
        type Watch: chain::Watch<Self::Signer> + ?Sized;
        /// A type that may be dereferenced to [`Self::Watch`].
        type M: Deref<Target = Self::Watch>;
        /// A type implementing [`BroadcasterInterface`].
        type Broadcaster: BroadcasterInterface + ?Sized;
        /// A type that may be dereferenced to [`Self::Broadcaster`].
        type T: Deref<Target = Self::Broadcaster>;
        /// A type implementing [`EntropySource`].
        type EntropySource: EntropySource + ?Sized;
        /// A type that may be dereferenced to [`Self::EntropySource`].
        type ES: Deref<Target = Self::EntropySource>;
        /// A type implementing [`NodeSigner`].
        type NodeSigner: NodeSigner + ?Sized;
        /// A type that may be dereferenced to [`Self::NodeSigner`].
        type NS: Deref<Target = Self::NodeSigner>;
        /// A type implementing [`WriteableEcdsaChannelSigner`].
        type Signer: WriteableEcdsaChannelSigner + Sized;
        /// A type implementing [`SignerProvider`] for [`Self::Signer`].
        type SignerProvider: SignerProvider<EcdsaSigner= Self::Signer> + ?Sized;
        /// A type that may be dereferenced to [`Self::SignerProvider`].
        type SP: Deref<Target = Self::SignerProvider>;
        /// A type implementing [`FeeEstimator`].
        type FeeEstimator: FeeEstimator + ?Sized;
        /// A type that may be dereferenced to [`Self::FeeEstimator`].
        type F: Deref<Target = Self::FeeEstimator>;
        /// A type implementing [`Router`].
        type Router: Router + ?Sized;
        /// A type that may be dereferenced to [`Self::Router`].
        type R: Deref<Target = Self::Router>;
        /// A type implementing [`Logger`].
        type Logger: Logger + ?Sized;
        /// A type that may be dereferenced to [`Self::Logger`].
        type L: Deref<Target = Self::Logger>;
        /// Returns a reference to the actual [`ChannelManager`] object.
        fn get_cm(&self) -> &ChannelManager<Self::M, Self::T, Self::ES, Self::NS, Self::SP, Self::F, Self::R, Self::L>;
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> AChannelManager
for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        type Watch = M::Target;
        type M = M;
        type Broadcaster = T::Target;
        type T = T;
        type EntropySource = ES::Target;
        type ES = ES;
        type NodeSigner = NS::Target;
        type NS = NS;
        type Signer = <SP::Target as SignerProvider>::EcdsaSigner;
        type SignerProvider = SP::Target;
        type SP = SP;
        type FeeEstimator = F::Target;
        type F = F;
        type Router = R::Target;
        type R = R;
        type Logger = L::Target;
        type L = L;
        fn get_cm(&self) -> &ChannelManager<M, T, ES, NS, SP, F, R, L> { self }
}

/// Manager which keeps track of a number of channels and sends messages to the appropriate
/// channel, also tracking HTLC preimages and forwarding onion packets appropriately.
///
/// Implements [`ChannelMessageHandler`], handling the multi-channel parts and passing things through
/// to individual Channels.
///
/// Implements [`Writeable`] to write out all channel state to disk. Implies [`peer_disconnected`] for
/// all peers during write/read (though does not modify this instance, only the instance being
/// serialized). This will result in any channels which have not yet exchanged [`funding_created`] (i.e.,
/// called [`funding_transaction_generated`] for outbound channels) being closed.
///
/// Note that you can be a bit lazier about writing out `ChannelManager` than you can be with
/// [`ChannelMonitor`]. With [`ChannelMonitor`] you MUST durably write each
/// [`ChannelMonitorUpdate`] before returning from
/// [`chain::Watch::watch_channel`]/[`update_channel`] or before completing async writes. With
/// `ChannelManager`s, writing updates happens out-of-band (and will prevent any other
/// `ChannelManager` operations from occurring during the serialization process). If the
/// deserialized version is out-of-date compared to the [`ChannelMonitor`] passed by reference to
/// [`read`], those channels will be force-closed based on the `ChannelMonitor` state and no funds
/// will be lost (modulo on-chain transaction fees).
///
/// Note that the deserializer is only implemented for `(`[`BlockHash`]`, `[`ChannelManager`]`)`, which
/// tells you the last block hash which was connected. You should get the best block tip before using the manager.
/// See [`chain::Listen`] and [`chain::Confirm`] for more details.
///
/// Note that `ChannelManager` is responsible for tracking liveness of its channels and generating
/// [`ChannelUpdate`] messages informing peers that the channel is temporarily disabled. To avoid
/// spam due to quick disconnection/reconnection, updates are not sent until the channel has been
/// offline for a full minute. In order to track this, you must call
/// [`timer_tick_occurred`] roughly once per minute, though it doesn't have to be perfect.
///
/// To avoid trivial DoS issues, `ChannelManager` limits the number of inbound connections and
/// inbound channels without confirmed funding transactions. This may result in nodes which we do
/// not have a channel with being unable to connect to us or open new channels with us if we have
/// many peers with unfunded channels.
///
/// Because it is an indication of trust, inbound channels which we've accepted as 0conf are
/// exempted from the count of unfunded channels. Similarly, outbound channels and connections are
/// never limited. Please ensure you limit the count of such channels yourself.
///
/// Rather than using a plain `ChannelManager`, it is preferable to use either a [`SimpleArcChannelManager`]
/// a [`SimpleRefChannelManager`], for conciseness. See their documentation for more details, but
/// essentially you should default to using a [`SimpleRefChannelManager`], and use a
/// [`SimpleArcChannelManager`] when you require a `ChannelManager` with a static lifetime, such as when
/// you're using lightning-net-tokio.
///
/// [`peer_disconnected`]: msgs::ChannelMessageHandler::peer_disconnected
/// [`funding_created`]: msgs::FundingCreated
/// [`funding_transaction_generated`]: Self::funding_transaction_generated
/// [`BlockHash`]: bitcoin::hash_types::BlockHash
/// [`update_channel`]: chain::Watch::update_channel
/// [`ChannelUpdate`]: msgs::ChannelUpdate
/// [`timer_tick_occurred`]: Self::timer_tick_occurred
/// [`read`]: ReadableArgs::read
//
// Lock order:
// The tree structure below illustrates the lock order requirements for the different locks of the
// `ChannelManager`. Locks can be held at the same time if they are on the same branch in the tree,
// and should then be taken in the order of the lowest to the highest level in the tree.
// Note that locks on different branches shall not be taken at the same time, as doing so will
// create a new lock order for those specific locks in the order they were taken.
//
// Lock order tree:
//
// `pending_offers_messages`
//
// `total_consistency_lock`
//  |
//  |__`forward_htlcs`
//  |   |
//  |   |__`pending_intercepted_htlcs`
//  |
//  |__`per_peer_state`
//      |
//      |__`pending_inbound_payments`
//          |
//          |__`claimable_payments`
//          |
//          |__`pending_outbound_payments` // This field's struct contains a map of pending outbounds
//              |
//              |__`peer_state`
//                  |
//                  |__`id_to_peer`
//                  |
//                  |__`short_to_chan_info`
//                  |
//                  |__`outbound_scid_aliases`
//                  |
//                  |__`best_block`
//                  |
//                  |__`pending_events`
//                      |
//                      |__`pending_background_events`
//
pub struct ChannelManager<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        default_configuration: UserConfig,
        chain_hash: ChainHash,
        fee_estimator: LowerBoundedFeeEstimator<F>,
        chain_monitor: M,
        tx_broadcaster: T,
        #[allow(unused)]
        router: R,

        /// See `ChannelManager` struct-level documentation for lock order requirements.
        #[cfg(test)]
        pub(super) best_block: RwLock<BestBlock>,
        #[cfg(not(test))]
        best_block: RwLock<BestBlock>,
        secp_ctx: Secp256k1<secp256k1::All>,

        /// Storage for PaymentSecrets and any requirements on future inbound payments before we will
        /// expose them to users via a PaymentClaimable event. HTLCs which do not meet the requirements
        /// here are failed when we process them as pending-forwardable-HTLCs, and entries are removed
        /// after we generate a PaymentClaimable upon receipt of all MPP parts or when they time out.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        pending_inbound_payments: Mutex<HashMap<PaymentHash, PendingInboundPayment>>,

        /// The session_priv bytes and retry metadata of outbound payments which are pending resolution.
        /// The authoritative state of these HTLCs resides either within Channels or ChannelMonitors
        /// (if the channel has been force-closed), however we track them here to prevent duplicative
        /// PaymentSent/PaymentPathFailed events. Specifically, in the case of a duplicative
        /// update_fulfill_htlc message after a reconnect, we may "claim" a payment twice.
        /// Additionally, because ChannelMonitors are often not re-serialized after connecting block(s)
        /// which may generate a claim event, we may receive similar duplicate claim/fail MonitorEvents
        /// after reloading from disk while replaying blocks against ChannelMonitors.
        ///
        /// See `PendingOutboundPayment` documentation for more info.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        pending_outbound_payments: OutboundPayments,

        /// SCID/SCID Alias -> forward infos. Key of 0 means payments received.
        ///
        /// Note that because we may have an SCID Alias as the key we can have two entries per channel,
        /// though in practice we probably won't be receiving HTLCs for a channel both via the alias
        /// and via the classic SCID.
        ///
        /// Note that no consistency guarantees are made about the existence of a channel with the
        /// `short_channel_id` here, nor the `short_channel_id` in the `PendingHTLCInfo`!
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        #[cfg(test)]
        pub(super) forward_htlcs: Mutex<HashMap<u64, Vec<HTLCForwardInfo>>>,
        #[cfg(not(test))]
        forward_htlcs: Mutex<HashMap<u64, Vec<HTLCForwardInfo>>>,
        /// Storage for HTLCs that have been intercepted and bubbled up to the user. We hold them here
        /// until the user tells us what we should do with them.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        pending_intercepted_htlcs: Mutex<HashMap<InterceptId, PendingAddHTLCInfo>>,

        /// The sets of payments which are claimable or currently being claimed. See
        /// [`ClaimablePayments`]' individual field docs for more info.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        claimable_payments: Mutex<ClaimablePayments>,

        /// The set of outbound SCID aliases across all our channels, including unconfirmed channels
        /// and some closed channels which reached a usable state prior to being closed. This is used
        /// only to avoid duplicates, and is not persisted explicitly to disk, but rebuilt from the
        /// active channel list on load.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        outbound_scid_aliases: Mutex<HashSet<u64>>,

        /// `channel_id` -> `counterparty_node_id`.
        ///
        /// Only `channel_id`s are allowed as keys in this map, and not `temporary_channel_id`s. As
        /// multiple channels with the same `temporary_channel_id` to different peers can exist,
        /// allowing `temporary_channel_id`s in this map would cause collisions for such channels.
        ///
        /// Note that this map should only be used for `MonitorEvent` handling, to be able to access
        /// the corresponding channel for the event, as we only have access to the `channel_id` during
        /// the handling of the events.
        ///
        /// Note that no consistency guarantees are made about the existence of a peer with the
        /// `counterparty_node_id` in our other maps.
        ///
        /// TODO:
        /// The `counterparty_node_id` isn't passed with `MonitorEvent`s currently. To pass it, we need
        /// to make `counterparty_node_id`'s a required field in `ChannelMonitor`s, which unfortunately
        /// would break backwards compatability.
        /// We should add `counterparty_node_id`s to `MonitorEvent`s, and eventually rely on it in the
        /// future. That would make this map redundant, as only the `ChannelManager::per_peer_state` is
        /// required to access the channel with the `counterparty_node_id`.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        id_to_peer: Mutex<HashMap<ChannelId, PublicKey>>,

        /// SCIDs (and outbound SCID aliases) -> `counterparty_node_id`s and `channel_id`s.
        ///
        /// Outbound SCID aliases are added here once the channel is available for normal use, with
        /// SCIDs being added once the funding transaction is confirmed at the channel's required
        /// confirmation depth.
        ///
        /// Note that while this holds `counterparty_node_id`s and `channel_id`s, no consistency
        /// guarantees are made about the existence of a peer with the `counterparty_node_id` nor a
        /// channel with the `channel_id` in our other maps.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        #[cfg(test)]
        pub(super) short_to_chan_info: FairRwLock<HashMap<u64, (PublicKey, ChannelId)>>,
        #[cfg(not(test))]
        short_to_chan_info: FairRwLock<HashMap<u64, (PublicKey, ChannelId)>>,

        our_network_pubkey: PublicKey,

        inbound_payment_key: inbound_payment::ExpandedKey,

        /// LDK puts the [fake scids] that it generates into namespaces, to identify the type of an
        /// incoming payment. To make it harder for a third-party to identify the type of a payment,
        /// we encrypt the namespace identifier using these bytes.
        ///
        /// [fake scids]: crate::util::scid_utils::fake_scid
        fake_scid_rand_bytes: [u8; 32],

        /// When we send payment probes, we generate the [`PaymentHash`] based on this cookie secret
        /// and a random [`PaymentId`]. This allows us to discern probes from real payments, without
        /// keeping additional state.
        probing_cookie_secret: [u8; 32],

        /// The highest block timestamp we've seen, which is usually a good guess at the current time.
        /// Assuming most miners are generating blocks with reasonable timestamps, this shouldn't be
        /// very far in the past, and can only ever be up to two hours in the future.
        highest_seen_timestamp: AtomicUsize,

        /// The bulk of our storage. Currently the `per_peer_state` stores our channels on a per-peer
        /// basis, as well as the peer's latest features.
        ///
        /// If we are connected to a peer we always at least have an entry here, even if no channels
        /// are currently open with that peer.
        ///
        /// Because adding or removing an entry is rare, we usually take an outer read lock and then
        /// operate on the inner value freely. This opens up for parallel per-peer operation for
        /// channels.
        ///
        /// Note that the same thread must never acquire two inner `PeerState` locks at the same time.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        #[cfg(not(any(test, feature = "_test_utils")))]
        per_peer_state: FairRwLock<HashMap<PublicKey, Mutex<PeerState<SP>>>>,
        #[cfg(any(test, feature = "_test_utils"))]
        pub(super) per_peer_state: FairRwLock<HashMap<PublicKey, Mutex<PeerState<SP>>>>,

        /// The set of events which we need to give to the user to handle. In some cases an event may
        /// require some further action after the user handles it (currently only blocking a monitor
        /// update from being handed to the user to ensure the included changes to the channel state
        /// are handled by the user before they're persisted durably to disk). In that case, the second
        /// element in the tuple is set to `Some` with further details of the action.
        ///
        /// Note that events MUST NOT be removed from pending_events after deserialization, as they
        /// could be in the middle of being processed without the direct mutex held.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        #[cfg(not(any(test, feature = "_test_utils")))]
        pending_events: Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>,
        #[cfg(any(test, feature = "_test_utils"))]
        pub(crate) pending_events: Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>,

        /// A simple atomic flag to ensure only one task at a time can be processing events asynchronously.
        pending_events_processor: AtomicBool,

        /// If we are running during init (either directly during the deserialization method or in
        /// block connection methods which run after deserialization but before normal operation) we
        /// cannot provide the user with [`ChannelMonitorUpdate`]s through the normal update flow -
        /// prior to normal operation the user may not have loaded the [`ChannelMonitor`]s into their
        /// [`ChainMonitor`] and thus attempting to update it will fail or panic.
        ///
        /// Thus, we place them here to be handled as soon as possible once we are running normally.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        ///
        /// [`ChainMonitor`]: crate::chain::chainmonitor::ChainMonitor
        pending_background_events: Mutex<Vec<BackgroundEvent>>,
        /// Used when we have to take a BIG lock to make sure everything is self-consistent.
        /// Essentially just when we're serializing ourselves out.
        /// Taken first everywhere where we are making changes before any other locks.
        /// When acquiring this lock in read mode, rather than acquiring it directly, call
        /// `PersistenceNotifierGuard::notify_on_drop(..)` and pass the lock to it, to ensure the
        /// Notifier the lock contains sends out a notification when the lock is released.
        total_consistency_lock: RwLock<()>,
        /// Tracks the progress of channels going through batch funding by whether funding_signed was
        /// received and the monitor has been persisted.
        ///
        /// This information does not need to be persisted as funding nodes can forget
        /// unfunded channels upon disconnection.
        funding_batch_states: Mutex<BTreeMap<Txid, Vec<(ChannelId, PublicKey, bool)>>>,

        background_events_processed_since_startup: AtomicBool,

        event_persist_notifier: Notifier,
        needs_persist_flag: AtomicBool,

        pending_offers_messages: Mutex<Vec<PendingOnionMessage<OffersMessage>>>,

        entropy_source: ES,
        node_signer: NS,
        signer_provider: SP,

        logger: L,
}

/// Chain-related parameters used to construct a new `ChannelManager`.
///
/// Typically, the block-specific parameters are derived from the best block hash for the network,
/// as a newly constructed `ChannelManager` will not have created any channels yet. These parameters
/// are not needed when deserializing a previously constructed `ChannelManager`.
#[derive(Clone, Copy, PartialEq)]
pub struct ChainParameters {
        /// The network for determining the `chain_hash` in Lightning messages.
        pub network: Network,

        /// The hash and height of the latest block successfully connected.
        ///
        /// Used to track on-chain channel funding outputs and send payments with reliable timelocks.
        pub best_block: BestBlock,
}

#[derive(Copy, Clone, PartialEq)]
#[must_use]
enum NotifyOption {
        DoPersist,
        SkipPersistHandleEvents,
        SkipPersistNoEvents,
}

/// Whenever we release the `ChannelManager`'s `total_consistency_lock`, from read mode, it is
/// desirable to notify any listeners on `await_persistable_update_timeout`/
/// `await_persistable_update` when new updates are available for persistence. Therefore, this
/// struct is responsible for locking the total consistency lock and, upon going out of scope,
/// sending the aforementioned notification (since the lock being released indicates that the
/// updates are ready for persistence).
///
/// We allow callers to either always notify by constructing with `notify_on_drop` or choose to
/// notify or not based on whether relevant changes have been made, providing a closure to
/// `optionally_notify` which returns a `NotifyOption`.
struct PersistenceNotifierGuard<'a, F: FnMut() -> NotifyOption> {
        event_persist_notifier: &'a Notifier,
        needs_persist_flag: &'a AtomicBool,
        should_persist: F,
        // We hold onto this result so the lock doesn't get released immediately.
        _read_guard: RwLockReadGuard<'a, ()>,
}

impl<'a> PersistenceNotifierGuard<'a, fn() -> NotifyOption> { // We don't care what the concrete F is here, it's unused
        /// Notifies any waiters and indicates that we need to persist, in addition to possibly having
        /// events to handle.
        ///
        /// This must always be called if the changes included a `ChannelMonitorUpdate`, as well as in
        /// other cases where losing the changes on restart may result in a force-close or otherwise
        /// isn't ideal.
        fn notify_on_drop<C: AChannelManager>(cm: &'a C) -> PersistenceNotifierGuard<'a, impl FnMut() -> NotifyOption> {
                Self::optionally_notify(cm, || -> NotifyOption { NotifyOption::DoPersist })
        }

        fn optionally_notify<F: FnMut() -> NotifyOption, C: AChannelManager>(cm: &'a C, mut persist_check: F)
        -> PersistenceNotifierGuard<'a, impl FnMut() -> NotifyOption> {
                let read_guard = cm.get_cm().total_consistency_lock.read().unwrap();
                let force_notify = cm.get_cm().process_background_events();

                PersistenceNotifierGuard {
                        event_persist_notifier: &cm.get_cm().event_persist_notifier,
                        needs_persist_flag: &cm.get_cm().needs_persist_flag,
                        should_persist: move || {
                                // Pick the "most" action between `persist_check` and the background events
                                // processing and return that.
                                let notify = persist_check();
                                match (notify, force_notify) {
                                        (NotifyOption::DoPersist, _) => NotifyOption::DoPersist,
                                        (_, NotifyOption::DoPersist) => NotifyOption::DoPersist,
                                        (NotifyOption::SkipPersistHandleEvents, _) => NotifyOption::SkipPersistHandleEvents,
                                        (_, NotifyOption::SkipPersistHandleEvents) => NotifyOption::SkipPersistHandleEvents,
                                        _ => NotifyOption::SkipPersistNoEvents,
                                }
                        },
                        _read_guard: read_guard,
                }
        }

        /// Note that if any [`ChannelMonitorUpdate`]s are possibly generated,
        /// [`ChannelManager::process_background_events`] MUST be called first (or
        /// [`Self::optionally_notify`] used).
        fn optionally_notify_skipping_background_events<F: Fn() -> NotifyOption, C: AChannelManager>
        (cm: &'a C, persist_check: F) -> PersistenceNotifierGuard<'a, F> {
                let read_guard = cm.get_cm().total_consistency_lock.read().unwrap();

                PersistenceNotifierGuard {
                        event_persist_notifier: &cm.get_cm().event_persist_notifier,
                        needs_persist_flag: &cm.get_cm().needs_persist_flag,
                        should_persist: persist_check,
                        _read_guard: read_guard,
                }
        }
}

impl<'a, F: FnMut() -> NotifyOption> Drop for PersistenceNotifierGuard<'a, F> {
        fn drop(&mut self) {
                match (self.should_persist)() {
                        NotifyOption::DoPersist => {
                                self.needs_persist_flag.store(true, Ordering::Release);
                                self.event_persist_notifier.notify()
                        },
                        NotifyOption::SkipPersistHandleEvents =>
                                self.event_persist_notifier.notify(),
                        NotifyOption::SkipPersistNoEvents => {},
                }
        }
}

/// The amount of time in blocks we require our counterparty wait to claim their money (ie time
/// between when we, or our watchtower, must check for them having broadcast a theft transaction).
///
/// This can be increased (but not decreased) through [`ChannelHandshakeConfig::our_to_self_delay`]
///
/// [`ChannelHandshakeConfig::our_to_self_delay`]: crate::util::config::ChannelHandshakeConfig::our_to_self_delay
pub const BREAKDOWN_TIMEOUT: u16 = 6 * 24;
/// The amount of time in blocks we're willing to wait to claim money back to us. This matches
/// the maximum required amount in lnd as of March 2021.
pub(crate) const MAX_LOCAL_BREAKDOWN_TIMEOUT: u16 = 2 * 6 * 24 * 7;

/// The minimum number of blocks between an inbound HTLC's CLTV and the corresponding outbound
/// HTLC's CLTV. The current default represents roughly seven hours of blocks at six blocks/hour.
///
/// This can be increased (but not decreased) through [`ChannelConfig::cltv_expiry_delta`]
///
/// [`ChannelConfig::cltv_expiry_delta`]: crate::util::config::ChannelConfig::cltv_expiry_delta
// This should always be a few blocks greater than channelmonitor::CLTV_CLAIM_BUFFER,
// i.e. the node we forwarded the payment on to should always have enough room to reliably time out
// the HTLC via a full update_fail_htlc/commitment_signed dance before we hit the
// CLTV_CLAIM_BUFFER point (we static assert that it's at least 3 blocks more).
pub const MIN_CLTV_EXPIRY_DELTA: u16 = 6*7;
// This should be long enough to allow a payment path drawn across multiple routing hops with substantial
// `cltv_expiry_delta`. Indeed, the length of those values is the reaction delay offered to a routing node
// in case of HTLC on-chain settlement. While appearing less competitive, a node operator could decide to
// scale them up to suit its security policy. At the network-level, we shouldn't constrain them too much,
// while avoiding to introduce a DoS vector. Further, a low CTLV_FAR_FAR_AWAY could be a source of
// routing failure for any HTLC sender picking up an LDK node among the first hops.
pub(super) const CLTV_FAR_FAR_AWAY: u32 = 14 * 24 * 6;

/// Minimum CLTV difference between the current block height and received inbound payments.
/// Invoices generated for payment to us must set their `min_final_cltv_expiry_delta` field to at least
/// this value.
// Note that we fail if exactly HTLC_FAIL_BACK_BUFFER + 1 was used, so we need to add one for
// any payments to succeed. Further, we don't want payments to fail if a block was found while
// a payment was being routed, so we add an extra block to be safe.
pub const MIN_FINAL_CLTV_EXPIRY_DELTA: u16 = HTLC_FAIL_BACK_BUFFER as u16 + 3;

// Check that our CLTV_EXPIRY is at least CLTV_CLAIM_BUFFER + ANTI_REORG_DELAY + LATENCY_GRACE_PERIOD_BLOCKS,
// ie that if the next-hop peer fails the HTLC within
// LATENCY_GRACE_PERIOD_BLOCKS then we'll still have CLTV_CLAIM_BUFFER left to timeout it onchain,
// then waiting ANTI_REORG_DELAY to be reorg-safe on the outbound HLTC and
// failing the corresponding htlc backward, and us now seeing the last block of ANTI_REORG_DELAY before
// LATENCY_GRACE_PERIOD_BLOCKS.
#[deny(const_err)]
#[allow(dead_code)]
const CHECK_CLTV_EXPIRY_SANITY: u32 = MIN_CLTV_EXPIRY_DELTA as u32 - LATENCY_GRACE_PERIOD_BLOCKS - CLTV_CLAIM_BUFFER - ANTI_REORG_DELAY - LATENCY_GRACE_PERIOD_BLOCKS;

// Check for ability of an attacker to make us fail on-chain by delaying an HTLC claim. See
// ChannelMonitor::should_broadcast_holder_commitment_txn for a description of why this is needed.
#[deny(const_err)]
#[allow(dead_code)]
const CHECK_CLTV_EXPIRY_SANITY_2: u32 = MIN_CLTV_EXPIRY_DELTA as u32 - LATENCY_GRACE_PERIOD_BLOCKS - 2*CLTV_CLAIM_BUFFER;

/// The number of ticks of [`ChannelManager::timer_tick_occurred`] until expiry of incomplete MPPs
pub(crate) const MPP_TIMEOUT_TICKS: u8 = 3;

/// The number of ticks of [`ChannelManager::timer_tick_occurred`] where a peer is disconnected
/// until we mark the channel disabled and gossip the update.
pub(crate) const DISABLE_GOSSIP_TICKS: u8 = 10;

/// The number of ticks of [`ChannelManager::timer_tick_occurred`] where a peer is connected until
/// we mark the channel enabled and gossip the update.
pub(crate) const ENABLE_GOSSIP_TICKS: u8 = 5;

/// The maximum number of unfunded channels we can have per-peer before we start rejecting new
/// (inbound) ones. The number of peers with unfunded channels is limited separately in
/// [`MAX_UNFUNDED_CHANNEL_PEERS`].
const MAX_UNFUNDED_CHANS_PER_PEER: usize = 4;

/// The maximum number of peers from which we will allow pending unfunded channels. Once we reach
/// this many peers we reject new (inbound) channels from peers with which we don't have a channel.
const MAX_UNFUNDED_CHANNEL_PEERS: usize = 50;

/// The maximum number of peers which we do not have a (funded) channel with. Once we reach this
/// many peers we reject new (inbound) connections.
const MAX_NO_CHANNEL_PEERS: usize = 250;

/// Information needed for constructing an invoice route hint for this channel.
#[derive(Clone, Debug, PartialEq)]
pub struct CounterpartyForwardingInfo {
        /// Base routing fee in millisatoshis.
        pub fee_base_msat: u32,
        /// Amount in millionths of a satoshi the channel will charge per transferred satoshi.
        pub fee_proportional_millionths: u32,
        /// The minimum difference in cltv_expiry between an ingoing HTLC and its outgoing counterpart,
        /// such that the outgoing HTLC is forwardable to this counterparty. See `msgs::ChannelUpdate`'s
        /// `cltv_expiry_delta` for more details.
        pub cltv_expiry_delta: u16,
}

/// Channel parameters which apply to our counterparty. These are split out from [`ChannelDetails`]
/// to better separate parameters.
#[derive(Clone, Debug, PartialEq)]
pub struct ChannelCounterparty {
        /// The node_id of our counterparty
        pub node_id: PublicKey,
        /// The Features the channel counterparty provided upon last connection.
        /// Useful for routing as it is the most up-to-date copy of the counterparty's features and
        /// many routing-relevant features are present in the init context.
        pub features: InitFeatures,
        /// The value, in satoshis, that must always be held in the channel for our counterparty. This
        /// value ensures that if our counterparty broadcasts a revoked state, we can punish them by
        /// claiming at least this value on chain.
        ///
        /// This value is not included in [`inbound_capacity_msat`] as it can never be spent.
        ///
        /// [`inbound_capacity_msat`]: ChannelDetails::inbound_capacity_msat
        pub unspendable_punishment_reserve: u64,
        /// Information on the fees and requirements that the counterparty requires when forwarding
        /// payments to us through this channel.
        pub forwarding_info: Option<CounterpartyForwardingInfo>,
        /// The smallest value HTLC (in msat) the remote peer will accept, for this channel. This field
        /// is only `None` before we have received either the `OpenChannel` or `AcceptChannel` message
        /// from the remote peer, or for `ChannelCounterparty` objects serialized prior to LDK 0.0.107.
        pub outbound_htlc_minimum_msat: Option<u64>,
        /// The largest value HTLC (in msat) the remote peer currently will accept, for this channel.
        pub outbound_htlc_maximum_msat: Option<u64>,
}

/// Details of a channel, as returned by [`ChannelManager::list_channels`] and [`ChannelManager::list_usable_channels`]
#[derive(Clone, Debug, PartialEq)]
pub struct ChannelDetails {
        /// The channel's ID (prior to funding transaction generation, this is a random 32 bytes,
        /// thereafter this is the txid of the funding transaction xor the funding transaction output).
        /// Note that this means this value is *not* persistent - it can change once during the
        /// lifetime of the channel.
        pub channel_id: ChannelId,
        /// Parameters which apply to our counterparty. See individual fields for more information.
        pub counterparty: ChannelCounterparty,
        /// The Channel's funding transaction output, if we've negotiated the funding transaction with
        /// our counterparty already.
        ///
        /// Note that, if this has been set, `channel_id` will be equivalent to
        /// `funding_txo.unwrap().to_channel_id()`.
        pub funding_txo: Option<OutPoint>,
        /// The features which this channel operates with. See individual features for more info.
        ///
        /// `None` until negotiation completes and the channel type is finalized.
        pub channel_type: Option<ChannelTypeFeatures>,
        /// The position of the funding transaction in the chain. None if the funding transaction has
        /// not yet been confirmed and the channel fully opened.
        ///
        /// Note that if [`inbound_scid_alias`] is set, it must be used for invoices and inbound
        /// payments instead of this. See [`get_inbound_payment_scid`].
        ///
        /// For channels with [`confirmations_required`] set to `Some(0)`, [`outbound_scid_alias`] may
        /// be used in place of this in outbound routes. See [`get_outbound_payment_scid`].
        ///
        /// [`inbound_scid_alias`]: Self::inbound_scid_alias
        /// [`outbound_scid_alias`]: Self::outbound_scid_alias
        /// [`get_inbound_payment_scid`]: Self::get_inbound_payment_scid
        /// [`get_outbound_payment_scid`]: Self::get_outbound_payment_scid
        /// [`confirmations_required`]: Self::confirmations_required
        pub short_channel_id: Option<u64>,
        /// An optional [`short_channel_id`] alias for this channel, randomly generated by us and
        /// usable in place of [`short_channel_id`] to reference the channel in outbound routes when
        /// the channel has not yet been confirmed (as long as [`confirmations_required`] is
        /// `Some(0)`).
        ///
        /// This will be `None` as long as the channel is not available for routing outbound payments.
        ///
        /// [`short_channel_id`]: Self::short_channel_id
        /// [`confirmations_required`]: Self::confirmations_required
        pub outbound_scid_alias: Option<u64>,
        /// An optional [`short_channel_id`] alias for this channel, randomly generated by our
        /// counterparty and usable in place of [`short_channel_id`] in invoice route hints. Our
        /// counterparty will recognize the alias provided here in place of the [`short_channel_id`]
        /// when they see a payment to be routed to us.
        ///
        /// Our counterparty may choose to rotate this value at any time, though will always recognize
        /// previous values for inbound payment forwarding.
        ///
        /// [`short_channel_id`]: Self::short_channel_id
        pub inbound_scid_alias: Option<u64>,
        /// The value, in satoshis, of this channel as appears in the funding output
        pub channel_value_satoshis: u64,
        /// The value, in satoshis, that must always be held in the channel for us. This value ensures
        /// that if we broadcast a revoked state, our counterparty can punish us by claiming at least
        /// this value on chain.
        ///
        /// This value is not included in [`outbound_capacity_msat`] as it can never be spent.
        ///
        /// This value will be `None` for outbound channels until the counterparty accepts the channel.
        ///
        /// [`outbound_capacity_msat`]: ChannelDetails::outbound_capacity_msat
        pub unspendable_punishment_reserve: Option<u64>,
        /// The `user_channel_id` value passed in to [`ChannelManager::create_channel`] for outbound
        /// channels, or to [`ChannelManager::accept_inbound_channel`] for inbound channels if
        /// [`UserConfig::manually_accept_inbound_channels`] config flag is set to true. Otherwise
        /// `user_channel_id` will be randomized for an inbound channel.  This may be zero for objects
        /// serialized with LDK versions prior to 0.0.113.
        ///
        /// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
        /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
        /// [`UserConfig::manually_accept_inbound_channels`]: crate::util::config::UserConfig::manually_accept_inbound_channels
        pub user_channel_id: u128,
        /// The currently negotiated fee rate denominated in satoshi per 1000 weight units,
        /// which is applied to commitment and HTLC transactions.
        ///
        /// This value will be `None` for objects serialized with LDK versions prior to 0.0.115.
        pub feerate_sat_per_1000_weight: Option<u32>,
        /// Our total balance.  This is the amount we would get if we close the channel.
        /// This value is not exact. Due to various in-flight changes and feerate changes, exactly this
        /// amount is not likely to be recoverable on close.
        ///
        /// This does not include any pending HTLCs which are not yet fully resolved (and, thus, whose
        /// balance is not available for inclusion in new outbound HTLCs). This further does not include
        /// any pending outgoing HTLCs which are awaiting some other resolution to be sent.
        /// This does not consider any on-chain fees.
        ///
        /// See also [`ChannelDetails::outbound_capacity_msat`]
        pub balance_msat: u64,
        /// The available outbound capacity for sending HTLCs to the remote peer. This does not include
        /// any pending HTLCs which are not yet fully resolved (and, thus, whose balance is not
        /// available for inclusion in new outbound HTLCs). This further does not include any pending
        /// outgoing HTLCs which are awaiting some other resolution to be sent.
        ///
        /// See also [`ChannelDetails::balance_msat`]
        ///
        /// This value is not exact. Due to various in-flight changes, feerate changes, and our
        /// conflict-avoidance policy, exactly this amount is not likely to be spendable. However, we
        /// should be able to spend nearly this amount.
        pub outbound_capacity_msat: u64,
        /// The available outbound capacity for sending a single HTLC to the remote peer. This is
        /// similar to [`ChannelDetails::outbound_capacity_msat`] but it may be further restricted by
        /// the current state and per-HTLC limit(s). This is intended for use when routing, allowing us
        /// to use a limit as close as possible to the HTLC limit we can currently send.
        ///
        /// See also [`ChannelDetails::next_outbound_htlc_minimum_msat`],
        /// [`ChannelDetails::balance_msat`], and [`ChannelDetails::outbound_capacity_msat`].
        pub next_outbound_htlc_limit_msat: u64,
        /// The minimum value for sending a single HTLC to the remote peer. This is the equivalent of
        /// [`ChannelDetails::next_outbound_htlc_limit_msat`] but represents a lower-bound, rather than
        /// an upper-bound. This is intended for use when routing, allowing us to ensure we pick a
        /// route which is valid.
        pub next_outbound_htlc_minimum_msat: u64,
        /// The available inbound capacity for the remote peer to send HTLCs to us. This does not
        /// include any pending HTLCs which are not yet fully resolved (and, thus, whose balance is not
        /// available for inclusion in new inbound HTLCs).
        /// Note that there are some corner cases not fully handled here, so the actual available
        /// inbound capacity may be slightly higher than this.
        ///
        /// This value is not exact. Due to various in-flight changes, feerate changes, and our
        /// counterparty's conflict-avoidance policy, exactly this amount is not likely to be spendable.
        /// However, our counterparty should be able to spend nearly this amount.
        pub inbound_capacity_msat: u64,
        /// The number of required confirmations on the funding transaction before the funding will be
        /// considered "locked". This number is selected by the channel fundee (i.e. us if
        /// [`is_outbound`] is *not* set), and can be selected for inbound channels with
        /// [`ChannelHandshakeConfig::minimum_depth`] or limited for outbound channels with
        /// [`ChannelHandshakeLimits::max_minimum_depth`].
        ///
        /// This value will be `None` for outbound channels until the counterparty accepts the channel.
        ///
        /// [`is_outbound`]: ChannelDetails::is_outbound
        /// [`ChannelHandshakeConfig::minimum_depth`]: crate::util::config::ChannelHandshakeConfig::minimum_depth
        /// [`ChannelHandshakeLimits::max_minimum_depth`]: crate::util::config::ChannelHandshakeLimits::max_minimum_depth
        pub confirmations_required: Option<u32>,
        /// The current number of confirmations on the funding transaction.
        ///
        /// This value will be `None` for objects serialized with LDK versions prior to 0.0.113.
        pub confirmations: Option<u32>,
        /// The number of blocks (after our commitment transaction confirms) that we will need to wait
        /// until we can claim our funds after we force-close the channel. During this time our
        /// counterparty is allowed to punish us if we broadcasted a stale state. If our counterparty
        /// force-closes the channel and broadcasts a commitment transaction we do not have to wait any
        /// time to claim our non-HTLC-encumbered funds.
        ///
        /// This value will be `None` for outbound channels until the counterparty accepts the channel.
        pub force_close_spend_delay: Option<u16>,
        /// True if the channel was initiated (and thus funded) by us.
        pub is_outbound: bool,
        /// True if the channel is confirmed, channel_ready messages have been exchanged, and the
        /// channel is not currently being shut down. `channel_ready` message exchange implies the
        /// required confirmation count has been reached (and we were connected to the peer at some
        /// point after the funding transaction received enough confirmations). The required
        /// confirmation count is provided in [`confirmations_required`].
        ///
        /// [`confirmations_required`]: ChannelDetails::confirmations_required
        pub is_channel_ready: bool,
        /// The stage of the channel's shutdown.
        /// `None` for `ChannelDetails` serialized on LDK versions prior to 0.0.116.
        pub channel_shutdown_state: Option<ChannelShutdownState>,
        /// True if the channel is (a) confirmed and channel_ready messages have been exchanged, (b)
        /// the peer is connected, and (c) the channel is not currently negotiating a shutdown.
        ///
        /// This is a strict superset of `is_channel_ready`.
        pub is_usable: bool,
        /// True if this channel is (or will be) publicly-announced.
        pub is_public: bool,
        /// The smallest value HTLC (in msat) we will accept, for this channel. This field
        /// is only `None` for `ChannelDetails` objects serialized prior to LDK 0.0.107
        pub inbound_htlc_minimum_msat: Option<u64>,
        /// The largest value HTLC (in msat) we currently will accept, for this channel.
        pub inbound_htlc_maximum_msat: Option<u64>,
        /// Set of configurable parameters that affect channel operation.
        ///
        /// This field is only `None` for `ChannelDetails` objects serialized prior to LDK 0.0.109.
        pub config: Option<ChannelConfig>,
}

impl ChannelDetails {
        /// Gets the current SCID which should be used to identify this channel for inbound payments.
        /// This should be used for providing invoice hints or in any other context where our
        /// counterparty will forward a payment to us.
        ///
        /// This is either the [`ChannelDetails::inbound_scid_alias`], if set, or the
        /// [`ChannelDetails::short_channel_id`]. See those for more information.
        pub fn get_inbound_payment_scid(&self) -> Option<u64> {
                self.inbound_scid_alias.or(self.short_channel_id)
        }

        /// Gets the current SCID which should be used to identify this channel for outbound payments.
        /// This should be used in [`Route`]s to describe the first hop or in other contexts where
        /// we're sending or forwarding a payment outbound over this channel.
        ///
        /// This is either the [`ChannelDetails::short_channel_id`], if set, or the
        /// [`ChannelDetails::outbound_scid_alias`]. See those for more information.
        pub fn get_outbound_payment_scid(&self) -> Option<u64> {
                self.short_channel_id.or(self.outbound_scid_alias)
        }

        fn from_channel_context<SP: Deref, F: Deref>(
                context: &ChannelContext<SP>, best_block_height: u32, latest_features: InitFeatures,
                fee_estimator: &LowerBoundedFeeEstimator<F>
        ) -> Self
        where
                SP::Target: SignerProvider,
                F::Target: FeeEstimator
        {
                let balance = context.get_available_balances(fee_estimator);
                let (to_remote_reserve_satoshis, to_self_reserve_satoshis) =
                        context.get_holder_counterparty_selected_channel_reserve_satoshis();
                ChannelDetails {
                        channel_id: context.channel_id(),
                        counterparty: ChannelCounterparty {
                                node_id: context.get_counterparty_node_id(),
                                features: latest_features,
                                unspendable_punishment_reserve: to_remote_reserve_satoshis,
                                forwarding_info: context.counterparty_forwarding_info(),
                                // Ensures that we have actually received the `htlc_minimum_msat` value
                                // from the counterparty through the `OpenChannel` or `AcceptChannel`
                                // message (as they are always the first message from the counterparty).
                                // Else `Channel::get_counterparty_htlc_minimum_msat` could return the
                                // default `0` value set by `Channel::new_outbound`.
                                outbound_htlc_minimum_msat: if context.have_received_message() {
                                        Some(context.get_counterparty_htlc_minimum_msat()) } else { None },
                                outbound_htlc_maximum_msat: context.get_counterparty_htlc_maximum_msat(),
                        },
                        funding_txo: context.get_funding_txo(),
                        // Note that accept_channel (or open_channel) is always the first message, so
                        // `have_received_message` indicates that type negotiation has completed.
                        channel_type: if context.have_received_message() { Some(context.get_channel_type().clone()) } else { None },
                        short_channel_id: context.get_short_channel_id(),
                        outbound_scid_alias: if context.is_usable() { Some(context.outbound_scid_alias()) } else { None },
                        inbound_scid_alias: context.latest_inbound_scid_alias(),
                        channel_value_satoshis: context.get_value_satoshis(),
                        feerate_sat_per_1000_weight: Some(context.get_feerate_sat_per_1000_weight()),
                        unspendable_punishment_reserve: to_self_reserve_satoshis,
                        balance_msat: balance.balance_msat,
                        inbound_capacity_msat: balance.inbound_capacity_msat,
                        outbound_capacity_msat: balance.outbound_capacity_msat,
                        next_outbound_htlc_limit_msat: balance.next_outbound_htlc_limit_msat,
                        next_outbound_htlc_minimum_msat: balance.next_outbound_htlc_minimum_msat,
                        user_channel_id: context.get_user_id(),
                        confirmations_required: context.minimum_depth(),
                        confirmations: Some(context.get_funding_tx_confirmations(best_block_height)),
                        force_close_spend_delay: context.get_counterparty_selected_contest_delay(),
                        is_outbound: context.is_outbound(),
                        is_channel_ready: context.is_usable(),
                        is_usable: context.is_live(),
                        is_public: context.should_announce(),
                        inbound_htlc_minimum_msat: Some(context.get_holder_htlc_minimum_msat()),
                        inbound_htlc_maximum_msat: context.get_holder_htlc_maximum_msat(),
                        config: Some(context.config()),
                        channel_shutdown_state: Some(context.shutdown_state()),
                }
        }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
/// Further information on the details of the channel shutdown.
/// Upon channels being forced closed (i.e. commitment transaction confirmation detected
/// by `ChainMonitor`), ChannelShutdownState will be set to `ShutdownComplete` or
/// the channel will be removed shortly.
/// Also note, that in normal operation, peers could disconnect at any of these states
/// and require peer re-connection before making progress onto other states
pub enum ChannelShutdownState {
        /// Channel has not sent or received a shutdown message.
        NotShuttingDown,
        /// Local node has sent a shutdown message for this channel.
        ShutdownInitiated,
        /// Shutdown message exchanges have concluded and the channels are in the midst of
        /// resolving all existing open HTLCs before closing can continue.
        ResolvingHTLCs,
        /// All HTLCs have been resolved, nodes are currently negotiating channel close onchain fee rates.
        NegotiatingClosingFee,
        /// We've successfully negotiated a closing_signed dance. At this point `ChannelManager` is about
        /// to drop the channel.
        ShutdownComplete,
}

/// Used by [`ChannelManager::list_recent_payments`] to express the status of recent payments.
/// These include payments that have yet to find a successful path, or have unresolved HTLCs.
#[derive(Debug, PartialEq)]
pub enum RecentPaymentDetails {
        /// When an invoice was requested and thus a payment has not yet been sent.
        AwaitingInvoice {
                /// A user-provided identifier in [`ChannelManager::send_payment`] used to uniquely identify
                /// a payment and ensure idempotency in LDK.
                payment_id: PaymentId,
        },
        /// When a payment is still being sent and awaiting successful delivery.
        Pending {
                /// A user-provided identifier in [`ChannelManager::send_payment`] used to uniquely identify
                /// a payment and ensure idempotency in LDK.
                payment_id: PaymentId,
                /// Hash of the payment that is currently being sent but has yet to be fulfilled or
                /// abandoned.
                payment_hash: PaymentHash,
                /// Total amount (in msat, excluding fees) across all paths for this payment,
                /// not just the amount currently inflight.
                total_msat: u64,
        },
        /// When a pending payment is fulfilled, we continue tracking it until all pending HTLCs have
        /// been resolved. Upon receiving [`Event::PaymentSent`], we delay for a few minutes before the
        /// payment is removed from tracking.
        Fulfilled {
                /// A user-provided identifier in [`ChannelManager::send_payment`] used to uniquely identify
                /// a payment and ensure idempotency in LDK.
                payment_id: PaymentId,
                /// Hash of the payment that was claimed. `None` for serializations of [`ChannelManager`]
                /// made before LDK version 0.0.104.
                payment_hash: Option<PaymentHash>,
        },
        /// After a payment's retries are exhausted per the provided [`Retry`], or it is explicitly
        /// abandoned via [`ChannelManager::abandon_payment`], it is marked as abandoned until all
        /// pending HTLCs for this payment resolve and an [`Event::PaymentFailed`] is generated.
        Abandoned {
                /// A user-provided identifier in [`ChannelManager::send_payment`] used to uniquely identify
                /// a payment and ensure idempotency in LDK.
                payment_id: PaymentId,
                /// Hash of the payment that we have given up trying to send.
                payment_hash: PaymentHash,
        },
}

/// Route hints used in constructing invoices for [phantom node payents].
///
/// [phantom node payments]: crate::sign::PhantomKeysManager
#[derive(Clone)]
pub struct PhantomRouteHints {
        /// The list of channels to be included in the invoice route hints.
        pub channels: Vec<ChannelDetails>,
        /// A fake scid used for representing the phantom node's fake channel in generating the invoice
        /// route hints.
        pub phantom_scid: u64,
        /// The pubkey of the real backing node that would ultimately receive the payment.
        pub real_node_pubkey: PublicKey,
}

macro_rules! handle_error {
        ($self: ident, $internal: expr, $counterparty_node_id: expr) => { {
                // In testing, ensure there are no deadlocks where the lock is already held upon
                // entering the macro.
                debug_assert_ne!($self.pending_events.held_by_thread(), LockHeldState::HeldByThread);
                debug_assert_ne!($self.per_peer_state.held_by_thread(), LockHeldState::HeldByThread);

                match $internal {
                        Ok(msg) => Ok(msg),
                        Err(MsgHandleErrInternal { err, chan_id, shutdown_finish, channel_capacity }) => {
                                let mut msg_events = Vec::with_capacity(2);

                                if let Some((shutdown_res, update_option)) = shutdown_finish {
                                        $self.finish_close_channel(shutdown_res);
                                        if let Some(update) = update_option {
                                                msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                        msg: update
                                                });
                                        }
                                        if let Some((channel_id, user_channel_id)) = chan_id {
                                                $self.pending_events.lock().unwrap().push_back((events::Event::ChannelClosed {
                                                        channel_id, user_channel_id,
                                                        reason: ClosureReason::ProcessingError { err: err.err.clone() },
                                                        counterparty_node_id: Some($counterparty_node_id),
                                                        channel_capacity_sats: channel_capacity,
                                                }, None));
                                        }
                                }

                                log_error!($self.logger, "{}", err.err);
                                if let msgs::ErrorAction::IgnoreError = err.action {
                                } else {
                                        msg_events.push(events::MessageSendEvent::HandleError {
                                                node_id: $counterparty_node_id,
                                                action: err.action.clone()
                                        });
                                }

                                if !msg_events.is_empty() {
                                        let per_peer_state = $self.per_peer_state.read().unwrap();
                                        if let Some(peer_state_mutex) = per_peer_state.get(&$counterparty_node_id) {
                                                let mut peer_state = peer_state_mutex.lock().unwrap();
                                                peer_state.pending_msg_events.append(&mut msg_events);
                                        }
                                }

                                // Return error in case higher-API need one
                                Err(err)
                        },
                }
        } };
        ($self: ident, $internal: expr) => {
                match $internal {
                        Ok(res) => Ok(res),
                        Err((chan, msg_handle_err)) => {
                                let counterparty_node_id = chan.get_counterparty_node_id();
                                handle_error!($self, Err(msg_handle_err), counterparty_node_id).map_err(|err| (chan, err))
                        },
                }
        };
}

macro_rules! update_maps_on_chan_removal {
        ($self: expr, $channel_context: expr) => {{
                $self.id_to_peer.lock().unwrap().remove(&$channel_context.channel_id());
                let mut short_to_chan_info = $self.short_to_chan_info.write().unwrap();
                if let Some(short_id) = $channel_context.get_short_channel_id() {
                        short_to_chan_info.remove(&short_id);
                } else {
                        // If the channel was never confirmed on-chain prior to its closure, remove the
                        // outbound SCID alias we used for it from the collision-prevention set. While we
                        // generally want to avoid ever re-using an outbound SCID alias across all channels, we
                        // also don't want a counterparty to be able to trivially cause a memory leak by simply
                        // opening a million channels with us which are closed before we ever reach the funding
                        // stage.
                        let alias_removed = $self.outbound_scid_aliases.lock().unwrap().remove(&$channel_context.outbound_scid_alias());
                        debug_assert!(alias_removed);
                }
                short_to_chan_info.remove(&$channel_context.outbound_scid_alias());
        }}
}

/// Returns (boolean indicating if we should remove the Channel object from memory, a mapped error)
macro_rules! convert_chan_phase_err {
        ($self: ident, $err: expr, $channel: expr, $channel_id: expr, MANUAL_CHANNEL_UPDATE, $channel_update: expr) => {
                match $err {
                        ChannelError::Warn(msg) => {
                                (false, MsgHandleErrInternal::from_chan_no_close(ChannelError::Warn(msg), *$channel_id))
                        },
                        ChannelError::Ignore(msg) => {
                                (false, MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore(msg), *$channel_id))
                        },
                        ChannelError::Close(msg) => {
                                log_error!($self.logger, "Closing channel {} due to close-required error: {}", $channel_id, msg);
                                update_maps_on_chan_removal!($self, $channel.context);
                                let shutdown_res = $channel.context.force_shutdown(true);
                                let user_id = $channel.context.get_user_id();
                                let channel_capacity_satoshis = $channel.context.get_value_satoshis();

                                (true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, user_id,
                                        shutdown_res, $channel_update, channel_capacity_satoshis))
                        },
                }
        };
        ($self: ident, $err: expr, $channel: expr, $channel_id: expr, FUNDED_CHANNEL) => {
                convert_chan_phase_err!($self, $err, $channel, $channel_id, MANUAL_CHANNEL_UPDATE, { $self.get_channel_update_for_broadcast($channel).ok() })
        };
        ($self: ident, $err: expr, $channel: expr, $channel_id: expr, UNFUNDED_CHANNEL) => {
                convert_chan_phase_err!($self, $err, $channel, $channel_id, MANUAL_CHANNEL_UPDATE, None)
        };
        ($self: ident, $err: expr, $channel_phase: expr, $channel_id: expr) => {
                match $channel_phase {
                        ChannelPhase::Funded(channel) => {
                                convert_chan_phase_err!($self, $err, channel, $channel_id, FUNDED_CHANNEL)
                        },
                        ChannelPhase::UnfundedOutboundV1(channel) => {
                                convert_chan_phase_err!($self, $err, channel, $channel_id, UNFUNDED_CHANNEL)
                        },
                        ChannelPhase::UnfundedInboundV1(channel) => {
                                convert_chan_phase_err!($self, $err, channel, $channel_id, UNFUNDED_CHANNEL)
                        },
                }
        };
}

macro_rules! break_chan_phase_entry {
        ($self: ident, $res: expr, $entry: expr) => {
                match $res {
                        Ok(res) => res,
                        Err(e) => {
                                let key = *$entry.key();
                                let (drop, res) = convert_chan_phase_err!($self, e, $entry.get_mut(), &key);
                                if drop {
                                        $entry.remove_entry();
                                }
                                break Err(res);
                        }
                }
        }
}

macro_rules! try_chan_phase_entry {
        ($self: ident, $res: expr, $entry: expr) => {
                match $res {
                        Ok(res) => res,
                        Err(e) => {
                                let key = *$entry.key();
                                let (drop, res) = convert_chan_phase_err!($self, e, $entry.get_mut(), &key);
                                if drop {
                                        $entry.remove_entry();
                                }
                                return Err(res);
                        }
                }
        }
}

macro_rules! remove_channel_phase {
        ($self: expr, $entry: expr) => {
                {
                        let channel = $entry.remove_entry().1;
                        update_maps_on_chan_removal!($self, &channel.context());
                        channel
                }
        }
}

macro_rules! send_channel_ready {
        ($self: ident, $pending_msg_events: expr, $channel: expr, $channel_ready_msg: expr) => {{
                $pending_msg_events.push(events::MessageSendEvent::SendChannelReady {
                        node_id: $channel.context.get_counterparty_node_id(),
                        msg: $channel_ready_msg,
                });
                // Note that we may send a `channel_ready` multiple times for a channel if we reconnect, so
                // we allow collisions, but we shouldn't ever be updating the channel ID pointed to.
                let mut short_to_chan_info = $self.short_to_chan_info.write().unwrap();
                let outbound_alias_insert = short_to_chan_info.insert($channel.context.outbound_scid_alias(), ($channel.context.get_counterparty_node_id(), $channel.context.channel_id()));
                assert!(outbound_alias_insert.is_none() || outbound_alias_insert.unwrap() == ($channel.context.get_counterparty_node_id(), $channel.context.channel_id()),
                        "SCIDs should never collide - ensure you weren't behind the chain tip by a full month when creating channels");
                if let Some(real_scid) = $channel.context.get_short_channel_id() {
                        let scid_insert = short_to_chan_info.insert(real_scid, ($channel.context.get_counterparty_node_id(), $channel.context.channel_id()));
                        assert!(scid_insert.is_none() || scid_insert.unwrap() == ($channel.context.get_counterparty_node_id(), $channel.context.channel_id()),
                                "SCIDs should never collide - ensure you weren't behind the chain tip by a full month when creating channels");
                }
        }}
}

macro_rules! emit_channel_pending_event {
        ($locked_events: expr, $channel: expr) => {
                if $channel.context.should_emit_channel_pending_event() {
                        $locked_events.push_back((events::Event::ChannelPending {
                                channel_id: $channel.context.channel_id(),
                                former_temporary_channel_id: $channel.context.temporary_channel_id(),
                                counterparty_node_id: $channel.context.get_counterparty_node_id(),
                                user_channel_id: $channel.context.get_user_id(),
                                funding_txo: $channel.context.get_funding_txo().unwrap().into_bitcoin_outpoint(),
                        }, None));
                        $channel.context.set_channel_pending_event_emitted();
                }
        }
}

macro_rules! emit_channel_ready_event {
        ($locked_events: expr, $channel: expr) => {
                if $channel.context.should_emit_channel_ready_event() {
                        debug_assert!($channel.context.channel_pending_event_emitted());
                        $locked_events.push_back((events::Event::ChannelReady {
                                channel_id: $channel.context.channel_id(),
                                user_channel_id: $channel.context.get_user_id(),
                                counterparty_node_id: $channel.context.get_counterparty_node_id(),
                                channel_type: $channel.context.get_channel_type().clone(),
                        }, None));
                        $channel.context.set_channel_ready_event_emitted();
                }
        }
}

macro_rules! handle_monitor_update_completion {
        ($self: ident, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr) => { {
                let mut updates = $chan.monitor_updating_restored(&$self.logger,
                        &$self.node_signer, $self.chain_hash, &$self.default_configuration,
                        $self.best_block.read().unwrap().height());
                let counterparty_node_id = $chan.context.get_counterparty_node_id();
                let channel_update = if updates.channel_ready.is_some() && $chan.context.is_usable() {
                        // We only send a channel_update in the case where we are just now sending a
                        // channel_ready and the channel is in a usable state. We may re-send a
                        // channel_update later through the announcement_signatures process for public
                        // channels, but there's no reason not to just inform our counterparty of our fees
                        // now.
                        if let Ok(msg) = $self.get_channel_update_for_unicast($chan) {
                                Some(events::MessageSendEvent::SendChannelUpdate {
                                        node_id: counterparty_node_id,
                                        msg,
                                })
                        } else { None }
                } else { None };

                let update_actions = $peer_state.monitor_update_blocked_actions
                        .remove(&$chan.context.channel_id()).unwrap_or(Vec::new());

                let htlc_forwards = $self.handle_channel_resumption(
                        &mut $peer_state.pending_msg_events, $chan, updates.raa,
                        updates.commitment_update, updates.order, updates.accepted_htlcs,
                        updates.funding_broadcastable, updates.channel_ready,
                        updates.announcement_sigs);
                if let Some(upd) = channel_update {
                        $peer_state.pending_msg_events.push(upd);
                }

                let channel_id = $chan.context.channel_id();
                let unbroadcasted_batch_funding_txid = $chan.context.unbroadcasted_batch_funding_txid();
                core::mem::drop($peer_state_lock);
                core::mem::drop($per_peer_state_lock);

                // If the channel belongs to a batch funding transaction, the progress of the batch
                // should be updated as we have received funding_signed and persisted the monitor.
                if let Some(txid) = unbroadcasted_batch_funding_txid {
                        let mut funding_batch_states = $self.funding_batch_states.lock().unwrap();
                        let mut batch_completed = false;
                        if let Some(batch_state) = funding_batch_states.get_mut(&txid) {
                                let channel_state = batch_state.iter_mut().find(|(chan_id, pubkey, _)| (
                                        *chan_id == channel_id &&
                                        *pubkey == counterparty_node_id
                                ));
                                if let Some(channel_state) = channel_state {
                                        channel_state.2 = true;
                                } else {
                                        debug_assert!(false, "Missing channel batch state for channel which completed initial monitor update");
                                }
                                batch_completed = batch_state.iter().all(|(_, _, completed)| *completed);
                        } else {
                                debug_assert!(false, "Missing batch state for channel which completed initial monitor update");
                        }

                        // When all channels in a batched funding transaction have become ready, it is not necessary
                        // to track the progress of the batch anymore and the state of the channels can be updated.
                        if batch_completed {
                                let removed_batch_state = funding_batch_states.remove(&txid).into_iter().flatten();
                                let per_peer_state = $self.per_peer_state.read().unwrap();
                                let mut batch_funding_tx = None;
                                for (channel_id, counterparty_node_id, _) in removed_batch_state {
                                        if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
                                                let mut peer_state = peer_state_mutex.lock().unwrap();
                                                if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get_mut(&channel_id) {
                                                        batch_funding_tx = batch_funding_tx.or_else(|| chan.context.unbroadcasted_funding());
                                                        chan.set_batch_ready();
                                                        let mut pending_events = $self.pending_events.lock().unwrap();
                                                        emit_channel_pending_event!(pending_events, chan);
                                                }
                                        }
                                }
                                if let Some(tx) = batch_funding_tx {
                                        log_info!($self.logger, "Broadcasting batch funding transaction with txid {}", tx.txid());
                                        $self.tx_broadcaster.broadcast_transactions(&[&tx]);
                                }
                        }
                }

                $self.handle_monitor_update_completion_actions(update_actions);

                if let Some(forwards) = htlc_forwards {
                        $self.forward_htlcs(&mut [forwards][..]);
                }
                $self.finalize_claims(updates.finalized_claimed_htlcs);
                for failure in updates.failed_htlcs.drain(..) {
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id };
                        $self.fail_htlc_backwards_internal(&failure.0, &failure.1, &failure.2, receiver);
                }
        } }
}

macro_rules! handle_new_monitor_update {
        ($self: ident, $update_res: expr, $chan: expr, _internal, $completed: expr) => { {
                debug_assert!($self.background_events_processed_since_startup.load(Ordering::Acquire));
                match $update_res {
                        ChannelMonitorUpdateStatus::UnrecoverableError => {
                                let err_str = "ChannelMonitor[Update] persistence failed unrecoverably. This indicates we cannot continue normal operation and must shut down.";
                                log_error!($self.logger, "{}", err_str);
                                panic!("{}", err_str);
                        },
                        ChannelMonitorUpdateStatus::InProgress => {
                                log_debug!($self.logger, "ChannelMonitor update for {} in flight, holding messages until the update completes.",
                                        &$chan.context.channel_id());
                                false
                        },
                        ChannelMonitorUpdateStatus::Completed => {
                                $completed;
                                true
                        },
                }
        } };
        ($self: ident, $update_res: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr, INITIAL_MONITOR) => {
                handle_new_monitor_update!($self, $update_res, $chan, _internal,
                        handle_monitor_update_completion!($self, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan))
        };
        ($self: ident, $funding_txo: expr, $update: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr) => { {
                let in_flight_updates = $peer_state.in_flight_monitor_updates.entry($funding_txo)
                        .or_insert_with(Vec::new);
                // During startup, we push monitor updates as background events through to here in
                // order to replay updates that were in-flight when we shut down. Thus, we have to
                // filter for uniqueness here.
                let idx = in_flight_updates.iter().position(|upd| upd == &$update)
                        .unwrap_or_else(|| {
                                in_flight_updates.push($update);
                                in_flight_updates.len() - 1
                        });
                let update_res = $self.chain_monitor.update_channel($funding_txo, &in_flight_updates[idx]);
                handle_new_monitor_update!($self, update_res, $chan, _internal,
                        {
                                let _ = in_flight_updates.remove(idx);
                                if in_flight_updates.is_empty() && $chan.blocked_monitor_updates_pending() == 0 {
                                        handle_monitor_update_completion!($self, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan);
                                }
                        })
        } };
}

macro_rules! process_events_body {
        ($self: expr, $event_to_handle: expr, $handle_event: expr) => {
                let mut processed_all_events = false;
                while !processed_all_events {
                        if $self.pending_events_processor.compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed).is_err() {
                                return;
                        }

                        let mut result;

                        {
                                // We'll acquire our total consistency lock so that we can be sure no other
                                // persists happen while processing monitor events.
                                let _read_guard = $self.total_consistency_lock.read().unwrap();

                                // Because `handle_post_event_actions` may send `ChannelMonitorUpdate`s to the user we must
                                // ensure any startup-generated background events are handled first.
                                result = $self.process_background_events();

                                // TODO: This behavior should be documented. It's unintuitive that we query
                                // ChannelMonitors when clearing other events.
                                if $self.process_pending_monitor_events() {
                                        result = NotifyOption::DoPersist;
                                }
                        }

                        let pending_events = $self.pending_events.lock().unwrap().clone();
                        let num_events = pending_events.len();
                        if !pending_events.is_empty() {
                                result = NotifyOption::DoPersist;
                        }

                        let mut post_event_actions = Vec::new();

                        for (event, action_opt) in pending_events {
                                $event_to_handle = event;
                                $handle_event;
                                if let Some(action) = action_opt {
                                        post_event_actions.push(action);
                                }
                        }

                        {
                                let mut pending_events = $self.pending_events.lock().unwrap();
                                pending_events.drain(..num_events);
                                processed_all_events = pending_events.is_empty();
                                // Note that `push_pending_forwards_ev` relies on `pending_events_processor` being
                                // updated here with the `pending_events` lock acquired.
                                $self.pending_events_processor.store(false, Ordering::Release);
                        }

                        if !post_event_actions.is_empty() {
                                $self.handle_post_event_actions(post_event_actions);
                                // If we had some actions, go around again as we may have more events now
                                processed_all_events = false;
                        }

                        match result {
                                NotifyOption::DoPersist => {
                                        $self.needs_persist_flag.store(true, Ordering::Release);
                                        $self.event_persist_notifier.notify();
                                },
                                NotifyOption::SkipPersistHandleEvents =>
                                        $self.event_persist_notifier.notify(),
                                NotifyOption::SkipPersistNoEvents => {},
                        }
                }
        }
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        /// Constructs a new `ChannelManager` to hold several channels and route between them.
        ///
        /// The current time or latest block header time can be provided as the `current_timestamp`.
        ///
        /// This is the main "logic hub" for all channel-related actions, and implements
        /// [`ChannelMessageHandler`].
        ///
        /// Non-proportional fees are fixed according to our risk using the provided fee estimator.
        ///
        /// Users need to notify the new `ChannelManager` when a new block is connected or
        /// disconnected using its [`block_connected`] and [`block_disconnected`] methods, starting
        /// from after [`params.best_block.block_hash`]. See [`chain::Listen`] and [`chain::Confirm`] for
        /// more details.
        ///
        /// [`block_connected`]: chain::Listen::block_connected
        /// [`block_disconnected`]: chain::Listen::block_disconnected
        /// [`params.best_block.block_hash`]: chain::BestBlock::block_hash
        pub fn new(
                fee_est: F, chain_monitor: M, tx_broadcaster: T, router: R, logger: L, entropy_source: ES,
                node_signer: NS, signer_provider: SP, config: UserConfig, params: ChainParameters,
                current_timestamp: u32,
        ) -> Self {
                let mut secp_ctx = Secp256k1::new();
                secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
                let inbound_pmt_key_material = node_signer.get_inbound_payment_key_material();
                let expanded_inbound_key = inbound_payment::ExpandedKey::new(&inbound_pmt_key_material);
                ChannelManager {
                        default_configuration: config.clone(),
                        chain_hash: ChainHash::using_genesis_block(params.network),
                        fee_estimator: LowerBoundedFeeEstimator::new(fee_est),
                        chain_monitor,
                        tx_broadcaster,
                        router,

                        best_block: RwLock::new(params.best_block),

                        outbound_scid_aliases: Mutex::new(HashSet::new()),
                        pending_inbound_payments: Mutex::new(HashMap::new()),
                        pending_outbound_payments: OutboundPayments::new(),
                        forward_htlcs: Mutex::new(HashMap::new()),
                        claimable_payments: Mutex::new(ClaimablePayments { claimable_payments: HashMap::new(), pending_claiming_payments: HashMap::new() }),
                        pending_intercepted_htlcs: Mutex::new(HashMap::new()),
                        id_to_peer: Mutex::new(HashMap::new()),
                        short_to_chan_info: FairRwLock::new(HashMap::new()),

                        our_network_pubkey: node_signer.get_node_id(Recipient::Node).unwrap(),
                        secp_ctx,

                        inbound_payment_key: expanded_inbound_key,
                        fake_scid_rand_bytes: entropy_source.get_secure_random_bytes(),

                        probing_cookie_secret: entropy_source.get_secure_random_bytes(),

                        highest_seen_timestamp: AtomicUsize::new(current_timestamp as usize),

                        per_peer_state: FairRwLock::new(HashMap::new()),

                        pending_events: Mutex::new(VecDeque::new()),
                        pending_events_processor: AtomicBool::new(false),
                        pending_background_events: Mutex::new(Vec::new()),
                        total_consistency_lock: RwLock::new(()),
                        background_events_processed_since_startup: AtomicBool::new(false),
                        event_persist_notifier: Notifier::new(),
                        needs_persist_flag: AtomicBool::new(false),
                        funding_batch_states: Mutex::new(BTreeMap::new()),

                        pending_offers_messages: Mutex::new(Vec::new()),

                        entropy_source,
                        node_signer,
                        signer_provider,

                        logger,
                }
        }

        /// Gets the current configuration applied to all new channels.
        pub fn get_current_default_configuration(&self) -> &UserConfig {
                &self.default_configuration
        }

        fn create_and_insert_outbound_scid_alias(&self) -> u64 {
                let height = self.best_block.read().unwrap().height();
                let mut outbound_scid_alias = 0;
                let mut i = 0;
                loop {
                        if cfg!(fuzzing) { // fuzzing chacha20 doesn't use the key at all so we always get the same alias
                                outbound_scid_alias += 1;
                        } else {
                                outbound_scid_alias = fake_scid::Namespace::OutboundAlias.get_fake_scid(height, &self.chain_hash, &self.fake_scid_rand_bytes, &self.entropy_source);
                        }
                        if outbound_scid_alias != 0 && self.outbound_scid_aliases.lock().unwrap().insert(outbound_scid_alias) {
                                break;
                        }
                        i += 1;
                        if i > 1_000_000 { panic!("Your RNG is busted or we ran out of possible outbound SCID aliases (which should never happen before we run out of memory to store channels"); }
                }
                outbound_scid_alias
        }

        /// Creates a new outbound channel to the given remote node and with the given value.
        ///
        /// `user_channel_id` will be provided back as in
        /// [`Event::FundingGenerationReady::user_channel_id`] to allow tracking of which events
        /// correspond with which `create_channel` call. Note that the `user_channel_id` defaults to a
        /// randomized value for inbound channels. `user_channel_id` has no meaning inside of LDK, it
        /// is simply copied to events and otherwise ignored.
        ///
        /// Raises [`APIError::APIMisuseError`] when `channel_value_satoshis` > 2**24 or `push_msat` is
        /// greater than `channel_value_satoshis * 1k` or `channel_value_satoshis < 1000`.
        ///
        /// Raises [`APIError::ChannelUnavailable`] if the channel cannot be opened due to failing to
        /// generate a shutdown scriptpubkey or destination script set by
        /// [`SignerProvider::get_shutdown_scriptpubkey`] or [`SignerProvider::get_destination_script`].
        ///
        /// Note that we do not check if you are currently connected to the given peer. If no
        /// connection is available, the outbound `open_channel` message may fail to send, resulting in
        /// the channel eventually being silently forgotten (dropped on reload).
        ///
        /// If `temporary_channel_id` is specified, it will be used as the temporary channel ID of the
        /// channel. Otherwise, a random one will be generated for you.
        ///
        /// Returns the new Channel's temporary `channel_id`. This ID will appear as
        /// [`Event::FundingGenerationReady::temporary_channel_id`] and in
        /// [`ChannelDetails::channel_id`] until after
        /// [`ChannelManager::funding_transaction_generated`] is called, swapping the Channel's ID for
        /// one derived from the funding transaction's TXID. If the counterparty rejects the channel
        /// immediately, this temporary ID will appear in [`Event::ChannelClosed::channel_id`].
        ///
        /// [`Event::FundingGenerationReady::user_channel_id`]: events::Event::FundingGenerationReady::user_channel_id
        /// [`Event::FundingGenerationReady::temporary_channel_id`]: events::Event::FundingGenerationReady::temporary_channel_id
        /// [`Event::ChannelClosed::channel_id`]: events::Event::ChannelClosed::channel_id
        pub fn create_channel(&self, their_network_key: PublicKey, channel_value_satoshis: u64, push_msat: u64, user_channel_id: u128, temporary_channel_id: Option<ChannelId>, override_config: Option<UserConfig>) -> Result<ChannelId, APIError> {
                if channel_value_satoshis < 1000 {
                        return Err(APIError::APIMisuseError { err: format!("Channel value must be at least 1000 satoshis. It was {}", channel_value_satoshis) });
                }

                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                // We want to make sure the lock is actually acquired by PersistenceNotifierGuard.
                debug_assert!(&self.total_consistency_lock.try_write().is_err());

                let per_peer_state = self.per_peer_state.read().unwrap();

                let peer_state_mutex = per_peer_state.get(&their_network_key)
                        .ok_or_else(|| APIError::APIMisuseError{ err: format!("Not connected to node: {}", their_network_key) })?;

                let mut peer_state = peer_state_mutex.lock().unwrap();

                if let Some(temporary_channel_id) = temporary_channel_id {
                        if peer_state.channel_by_id.contains_key(&temporary_channel_id) {
                                return Err(APIError::APIMisuseError{ err: format!("Channel with temporary channel ID {} already exists!", temporary_channel_id)});
                        }
                }

                let channel = {
                        let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                        let their_features = &peer_state.latest_features;
                        let config = if override_config.is_some() { override_config.as_ref().unwrap() } else { &self.default_configuration };
                        match OutboundV1Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider, their_network_key,
                                their_features, channel_value_satoshis, push_msat, user_channel_id, config,
                                self.best_block.read().unwrap().height(), outbound_scid_alias, temporary_channel_id)
                        {
                                Ok(res) => res,
                                Err(e) => {
                                        self.outbound_scid_aliases.lock().unwrap().remove(&outbound_scid_alias);
                                        return Err(e);
                                },
                        }
                };
                let res = channel.get_open_channel(self.chain_hash);

                let temporary_channel_id = channel.context.channel_id();
                match peer_state.channel_by_id.entry(temporary_channel_id) {
                        hash_map::Entry::Occupied(_) => {
                                if cfg!(fuzzing) {
                                        return Err(APIError::APIMisuseError { err: "Fuzzy bad RNG".to_owned() });
                                } else {
                                        panic!("RNG is bad???");
                                }
                        },
                        hash_map::Entry::Vacant(entry) => { entry.insert(ChannelPhase::UnfundedOutboundV1(channel)); }
                }

                peer_state.pending_msg_events.push(events::MessageSendEvent::SendOpenChannel {
                        node_id: their_network_key,
                        msg: res,
                });
                Ok(temporary_channel_id)
        }

        fn list_funded_channels_with_filter<Fn: FnMut(&(&ChannelId, &Channel<SP>)) -> bool + Copy>(&self, f: Fn) -> Vec<ChannelDetails> {
                // Allocate our best estimate of the number of channels we have in the `res`
                // Vec. Sadly the `short_to_chan_info` map doesn't cover channels without
                // a scid or a scid alias, and the `id_to_peer` shouldn't be used outside
                // of the ChannelMonitor handling. Therefore reallocations may still occur, but is
                // unlikely as the `short_to_chan_info` map often contains 2 entries for
                // the same channel.
                let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
                {
                        let best_block_height = self.best_block.read().unwrap().height();
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                res.extend(peer_state.channel_by_id.iter()
                                        .filter_map(|(chan_id, phase)| match phase {
                                                // Only `Channels` in the `ChannelPhase::Funded` phase can be considered funded.
                                                ChannelPhase::Funded(chan) => Some((chan_id, chan)),
                                                _ => None,
                                        })
                                        .filter(f)
                                        .map(|(_channel_id, channel)| {
                                                ChannelDetails::from_channel_context(&channel.context, best_block_height,
                                                        peer_state.latest_features.clone(), &self.fee_estimator)
                                        })
                                );
                        }
                }
                res
        }

        /// Gets the list of open channels, in random order. See [`ChannelDetails`] field documentation for
        /// more information.
        pub fn list_channels(&self) -> Vec<ChannelDetails> {
                // Allocate our best estimate of the number of channels we have in the `res`
                // Vec. Sadly the `short_to_chan_info` map doesn't cover channels without
                // a scid or a scid alias, and the `id_to_peer` shouldn't be used outside
                // of the ChannelMonitor handling. Therefore reallocations may still occur, but is
                // unlikely as the `short_to_chan_info` map often contains 2 entries for
                // the same channel.
                let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
                {
                        let best_block_height = self.best_block.read().unwrap().height();
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                for context in peer_state.channel_by_id.iter().map(|(_, phase)| phase.context()) {
                                        let details = ChannelDetails::from_channel_context(context, best_block_height,
                                                peer_state.latest_features.clone(), &self.fee_estimator);
                                        res.push(details);
                                }
                        }
                }
                res
        }

        /// Gets the list of usable channels, in random order. Useful as an argument to
        /// [`Router::find_route`] to ensure non-announced channels are used.
        ///
        /// These are guaranteed to have their [`ChannelDetails::is_usable`] value set to true, see the
        /// documentation for [`ChannelDetails::is_usable`] for more info on exactly what the criteria
        /// are.
        pub fn list_usable_channels(&self) -> Vec<ChannelDetails> {
                // Note we use is_live here instead of usable which leads to somewhat confused
                // internal/external nomenclature, but that's ok cause that's probably what the user
                // really wanted anyway.
                self.list_funded_channels_with_filter(|&(_, ref channel)| channel.context.is_live())
        }

        /// Gets the list of channels we have with a given counterparty, in random order.
        pub fn list_channels_with_counterparty(&self, counterparty_node_id: &PublicKey) -> Vec<ChannelDetails> {
                let best_block_height = self.best_block.read().unwrap().height();
                let per_peer_state = self.per_peer_state.read().unwrap();

                if let Some(peer_state_mutex) = per_peer_state.get(counterparty_node_id) {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        let features = &peer_state.latest_features;
                        let context_to_details = |context| {
                                ChannelDetails::from_channel_context(context, best_block_height, features.clone(), &self.fee_estimator)
                        };
                        return peer_state.channel_by_id
                                .iter()
                                .map(|(_, phase)| phase.context())
                                .map(context_to_details)
                                .collect();
                }
                vec![]
        }

        /// Returns in an undefined order recent payments that -- if not fulfilled -- have yet to find a
        /// successful path, or have unresolved HTLCs.
        ///
        /// This can be useful for payments that may have been prepared, but ultimately not sent, as a
        /// result of a crash. If such a payment exists, is not listed here, and an
        /// [`Event::PaymentSent`] has not been received, you may consider resending the payment.
        ///
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        pub fn list_recent_payments(&self) -> Vec<RecentPaymentDetails> {
                self.pending_outbound_payments.pending_outbound_payments.lock().unwrap().iter()
                        .filter_map(|(payment_id, pending_outbound_payment)| match pending_outbound_payment {
                                PendingOutboundPayment::AwaitingInvoice { .. } => {
                                        Some(RecentPaymentDetails::AwaitingInvoice { payment_id: *payment_id })
                                },
                                // InvoiceReceived is an intermediate state and doesn't need to be exposed
                                PendingOutboundPayment::InvoiceReceived { .. } => {
                                        Some(RecentPaymentDetails::AwaitingInvoice { payment_id: *payment_id })
                                },
                                PendingOutboundPayment::Retryable { payment_hash, total_msat, .. } => {
                                        Some(RecentPaymentDetails::Pending {
                                                payment_id: *payment_id,
                                                payment_hash: *payment_hash,
                                                total_msat: *total_msat,
                                        })
                                },
                                PendingOutboundPayment::Abandoned { payment_hash, .. } => {
                                        Some(RecentPaymentDetails::Abandoned { payment_id: *payment_id, payment_hash: *payment_hash })
                                },
                                PendingOutboundPayment::Fulfilled { payment_hash, .. } => {
                                        Some(RecentPaymentDetails::Fulfilled { payment_id: *payment_id, payment_hash: *payment_hash })
                                },
                                PendingOutboundPayment::Legacy { .. } => None
                        })
                        .collect()
        }

        /// Helper function that issues the channel close events
        fn issue_channel_close_events(&self, context: &ChannelContext<SP>, closure_reason: ClosureReason) {
                let mut pending_events_lock = self.pending_events.lock().unwrap();
                match context.unbroadcasted_funding() {
                        Some(transaction) => {
                                pending_events_lock.push_back((events::Event::DiscardFunding {
                                        channel_id: context.channel_id(), transaction
                                }, None));
                        },
                        None => {},
                }
                pending_events_lock.push_back((events::Event::ChannelClosed {
                        channel_id: context.channel_id(),
                        user_channel_id: context.get_user_id(),
                        reason: closure_reason,
                        counterparty_node_id: Some(context.get_counterparty_node_id()),
                        channel_capacity_sats: Some(context.get_value_satoshis()),
                }, None));
        }

        fn close_channel_internal(&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey, target_feerate_sats_per_1000_weight: Option<u32>, override_shutdown_script: Option<ShutdownScript>) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let mut failed_htlcs: Vec<(HTLCSource, PaymentHash)>;
                let shutdown_result;
                loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();

                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                                .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;

                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;

                        match peer_state.channel_by_id.entry(channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                        if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                                let funding_txo_opt = chan.context.get_funding_txo();
                                                let their_features = &peer_state.latest_features;
                                                let (shutdown_msg, mut monitor_update_opt, htlcs, local_shutdown_result) =
                                                        chan.get_shutdown(&self.signer_provider, their_features, target_feerate_sats_per_1000_weight, override_shutdown_script)?;
                                                failed_htlcs = htlcs;
                                                shutdown_result = local_shutdown_result;
                                                debug_assert_eq!(shutdown_result.is_some(), chan.is_shutdown());

                                                // We can send the `shutdown` message before updating the `ChannelMonitor`
                                                // here as we don't need the monitor update to complete until we send a
                                                // `shutdown_signed`, which we'll delay if we're pending a monitor update.
                                                peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                        node_id: *counterparty_node_id,
                                                        msg: shutdown_msg,
                                                });

                                                debug_assert!(monitor_update_opt.is_none() || !chan.is_shutdown(),
                                                        "We can't both complete shutdown and generate a monitor update");

                                                // Update the monitor with the shutdown script if necessary.
                                                if let Some(monitor_update) = monitor_update_opt.take() {
                                                        handle_new_monitor_update!(self, funding_txo_opt.unwrap(), monitor_update,
                                                                peer_state_lock, peer_state, per_peer_state, chan);
                                                        break;
                                                }

                                                if chan.is_shutdown() {
                                                        if let ChannelPhase::Funded(chan) = remove_channel_phase!(self, chan_phase_entry) {
                                                                if let Ok(channel_update) = self.get_channel_update_for_broadcast(&chan) {
                                                                        peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                msg: channel_update
                                                                        });
                                                                }
                                                                self.issue_channel_close_events(&chan.context, ClosureReason::HolderForceClosed);
                                                        }
                                                }
                                                break;
                                        }
                                },
                                hash_map::Entry::Vacant(_) => {
                                        // If we reach this point, it means that the channel_id either refers to an unfunded channel or
                                        // it does not exist for this peer. Either way, we can attempt to force-close it.
                                        //
                                        // An appropriate error will be returned for non-existence of the channel if that's the case.
                                        mem::drop(peer_state_lock);
                                        mem::drop(per_peer_state);
                                        return self.force_close_channel_with_peer(&channel_id, counterparty_node_id, None, false).map(|_| ())
                                },
                        }
                }

                for htlc_source in failed_htlcs.drain(..) {
                        let reason = HTLCFailReason::from_failure_code(0x4000 | 8);
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(*counterparty_node_id), channel_id: *channel_id };
                        self.fail_htlc_backwards_internal(&htlc_source.0, &htlc_source.1, &reason, receiver);
                }

                if let Some(shutdown_result) = shutdown_result {
                        self.finish_close_channel(shutdown_result);
                }

                Ok(())
        }

        /// Begins the process of closing a channel. After this call (plus some timeout), no new HTLCs
        /// will be accepted on the given channel, and after additional timeout/the closing of all
        /// pending HTLCs, the channel will be closed on chain.
        ///
        ///  * If we are the channel initiator, we will pay between our [`ChannelCloseMinimum`] and
        ///    [`ChannelConfig::force_close_avoidance_max_fee_satoshis`] plus our [`NonAnchorChannelFee`]
        ///    fee estimate.
        ///  * If our counterparty is the channel initiator, we will require a channel closing
        ///    transaction feerate of at least our [`ChannelCloseMinimum`] feerate or the feerate which
        ///    would appear on a force-closure transaction, whichever is lower. We will allow our
        ///    counterparty to pay as much fee as they'd like, however.
        ///
        /// May generate a [`SendShutdown`] message event on success, which should be relayed.
        ///
        /// Raises [`APIError::ChannelUnavailable`] if the channel cannot be closed due to failing to
        /// generate a shutdown scriptpubkey or destination script set by
        /// [`SignerProvider::get_shutdown_scriptpubkey`]. A force-closure may be needed to close the
        /// channel.
        ///
        /// [`ChannelConfig::force_close_avoidance_max_fee_satoshis`]: crate::util::config::ChannelConfig::force_close_avoidance_max_fee_satoshis
        /// [`ChannelCloseMinimum`]: crate::chain::chaininterface::ConfirmationTarget::ChannelCloseMinimum
        /// [`NonAnchorChannelFee`]: crate::chain::chaininterface::ConfirmationTarget::NonAnchorChannelFee
        /// [`SendShutdown`]: crate::events::MessageSendEvent::SendShutdown
        pub fn close_channel(&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey) -> Result<(), APIError> {
                self.close_channel_internal(channel_id, counterparty_node_id, None, None)
        }

        /// Begins the process of closing a channel. After this call (plus some timeout), no new HTLCs
        /// will be accepted on the given channel, and after additional timeout/the closing of all
        /// pending HTLCs, the channel will be closed on chain.
        ///
        /// `target_feerate_sat_per_1000_weight` has different meanings depending on if we initiated
        /// the channel being closed or not:
        ///  * If we are the channel initiator, we will pay at least this feerate on the closing
        ///    transaction. The upper-bound is set by
        ///    [`ChannelConfig::force_close_avoidance_max_fee_satoshis`] plus our [`NonAnchorChannelFee`]
        ///    fee estimate (or `target_feerate_sat_per_1000_weight`, if it is greater).
        ///  * If our counterparty is the channel initiator, we will refuse to accept a channel closure
        ///    transaction feerate below `target_feerate_sat_per_1000_weight` (or the feerate which
        ///    will appear on a force-closure transaction, whichever is lower).
        ///
        /// The `shutdown_script` provided  will be used as the `scriptPubKey` for the closing transaction.
        /// Will fail if a shutdown script has already been set for this channel by
        /// ['ChannelHandshakeConfig::commit_upfront_shutdown_pubkey`]. The given shutdown script must
        /// also be compatible with our and the counterparty's features.
        ///
        /// May generate a [`SendShutdown`] message event on success, which should be relayed.
        ///
        /// Raises [`APIError::ChannelUnavailable`] if the channel cannot be closed due to failing to
        /// generate a shutdown scriptpubkey or destination script set by
        /// [`SignerProvider::get_shutdown_scriptpubkey`]. A force-closure may be needed to close the
        /// channel.
        ///
        /// [`ChannelConfig::force_close_avoidance_max_fee_satoshis`]: crate::util::config::ChannelConfig::force_close_avoidance_max_fee_satoshis
        /// [`NonAnchorChannelFee`]: crate::chain::chaininterface::ConfirmationTarget::NonAnchorChannelFee
        /// [`SendShutdown`]: crate::events::MessageSendEvent::SendShutdown
        pub fn close_channel_with_feerate_and_script(&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey, target_feerate_sats_per_1000_weight: Option<u32>, shutdown_script: Option<ShutdownScript>) -> Result<(), APIError> {
                self.close_channel_internal(channel_id, counterparty_node_id, target_feerate_sats_per_1000_weight, shutdown_script)
        }

        fn finish_close_channel(&self, mut shutdown_res: ShutdownResult) {
                debug_assert_ne!(self.per_peer_state.held_by_thread(), LockHeldState::HeldByThread);
                #[cfg(debug_assertions)]
                for (_, peer) in self.per_peer_state.read().unwrap().iter() {
                        debug_assert_ne!(peer.held_by_thread(), LockHeldState::HeldByThread);
                }

                log_debug!(self.logger, "Finishing closure of channel with {} HTLCs to fail", shutdown_res.dropped_outbound_htlcs.len());
                for htlc_source in shutdown_res.dropped_outbound_htlcs.drain(..) {
                        let (source, payment_hash, counterparty_node_id, channel_id) = htlc_source;
                        let reason = HTLCFailReason::from_failure_code(0x4000 | 8);
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id };
                        self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
                }
                if let Some((_, funding_txo, monitor_update)) = shutdown_res.monitor_update {
                        // There isn't anything we can do if we get an update failure - we're already
                        // force-closing. The monitor update on the required in-memory copy should broadcast
                        // the latest local state, which is the best we can do anyway. Thus, it is safe to
                        // ignore the result here.
                        let _ = self.chain_monitor.update_channel(funding_txo, &monitor_update);
                }
                let mut shutdown_results = Vec::new();
                if let Some(txid) = shutdown_res.unbroadcasted_batch_funding_txid {
                        let mut funding_batch_states = self.funding_batch_states.lock().unwrap();
                        let affected_channels = funding_batch_states.remove(&txid).into_iter().flatten();
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let mut has_uncompleted_channel = None;
                        for (channel_id, counterparty_node_id, state) in affected_channels {
                                if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
                                        let mut peer_state = peer_state_mutex.lock().unwrap();
                                        if let Some(mut chan) = peer_state.channel_by_id.remove(&channel_id) {
                                                update_maps_on_chan_removal!(self, &chan.context());
                                                self.issue_channel_close_events(&chan.context(), ClosureReason::FundingBatchClosure);
                                                shutdown_results.push(chan.context_mut().force_shutdown(false));
                                        }
                                }
                                has_uncompleted_channel = Some(has_uncompleted_channel.map_or(!state, |v| v || !state));
                        }
                        debug_assert!(
                                has_uncompleted_channel.unwrap_or(true),
                                "Closing a batch where all channels have completed initial monitor update",
                        );
                }
                for shutdown_result in shutdown_results.drain(..) {
                        self.finish_close_channel(shutdown_result);
                }
        }

        /// `peer_msg` should be set when we receive a message from a peer, but not set when the
        /// user closes, which will be re-exposed as the `ChannelClosed` reason.
        fn force_close_channel_with_peer(&self, channel_id: &ChannelId, peer_node_id: &PublicKey, peer_msg: Option<&String>, broadcast: bool)
        -> Result<PublicKey, APIError> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(peer_node_id)
                        .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", peer_node_id) })?;
                let (update_opt, counterparty_node_id) = {
                        let mut peer_state = peer_state_mutex.lock().unwrap();
                        let closure_reason = if let Some(peer_msg) = peer_msg {
                                ClosureReason::CounterpartyForceClosed { peer_msg: UntrustedString(peer_msg.to_string()) }
                        } else {
                                ClosureReason::HolderForceClosed
                        };
                        if let hash_map::Entry::Occupied(chan_phase_entry) = peer_state.channel_by_id.entry(channel_id.clone()) {
                                log_error!(self.logger, "Force-closing channel {}", channel_id);
                                self.issue_channel_close_events(&chan_phase_entry.get().context(), closure_reason);
                                let mut chan_phase = remove_channel_phase!(self, chan_phase_entry);
                                mem::drop(peer_state);
                                mem::drop(per_peer_state);
                                match chan_phase {
                                        ChannelPhase::Funded(mut chan) => {
                                                self.finish_close_channel(chan.context.force_shutdown(broadcast));
                                                (self.get_channel_update_for_broadcast(&chan).ok(), chan.context.get_counterparty_node_id())
                                        },
                                        ChannelPhase::UnfundedOutboundV1(_) | ChannelPhase::UnfundedInboundV1(_) => {
                                                self.finish_close_channel(chan_phase.context_mut().force_shutdown(false));
                                                // Unfunded channel has no update
                                                (None, chan_phase.context().get_counterparty_node_id())
                                        },
                                }
                        } else if peer_state.inbound_channel_request_by_id.remove(channel_id).is_some() {
                                log_error!(self.logger, "Force-closing channel {}", &channel_id);
                                // N.B. that we don't send any channel close event here: we
                                // don't have a user_channel_id, and we never sent any opening
                                // events anyway.
                                (None, *peer_node_id)
                        } else {
                                return Err(APIError::ChannelUnavailable{ err: format!("Channel with id {} not found for the passed counterparty node_id {}", channel_id, peer_node_id) });
                        }
                };
                if let Some(update) = update_opt {
                        // Try to send the `BroadcastChannelUpdate` to the peer we just force-closed on, but if
                        // not try to broadcast it via whatever peer we have.
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let a_peer_state_opt = per_peer_state.get(peer_node_id)
                                .ok_or(per_peer_state.values().next());
                        if let Ok(a_peer_state_mutex) = a_peer_state_opt {
                                let mut a_peer_state = a_peer_state_mutex.lock().unwrap();
                                a_peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                        msg: update
                                });
                        }
                }

                Ok(counterparty_node_id)
        }

        fn force_close_sending_error(&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey, broadcast: bool) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                match self.force_close_channel_with_peer(channel_id, counterparty_node_id, None, broadcast) {
                        Ok(counterparty_node_id) => {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
                                        let mut peer_state = peer_state_mutex.lock().unwrap();
                                        peer_state.pending_msg_events.push(
                                                events::MessageSendEvent::HandleError {
                                                        node_id: counterparty_node_id,
                                                        action: msgs::ErrorAction::DisconnectPeer {
                                                                msg: Some(msgs::ErrorMessage { channel_id: *channel_id, data: "Channel force-closed".to_owned() })
                                                        },
                                                }
                                        );
                                }
                                Ok(())
                        },
                        Err(e) => Err(e)
                }
        }

        /// Force closes a channel, immediately broadcasting the latest local transaction(s) and
        /// rejecting new HTLCs on the given channel. Fails if `channel_id` is unknown to
        /// the manager, or if the `counterparty_node_id` isn't the counterparty of the corresponding
        /// channel.
        pub fn force_close_broadcasting_latest_txn(&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey)
        -> Result<(), APIError> {
                self.force_close_sending_error(channel_id, counterparty_node_id, true)
        }

        /// Force closes a channel, rejecting new HTLCs on the given channel but skips broadcasting
        /// the latest local transaction(s). Fails if `channel_id` is unknown to the manager, or if the
        /// `counterparty_node_id` isn't the counterparty of the corresponding channel.
        ///
        /// You can always get the latest local transaction(s) to broadcast from
        /// [`ChannelMonitor::get_latest_holder_commitment_txn`].
        pub fn force_close_without_broadcasting_txn(&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey)
        -> Result<(), APIError> {
                self.force_close_sending_error(channel_id, counterparty_node_id, false)
        }

        /// Force close all channels, immediately broadcasting the latest local commitment transaction
        /// for each to the chain and rejecting new HTLCs on each.
        pub fn force_close_all_channels_broadcasting_latest_txn(&self) {
                for chan in self.list_channels() {
                        let _ = self.force_close_broadcasting_latest_txn(&chan.channel_id, &chan.counterparty.node_id);
                }
        }

        /// Force close all channels rejecting new HTLCs on each but without broadcasting the latest
        /// local transaction(s).
        pub fn force_close_all_channels_without_broadcasting_txn(&self) {
                for chan in self.list_channels() {
                        let _ = self.force_close_without_broadcasting_txn(&chan.channel_id, &chan.counterparty.node_id);
                }
        }

        fn decode_update_add_htlc_onion(
                &self, msg: &msgs::UpdateAddHTLC
        ) -> Result<
                (onion_utils::Hop, [u8; 32], Option<Result<PublicKey, secp256k1::Error>>), HTLCFailureMsg
        > {
                let (next_hop, shared_secret, next_packet_details_opt) = decode_incoming_update_add_htlc_onion(
                        msg, &self.node_signer, &self.logger, &self.secp_ctx
                )?;

                macro_rules! return_err {
                        ($msg: expr, $err_code: expr, $data: expr) => {
                                {
                                        log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                        return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
                                                channel_id: msg.channel_id,
                                                htlc_id: msg.htlc_id,
                                                reason: HTLCFailReason::reason($err_code, $data.to_vec())
                                                        .get_encrypted_failure_packet(&shared_secret, &None),
                                        }));
                                }
                        }
                }

                let NextPacketDetails {
                        next_packet_pubkey, outgoing_amt_msat, outgoing_scid, outgoing_cltv_value
                } = match next_packet_details_opt {
                        Some(next_packet_details) => next_packet_details,
                        // it is a receive, so no need for outbound checks
                        None => return Ok((next_hop, shared_secret, None)),
                };

                // Perform outbound checks here instead of in [`Self::construct_pending_htlc_info`] because we
                // can't hold the outbound peer state lock at the same time as the inbound peer state lock.
                if let Some((err, mut code, chan_update)) = loop {
                        let id_option = self.short_to_chan_info.read().unwrap().get(&outgoing_scid).cloned();
                        let forwarding_chan_info_opt = match id_option {
                                None => { // unknown_next_peer
                                        // Note that this is likely a timing oracle for detecting whether an scid is a
                                        // phantom or an intercept.
                                        if (self.default_configuration.accept_intercept_htlcs &&
                                                fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
                                                fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
                                        {
                                                None
                                        } else {
                                                break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
                                        }
                                },
                                Some((cp_id, id)) => Some((cp_id.clone(), id.clone())),
                        };
                        let chan_update_opt = if let Some((counterparty_node_id, forwarding_id)) = forwarding_chan_info_opt {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
                                if peer_state_mutex_opt.is_none() {
                                        break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
                                }
                                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                let chan = match peer_state.channel_by_id.get_mut(&forwarding_id).map(
                                        |chan_phase| if let ChannelPhase::Funded(chan) = chan_phase { Some(chan) } else { None }
                                ).flatten() {
                                        None => {
                                                // Channel was removed. The short_to_chan_info and channel_by_id maps
                                                // have no consistency guarantees.
                                                break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
                                        },
                                        Some(chan) => chan
                                };
                                if !chan.context.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels {
                                        // Note that the behavior here should be identical to the above block - we
                                        // should NOT reveal the existence or non-existence of a private channel if
                                        // we don't allow forwards outbound over them.
                                        break Some(("Refusing to forward to a private channel based on our config.", 0x4000 | 10, None));
                                }
                                if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
                                        // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
                                        // "refuse to forward unless the SCID alias was used", so we pretend
                                        // we don't have the channel here.
                                        break Some(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10, None));
                                }
                                let chan_update_opt = self.get_channel_update_for_onion(outgoing_scid, chan).ok();

                                // Note that we could technically not return an error yet here and just hope
                                // that the connection is reestablished or monitor updated by the time we get
                                // around to doing the actual forward, but better to fail early if we can and
                                // hopefully an attacker trying to path-trace payments cannot make this occur
                                // on a small/per-node/per-channel scale.
                                if !chan.context.is_live() { // channel_disabled
                                        // If the channel_update we're going to return is disabled (i.e. the
                                        // peer has been disabled for some time), return `channel_disabled`,
                                        // otherwise return `temporary_channel_failure`.
                                        if chan_update_opt.as_ref().map(|u| u.contents.flags & 2 == 2).unwrap_or(false) {
                                                break Some(("Forwarding channel has been disconnected for some time.", 0x1000 | 20, chan_update_opt));
                                        } else {
                                                break Some(("Forwarding channel is not in a ready state.", 0x1000 | 7, chan_update_opt));
                                        }
                                }
                                if outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
                                        break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt));
                                }
                                if let Err((err, code)) = chan.htlc_satisfies_config(&msg, outgoing_amt_msat, outgoing_cltv_value) {
                                        break Some((err, code, chan_update_opt));
                                }
                                chan_update_opt
                        } else {
                                None
                        };

                        let cur_height = self.best_block.read().unwrap().height() + 1;

                        if let Err((err_msg, code)) = check_incoming_htlc_cltv(
                                cur_height, outgoing_cltv_value, msg.cltv_expiry
                        ) {
                                if code & 0x1000 != 0 && chan_update_opt.is_none() {
                                        // We really should set `incorrect_cltv_expiry` here but as we're not
                                        // forwarding over a real channel we can't generate a channel_update
                                        // for it. Instead we just return a generic temporary_node_failure.
                                        break Some((err_msg, 0x2000 | 2, None))
                                }
                                let chan_update_opt = if code & 0x1000 != 0 { chan_update_opt } else { None };
                                break Some((err_msg, code, chan_update_opt));
                        }

                        break None;
                }
                {
                        let mut res = VecWriter(Vec::with_capacity(chan_update.serialized_length() + 2 + 8 + 2));
                        if let Some(chan_update) = chan_update {
                                if code == 0x1000 | 11 || code == 0x1000 | 12 {
                                        msg.amount_msat.write(&mut res).expect("Writes cannot fail");
                                }
                                else if code == 0x1000 | 13 {
                                        msg.cltv_expiry.write(&mut res).expect("Writes cannot fail");
                                }
                                else if code == 0x1000 | 20 {
                                        // TODO: underspecified, follow https://github.com/lightning/bolts/issues/791
                                        0u16.write(&mut res).expect("Writes cannot fail");
                                }
                                (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
                                msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
                                chan_update.write(&mut res).expect("Writes cannot fail");
                        } else if code & 0x1000 == 0x1000 {
                                // If we're trying to return an error that requires a `channel_update` but
                                // we're forwarding to a phantom or intercept "channel" (i.e. cannot
                                // generate an update), just use the generic "temporary_node_failure"
                                // instead.
                                code = 0x2000 | 2;
                        }
                        return_err!(err, code, &res.0[..]);
                }
                Ok((next_hop, shared_secret, Some(next_packet_pubkey)))
        }

        fn construct_pending_htlc_status<'a>(
                &self, msg: &msgs::UpdateAddHTLC, shared_secret: [u8; 32], decoded_hop: onion_utils::Hop,
                allow_underpay: bool, next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
        ) -> PendingHTLCStatus {
                macro_rules! return_err {
                        ($msg: expr, $err_code: expr, $data: expr) => {
                                {
                                        log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                        return PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
                                                channel_id: msg.channel_id,
                                                htlc_id: msg.htlc_id,
                                                reason: HTLCFailReason::reason($err_code, $data.to_vec())
                                                        .get_encrypted_failure_packet(&shared_secret, &None),
                                        }));
                                }
                        }
                }
                match decoded_hop {
                        onion_utils::Hop::Receive(next_hop_data) => {
                                // OUR PAYMENT!
                                let current_height: u32 = self.best_block.read().unwrap().height();
                                match create_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash,
                                        msg.amount_msat, msg.cltv_expiry, None, allow_underpay, msg.skimmed_fee_msat,
                                        current_height, self.default_configuration.accept_mpp_keysend)
                                {
                                        Ok(info) => {
                                                // Note that we could obviously respond immediately with an update_fulfill_htlc
                                                // message, however that would leak that we are the recipient of this payment, so
                                                // instead we stay symmetric with the forwarding case, only responding (after a
                                                // delay) once they've send us a commitment_signed!
                                                PendingHTLCStatus::Forward(info)
                                        },
                                        Err(InboundOnionErr { err_code, err_data, msg }) => return_err!(msg, err_code, &err_data)
                                }
                        },
                        onion_utils::Hop::Forward { next_hop_data, next_hop_hmac, new_packet_bytes } => {
                                match create_fwd_pending_htlc_info(msg, next_hop_data, next_hop_hmac,
                                        new_packet_bytes, shared_secret, next_packet_pubkey_opt) {
                                        Ok(info) => PendingHTLCStatus::Forward(info),
                                        Err(InboundOnionErr { err_code, err_data, msg }) => return_err!(msg, err_code, &err_data)
                                }
                        }
                }
        }

        /// Gets the current [`channel_update`] for the given channel. This first checks if the channel is
        /// public, and thus should be called whenever the result is going to be passed out in a
        /// [`MessageSendEvent::BroadcastChannelUpdate`] event.
        ///
        /// Note that in [`internal_closing_signed`], this function is called without the `peer_state`
        /// corresponding to the channel's counterparty locked, as the channel been removed from the
        /// storage and the `peer_state` lock has been dropped.
        ///
        /// [`channel_update`]: msgs::ChannelUpdate
        /// [`internal_closing_signed`]: Self::internal_closing_signed
        fn get_channel_update_for_broadcast(&self, chan: &Channel<SP>) -> Result<msgs::ChannelUpdate, LightningError> {
                if !chan.context.should_announce() {
                        return Err(LightningError {
                                err: "Cannot broadcast a channel_update for a private channel".to_owned(),
                                action: msgs::ErrorAction::IgnoreError
                        });
                }
                if chan.context.get_short_channel_id().is_none() {
                        return Err(LightningError{err: "Channel not yet established".to_owned(), action: msgs::ErrorAction::IgnoreError});
                }
                log_trace!(self.logger, "Attempting to generate broadcast channel update for channel {}", &chan.context.channel_id());
                self.get_channel_update_for_unicast(chan)
        }

        /// Gets the current [`channel_update`] for the given channel. This does not check if the channel
        /// is public (only returning an `Err` if the channel does not yet have an assigned SCID),
        /// and thus MUST NOT be called unless the recipient of the resulting message has already
        /// provided evidence that they know about the existence of the channel.
        ///
        /// Note that through [`internal_closing_signed`], this function is called without the
        /// `peer_state`  corresponding to the channel's counterparty locked, as the channel been
        /// removed from the storage and the `peer_state` lock has been dropped.
        ///
        /// [`channel_update`]: msgs::ChannelUpdate
        /// [`internal_closing_signed`]: Self::internal_closing_signed
        fn get_channel_update_for_unicast(&self, chan: &Channel<SP>) -> Result<msgs::ChannelUpdate, LightningError> {
                log_trace!(self.logger, "Attempting to generate channel update for channel {}", &chan.context.channel_id());
                let short_channel_id = match chan.context.get_short_channel_id().or(chan.context.latest_inbound_scid_alias()) {
                        None => return Err(LightningError{err: "Channel not yet established".to_owned(), action: msgs::ErrorAction::IgnoreError}),
                        Some(id) => id,
                };

                self.get_channel_update_for_onion(short_channel_id, chan)
        }

        fn get_channel_update_for_onion(&self, short_channel_id: u64, chan: &Channel<SP>) -> Result<msgs::ChannelUpdate, LightningError> {
                log_trace!(self.logger, "Generating channel update for channel {}", &chan.context.channel_id());
                let were_node_one = self.our_network_pubkey.serialize()[..] < chan.context.get_counterparty_node_id().serialize()[..];

                let enabled = chan.context.is_usable() && match chan.channel_update_status() {
                        ChannelUpdateStatus::Enabled => true,
                        ChannelUpdateStatus::DisabledStaged(_) => true,
                        ChannelUpdateStatus::Disabled => false,
                        ChannelUpdateStatus::EnabledStaged(_) => false,
                };

                let unsigned = msgs::UnsignedChannelUpdate {
                        chain_hash: self.chain_hash,
                        short_channel_id,
                        timestamp: chan.context.get_update_time_counter(),
                        flags: (!were_node_one) as u8 | ((!enabled as u8) << 1),
                        cltv_expiry_delta: chan.context.get_cltv_expiry_delta(),
                        htlc_minimum_msat: chan.context.get_counterparty_htlc_minimum_msat(),
                        htlc_maximum_msat: chan.context.get_announced_htlc_max_msat(),
                        fee_base_msat: chan.context.get_outbound_forwarding_fee_base_msat(),
                        fee_proportional_millionths: chan.context.get_fee_proportional_millionths(),
                        excess_data: Vec::new(),
                };
                // Panic on failure to signal LDK should be restarted to retry signing the `ChannelUpdate`.
                // If we returned an error and the `node_signer` cannot provide a signature for whatever
                // reason`, we wouldn't be able to receive inbound payments through the corresponding
                // channel.
                let sig = self.node_signer.sign_gossip_message(msgs::UnsignedGossipMessage::ChannelUpdate(&unsigned)).unwrap();

                Ok(msgs::ChannelUpdate {
                        signature: sig,
                        contents: unsigned
                })
        }

        #[cfg(test)]
        pub(crate) fn test_send_payment_along_path(&self, path: &Path, payment_hash: &PaymentHash, recipient_onion: RecipientOnionFields, total_value: u64, cur_height: u32, payment_id: PaymentId, keysend_preimage: &Option<PaymentPreimage>, session_priv_bytes: [u8; 32]) -> Result<(), APIError> {
                let _lck = self.total_consistency_lock.read().unwrap();
                self.send_payment_along_path(SendAlongPathArgs {
                        path, payment_hash, recipient_onion, total_value, cur_height, payment_id, keysend_preimage,
                        session_priv_bytes
                })
        }

        fn send_payment_along_path(&self, args: SendAlongPathArgs) -> Result<(), APIError> {
                let SendAlongPathArgs {
                        path, payment_hash, recipient_onion, total_value, cur_height, payment_id, keysend_preimage,
                        session_priv_bytes
                } = args;
                // The top-level caller should hold the total_consistency_lock read lock.
                debug_assert!(self.total_consistency_lock.try_write().is_err());

                log_trace!(self.logger,
                        "Attempting to send payment with payment hash {} along path with next hop {}",
                        payment_hash, path.hops.first().unwrap().short_channel_id);
                let prng_seed = self.entropy_source.get_secure_random_bytes();
                let session_priv = SecretKey::from_slice(&session_priv_bytes[..]).expect("RNG is busted");

                let (onion_packet, htlc_msat, htlc_cltv) = onion_utils::create_payment_onion(
                        &self.secp_ctx, &path, &session_priv, total_value, recipient_onion, cur_height,
                        payment_hash, keysend_preimage, prng_seed
                )?;

                let err: Result<(), _> = loop {
                        let (counterparty_node_id, id) = match self.short_to_chan_info.read().unwrap().get(&path.hops.first().unwrap().short_channel_id) {
                                None => return Err(APIError::ChannelUnavailable{err: "No channel available with first hop!".to_owned()}),
                                Some((cp_id, chan_id)) => (cp_id.clone(), chan_id.clone()),
                        };

                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(&counterparty_node_id)
                                .ok_or_else(|| APIError::ChannelUnavailable{err: "No peer matching the path's first hop found!".to_owned() })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        if let hash_map::Entry::Occupied(mut chan_phase_entry) = peer_state.channel_by_id.entry(id) {
                                match chan_phase_entry.get_mut() {
                                        ChannelPhase::Funded(chan) => {
                                                if !chan.context.is_live() {
                                                        return Err(APIError::ChannelUnavailable{err: "Peer for first hop currently disconnected".to_owned()});
                                                }
                                                let funding_txo = chan.context.get_funding_txo().unwrap();
                                                let send_res = chan.send_htlc_and_commit(htlc_msat, payment_hash.clone(),
                                                        htlc_cltv, HTLCSource::OutboundRoute {
                                                                path: path.clone(),
                                                                session_priv: session_priv.clone(),
                                                                first_hop_htlc_msat: htlc_msat,
                                                                payment_id,
                                                        }, onion_packet, None, &self.fee_estimator, &self.logger);
                                                match break_chan_phase_entry!(self, send_res, chan_phase_entry) {
                                                        Some(monitor_update) => {
                                                                match handle_new_monitor_update!(self, funding_txo, monitor_update, peer_state_lock, peer_state, per_peer_state, chan) {
                                                                        false => {
                                                                                // Note that MonitorUpdateInProgress here indicates (per function
                                                                                // docs) that we will resend the commitment update once monitor
                                                                                // updating completes. Therefore, we must return an error
                                                                                // indicating that it is unsafe to retry the payment wholesale,
                                                                                // which we do in the send_payment check for
                                                                                // MonitorUpdateInProgress, below.
                                                                                return Err(APIError::MonitorUpdateInProgress);
                                                                        },
                                                                        true => {},
                                                                }
                                                        },
                                                        None => {},
                                                }
                                        },
                                        _ => return Err(APIError::ChannelUnavailable{err: "Channel to first hop is unfunded".to_owned()}),
                                };
                        } else {
                                // The channel was likely removed after we fetched the id from the
                                // `short_to_chan_info` map, but before we successfully locked the
                                // `channel_by_id` map.
                                // This can occur as no consistency guarantees exists between the two maps.
                                return Err(APIError::ChannelUnavailable{err: "No channel available with first hop!".to_owned()});
                        }
                        return Ok(());
                };

                match handle_error!(self, err, path.hops.first().unwrap().pubkey) {
                        Ok(_) => unreachable!(),
                        Err(e) => {
                                Err(APIError::ChannelUnavailable { err: e.err })
                        },
                }
        }

        /// Sends a payment along a given route.
        ///
        /// Value parameters are provided via the last hop in route, see documentation for [`RouteHop`]
        /// fields for more info.
        ///
        /// May generate [`UpdateHTLCs`] message(s) event on success, which should be relayed (e.g. via
        /// [`PeerManager::process_events`]).
        ///
        /// # Avoiding Duplicate Payments
        ///
        /// If a pending payment is currently in-flight with the same [`PaymentId`] provided, this
        /// method will error with an [`APIError::InvalidRoute`]. Note, however, that once a payment
        /// is no longer pending (either via [`ChannelManager::abandon_payment`], or handling of an
        /// [`Event::PaymentSent`] or [`Event::PaymentFailed`]) LDK will not stop you from sending a
        /// second payment with the same [`PaymentId`].
        ///
        /// Thus, in order to ensure duplicate payments are not sent, you should implement your own
        /// tracking of payments, including state to indicate once a payment has completed. Because you
        /// should also ensure that [`PaymentHash`]es are not re-used, for simplicity, you should
        /// consider using the [`PaymentHash`] as the key for tracking payments. In that case, the
        /// [`PaymentId`] should be a copy of the [`PaymentHash`] bytes.
        ///
        /// Additionally, in the scenario where we begin the process of sending a payment, but crash
        /// before `send_payment` returns (or prior to [`ChannelMonitorUpdate`] persistence if you're
        /// using [`ChannelMonitorUpdateStatus::InProgress`]), the payment may be lost on restart. See
        /// [`ChannelManager::list_recent_payments`] for more information.
        ///
        /// # Possible Error States on [`PaymentSendFailure`]
        ///
        /// Each path may have a different return value, and [`PaymentSendFailure`] may return a `Vec` with
        /// each entry matching the corresponding-index entry in the route paths, see
        /// [`PaymentSendFailure`] for more info.
        ///
        /// In general, a path may raise:
        ///  * [`APIError::InvalidRoute`] when an invalid route or forwarding parameter (cltv_delta, fee,
        ///    node public key) is specified.
        ///  * [`APIError::ChannelUnavailable`] if the next-hop channel is not available as it has been
        ///    closed, doesn't exist, or the peer is currently disconnected.
        ///  * [`APIError::MonitorUpdateInProgress`] if a new monitor update failure prevented sending the
        ///    relevant updates.
        ///
        /// Note that depending on the type of the [`PaymentSendFailure`] the HTLC may have been
        /// irrevocably committed to on our end. In such a case, do NOT retry the payment with a
        /// different route unless you intend to pay twice!
        ///
        /// [`RouteHop`]: crate::routing::router::RouteHop
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        /// [`Event::PaymentFailed`]: events::Event::PaymentFailed
        /// [`UpdateHTLCs`]: events::MessageSendEvent::UpdateHTLCs
        /// [`PeerManager::process_events`]: crate::ln::peer_handler::PeerManager::process_events
        /// [`ChannelMonitorUpdateStatus::InProgress`]: crate::chain::ChannelMonitorUpdateStatus::InProgress
        pub fn send_payment_with_route(&self, route: &Route, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments
                        .send_payment_with_route(route, payment_hash, recipient_onion, payment_id,
                                &self.entropy_source, &self.node_signer, best_block_height,
                                |args| self.send_payment_along_path(args))
        }

        /// Similar to [`ChannelManager::send_payment_with_route`], but will automatically find a route based on
        /// `route_params` and retry failed payment paths based on `retry_strategy`.
        pub fn send_payment(&self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<(), RetryableSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments
                        .send_payment(payment_hash, recipient_onion, payment_id, retry_strategy, route_params,
                                &self.router, self.list_usable_channels(), || self.compute_inflight_htlcs(),
                                &self.entropy_source, &self.node_signer, best_block_height, &self.logger,
                                &self.pending_events, |args| self.send_payment_along_path(args))
        }

        #[cfg(test)]
        pub(super) fn test_send_payment_internal(&self, route: &Route, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, keysend_preimage: Option<PaymentPreimage>, payment_id: PaymentId, recv_value_msat: Option<u64>, onion_session_privs: Vec<[u8; 32]>) -> Result<(), PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.test_send_payment_internal(route, payment_hash, recipient_onion,
                        keysend_preimage, payment_id, recv_value_msat, onion_session_privs, &self.node_signer,
                        best_block_height, |args| self.send_payment_along_path(args))
        }

        #[cfg(test)]
        pub(crate) fn test_add_new_pending_payment(&self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId, route: &Route) -> Result<Vec<[u8; 32]>, PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments.test_add_new_pending_payment(payment_hash, recipient_onion, payment_id, route, None, &self.entropy_source, best_block_height)
        }

        #[cfg(test)]
        pub(crate) fn test_set_payment_metadata(&self, payment_id: PaymentId, new_payment_metadata: Option<Vec<u8>>) {
                self.pending_outbound_payments.test_set_payment_metadata(payment_id, new_payment_metadata);
        }

        pub(super) fn send_payment_for_bolt12_invoice(&self, invoice: &Bolt12Invoice, payment_id: PaymentId) -> Result<(), Bolt12PaymentError> {
                let best_block_height = self.best_block.read().unwrap().height();
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments
                        .send_payment_for_bolt12_invoice(
                                invoice, payment_id, &self.router, self.list_usable_channels(),
                                || self.compute_inflight_htlcs(), &self.entropy_source, &self.node_signer,
                                best_block_height, &self.logger, &self.pending_events,
                                |args| self.send_payment_along_path(args)
                        )
        }

        /// Signals that no further attempts for the given payment should occur. Useful if you have a
        /// pending outbound payment with retries remaining, but wish to stop retrying the payment before
        /// retries are exhausted.
        ///
        /// # Event Generation
        ///
        /// If no [`Event::PaymentFailed`] event had been generated before, one will be generated as soon
        /// as there are no remaining pending HTLCs for this payment.
        ///
        /// Note that calling this method does *not* prevent a payment from succeeding. You must still
        /// wait until you receive either a [`Event::PaymentFailed`] or [`Event::PaymentSent`] event to
        /// determine the ultimate status of a payment.
        ///
        /// # Requested Invoices
        ///
        /// In the case of paying a [`Bolt12Invoice`] via [`ChannelManager::pay_for_offer`], abandoning
        /// the payment prior to receiving the invoice will result in an [`Event::InvoiceRequestFailed`]
        /// and prevent any attempts at paying it once received. The other events may only be generated
        /// once the invoice has been received.
        ///
        /// # Restart Behavior
        ///
        /// If an [`Event::PaymentFailed`] is generated and we restart without first persisting the
        /// [`ChannelManager`], another [`Event::PaymentFailed`] may be generated; likewise for
        /// [`Event::InvoiceRequestFailed`].
        ///
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        pub fn abandon_payment(&self, payment_id: PaymentId) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.abandon_payment(payment_id, PaymentFailureReason::UserAbandoned, &self.pending_events);
        }

        /// Send a spontaneous payment, which is a payment that does not require the recipient to have
        /// generated an invoice. Optionally, you may specify the preimage. If you do choose to specify
        /// the preimage, it must be a cryptographically secure random value that no intermediate node
        /// would be able to guess -- otherwise, an intermediate node may claim the payment and it will
        /// never reach the recipient.
        ///
        /// See [`send_payment`] documentation for more details on the return value of this function
        /// and idempotency guarantees provided by the [`PaymentId`] key.
        ///
        /// Similar to regular payments, you MUST NOT reuse a `payment_preimage` value. See
        /// [`send_payment`] for more information about the risks of duplicate preimage usage.
        ///
        /// [`send_payment`]: Self::send_payment
        pub fn send_spontaneous_payment(&self, route: &Route, payment_preimage: Option<PaymentPreimage>, recipient_onion: RecipientOnionFields, payment_id: PaymentId) -> Result<PaymentHash, PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.send_spontaneous_payment_with_route(
                        route, payment_preimage, recipient_onion, payment_id, &self.entropy_source,
                        &self.node_signer, best_block_height, |args| self.send_payment_along_path(args))
        }

        /// Similar to [`ChannelManager::send_spontaneous_payment`], but will automatically find a route
        /// based on `route_params` and retry failed payment paths based on `retry_strategy`.
        ///
        /// See [`PaymentParameters::for_keysend`] for help in constructing `route_params` for spontaneous
        /// payments.
        ///
        /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
        pub fn send_spontaneous_payment_with_retry(&self, payment_preimage: Option<PaymentPreimage>, recipient_onion: RecipientOnionFields, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<PaymentHash, RetryableSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.send_spontaneous_payment(payment_preimage, recipient_onion,
                        payment_id, retry_strategy, route_params, &self.router, self.list_usable_channels(),
                        || self.compute_inflight_htlcs(),  &self.entropy_source, &self.node_signer, best_block_height,
                        &self.logger, &self.pending_events, |args| self.send_payment_along_path(args))
        }

        /// Send a payment that is probing the given route for liquidity. We calculate the
        /// [`PaymentHash`] of probes based on a static secret and a random [`PaymentId`], which allows
        /// us to easily discern them from real payments.
        pub fn send_probe(&self, path: Path) -> Result<(PaymentHash, PaymentId), PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.send_probe(path, self.probing_cookie_secret,
                        &self.entropy_source, &self.node_signer, best_block_height,
                        |args| self.send_payment_along_path(args))
        }

        /// Returns whether a payment with the given [`PaymentHash`] and [`PaymentId`] is, in fact, a
        /// payment probe.
        #[cfg(test)]
        pub(crate) fn payment_is_probe(&self, payment_hash: &PaymentHash, payment_id: &PaymentId) -> bool {
                outbound_payment::payment_is_probe(payment_hash, payment_id, self.probing_cookie_secret)
        }

        /// Sends payment probes over all paths of a route that would be used to pay the given
        /// amount to the given `node_id`.
        ///
        /// See [`ChannelManager::send_preflight_probes`] for more information.
        pub fn send_spontaneous_preflight_probes(
                &self, node_id: PublicKey, amount_msat: u64, final_cltv_expiry_delta: u32,
                liquidity_limit_multiplier: Option<u64>,
        ) -> Result<Vec<(PaymentHash, PaymentId)>, ProbeSendFailure> {
                let payment_params =
                        PaymentParameters::from_node_id(node_id, final_cltv_expiry_delta);

                let route_params = RouteParameters::from_payment_params_and_value(payment_params, amount_msat);

                self.send_preflight_probes(route_params, liquidity_limit_multiplier)
        }

        /// Sends payment probes over all paths of a route that would be used to pay a route found
        /// according to the given [`RouteParameters`].
        ///
        /// This may be used to send "pre-flight" probes, i.e., to train our scorer before conducting
        /// the actual payment. Note this is only useful if there likely is sufficient time for the
        /// probe to settle before sending out the actual payment, e.g., when waiting for user
        /// confirmation in a wallet UI.
        ///
        /// Otherwise, there is a chance the probe could take up some liquidity needed to complete the
        /// actual payment. Users should therefore be cautious and might avoid sending probes if
        /// liquidity is scarce and/or they don't expect the probe to return before they send the
        /// payment. To mitigate this issue, channels with available liquidity less than the required
        /// amount times the given `liquidity_limit_multiplier` won't be used to send pre-flight
        /// probes. If `None` is given as `liquidity_limit_multiplier`, it defaults to `3`.
        pub fn send_preflight_probes(
                &self, route_params: RouteParameters, liquidity_limit_multiplier: Option<u64>,
        ) -> Result<Vec<(PaymentHash, PaymentId)>, ProbeSendFailure> {
                let liquidity_limit_multiplier = liquidity_limit_multiplier.unwrap_or(3);

                let payer = self.get_our_node_id();
                let usable_channels = self.list_usable_channels();
                let first_hops = usable_channels.iter().collect::<Vec<_>>();
                let inflight_htlcs = self.compute_inflight_htlcs();

                let route = self
                        .router
                        .find_route(&payer, &route_params, Some(&first_hops), inflight_htlcs)
                        .map_err(|e| {
                                log_error!(self.logger, "Failed to find path for payment probe: {:?}", e);
                                ProbeSendFailure::RouteNotFound
                        })?;

                let mut used_liquidity_map = HashMap::with_capacity(first_hops.len());

                let mut res = Vec::new();

                for mut path in route.paths {
                        // If the last hop is probably an unannounced channel we refrain from probing all the
                        // way through to the end and instead probe up to the second-to-last channel.
                        while let Some(last_path_hop) = path.hops.last() {
                                if last_path_hop.maybe_announced_channel {
                                        // We found a potentially announced last hop.
                                        break;
                                } else {
                                        // Drop the last hop, as it's likely unannounced.
                                        log_debug!(
                                                self.logger,
                                                "Avoided sending payment probe all the way to last hop {} as it is likely unannounced.",
                                                last_path_hop.short_channel_id
                                        );
                                        let final_value_msat = path.final_value_msat();
                                        path.hops.pop();
                                        if let Some(new_last) = path.hops.last_mut() {
                                                new_last.fee_msat += final_value_msat;
                                        }
                                }
                        }

                        if path.hops.len() < 2 {
                                log_debug!(
                                        self.logger,
                                        "Skipped sending payment probe over path with less than two hops."
                                );
                                continue;
                        }

                        if let Some(first_path_hop) = path.hops.first() {
                                if let Some(first_hop) = first_hops.iter().find(|h| {
                                        h.get_outbound_payment_scid() == Some(first_path_hop.short_channel_id)
                                }) {
                                        let path_value = path.final_value_msat() + path.fee_msat();
                                        let used_liquidity =
                                                used_liquidity_map.entry(first_path_hop.short_channel_id).or_insert(0);

                                        if first_hop.next_outbound_htlc_limit_msat
                                                < (*used_liquidity + path_value) * liquidity_limit_multiplier
                                        {
                                                log_debug!(self.logger, "Skipped sending payment probe to avoid putting channel {} under the liquidity limit.", first_path_hop.short_channel_id);
                                                continue;
                                        } else {
                                                *used_liquidity += path_value;
                                        }
                                }
                        }

                        res.push(self.send_probe(path).map_err(|e| {
                                log_error!(self.logger, "Failed to send pre-flight probe: {:?}", e);
                                ProbeSendFailure::SendingFailed(e)
                        })?);
                }

                Ok(res)
        }

        /// Handles the generation of a funding transaction, optionally (for tests) with a function
        /// which checks the correctness of the funding transaction given the associated channel.
        fn funding_transaction_generated_intern<FundingOutput: FnMut(&OutboundV1Channel<SP>, &Transaction) -> Result<OutPoint, APIError>>(
                &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, funding_transaction: Transaction, is_batch_funding: bool,
                mut find_funding_output: FundingOutput,
        ) -> Result<(), APIError> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;

                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                let (chan, msg_opt) = match peer_state.channel_by_id.remove(temporary_channel_id) {
                        Some(ChannelPhase::UnfundedOutboundV1(chan)) => {
                                let funding_txo = find_funding_output(&chan, &funding_transaction)?;

                                let funding_res = chan.get_funding_created(funding_transaction, funding_txo, is_batch_funding, &self.logger)
                                        .map_err(|(mut chan, e)| if let ChannelError::Close(msg) = e {
                                                let channel_id = chan.context.channel_id();
                                                let user_id = chan.context.get_user_id();
                                                let shutdown_res = chan.context.force_shutdown(false);
                                                let channel_capacity = chan.context.get_value_satoshis();
                                                (chan, MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, user_id, shutdown_res, None, channel_capacity))
                                        } else { unreachable!(); });
                                match funding_res {
                                        Ok((chan, funding_msg)) => (chan, funding_msg),
                                        Err((chan, err)) => {
                                                mem::drop(peer_state_lock);
                                                mem::drop(per_peer_state);

                                                let _: Result<(), _> = handle_error!(self, Err(err), chan.context.get_counterparty_node_id());
                                                return Err(APIError::ChannelUnavailable {
                                                        err: "Signer refused to sign the initial commitment transaction".to_owned()
                                                });
                                        },
                                }
                        },
                        Some(phase) => {
                                peer_state.channel_by_id.insert(*temporary_channel_id, phase);
                                return Err(APIError::APIMisuseError {
                                        err: format!(
                                                "Channel with id {} for the passed counterparty node_id {} is not an unfunded, outbound V1 channel",
                                                temporary_channel_id, counterparty_node_id),
                                })
                        },
                        None => return Err(APIError::ChannelUnavailable {err: format!(
                                "Channel with id {} not found for the passed counterparty node_id {}",
                                temporary_channel_id, counterparty_node_id),
                                }),
                };

                if let Some(msg) = msg_opt {
                        peer_state.pending_msg_events.push(events::MessageSendEvent::SendFundingCreated {
                                node_id: chan.context.get_counterparty_node_id(),
                                msg,
                        });
                }
                match peer_state.channel_by_id.entry(chan.context.channel_id()) {
                        hash_map::Entry::Occupied(_) => {
                                panic!("Generated duplicate funding txid?");
                        },
                        hash_map::Entry::Vacant(e) => {
                                let mut id_to_peer = self.id_to_peer.lock().unwrap();
                                if id_to_peer.insert(chan.context.channel_id(), chan.context.get_counterparty_node_id()).is_some() {
                                        panic!("id_to_peer map already contained funding txid, which shouldn't be possible");
                                }
                                e.insert(ChannelPhase::Funded(chan));
                        }
                }
                Ok(())
        }

        #[cfg(test)]
        pub(crate) fn funding_transaction_generated_unchecked(&self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, funding_transaction: Transaction, output_index: u16) -> Result<(), APIError> {
                self.funding_transaction_generated_intern(temporary_channel_id, counterparty_node_id, funding_transaction, false, |_, tx| {
                        Ok(OutPoint { txid: tx.txid(), index: output_index })
                })
        }

        /// Call this upon creation of a funding transaction for the given channel.
        ///
        /// Returns an [`APIError::APIMisuseError`] if the funding_transaction spent non-SegWit outputs
        /// or if no output was found which matches the parameters in [`Event::FundingGenerationReady`].
        ///
        /// Returns [`APIError::APIMisuseError`] if the funding transaction is not final for propagation
        /// across the p2p network.
        ///
        /// Returns [`APIError::ChannelUnavailable`] if a funding transaction has already been provided
        /// for the channel or if the channel has been closed as indicated by [`Event::ChannelClosed`].
        ///
        /// May panic if the output found in the funding transaction is duplicative with some other
        /// channel (note that this should be trivially prevented by using unique funding transaction
        /// keys per-channel).
        ///
        /// Do NOT broadcast the funding transaction yourself. When we have safely received our
        /// counterparty's signature the funding transaction will automatically be broadcast via the
        /// [`BroadcasterInterface`] provided when this `ChannelManager` was constructed.
        ///
        /// Note that this includes RBF or similar transaction replacement strategies - lightning does
        /// not currently support replacing a funding transaction on an existing channel. Instead,
        /// create a new channel with a conflicting funding transaction.
        ///
        /// Note to keep the miner incentives aligned in moving the blockchain forward, we recommend
        /// the wallet software generating the funding transaction to apply anti-fee sniping as
        /// implemented by Bitcoin Core wallet. See <https://bitcoinops.org/en/topics/fee-sniping/>
        /// for more details.
        ///
        /// [`Event::FundingGenerationReady`]: crate::events::Event::FundingGenerationReady
        /// [`Event::ChannelClosed`]: crate::events::Event::ChannelClosed
        pub fn funding_transaction_generated(&self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, funding_transaction: Transaction) -> Result<(), APIError> {
                self.batch_funding_transaction_generated(&[(temporary_channel_id, counterparty_node_id)], funding_transaction)
        }

        /// Call this upon creation of a batch funding transaction for the given channels.
        ///
        /// Return values are identical to [`Self::funding_transaction_generated`], respective to
        /// each individual channel and transaction output.
        ///
        /// Do NOT broadcast the funding transaction yourself. This batch funding transaction
        /// will only be broadcast when we have safely received and persisted the counterparty's
        /// signature for each channel.
        ///
        /// If there is an error, all channels in the batch are to be considered closed.
        pub fn batch_funding_transaction_generated(&self, temporary_channels: &[(&ChannelId, &PublicKey)], funding_transaction: Transaction) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let mut result = Ok(());

                if !funding_transaction.is_coin_base() {
                        for inp in funding_transaction.input.iter() {
                                if inp.witness.is_empty() {
                                        result = result.and(Err(APIError::APIMisuseError {
                                                err: "Funding transaction must be fully signed and spend Segwit outputs".to_owned()
                                        }));
                                }
                        }
                }
                if funding_transaction.output.len() > u16::max_value() as usize {
                        result = result.and(Err(APIError::APIMisuseError {
                                err: "Transaction had more than 2^16 outputs, which is not supported".to_owned()
                        }));
                }
                {
                        let height = self.best_block.read().unwrap().height();
                        // Transactions are evaluated as final by network mempools if their locktime is strictly
                        // lower than the next block height. However, the modules constituting our Lightning
                        // node might not have perfect sync about their blockchain views. Thus, if the wallet
                        // module is ahead of LDK, only allow one more block of headroom.
                        if !funding_transaction.input.iter().all(|input| input.sequence == Sequence::MAX) &&
                                funding_transaction.lock_time.is_block_height() &&
                                funding_transaction.lock_time.to_consensus_u32() > height + 1
                        {
                                result = result.and(Err(APIError::APIMisuseError {
                                        err: "Funding transaction absolute timelock is non-final".to_owned()
                                }));
                        }
                }

                let txid = funding_transaction.txid();
                let is_batch_funding = temporary_channels.len() > 1;
                let mut funding_batch_states = if is_batch_funding {
                        Some(self.funding_batch_states.lock().unwrap())
                } else {
                        None
                };
                let mut funding_batch_state = funding_batch_states.as_mut().and_then(|states| {
                        match states.entry(txid) {
                                btree_map::Entry::Occupied(_) => {
                                        result = result.clone().and(Err(APIError::APIMisuseError {
                                                err: "Batch funding transaction with the same txid already exists".to_owned()
                                        }));
                                        None
                                },
                                btree_map::Entry::Vacant(vacant) => Some(vacant.insert(Vec::new())),
                        }
                });
                for &(temporary_channel_id, counterparty_node_id) in temporary_channels {
                        result = result.and_then(|_| self.funding_transaction_generated_intern(
                                temporary_channel_id,
                                counterparty_node_id,
                                funding_transaction.clone(),
                                is_batch_funding,
                                |chan, tx| {
                                        let mut output_index = None;
                                        let expected_spk = chan.context.get_funding_redeemscript().to_v0_p2wsh();
                                        for (idx, outp) in tx.output.iter().enumerate() {
                                                if outp.script_pubkey == expected_spk && outp.value == chan.context.get_value_satoshis() {
                                                        if output_index.is_some() {
                                                                return Err(APIError::APIMisuseError {
                                                                        err: "Multiple outputs matched the expected script and value".to_owned()
                                                                });
                                                        }
                                                        output_index = Some(idx as u16);
                                                }
                                        }
                                        if output_index.is_none() {
                                                return Err(APIError::APIMisuseError {
                                                        err: "No output matched the script_pubkey and value in the FundingGenerationReady event".to_owned()
                                                });
                                        }
                                        let outpoint = OutPoint { txid: tx.txid(), index: output_index.unwrap() };
                                        if let Some(funding_batch_state) = funding_batch_state.as_mut() {
                                                funding_batch_state.push((outpoint.to_channel_id(), *counterparty_node_id, false));
                                        }
                                        Ok(outpoint)
                                })
                        );
                }
                if let Err(ref e) = result {
                        // Remaining channels need to be removed on any error.
                        let e = format!("Error in transaction funding: {:?}", e);
                        let mut channels_to_remove = Vec::new();
                        channels_to_remove.extend(funding_batch_states.as_mut()
                                .and_then(|states| states.remove(&txid))
                                .into_iter().flatten()
                                .map(|(chan_id, node_id, _state)| (chan_id, node_id))
                        );
                        channels_to_remove.extend(temporary_channels.iter()
                                .map(|(&chan_id, &node_id)| (chan_id, node_id))
                        );
                        let mut shutdown_results = Vec::new();
                        {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                for (channel_id, counterparty_node_id) in channels_to_remove {
                                        per_peer_state.get(&counterparty_node_id)
                                                .map(|peer_state_mutex| peer_state_mutex.lock().unwrap())
                                                .and_then(|mut peer_state| peer_state.channel_by_id.remove(&channel_id))
                                                .map(|mut chan| {
                                                        update_maps_on_chan_removal!(self, &chan.context());
                                                        self.issue_channel_close_events(&chan.context(), ClosureReason::ProcessingError { err: e.clone() });
                                                        shutdown_results.push(chan.context_mut().force_shutdown(false));
                                                });
                                }
                        }
                        for shutdown_result in shutdown_results.drain(..) {
                                self.finish_close_channel(shutdown_result);
                        }
                }
                result
        }

        /// Atomically applies partial updates to the [`ChannelConfig`] of the given channels.
        ///
        /// Once the updates are applied, each eligible channel (advertised with a known short channel
        /// ID and a change in [`forwarding_fee_proportional_millionths`], [`forwarding_fee_base_msat`],
        /// or [`cltv_expiry_delta`]) has a [`BroadcastChannelUpdate`] event message generated
        /// containing the new [`ChannelUpdate`] message which should be broadcast to the network.
        ///
        /// Returns [`ChannelUnavailable`] when a channel is not found or an incorrect
        /// `counterparty_node_id` is provided.
        ///
        /// Returns [`APIMisuseError`] when a [`cltv_expiry_delta`] update is to be applied with a value
        /// below [`MIN_CLTV_EXPIRY_DELTA`].
        ///
        /// If an error is returned, none of the updates should be considered applied.
        ///
        /// [`forwarding_fee_proportional_millionths`]: ChannelConfig::forwarding_fee_proportional_millionths
        /// [`forwarding_fee_base_msat`]: ChannelConfig::forwarding_fee_base_msat
        /// [`cltv_expiry_delta`]: ChannelConfig::cltv_expiry_delta
        /// [`BroadcastChannelUpdate`]: events::MessageSendEvent::BroadcastChannelUpdate
        /// [`ChannelUpdate`]: msgs::ChannelUpdate
        /// [`ChannelUnavailable`]: APIError::ChannelUnavailable
        /// [`APIMisuseError`]: APIError::APIMisuseError
        pub fn update_partial_channel_config(
                &self, counterparty_node_id: &PublicKey, channel_ids: &[ChannelId], config_update: &ChannelConfigUpdate,
        ) -> Result<(), APIError> {
                if config_update.cltv_expiry_delta.map(|delta| delta < MIN_CLTV_EXPIRY_DELTA).unwrap_or(false) {
                        return Err(APIError::APIMisuseError {
                                err: format!("The chosen CLTV expiry delta is below the minimum of {}", MIN_CLTV_EXPIRY_DELTA),
                        });
                }

                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                for channel_id in channel_ids {
                        if !peer_state.has_channel(channel_id) {
                                return Err(APIError::ChannelUnavailable {
                                        err: format!("Channel with id {} not found for the passed counterparty node_id {}", channel_id, counterparty_node_id),
                                });
                        };
                }
                for channel_id in channel_ids {
                        if let Some(channel_phase) = peer_state.channel_by_id.get_mut(channel_id) {
                                let mut config = channel_phase.context().config();
                                config.apply(config_update);
                                if !channel_phase.context_mut().update_config(&config) {
                                        continue;
                                }
                                if let ChannelPhase::Funded(channel) = channel_phase {
                                        if let Ok(msg) = self.get_channel_update_for_broadcast(channel) {
                                                peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate { msg });
                                        } else if let Ok(msg) = self.get_channel_update_for_unicast(channel) {
                                                peer_state.pending_msg_events.push(events::MessageSendEvent::SendChannelUpdate {
                                                        node_id: channel.context.get_counterparty_node_id(),
                                                        msg,
                                                });
                                        }
                                }
                                continue;
                        } else {
                                // This should not be reachable as we've already checked for non-existence in the previous channel_id loop.
                                debug_assert!(false);
                                return Err(APIError::ChannelUnavailable {
                                        err: format!(
                                                "Channel with ID {} for passed counterparty_node_id {} disappeared after we confirmed its existence - this should not be reachable!",
                                                channel_id, counterparty_node_id),
                                });
                        };
                }
                Ok(())
        }

        /// Atomically updates the [`ChannelConfig`] for the given channels.
        ///
        /// Once the updates are applied, each eligible channel (advertised with a known short channel
        /// ID and a change in [`forwarding_fee_proportional_millionths`], [`forwarding_fee_base_msat`],
        /// or [`cltv_expiry_delta`]) has a [`BroadcastChannelUpdate`] event message generated
        /// containing the new [`ChannelUpdate`] message which should be broadcast to the network.
        ///
        /// Returns [`ChannelUnavailable`] when a channel is not found or an incorrect
        /// `counterparty_node_id` is provided.
        ///
        /// Returns [`APIMisuseError`] when a [`cltv_expiry_delta`] update is to be applied with a value
        /// below [`MIN_CLTV_EXPIRY_DELTA`].
        ///
        /// If an error is returned, none of the updates should be considered applied.
        ///
        /// [`forwarding_fee_proportional_millionths`]: ChannelConfig::forwarding_fee_proportional_millionths
        /// [`forwarding_fee_base_msat`]: ChannelConfig::forwarding_fee_base_msat
        /// [`cltv_expiry_delta`]: ChannelConfig::cltv_expiry_delta
        /// [`BroadcastChannelUpdate`]: events::MessageSendEvent::BroadcastChannelUpdate
        /// [`ChannelUpdate`]: msgs::ChannelUpdate
        /// [`ChannelUnavailable`]: APIError::ChannelUnavailable
        /// [`APIMisuseError`]: APIError::APIMisuseError
        pub fn update_channel_config(
                &self, counterparty_node_id: &PublicKey, channel_ids: &[ChannelId], config: &ChannelConfig,
        ) -> Result<(), APIError> {
                return self.update_partial_channel_config(counterparty_node_id, channel_ids, &(*config).into());
        }

        /// Attempts to forward an intercepted HTLC over the provided channel id and with the provided
        /// amount to forward. Should only be called in response to an [`HTLCIntercepted`] event.
        ///
        /// Intercepted HTLCs can be useful for Lightning Service Providers (LSPs) to open a just-in-time
        /// channel to a receiving node if the node lacks sufficient inbound liquidity.
        ///
        /// To make use of intercepted HTLCs, set [`UserConfig::accept_intercept_htlcs`] and use
        /// [`ChannelManager::get_intercept_scid`] to generate short channel id(s) to put in the
        /// receiver's invoice route hints. These route hints will signal to LDK to generate an
        /// [`HTLCIntercepted`] event when it receives the forwarded HTLC, and this method or
        /// [`ChannelManager::fail_intercepted_htlc`] MUST be called in response to the event.
        ///
        /// Note that LDK does not enforce fee requirements in `amt_to_forward_msat`, and will not stop
        /// you from forwarding more than you received. See
        /// [`HTLCIntercepted::expected_outbound_amount_msat`] for more on forwarding a different amount
        /// than expected.
        ///
        /// Errors if the event was not handled in time, in which case the HTLC was automatically failed
        /// backwards.
        ///
        /// [`UserConfig::accept_intercept_htlcs`]: crate::util::config::UserConfig::accept_intercept_htlcs
        /// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
        /// [`HTLCIntercepted::expected_outbound_amount_msat`]: events::Event::HTLCIntercepted::expected_outbound_amount_msat
        // TODO: when we move to deciding the best outbound channel at forward time, only take
        // `next_node_id` and not `next_hop_channel_id`
        pub fn forward_intercepted_htlc(&self, intercept_id: InterceptId, next_hop_channel_id: &ChannelId, next_node_id: PublicKey, amt_to_forward_msat: u64) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let next_hop_scid = {
                        let peer_state_lock = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = peer_state_lock.get(&next_node_id)
                                .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", next_node_id) })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.get(next_hop_channel_id) {
                                Some(ChannelPhase::Funded(chan)) => {
                                        if !chan.context.is_usable() {
                                                return Err(APIError::ChannelUnavailable {
                                                        err: format!("Channel with id {} not fully established", next_hop_channel_id)
                                                })
                                        }
                                        chan.context.get_short_channel_id().unwrap_or(chan.context.outbound_scid_alias())
                                },
                                Some(_) => return Err(APIError::ChannelUnavailable {
                                        err: format!("Channel with id {} for the passed counterparty node_id {} is still opening.",
                                                next_hop_channel_id, next_node_id)
                                }),
                                None => {
                                        let error = format!("Channel with id {} not found for the passed counterparty node_id {}",
                                                next_hop_channel_id, next_node_id);
                                        log_error!(self.logger, "{} when attempting to forward intercepted HTLC", error);
                                        return Err(APIError::ChannelUnavailable {
                                                err: error
                                        })
                                }
                        }
                };

                let payment = self.pending_intercepted_htlcs.lock().unwrap().remove(&intercept_id)
                        .ok_or_else(|| APIError::APIMisuseError {
                                err: format!("Payment with intercept id {} not found", log_bytes!(intercept_id.0))
                        })?;

                let routing = match payment.forward_info.routing {
                        PendingHTLCRouting::Forward { onion_packet, .. } => {
                                PendingHTLCRouting::Forward { onion_packet, short_channel_id: next_hop_scid }
                        },
                        _ => unreachable!() // Only `PendingHTLCRouting::Forward`s are intercepted
                };
                let skimmed_fee_msat =
                        payment.forward_info.outgoing_amt_msat.saturating_sub(amt_to_forward_msat);
                let pending_htlc_info = PendingHTLCInfo {
                        skimmed_fee_msat: if skimmed_fee_msat == 0 { None } else { Some(skimmed_fee_msat) },
                        outgoing_amt_msat: amt_to_forward_msat, routing, ..payment.forward_info
                };

                let mut per_source_pending_forward = [(
                        payment.prev_short_channel_id,
                        payment.prev_funding_outpoint,
                        payment.prev_user_channel_id,
                        vec![(pending_htlc_info, payment.prev_htlc_id)]
                )];
                self.forward_htlcs(&mut per_source_pending_forward);
                Ok(())
        }

        /// Fails the intercepted HTLC indicated by intercept_id. Should only be called in response to
        /// an [`HTLCIntercepted`] event. See [`ChannelManager::forward_intercepted_htlc`].
        ///
        /// Errors if the event was not handled in time, in which case the HTLC was automatically failed
        /// backwards.
        ///
        /// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
        pub fn fail_intercepted_htlc(&self, intercept_id: InterceptId) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let payment = self.pending_intercepted_htlcs.lock().unwrap().remove(&intercept_id)
                        .ok_or_else(|| APIError::APIMisuseError {
                                err: format!("Payment with intercept id {} not found", log_bytes!(intercept_id.0))
                        })?;

                if let PendingHTLCRouting::Forward { short_channel_id, .. } = payment.forward_info.routing {
                        let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                short_channel_id: payment.prev_short_channel_id,
                                user_channel_id: Some(payment.prev_user_channel_id),
                                outpoint: payment.prev_funding_outpoint,
                                htlc_id: payment.prev_htlc_id,
                                incoming_packet_shared_secret: payment.forward_info.incoming_shared_secret,
                                phantom_shared_secret: None,
                        });

                        let failure_reason = HTLCFailReason::from_failure_code(0x4000 | 10);
                        let destination = HTLCDestination::UnknownNextHop { requested_forward_scid: short_channel_id };
                        self.fail_htlc_backwards_internal(&htlc_source, &payment.forward_info.payment_hash, &failure_reason, destination);
                } else { unreachable!() } // Only `PendingHTLCRouting::Forward`s are intercepted

                Ok(())
        }

        /// Processes HTLCs which are pending waiting on random forward delay.
        ///
        /// Should only really ever be called in response to a PendingHTLCsForwardable event.
        /// Will likely generate further events.
        pub fn process_pending_htlc_forwards(&self) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let mut new_events = VecDeque::new();
                let mut failed_forwards = Vec::new();
                let mut phantom_receives: Vec<(u64, OutPoint, u128, Vec<(PendingHTLCInfo, u64)>)> = Vec::new();
                {
                        let mut forward_htlcs = HashMap::new();
                        mem::swap(&mut forward_htlcs, &mut self.forward_htlcs.lock().unwrap());

                        for (short_chan_id, mut pending_forwards) in forward_htlcs {
                                if short_chan_id != 0 {
                                        macro_rules! forwarding_channel_not_found {
                                                () => {
                                                        for forward_info in pending_forwards.drain(..) {
                                                                match forward_info {
                                                                        HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                                prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id,
                                                                                forward_info: PendingHTLCInfo {
                                                                                        routing, incoming_shared_secret, payment_hash, outgoing_amt_msat,
                                                                                        outgoing_cltv_value, ..
                                                                                }
                                                                        }) => {
                                                                                macro_rules! failure_handler {
                                                                                        ($msg: expr, $err_code: expr, $err_data: expr, $phantom_ss: expr, $next_hop_unknown: expr) => {
                                                                                                log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);

                                                                                                let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                                                                                        short_channel_id: prev_short_channel_id,
                                                                                                        user_channel_id: Some(prev_user_channel_id),
                                                                                                        outpoint: prev_funding_outpoint,
                                                                                                        htlc_id: prev_htlc_id,
                                                                                                        incoming_packet_shared_secret: incoming_shared_secret,
                                                                                                        phantom_shared_secret: $phantom_ss,
                                                                                                });

                                                                                                let reason = if $next_hop_unknown {
                                                                                                        HTLCDestination::UnknownNextHop { requested_forward_scid: short_chan_id }
                                                                                                } else {
                                                                                                        HTLCDestination::FailedPayment{ payment_hash }
                                                                                                };

                                                                                                failed_forwards.push((htlc_source, payment_hash,
                                                                                                        HTLCFailReason::reason($err_code, $err_data),
                                                                                                        reason
                                                                                                ));
                                                                                                continue;
                                                                                        }
                                                                                }
                                                                                macro_rules! fail_forward {
                                                                                        ($msg: expr, $err_code: expr, $err_data: expr, $phantom_ss: expr) => {
                                                                                                {
                                                                                                        failure_handler!($msg, $err_code, $err_data, $phantom_ss, true);
                                                                                                }
                                                                                        }
                                                                                }
                                                                                macro_rules! failed_payment {
                                                                                        ($msg: expr, $err_code: expr, $err_data: expr, $phantom_ss: expr) => {
                                                                                                {
                                                                                                        failure_handler!($msg, $err_code, $err_data, $phantom_ss, false);
                                                                                                }
                                                                                        }
                                                                                }
                                                                                if let PendingHTLCRouting::Forward { onion_packet, .. } = routing {
                                                                                        let phantom_pubkey_res = self.node_signer.get_node_id(Recipient::PhantomNode);
                                                                                        if phantom_pubkey_res.is_ok() && fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, short_chan_id, &self.chain_hash) {
                                                                                                let phantom_shared_secret = self.node_signer.ecdh(Recipient::PhantomNode, &onion_packet.public_key.unwrap(), None).unwrap().secret_bytes();
                                                                                                let next_hop = match onion_utils::decode_next_payment_hop(
                                                                                                        phantom_shared_secret, &onion_packet.hop_data, onion_packet.hmac,
                                                                                                        payment_hash, &self.node_signer
                                                                                                ) {
                                                                                                        Ok(res) => res,
                                                                                                        Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
                                                                                                                let sha256_of_onion = Sha256::hash(&onion_packet.hop_data).to_byte_array();
                                                                                                                // In this scenario, the phantom would have sent us an
                                                                                                                // `update_fail_malformed_htlc`, meaning here we encrypt the error as
                                                                                                                // if it came from us (the second-to-last hop) but contains the sha256
                                                                                                                // of the onion.
                                                                                                                failed_payment!(err_msg, err_code, sha256_of_onion.to_vec(), None);
                                                                                                        },
                                                                                                        Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code }) => {
                                                                                                                failed_payment!(err_msg, err_code, Vec::new(), Some(phantom_shared_secret));
                                                                                                        },
                                                                                                };
                                                                                                match next_hop {
                                                                                                        onion_utils::Hop::Receive(hop_data) => {
                                                                                                                let current_height: u32 = self.best_block.read().unwrap().height();
                                                                                                                match create_recv_pending_htlc_info(hop_data,
                                                                                                                        incoming_shared_secret, payment_hash, outgoing_amt_msat,
                                                                                                                        outgoing_cltv_value, Some(phantom_shared_secret), false, None,
                                                                                                                        current_height, self.default_configuration.accept_mpp_keysend)
                                                                                                                {
                                                                                                                        Ok(info) => phantom_receives.push((prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, vec![(info, prev_htlc_id)])),
                                                                                                                        Err(InboundOnionErr { err_code, err_data, msg }) => failed_payment!(msg, err_code, err_data, Some(phantom_shared_secret))
                                                                                                                }
                                                                                                        },
                                                                                                        _ => panic!(),
                                                                                                }
                                                                                        } else {
                                                                                                fail_forward!(format!("Unknown short channel id {} for forward HTLC", short_chan_id), 0x4000 | 10, Vec::new(), None);
                                                                                        }
                                                                                } else {
                                                                                        fail_forward!(format!("Unknown short channel id {} for forward HTLC", short_chan_id), 0x4000 | 10, Vec::new(), None);
                                                                                }
                                                                        },
                                                                        HTLCForwardInfo::FailHTLC { .. } => {
                                                                                // Channel went away before we could fail it. This implies
                                                                                // the channel is now on chain and our counterparty is
                                                                                // trying to broadcast the HTLC-Timeout, but that's their
                                                                                // problem, not ours.
                                                                        }
                                                                }
                                                        }
                                                }
                                        }
                                        let chan_info_opt = self.short_to_chan_info.read().unwrap().get(&short_chan_id).cloned();
                                        let (counterparty_node_id, forward_chan_id) = match chan_info_opt {
                                                Some((cp_id, chan_id)) => (cp_id, chan_id),
                                                None => {
                                                        forwarding_channel_not_found!();
                                                        continue;
                                                }
                                        };
                                        let per_peer_state = self.per_peer_state.read().unwrap();
                                        let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
                                        if peer_state_mutex_opt.is_none() {
                                                forwarding_channel_not_found!();
                                                continue;
                                        }
                                        let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                                        let peer_state = &mut *peer_state_lock;
                                        if let Some(ChannelPhase::Funded(ref mut chan)) = peer_state.channel_by_id.get_mut(&forward_chan_id) {
                                                for forward_info in pending_forwards.drain(..) {
                                                        match forward_info {
                                                                HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                        prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id,
                                                                        forward_info: PendingHTLCInfo {
                                                                                incoming_shared_secret, payment_hash, outgoing_amt_msat, outgoing_cltv_value,
                                                                                routing: PendingHTLCRouting::Forward { onion_packet, .. }, skimmed_fee_msat, ..
                                                                        },
                                                                }) => {
                                                                        log_trace!(self.logger, "Adding HTLC from short id {} with payment_hash {} to channel with short id {} after delay", prev_short_channel_id, &payment_hash, short_chan_id);
                                                                        let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                                                                short_channel_id: prev_short_channel_id,
                                                                                user_channel_id: Some(prev_user_channel_id),
                                                                                outpoint: prev_funding_outpoint,
                                                                                htlc_id: prev_htlc_id,
                                                                                incoming_packet_shared_secret: incoming_shared_secret,
                                                                                // Phantom payments are only PendingHTLCRouting::Receive.
                                                                                phantom_shared_secret: None,
                                                                        });
                                                                        if let Err(e) = chan.queue_add_htlc(outgoing_amt_msat,
                                                                                payment_hash, outgoing_cltv_value, htlc_source.clone(),
                                                                                onion_packet, skimmed_fee_msat, &self.fee_estimator,
                                                                                &self.logger)
                                                                        {
                                                                                if let ChannelError::Ignore(msg) = e {
                                                                                        log_trace!(self.logger, "Failed to forward HTLC with payment_hash {}: {}", &payment_hash, msg);
                                                                                } else {
                                                                                        panic!("Stated return value requirements in send_htlc() were not met");
                                                                                }
                                                                                let (failure_code, data) = self.get_htlc_temp_fail_err_and_data(0x1000|7, short_chan_id, chan);
                                                                                failed_forwards.push((htlc_source, payment_hash,
                                                                                        HTLCFailReason::reason(failure_code, data),
                                                                                        HTLCDestination::NextHopChannel { node_id: Some(chan.context.get_counterparty_node_id()), channel_id: forward_chan_id }
                                                                                ));
                                                                                continue;
                                                                        }
                                                                },
                                                                HTLCForwardInfo::AddHTLC { .. } => {
                                                                        panic!("short_channel_id != 0 should imply any pending_forward entries are of type Forward");
                                                                },
                                                                HTLCForwardInfo::FailHTLC { htlc_id, err_packet } => {
                                                                        log_trace!(self.logger, "Failing HTLC back to channel with short id {} (backward HTLC ID {}) after delay", short_chan_id, htlc_id);
                                                                        if let Err(e) = chan.queue_fail_htlc(
                                                                                htlc_id, err_packet, &self.logger
                                                                        ) {
                                                                                if let ChannelError::Ignore(msg) = e {
                                                                                        log_trace!(self.logger, "Failed to fail HTLC with ID {} backwards to short_id {}: {}", htlc_id, short_chan_id, msg);
                                                                                } else {
                                                                                        panic!("Stated return value requirements in queue_fail_htlc() were not met");
                                                                                }
                                                                                // fail-backs are best-effort, we probably already have one
                                                                                // pending, and if not that's OK, if not, the channel is on
                                                                                // the chain and sending the HTLC-Timeout is their problem.
                                                                                continue;
                                                                        }
                                                                },
                                                        }
                                                }
                                        } else {
                                                forwarding_channel_not_found!();
                                                continue;
                                        }
                                } else {
                                        'next_forwardable_htlc: for forward_info in pending_forwards.drain(..) {
                                                match forward_info {
                                                        HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id,
                                                                forward_info: PendingHTLCInfo {
                                                                        routing, incoming_shared_secret, payment_hash, incoming_amt_msat, outgoing_amt_msat,
                                                                        skimmed_fee_msat, ..
                                                                }
                                                        }) => {
                                                                let (cltv_expiry, onion_payload, payment_data, phantom_shared_secret, mut onion_fields) = match routing {
                                                                        PendingHTLCRouting::Receive { payment_data, payment_metadata, incoming_cltv_expiry, phantom_shared_secret, custom_tlvs } => {
                                                                                let _legacy_hop_data = Some(payment_data.clone());
                                                                                let onion_fields = RecipientOnionFields { payment_secret: Some(payment_data.payment_secret),
                                                                                                payment_metadata, custom_tlvs };
                                                                                (incoming_cltv_expiry, OnionPayload::Invoice { _legacy_hop_data },
                                                                                        Some(payment_data), phantom_shared_secret, onion_fields)
                                                                        },
                                                                        PendingHTLCRouting::ReceiveKeysend { payment_data, payment_preimage, payment_metadata, incoming_cltv_expiry, custom_tlvs } => {
                                                                                let onion_fields = RecipientOnionFields {
                                                                                        payment_secret: payment_data.as_ref().map(|data| data.payment_secret),
                                                                                        payment_metadata,
                                                                                        custom_tlvs,
                                                                                };
                                                                                (incoming_cltv_expiry, OnionPayload::Spontaneous(payment_preimage),
                                                                                        payment_data, None, onion_fields)
                                                                        },
                                                                        _ => {
                                                                                panic!("short_channel_id == 0 should imply any pending_forward entries are of type Receive");
                                                                        }
                                                                };
                                                                let claimable_htlc = ClaimableHTLC {
                                                                        prev_hop: HTLCPreviousHopData {
                                                                                short_channel_id: prev_short_channel_id,
                                                                                user_channel_id: Some(prev_user_channel_id),
                                                                                outpoint: prev_funding_outpoint,
                                                                                htlc_id: prev_htlc_id,
                                                                                incoming_packet_shared_secret: incoming_shared_secret,
                                                                                phantom_shared_secret,
                                                                        },
                                                                        // We differentiate the received value from the sender intended value
                                                                        // if possible so that we don't prematurely mark MPP payments complete
                                                                        // if routing nodes overpay
                                                                        value: incoming_amt_msat.unwrap_or(outgoing_amt_msat),
                                                                        sender_intended_value: outgoing_amt_msat,
                                                                        timer_ticks: 0,
                                                                        total_value_received: None,
                                                                        total_msat: if let Some(data) = &payment_data { data.total_msat } else { outgoing_amt_msat },
                                                                        cltv_expiry,
                                                                        onion_payload,
                                                                        counterparty_skimmed_fee_msat: skimmed_fee_msat,
                                                                };

                                                                let mut committed_to_claimable = false;

                                                                macro_rules! fail_htlc {
                                                                        ($htlc: expr, $payment_hash: expr) => {
                                                                                debug_assert!(!committed_to_claimable);
                                                                                let mut htlc_msat_height_data = $htlc.value.to_be_bytes().to_vec();
                                                                                htlc_msat_height_data.extend_from_slice(
                                                                                        &self.best_block.read().unwrap().height().to_be_bytes(),
                                                                                );
                                                                                failed_forwards.push((HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                                                                                short_channel_id: $htlc.prev_hop.short_channel_id,
                                                                                                user_channel_id: $htlc.prev_hop.user_channel_id,
                                                                                                outpoint: prev_funding_outpoint,
                                                                                                htlc_id: $htlc.prev_hop.htlc_id,
                                                                                                incoming_packet_shared_secret: $htlc.prev_hop.incoming_packet_shared_secret,
                                                                                                phantom_shared_secret,
                                                                                        }), payment_hash,
                                                                                        HTLCFailReason::reason(0x4000 | 15, htlc_msat_height_data),
                                                                                        HTLCDestination::FailedPayment { payment_hash: $payment_hash },
                                                                                ));
                                                                                continue 'next_forwardable_htlc;
                                                                        }
                                                                }
                                                                let phantom_shared_secret = claimable_htlc.prev_hop.phantom_shared_secret;
                                                                let mut receiver_node_id = self.our_network_pubkey;
                                                                if phantom_shared_secret.is_some() {
                                                                        receiver_node_id = self.node_signer.get_node_id(Recipient::PhantomNode)
                                                                                .expect("Failed to get node_id for phantom node recipient");
                                                                }

                                                                macro_rules! check_total_value {
                                                                        ($purpose: expr) => {{
                                                                                let mut payment_claimable_generated = false;
                                                                                let is_keysend = match $purpose {
                                                                                        events::PaymentPurpose::SpontaneousPayment(_) => true,
                                                                                        events::PaymentPurpose::InvoicePayment { .. } => false,
                                                                                };
                                                                                let mut claimable_payments = self.claimable_payments.lock().unwrap();
                                                                                if claimable_payments.pending_claiming_payments.contains_key(&payment_hash) {
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                }
                                                                                let ref mut claimable_payment = claimable_payments.claimable_payments
                                                                                        .entry(payment_hash)
                                                                                        // Note that if we insert here we MUST NOT fail_htlc!()
                                                                                        .or_insert_with(|| {
                                                                                                committed_to_claimable = true;
                                                                                                ClaimablePayment {
                                                                                                        purpose: $purpose.clone(), htlcs: Vec::new(), onion_fields: None,
                                                                                                }
                                                                                        });
                                                                                if $purpose != claimable_payment.purpose {
                                                                                        let log_keysend = |keysend| if keysend { "keysend" } else { "non-keysend" };
                                                                                        log_trace!(self.logger, "Failing new {} HTLC with payment_hash {} as we already had an existing {} HTLC with the same payment hash", log_keysend(is_keysend), &payment_hash, log_keysend(!is_keysend));
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                }
                                                                                if !self.default_configuration.accept_mpp_keysend && is_keysend && !claimable_payment.htlcs.is_empty() {
                                                                                        log_trace!(self.logger, "Failing new keysend HTLC with payment_hash {} as we already had an existing keysend HTLC with the same payment hash and our config states we don't accept MPP keysend", &payment_hash);
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                }
                                                                                if let Some(earlier_fields) = &mut claimable_payment.onion_fields {
                                                                                        if earlier_fields.check_merge(&mut onion_fields).is_err() {
                                                                                                fail_htlc!(claimable_htlc, payment_hash);
                                                                                        }
                                                                                } else {
                                                                                        claimable_payment.onion_fields = Some(onion_fields);
                                                                                }
                                                                                let ref mut htlcs = &mut claimable_payment.htlcs;
                                                                                let mut total_value = claimable_htlc.sender_intended_value;
                                                                                let mut earliest_expiry = claimable_htlc.cltv_expiry;
                                                                                for htlc in htlcs.iter() {
                                                                                        total_value += htlc.sender_intended_value;
                                                                                        earliest_expiry = cmp::min(earliest_expiry, htlc.cltv_expiry);
                                                                                        if htlc.total_msat != claimable_htlc.total_msat {
                                                                                                log_trace!(self.logger, "Failing HTLCs with payment_hash {} as the HTLCs had inconsistent total values (eg {} and {})",
                                                                                                        &payment_hash, claimable_htlc.total_msat, htlc.total_msat);
                                                                                                total_value = msgs::MAX_VALUE_MSAT;
                                                                                        }
                                                                                        if total_value >= msgs::MAX_VALUE_MSAT { break; }
                                                                                }
                                                                                // The condition determining whether an MPP is complete must
                                                                                // match exactly the condition used in `timer_tick_occurred`
                                                                                if total_value >= msgs::MAX_VALUE_MSAT {
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                } else if total_value - claimable_htlc.sender_intended_value >= claimable_htlc.total_msat {
                                                                                        log_trace!(self.logger, "Failing HTLC with payment_hash {} as payment is already claimable",
                                                                                                &payment_hash);
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                } else if total_value >= claimable_htlc.total_msat {
                                                                                        #[allow(unused_assignments)] {
                                                                                                committed_to_claimable = true;
                                                                                        }
                                                                                        let prev_channel_id = prev_funding_outpoint.to_channel_id();
                                                                                        htlcs.push(claimable_htlc);
                                                                                        let amount_msat = htlcs.iter().map(|htlc| htlc.value).sum();
                                                                                        htlcs.iter_mut().for_each(|htlc| htlc.total_value_received = Some(amount_msat));
                                                                                        let counterparty_skimmed_fee_msat = htlcs.iter()
                                                                                                .map(|htlc| htlc.counterparty_skimmed_fee_msat.unwrap_or(0)).sum();
                                                                                        debug_assert!(total_value.saturating_sub(amount_msat) <=
                                                                                                counterparty_skimmed_fee_msat);
                                                                                        new_events.push_back((events::Event::PaymentClaimable {
                                                                                                receiver_node_id: Some(receiver_node_id),
                                                                                                payment_hash,
                                                                                                purpose: $purpose,
                                                                                                amount_msat,
                                                                                                counterparty_skimmed_fee_msat,
                                                                                                via_channel_id: Some(prev_channel_id),
                                                                                                via_user_channel_id: Some(prev_user_channel_id),
                                                                                                claim_deadline: Some(earliest_expiry - HTLC_FAIL_BACK_BUFFER),
                                                                                                onion_fields: claimable_payment.onion_fields.clone(),
                                                                                        }, None));
                                                                                        payment_claimable_generated = true;
                                                                                } else {
                                                                                        // Nothing to do - we haven't reached the total
                                                                                        // payment value yet, wait until we receive more
                                                                                        // MPP parts.
                                                                                        htlcs.push(claimable_htlc);
                                                                                        #[allow(unused_assignments)] {
                                                                                                committed_to_claimable = true;
                                                                                        }
                                                                                }
                                                                                payment_claimable_generated
                                                                        }}
                                                                }

                                                                // Check that the payment hash and secret are known. Note that we
                                                                // MUST take care to handle the "unknown payment hash" and
                                                                // "incorrect payment secret" cases here identically or we'd expose
                                                                // that we are the ultimate recipient of the given payment hash.
                                                                // Further, we must not expose whether we have any other HTLCs
                                                                // associated with the same payment_hash pending or not.
                                                                let mut payment_secrets = self.pending_inbound_payments.lock().unwrap();
                                                                match payment_secrets.entry(payment_hash) {
                                                                        hash_map::Entry::Vacant(_) => {
                                                                                match claimable_htlc.onion_payload {
                                                                                        OnionPayload::Invoice { .. } => {
                                                                                                let payment_data = payment_data.unwrap();
                                                                                                let (payment_preimage, min_final_cltv_expiry_delta) = match inbound_payment::verify(payment_hash, &payment_data, self.highest_seen_timestamp.load(Ordering::Acquire) as u64, &self.inbound_payment_key, &self.logger) {
                                                                                                        Ok(result) => result,
                                                                                                        Err(()) => {
                                                                                                                log_trace!(self.logger, "Failing new HTLC with payment_hash {} as payment verification failed", &payment_hash);
                                                                                                                fail_htlc!(claimable_htlc, payment_hash);
                                                                                                        }
                                                                                                };
                                                                                                if let Some(min_final_cltv_expiry_delta) = min_final_cltv_expiry_delta {
                                                                                                        let expected_min_expiry_height = (self.current_best_block().height() + min_final_cltv_expiry_delta as u32) as u64;
                                                                                                        if (cltv_expiry as u64) < expected_min_expiry_height {
                                                                                                                log_trace!(self.logger, "Failing new HTLC with payment_hash {} as its CLTV expiry was too soon (had {}, earliest expected {})",
                                                                                                                        &payment_hash, cltv_expiry, expected_min_expiry_height);
                                                                                                                fail_htlc!(claimable_htlc, payment_hash);
                                                                                                        }
                                                                                                }
                                                                                                let purpose = events::PaymentPurpose::InvoicePayment {
                                                                                                        payment_preimage: payment_preimage.clone(),
                                                                                                        payment_secret: payment_data.payment_secret,
                                                                                                };
                                                                                                check_total_value!(purpose);
                                                                                        },
                                                                                        OnionPayload::Spontaneous(preimage) => {
                                                                                                let purpose = events::PaymentPurpose::SpontaneousPayment(preimage);
                                                                                                check_total_value!(purpose);
                                                                                        }
                                                                                }
                                                                        },
                                                                        hash_map::Entry::Occupied(inbound_payment) => {
                                                                                if let OnionPayload::Spontaneous(_) = claimable_htlc.onion_payload {
                                                                                        log_trace!(self.logger, "Failing new keysend HTLC with payment_hash {} because we already have an inbound payment with the same payment hash", &payment_hash);
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                }
                                                                                let payment_data = payment_data.unwrap();
                                                                                if inbound_payment.get().payment_secret != payment_data.payment_secret {
                                                                                        log_trace!(self.logger, "Failing new HTLC with payment_hash {} as it didn't match our expected payment secret.", &payment_hash);
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                } else if inbound_payment.get().min_value_msat.is_some() && payment_data.total_msat < inbound_payment.get().min_value_msat.unwrap() {
                                                                                        log_trace!(self.logger, "Failing new HTLC with payment_hash {} as it didn't match our minimum value (had {}, needed {}).",
                                                                                                &payment_hash, payment_data.total_msat, inbound_payment.get().min_value_msat.unwrap());
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                } else {
                                                                                        let purpose = events::PaymentPurpose::InvoicePayment {
                                                                                                payment_preimage: inbound_payment.get().payment_preimage,
                                                                                                payment_secret: payment_data.payment_secret,
                                                                                        };
                                                                                        let payment_claimable_generated = check_total_value!(purpose);
                                                                                        if payment_claimable_generated {
                                                                                                inbound_payment.remove_entry();
                                                                                        }
                                                                                }
                                                                        },
                                                                };
                                                        },
                                                        HTLCForwardInfo::FailHTLC { .. } => {
                                                                panic!("Got pending fail of our own HTLC");
                                                        }
                                                }
                                        }
                                }
                        }
                }

                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments.check_retry_payments(&self.router, || self.list_usable_channels(),
                        || self.compute_inflight_htlcs(), &self.entropy_source, &self.node_signer, best_block_height,
                        &self.pending_events, &self.logger, |args| self.send_payment_along_path(args));

                for (htlc_source, payment_hash, failure_reason, destination) in failed_forwards.drain(..) {
                        self.fail_htlc_backwards_internal(&htlc_source, &payment_hash, &failure_reason, destination);
                }
                self.forward_htlcs(&mut phantom_receives);

                // Freeing the holding cell here is relatively redundant - in practice we'll do it when we
                // next get a `get_and_clear_pending_msg_events` call, but some tests rely on it, and it's
                // nice to do the work now if we can rather than while we're trying to get messages in the
                // network stack.
                self.check_free_holding_cells();

                if new_events.is_empty() { return }
                let mut events = self.pending_events.lock().unwrap();
                events.append(&mut new_events);
        }

        /// Free the background events, generally called from [`PersistenceNotifierGuard`] constructors.
        ///
        /// Expects the caller to have a total_consistency_lock read lock.
        fn process_background_events(&self) -> NotifyOption {
                debug_assert_ne!(self.total_consistency_lock.held_by_thread(), LockHeldState::NotHeldByThread);

                self.background_events_processed_since_startup.store(true, Ordering::Release);

                let mut background_events = Vec::new();
                mem::swap(&mut *self.pending_background_events.lock().unwrap(), &mut background_events);
                if background_events.is_empty() {
                        return NotifyOption::SkipPersistNoEvents;
                }

                for event in background_events.drain(..) {
                        match event {
                                BackgroundEvent::ClosedMonitorUpdateRegeneratedOnStartup((funding_txo, update)) => {
                                        // The channel has already been closed, so no use bothering to care about the
                                        // monitor updating completing.
                                        let _ = self.chain_monitor.update_channel(funding_txo, &update);
                                },
                                BackgroundEvent::MonitorUpdateRegeneratedOnStartup { counterparty_node_id, funding_txo, update } => {
                                        let mut updated_chan = false;
                                        {
                                                let per_peer_state = self.per_peer_state.read().unwrap();
                                                if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
                                                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                                        let peer_state = &mut *peer_state_lock;
                                                        match peer_state.channel_by_id.entry(funding_txo.to_channel_id()) {
                                                                hash_map::Entry::Occupied(mut chan_phase) => {
                                                                        if let ChannelPhase::Funded(chan) = chan_phase.get_mut() {
                                                                                updated_chan = true;
                                                                                handle_new_monitor_update!(self, funding_txo, update.clone(),
                                                                                        peer_state_lock, peer_state, per_peer_state, chan);
                                                                        } else {
                                                                                debug_assert!(false, "We shouldn't have an update for a non-funded channel");
                                                                        }
                                                                },
                                                                hash_map::Entry::Vacant(_) => {},
                                                        }
                                                }
                                        }
                                        if !updated_chan {
                                                // TODO: Track this as in-flight even though the channel is closed.
                                                let _ = self.chain_monitor.update_channel(funding_txo, &update);
                                        }
                                },
                                BackgroundEvent::MonitorUpdatesComplete { counterparty_node_id, channel_id } => {
                                        let per_peer_state = self.per_peer_state.read().unwrap();
                                        if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
                                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                                let peer_state = &mut *peer_state_lock;
                                                if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get_mut(&channel_id) {
                                                        handle_monitor_update_completion!(self, peer_state_lock, peer_state, per_peer_state, chan);
                                                } else {
                                                        let update_actions = peer_state.monitor_update_blocked_actions
                                                                .remove(&channel_id).unwrap_or(Vec::new());
                                                        mem::drop(peer_state_lock);
                                                        mem::drop(per_peer_state);
                                                        self.handle_monitor_update_completion_actions(update_actions);
                                                }
                                        }
                                },
                        }
                }
                NotifyOption::DoPersist
        }

        #[cfg(any(test, feature = "_test_utils"))]
        /// Process background events, for functional testing
        pub fn test_process_background_events(&self) {
                let _lck = self.total_consistency_lock.read().unwrap();
                let _ = self.process_background_events();
        }

        fn update_channel_fee(&self, chan_id: &ChannelId, chan: &mut Channel<SP>, new_feerate: u32) -> NotifyOption {
                if !chan.context.is_outbound() { return NotifyOption::SkipPersistNoEvents; }
                // If the feerate has decreased by less than half, don't bother
                if new_feerate <= chan.context.get_feerate_sat_per_1000_weight() && new_feerate * 2 > chan.context.get_feerate_sat_per_1000_weight() {
                        if new_feerate != chan.context.get_feerate_sat_per_1000_weight() {
                                log_trace!(self.logger, "Channel {} does not qualify for a feerate change from {} to {}.",
                                chan_id, chan.context.get_feerate_sat_per_1000_weight(), new_feerate);
                        }
                        return NotifyOption::SkipPersistNoEvents;
                }
                if !chan.context.is_live() {
                        log_trace!(self.logger, "Channel {} does not qualify for a feerate change from {} to {} as it cannot currently be updated (probably the peer is disconnected).",
                                chan_id, chan.context.get_feerate_sat_per_1000_weight(), new_feerate);
                        return NotifyOption::SkipPersistNoEvents;
                }
                log_trace!(self.logger, "Channel {} qualifies for a feerate change from {} to {}.",
                        &chan_id, chan.context.get_feerate_sat_per_1000_weight(), new_feerate);

                chan.queue_update_fee(new_feerate, &self.fee_estimator, &self.logger);
                NotifyOption::DoPersist
        }

        #[cfg(fuzzing)]
        /// In chanmon_consistency we want to sometimes do the channel fee updates done in
        /// timer_tick_occurred, but we can't generate the disabled channel updates as it considers
        /// these a fuzz failure (as they usually indicate a channel force-close, which is exactly what
        /// it wants to detect). Thus, we have a variant exposed here for its benefit.
        pub fn maybe_update_chan_fees(&self) {
                PersistenceNotifierGuard::optionally_notify(self, || {
                        let mut should_persist = NotifyOption::SkipPersistNoEvents;

                        let non_anchor_feerate = self.fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::NonAnchorChannelFee);
                        let anchor_feerate = self.fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::AnchorChannelFee);

                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                for (chan_id, chan) in peer_state.channel_by_id.iter_mut().filter_map(
                                        |(chan_id, phase)| if let ChannelPhase::Funded(chan) = phase { Some((chan_id, chan)) } else { None }
                                ) {
                                        let new_feerate = if chan.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
                                                anchor_feerate
                                        } else {
                                                non_anchor_feerate
                                        };
                                        let chan_needs_persist = self.update_channel_fee(chan_id, chan, new_feerate);
                                        if chan_needs_persist == NotifyOption::DoPersist { should_persist = NotifyOption::DoPersist; }
                                }
                        }

                        should_persist
                });
        }

        /// Performs actions which should happen on startup and roughly once per minute thereafter.
        ///
        /// This currently includes:
        ///  * Increasing or decreasing the on-chain feerate estimates for our outbound channels,
        ///  * Broadcasting [`ChannelUpdate`] messages if we've been disconnected from our peer for more
        ///    than a minute, informing the network that they should no longer attempt to route over
        ///    the channel.
        ///  * Expiring a channel's previous [`ChannelConfig`] if necessary to only allow forwarding HTLCs
        ///    with the current [`ChannelConfig`].
        ///  * Removing peers which have disconnected but and no longer have any channels.
        ///  * Force-closing and removing channels which have not completed establishment in a timely manner.
        ///  * Forgetting about stale outbound payments, either those that have already been fulfilled
        ///    or those awaiting an invoice that hasn't been delivered in the necessary amount of time.
        ///    The latter is determined using the system clock in `std` and the highest seen block time
        ///    minus two hours in `no-std`.
        ///
        /// Note that this may cause reentrancy through [`chain::Watch::update_channel`] calls or feerate
        /// estimate fetches.
        ///
        /// [`ChannelUpdate`]: msgs::ChannelUpdate
        /// [`ChannelConfig`]: crate::util::config::ChannelConfig
        pub fn timer_tick_occurred(&self) {
                PersistenceNotifierGuard::optionally_notify(self, || {
                        let mut should_persist = NotifyOption::SkipPersistNoEvents;

                        let non_anchor_feerate = self.fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::NonAnchorChannelFee);
                        let anchor_feerate = self.fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::AnchorChannelFee);

                        let mut handle_errors: Vec<(Result<(), _>, _)> = Vec::new();
                        let mut timed_out_mpp_htlcs = Vec::new();
                        let mut pending_peers_awaiting_removal = Vec::new();
                        let mut shutdown_channels = Vec::new();

                        let mut process_unfunded_channel_tick = |
                                chan_id: &ChannelId,
                                context: &mut ChannelContext<SP>,
                                unfunded_context: &mut UnfundedChannelContext,
                                pending_msg_events: &mut Vec<MessageSendEvent>,
                                counterparty_node_id: PublicKey,
                        | {
                                context.maybe_expire_prev_config();
                                if unfunded_context.should_expire_unfunded_channel() {
                                        log_error!(self.logger,
                                                "Force-closing pending channel with ID {} for not establishing in a timely manner", chan_id);
                                        update_maps_on_chan_removal!(self, &context);
                                        self.issue_channel_close_events(&context, ClosureReason::HolderForceClosed);
                                        shutdown_channels.push(context.force_shutdown(false));
                                        pending_msg_events.push(MessageSendEvent::HandleError {
                                                node_id: counterparty_node_id,
                                                action: msgs::ErrorAction::SendErrorMessage {
                                                        msg: msgs::ErrorMessage {
                                                                channel_id: *chan_id,
                                                                data: "Force-closing pending channel due to timeout awaiting establishment handshake".to_owned(),
                                                        },
                                                },
                                        });
                                        false
                                } else {
                                        true
                                }
                        };

                        {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                for (counterparty_node_id, peer_state_mutex) in per_peer_state.iter() {
                                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                        let peer_state = &mut *peer_state_lock;
                                        let pending_msg_events = &mut peer_state.pending_msg_events;
                                        let counterparty_node_id = *counterparty_node_id;
                                        peer_state.channel_by_id.retain(|chan_id, phase| {
                                                match phase {
                                                        ChannelPhase::Funded(chan) => {
                                                                let new_feerate = if chan.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
                                                                        anchor_feerate
                                                                } else {
                                                                        non_anchor_feerate
                                                                };
                                                                let chan_needs_persist = self.update_channel_fee(chan_id, chan, new_feerate);
                                                                if chan_needs_persist == NotifyOption::DoPersist { should_persist = NotifyOption::DoPersist; }

                                                                if let Err(e) = chan.timer_check_closing_negotiation_progress() {
                                                                        let (needs_close, err) = convert_chan_phase_err!(self, e, chan, chan_id, FUNDED_CHANNEL);
                                                                        handle_errors.push((Err(err), counterparty_node_id));
                                                                        if needs_close { return false; }
                                                                }

                                                                match chan.channel_update_status() {
                                                                        ChannelUpdateStatus::Enabled if !chan.context.is_live() => chan.set_channel_update_status(ChannelUpdateStatus::DisabledStaged(0)),
                                                                        ChannelUpdateStatus::Disabled if chan.context.is_live() => chan.set_channel_update_status(ChannelUpdateStatus::EnabledStaged(0)),
                                                                        ChannelUpdateStatus::DisabledStaged(_) if chan.context.is_live()
                                                                                => chan.set_channel_update_status(ChannelUpdateStatus::Enabled),
                                                                        ChannelUpdateStatus::EnabledStaged(_) if !chan.context.is_live()
                                                                                => chan.set_channel_update_status(ChannelUpdateStatus::Disabled),
                                                                        ChannelUpdateStatus::DisabledStaged(mut n) if !chan.context.is_live() => {
                                                                                n += 1;
                                                                                if n >= DISABLE_GOSSIP_TICKS {
                                                                                        chan.set_channel_update_status(ChannelUpdateStatus::Disabled);
                                                                                        if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                                                                                pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                                        msg: update
                                                                                                });
                                                                                        }
                                                                                        should_persist = NotifyOption::DoPersist;
                                                                                } else {
                                                                                        chan.set_channel_update_status(ChannelUpdateStatus::DisabledStaged(n));
                                                                                }
                                                                        },
                                                                        ChannelUpdateStatus::EnabledStaged(mut n) if chan.context.is_live() => {
                                                                                n += 1;
                                                                                if n >= ENABLE_GOSSIP_TICKS {
                                                                                        chan.set_channel_update_status(ChannelUpdateStatus::Enabled);
                                                                                        if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                                                                                pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                                        msg: update
                                                                                                });
                                                                                        }
                                                                                        should_persist = NotifyOption::DoPersist;
                                                                                } else {
                                                                                        chan.set_channel_update_status(ChannelUpdateStatus::EnabledStaged(n));
                                                                                }
                                                                        },
                                                                        _ => {},
                                                                }

                                                                chan.context.maybe_expire_prev_config();

                                                                if chan.should_disconnect_peer_awaiting_response() {
                                                                        log_debug!(self.logger, "Disconnecting peer {} due to not making any progress on channel {}",
                                                                                        counterparty_node_id, chan_id);
                                                                        pending_msg_events.push(MessageSendEvent::HandleError {
                                                                                node_id: counterparty_node_id,
                                                                                action: msgs::ErrorAction::DisconnectPeerWithWarning {
                                                                                        msg: msgs::WarningMessage {
                                                                                                channel_id: *chan_id,
                                                                                                data: "Disconnecting due to timeout awaiting response".to_owned(),
                                                                                        },
                                                                                },
                                                                        });
                                                                }

                                                                true
                                                        },
                                                        ChannelPhase::UnfundedInboundV1(chan) => {
                                                                process_unfunded_channel_tick(chan_id, &mut chan.context, &mut chan.unfunded_context,
                                                                        pending_msg_events, counterparty_node_id)
                                                        },
                                                        ChannelPhase::UnfundedOutboundV1(chan) => {
                                                                process_unfunded_channel_tick(chan_id, &mut chan.context, &mut chan.unfunded_context,
                                                                        pending_msg_events, counterparty_node_id)
                                                        },
                                                }
                                        });

                                        for (chan_id, req) in peer_state.inbound_channel_request_by_id.iter_mut() {
                                                if { req.ticks_remaining -= 1 ; req.ticks_remaining } <= 0 {
                                                        log_error!(self.logger, "Force-closing unaccepted inbound channel {} for not accepting in a timely manner", &chan_id);
                                                        peer_state.pending_msg_events.push(
                                                                events::MessageSendEvent::HandleError {
                                                                        node_id: counterparty_node_id,
                                                                        action: msgs::ErrorAction::SendErrorMessage {
                                                                                msg: msgs::ErrorMessage { channel_id: chan_id.clone(), data: "Channel force-closed".to_owned() }
                                                                        },
                                                                }
                                                        );
                                                }
                                        }
                                        peer_state.inbound_channel_request_by_id.retain(|_, req| req.ticks_remaining > 0);

                                        if peer_state.ok_to_remove(true) {
                                                pending_peers_awaiting_removal.push(counterparty_node_id);
                                        }
                                }
                        }

                        // When a peer disconnects but still has channels, the peer's `peer_state` entry in the
                        // `per_peer_state` is not removed by the `peer_disconnected` function. If the channels
                        // of to that peer is later closed while still being disconnected (i.e. force closed),
                        // we therefore need to remove the peer from `peer_state` separately.
                        // To avoid having to take the `per_peer_state` `write` lock once the channels are
                        // closed, we instead remove such peers awaiting removal here on a timer, to limit the
                        // negative effects on parallelism as much as possible.
                        if pending_peers_awaiting_removal.len() > 0 {
                                let mut per_peer_state = self.per_peer_state.write().unwrap();
                                for counterparty_node_id in pending_peers_awaiting_removal {
                                        match per_peer_state.entry(counterparty_node_id) {
                                                hash_map::Entry::Occupied(entry) => {
                                                        // Remove the entry if the peer is still disconnected and we still
                                                        // have no channels to the peer.
                                                        let remove_entry = {
                                                                let peer_state = entry.get().lock().unwrap();
                                                                peer_state.ok_to_remove(true)
                                                        };
                                                        if remove_entry {
                                                                entry.remove_entry();
                                                        }
                                                },
                                                hash_map::Entry::Vacant(_) => { /* The PeerState has already been removed */ }
                                        }
                                }
                        }

                        self.claimable_payments.lock().unwrap().claimable_payments.retain(|payment_hash, payment| {
                                if payment.htlcs.is_empty() {
                                        // This should be unreachable
                                        debug_assert!(false);
                                        return false;
                                }
                                if let OnionPayload::Invoice { .. } = payment.htlcs[0].onion_payload {
                                        // Check if we've received all the parts we need for an MPP (the value of the parts adds to total_msat).
                                        // In this case we're not going to handle any timeouts of the parts here.
                                        // This condition determining whether the MPP is complete here must match
                                        // exactly the condition used in `process_pending_htlc_forwards`.
                                        if payment.htlcs[0].total_msat <= payment.htlcs.iter()
                                                .fold(0, |total, htlc| total + htlc.sender_intended_value)
                                        {
                                                return true;
                                        } else if payment.htlcs.iter_mut().any(|htlc| {
                                                htlc.timer_ticks += 1;
                                                return htlc.timer_ticks >= MPP_TIMEOUT_TICKS
                                        }) {
                                                timed_out_mpp_htlcs.extend(payment.htlcs.drain(..)
                                                        .map(|htlc: ClaimableHTLC| (htlc.prev_hop, *payment_hash)));
                                                return false;
                                        }
                                }
                                true
                        });

                        for htlc_source in timed_out_mpp_htlcs.drain(..) {
                                let source = HTLCSource::PreviousHopData(htlc_source.0.clone());
                                let reason = HTLCFailReason::from_failure_code(23);
                                let receiver = HTLCDestination::FailedPayment { payment_hash: htlc_source.1 };
                                self.fail_htlc_backwards_internal(&source, &htlc_source.1, &reason, receiver);
                        }

                        for (err, counterparty_node_id) in handle_errors.drain(..) {
                                let _ = handle_error!(self, err, counterparty_node_id);
                        }

                        for shutdown_res in shutdown_channels {
                                self.finish_close_channel(shutdown_res);
                        }

                        #[cfg(feature = "std")]
                        let duration_since_epoch = std::time::SystemTime::now()
                                .duration_since(std::time::SystemTime::UNIX_EPOCH)
                                .expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
                        #[cfg(not(feature = "std"))]
                        let duration_since_epoch = Duration::from_secs(
                                self.highest_seen_timestamp.load(Ordering::Acquire).saturating_sub(7200) as u64
                        );

                        self.pending_outbound_payments.remove_stale_payments(
                                duration_since_epoch, &self.pending_events
                        );

                        // Technically we don't need to do this here, but if we have holding cell entries in a
                        // channel that need freeing, it's better to do that here and block a background task
                        // than block the message queueing pipeline.
                        if self.check_free_holding_cells() {
                                should_persist = NotifyOption::DoPersist;
                        }

                        should_persist
                });
        }

        /// Indicates that the preimage for payment_hash is unknown or the received amount is incorrect
        /// after a PaymentClaimable event, failing the HTLC back to its origin and freeing resources
        /// along the path (including in our own channel on which we received it).
        ///
        /// Note that in some cases around unclean shutdown, it is possible the payment may have
        /// already been claimed by you via [`ChannelManager::claim_funds`] prior to you seeing (a
        /// second copy of) the [`events::Event::PaymentClaimable`] event. Alternatively, the payment
        /// may have already been failed automatically by LDK if it was nearing its expiration time.
        ///
        /// While LDK will never claim a payment automatically on your behalf (i.e. without you calling
        /// [`ChannelManager::claim_funds`]), you should still monitor for
        /// [`events::Event::PaymentClaimed`] events even for payments you intend to fail, especially on
        /// startup during which time claims that were in-progress at shutdown may be replayed.
        pub fn fail_htlc_backwards(&self, payment_hash: &PaymentHash) {
                self.fail_htlc_backwards_with_reason(payment_hash, FailureCode::IncorrectOrUnknownPaymentDetails);
        }

        /// This is a variant of [`ChannelManager::fail_htlc_backwards`] that allows you to specify the
        /// reason for the failure.
        ///
        /// See [`FailureCode`] for valid failure codes.
        pub fn fail_htlc_backwards_with_reason(&self, payment_hash: &PaymentHash, failure_code: FailureCode) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let removed_source = self.claimable_payments.lock().unwrap().claimable_payments.remove(payment_hash);
                if let Some(payment) = removed_source {
                        for htlc in payment.htlcs {
                                let reason = self.get_htlc_fail_reason_from_failure_code(failure_code, &htlc);
                                let source = HTLCSource::PreviousHopData(htlc.prev_hop);
                                let receiver = HTLCDestination::FailedPayment { payment_hash: *payment_hash };
                                self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
                        }
                }
        }

        /// Gets error data to form an [`HTLCFailReason`] given a [`FailureCode`] and [`ClaimableHTLC`].
        fn get_htlc_fail_reason_from_failure_code(&self, failure_code: FailureCode, htlc: &ClaimableHTLC) -> HTLCFailReason {
                match failure_code {
                        FailureCode::TemporaryNodeFailure => HTLCFailReason::from_failure_code(failure_code.into()),
                        FailureCode::RequiredNodeFeatureMissing => HTLCFailReason::from_failure_code(failure_code.into()),
                        FailureCode::IncorrectOrUnknownPaymentDetails => {
                                let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
                                htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height().to_be_bytes());
                                HTLCFailReason::reason(failure_code.into(), htlc_msat_height_data)
                        },
                        FailureCode::InvalidOnionPayload(data) => {
                                let fail_data = match data {
                                        Some((typ, offset)) => [BigSize(typ).encode(), offset.encode()].concat(),
                                        None => Vec::new(),
                                };
                                HTLCFailReason::reason(failure_code.into(), fail_data)
                        }
                }
        }

        /// Gets an HTLC onion failure code and error data for an `UPDATE` error, given the error code
        /// that we want to return and a channel.
        ///
        /// This is for failures on the channel on which the HTLC was *received*, not failures
        /// forwarding
        fn get_htlc_inbound_temp_fail_err_and_data(&self, desired_err_code: u16, chan: &Channel<SP>) -> (u16, Vec<u8>) {
                // We can't be sure what SCID was used when relaying inbound towards us, so we have to
                // guess somewhat. If its a public channel, we figure best to just use the real SCID (as
                // we're not leaking that we have a channel with the counterparty), otherwise we try to use
                // an inbound SCID alias before the real SCID.
                let scid_pref = if chan.context.should_announce() {
                        chan.context.get_short_channel_id().or(chan.context.latest_inbound_scid_alias())
                } else {
                        chan.context.latest_inbound_scid_alias().or(chan.context.get_short_channel_id())
                };
                if let Some(scid) = scid_pref {
                        self.get_htlc_temp_fail_err_and_data(desired_err_code, scid, chan)
                } else {
                        (0x4000|10, Vec::new())
                }
        }


        /// Gets an HTLC onion failure code and error data for an `UPDATE` error, given the error code
        /// that we want to return and a channel.
        fn get_htlc_temp_fail_err_and_data(&self, desired_err_code: u16, scid: u64, chan: &Channel<SP>) -> (u16, Vec<u8>) {
                debug_assert_eq!(desired_err_code & 0x1000, 0x1000);
                if let Ok(upd) = self.get_channel_update_for_onion(scid, chan) {
                        let mut enc = VecWriter(Vec::with_capacity(upd.serialized_length() + 6));
                        if desired_err_code == 0x1000 | 20 {
                                // No flags for `disabled_flags` are currently defined so they're always two zero bytes.
                                // See https://github.com/lightning/bolts/blob/341ec84/04-onion-routing.md?plain=1#L1008
                                0u16.write(&mut enc).expect("Writes cannot fail");
                        }
                        (upd.serialized_length() as u16 + 2).write(&mut enc).expect("Writes cannot fail");
                        msgs::ChannelUpdate::TYPE.write(&mut enc).expect("Writes cannot fail");
                        upd.write(&mut enc).expect("Writes cannot fail");
                        (desired_err_code, enc.0)
                } else {
                        // If we fail to get a unicast channel_update, it implies we don't yet have an SCID,
                        // which means we really shouldn't have gotten a payment to be forwarded over this
                        // channel yet, or if we did it's from a route hint. Either way, returning an error of
                        // PERM|no_such_channel should be fine.
                        (0x4000|10, Vec::new())
                }
        }

        // Fail a list of HTLCs that were just freed from the holding cell. The HTLCs need to be
        // failed backwards or, if they were one of our outgoing HTLCs, then their failure needs to
        // be surfaced to the user.
        fn fail_holding_cell_htlcs(
                &self, mut htlcs_to_fail: Vec<(HTLCSource, PaymentHash)>, channel_id: ChannelId,
                counterparty_node_id: &PublicKey
        ) {
                let (failure_code, onion_failure_data) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        if let Some(peer_state_mutex) = per_peer_state.get(counterparty_node_id) {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                match peer_state.channel_by_id.entry(channel_id) {
                                        hash_map::Entry::Occupied(chan_phase_entry) => {
                                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get() {
                                                        self.get_htlc_inbound_temp_fail_err_and_data(0x1000|7, &chan)
                                                } else {
                                                        // We shouldn't be trying to fail holding cell HTLCs on an unfunded channel.
                                                        debug_assert!(false);
                                                        (0x4000|10, Vec::new())
                                                }
                                        },
                                        hash_map::Entry::Vacant(_) => (0x4000|10, Vec::new())
                                }
                        } else { (0x4000|10, Vec::new()) }
                };

                for (htlc_src, payment_hash) in htlcs_to_fail.drain(..) {
                        let reason = HTLCFailReason::reason(failure_code, onion_failure_data.clone());
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id.clone()), channel_id };
                        self.fail_htlc_backwards_internal(&htlc_src, &payment_hash, &reason, receiver);
                }
        }

        /// Fails an HTLC backwards to the sender of it to us.
        /// Note that we do not assume that channels corresponding to failed HTLCs are still available.
        fn fail_htlc_backwards_internal(&self, source: &HTLCSource, payment_hash: &PaymentHash, onion_error: &HTLCFailReason, destination: HTLCDestination) {
                // Ensure that no peer state channel storage lock is held when calling this function.
                // This ensures that future code doesn't introduce a lock-order requirement for
                // `forward_htlcs` to be locked after the `per_peer_state` peer locks, which calling
                // this function with any `per_peer_state` peer lock acquired would.
                #[cfg(debug_assertions)]
                for (_, peer) in self.per_peer_state.read().unwrap().iter() {
                        debug_assert_ne!(peer.held_by_thread(), LockHeldState::HeldByThread);
                }

                //TODO: There is a timing attack here where if a node fails an HTLC back to us they can
                //identify whether we sent it or not based on the (I presume) very different runtime
                //between the branches here. We should make this async and move it into the forward HTLCs
                //timer handling.

                // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
                // from block_connected which may run during initialization prior to the chain_monitor
                // being fully configured. See the docs for `ChannelManagerReadArgs` for more.
                match source {
                        HTLCSource::OutboundRoute { ref path, ref session_priv, ref payment_id, .. } => {
                                if self.pending_outbound_payments.fail_htlc(source, payment_hash, onion_error, path,
                                        session_priv, payment_id, self.probing_cookie_secret, &self.secp_ctx,
                                        &self.pending_events, &self.logger)
                                { self.push_pending_forwards_ev(); }
                        },
                        HTLCSource::PreviousHopData(HTLCPreviousHopData { ref short_channel_id, ref htlc_id, ref incoming_packet_shared_secret, ref phantom_shared_secret, ref outpoint, .. }) => {
                                log_trace!(self.logger, "Failing HTLC with payment_hash {} backwards from us with {:?}", &payment_hash, onion_error);
                                let err_packet = onion_error.get_encrypted_failure_packet(incoming_packet_shared_secret, phantom_shared_secret);

                                let mut push_forward_ev = false;
                                let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
                                if forward_htlcs.is_empty() {
                                        push_forward_ev = true;
                                }
                                match forward_htlcs.entry(*short_channel_id) {
                                        hash_map::Entry::Occupied(mut entry) => {
                                                entry.get_mut().push(HTLCForwardInfo::FailHTLC { htlc_id: *htlc_id, err_packet });
                                        },
                                        hash_map::Entry::Vacant(entry) => {
                                                entry.insert(vec!(HTLCForwardInfo::FailHTLC { htlc_id: *htlc_id, err_packet }));
                                        }
                                }
                                mem::drop(forward_htlcs);
                                if push_forward_ev { self.push_pending_forwards_ev(); }
                                let mut pending_events = self.pending_events.lock().unwrap();
                                pending_events.push_back((events::Event::HTLCHandlingFailed {
                                        prev_channel_id: outpoint.to_channel_id(),
                                        failed_next_destination: destination,
                                }, None));
                        },
                }
        }

        /// Provides a payment preimage in response to [`Event::PaymentClaimable`], generating any
        /// [`MessageSendEvent`]s needed to claim the payment.
        ///
        /// This method is guaranteed to ensure the payment has been claimed but only if the current
        /// height is strictly below [`Event::PaymentClaimable::claim_deadline`]. To avoid race
        /// conditions, you should wait for an [`Event::PaymentClaimed`] before considering the payment
        /// successful. It will generally be available in the next [`process_pending_events`] call.
        ///
        /// Note that if you did not set an `amount_msat` when calling [`create_inbound_payment`] or
        /// [`create_inbound_payment_for_hash`] you must check that the amount in the `PaymentClaimable`
        /// event matches your expectation. If you fail to do so and call this method, you may provide
        /// the sender "proof-of-payment" when they did not fulfill the full expected payment.
        ///
        /// This function will fail the payment if it has custom TLVs with even type numbers, as we
        /// will assume they are unknown. If you intend to accept even custom TLVs, you should use
        /// [`claim_funds_with_known_custom_tlvs`].
        ///
        /// [`Event::PaymentClaimable`]: crate::events::Event::PaymentClaimable
        /// [`Event::PaymentClaimable::claim_deadline`]: crate::events::Event::PaymentClaimable::claim_deadline
        /// [`Event::PaymentClaimed`]: crate::events::Event::PaymentClaimed
        /// [`process_pending_events`]: EventsProvider::process_pending_events
        /// [`create_inbound_payment`]: Self::create_inbound_payment
        /// [`create_inbound_payment_for_hash`]: Self::create_inbound_payment_for_hash
        /// [`claim_funds_with_known_custom_tlvs`]: Self::claim_funds_with_known_custom_tlvs
        pub fn claim_funds(&self, payment_preimage: PaymentPreimage) {
                self.claim_payment_internal(payment_preimage, false);
        }

        /// This is a variant of [`claim_funds`] that allows accepting a payment with custom TLVs with
        /// even type numbers.
        ///
        /// # Note
        ///
        /// You MUST check you've understood all even TLVs before using this to
        /// claim, otherwise you may unintentionally agree to some protocol you do not understand.
        ///
        /// [`claim_funds`]: Self::claim_funds
        pub fn claim_funds_with_known_custom_tlvs(&self, payment_preimage: PaymentPreimage) {
                self.claim_payment_internal(payment_preimage, true);
        }

        fn claim_payment_internal(&self, payment_preimage: PaymentPreimage, custom_tlvs_known: bool) {
                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).to_byte_array());

                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let mut sources = {
                        let mut claimable_payments = self.claimable_payments.lock().unwrap();
                        if let Some(payment) = claimable_payments.claimable_payments.remove(&payment_hash) {
                                let mut receiver_node_id = self.our_network_pubkey;
                                for htlc in payment.htlcs.iter() {
                                        if htlc.prev_hop.phantom_shared_secret.is_some() {
                                                let phantom_pubkey = self.node_signer.get_node_id(Recipient::PhantomNode)
                                                        .expect("Failed to get node_id for phantom node recipient");
                                                receiver_node_id = phantom_pubkey;
                                                break;
                                        }
                                }

                                let htlcs = payment.htlcs.iter().map(events::ClaimedHTLC::from).collect();
                                let sender_intended_value = payment.htlcs.first().map(|htlc| htlc.total_msat);
                                let dup_purpose = claimable_payments.pending_claiming_payments.insert(payment_hash,
                                        ClaimingPayment { amount_msat: payment.htlcs.iter().map(|source| source.value).sum(),
                                        payment_purpose: payment.purpose, receiver_node_id, htlcs, sender_intended_value
                                });
                                if dup_purpose.is_some() {
                                        debug_assert!(false, "Shouldn't get a duplicate pending claim event ever");
                                        log_error!(self.logger, "Got a duplicate pending claimable event on payment hash {}! Please report this bug",
                                                &payment_hash);
                                }

                                if let Some(RecipientOnionFields { ref custom_tlvs, .. }) = payment.onion_fields {
                                        if !custom_tlvs_known && custom_tlvs.iter().any(|(typ, _)| typ % 2 == 0) {
                                                log_info!(self.logger, "Rejecting payment with payment hash {} as we cannot accept payment with unknown even TLVs: {}",
                                                        &payment_hash, log_iter!(custom_tlvs.iter().map(|(typ, _)| typ).filter(|typ| *typ % 2 == 0)));
                                                claimable_payments.pending_claiming_payments.remove(&payment_hash);
                                                mem::drop(claimable_payments);
                                                for htlc in payment.htlcs {
                                                        let reason = self.get_htlc_fail_reason_from_failure_code(FailureCode::InvalidOnionPayload(None), &htlc);
                                                        let source = HTLCSource::PreviousHopData(htlc.prev_hop);
                                                        let receiver = HTLCDestination::FailedPayment { payment_hash };
                                                        self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
                                                }
                                                return;
                                        }
                                }

                                payment.htlcs
                        } else { return; }
                };
                debug_assert!(!sources.is_empty());

                // Just in case one HTLC has been failed between when we generated the `PaymentClaimable`
                // and when we got here we need to check that the amount we're about to claim matches the
                // amount we told the user in the last `PaymentClaimable`. We also do a sanity-check that
                // the MPP parts all have the same `total_msat`.
                let mut claimable_amt_msat = 0;
                let mut prev_total_msat = None;
                let mut expected_amt_msat = None;
                let mut valid_mpp = true;
                let mut errs = Vec::new();
                let per_peer_state = self.per_peer_state.read().unwrap();
                for htlc in sources.iter() {
                        if prev_total_msat.is_some() && prev_total_msat != Some(htlc.total_msat) {
                                log_error!(self.logger, "Somehow ended up with an MPP payment with different expected total amounts - this should not be reachable!");
                                debug_assert!(false);
                                valid_mpp = false;
                                break;
                        }
                        prev_total_msat = Some(htlc.total_msat);

                        if expected_amt_msat.is_some() && expected_amt_msat != htlc.total_value_received {
                                log_error!(self.logger, "Somehow ended up with an MPP payment with different received total amounts - this should not be reachable!");
                                debug_assert!(false);
                                valid_mpp = false;
                                break;
                        }
                        expected_amt_msat = htlc.total_value_received;
                        claimable_amt_msat += htlc.value;
                }
                mem::drop(per_peer_state);
                if sources.is_empty() || expected_amt_msat.is_none() {
                        self.claimable_payments.lock().unwrap().pending_claiming_payments.remove(&payment_hash);
                        log_info!(self.logger, "Attempted to claim an incomplete payment which no longer had any available HTLCs!");
                        return;
                }
                if claimable_amt_msat != expected_amt_msat.unwrap() {
                        self.claimable_payments.lock().unwrap().pending_claiming_payments.remove(&payment_hash);
                        log_info!(self.logger, "Attempted to claim an incomplete payment, expected {} msat, had {} available to claim.",
                                expected_amt_msat.unwrap(), claimable_amt_msat);
                        return;
                }
                if valid_mpp {
                        for htlc in sources.drain(..) {
                                if let Err((pk, err)) = self.claim_funds_from_hop(
                                        htlc.prev_hop, payment_preimage,
                                        |_, definitely_duplicate| {
                                                debug_assert!(!definitely_duplicate, "We shouldn't claim duplicatively from a payment");
                                                Some(MonitorUpdateCompletionAction::PaymentClaimed { payment_hash })
                                        }
                                ) {
                                        if let msgs::ErrorAction::IgnoreError = err.err.action {
                                                // We got a temporary failure updating monitor, but will claim the
                                                // HTLC when the monitor updating is restored (or on chain).
                                                log_error!(self.logger, "Temporary failure claiming HTLC, treating as success: {}", err.err.err);
                                        } else { errs.push((pk, err)); }
                                }
                        }
                }
                if !valid_mpp {
                        for htlc in sources.drain(..) {
                                let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
                                htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height().to_be_bytes());
                                let source = HTLCSource::PreviousHopData(htlc.prev_hop);
                                let reason = HTLCFailReason::reason(0x4000 | 15, htlc_msat_height_data);
                                let receiver = HTLCDestination::FailedPayment { payment_hash };
                                self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
                        }
                        self.claimable_payments.lock().unwrap().pending_claiming_payments.remove(&payment_hash);
                }

                // Now we can handle any errors which were generated.
                for (counterparty_node_id, err) in errs.drain(..) {
                        let res: Result<(), _> = Err(err);
                        let _ = handle_error!(self, res, counterparty_node_id);
                }
        }

        fn claim_funds_from_hop<ComplFunc: FnOnce(Option<u64>, bool) -> Option<MonitorUpdateCompletionAction>>(&self,
                prev_hop: HTLCPreviousHopData, payment_preimage: PaymentPreimage, completion_action: ComplFunc)
        -> Result<(), (PublicKey, MsgHandleErrInternal)> {
                //TODO: Delay the claimed_funds relaying just like we do outbound relay!

                // If we haven't yet run background events assume we're still deserializing and shouldn't
                // actually pass `ChannelMonitorUpdate`s to users yet. Instead, queue them up as
                // `BackgroundEvent`s.
                let during_init = !self.background_events_processed_since_startup.load(Ordering::Acquire);

                // As we may call handle_monitor_update_completion_actions in rather rare cases, check that
                // the required mutexes are not held before we start.
                debug_assert_ne!(self.pending_events.held_by_thread(), LockHeldState::HeldByThread);
                debug_assert_ne!(self.claimable_payments.held_by_thread(), LockHeldState::HeldByThread);

                {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let chan_id = prev_hop.outpoint.to_channel_id();
                        let counterparty_node_id_opt = match self.short_to_chan_info.read().unwrap().get(&prev_hop.short_channel_id) {
                                Some((cp_id, _dup_chan_id)) => Some(cp_id.clone()),
                                None => None
                        };

                        let peer_state_opt = counterparty_node_id_opt.as_ref().map(
                                |counterparty_node_id| per_peer_state.get(counterparty_node_id)
                                        .map(|peer_mutex| peer_mutex.lock().unwrap())
                        ).unwrap_or(None);

                        if peer_state_opt.is_some() {
                                let mut peer_state_lock = peer_state_opt.unwrap();
                                let peer_state = &mut *peer_state_lock;
                                if let hash_map::Entry::Occupied(mut chan_phase_entry) = peer_state.channel_by_id.entry(chan_id) {
                                        if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                                let counterparty_node_id = chan.context.get_counterparty_node_id();
                                                let fulfill_res = chan.get_update_fulfill_htlc_and_commit(prev_hop.htlc_id, payment_preimage, &self.logger);

                                                match fulfill_res {
                                                        UpdateFulfillCommitFetch::NewClaim { htlc_value_msat, monitor_update } => {
                                                                if let Some(action) = completion_action(Some(htlc_value_msat), false) {
                                                                        log_trace!(self.logger, "Tracking monitor update completion action for channel {}: {:?}",
                                                                                chan_id, action);
                                                                        peer_state.monitor_update_blocked_actions.entry(chan_id).or_insert(Vec::new()).push(action);
                                                                }
                                                                if !during_init {
                                                                        handle_new_monitor_update!(self, prev_hop.outpoint, monitor_update, peer_state_lock,
                                                                                peer_state, per_peer_state, chan);
                                                                } else {
                                                                        // If we're running during init we cannot update a monitor directly -
                                                                        // they probably haven't actually been loaded yet. Instead, push the
                                                                        // monitor update as a background event.
                                                                        self.pending_background_events.lock().unwrap().push(
                                                                                BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
                                                                                        counterparty_node_id,
                                                                                        funding_txo: prev_hop.outpoint,
                                                                                        update: monitor_update.clone(),
                                                                                });
                                                                }
                                                        }
                                                        UpdateFulfillCommitFetch::DuplicateClaim {} => {
                                                                let action = if let Some(action) = completion_action(None, true) {
                                                                        action
                                                                } else {
                                                                        return Ok(());
                                                                };
                                                                mem::drop(peer_state_lock);

                                                                log_trace!(self.logger, "Completing monitor update completion action for channel {} as claim was redundant: {:?}",
                                                                        chan_id, action);
                                                                let (node_id, funding_outpoint, blocker) =
                                                                if let MonitorUpdateCompletionAction::FreeOtherChannelImmediately {
                                                                        downstream_counterparty_node_id: node_id,
                                                                        downstream_funding_outpoint: funding_outpoint,
                                                                        blocking_action: blocker,
                                                                } = action {
                                                                        (node_id, funding_outpoint, blocker)
                                                                } else {
                                                                        debug_assert!(false,
                                                                                "Duplicate claims should always free another channel immediately");
                                                                        return Ok(());
                                                                };
                                                                if let Some(peer_state_mtx) = per_peer_state.get(&node_id) {
                                                                        let mut peer_state = peer_state_mtx.lock().unwrap();
                                                                        if let Some(blockers) = peer_state
                                                                                .actions_blocking_raa_monitor_updates
                                                                                .get_mut(&funding_outpoint.to_channel_id())
                                                                        {
                                                                                let mut found_blocker = false;
                                                                                blockers.retain(|iter| {
                                                                                        // Note that we could actually be blocked, in
                                                                                        // which case we need to only remove the one
                                                                                        // blocker which was added duplicatively.
                                                                                        let first_blocker = !found_blocker;
                                                                                        if *iter == blocker { found_blocker = true; }
                                                                                        *iter != blocker || !first_blocker
                                                                                });
                                                                                debug_assert!(found_blocker);
                                                                        }
                                                                } else {
                                                                        debug_assert!(false);
                                                                }
                                                        }
                                                }
                                        }
                                        return Ok(());
                                }
                        }
                }
                let preimage_update = ChannelMonitorUpdate {
                        update_id: CLOSED_CHANNEL_UPDATE_ID,
                        updates: vec![ChannelMonitorUpdateStep::PaymentPreimage {
                                payment_preimage,
                        }],
                };

                if !during_init {
                        // We update the ChannelMonitor on the backward link, after
                        // receiving an `update_fulfill_htlc` from the forward link.
                        let update_res = self.chain_monitor.update_channel(prev_hop.outpoint, &preimage_update);
                        if update_res != ChannelMonitorUpdateStatus::Completed {
                                // TODO: This needs to be handled somehow - if we receive a monitor update
                                // with a preimage we *must* somehow manage to propagate it to the upstream
                                // channel, or we must have an ability to receive the same event and try
                                // again on restart.
                                log_error!(self.logger, "Critical error: failed to update channel monitor with preimage {:?}: {:?}",
                                        payment_preimage, update_res);
                        }
                } else {
                        // If we're running during init we cannot update a monitor directly - they probably
                        // haven't actually been loaded yet. Instead, push the monitor update as a background
                        // event.
                        // Note that while it's safe to use `ClosedMonitorUpdateRegeneratedOnStartup` here (the
                        // channel is already closed) we need to ultimately handle the monitor update
                        // completion action only after we've completed the monitor update. This is the only
                        // way to guarantee this update *will* be regenerated on startup (otherwise if this was
                        // from a forwarded HTLC the downstream preimage may be deleted before we claim
                        // upstream). Thus, we need to transition to some new `BackgroundEvent` type which will
                        // complete the monitor update completion action from `completion_action`.
                        self.pending_background_events.lock().unwrap().push(
                                BackgroundEvent::ClosedMonitorUpdateRegeneratedOnStartup((
                                        prev_hop.outpoint, preimage_update,
                                )));
                }
                // Note that we do process the completion action here. This totally could be a
                // duplicate claim, but we have no way of knowing without interrogating the
                // `ChannelMonitor` we've provided the above update to. Instead, note that `Event`s are
                // generally always allowed to be duplicative (and it's specifically noted in
                // `PaymentForwarded`).
                self.handle_monitor_update_completion_actions(completion_action(None, false));
                Ok(())
        }

        fn finalize_claims(&self, sources: Vec<HTLCSource>) {
                self.pending_outbound_payments.finalize_claims(sources, &self.pending_events);
        }

        fn claim_funds_internal(&self, source: HTLCSource, payment_preimage: PaymentPreimage,
                forwarded_htlc_value_msat: Option<u64>, from_onchain: bool, startup_replay: bool,
                next_channel_counterparty_node_id: Option<PublicKey>, next_channel_outpoint: OutPoint
        ) {
                match source {
                        HTLCSource::OutboundRoute { session_priv, payment_id, path, .. } => {
                                debug_assert!(self.background_events_processed_since_startup.load(Ordering::Acquire),
                                        "We don't support claim_htlc claims during startup - monitors may not be available yet");
                                if let Some(pubkey) = next_channel_counterparty_node_id {
                                        debug_assert_eq!(pubkey, path.hops[0].pubkey);
                                }
                                let ev_completion_action = EventCompletionAction::ReleaseRAAChannelMonitorUpdate {
                                        channel_funding_outpoint: next_channel_outpoint,
                                        counterparty_node_id: path.hops[0].pubkey,
                                };
                                self.pending_outbound_payments.claim_htlc(payment_id, payment_preimage,
                                        session_priv, path, from_onchain, ev_completion_action, &self.pending_events,
                                        &self.logger);
                        },
                        HTLCSource::PreviousHopData(hop_data) => {
                                let prev_outpoint = hop_data.outpoint;
                                let completed_blocker = RAAMonitorUpdateBlockingAction::from_prev_hop_data(&hop_data);
                                #[cfg(debug_assertions)]
                                let claiming_chan_funding_outpoint = hop_data.outpoint;
                                let res = self.claim_funds_from_hop(hop_data, payment_preimage,
                                        |htlc_claim_value_msat, definitely_duplicate| {
                                                let chan_to_release =
                                                        if let Some(node_id) = next_channel_counterparty_node_id {
                                                                Some((node_id, next_channel_outpoint, completed_blocker))
                                                        } else {
                                                                // We can only get `None` here if we are processing a
                                                                // `ChannelMonitor`-originated event, in which case we
                                                                // don't care about ensuring we wake the downstream
                                                                // channel's monitor updating - the channel is already
                                                                // closed.
                                                                None
                                                        };

                                                if definitely_duplicate && startup_replay {
                                                        // On startup we may get redundant claims which are related to
                                                        // monitor updates still in flight. In that case, we shouldn't
                                                        // immediately free, but instead let that monitor update complete
                                                        // in the background.
                                                        #[cfg(debug_assertions)] {
                                                                let background_events = self.pending_background_events.lock().unwrap();
                                                                // There should be a `BackgroundEvent` pending...
                                                                assert!(background_events.iter().any(|ev| {
                                                                        match ev {
                                                                                // to apply a monitor update that blocked the claiming channel,
                                                                                BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
                                                                                        funding_txo, update, ..
                                                                                } => {
                                                                                        if *funding_txo == claiming_chan_funding_outpoint {
                                                                                                assert!(update.updates.iter().any(|upd|
                                                                                                        if let ChannelMonitorUpdateStep::PaymentPreimage {
                                                                                                                payment_preimage: update_preimage
                                                                                                        } = upd {
                                                                                                                payment_preimage == *update_preimage
                                                                                                        } else { false }
                                                                                                ), "{:?}", update);
                                                                                                true
                                                                                        } else { false }
                                                                                },
                                                                                // or the channel we'd unblock is already closed,
                                                                                BackgroundEvent::ClosedMonitorUpdateRegeneratedOnStartup(
                                                                                        (funding_txo, monitor_update)
                                                                                ) => {
                                                                                        if *funding_txo == next_channel_outpoint {
                                                                                                assert_eq!(monitor_update.updates.len(), 1);
                                                                                                assert!(matches!(
                                                                                                        monitor_update.updates[0],
                                                                                                        ChannelMonitorUpdateStep::ChannelForceClosed { .. }
                                                                                                ));
                                                                                                true
                                                                                        } else { false }
                                                                                },
                                                                                // or the monitor update has completed and will unblock
                                                                                // immediately once we get going.
                                                                                BackgroundEvent::MonitorUpdatesComplete {
                                                                                        channel_id, ..
                                                                                } =>
                                                                                        *channel_id == claiming_chan_funding_outpoint.to_channel_id(),
                                                                        }
                                                                }), "{:?}", *background_events);
                                                        }
                                                        None
                                                } else if definitely_duplicate {
                                                        if let Some(other_chan) = chan_to_release {
                                                                Some(MonitorUpdateCompletionAction::FreeOtherChannelImmediately {
                                                                        downstream_counterparty_node_id: other_chan.0,
                                                                        downstream_funding_outpoint: other_chan.1,
                                                                        blocking_action: other_chan.2,
                                                                })
                                                        } else { None }
                                                } else {
                                                        let fee_earned_msat = if let Some(forwarded_htlc_value) = forwarded_htlc_value_msat {
                                                                if let Some(claimed_htlc_value) = htlc_claim_value_msat {
                                                                        Some(claimed_htlc_value - forwarded_htlc_value)
                                                                } else { None }
                                                        } else { None };
                                                        Some(MonitorUpdateCompletionAction::EmitEventAndFreeOtherChannel {
                                                                event: events::Event::PaymentForwarded {
                                                                        fee_earned_msat,
                                                                        claim_from_onchain_tx: from_onchain,
                                                                        prev_channel_id: Some(prev_outpoint.to_channel_id()),
                                                                        next_channel_id: Some(next_channel_outpoint.to_channel_id()),
                                                                        outbound_amount_forwarded_msat: forwarded_htlc_value_msat,
                                                                },
                                                                downstream_counterparty_and_funding_outpoint: chan_to_release,
                                                        })
                                                }
                                        });
                                if let Err((pk, err)) = res {
                                        let result: Result<(), _> = Err(err);
                                        let _ = handle_error!(self, result, pk);
                                }
                        },
                }
        }

        /// Gets the node_id held by this ChannelManager
        pub fn get_our_node_id(&self) -> PublicKey {
                self.our_network_pubkey.clone()
        }

        fn handle_monitor_update_completion_actions<I: IntoIterator<Item=MonitorUpdateCompletionAction>>(&self, actions: I) {
                debug_assert_ne!(self.pending_events.held_by_thread(), LockHeldState::HeldByThread);
                debug_assert_ne!(self.claimable_payments.held_by_thread(), LockHeldState::HeldByThread);
                debug_assert_ne!(self.per_peer_state.held_by_thread(), LockHeldState::HeldByThread);

                for action in actions.into_iter() {
                        match action {
                                MonitorUpdateCompletionAction::PaymentClaimed { payment_hash } => {
                                        let payment = self.claimable_payments.lock().unwrap().pending_claiming_payments.remove(&payment_hash);
                                        if let Some(ClaimingPayment {
                                                amount_msat,
                                                payment_purpose: purpose,
                                                receiver_node_id,
                                                htlcs,
                                                sender_intended_value: sender_intended_total_msat,
                                        }) = payment {
                                                self.pending_events.lock().unwrap().push_back((events::Event::PaymentClaimed {
                                                        payment_hash,
                                                        purpose,
                                                        amount_msat,
                                                        receiver_node_id: Some(receiver_node_id),
                                                        htlcs,
                                                        sender_intended_total_msat,
                                                }, None));
                                        }
                                },
                                MonitorUpdateCompletionAction::EmitEventAndFreeOtherChannel {
                                        event, downstream_counterparty_and_funding_outpoint
                                } => {
                                        self.pending_events.lock().unwrap().push_back((event, None));
                                        if let Some((node_id, funding_outpoint, blocker)) = downstream_counterparty_and_funding_outpoint {
                                                self.handle_monitor_update_release(node_id, funding_outpoint, Some(blocker));
                                        }
                                },
                                MonitorUpdateCompletionAction::FreeOtherChannelImmediately {
                                        downstream_counterparty_node_id, downstream_funding_outpoint, blocking_action,
                                } => {
                                        self.handle_monitor_update_release(
                                                downstream_counterparty_node_id,
                                                downstream_funding_outpoint,
                                                Some(blocking_action),
                                        );
                                },
                        }
                }
        }

        /// Handles a channel reentering a functional state, either due to reconnect or a monitor
        /// update completion.
        fn handle_channel_resumption(&self, pending_msg_events: &mut Vec<MessageSendEvent>,
                channel: &mut Channel<SP>, raa: Option<msgs::RevokeAndACK>,
                commitment_update: Option<msgs::CommitmentUpdate>, order: RAACommitmentOrder,
                pending_forwards: Vec<(PendingHTLCInfo, u64)>, funding_broadcastable: Option<Transaction>,
                channel_ready: Option<msgs::ChannelReady>, announcement_sigs: Option<msgs::AnnouncementSignatures>)
        -> Option<(u64, OutPoint, u128, Vec<(PendingHTLCInfo, u64)>)> {
                log_trace!(self.logger, "Handling channel resumption for channel {} with {} RAA, {} commitment update, {} pending forwards, {}broadcasting funding, {} channel ready, {} announcement",
                        &channel.context.channel_id(),
                        if raa.is_some() { "an" } else { "no" },
                        if commitment_update.is_some() { "a" } else { "no" }, pending_forwards.len(),
                        if funding_broadcastable.is_some() { "" } else { "not " },
                        if channel_ready.is_some() { "sending" } else { "without" },
                        if announcement_sigs.is_some() { "sending" } else { "without" });

                let mut htlc_forwards = None;

                let counterparty_node_id = channel.context.get_counterparty_node_id();
                if !pending_forwards.is_empty() {
                        htlc_forwards = Some((channel.context.get_short_channel_id().unwrap_or(channel.context.outbound_scid_alias()),
                                channel.context.get_funding_txo().unwrap(), channel.context.get_user_id(), pending_forwards));
                }

                if let Some(msg) = channel_ready {
                        send_channel_ready!(self, pending_msg_events, channel, msg);
                }
                if let Some(msg) = announcement_sigs {
                        pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                node_id: counterparty_node_id,
                                msg,
                        });
                }

                macro_rules! handle_cs { () => {
                        if let Some(update) = commitment_update {
                                pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                        node_id: counterparty_node_id,
                                        updates: update,
                                });
                        }
                } }
                macro_rules! handle_raa { () => {
                        if let Some(revoke_and_ack) = raa {
                                pending_msg_events.push(events::MessageSendEvent::SendRevokeAndACK {
                                        node_id: counterparty_node_id,
                                        msg: revoke_and_ack,
                                });
                        }
                } }
                match order {
                        RAACommitmentOrder::CommitmentFirst => {
                                handle_cs!();
                                handle_raa!();
                        },
                        RAACommitmentOrder::RevokeAndACKFirst => {
                                handle_raa!();
                                handle_cs!();
                        },
                }

                if let Some(tx) = funding_broadcastable {
                        log_info!(self.logger, "Broadcasting funding transaction with txid {}", tx.txid());
                        self.tx_broadcaster.broadcast_transactions(&[&tx]);
                }

                {
                        let mut pending_events = self.pending_events.lock().unwrap();
                        emit_channel_pending_event!(pending_events, channel);
                        emit_channel_ready_event!(pending_events, channel);
                }

                htlc_forwards
        }

        fn channel_monitor_updated(&self, funding_txo: &OutPoint, highest_applied_update_id: u64, counterparty_node_id: Option<&PublicKey>) {
                debug_assert!(self.total_consistency_lock.try_write().is_err()); // Caller holds read lock

                let counterparty_node_id = match counterparty_node_id {
                        Some(cp_id) => cp_id.clone(),
                        None => {
                                // TODO: Once we can rely on the counterparty_node_id from the
                                // monitor event, this and the id_to_peer map should be removed.
                                let id_to_peer = self.id_to_peer.lock().unwrap();
                                match id_to_peer.get(&funding_txo.to_channel_id()) {
                                        Some(cp_id) => cp_id.clone(),
                                        None => return,
                                }
                        }
                };
                let per_peer_state = self.per_peer_state.read().unwrap();
                let mut peer_state_lock;
                let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
                if peer_state_mutex_opt.is_none() { return }
                peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                let channel =
                        if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get_mut(&funding_txo.to_channel_id()) {
                                chan
                        } else {
                                let update_actions = peer_state.monitor_update_blocked_actions
                                        .remove(&funding_txo.to_channel_id()).unwrap_or(Vec::new());
                                mem::drop(peer_state_lock);
                                mem::drop(per_peer_state);
                                self.handle_monitor_update_completion_actions(update_actions);
                                return;
                        };
                let remaining_in_flight =
                        if let Some(pending) = peer_state.in_flight_monitor_updates.get_mut(funding_txo) {
                                pending.retain(|upd| upd.update_id > highest_applied_update_id);
                                pending.len()
                        } else { 0 };
                log_trace!(self.logger, "ChannelMonitor updated to {}. Current highest is {}. {} pending in-flight updates.",
                        highest_applied_update_id, channel.context.get_latest_monitor_update_id(),
                        remaining_in_flight);
                if !channel.is_awaiting_monitor_update() || channel.context.get_latest_monitor_update_id() != highest_applied_update_id {
                        return;
                }
                handle_monitor_update_completion!(self, peer_state_lock, peer_state, per_peer_state, channel);
        }

        /// Accepts a request to open a channel after a [`Event::OpenChannelRequest`].
        ///
        /// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
        /// and the `counterparty_node_id` parameter is the id of the peer which has requested to open
        /// the channel.
        ///
        /// The `user_channel_id` parameter will be provided back in
        /// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
        /// with which `accept_inbound_channel`/`accept_inbound_channel_from_trusted_peer_0conf` call.
        ///
        /// Note that this method will return an error and reject the channel, if it requires support
        /// for zero confirmations. Instead, `accept_inbound_channel_from_trusted_peer_0conf` must be
        /// used to accept such channels.
        ///
        /// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
        /// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
        pub fn accept_inbound_channel(&self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, user_channel_id: u128) -> Result<(), APIError> {
                self.do_accept_inbound_channel(temporary_channel_id, counterparty_node_id, false, user_channel_id)
        }

        /// Accepts a request to open a channel after a [`events::Event::OpenChannelRequest`], treating
        /// it as confirmed immediately.
        ///
        /// The `user_channel_id` parameter will be provided back in
        /// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
        /// with which `accept_inbound_channel`/`accept_inbound_channel_from_trusted_peer_0conf` call.
        ///
        /// Unlike [`ChannelManager::accept_inbound_channel`], this method accepts the incoming channel
        /// and (if the counterparty agrees), enables forwarding of payments immediately.
        ///
        /// This fully trusts that the counterparty has honestly and correctly constructed the funding
        /// transaction and blindly assumes that it will eventually confirm.
        ///
        /// If it does not confirm before we decide to close the channel, or if the funding transaction
        /// does not pay to the correct script the correct amount, *you will lose funds*.
        ///
        /// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
        /// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
        pub fn accept_inbound_channel_from_trusted_peer_0conf(&self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, user_channel_id: u128) -> Result<(), APIError> {
                self.do_accept_inbound_channel(temporary_channel_id, counterparty_node_id, true, user_channel_id)
        }

        fn do_accept_inbound_channel(&self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool, user_channel_id: u128) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let peers_without_funded_channels =
                        self.peers_without_funded_channels(|peer| { peer.total_channel_count() > 0 });
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                let is_only_peer_channel = peer_state.total_channel_count() == 1;

                // Find (and remove) the channel in the unaccepted table. If it's not there, something weird is
                // happening and return an error. N.B. that we create channel with an outbound SCID of zero so
                // that we can delay allocating the SCID until after we're sure that the checks below will
                // succeed.
                let mut channel = match peer_state.inbound_channel_request_by_id.remove(temporary_channel_id) {
                        Some(unaccepted_channel) => {
                                let best_block_height = self.best_block.read().unwrap().height();
                                InboundV1Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider,
                                        counterparty_node_id.clone(), &self.channel_type_features(), &peer_state.latest_features,
                                        &unaccepted_channel.open_channel_msg, user_channel_id, &self.default_configuration, best_block_height,
                                        &self.logger, accept_0conf).map_err(|e| APIError::ChannelUnavailable { err: e.to_string() })
                        }
                        _ => Err(APIError::APIMisuseError { err: "No such channel awaiting to be accepted.".to_owned() })
                }?;

                if accept_0conf {
                        // This should have been correctly configured by the call to InboundV1Channel::new.
                        debug_assert!(channel.context.minimum_depth().unwrap() == 0);
                } else if channel.context.get_channel_type().requires_zero_conf() {
                        let send_msg_err_event = events::MessageSendEvent::HandleError {
                                node_id: channel.context.get_counterparty_node_id(),
                                action: msgs::ErrorAction::SendErrorMessage{
                                        msg: msgs::ErrorMessage { channel_id: temporary_channel_id.clone(), data: "No zero confirmation channels accepted".to_owned(), }
                                }
                        };
                        peer_state.pending_msg_events.push(send_msg_err_event);
                        return Err(APIError::APIMisuseError { err: "Please use accept_inbound_channel_from_trusted_peer_0conf to accept channels with zero confirmations.".to_owned() });
                } else {
                        // If this peer already has some channels, a new channel won't increase our number of peers
                        // with unfunded channels, so as long as we aren't over the maximum number of unfunded
                        // channels per-peer we can accept channels from a peer with existing ones.
                        if is_only_peer_channel && peers_without_funded_channels >= MAX_UNFUNDED_CHANNEL_PEERS {
                                let send_msg_err_event = events::MessageSendEvent::HandleError {
                                        node_id: channel.context.get_counterparty_node_id(),
                                        action: msgs::ErrorAction::SendErrorMessage{
                                                msg: msgs::ErrorMessage { channel_id: temporary_channel_id.clone(), data: "Have too many peers with unfunded channels, not accepting new ones".to_owned(), }
                                        }
                                };
                                peer_state.pending_msg_events.push(send_msg_err_event);
                                return Err(APIError::APIMisuseError { err: "Too many peers with unfunded channels, refusing to accept new ones".to_owned() });
                        }
                }

                // Now that we know we have a channel, assign an outbound SCID alias.
                let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                channel.context.set_outbound_scid_alias(outbound_scid_alias);

                peer_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
                        node_id: channel.context.get_counterparty_node_id(),
                        msg: channel.accept_inbound_channel(),
                });

                peer_state.channel_by_id.insert(temporary_channel_id.clone(), ChannelPhase::UnfundedInboundV1(channel));

                Ok(())
        }

        /// Gets the number of peers which match the given filter and do not have any funded, outbound,
        /// or 0-conf channels.
        ///
        /// The filter is called for each peer and provided with the number of unfunded, inbound, and
        /// non-0-conf channels we have with the peer.
        fn peers_without_funded_channels<Filter>(&self, maybe_count_peer: Filter) -> usize
        where Filter: Fn(&PeerState<SP>) -> bool {
                let mut peers_without_funded_channels = 0;
                let best_block_height = self.best_block.read().unwrap().height();
                {
                        let peer_state_lock = self.per_peer_state.read().unwrap();
                        for (_, peer_mtx) in peer_state_lock.iter() {
                                let peer = peer_mtx.lock().unwrap();
                                if !maybe_count_peer(&*peer) { continue; }
                                let num_unfunded_channels = Self::unfunded_channel_count(&peer, best_block_height);
                                if num_unfunded_channels == peer.total_channel_count() {
                                        peers_without_funded_channels += 1;
                                }
                        }
                }
                return peers_without_funded_channels;
        }

        fn unfunded_channel_count(
                peer: &PeerState<SP>, best_block_height: u32
        ) -> usize {
                let mut num_unfunded_channels = 0;
                for (_, phase) in peer.channel_by_id.iter() {
                        match phase {
                                ChannelPhase::Funded(chan) => {
                                        // This covers non-zero-conf inbound `Channel`s that we are currently monitoring, but those
                                        // which have not yet had any confirmations on-chain.
                                        if !chan.context.is_outbound() && chan.context.minimum_depth().unwrap_or(1) != 0 &&
                                                chan.context.get_funding_tx_confirmations(best_block_height) == 0
                                        {
                                                num_unfunded_channels += 1;
                                        }
                                },
                                ChannelPhase::UnfundedInboundV1(chan) => {
                                        if chan.context.minimum_depth().unwrap_or(1) != 0 {
                                                num_unfunded_channels += 1;
                                        }
                                },
                                ChannelPhase::UnfundedOutboundV1(_) => {
                                        // Outbound channels don't contribute to the unfunded count in the DoS context.
                                        continue;
                                }
                        }
                }
                num_unfunded_channels + peer.inbound_channel_request_by_id.len()
        }

        fn internal_open_channel(&self, counterparty_node_id: &PublicKey, msg: &msgs::OpenChannel) -> Result<(), MsgHandleErrInternal> {
                // Note that the ChannelManager is NOT re-persisted on disk after this, so any changes are
                // likely to be lost on restart!
                if msg.chain_hash != self.chain_hash {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Unknown genesis block hash".to_owned(), msg.temporary_channel_id.clone()));
                }

                if !self.default_configuration.accept_inbound_channels {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close("No inbound channels accepted".to_owned(), msg.temporary_channel_id.clone()));
                }

                // Get the number of peers with channels, but without funded ones. We don't care too much
                // about peers that never open a channel, so we filter by peers that have at least one
                // channel, and then limit the number of those with unfunded channels.
                let channeled_peers_without_funding =
                        self.peers_without_funded_channels(|node| node.total_channel_count() > 0);

                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                    .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id.clone())
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;

                // If this peer already has some channels, a new channel won't increase our number of peers
                // with unfunded channels, so as long as we aren't over the maximum number of unfunded
                // channels per-peer we can accept channels from a peer with existing ones.
                if peer_state.total_channel_count() == 0 &&
                        channeled_peers_without_funding >= MAX_UNFUNDED_CHANNEL_PEERS &&
                        !self.default_configuration.manually_accept_inbound_channels
                {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close(
                                "Have too many peers with unfunded channels, not accepting new ones".to_owned(),
                                msg.temporary_channel_id.clone()));
                }

                let best_block_height = self.best_block.read().unwrap().height();
                if Self::unfunded_channel_count(peer_state, best_block_height) >= MAX_UNFUNDED_CHANS_PER_PEER {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close(
                                format!("Refusing more than {} unfunded channels.", MAX_UNFUNDED_CHANS_PER_PEER),
                                msg.temporary_channel_id.clone()));
                }

                let channel_id = msg.temporary_channel_id;
                let channel_exists = peer_state.has_channel(&channel_id);
                if channel_exists {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close("temporary_channel_id collision for the same peer!".to_owned(), msg.temporary_channel_id.clone()));
                }

                // If we're doing manual acceptance checks on the channel, then defer creation until we're sure we want to accept.
                if self.default_configuration.manually_accept_inbound_channels {
                        let mut pending_events = self.pending_events.lock().unwrap();
                        pending_events.push_back((events::Event::OpenChannelRequest {
                                temporary_channel_id: msg.temporary_channel_id.clone(),
                                counterparty_node_id: counterparty_node_id.clone(),
                                funding_satoshis: msg.funding_satoshis,
                                push_msat: msg.push_msat,
                                channel_type: msg.channel_type.clone().unwrap(),
                        }, None));
                        peer_state.inbound_channel_request_by_id.insert(channel_id, InboundChannelRequest {
                                open_channel_msg: msg.clone(),
                                ticks_remaining: UNACCEPTED_INBOUND_CHANNEL_AGE_LIMIT_TICKS,
                        });
                        return Ok(());
                }

                // Otherwise create the channel right now.
                let mut random_bytes = [0u8; 16];
                random_bytes.copy_from_slice(&self.entropy_source.get_secure_random_bytes()[..16]);
                let user_channel_id = u128::from_be_bytes(random_bytes);
                let mut channel = match InboundV1Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider,
                        counterparty_node_id.clone(), &self.channel_type_features(), &peer_state.latest_features, msg, user_channel_id,
                        &self.default_configuration, best_block_height, &self.logger, /*is_0conf=*/false)
                {
                        Err(e) => {
                                return Err(MsgHandleErrInternal::from_chan_no_close(e, msg.temporary_channel_id));
                        },
                        Ok(res) => res
                };

                let channel_type = channel.context.get_channel_type();
                if channel_type.requires_zero_conf() {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close("No zero confirmation channels accepted".to_owned(), msg.temporary_channel_id.clone()));
                }
                if channel_type.requires_anchors_zero_fee_htlc_tx() {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close("No channels with anchor outputs accepted".to_owned(), msg.temporary_channel_id.clone()));
                }

                let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                channel.context.set_outbound_scid_alias(outbound_scid_alias);

                peer_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
                        node_id: counterparty_node_id.clone(),
                        msg: channel.accept_inbound_channel(),
                });
                peer_state.channel_by_id.insert(channel_id, ChannelPhase::UnfundedInboundV1(channel));
                Ok(())
        }

        fn internal_accept_channel(&self, counterparty_node_id: &PublicKey, msg: &msgs::AcceptChannel) -> Result<(), MsgHandleErrInternal> {
                // Note that the ChannelManager is NOT re-persisted on disk after this, so any changes are
                // likely to be lost on restart!
                let (value, output_script, user_id) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                                .ok_or_else(|| {
                                        debug_assert!(false);
                                        MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id)
                                })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.temporary_channel_id) {
                                hash_map::Entry::Occupied(mut phase) => {
                                        match phase.get_mut() {
                                                ChannelPhase::UnfundedOutboundV1(chan) => {
                                                        try_chan_phase_entry!(self, chan.accept_channel(&msg, &self.default_configuration.channel_handshake_limits, &peer_state.latest_features), phase);
                                                        (chan.context.get_value_satoshis(), chan.context.get_funding_redeemscript().to_v0_p2wsh(), chan.context.get_user_id())
                                                },
                                                _ => {
                                                        return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got an unexpected accept_channel message from peer with counterparty_node_id {}", counterparty_node_id), msg.temporary_channel_id));
                                                }
                                        }
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.temporary_channel_id))
                        }
                };
                let mut pending_events = self.pending_events.lock().unwrap();
                pending_events.push_back((events::Event::FundingGenerationReady {
                        temporary_channel_id: msg.temporary_channel_id,
                        counterparty_node_id: *counterparty_node_id,
                        channel_value_satoshis: value,
                        output_script,
                        user_channel_id: user_id,
                }, None));
                Ok(())
        }

        fn internal_funding_created(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingCreated) -> Result<(), MsgHandleErrInternal> {
                let best_block = *self.best_block.read().unwrap();

                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id)
                        })?;

                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                let (chan, funding_msg_opt, monitor) =
                        match peer_state.channel_by_id.remove(&msg.temporary_channel_id) {
                                Some(ChannelPhase::UnfundedInboundV1(inbound_chan)) => {
                                        match inbound_chan.funding_created(msg, best_block, &self.signer_provider, &self.logger) {
                                                Ok(res) => res,
                                                Err((mut inbound_chan, err)) => {
                                                        // We've already removed this inbound channel from the map in `PeerState`
                                                        // above so at this point we just need to clean up any lingering entries
                                                        // concerning this channel as it is safe to do so.
                                                        update_maps_on_chan_removal!(self, &inbound_chan.context);
                                                        let user_id = inbound_chan.context.get_user_id();
                                                        let shutdown_res = inbound_chan.context.force_shutdown(false);
                                                        return Err(MsgHandleErrInternal::from_finish_shutdown(format!("{}", err),
                                                                msg.temporary_channel_id, user_id, shutdown_res, None, inbound_chan.context.get_value_satoshis()));
                                                },
                                        }
                                },
                                Some(ChannelPhase::Funded(_)) | Some(ChannelPhase::UnfundedOutboundV1(_)) => {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got an unexpected funding_created message from peer with counterparty_node_id {}", counterparty_node_id), msg.temporary_channel_id));
                                },
                                None => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.temporary_channel_id))
                        };

                match peer_state.channel_by_id.entry(chan.context.channel_id()) {
                        hash_map::Entry::Occupied(_) => {
                                Err(MsgHandleErrInternal::send_err_msg_no_close(
                                        "Already had channel with the new channel_id".to_owned(),
                                        chan.context.channel_id()
                                ))
                        },
                        hash_map::Entry::Vacant(e) => {
                                let mut id_to_peer_lock = self.id_to_peer.lock().unwrap();
                                match id_to_peer_lock.entry(chan.context.channel_id()) {
                                        hash_map::Entry::Occupied(_) => {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close(
                                                        "The funding_created message had the same funding_txid as an existing channel - funding is not possible".to_owned(),
                                                        chan.context.channel_id()))
                                        },
                                        hash_map::Entry::Vacant(i_e) => {
                                                let monitor_res = self.chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
                                                if let Ok(persist_state) = monitor_res {
                                                        i_e.insert(chan.context.get_counterparty_node_id());
                                                        mem::drop(id_to_peer_lock);

                                                        // There's no problem signing a counterparty's funding transaction if our monitor
                                                        // hasn't persisted to disk yet - we can't lose money on a transaction that we haven't
                                                        // accepted payment from yet. We do, however, need to wait to send our channel_ready
                                                        // until we have persisted our monitor.
                                                        if let Some(msg) = funding_msg_opt {
                                                                peer_state.pending_msg_events.push(events::MessageSendEvent::SendFundingSigned {
                                                                        node_id: counterparty_node_id.clone(),
                                                                        msg,
                                                                });
                                                        }

                                                        if let ChannelPhase::Funded(chan) = e.insert(ChannelPhase::Funded(chan)) {
                                                                handle_new_monitor_update!(self, persist_state, peer_state_lock, peer_state,
                                                                        per_peer_state, chan, INITIAL_MONITOR);
                                                        } else {
                                                                unreachable!("This must be a funded channel as we just inserted it.");
                                                        }
                                                        Ok(())
                                                } else {
                                                        log_error!(self.logger, "Persisting initial ChannelMonitor failed, implying the funding outpoint was duplicated");
                                                        let channel_id = match funding_msg_opt {
                                                                Some(msg) => msg.channel_id,
                                                                None => chan.context.channel_id(),
                                                        };
                                                        return Err(MsgHandleErrInternal::send_err_msg_no_close(
                                                                "The funding_created message had the same funding_txid as an existing channel - funding is not possible".to_owned(),
                                                                channel_id));
                                                }
                                        }
                                }
                        }
                }
        }

        fn internal_funding_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingSigned) -> Result<(), MsgHandleErrInternal> {
                let best_block = *self.best_block.read().unwrap();
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;

                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                match chan_phase_entry.get_mut() {
                                        ChannelPhase::Funded(ref mut chan) => {
                                                let monitor = try_chan_phase_entry!(self,
                                                        chan.funding_signed(&msg, best_block, &self.signer_provider, &self.logger), chan_phase_entry);
                                                if let Ok(persist_status) = self.chain_monitor.watch_channel(chan.context.get_funding_txo().unwrap(), monitor) {
                                                        handle_new_monitor_update!(self, persist_status, peer_state_lock, peer_state, per_peer_state, chan, INITIAL_MONITOR);
                                                        Ok(())
                                                } else {
                                                        try_chan_phase_entry!(self, Err(ChannelError::Close("Channel funding outpoint was a duplicate".to_owned())), chan_phase_entry)
                                                }
                                        },
                                        _ => {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id));
                                        },
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
        }

        fn internal_channel_ready(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReady) -> Result<(), MsgHandleErrInternal> {
                // Note that the ChannelManager is NOT re-persisted on disk after this (unless we error
                // closing a channel), so any changes are likely to be lost on restart!
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        let announcement_sigs_opt = try_chan_phase_entry!(self, chan.channel_ready(&msg, &self.node_signer,
                                                self.chain_hash, &self.default_configuration, &self.best_block.read().unwrap(), &self.logger), chan_phase_entry);
                                        if let Some(announcement_sigs) = announcement_sigs_opt {
                                                log_trace!(self.logger, "Sending announcement_signatures for channel {}", chan.context.channel_id());
                                                peer_state.pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                        node_id: counterparty_node_id.clone(),
                                                        msg: announcement_sigs,
                                                });
                                        } else if chan.context.is_usable() {
                                                // If we're sending an announcement_signatures, we'll send the (public)
                                                // channel_update after sending a channel_announcement when we receive our
                                                // counterparty's announcement_signatures. Thus, we only bother to send a
                                                // channel_update here if the channel is not public, i.e. we're not sending an
                                                // announcement_signatures.
                                                log_trace!(self.logger, "Sending private initial channel_update for our counterparty on channel {}", chan.context.channel_id());
                                                if let Ok(msg) = self.get_channel_update_for_unicast(chan) {
                                                        peer_state.pending_msg_events.push(events::MessageSendEvent::SendChannelUpdate {
                                                                node_id: counterparty_node_id.clone(),
                                                                msg,
                                                        });
                                                }
                                        }

                                        {
                                                let mut pending_events = self.pending_events.lock().unwrap();
                                                emit_channel_ready_event!(pending_events, chan);
                                        }

                                        Ok(())
                                } else {
                                        try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got a channel_ready message for an unfunded channel!".into())), chan_phase_entry)
                                }
                        },
                        hash_map::Entry::Vacant(_) => {
                                Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                        }
                }
        }

        fn internal_shutdown(&self, counterparty_node_id: &PublicKey, msg: &msgs::Shutdown) -> Result<(), MsgHandleErrInternal> {
                let mut dropped_htlcs: Vec<(HTLCSource, PaymentHash)> = Vec::new();
                let mut finish_shutdown = None;
                {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                                .ok_or_else(|| {
                                        debug_assert!(false);
                                        MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                                })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        if let hash_map::Entry::Occupied(mut chan_phase_entry) = peer_state.channel_by_id.entry(msg.channel_id.clone()) {
                                let phase = chan_phase_entry.get_mut();
                                match phase {
                                        ChannelPhase::Funded(chan) => {
                                                if !chan.received_shutdown() {
                                                        log_info!(self.logger, "Received a shutdown message from our counterparty for channel {}{}.",
                                                                msg.channel_id,
                                                                if chan.sent_shutdown() { " after we initiated shutdown" } else { "" });
                                                }

                                                let funding_txo_opt = chan.context.get_funding_txo();
                                                let (shutdown, monitor_update_opt, htlcs) = try_chan_phase_entry!(self,
                                                        chan.shutdown(&self.signer_provider, &peer_state.latest_features, &msg), chan_phase_entry);
                                                dropped_htlcs = htlcs;

                                                if let Some(msg) = shutdown {
                                                        // We can send the `shutdown` message before updating the `ChannelMonitor`
                                                        // here as we don't need the monitor update to complete until we send a
                                                        // `shutdown_signed`, which we'll delay if we're pending a monitor update.
                                                        peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                                node_id: *counterparty_node_id,
                                                                msg,
                                                        });
                                                }
                                                // Update the monitor with the shutdown script if necessary.
                                                if let Some(monitor_update) = monitor_update_opt {
                                                        handle_new_monitor_update!(self, funding_txo_opt.unwrap(), monitor_update,
                                                                peer_state_lock, peer_state, per_peer_state, chan);
                                                }
                                        },
                                        ChannelPhase::UnfundedInboundV1(_) | ChannelPhase::UnfundedOutboundV1(_) => {
                                                let context = phase.context_mut();
                                                log_error!(self.logger, "Immediately closing unfunded channel {} as peer asked to cooperatively shut it down (which is unnecessary)", &msg.channel_id);
                                                self.issue_channel_close_events(&context, ClosureReason::CounterpartyCoopClosedUnfundedChannel);
                                                let mut chan = remove_channel_phase!(self, chan_phase_entry);
                                                finish_shutdown = Some(chan.context_mut().force_shutdown(false));
                                        },
                                }
                        } else {
                                return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                        }
                }
                for htlc_source in dropped_htlcs.drain(..) {
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id.clone()), channel_id: msg.channel_id };
                        let reason = HTLCFailReason::from_failure_code(0x4000 | 8);
                        self.fail_htlc_backwards_internal(&htlc_source.0, &htlc_source.1, &reason, receiver);
                }
                if let Some(shutdown_res) = finish_shutdown {
                        self.finish_close_channel(shutdown_res);
                }

                Ok(())
        }

        fn internal_closing_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::ClosingSigned) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let (tx, chan_option, shutdown_result) = {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                        if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                                let (closing_signed, tx, shutdown_result) = try_chan_phase_entry!(self, chan.closing_signed(&self.fee_estimator, &msg), chan_phase_entry);
                                                debug_assert_eq!(shutdown_result.is_some(), chan.is_shutdown());
                                                if let Some(msg) = closing_signed {
                                                        peer_state.pending_msg_events.push(events::MessageSendEvent::SendClosingSigned {
                                                                node_id: counterparty_node_id.clone(),
                                                                msg,
                                                        });
                                                }
                                                if tx.is_some() {
                                                        // We're done with this channel, we've got a signed closing transaction and
                                                        // will send the closing_signed back to the remote peer upon return. This
                                                        // also implies there are no pending HTLCs left on the channel, so we can
                                                        // fully delete it from tracking (the channel monitor is still around to
                                                        // watch for old state broadcasts)!
                                                        (tx, Some(remove_channel_phase!(self, chan_phase_entry)), shutdown_result)
                                                } else { (tx, None, shutdown_result) }
                                        } else {
                                                return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                        "Got a closing_signed message for an unfunded channel!".into())), chan_phase_entry);
                                        }
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                        }
                };
                if let Some(broadcast_tx) = tx {
                        log_info!(self.logger, "Broadcasting {}", log_tx!(broadcast_tx));
                        self.tx_broadcaster.broadcast_transactions(&[&broadcast_tx]);
                }
                if let Some(ChannelPhase::Funded(chan)) = chan_option {
                        if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                        msg: update
                                });
                        }
                        self.issue_channel_close_events(&chan.context, ClosureReason::CooperativeClosure);
                }
                mem::drop(per_peer_state);
                if let Some(shutdown_result) = shutdown_result {
                        self.finish_close_channel(shutdown_result);
                }
                Ok(())
        }

        fn internal_update_add_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateAddHTLC) -> Result<(), MsgHandleErrInternal> {
                //TODO: BOLT 4 points out a specific attack where a peer may re-send an onion packet and
                //determine the state of the payment based on our response/if we forward anything/the time
                //we take to respond. We should take care to avoid allowing such an attack.
                //
                //TODO: There exists a further attack where a node may garble the onion data, forward it to
                //us repeatedly garbled in different ways, and compare our error messages, which are
                //encrypted with the same key. It's not immediately obvious how to usefully exploit that,
                //but we should prevent it anyway.

                // Note that the ChannelManager is NOT re-persisted on disk after this (unless we error
                // closing a channel), so any changes are likely to be lost on restart!

                let decoded_hop_res = self.decode_update_add_htlc_onion(msg);
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        let pending_forward_info = match decoded_hop_res {
                                                Ok((next_hop, shared_secret, next_packet_pk_opt)) =>
                                                        self.construct_pending_htlc_status(msg, shared_secret, next_hop,
                                                                chan.context.config().accept_underpaying_htlcs, next_packet_pk_opt),
                                                Err(e) => PendingHTLCStatus::Fail(e)
                                        };
                                        let create_pending_htlc_status = |chan: &Channel<SP>, pending_forward_info: PendingHTLCStatus, error_code: u16| {
                                                // If the update_add is completely bogus, the call will Err and we will close,
                                                // but if we've sent a shutdown and they haven't acknowledged it yet, we just
                                                // want to reject the new HTLC and fail it backwards instead of forwarding.
                                                match pending_forward_info {
                                                        PendingHTLCStatus::Forward(PendingHTLCInfo { ref incoming_shared_secret, .. }) => {
                                                                let reason = if (error_code & 0x1000) != 0 {
                                                                        let (real_code, error_data) = self.get_htlc_inbound_temp_fail_err_and_data(error_code, chan);
                                                                        HTLCFailReason::reason(real_code, error_data)
                                                                } else {
                                                                        HTLCFailReason::from_failure_code(error_code)
                                                                }.get_encrypted_failure_packet(incoming_shared_secret, &None);
                                                                let msg = msgs::UpdateFailHTLC {
                                                                        channel_id: msg.channel_id,
                                                                        htlc_id: msg.htlc_id,
                                                                        reason
                                                                };
                                                                PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msg))
                                                        },
                                                        _ => pending_forward_info
                                                }
                                        };
                                        try_chan_phase_entry!(self, chan.update_add_htlc(&msg, pending_forward_info, create_pending_htlc_status, &self.fee_estimator, &self.logger), chan_phase_entry);
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got an update_add_htlc message for an unfunded channel!".into())), chan_phase_entry);
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                }
                Ok(())
        }

        fn internal_update_fulfill_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) -> Result<(), MsgHandleErrInternal> {
                let funding_txo;
                let (htlc_source, forwarded_htlc_value) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                                .ok_or_else(|| {
                                        debug_assert!(false);
                                        MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                                })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                        if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                                let res = try_chan_phase_entry!(self, chan.update_fulfill_htlc(&msg), chan_phase_entry);
                                                if let HTLCSource::PreviousHopData(prev_hop) = &res.0 {
                                                        log_trace!(self.logger,
                                                                "Holding the next revoke_and_ack from {} until the preimage is durably persisted in the inbound edge's ChannelMonitor",
                                                                msg.channel_id);
                                                        peer_state.actions_blocking_raa_monitor_updates.entry(msg.channel_id)
                                                                .or_insert_with(Vec::new)
                                                                .push(RAAMonitorUpdateBlockingAction::from_prev_hop_data(&prev_hop));
                                                }
                                                // Note that we do not need to push an `actions_blocking_raa_monitor_updates`
                                                // entry here, even though we *do* need to block the next RAA monitor update.
                                                // We do this instead in the `claim_funds_internal` by attaching a
                                                // `ReleaseRAAChannelMonitorUpdate` action to the event generated when the
                                                // outbound HTLC is claimed. This is guaranteed to all complete before we
                                                // process the RAA as messages are processed from single peers serially.
                                                funding_txo = chan.context.get_funding_txo().expect("We won't accept a fulfill until funded");
                                                res
                                        } else {
                                                return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                        "Got an update_fulfill_htlc message for an unfunded channel!".into())), chan_phase_entry);
                                        }
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                        }
                };
                self.claim_funds_internal(htlc_source, msg.payment_preimage.clone(), Some(forwarded_htlc_value), false, false, Some(*counterparty_node_id), funding_txo);
                Ok(())
        }

        fn internal_update_fail_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) -> Result<(), MsgHandleErrInternal> {
                // Note that the ChannelManager is NOT re-persisted on disk after this (unless we error
                // closing a channel), so any changes are likely to be lost on restart!
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        try_chan_phase_entry!(self, chan.update_fail_htlc(&msg, HTLCFailReason::from_msg(msg)), chan_phase_entry);
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got an update_fail_htlc message for an unfunded channel!".into())), chan_phase_entry);
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                }
                Ok(())
        }

        fn internal_update_fail_malformed_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) -> Result<(), MsgHandleErrInternal> {
                // Note that the ChannelManager is NOT re-persisted on disk after this (unless we error
                // closing a channel), so any changes are likely to be lost on restart!
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if (msg.failure_code & 0x8000) == 0 {
                                        let chan_err: ChannelError = ChannelError::Close("Got update_fail_malformed_htlc with BADONION not set".to_owned());
                                        try_chan_phase_entry!(self, Err(chan_err), chan_phase_entry);
                                }
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        try_chan_phase_entry!(self, chan.update_fail_malformed_htlc(&msg, HTLCFailReason::reason(msg.failure_code, msg.sha256_of_onion.to_vec())), chan_phase_entry);
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got an update_fail_malformed_htlc message for an unfunded channel!".into())), chan_phase_entry);
                                }
                                Ok(())
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                }
        }

        fn internal_commitment_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::CommitmentSigned) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        let funding_txo = chan.context.get_funding_txo();
                                        let monitor_update_opt = try_chan_phase_entry!(self, chan.commitment_signed(&msg, &self.logger), chan_phase_entry);
                                        if let Some(monitor_update) = monitor_update_opt {
                                                handle_new_monitor_update!(self, funding_txo.unwrap(), monitor_update, peer_state_lock,
                                                        peer_state, per_peer_state, chan);
                                        }
                                        Ok(())
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got a commitment_signed message for an unfunded channel!".into())), chan_phase_entry);
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                }
        }

        #[inline]
        fn forward_htlcs(&self, per_source_pending_forwards: &mut [(u64, OutPoint, u128, Vec<(PendingHTLCInfo, u64)>)]) {
                for &mut (prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, ref mut pending_forwards) in per_source_pending_forwards {
                        let mut push_forward_event = false;
                        let mut new_intercept_events = VecDeque::new();
                        let mut failed_intercept_forwards = Vec::new();
                        if !pending_forwards.is_empty() {
                                for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
                                        let scid = match forward_info.routing {
                                                PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
                                                PendingHTLCRouting::Receive { .. } => 0,
                                                PendingHTLCRouting::ReceiveKeysend { .. } => 0,
                                        };
                                        // Pull this now to avoid introducing a lock order with `forward_htlcs`.
                                        let is_our_scid = self.short_to_chan_info.read().unwrap().contains_key(&scid);

                                        let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
                                        let forward_htlcs_empty = forward_htlcs.is_empty();
                                        match forward_htlcs.entry(scid) {
                                                hash_map::Entry::Occupied(mut entry) => {
                                                        entry.get_mut().push(HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info }));
                                                },
                                                hash_map::Entry::Vacant(entry) => {
                                                        if !is_our_scid && forward_info.incoming_amt_msat.is_some() &&
                                                           fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, scid, &self.chain_hash)
                                                        {
                                                                let intercept_id = InterceptId(Sha256::hash(&forward_info.incoming_shared_secret).to_byte_array());
                                                                let mut pending_intercepts = self.pending_intercepted_htlcs.lock().unwrap();
                                                                match pending_intercepts.entry(intercept_id) {
                                                                        hash_map::Entry::Vacant(entry) => {
                                                                                new_intercept_events.push_back((events::Event::HTLCIntercepted {
                                                                                        requested_next_hop_scid: scid,
                                                                                        payment_hash: forward_info.payment_hash,
                                                                                        inbound_amount_msat: forward_info.incoming_amt_msat.unwrap(),
                                                                                        expected_outbound_amount_msat: forward_info.outgoing_amt_msat,
                                                                                        intercept_id
                                                                                }, None));
                                                                                entry.insert(PendingAddHTLCInfo {
                                                                                        prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info });
                                                                        },
                                                                        hash_map::Entry::Occupied(_) => {
                                                                                log_info!(self.logger, "Failed to forward incoming HTLC: detected duplicate intercepted payment over short channel id {}", scid);
                                                                                let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                                                                        short_channel_id: prev_short_channel_id,
                                                                                        user_channel_id: Some(prev_user_channel_id),
                                                                                        outpoint: prev_funding_outpoint,
                                                                                        htlc_id: prev_htlc_id,
                                                                                        incoming_packet_shared_secret: forward_info.incoming_shared_secret,
                                                                                        phantom_shared_secret: None,
                                                                                });

                                                                                failed_intercept_forwards.push((htlc_source, forward_info.payment_hash,
                                                                                                HTLCFailReason::from_failure_code(0x4000 | 10),
                                                                                                HTLCDestination::InvalidForward { requested_forward_scid: scid },
                                                                                ));
                                                                        }
                                                                }
                                                        } else {
                                                                // We don't want to generate a PendingHTLCsForwardable event if only intercepted
                                                                // payments are being processed.
                                                                if forward_htlcs_empty {
                                                                        push_forward_event = true;
                                                                }
                                                                entry.insert(vec!(HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                        prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info })));
                                                        }
                                                }
                                        }
                                }
                        }

                        for (htlc_source, payment_hash, failure_reason, destination) in failed_intercept_forwards.drain(..) {
                                self.fail_htlc_backwards_internal(&htlc_source, &payment_hash, &failure_reason, destination);
                        }

                        if !new_intercept_events.is_empty() {
                                let mut events = self.pending_events.lock().unwrap();
                                events.append(&mut new_intercept_events);
                        }
                        if push_forward_event { self.push_pending_forwards_ev() }
                }
        }

        fn push_pending_forwards_ev(&self) {
                let mut pending_events = self.pending_events.lock().unwrap();
                let is_processing_events = self.pending_events_processor.load(Ordering::Acquire);
                let num_forward_events = pending_events.iter().filter(|(ev, _)|
                        if let events::Event::PendingHTLCsForwardable { .. } = ev { true } else { false }
                ).count();
                // We only want to push a PendingHTLCsForwardable event if no others are queued. Processing
                // events is done in batches and they are not removed until we're done processing each
                // batch. Since handling a `PendingHTLCsForwardable` event will call back into the
                // `ChannelManager`, we'll still see the original forwarding event not removed. Phantom
                // payments will need an additional forwarding event before being claimed to make them look
                // real by taking more time.
                if (is_processing_events && num_forward_events <= 1) || num_forward_events < 1 {
                        pending_events.push_back((Event::PendingHTLCsForwardable {
                                time_forwardable: Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS),
                        }, None));
                }
        }

        /// Checks whether [`ChannelMonitorUpdate`]s generated by the receipt of a remote
        /// [`msgs::RevokeAndACK`] should be held for the given channel until some other action
        /// completes. Note that this needs to happen in the same [`PeerState`] mutex as any release of
        /// the [`ChannelMonitorUpdate`] in question.
        fn raa_monitor_updates_held(&self,
                actions_blocking_raa_monitor_updates: &BTreeMap<ChannelId, Vec<RAAMonitorUpdateBlockingAction>>,
                channel_funding_outpoint: OutPoint, counterparty_node_id: PublicKey
        ) -> bool {
                actions_blocking_raa_monitor_updates
                        .get(&channel_funding_outpoint.to_channel_id()).map(|v| !v.is_empty()).unwrap_or(false)
                || self.pending_events.lock().unwrap().iter().any(|(_, action)| {
                        action == &Some(EventCompletionAction::ReleaseRAAChannelMonitorUpdate {
                                channel_funding_outpoint,
                                counterparty_node_id,
                        })
                })
        }

        #[cfg(any(test, feature = "_test_utils"))]
        pub(crate) fn test_raa_monitor_updates_held(&self,
                counterparty_node_id: PublicKey, channel_id: ChannelId
        ) -> bool {
                let per_peer_state = self.per_peer_state.read().unwrap();
                if let Some(peer_state_mtx) = per_peer_state.get(&counterparty_node_id) {
                        let mut peer_state_lck = peer_state_mtx.lock().unwrap();
                        let peer_state = &mut *peer_state_lck;

                        if let Some(chan) = peer_state.channel_by_id.get(&channel_id) {
                                return self.raa_monitor_updates_held(&peer_state.actions_blocking_raa_monitor_updates,
                                        chan.context().get_funding_txo().unwrap(), counterparty_node_id);
                        }
                }
                false
        }

        fn internal_revoke_and_ack(&self, counterparty_node_id: &PublicKey, msg: &msgs::RevokeAndACK) -> Result<(), MsgHandleErrInternal> {
                let htlcs_to_fail = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let mut peer_state_lock = per_peer_state.get(counterparty_node_id)
                                .ok_or_else(|| {
                                        debug_assert!(false);
                                        MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                                }).map(|mtx| mtx.lock().unwrap())?;
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                        if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                                let funding_txo_opt = chan.context.get_funding_txo();
                                                let mon_update_blocked = if let Some(funding_txo) = funding_txo_opt {
                                                        self.raa_monitor_updates_held(
                                                                &peer_state.actions_blocking_raa_monitor_updates, funding_txo,
                                                                *counterparty_node_id)
                                                } else { false };
                                                let (htlcs_to_fail, monitor_update_opt) = try_chan_phase_entry!(self,
                                                        chan.revoke_and_ack(&msg, &self.fee_estimator, &self.logger, mon_update_blocked), chan_phase_entry);
                                                if let Some(monitor_update) = monitor_update_opt {
                                                        let funding_txo = funding_txo_opt
                                                                .expect("Funding outpoint must have been set for RAA handling to succeed");
                                                        handle_new_monitor_update!(self, funding_txo, monitor_update,
                                                                peer_state_lock, peer_state, per_peer_state, chan);
                                                }
                                                htlcs_to_fail
                                        } else {
                                                return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                        "Got a revoke_and_ack message for an unfunded channel!".into())), chan_phase_entry);
                                        }
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                        }
                };
                self.fail_holding_cell_htlcs(htlcs_to_fail, msg.channel_id, counterparty_node_id);
                Ok(())
        }

        fn internal_update_fee(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFee) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        try_chan_phase_entry!(self, chan.update_fee(&self.fee_estimator, &msg, &self.logger), chan_phase_entry);
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got an update_fee message for an unfunded channel!".into())), chan_phase_entry);
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                }
                Ok(())
        }

        fn internal_announcement_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                        .ok_or_else(|| {
                                debug_assert!(false);
                                MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
                        })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        if !chan.context.is_usable() {
                                                return Err(MsgHandleErrInternal::from_no_close(LightningError{err: "Got an announcement_signatures before we were ready for it".to_owned(), action: msgs::ErrorAction::IgnoreError}));
                                        }

                                        peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelAnnouncement {
                                                msg: try_chan_phase_entry!(self, chan.announcement_signatures(
                                                        &self.node_signer, self.chain_hash, self.best_block.read().unwrap().height(),
                                                        msg, &self.default_configuration
                                                ), chan_phase_entry),
                                                // Note that announcement_signatures fails if the channel cannot be announced,
                                                // so get_channel_update_for_broadcast will never fail by the time we get here.
                                                update_msg: Some(self.get_channel_update_for_broadcast(chan).unwrap()),
                                        });
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got an announcement_signatures message for an unfunded channel!".into())), chan_phase_entry);
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
                }
                Ok(())
        }

        /// Returns DoPersist if anything changed, otherwise either SkipPersistNoEvents or an Err.
        fn internal_channel_update(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelUpdate) -> Result<NotifyOption, MsgHandleErrInternal> {
                let (chan_counterparty_node_id, chan_id) = match self.short_to_chan_info.read().unwrap().get(&msg.contents.short_channel_id) {
                        Some((cp_id, chan_id)) => (cp_id.clone(), chan_id.clone()),
                        None => {
                                // It's not a local channel
                                return Ok(NotifyOption::SkipPersistNoEvents)
                        }
                };
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex_opt = per_peer_state.get(&chan_counterparty_node_id);
                if peer_state_mutex_opt.is_none() {
                        return Ok(NotifyOption::SkipPersistNoEvents)
                }
                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(chan_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                        if chan.context.get_counterparty_node_id() != *counterparty_node_id {
                                                if chan.context.should_announce() {
                                                        // If the announcement is about a channel of ours which is public, some
                                                        // other peer may simply be forwarding all its gossip to us. Don't provide
                                                        // a scary-looking error message and return Ok instead.
                                                        return Ok(NotifyOption::SkipPersistNoEvents);
                                                }
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a channel_update for a channel from the wrong node - it shouldn't know about our private channels!".to_owned(), chan_id));
                                        }
                                        let were_node_one = self.get_our_node_id().serialize()[..] < chan.context.get_counterparty_node_id().serialize()[..];
                                        let msg_from_node_one = msg.contents.flags & 1 == 0;
                                        if were_node_one == msg_from_node_one {
                                                return Ok(NotifyOption::SkipPersistNoEvents);
                                        } else {
                                                log_debug!(self.logger, "Received channel_update {:?} for channel {}.", msg, chan_id);
                                                let did_change = try_chan_phase_entry!(self, chan.channel_update(&msg), chan_phase_entry);
                                                // If nothing changed after applying their update, we don't need to bother
                                                // persisting.
                                                if !did_change {
                                                        return Ok(NotifyOption::SkipPersistNoEvents);
                                                }
                                        }
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got a channel_update for an unfunded channel!".into())), chan_phase_entry);
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Ok(NotifyOption::SkipPersistNoEvents)
                }
                Ok(NotifyOption::DoPersist)
        }

        fn internal_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) -> Result<NotifyOption, MsgHandleErrInternal> {
                let htlc_forwards;
                let need_lnd_workaround = {
                        let per_peer_state = self.per_peer_state.read().unwrap();

                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
                                .ok_or_else(|| {
                                        debug_assert!(false);
                                        MsgHandleErrInternal::send_err_msg_no_close(
                                                format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id),
                                                msg.channel_id
                                        )
                                })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                        if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                                // Currently, we expect all holding cell update_adds to be dropped on peer
                                                // disconnect, so Channel's reestablish will never hand us any holding cell
                                                // freed HTLCs to fail backwards. If in the future we no longer drop pending
                                                // add-HTLCs on disconnect, we may be handed HTLCs to fail backwards here.
                                                let responses = try_chan_phase_entry!(self, chan.channel_reestablish(
                                                        msg, &self.logger, &self.node_signer, self.chain_hash,
                                                        &self.default_configuration, &*self.best_block.read().unwrap()), chan_phase_entry);
                                                let mut channel_update = None;
                                                if let Some(msg) = responses.shutdown_msg {
                                                        peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                                node_id: counterparty_node_id.clone(),
                                                                msg,
                                                        });
                                                } else if chan.context.is_usable() {
                                                        // If the channel is in a usable state (ie the channel is not being shut
                                                        // down), send a unicast channel_update to our counterparty to make sure
                                                        // they have the latest channel parameters.
                                                        if let Ok(msg) = self.get_channel_update_for_unicast(chan) {
                                                                channel_update = Some(events::MessageSendEvent::SendChannelUpdate {
                                                                        node_id: chan.context.get_counterparty_node_id(),
                                                                        msg,
                                                                });
                                                        }
                                                }
                                                let need_lnd_workaround = chan.context.workaround_lnd_bug_4006.take();
                                                htlc_forwards = self.handle_channel_resumption(
                                                        &mut peer_state.pending_msg_events, chan, responses.raa, responses.commitment_update, responses.order,
                                                        Vec::new(), None, responses.channel_ready, responses.announcement_sigs);
                                                if let Some(upd) = channel_update {
                                                        peer_state.pending_msg_events.push(upd);
                                                }
                                                need_lnd_workaround
                                        } else {
                                                return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                        "Got a channel_reestablish message for an unfunded channel!".into())), chan_phase_entry);
                                        }
                                },
                                hash_map::Entry::Vacant(_) => {
                                        log_debug!(self.logger, "Sending bogus ChannelReestablish for unknown channel {} to force channel closure",
                                                log_bytes!(msg.channel_id.0));
                                        // Unfortunately, lnd doesn't force close on errors
                                        // (https://github.com/lightningnetwork/lnd/blob/abb1e3463f3a83bbb843d5c399869dbe930ad94f/htlcswitch/link.go#L2119).
                                        // One of the few ways to get an lnd counterparty to force close is by
                                        // replicating what they do when restoring static channel backups (SCBs). They
                                        // send an invalid `ChannelReestablish` with `0` commitment numbers and an
                                        // invalid `your_last_per_commitment_secret`.
                                        //
                                        // Since we received a `ChannelReestablish` for a channel that doesn't exist, we
                                        // can assume it's likely the channel closed from our point of view, but it
                                        // remains open on the counterparty's side. By sending this bogus
                                        // `ChannelReestablish` message now as a response to theirs, we trigger them to
                                        // force close broadcasting their latest state. If the closing transaction from
                                        // our point of view remains unconfirmed, it'll enter a race with the
                                        // counterparty's to-be-broadcast latest commitment transaction.
                                        peer_state.pending_msg_events.push(MessageSendEvent::SendChannelReestablish {
                                                node_id: *counterparty_node_id,
                                                msg: msgs::ChannelReestablish {
                                                        channel_id: msg.channel_id,
                                                        next_local_commitment_number: 0,
                                                        next_remote_commitment_number: 0,
                                                        your_last_per_commitment_secret: [1u8; 32],
                                                        my_current_per_commitment_point: PublicKey::from_slice(&[2u8; 33]).unwrap(),
                                                        next_funding_txid: None,
                                                },
                                        });
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close(
                                                format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}",
                                                        counterparty_node_id), msg.channel_id)
                                        )
                                }
                        }
                };

                let mut persist = NotifyOption::SkipPersistHandleEvents;
                if let Some(forwards) = htlc_forwards {
                        self.forward_htlcs(&mut [forwards][..]);
                        persist = NotifyOption::DoPersist;
                }

                if let Some(channel_ready_msg) = need_lnd_workaround {
                        self.internal_channel_ready(counterparty_node_id, &channel_ready_msg)?;
                }
                Ok(persist)
        }

        /// Process pending events from the [`chain::Watch`], returning whether any events were processed.
        fn process_pending_monitor_events(&self) -> bool {
                debug_assert!(self.total_consistency_lock.try_write().is_err()); // Caller holds read lock

                let mut failed_channels = Vec::new();
                let mut pending_monitor_events = self.chain_monitor.release_pending_monitor_events();
                let has_pending_monitor_events = !pending_monitor_events.is_empty();
                for (funding_outpoint, mut monitor_events, counterparty_node_id) in pending_monitor_events.drain(..) {
                        for monitor_event in monitor_events.drain(..) {
                                match monitor_event {
                                        MonitorEvent::HTLCEvent(htlc_update) => {
                                                if let Some(preimage) = htlc_update.payment_preimage {
                                                        log_trace!(self.logger, "Claiming HTLC with preimage {} from our monitor", preimage);
                                                        self.claim_funds_internal(htlc_update.source, preimage, htlc_update.htlc_value_satoshis.map(|v| v * 1000), true, false, counterparty_node_id, funding_outpoint);
                                                } else {
                                                        log_trace!(self.logger, "Failing HTLC with hash {} from our monitor", &htlc_update.payment_hash);
                                                        let receiver = HTLCDestination::NextHopChannel { node_id: counterparty_node_id, channel_id: funding_outpoint.to_channel_id() };
                                                        let reason = HTLCFailReason::from_failure_code(0x4000 | 8);
                                                        self.fail_htlc_backwards_internal(&htlc_update.source, &htlc_update.payment_hash, &reason, receiver);
                                                }
                                        },
                                        MonitorEvent::HolderForceClosed(funding_outpoint) => {
                                                let counterparty_node_id_opt = match counterparty_node_id {
                                                        Some(cp_id) => Some(cp_id),
                                                        None => {
                                                                // TODO: Once we can rely on the counterparty_node_id from the
                                                                // monitor event, this and the id_to_peer map should be removed.
                                                                let id_to_peer = self.id_to_peer.lock().unwrap();
                                                                id_to_peer.get(&funding_outpoint.to_channel_id()).cloned()
                                                        }
                                                };
                                                if let Some(counterparty_node_id) = counterparty_node_id_opt {
                                                        let per_peer_state = self.per_peer_state.read().unwrap();
                                                        if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
                                                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                                                let peer_state = &mut *peer_state_lock;
                                                                let pending_msg_events = &mut peer_state.pending_msg_events;
                                                                if let hash_map::Entry::Occupied(chan_phase_entry) = peer_state.channel_by_id.entry(funding_outpoint.to_channel_id()) {
                                                                        if let ChannelPhase::Funded(mut chan) = remove_channel_phase!(self, chan_phase_entry) {
                                                                                failed_channels.push(chan.context.force_shutdown(false));
                                                                                if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                                msg: update
                                                                                        });
                                                                                }
                                                                                self.issue_channel_close_events(&chan.context, ClosureReason::HolderForceClosed);
                                                                                pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                                                        node_id: chan.context.get_counterparty_node_id(),
                                                                                        action: msgs::ErrorAction::DisconnectPeer {
                                                                                                msg: Some(msgs::ErrorMessage { channel_id: chan.context.channel_id(), data: "Channel force-closed".to_owned() })
                                                                                        },
                                                                                });
                                                                        }
                                                                }
                                                        }
                                                }
                                        },
                                        MonitorEvent::Completed { funding_txo, monitor_update_id } => {
                                                self.channel_monitor_updated(&funding_txo, monitor_update_id, counterparty_node_id.as_ref());
                                        },
                                }
                        }
                }

                for failure in failed_channels.drain(..) {
                        self.finish_close_channel(failure);
                }

                has_pending_monitor_events
        }

        /// In chanmon_consistency_target, we'd like to be able to restore monitor updating without
        /// handling all pending events (i.e. not PendingHTLCsForwardable). Thus, we expose monitor
        /// update events as a separate process method here.
        #[cfg(fuzzing)]
        pub fn process_monitor_events(&self) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.process_pending_monitor_events();
        }

        /// Check the holding cell in each channel and free any pending HTLCs in them if possible.
        /// Returns whether there were any updates such as if pending HTLCs were freed or a monitor
        /// update was applied.
        fn check_free_holding_cells(&self) -> bool {
                let mut has_monitor_update = false;
                let mut failed_htlcs = Vec::new();

                // Walk our list of channels and find any that need to update. Note that when we do find an
                // update, if it includes actions that must be taken afterwards, we have to drop the
                // per-peer state lock as well as the top level per_peer_state lock. Thus, we loop until we
                // manage to go through all our peers without finding a single channel to update.
                'peer_loop: loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                'chan_loop: loop {
                                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                        let peer_state: &mut PeerState<_> = &mut *peer_state_lock;
                                        for (channel_id, chan) in peer_state.channel_by_id.iter_mut().filter_map(
                                                |(chan_id, phase)| if let ChannelPhase::Funded(chan) = phase { Some((chan_id, chan)) } else { None }
                                        ) {
                                                let counterparty_node_id = chan.context.get_counterparty_node_id();
                                                let funding_txo = chan.context.get_funding_txo();
                                                let (monitor_opt, holding_cell_failed_htlcs) =
                                                        chan.maybe_free_holding_cell_htlcs(&self.fee_estimator, &self.logger);
                                                if !holding_cell_failed_htlcs.is_empty() {
                                                        failed_htlcs.push((holding_cell_failed_htlcs, *channel_id, counterparty_node_id));
                                                }
                                                if let Some(monitor_update) = monitor_opt {
                                                        has_monitor_update = true;

                                                        handle_new_monitor_update!(self, funding_txo.unwrap(), monitor_update,
                                                                peer_state_lock, peer_state, per_peer_state, chan);
                                                        continue 'peer_loop;
                                                }
                                        }
                                        break 'chan_loop;
                                }
                        }
                        break 'peer_loop;
                }

                let has_update = has_monitor_update || !failed_htlcs.is_empty();
                for (failures, channel_id, counterparty_node_id) in failed_htlcs.drain(..) {
                        self.fail_holding_cell_htlcs(failures, channel_id, &counterparty_node_id);
                }

                has_update
        }

        /// When a call to a [`ChannelSigner`] method returns an error, this indicates that the signer
        /// is (temporarily) unavailable, and the operation should be retried later.
        ///
        /// This method allows for that retry - either checking for any signer-pending messages to be
        /// attempted in every channel, or in the specifically provided channel.
        ///
        /// [`ChannelSigner`]: crate::sign::ChannelSigner
        #[cfg(test)] // This is only implemented for one signer method, and should be private until we
                     // actually finish implementing it fully.
        pub fn signer_unblocked(&self, channel_opt: Option<(PublicKey, ChannelId)>) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                let unblock_chan = |phase: &mut ChannelPhase<SP>, pending_msg_events: &mut Vec<MessageSendEvent>| {
                        let node_id = phase.context().get_counterparty_node_id();
                        if let ChannelPhase::Funded(chan) = phase {
                                let msgs = chan.signer_maybe_unblocked(&self.logger);
                                if let Some(updates) = msgs.commitment_update {
                                        pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                node_id,
                                                updates,
                                        });
                                }
                                if let Some(msg) = msgs.funding_signed {
                                        pending_msg_events.push(events::MessageSendEvent::SendFundingSigned {
                                                node_id,
                                                msg,
                                        });
                                }
                                if let Some(msg) = msgs.funding_created {
                                        pending_msg_events.push(events::MessageSendEvent::SendFundingCreated {
                                                node_id,
                                                msg,
                                        });
                                }
                                if let Some(msg) = msgs.channel_ready {
                                        send_channel_ready!(self, pending_msg_events, chan, msg);
                                }
                        }
                };

                let per_peer_state = self.per_peer_state.read().unwrap();
                if let Some((counterparty_node_id, channel_id)) = channel_opt {
                        if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                if let Some(chan) = peer_state.channel_by_id.get_mut(&channel_id) {
                                        unblock_chan(chan, &mut peer_state.pending_msg_events);
                                }
                        }
                } else {
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                for (_, chan) in peer_state.channel_by_id.iter_mut() {
                                        unblock_chan(chan, &mut peer_state.pending_msg_events);
                                }
                        }
                }
        }

        /// Check whether any channels have finished removing all pending updates after a shutdown
        /// exchange and can now send a closing_signed.
        /// Returns whether any closing_signed messages were generated.
        fn maybe_generate_initial_closing_signed(&self) -> bool {
                let mut handle_errors: Vec<(PublicKey, Result<(), _>)> = Vec::new();
                let mut has_update = false;
                let mut shutdown_results = Vec::new();
                {
                        let per_peer_state = self.per_peer_state.read().unwrap();

                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                let pending_msg_events = &mut peer_state.pending_msg_events;
                                peer_state.channel_by_id.retain(|channel_id, phase| {
                                        match phase {
                                                ChannelPhase::Funded(chan) => {
                                                        match chan.maybe_propose_closing_signed(&self.fee_estimator, &self.logger) {
                                                                Ok((msg_opt, tx_opt, shutdown_result_opt)) => {
                                                                        if let Some(msg) = msg_opt {
                                                                                has_update = true;
                                                                                pending_msg_events.push(events::MessageSendEvent::SendClosingSigned {
                                                                                        node_id: chan.context.get_counterparty_node_id(), msg,
                                                                                });
                                                                        }
                                                                        debug_assert_eq!(shutdown_result_opt.is_some(), chan.is_shutdown());
                                                                        if let Some(shutdown_result) = shutdown_result_opt {
                                                                                shutdown_results.push(shutdown_result);
                                                                        }
                                                                        if let Some(tx) = tx_opt {
                                                                                // We're done with this channel. We got a closing_signed and sent back
                                                                                // a closing_signed with a closing transaction to broadcast.
                                                                                if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                                msg: update
                                                                                        });
                                                                                }

                                                                                self.issue_channel_close_events(&chan.context, ClosureReason::CooperativeClosure);

                                                                                log_info!(self.logger, "Broadcasting {}", log_tx!(tx));
                                                                                self.tx_broadcaster.broadcast_transactions(&[&tx]);
                                                                                update_maps_on_chan_removal!(self, &chan.context);
                                                                                false
                                                                        } else { true }
                                                                },
                                                                Err(e) => {
                                                                        has_update = true;
                                                                        let (close_channel, res) = convert_chan_phase_err!(self, e, chan, channel_id, FUNDED_CHANNEL);
                                                                        handle_errors.push((chan.context.get_counterparty_node_id(), Err(res)));
                                                                        !close_channel
                                                                }
                                                        }
                                                },
                                                _ => true, // Retain unfunded channels if present.
                                        }
                                });
                        }
                }

                for (counterparty_node_id, err) in handle_errors.drain(..) {
                        let _ = handle_error!(self, err, counterparty_node_id);
                }

                for shutdown_result in shutdown_results.drain(..) {
                        self.finish_close_channel(shutdown_result);
                }

                has_update
        }

        /// Handle a list of channel failures during a block_connected or block_disconnected call,
        /// pushing the channel monitor update (if any) to the background events queue and removing the
        /// Channel object.
        fn handle_init_event_channel_failures(&self, mut failed_channels: Vec<ShutdownResult>) {
                for mut failure in failed_channels.drain(..) {
                        // Either a commitment transactions has been confirmed on-chain or
                        // Channel::block_disconnected detected that the funding transaction has been
                        // reorganized out of the main chain.
                        // We cannot broadcast our latest local state via monitor update (as
                        // Channel::force_shutdown tries to make us do) as we may still be in initialization,
                        // so we track the update internally and handle it when the user next calls
                        // timer_tick_occurred, guaranteeing we're running normally.
                        if let Some((counterparty_node_id, funding_txo, update)) = failure.monitor_update.take() {
                                assert_eq!(update.updates.len(), 1);
                                if let ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast } = update.updates[0] {
                                        assert!(should_broadcast);
                                } else { unreachable!(); }
                                self.pending_background_events.lock().unwrap().push(
                                        BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
                                                counterparty_node_id, funding_txo, update
                                        });
                        }
                        self.finish_close_channel(failure);
                }
        }

        /// Creates an [`OfferBuilder`] such that the [`Offer`] it builds is recognized by the
        /// [`ChannelManager`] when handling [`InvoiceRequest`] messages for the offer. The offer will
        /// not have an expiration unless otherwise set on the builder.
        ///
        /// # Privacy
        ///
        /// Uses a one-hop [`BlindedPath`] for the offer with [`ChannelManager::get_our_node_id`] as the
        /// introduction node and a derived signing pubkey for recipient privacy. As such, currently,
        /// the node must be announced. Otherwise, there is no way to find a path to the introduction
        /// node in order to send the [`InvoiceRequest`].
        ///
        /// # Limitations
        ///
        /// Requires a direct connection to the introduction node in the responding [`InvoiceRequest`]'s
        /// reply path.
        ///
        /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
        ///
        /// [`Offer`]: crate::offers::offer::Offer
        /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
        pub fn create_offer_builder(
                &self, description: String
        ) -> OfferBuilder<DerivedMetadata, secp256k1::All> {
                let node_id = self.get_our_node_id();
                let expanded_key = &self.inbound_payment_key;
                let entropy = &*self.entropy_source;
                let secp_ctx = &self.secp_ctx;
                let path = self.create_one_hop_blinded_path();

                OfferBuilder::deriving_signing_pubkey(description, node_id, expanded_key, entropy, secp_ctx)
                        .chain_hash(self.chain_hash)
                        .path(path)
        }

        /// Creates a [`RefundBuilder`] such that the [`Refund`] it builds is recognized by the
        /// [`ChannelManager`] when handling [`Bolt12Invoice`] messages for the refund.
        ///
        /// # Payment
        ///
        /// The provided `payment_id` is used to ensure that only one invoice is paid for the refund.
        /// See [Avoiding Duplicate Payments] for other requirements once the payment has been sent.
        ///
        /// The builder will have the provided expiration set. Any changes to the expiration on the
        /// returned builder will not be honored by [`ChannelManager`]. For `no-std`, the highest seen
        /// block time minus two hours is used for the current time when determining if the refund has
        /// expired.
        ///
        /// To revoke the refund, use [`ChannelManager::abandon_payment`] prior to receiving the
        /// invoice. If abandoned, or an invoice isn't received before expiration, the payment will fail
        /// with an [`Event::InvoiceRequestFailed`].
        ///
        /// If `max_total_routing_fee_msat` is not specified, The default from
        /// [`RouteParameters::from_payment_params_and_value`] is applied.
        ///
        /// # Privacy
        ///
        /// Uses a one-hop [`BlindedPath`] for the refund with [`ChannelManager::get_our_node_id`] as
        /// the introduction node and a derived payer id for payer privacy. As such, currently, the
        /// node must be announced. Otherwise, there is no way to find a path to the introduction node
        /// in order to send the [`Bolt12Invoice`].
        ///
        /// # Limitations
        ///
        /// Requires a direct connection to an introduction node in the responding
        /// [`Bolt12Invoice::payment_paths`].
        ///
        /// # Errors
        ///
        /// Errors if a duplicate `payment_id` is provided given the caveats in the aforementioned link
        /// or if `amount_msats` is invalid.
        ///
        /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
        ///
        /// [`Refund`]: crate::offers::refund::Refund
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        /// [`Bolt12Invoice::payment_paths`]: crate::offers::invoice::Bolt12Invoice::payment_paths
        pub fn create_refund_builder(
                &self, description: String, amount_msats: u64, absolute_expiry: Duration,
                payment_id: PaymentId, retry_strategy: Retry, max_total_routing_fee_msat: Option<u64>
        ) -> Result<RefundBuilder<secp256k1::All>, Bolt12SemanticError> {
                let node_id = self.get_our_node_id();
                let expanded_key = &self.inbound_payment_key;
                let entropy = &*self.entropy_source;
                let secp_ctx = &self.secp_ctx;
                let path = self.create_one_hop_blinded_path();

                let builder = RefundBuilder::deriving_payer_id(
                        description, node_id, expanded_key, entropy, secp_ctx, amount_msats, payment_id
                )?
                        .chain_hash(self.chain_hash)
                        .absolute_expiry(absolute_expiry)
                        .path(path);

                let expiration = StaleExpiration::AbsoluteTimeout(absolute_expiry);
                self.pending_outbound_payments
                        .add_new_awaiting_invoice(
                                payment_id, expiration, retry_strategy, max_total_routing_fee_msat,
                        )
                        .map_err(|_| Bolt12SemanticError::DuplicatePaymentId)?;

                Ok(builder)
        }

        /// Pays for an [`Offer`] using the given parameters by creating an [`InvoiceRequest`] and
        /// enqueuing it to be sent via an onion message. [`ChannelManager`] will pay the actual
        /// [`Bolt12Invoice`] once it is received.
        ///
        /// Uses [`InvoiceRequestBuilder`] such that the [`InvoiceRequest`] it builds is recognized by
        /// the [`ChannelManager`] when handling a [`Bolt12Invoice`] message in response to the request.
        /// The optional parameters are used in the builder, if `Some`:
        /// - `quantity` for [`InvoiceRequest::quantity`] which must be set if
        ///   [`Offer::expects_quantity`] is `true`.
        /// - `amount_msats` if overpaying what is required for the given `quantity` is desired, and
        /// - `payer_note` for [`InvoiceRequest::payer_note`].
        ///
        /// If `max_total_routing_fee_msat` is not specified, The default from
        /// [`RouteParameters::from_payment_params_and_value`] is applied.
        ///
        /// # Payment
        ///
        /// The provided `payment_id` is used to ensure that only one invoice is paid for the request
        /// when received. See [Avoiding Duplicate Payments] for other requirements once the payment has
        /// been sent.
        ///
        /// To revoke the request, use [`ChannelManager::abandon_payment`] prior to receiving the
        /// invoice. If abandoned, or an invoice isn't received in a reasonable amount of time, the
        /// payment will fail with an [`Event::InvoiceRequestFailed`].
        ///
        /// # Privacy
        ///
        /// Uses a one-hop [`BlindedPath`] for the reply path with [`ChannelManager::get_our_node_id`]
        /// as the introduction node and a derived payer id for payer privacy. As such, currently, the
        /// node must be announced. Otherwise, there is no way to find a path to the introduction node
        /// in order to send the [`Bolt12Invoice`].
        ///
        /// # Limitations
        ///
        /// Requires a direct connection to an introduction node in [`Offer::paths`] or to
        /// [`Offer::signing_pubkey`], if empty. A similar restriction applies to the responding
        /// [`Bolt12Invoice::payment_paths`].
        ///
        /// # Errors
        ///
        /// Errors if a duplicate `payment_id` is provided given the caveats in the aforementioned link
        /// or if the provided parameters are invalid for the offer.
        ///
        /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
        /// [`InvoiceRequest::quantity`]: crate::offers::invoice_request::InvoiceRequest::quantity
        /// [`InvoiceRequest::payer_note`]: crate::offers::invoice_request::InvoiceRequest::payer_note
        /// [`InvoiceRequestBuilder`]: crate::offers::invoice_request::InvoiceRequestBuilder
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        /// [`Bolt12Invoice::payment_paths`]: crate::offers::invoice::Bolt12Invoice::payment_paths
        /// [Avoiding Duplicate Payments]: #avoiding-duplicate-payments
        pub fn pay_for_offer(
                &self, offer: &Offer, quantity: Option<u64>, amount_msats: Option<u64>,
                payer_note: Option<String>, payment_id: PaymentId, retry_strategy: Retry,
                max_total_routing_fee_msat: Option<u64>
        ) -> Result<(), Bolt12SemanticError> {
                let expanded_key = &self.inbound_payment_key;
                let entropy = &*self.entropy_source;
                let secp_ctx = &self.secp_ctx;

                let builder = offer
                        .request_invoice_deriving_payer_id(expanded_key, entropy, secp_ctx, payment_id)?
                        .chain_hash(self.chain_hash)?;
                let builder = match quantity {
                        None => builder,
                        Some(quantity) => builder.quantity(quantity)?,
                };
                let builder = match amount_msats {
                        None => builder,
                        Some(amount_msats) => builder.amount_msats(amount_msats)?,
                };
                let builder = match payer_note {
                        None => builder,
                        Some(payer_note) => builder.payer_note(payer_note),
                };

                let invoice_request = builder.build_and_sign()?;
                let reply_path = self.create_one_hop_blinded_path();

                let expiration = StaleExpiration::TimerTicks(1);
                self.pending_outbound_payments
                        .add_new_awaiting_invoice(
                                payment_id, expiration, retry_strategy, max_total_routing_fee_msat
                        )
                        .map_err(|_| Bolt12SemanticError::DuplicatePaymentId)?;

                let mut pending_offers_messages = self.pending_offers_messages.lock().unwrap();
                if offer.paths().is_empty() {
                        let message = new_pending_onion_message(
                                OffersMessage::InvoiceRequest(invoice_request),
                                Destination::Node(offer.signing_pubkey()),
                                Some(reply_path),
                        );
                        pending_offers_messages.push(message);
                } else {
                        // Send as many invoice requests as there are paths in the offer (with an upper bound).
                        // Using only one path could result in a failure if the path no longer exists. But only
                        // one invoice for a given payment id will be paid, even if more than one is received.
                        const REQUEST_LIMIT: usize = 10;
                        for path in offer.paths().into_iter().take(REQUEST_LIMIT) {
                                let message = new_pending_onion_message(
                                        OffersMessage::InvoiceRequest(invoice_request.clone()),
                                        Destination::BlindedPath(path.clone()),
                                        Some(reply_path.clone()),
                                );
                                pending_offers_messages.push(message);
                        }
                }

                Ok(())
        }

        /// Creates a [`Bolt12Invoice`] for a [`Refund`] and enqueues it to be sent via an onion
        /// message.
        ///
        /// The resulting invoice uses a [`PaymentHash`] recognized by the [`ChannelManager`] and a
        /// [`BlindedPath`] containing the [`PaymentSecret`] needed to reconstruct the corresponding
        /// [`PaymentPreimage`].
        ///
        /// # Limitations
        ///
        /// Requires a direct connection to an introduction node in [`Refund::paths`] or to
        /// [`Refund::payer_id`], if empty. This request is best effort; an invoice will be sent to each
        /// node meeting the aforementioned criteria, but there's no guarantee that they will be
        /// received and no retries will be made.
        ///
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        pub fn request_refund_payment(&self, refund: &Refund) -> Result<(), Bolt12SemanticError> {
                let expanded_key = &self.inbound_payment_key;
                let entropy = &*self.entropy_source;
                let secp_ctx = &self.secp_ctx;

                let amount_msats = refund.amount_msats();
                let relative_expiry = DEFAULT_RELATIVE_EXPIRY.as_secs() as u32;

                match self.create_inbound_payment(Some(amount_msats), relative_expiry, None) {
                        Ok((payment_hash, payment_secret)) => {
                                let payment_paths = vec![
                                        self.create_one_hop_blinded_payment_path(payment_secret),
                                ];
                                #[cfg(not(feature = "no-std"))]
                                let builder = refund.respond_using_derived_keys(
                                        payment_paths, payment_hash, expanded_key, entropy
                                )?;
                                #[cfg(feature = "no-std")]
                                let created_at = Duration::from_secs(
                                        self.highest_seen_timestamp.load(Ordering::Acquire) as u64
                                );
                                #[cfg(feature = "no-std")]
                                let builder = refund.respond_using_derived_keys_no_std(
                                        payment_paths, payment_hash, created_at, expanded_key, entropy
                                )?;
                                let invoice = builder.allow_mpp().build_and_sign(secp_ctx)?;
                                let reply_path = self.create_one_hop_blinded_path();

                                let mut pending_offers_messages = self.pending_offers_messages.lock().unwrap();
                                if refund.paths().is_empty() {
                                        let message = new_pending_onion_message(
                                                OffersMessage::Invoice(invoice),
                                                Destination::Node(refund.payer_id()),
                                                Some(reply_path),
                                        );
                                        pending_offers_messages.push(message);
                                } else {
                                        for path in refund.paths() {
                                                let message = new_pending_onion_message(
                                                        OffersMessage::Invoice(invoice.clone()),
                                                        Destination::BlindedPath(path.clone()),
                                                        Some(reply_path.clone()),
                                                );
                                                pending_offers_messages.push(message);
                                        }
                                }

                                Ok(())
                        },
                        Err(()) => Err(Bolt12SemanticError::InvalidAmount),
                }
        }

        /// Gets a payment secret and payment hash for use in an invoice given to a third party wishing
        /// to pay us.
        ///
        /// This differs from [`create_inbound_payment_for_hash`] only in that it generates the
        /// [`PaymentHash`] and [`PaymentPreimage`] for you.
        ///
        /// The [`PaymentPreimage`] will ultimately be returned to you in the [`PaymentClaimable`], which
        /// will have the [`PaymentClaimable::purpose`] be [`PaymentPurpose::InvoicePayment`] with
        /// its [`PaymentPurpose::InvoicePayment::payment_preimage`] field filled in. That should then be
        /// passed directly to [`claim_funds`].
        ///
        /// See [`create_inbound_payment_for_hash`] for detailed documentation on behavior and requirements.
        ///
        /// Note that a malicious eavesdropper can intuit whether an inbound payment was created by
        /// `create_inbound_payment` or `create_inbound_payment_for_hash` based on runtime.
        ///
        /// # Note
        ///
        /// If you register an inbound payment with this method, then serialize the `ChannelManager`, then
        /// deserialize it with a node running 0.0.103 and earlier, the payment will fail to be received.
        ///
        /// Errors if `min_value_msat` is greater than total bitcoin supply.
        ///
        /// If `min_final_cltv_expiry_delta` is set to some value, then the payment will not be receivable
        /// on versions of LDK prior to 0.0.114.
        ///
        /// [`claim_funds`]: Self::claim_funds
        /// [`PaymentClaimable`]: events::Event::PaymentClaimable
        /// [`PaymentClaimable::purpose`]: events::Event::PaymentClaimable::purpose
        /// [`PaymentPurpose::InvoicePayment`]: events::PaymentPurpose::InvoicePayment
        /// [`PaymentPurpose::InvoicePayment::payment_preimage`]: events::PaymentPurpose::InvoicePayment::payment_preimage
        /// [`create_inbound_payment_for_hash`]: Self::create_inbound_payment_for_hash
        pub fn create_inbound_payment(&self, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32,
                min_final_cltv_expiry_delta: Option<u16>) -> Result<(PaymentHash, PaymentSecret), ()> {
                inbound_payment::create(&self.inbound_payment_key, min_value_msat, invoice_expiry_delta_secs,
                        &self.entropy_source, self.highest_seen_timestamp.load(Ordering::Acquire) as u64,
                        min_final_cltv_expiry_delta)
        }

        /// Gets a [`PaymentSecret`] for a given [`PaymentHash`], for which the payment preimage is
        /// stored external to LDK.
        ///
        /// A [`PaymentClaimable`] event will only be generated if the [`PaymentSecret`] matches a
        /// payment secret fetched via this method or [`create_inbound_payment`], and which is at least
        /// the `min_value_msat` provided here, if one is provided.
        ///
        /// The [`PaymentHash`] (and corresponding [`PaymentPreimage`]) should be globally unique, though
        /// note that LDK will not stop you from registering duplicate payment hashes for inbound
        /// payments.
        ///
        /// `min_value_msat` should be set if the invoice being generated contains a value. Any payment
        /// received for the returned [`PaymentHash`] will be required to be at least `min_value_msat`
        /// before a [`PaymentClaimable`] event will be generated, ensuring that we do not provide the
        /// sender "proof-of-payment" unless they have paid the required amount.
        ///
        /// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
        /// in excess of the current time. This should roughly match the expiry time set in the invoice.
        /// After this many seconds, we will remove the inbound payment, resulting in any attempts to
        /// pay the invoice failing. The BOLT spec suggests 3,600 secs as a default validity time for
        /// invoices when no timeout is set.
        ///
        /// Note that we use block header time to time-out pending inbound payments (with some margin
        /// to compensate for the inaccuracy of block header timestamps). Thus, in practice we will
        /// accept a payment and generate a [`PaymentClaimable`] event for some time after the expiry.
        /// If you need exact expiry semantics, you should enforce them upon receipt of
        /// [`PaymentClaimable`].
        ///
        /// Note that invoices generated for inbound payments should have their `min_final_cltv_expiry_delta`
        /// set to at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`].
        ///
        /// Note that a malicious eavesdropper can intuit whether an inbound payment was created by
        /// `create_inbound_payment` or `create_inbound_payment_for_hash` based on runtime.
        ///
        /// # Note
        ///
        /// If you register an inbound payment with this method, then serialize the `ChannelManager`, then
        /// deserialize it with a node running 0.0.103 and earlier, the payment will fail to be received.
        ///
        /// Errors if `min_value_msat` is greater than total bitcoin supply.
        ///
        /// If `min_final_cltv_expiry_delta` is set to some value, then the payment will not be receivable
        /// on versions of LDK prior to 0.0.114.
        ///
        /// [`create_inbound_payment`]: Self::create_inbound_payment
        /// [`PaymentClaimable`]: events::Event::PaymentClaimable
        pub fn create_inbound_payment_for_hash(&self, payment_hash: PaymentHash, min_value_msat: Option<u64>,
                invoice_expiry_delta_secs: u32, min_final_cltv_expiry: Option<u16>) -> Result<PaymentSecret, ()> {
                inbound_payment::create_from_hash(&self.inbound_payment_key, min_value_msat, payment_hash,
                        invoice_expiry_delta_secs, self.highest_seen_timestamp.load(Ordering::Acquire) as u64,
                        min_final_cltv_expiry)
        }

        /// Gets an LDK-generated payment preimage from a payment hash and payment secret that were
        /// previously returned from [`create_inbound_payment`].
        ///
        /// [`create_inbound_payment`]: Self::create_inbound_payment
        pub fn get_payment_preimage(&self, payment_hash: PaymentHash, payment_secret: PaymentSecret) -> Result<PaymentPreimage, APIError> {
                inbound_payment::get_payment_preimage(payment_hash, payment_secret, &self.inbound_payment_key)
        }

        /// Creates a one-hop blinded path with [`ChannelManager::get_our_node_id`] as the introduction
        /// node.
        fn create_one_hop_blinded_path(&self) -> BlindedPath {
                let entropy_source = self.entropy_source.deref();
                let secp_ctx = &self.secp_ctx;
                BlindedPath::one_hop_for_message(self.get_our_node_id(), entropy_source, secp_ctx).unwrap()
        }

        /// Creates a one-hop blinded path with [`ChannelManager::get_our_node_id`] as the introduction
        /// node.
        fn create_one_hop_blinded_payment_path(
                &self, payment_secret: PaymentSecret
        ) -> (BlindedPayInfo, BlindedPath) {
                let entropy_source = self.entropy_source.deref();
                let secp_ctx = &self.secp_ctx;

                let payee_node_id = self.get_our_node_id();
                let max_cltv_expiry = self.best_block.read().unwrap().height() + LATENCY_GRACE_PERIOD_BLOCKS;
                let payee_tlvs = ReceiveTlvs {
                        payment_secret,
                        payment_constraints: PaymentConstraints {
                                max_cltv_expiry,
                                htlc_minimum_msat: 1,
                        },
                };
                // TODO: Err for overflow?
                BlindedPath::one_hop_for_payment(
                        payee_node_id, payee_tlvs, entropy_source, secp_ctx
                ).unwrap()
        }

        /// Gets a fake short channel id for use in receiving [phantom node payments]. These fake scids
        /// are used when constructing the phantom invoice's route hints.
        ///
        /// [phantom node payments]: crate::sign::PhantomKeysManager
        pub fn get_phantom_scid(&self) -> u64 {
                let best_block_height = self.best_block.read().unwrap().height();
                let short_to_chan_info = self.short_to_chan_info.read().unwrap();
                loop {
                        let scid_candidate = fake_scid::Namespace::Phantom.get_fake_scid(best_block_height, &self.chain_hash, &self.fake_scid_rand_bytes, &self.entropy_source);
                        // Ensure the generated scid doesn't conflict with a real channel.
                        match short_to_chan_info.get(&scid_candidate) {
                                Some(_) => continue,
                                None => return scid_candidate
                        }
                }
        }

        /// Gets route hints for use in receiving [phantom node payments].
        ///
        /// [phantom node payments]: crate::sign::PhantomKeysManager
        pub fn get_phantom_route_hints(&self) -> PhantomRouteHints {
                PhantomRouteHints {
                        channels: self.list_usable_channels(),
                        phantom_scid: self.get_phantom_scid(),
                        real_node_pubkey: self.get_our_node_id(),
                }
        }

        /// Gets a fake short channel id for use in receiving intercepted payments. These fake scids are
        /// used when constructing the route hints for HTLCs intended to be intercepted. See
        /// [`ChannelManager::forward_intercepted_htlc`].
        ///
        /// Note that this method is not guaranteed to return unique values, you may need to call it a few
        /// times to get a unique scid.
        pub fn get_intercept_scid(&self) -> u64 {
                let best_block_height = self.best_block.read().unwrap().height();
                let short_to_chan_info = self.short_to_chan_info.read().unwrap();
                loop {
                        let scid_candidate = fake_scid::Namespace::Intercept.get_fake_scid(best_block_height, &self.chain_hash, &self.fake_scid_rand_bytes, &self.entropy_source);
                        // Ensure the generated scid doesn't conflict with a real channel.
                        if short_to_chan_info.contains_key(&scid_candidate) { continue }
                        return scid_candidate
                }
        }

        /// Gets inflight HTLC information by processing pending outbound payments that are in
        /// our channels. May be used during pathfinding to account for in-use channel liquidity.
        pub fn compute_inflight_htlcs(&self) -> InFlightHtlcs {
                let mut inflight_htlcs = InFlightHtlcs::new();

                let per_peer_state = self.per_peer_state.read().unwrap();
                for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        for chan in peer_state.channel_by_id.values().filter_map(
                                |phase| if let ChannelPhase::Funded(chan) = phase { Some(chan) } else { None }
                        ) {
                                for (htlc_source, _) in chan.inflight_htlc_sources() {
                                        if let HTLCSource::OutboundRoute { path, .. } = htlc_source {
                                                inflight_htlcs.process_path(path, self.get_our_node_id());
                                        }
                                }
                        }
                }

                inflight_htlcs
        }

        #[cfg(any(test, feature = "_test_utils"))]
        pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
                let events = core::cell::RefCell::new(Vec::new());
                let event_handler = |event: events::Event| events.borrow_mut().push(event);
                self.process_pending_events(&event_handler);
                events.into_inner()
        }

        #[cfg(feature = "_test_utils")]
        pub fn push_pending_event(&self, event: events::Event) {
                let mut events = self.pending_events.lock().unwrap();
                events.push_back((event, None));
        }

        #[cfg(test)]
        pub fn pop_pending_event(&self) -> Option<events::Event> {
                let mut events = self.pending_events.lock().unwrap();
                events.pop_front().map(|(e, _)| e)
        }

        #[cfg(test)]
        pub fn has_pending_payments(&self) -> bool {
                self.pending_outbound_payments.has_pending_payments()
        }

        #[cfg(test)]
        pub fn clear_pending_payments(&self) {
                self.pending_outbound_payments.clear_pending_payments()
        }

        /// When something which was blocking a channel from updating its [`ChannelMonitor`] (e.g. an
        /// [`Event`] being handled) completes, this should be called to restore the channel to normal
        /// operation. It will double-check that nothing *else* is also blocking the same channel from
        /// making progress and then let any blocked [`ChannelMonitorUpdate`]s fly.
        fn handle_monitor_update_release(&self, counterparty_node_id: PublicKey, channel_funding_outpoint: OutPoint, mut completed_blocker: Option<RAAMonitorUpdateBlockingAction>) {
                loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        if let Some(peer_state_mtx) = per_peer_state.get(&counterparty_node_id) {
                                let mut peer_state_lck = peer_state_mtx.lock().unwrap();
                                let peer_state = &mut *peer_state_lck;

                                if let Some(blocker) = completed_blocker.take() {
                                        // Only do this on the first iteration of the loop.
                                        if let Some(blockers) = peer_state.actions_blocking_raa_monitor_updates
                                                .get_mut(&channel_funding_outpoint.to_channel_id())
                                        {
                                                blockers.retain(|iter| iter != &blocker);
                                        }
                                }

                                if self.raa_monitor_updates_held(&peer_state.actions_blocking_raa_monitor_updates,
                                        channel_funding_outpoint, counterparty_node_id) {
                                        // Check that, while holding the peer lock, we don't have anything else
                                        // blocking monitor updates for this channel. If we do, release the monitor
                                        // update(s) when those blockers complete.
                                        log_trace!(self.logger, "Delaying monitor unlock for channel {} as another channel's mon update needs to complete first",
                                                &channel_funding_outpoint.to_channel_id());
                                        break;
                                }

                                if let hash_map::Entry::Occupied(mut chan_phase_entry) = peer_state.channel_by_id.entry(channel_funding_outpoint.to_channel_id()) {
                                        if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
                                                debug_assert_eq!(chan.context.get_funding_txo().unwrap(), channel_funding_outpoint);
                                                if let Some((monitor_update, further_update_exists)) = chan.unblock_next_blocked_monitor_update() {
                                                        log_debug!(self.logger, "Unlocking monitor updating for channel {} and updating monitor",
                                                                channel_funding_outpoint.to_channel_id());
                                                        handle_new_monitor_update!(self, channel_funding_outpoint, monitor_update,
                                                                peer_state_lck, peer_state, per_peer_state, chan);
                                                        if further_update_exists {
                                                                // If there are more `ChannelMonitorUpdate`s to process, restart at the
                                                                // top of the loop.
                                                                continue;
                                                        }
                                                } else {
                                                        log_trace!(self.logger, "Unlocked monitor updating for channel {} without monitors to update",
                                                                channel_funding_outpoint.to_channel_id());
                                                }
                                        }
                                }
                        } else {
                                log_debug!(self.logger,
                                        "Got a release post-RAA monitor update for peer {} but the channel is gone",
                                        log_pubkey!(counterparty_node_id));
                        }
                        break;
                }
        }

        fn handle_post_event_actions(&self, actions: Vec<EventCompletionAction>) {
                for action in actions {
                        match action {
                                EventCompletionAction::ReleaseRAAChannelMonitorUpdate {
                                        channel_funding_outpoint, counterparty_node_id
                                } => {
                                        self.handle_monitor_update_release(counterparty_node_id, channel_funding_outpoint, None);
                                }
                        }
                }
        }

        /// Processes any events asynchronously in the order they were generated since the last call
        /// using the given event handler.
        ///
        /// See the trait-level documentation of [`EventsProvider`] for requirements.
        pub async fn process_pending_events_async<Future: core::future::Future, H: Fn(Event) -> Future>(
                &self, handler: H
        ) {
                let mut ev;
                process_events_body!(self, ev, { handler(ev).await });
        }
}

fn create_fwd_pending_htlc_info(
        msg: &msgs::UpdateAddHTLC, hop_data: msgs::InboundOnionPayload, hop_hmac: [u8; 32],
        new_packet_bytes: [u8; onion_utils::ONION_DATA_LEN], shared_secret: [u8; 32],
        next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
) -> Result<PendingHTLCInfo, InboundOnionErr> {
        debug_assert!(next_packet_pubkey_opt.is_some());
        let outgoing_packet = msgs::OnionPacket {
                version: 0,
                public_key: next_packet_pubkey_opt.unwrap_or(Err(secp256k1::Error::InvalidPublicKey)),
                hop_data: new_packet_bytes,
                hmac: hop_hmac,
        };

        let (short_channel_id, amt_to_forward, outgoing_cltv_value) = match hop_data {
                msgs::InboundOnionPayload::Forward { short_channel_id, amt_to_forward, outgoing_cltv_value } =>
                        (short_channel_id, amt_to_forward, outgoing_cltv_value),
                msgs::InboundOnionPayload::Receive { .. } | msgs::InboundOnionPayload::BlindedReceive { .. } =>
                        return Err(InboundOnionErr {
                                msg: "Final Node OnionHopData provided for us as an intermediary node",
                                err_code: 0x4000 | 22,
                                err_data: Vec::new(),
                        }),
        };

        Ok(PendingHTLCInfo {
                routing: PendingHTLCRouting::Forward {
                        onion_packet: outgoing_packet,
                        short_channel_id,
                },
                payment_hash: msg.payment_hash,
                incoming_shared_secret: shared_secret,
                incoming_amt_msat: Some(msg.amount_msat),
                outgoing_amt_msat: amt_to_forward,
                outgoing_cltv_value,
                skimmed_fee_msat: None,
        })
}

fn create_recv_pending_htlc_info(
        hop_data: msgs::InboundOnionPayload, shared_secret: [u8; 32], payment_hash: PaymentHash,
        amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>, allow_underpay: bool,
        counterparty_skimmed_fee_msat: Option<u64>, current_height: u32, accept_mpp_keysend: bool,
) -> Result<PendingHTLCInfo, InboundOnionErr> {
        let (payment_data, keysend_preimage, custom_tlvs, onion_amt_msat, outgoing_cltv_value, payment_metadata) = match hop_data {
                msgs::InboundOnionPayload::Receive {
                        payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata, ..
                } =>
                        (payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata),
                msgs::InboundOnionPayload::BlindedReceive {
                        amt_msat, total_msat, outgoing_cltv_value, payment_secret, ..
                } => {
                        let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
                        (Some(payment_data), None, Vec::new(), amt_msat, outgoing_cltv_value, None)
                }
                msgs::InboundOnionPayload::Forward { .. } => {
                        return Err(InboundOnionErr {
                                err_code: 0x4000|22,
                                err_data: Vec::new(),
                                msg: "Got non final data with an HMAC of 0",
                        })
                },
        };
        // final_incorrect_cltv_expiry
        if outgoing_cltv_value > cltv_expiry {
                return Err(InboundOnionErr {
                        msg: "Upstream node set CLTV to less than the CLTV set by the sender",
                        err_code: 18,
                        err_data: cltv_expiry.to_be_bytes().to_vec()
                })
        }
        // final_expiry_too_soon
        // We have to have some headroom to broadcast on chain if we have the preimage, so make sure
        // we have at least HTLC_FAIL_BACK_BUFFER blocks to go.
        //
        // Also, ensure that, in the case of an unknown preimage for the received payment hash, our
        // payment logic has enough time to fail the HTLC backward before our onchain logic triggers a
        // channel closure (see HTLC_FAIL_BACK_BUFFER rationale).
        if cltv_expiry <= current_height + HTLC_FAIL_BACK_BUFFER + 1 {
                let mut err_data = Vec::with_capacity(12);
                err_data.extend_from_slice(&amt_msat.to_be_bytes());
                err_data.extend_from_slice(&current_height.to_be_bytes());
                return Err(InboundOnionErr {
                        err_code: 0x4000 | 15, err_data,
                        msg: "The final CLTV expiry is too soon to handle",
                });
        }
        if (!allow_underpay && onion_amt_msat > amt_msat) ||
                (allow_underpay && onion_amt_msat >
                 amt_msat.saturating_add(counterparty_skimmed_fee_msat.unwrap_or(0)))
        {
                return Err(InboundOnionErr {
                        err_code: 19,
                        err_data: amt_msat.to_be_bytes().to_vec(),
                        msg: "Upstream node sent less than we were supposed to receive in payment",
                });
        }

        let routing = if let Some(payment_preimage) = keysend_preimage {
                // We need to check that the sender knows the keysend preimage before processing this
                // payment further. Otherwise, an intermediary routing hop forwarding non-keysend-HTLC X
                // could discover the final destination of X, by probing the adjacent nodes on the route
                // with a keysend payment of identical payment hash to X and observing the processing
                // time discrepancies due to a hash collision with X.
                let hashed_preimage = PaymentHash(Sha256::hash(&payment_preimage.0).to_byte_array());
                if hashed_preimage != payment_hash {
                        return Err(InboundOnionErr {
                                err_code: 0x4000|22,
                                err_data: Vec::new(),
                                msg: "Payment preimage didn't match payment hash",
                        });
                }
                if !accept_mpp_keysend && payment_data.is_some() {
                        return Err(InboundOnionErr {
                                err_code: 0x4000|22,
                                err_data: Vec::new(),
                                msg: "We don't support MPP keysend payments",
                        });
                }
                PendingHTLCRouting::ReceiveKeysend {
                        payment_data,
                        payment_preimage,
                        payment_metadata,
                        incoming_cltv_expiry: outgoing_cltv_value,
                        custom_tlvs,
                }
        } else if let Some(data) = payment_data {
                PendingHTLCRouting::Receive {
                        payment_data: data,
                        payment_metadata,
                        incoming_cltv_expiry: outgoing_cltv_value,
                        phantom_shared_secret,
                        custom_tlvs,
                }
        } else {
                return Err(InboundOnionErr {
                        err_code: 0x4000|0x2000|3,
                        err_data: Vec::new(),
                        msg: "We require payment_secrets",
                });
        };
        Ok(PendingHTLCInfo {
                routing,
                payment_hash,
                incoming_shared_secret: shared_secret,
                incoming_amt_msat: Some(amt_msat),
                outgoing_amt_msat: onion_amt_msat,
                outgoing_cltv_value,
                skimmed_fee_msat: counterparty_skimmed_fee_msat,
        })
}

/// Peel one layer off an incoming onion, returning [`PendingHTLCInfo`] (either Forward or Receive).
/// This does all the relevant context-free checks that LDK requires for payment relay or
/// acceptance. If the payment is to be received, and the amount matches the expected amount for
/// a given invoice, this indicates the [`msgs::UpdateAddHTLC`], once fully committed in the
/// channel, will generate an [`Event::PaymentClaimable`].
pub fn peel_payment_onion<NS: Deref, L: Deref, T: secp256k1::Verification>(
        msg: &msgs::UpdateAddHTLC, node_signer: &NS, logger: &L, secp_ctx: &Secp256k1<T>,
        cur_height: u32, accept_mpp_keysend: bool,
) -> Result<PendingHTLCInfo, InboundOnionErr>
where
        NS::Target: NodeSigner,
        L::Target: Logger,
{
        let (hop, shared_secret, next_packet_details_opt) =
                decode_incoming_update_add_htlc_onion(msg, node_signer, logger, secp_ctx
        ).map_err(|e| {
                let (err_code, err_data) = match e {
                        HTLCFailureMsg::Malformed(m) => (m.failure_code, Vec::new()),
                        HTLCFailureMsg::Relay(r) => (0x4000 | 22, r.reason.data),
                };
                let msg = "Failed to decode update add htlc onion";
                InboundOnionErr { msg, err_code, err_data }
        })?;
        Ok(match hop {
                onion_utils::Hop::Forward { next_hop_data, next_hop_hmac, new_packet_bytes } => {
                        let NextPacketDetails {
                                next_packet_pubkey, outgoing_amt_msat: _, outgoing_scid: _, outgoing_cltv_value
                        } = match next_packet_details_opt {
                                Some(next_packet_details) => next_packet_details,
                                // Forward should always include the next hop details
                                None => return Err(InboundOnionErr {
                                        msg: "Failed to decode update add htlc onion",
                                        err_code: 0x4000 | 22,
                                        err_data: Vec::new(),
                                }),
                        };

                        if let Err((err_msg, code)) = check_incoming_htlc_cltv(
                                cur_height, outgoing_cltv_value, msg.cltv_expiry
                        ) {
                                return Err(InboundOnionErr {
                                        msg: err_msg,
                                        err_code: code,
                                        err_data: Vec::new(),
                                });
                        }
                        create_fwd_pending_htlc_info(
                                msg, next_hop_data, next_hop_hmac, new_packet_bytes, shared_secret,
                                Some(next_packet_pubkey)
                        )?
                },
                onion_utils::Hop::Receive(received_data) => {
                        create_recv_pending_htlc_info(
                                received_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry,
                                None, false, msg.skimmed_fee_msat, cur_height, accept_mpp_keysend,
                        )?
                }
        })
}

struct NextPacketDetails {
        next_packet_pubkey: Result<PublicKey, secp256k1::Error>,
        outgoing_scid: u64,
        outgoing_amt_msat: u64,
        outgoing_cltv_value: u32,
}

fn decode_incoming_update_add_htlc_onion<NS: Deref, L: Deref, T: secp256k1::Verification>(
        msg: &msgs::UpdateAddHTLC, node_signer: &NS, logger: &L, secp_ctx: &Secp256k1<T>,
) -> Result<(onion_utils::Hop, [u8; 32], Option<NextPacketDetails>), HTLCFailureMsg>
where
        NS::Target: NodeSigner,
        L::Target: Logger,
{
        macro_rules! return_malformed_err {
                ($msg: expr, $err_code: expr) => {
                        {
                                log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                return Err(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
                                        channel_id: msg.channel_id,
                                        htlc_id: msg.htlc_id,
                                        sha256_of_onion: Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(),
                                        failure_code: $err_code,
                                }));
                        }
                }
        }

        if let Err(_) = msg.onion_routing_packet.public_key {
                return_malformed_err!("invalid ephemeral pubkey", 0x8000 | 0x4000 | 6);
        }

        let shared_secret = node_signer.ecdh(
                Recipient::Node, &msg.onion_routing_packet.public_key.unwrap(), None
        ).unwrap().secret_bytes();

        if msg.onion_routing_packet.version != 0 {
                //TODO: Spec doesn't indicate if we should only hash hop_data here (and in other
                //sha256_of_onion error data packets), or the entire onion_routing_packet. Either way,
                //the hash doesn't really serve any purpose - in the case of hashing all data, the
                //receiving node would have to brute force to figure out which version was put in the
                //packet by the node that send us the message, in the case of hashing the hop_data, the
                //node knows the HMAC matched, so they already know what is there...
                return_malformed_err!("Unknown onion packet version", 0x8000 | 0x4000 | 4);
        }
        macro_rules! return_err {
                ($msg: expr, $err_code: expr, $data: expr) => {
                        {
                                log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
                                        channel_id: msg.channel_id,
                                        htlc_id: msg.htlc_id,
                                        reason: HTLCFailReason::reason($err_code, $data.to_vec())
                                                .get_encrypted_failure_packet(&shared_secret, &None),
                                }));
                        }
                }
        }

        let next_hop = match onion_utils::decode_next_payment_hop(
                shared_secret, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
                msg.payment_hash, node_signer
        ) {
                Ok(res) => res,
                Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
                        return_malformed_err!(err_msg, err_code);
                },
                Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code }) => {
                        return_err!(err_msg, err_code, &[0; 0]);
                },
        };

        let next_packet_details = match next_hop {
                onion_utils::Hop::Forward {
                        next_hop_data: msgs::InboundOnionPayload::Forward {
                                short_channel_id, amt_to_forward, outgoing_cltv_value
                        }, ..
                } => {
                        let next_packet_pubkey = onion_utils::next_hop_pubkey(secp_ctx,
                                msg.onion_routing_packet.public_key.unwrap(), &shared_secret);
                        NextPacketDetails {
                                next_packet_pubkey, outgoing_scid: short_channel_id,
                                outgoing_amt_msat: amt_to_forward, outgoing_cltv_value
                        }
                },
                onion_utils::Hop::Receive { .. } => return Ok((next_hop, shared_secret, None)),
                onion_utils::Hop::Forward { next_hop_data: msgs::InboundOnionPayload::Receive { .. }, .. } |
                        onion_utils::Hop::Forward { next_hop_data: msgs::InboundOnionPayload::BlindedReceive { .. }, .. } =>
                {
                        return_err!("Final Node OnionHopData provided for us as an intermediary node", 0x4000 | 22, &[0; 0]);
                }
        };

        Ok((next_hop, shared_secret, Some(next_packet_details)))
}

fn check_incoming_htlc_cltv(
        cur_height: u32, outgoing_cltv_value: u32, cltv_expiry: u32
) -> Result<(), (&'static str, u16)> {
        if (cltv_expiry as u64) < (outgoing_cltv_value) as u64 + MIN_CLTV_EXPIRY_DELTA as u64 {
                return Err((
                        "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
                        0x1000 | 13, // incorrect_cltv_expiry
                ));
        }
        // Theoretically, channel counterparty shouldn't send us a HTLC expiring now,
        // but we want to be robust wrt to counterparty packet sanitization (see
        // HTLC_FAIL_BACK_BUFFER rationale).
        if cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon
                return Err(("CLTV expiry is too close", 0x1000 | 14));
        }
        if cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far
                return Err(("CLTV expiry is too far in the future", 21));
        }
        // If the HTLC expires ~now, don't bother trying to forward it to our
        // counterparty. They should fail it anyway, but we don't want to bother with
        // the round-trips or risk them deciding they definitely want the HTLC and
        // force-closing to ensure they get it if we're offline.
        // We previously had a much more aggressive check here which tried to ensure
        // our counterparty receives an HTLC which has *our* risk threshold met on it,
        // but there is no need to do that, and since we're a bit conservative with our
        // risk threshold it just results in failing to forward payments.
        if (outgoing_cltv_value) as u64 <= (cur_height + LATENCY_GRACE_PERIOD_BLOCKS) as u64 {
                return Err(("Outgoing CLTV value is too soon", 0x1000 | 14));
        }

        Ok(())
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> MessageSendEventsProvider for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        /// Returns `MessageSendEvent`s strictly ordered per-peer, in the order they were generated.
        /// The returned array will contain `MessageSendEvent`s for different peers if
        /// `MessageSendEvent`s to more than one peer exists, but `MessageSendEvent`s to the same peer
        /// is always placed next to each other.
        ///
        /// Note that that while `MessageSendEvent`s are strictly ordered per-peer, the peer order for
        /// the chunks of `MessageSendEvent`s for different peers is random. I.e. if the array contains
        /// `MessageSendEvent`s  for both `node_a` and `node_b`, the `MessageSendEvent`s for `node_a`
        /// will randomly be placed first or last in the returned array.
        ///
        /// Note that even though `BroadcastChannelAnnouncement` and `BroadcastChannelUpdate`
        /// `MessageSendEvent`s are intended to be broadcasted to all peers, they will be pleaced among
        /// the `MessageSendEvent`s to the specific peer they were generated under.
        fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
                let events = RefCell::new(Vec::new());
                PersistenceNotifierGuard::optionally_notify(self, || {
                        let mut result = NotifyOption::SkipPersistNoEvents;

                        // TODO: This behavior should be documented. It's unintuitive that we query
                        // ChannelMonitors when clearing other events.
                        if self.process_pending_monitor_events() {
                                result = NotifyOption::DoPersist;
                        }

                        if self.check_free_holding_cells() {
                                result = NotifyOption::DoPersist;
                        }
                        if self.maybe_generate_initial_closing_signed() {
                                result = NotifyOption::DoPersist;
                        }

                        let mut pending_events = Vec::new();
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                if peer_state.pending_msg_events.len() > 0 {
                                        pending_events.append(&mut peer_state.pending_msg_events);
                                }
                        }

                        if !pending_events.is_empty() {
                                events.replace(pending_events);
                        }

                        result
                });
                events.into_inner()
        }
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> EventsProvider for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        /// Processes events that must be periodically handled.
        ///
        /// An [`EventHandler`] may safely call back to the provider in order to handle an event.
        /// However, it must not call [`Writeable::write`] as doing so would result in a deadlock.
        fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
                let mut ev;
                process_events_body!(self, ev, handler.handle_event(ev));
        }
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> chain::Listen for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        fn filtered_block_connected(&self, header: &Header, txdata: &TransactionData, height: u32) {
                {
                        let best_block = self.best_block.read().unwrap();
                        assert_eq!(best_block.block_hash(), header.prev_blockhash,
                                "Blocks must be connected in chain-order - the connected header must build on the last connected header");
                        assert_eq!(best_block.height(), height - 1,
                                "Blocks must be connected in chain-order - the connected block height must be one greater than the previous height");
                }

                self.transactions_confirmed(header, txdata, height);
                self.best_block_updated(header, height);
        }

        fn block_disconnected(&self, header: &Header, height: u32) {
                let _persistence_guard =
                        PersistenceNotifierGuard::optionally_notify_skipping_background_events(
                                self, || -> NotifyOption { NotifyOption::DoPersist });
                let new_height = height - 1;
                {
                        let mut best_block = self.best_block.write().unwrap();
                        assert_eq!(best_block.block_hash(), header.block_hash(),
                                "Blocks must be disconnected in chain-order - the disconnected header must be the last connected header");
                        assert_eq!(best_block.height(), height,
                                "Blocks must be disconnected in chain-order - the disconnected block must have the correct height");
                        *best_block = BestBlock::new(header.prev_blockhash, new_height)
                }

                self.do_chain_event(Some(new_height), |channel| channel.best_block_updated(new_height, header.time, self.chain_hash, &self.node_signer, &self.default_configuration, &self.logger));
        }
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> chain::Confirm for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        fn transactions_confirmed(&self, header: &Header, txdata: &TransactionData, height: u32) {
                // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
                // during initialization prior to the chain_monitor being fully configured in some cases.
                // See the docs for `ChannelManagerReadArgs` for more.

                let block_hash = header.block_hash();
                log_trace!(self.logger, "{} transactions included in block {} at height {} provided", txdata.len(), block_hash, height);

                let _persistence_guard =
                        PersistenceNotifierGuard::optionally_notify_skipping_background_events(
                                self, || -> NotifyOption { NotifyOption::DoPersist });
                self.do_chain_event(Some(height), |channel| channel.transactions_confirmed(&block_hash, height, txdata, self.chain_hash, &self.node_signer, &self.default_configuration, &self.logger)
                        .map(|(a, b)| (a, Vec::new(), b)));

                let last_best_block_height = self.best_block.read().unwrap().height();
                if height < last_best_block_height {
                        let timestamp = self.highest_seen_timestamp.load(Ordering::Acquire);
                        self.do_chain_event(Some(last_best_block_height), |channel| channel.best_block_updated(last_best_block_height, timestamp as u32, self.chain_hash, &self.node_signer, &self.default_configuration, &self.logger));
                }
        }

        fn best_block_updated(&self, header: &Header, height: u32) {
                // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
                // during initialization prior to the chain_monitor being fully configured in some cases.
                // See the docs for `ChannelManagerReadArgs` for more.

                let block_hash = header.block_hash();
                log_trace!(self.logger, "New best block: {} at height {}", block_hash, height);

                let _persistence_guard =
                        PersistenceNotifierGuard::optionally_notify_skipping_background_events(
                                self, || -> NotifyOption { NotifyOption::DoPersist });
                *self.best_block.write().unwrap() = BestBlock::new(block_hash, height);

                self.do_chain_event(Some(height), |channel| channel.best_block_updated(height, header.time, self.chain_hash, &self.node_signer, &self.default_configuration, &self.logger));

                macro_rules! max_time {
                        ($timestamp: expr) => {
                                loop {
                                        // Update $timestamp to be the max of its current value and the block
                                        // timestamp. This should keep us close to the current time without relying on
                                        // having an explicit local time source.
                                        // Just in case we end up in a race, we loop until we either successfully
                                        // update $timestamp or decide we don't need to.
                                        let old_serial = $timestamp.load(Ordering::Acquire);
                                        if old_serial >= header.time as usize { break; }
                                        if $timestamp.compare_exchange(old_serial, header.time as usize, Ordering::AcqRel, Ordering::Relaxed).is_ok() {
                                                break;
                                        }
                                }
                        }
                }
                max_time!(self.highest_seen_timestamp);
                let mut payment_secrets = self.pending_inbound_payments.lock().unwrap();
                payment_secrets.retain(|_, inbound_payment| {
                        inbound_payment.expiry_time > header.time as u64
                });
        }

        fn get_relevant_txids(&self) -> Vec<(Txid, u32, Option<BlockHash>)> {
                let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
                for (_cp_id, peer_state_mutex) in self.per_peer_state.read().unwrap().iter() {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        for chan in peer_state.channel_by_id.values().filter_map(|phase| if let ChannelPhase::Funded(chan) = phase { Some(chan) } else { None }) {
                                let txid_opt = chan.context.get_funding_txo();
                                let height_opt = chan.context.get_funding_tx_confirmation_height();
                                let hash_opt = chan.context.get_funding_tx_confirmed_in();
                                if let (Some(funding_txo), Some(conf_height), Some(block_hash)) = (txid_opt, height_opt, hash_opt) {
                                        res.push((funding_txo.txid, conf_height, Some(block_hash)));
                                }
                        }
                }
                res
        }

        fn transaction_unconfirmed(&self, txid: &Txid) {
                let _persistence_guard =
                        PersistenceNotifierGuard::optionally_notify_skipping_background_events(
                                self, || -> NotifyOption { NotifyOption::DoPersist });
                self.do_chain_event(None, |channel| {
                        if let Some(funding_txo) = channel.context.get_funding_txo() {
                                if funding_txo.txid == *txid {
                                        channel.funding_transaction_unconfirmed(&self.logger).map(|()| (None, Vec::new(), None))
                                } else { Ok((None, Vec::new(), None)) }
                        } else { Ok((None, Vec::new(), None)) }
                });
        }
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        /// Calls a function which handles an on-chain event (blocks dis/connected, transactions
        /// un/confirmed, etc) on each channel, handling any resulting errors or messages generated by
        /// the function.
        fn do_chain_event<FN: Fn(&mut Channel<SP>) -> Result<(Option<msgs::ChannelReady>, Vec<(HTLCSource, PaymentHash)>, Option<msgs::AnnouncementSignatures>), ClosureReason>>
                        (&self, height_opt: Option<u32>, f: FN) {
                // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
                // during initialization prior to the chain_monitor being fully configured in some cases.
                // See the docs for `ChannelManagerReadArgs` for more.

                let mut failed_channels = Vec::new();
                let mut timed_out_htlcs = Vec::new();
                {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                let pending_msg_events = &mut peer_state.pending_msg_events;
                                peer_state.channel_by_id.retain(|_, phase| {
                                        match phase {
                                                // Retain unfunded channels.
                                                ChannelPhase::UnfundedOutboundV1(_) | ChannelPhase::UnfundedInboundV1(_) => true,
                                                ChannelPhase::Funded(channel) => {
                                                        let res = f(channel);
                                                        if let Ok((channel_ready_opt, mut timed_out_pending_htlcs, announcement_sigs)) = res {
                                                                for (source, payment_hash) in timed_out_pending_htlcs.drain(..) {
                                                                        let (failure_code, data) = self.get_htlc_inbound_temp_fail_err_and_data(0x1000|14 /* expiry_too_soon */, &channel);
                                                                        timed_out_htlcs.push((source, payment_hash, HTLCFailReason::reason(failure_code, data),
                                                                                HTLCDestination::NextHopChannel { node_id: Some(channel.context.get_counterparty_node_id()), channel_id: channel.context.channel_id() }));
                                                                }
                                                                if let Some(channel_ready) = channel_ready_opt {
                                                                        send_channel_ready!(self, pending_msg_events, channel, channel_ready);
                                                                        if channel.context.is_usable() {
                                                                                log_trace!(self.logger, "Sending channel_ready with private initial channel_update for our counterparty on channel {}", channel.context.channel_id());
                                                                                if let Ok(msg) = self.get_channel_update_for_unicast(channel) {
                                                                                        pending_msg_events.push(events::MessageSendEvent::SendChannelUpdate {
                                                                                                node_id: channel.context.get_counterparty_node_id(),
                                                                                                msg,
                                                                                        });
                                                                                }
                                                                        } else {
                                                                                log_trace!(self.logger, "Sending channel_ready WITHOUT channel_update for {}", channel.context.channel_id());
                                                                        }
                                                                }

                                                                {
                                                                        let mut pending_events = self.pending_events.lock().unwrap();
                                                                        emit_channel_ready_event!(pending_events, channel);
                                                                }

                                                                if let Some(announcement_sigs) = announcement_sigs {
                                                                        log_trace!(self.logger, "Sending announcement_signatures for channel {}", channel.context.channel_id());
                                                                        pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                                                node_id: channel.context.get_counterparty_node_id(),
                                                                                msg: announcement_sigs,
                                                                        });
                                                                        if let Some(height) = height_opt {
                                                                                if let Some(announcement) = channel.get_signed_channel_announcement(&self.node_signer, self.chain_hash, height, &self.default_configuration) {
                                                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelAnnouncement {
                                                                                                msg: announcement,
                                                                                                // Note that announcement_signatures fails if the channel cannot be announced,
                                                                                                // so get_channel_update_for_broadcast will never fail by the time we get here.
                                                                                                update_msg: Some(self.get_channel_update_for_broadcast(channel).unwrap()),
                                                                                        });
                                                                                }
                                                                        }
                                                                }
                                                                if channel.is_our_channel_ready() {
                                                                        if let Some(real_scid) = channel.context.get_short_channel_id() {
                                                                                // If we sent a 0conf channel_ready, and now have an SCID, we add it
                                                                                // to the short_to_chan_info map here. Note that we check whether we
                                                                                // can relay using the real SCID at relay-time (i.e.
                                                                                // enforce option_scid_alias then), and if the funding tx is ever
                                                                                // un-confirmed we force-close the channel, ensuring short_to_chan_info
                                                                                // is always consistent.
                                                                                let mut short_to_chan_info = self.short_to_chan_info.write().unwrap();
                                                                                let scid_insert = short_to_chan_info.insert(real_scid, (channel.context.get_counterparty_node_id(), channel.context.channel_id()));
                                                                                assert!(scid_insert.is_none() || scid_insert.unwrap() == (channel.context.get_counterparty_node_id(), channel.context.channel_id()),
                                                                                        "SCIDs should never collide - ensure you weren't behind by a full {} blocks when creating channels",
                                                                                        fake_scid::MAX_SCID_BLOCKS_FROM_NOW);
                                                                        }
                                                                }
                                                        } else if let Err(reason) = res {
                                                                update_maps_on_chan_removal!(self, &channel.context);
                                                                // It looks like our counterparty went on-chain or funding transaction was
                                                                // reorged out of the main chain. Close the channel.
                                                                failed_channels.push(channel.context.force_shutdown(true));
                                                                if let Ok(update) = self.get_channel_update_for_broadcast(&channel) {
                                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                msg: update
                                                                        });
                                                                }
                                                                let reason_message = format!("{}", reason);
                                                                self.issue_channel_close_events(&channel.context, reason);
                                                                pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                                        node_id: channel.context.get_counterparty_node_id(),
                                                                        action: msgs::ErrorAction::DisconnectPeer {
                                                                                msg: Some(msgs::ErrorMessage {
                                                                                        channel_id: channel.context.channel_id(),
                                                                                        data: reason_message,
                                                                                })
                                                                        },
                                                                });
                                                                return false;
                                                        }
                                                        true
                                                }
                                        }
                                });
                        }
                }

                if let Some(height) = height_opt {
                        self.claimable_payments.lock().unwrap().claimable_payments.retain(|payment_hash, payment| {
                                payment.htlcs.retain(|htlc| {
                                        // If height is approaching the number of blocks we think it takes us to get
                                        // our commitment transaction confirmed before the HTLC expires, plus the
                                        // number of blocks we generally consider it to take to do a commitment update,
                                        // just give up on it and fail the HTLC.
                                        if height >= htlc.cltv_expiry - HTLC_FAIL_BACK_BUFFER {
                                                let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
                                                htlc_msat_height_data.extend_from_slice(&height.to_be_bytes());

                                                timed_out_htlcs.push((HTLCSource::PreviousHopData(htlc.prev_hop.clone()), payment_hash.clone(),
                                                        HTLCFailReason::reason(0x4000 | 15, htlc_msat_height_data),
                                                        HTLCDestination::FailedPayment { payment_hash: payment_hash.clone() }));
                                                false
                                        } else { true }
                                });
                                !payment.htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
                        });

                        let mut intercepted_htlcs = self.pending_intercepted_htlcs.lock().unwrap();
                        intercepted_htlcs.retain(|_, htlc| {
                                if height >= htlc.forward_info.outgoing_cltv_value - HTLC_FAIL_BACK_BUFFER {
                                        let prev_hop_data = HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                                short_channel_id: htlc.prev_short_channel_id,
                                                user_channel_id: Some(htlc.prev_user_channel_id),
                                                htlc_id: htlc.prev_htlc_id,
                                                incoming_packet_shared_secret: htlc.forward_info.incoming_shared_secret,
                                                phantom_shared_secret: None,
                                                outpoint: htlc.prev_funding_outpoint,
                                        });

                                        let requested_forward_scid /* intercept scid */ = match htlc.forward_info.routing {
                                                PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
                                                _ => unreachable!(),
                                        };
                                        timed_out_htlcs.push((prev_hop_data, htlc.forward_info.payment_hash,
                                                        HTLCFailReason::from_failure_code(0x2000 | 2),
                                                        HTLCDestination::InvalidForward { requested_forward_scid }));
                                        log_trace!(self.logger, "Timing out intercepted HTLC with requested forward scid {}", requested_forward_scid);
                                        false
                                } else { true }
                        });
                }

                self.handle_init_event_channel_failures(failed_channels);

                for (source, payment_hash, reason, destination) in timed_out_htlcs.drain(..) {
                        self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, destination);
                }
        }

        /// Gets a [`Future`] that completes when this [`ChannelManager`] may need to be persisted or
        /// may have events that need processing.
        ///
        /// In order to check if this [`ChannelManager`] needs persisting, call
        /// [`Self::get_and_clear_needs_persistence`].
        ///
        /// Note that callbacks registered on the [`Future`] MUST NOT call back into this
        /// [`ChannelManager`] and should instead register actions to be taken later.
        pub fn get_event_or_persistence_needed_future(&self) -> Future {
                self.event_persist_notifier.get_future()
        }

        /// Returns true if this [`ChannelManager`] needs to be persisted.
        pub fn get_and_clear_needs_persistence(&self) -> bool {
                self.needs_persist_flag.swap(false, Ordering::AcqRel)
        }

        #[cfg(any(test, feature = "_test_utils"))]
        pub fn get_event_or_persist_condvar_value(&self) -> bool {
                self.event_persist_notifier.notify_pending()
        }

        /// Gets the latest best block which was connected either via the [`chain::Listen`] or
        /// [`chain::Confirm`] interfaces.
        pub fn current_best_block(&self) -> BestBlock {
                self.best_block.read().unwrap().clone()
        }

        /// Fetches the set of [`NodeFeatures`] flags that are provided by or required by
        /// [`ChannelManager`].
        pub fn node_features(&self) -> NodeFeatures {
                provided_node_features(&self.default_configuration)
        }

        /// Fetches the set of [`Bolt11InvoiceFeatures`] flags that are provided by or required by
        /// [`ChannelManager`].
        ///
        /// Note that the invoice feature flags can vary depending on if the invoice is a "phantom invoice"
        /// or not. Thus, this method is not public.
        #[cfg(any(feature = "_test_utils", test))]
        pub fn bolt11_invoice_features(&self) -> Bolt11InvoiceFeatures {
                provided_bolt11_invoice_features(&self.default_configuration)
        }

        /// Fetches the set of [`Bolt12InvoiceFeatures`] flags that are provided by or required by
        /// [`ChannelManager`].
        fn bolt12_invoice_features(&self) -> Bolt12InvoiceFeatures {
                provided_bolt12_invoice_features(&self.default_configuration)
        }

        /// Fetches the set of [`ChannelFeatures`] flags that are provided by or required by
        /// [`ChannelManager`].
        pub fn channel_features(&self) -> ChannelFeatures {
                provided_channel_features(&self.default_configuration)
        }

        /// Fetches the set of [`ChannelTypeFeatures`] flags that are provided by or required by
        /// [`ChannelManager`].
        pub fn channel_type_features(&self) -> ChannelTypeFeatures {
                provided_channel_type_features(&self.default_configuration)
        }

        /// Fetches the set of [`InitFeatures`] flags that are provided by or required by
        /// [`ChannelManager`].
        pub fn init_features(&self) -> InitFeatures {
                provided_init_features(&self.default_configuration)
        }
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>
        ChannelMessageHandler for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        fn handle_open_channel(&self, counterparty_node_id: &PublicKey, msg: &msgs::OpenChannel) {
                // Note that we never need to persist the updated ChannelManager for an inbound
                // open_channel message - pre-funded channels are never written so there should be no
                // change to the contents.
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let res = self.internal_open_channel(counterparty_node_id, msg);
                        let persist = match &res {
                                Err(e) if e.closes_channel() => {
                                        debug_assert!(false, "We shouldn't close a new channel");
                                        NotifyOption::DoPersist
                                },
                                _ => NotifyOption::SkipPersistHandleEvents,
                        };
                        let _ = handle_error!(self, res, *counterparty_node_id);
                        persist
                });
        }

        fn handle_open_channel_v2(&self, counterparty_node_id: &PublicKey, msg: &msgs::OpenChannelV2) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.temporary_channel_id.clone())), *counterparty_node_id);
        }

        fn handle_accept_channel(&self, counterparty_node_id: &PublicKey, msg: &msgs::AcceptChannel) {
                // Note that we never need to persist the updated ChannelManager for an inbound
                // accept_channel message - pre-funded channels are never written so there should be no
                // change to the contents.
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let _ = handle_error!(self, self.internal_accept_channel(counterparty_node_id, msg), *counterparty_node_id);
                        NotifyOption::SkipPersistHandleEvents
                });
        }

        fn handle_accept_channel_v2(&self, counterparty_node_id: &PublicKey, msg: &msgs::AcceptChannelV2) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.temporary_channel_id.clone())), *counterparty_node_id);
        }

        fn handle_funding_created(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingCreated) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_funding_created(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_funding_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingSigned) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_funding_signed(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_channel_ready(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReady) {
                // Note that we never need to persist the updated ChannelManager for an inbound
                // channel_ready message - while the channel's state will change, any channel_ready message
                // will ultimately be re-sent on startup and the `ChannelMonitor` won't be updated so we
                // will not force-close the channel on startup.
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let res = self.internal_channel_ready(counterparty_node_id, msg);
                        let persist = match &res {
                                Err(e) if e.closes_channel() => NotifyOption::DoPersist,
                                _ => NotifyOption::SkipPersistHandleEvents,
                        };
                        let _ = handle_error!(self, res, *counterparty_node_id);
                        persist
                });
        }

        fn handle_stfu(&self, counterparty_node_id: &PublicKey, msg: &msgs::Stfu) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Quiescence not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_splice(&self, counterparty_node_id: &PublicKey, msg: &msgs::Splice) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Splicing not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_splice_ack(&self, counterparty_node_id: &PublicKey, msg: &msgs::SpliceAck) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Splicing not supported (splice_ack)".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_splice_locked(&self, counterparty_node_id: &PublicKey, msg: &msgs::SpliceLocked) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Splicing not supported (splice_locked)".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_shutdown(&self, counterparty_node_id: &PublicKey, msg: &msgs::Shutdown) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_shutdown(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_closing_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::ClosingSigned) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_closing_signed(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_update_add_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateAddHTLC) {
                // Note that we never need to persist the updated ChannelManager for an inbound
                // update_add_htlc message - the message itself doesn't change our channel state only the
                // `commitment_signed` message afterwards will.
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let res = self.internal_update_add_htlc(counterparty_node_id, msg);
                        let persist = match &res {
                                Err(e) if e.closes_channel() => NotifyOption::DoPersist,
                                Err(_) => NotifyOption::SkipPersistHandleEvents,
                                Ok(()) => NotifyOption::SkipPersistNoEvents,
                        };
                        let _ = handle_error!(self, res, *counterparty_node_id);
                        persist
                });
        }

        fn handle_update_fulfill_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_update_fulfill_htlc(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_update_fail_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) {
                // Note that we never need to persist the updated ChannelManager for an inbound
                // update_fail_htlc message - the message itself doesn't change our channel state only the
                // `commitment_signed` message afterwards will.
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let res = self.internal_update_fail_htlc(counterparty_node_id, msg);
                        let persist = match &res {
                                Err(e) if e.closes_channel() => NotifyOption::DoPersist,
                                Err(_) => NotifyOption::SkipPersistHandleEvents,
                                Ok(()) => NotifyOption::SkipPersistNoEvents,
                        };
                        let _ = handle_error!(self, res, *counterparty_node_id);
                        persist
                });
        }

        fn handle_update_fail_malformed_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) {
                // Note that we never need to persist the updated ChannelManager for an inbound
                // update_fail_malformed_htlc message - the message itself doesn't change our channel state
                // only the `commitment_signed` message afterwards will.
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let res = self.internal_update_fail_malformed_htlc(counterparty_node_id, msg);
                        let persist = match &res {
                                Err(e) if e.closes_channel() => NotifyOption::DoPersist,
                                Err(_) => NotifyOption::SkipPersistHandleEvents,
                                Ok(()) => NotifyOption::SkipPersistNoEvents,
                        };
                        let _ = handle_error!(self, res, *counterparty_node_id);
                        persist
                });
        }

        fn handle_commitment_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::CommitmentSigned) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_commitment_signed(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_revoke_and_ack(&self, counterparty_node_id: &PublicKey, msg: &msgs::RevokeAndACK) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_revoke_and_ack(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_update_fee(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFee) {
                // Note that we never need to persist the updated ChannelManager for an inbound
                // update_fee message - the message itself doesn't change our channel state only the
                // `commitment_signed` message afterwards will.
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let res = self.internal_update_fee(counterparty_node_id, msg);
                        let persist = match &res {
                                Err(e) if e.closes_channel() => NotifyOption::DoPersist,
                                Err(_) => NotifyOption::SkipPersistHandleEvents,
                                Ok(()) => NotifyOption::SkipPersistNoEvents,
                        };
                        let _ = handle_error!(self, res, *counterparty_node_id);
                        persist
                });
        }

        fn handle_announcement_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                let _ = handle_error!(self, self.internal_announcement_signatures(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_channel_update(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelUpdate) {
                PersistenceNotifierGuard::optionally_notify(self, || {
                        if let Ok(persist) = handle_error!(self, self.internal_channel_update(counterparty_node_id, msg), *counterparty_node_id) {
                                persist
                        } else {
                                NotifyOption::DoPersist
                        }
                });
        }

        fn handle_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) {
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(self, || {
                        let res = self.internal_channel_reestablish(counterparty_node_id, msg);
                        let persist = match &res {
                                Err(e) if e.closes_channel() => NotifyOption::DoPersist,
                                Err(_) => NotifyOption::SkipPersistHandleEvents,
                                Ok(persist) => *persist,
                        };
                        let _ = handle_error!(self, res, *counterparty_node_id);
                        persist
                });
        }

        fn peer_disconnected(&self, counterparty_node_id: &PublicKey) {
                let _persistence_guard = PersistenceNotifierGuard::optionally_notify(
                        self, || NotifyOption::SkipPersistHandleEvents);
                let mut failed_channels = Vec::new();
                let mut per_peer_state = self.per_peer_state.write().unwrap();
                let remove_peer = {
                        log_debug!(self.logger, "Marking channels with {} disconnected and generating channel_updates.",
                                log_pubkey!(counterparty_node_id));
                        if let Some(peer_state_mutex) = per_peer_state.get(counterparty_node_id) {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                let pending_msg_events = &mut peer_state.pending_msg_events;
                                peer_state.channel_by_id.retain(|_, phase| {
                                        let context = match phase {
                                                ChannelPhase::Funded(chan) => {
                                                        if chan.remove_uncommitted_htlcs_and_mark_paused(&self.logger).is_ok() {
                                                                // We only retain funded channels that are not shutdown.
                                                                return true;
                                                        }
                                                        &mut chan.context
                                                },
                                                // Unfunded channels will always be removed.
                                                ChannelPhase::UnfundedOutboundV1(chan) => {
                                                        &mut chan.context
                                                },
                                                ChannelPhase::UnfundedInboundV1(chan) => {
                                                        &mut chan.context
                                                },
                                        };
                                        // Clean up for removal.
                                        update_maps_on_chan_removal!(self, &context);
                                        self.issue_channel_close_events(&context, ClosureReason::DisconnectedPeer);
                                        failed_channels.push(context.force_shutdown(false));
                                        false
                                });
                                // Note that we don't bother generating any events for pre-accept channels -
                                // they're not considered "channels" yet from the PoV of our events interface.
                                peer_state.inbound_channel_request_by_id.clear();
                                pending_msg_events.retain(|msg| {
                                        match msg {
                                                // V1 Channel Establishment
                                                &events::MessageSendEvent::SendAcceptChannel { .. } => false,
                                                &events::MessageSendEvent::SendOpenChannel { .. } => false,
                                                &events::MessageSendEvent::SendFundingCreated { .. } => false,
                                                &events::MessageSendEvent::SendFundingSigned { .. } => false,
                                                // V2 Channel Establishment
                                                &events::MessageSendEvent::SendAcceptChannelV2 { .. } => false,
                                                &events::MessageSendEvent::SendOpenChannelV2 { .. } => false,
                                                // Common Channel Establishment
                                                &events::MessageSendEvent::SendChannelReady { .. } => false,
                                                &events::MessageSendEvent::SendAnnouncementSignatures { .. } => false,
                                                // Quiescence
                                                &events::MessageSendEvent::SendStfu { .. } => false,
                                                // Splicing
                                                &events::MessageSendEvent::SendSplice { .. } => false,
                                                &events::MessageSendEvent::SendSpliceAck { .. } => false,
                                                &events::MessageSendEvent::SendSpliceLocked { .. } => false,
                                                // Interactive Transaction Construction
                                                &events::MessageSendEvent::SendTxAddInput { .. } => false,
                                                &events::MessageSendEvent::SendTxAddOutput { .. } => false,
                                                &events::MessageSendEvent::SendTxRemoveInput { .. } => false,
                                                &events::MessageSendEvent::SendTxRemoveOutput { .. } => false,
                                                &events::MessageSendEvent::SendTxComplete { .. } => false,
                                                &events::MessageSendEvent::SendTxSignatures { .. } => false,
                                                &events::MessageSendEvent::SendTxInitRbf { .. } => false,
                                                &events::MessageSendEvent::SendTxAckRbf { .. } => false,
                                                &events::MessageSendEvent::SendTxAbort { .. } => false,
                                                // Channel Operations
                                                &events::MessageSendEvent::UpdateHTLCs { .. } => false,
                                                &events::MessageSendEvent::SendRevokeAndACK { .. } => false,
                                                &events::MessageSendEvent::SendClosingSigned { .. } => false,
                                                &events::MessageSendEvent::SendShutdown { .. } => false,
                                                &events::MessageSendEvent::SendChannelReestablish { .. } => false,
                                                &events::MessageSendEvent::HandleError { .. } => false,
                                                // Gossip
                                                &events::MessageSendEvent::SendChannelAnnouncement { .. } => false,
                                                &events::MessageSendEvent::BroadcastChannelAnnouncement { .. } => true,
                                                &events::MessageSendEvent::BroadcastChannelUpdate { .. } => true,
                                                &events::MessageSendEvent::BroadcastNodeAnnouncement { .. } => true,
                                                &events::MessageSendEvent::SendChannelUpdate { .. } => false,
                                                &events::MessageSendEvent::SendChannelRangeQuery { .. } => false,
                                                &events::MessageSendEvent::SendShortIdsQuery { .. } => false,
                                                &events::MessageSendEvent::SendReplyChannelRange { .. } => false,
                                                &events::MessageSendEvent::SendGossipTimestampFilter { .. } => false,
                                        }
                                });
                                debug_assert!(peer_state.is_connected, "A disconnected peer cannot disconnect");
                                peer_state.is_connected = false;
                                peer_state.ok_to_remove(true)
                        } else { debug_assert!(false, "Unconnected peer disconnected"); true }
                };
                if remove_peer {
                        per_peer_state.remove(counterparty_node_id);
                }
                mem::drop(per_peer_state);

                for failure in failed_channels.drain(..) {
                        self.finish_close_channel(failure);
                }
        }

        fn peer_connected(&self, counterparty_node_id: &PublicKey, init_msg: &msgs::Init, inbound: bool) -> Result<(), ()> {
                if !init_msg.features.supports_static_remote_key() {
                        log_debug!(self.logger, "Peer {} does not support static remote key, disconnecting", log_pubkey!(counterparty_node_id));
                        return Err(());
                }

                let mut res = Ok(());

                PersistenceNotifierGuard::optionally_notify(self, || {
                        // If we have too many peers connected which don't have funded channels, disconnect the
                        // peer immediately (as long as it doesn't have funded channels). If we have a bunch of
                        // unfunded channels taking up space in memory for disconnected peers, we still let new
                        // peers connect, but we'll reject new channels from them.
                        let connected_peers_without_funded_channels = self.peers_without_funded_channels(|node| node.is_connected);
                        let inbound_peer_limited = inbound && connected_peers_without_funded_channels >= MAX_NO_CHANNEL_PEERS;

                        {
                                let mut peer_state_lock = self.per_peer_state.write().unwrap();
                                match peer_state_lock.entry(counterparty_node_id.clone()) {
                                        hash_map::Entry::Vacant(e) => {
                                                if inbound_peer_limited {
                                                        res = Err(());
                                                        return NotifyOption::SkipPersistNoEvents;
                                                }
                                                e.insert(Mutex::new(PeerState {
                                                        channel_by_id: HashMap::new(),
                                                        inbound_channel_request_by_id: HashMap::new(),
                                                        latest_features: init_msg.features.clone(),
                                                        pending_msg_events: Vec::new(),
                                                        in_flight_monitor_updates: BTreeMap::new(),
                                                        monitor_update_blocked_actions: BTreeMap::new(),
                                                        actions_blocking_raa_monitor_updates: BTreeMap::new(),
                                                        is_connected: true,
                                                }));
                                        },
                                        hash_map::Entry::Occupied(e) => {
                                                let mut peer_state = e.get().lock().unwrap();
                                                peer_state.latest_features = init_msg.features.clone();

                                                let best_block_height = self.best_block.read().unwrap().height();
                                                if inbound_peer_limited &&
                                                        Self::unfunded_channel_count(&*peer_state, best_block_height) ==
                                                        peer_state.channel_by_id.len()
                                                {
                                                        res = Err(());
                                                        return NotifyOption::SkipPersistNoEvents;
                                                }

                                                debug_assert!(!peer_state.is_connected, "A peer shouldn't be connected twice");
                                                peer_state.is_connected = true;
                                        },
                                }
                        }

                        log_debug!(self.logger, "Generating channel_reestablish events for {}", log_pubkey!(counterparty_node_id));

                        let per_peer_state = self.per_peer_state.read().unwrap();
                        if let Some(peer_state_mutex) = per_peer_state.get(counterparty_node_id) {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                let pending_msg_events = &mut peer_state.pending_msg_events;

                                peer_state.channel_by_id.iter_mut().filter_map(|(_, phase)|
                                        if let ChannelPhase::Funded(chan) = phase { Some(chan) } else {
                                                // Since unfunded channel maps are cleared upon disconnecting a peer, and they're not persisted
                                                // (so won't be recovered after a crash), they shouldn't exist here and we would never need to
                                                // worry about closing and removing them.
                                                debug_assert!(false);
                                                None
                                        }
                                ).for_each(|chan| {
                                        pending_msg_events.push(events::MessageSendEvent::SendChannelReestablish {
                                                node_id: chan.context.get_counterparty_node_id(),
                                                msg: chan.get_channel_reestablish(&self.logger),
                                        });
                                });
                        }

                        return NotifyOption::SkipPersistHandleEvents;
                        //TODO: Also re-broadcast announcement_signatures
                });
                res
        }

        fn handle_error(&self, counterparty_node_id: &PublicKey, msg: &msgs::ErrorMessage) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);

                match &msg.data as &str {
                        "cannot co-op close channel w/ active htlcs"|
                        "link failed to shutdown" =>
                        {
                                // LND hasn't properly handled shutdown messages ever, and force-closes any time we
                                // send one while HTLCs are still present. The issue is tracked at
                                // https://github.com/lightningnetwork/lnd/issues/6039 and has had multiple patches
                                // to fix it but none so far have managed to land upstream. The issue appears to be
                                // very low priority for the LND team despite being marked "P1".
                                // We're not going to bother handling this in a sensible way, instead simply
                                // repeating the Shutdown message on repeat until morale improves.
                                if !msg.channel_id.is_zero() {
                                        let per_peer_state = self.per_peer_state.read().unwrap();
                                        let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
                                        if peer_state_mutex_opt.is_none() { return; }
                                        let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap();
                                        if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get(&msg.channel_id) {
                                                if let Some(msg) = chan.get_outbound_shutdown() {
                                                        peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                                node_id: *counterparty_node_id,
                                                                msg,
                                                        });
                                                }
                                                peer_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                        node_id: *counterparty_node_id,
                                                        action: msgs::ErrorAction::SendWarningMessage {
                                                                msg: msgs::WarningMessage {
                                                                        channel_id: msg.channel_id,
                                                                        data: "You appear to be exhibiting LND bug 6039, we'll keep sending you shutdown messages until you handle them correctly".to_owned()
                                                                },
                                                                log_level: Level::Trace,
                                                        }
                                                });
                                        }
                                }
                                return;
                        }
                        _ => {}
                }

                if msg.channel_id.is_zero() {
                        let channel_ids: Vec<ChannelId> = {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
                                if peer_state_mutex_opt.is_none() { return; }
                                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                // Note that we don't bother generating any events for pre-accept channels -
                                // they're not considered "channels" yet from the PoV of our events interface.
                                peer_state.inbound_channel_request_by_id.clear();
                                peer_state.channel_by_id.keys().cloned().collect()
                        };
                        for channel_id in channel_ids {
                                // Untrusted messages from peer, we throw away the error if id points to a non-existent channel
                                let _ = self.force_close_channel_with_peer(&channel_id, counterparty_node_id, Some(&msg.data), true);
                        }
                } else {
                        {
                                // First check if we can advance the channel type and try again.
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
                                if peer_state_mutex_opt.is_none() { return; }
                                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                if let Some(ChannelPhase::UnfundedOutboundV1(chan)) = peer_state.channel_by_id.get_mut(&msg.channel_id) {
                                        if let Ok(msg) = chan.maybe_handle_error_without_close(self.chain_hash, &self.fee_estimator) {
                                                peer_state.pending_msg_events.push(events::MessageSendEvent::SendOpenChannel {
                                                        node_id: *counterparty_node_id,
                                                        msg,
                                                });
                                                return;
                                        }
                                }
                        }

                        // Untrusted messages from peer, we throw away the error if id points to a non-existent channel
                        let _ = self.force_close_channel_with_peer(&msg.channel_id, counterparty_node_id, Some(&msg.data), true);
                }
        }

        fn provided_node_features(&self) -> NodeFeatures {
                provided_node_features(&self.default_configuration)
        }

        fn provided_init_features(&self, _their_init_features: &PublicKey) -> InitFeatures {
                provided_init_features(&self.default_configuration)
        }

        fn get_chain_hashes(&self) -> Option<Vec<ChainHash>> {
                Some(vec![self.chain_hash])
        }

        fn handle_tx_add_input(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxAddInput) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_add_output(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxAddOutput) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_remove_input(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxRemoveInput) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_remove_output(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxRemoveOutput) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_complete(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxComplete) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxSignatures) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_init_rbf(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxInitRbf) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_ack_rbf(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxAckRbf) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }

        fn handle_tx_abort(&self, counterparty_node_id: &PublicKey, msg: &msgs::TxAbort) {
                let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
                        "Dual-funded channels not supported".to_owned(),
                         msg.channel_id.clone())), *counterparty_node_id);
        }
}

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>
OffersMessageHandler for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        fn handle_message(&self, message: OffersMessage) -> Option<OffersMessage> {
                let secp_ctx = &self.secp_ctx;
                let expanded_key = &self.inbound_payment_key;

                match message {
                        OffersMessage::InvoiceRequest(invoice_request) => {
                                let amount_msats = match InvoiceBuilder::<DerivedSigningPubkey>::amount_msats(
                                        &invoice_request
                                ) {
                                        Ok(amount_msats) => Some(amount_msats),
                                        Err(error) => return Some(OffersMessage::InvoiceError(error.into())),
                                };
                                let invoice_request = match invoice_request.verify(expanded_key, secp_ctx) {
                                        Ok(invoice_request) => invoice_request,
                                        Err(()) => {
                                                let error = Bolt12SemanticError::InvalidMetadata;
                                                return Some(OffersMessage::InvoiceError(error.into()));
                                        },
                                };
                                let relative_expiry = DEFAULT_RELATIVE_EXPIRY.as_secs() as u32;

                                match self.create_inbound_payment(amount_msats, relative_expiry, None) {
                                        Ok((payment_hash, payment_secret)) if invoice_request.keys.is_some() => {
                                                let payment_paths = vec![
                                                        self.create_one_hop_blinded_payment_path(payment_secret),
                                                ];
                                                #[cfg(not(feature = "no-std"))]
                                                let builder = invoice_request.respond_using_derived_keys(
                                                        payment_paths, payment_hash
                                                );
                                                #[cfg(feature = "no-std")]
                                                let created_at = Duration::from_secs(
                                                        self.highest_seen_timestamp.load(Ordering::Acquire) as u64
                                                );
                                                #[cfg(feature = "no-std")]
                                                let builder = invoice_request.respond_using_derived_keys_no_std(
                                                        payment_paths, payment_hash, created_at
                                                );
                                                match builder.and_then(|b| b.allow_mpp().build_and_sign(secp_ctx)) {
                                                        Ok(invoice) => Some(OffersMessage::Invoice(invoice)),
                                                        Err(error) => Some(OffersMessage::InvoiceError(error.into())),
                                                }
                                        },
                                        Ok((payment_hash, payment_secret)) => {
                                                let payment_paths = vec![
                                                        self.create_one_hop_blinded_payment_path(payment_secret),
                                                ];
                                                #[cfg(not(feature = "no-std"))]
                                                let builder = invoice_request.respond_with(payment_paths, payment_hash);
                                                #[cfg(feature = "no-std")]
                                                let created_at = Duration::from_secs(
                                                        self.highest_seen_timestamp.load(Ordering::Acquire) as u64
                                                );
                                                #[cfg(feature = "no-std")]
                                                let builder = invoice_request.respond_with_no_std(
                                                        payment_paths, payment_hash, created_at
                                                );
                                                let response = builder.and_then(|builder| builder.allow_mpp().build())
                                                        .map_err(|e| OffersMessage::InvoiceError(e.into()))
                                                        .and_then(|invoice|
                                                                match invoice.sign(|invoice| self.node_signer.sign_bolt12_invoice(invoice)) {
                                                                        Ok(invoice) => Ok(OffersMessage::Invoice(invoice)),
                                                                        Err(SignError::Signing(())) => Err(OffersMessage::InvoiceError(
                                                                                        InvoiceError::from_string("Failed signing invoice".to_string())
                                                                        )),
                                                                        Err(SignError::Verification(_)) => Err(OffersMessage::InvoiceError(
                                                                                        InvoiceError::from_string("Failed invoice signature verification".to_string())
                                                                        )),
                                                                });
                                                match response {
                                                        Ok(invoice) => Some(invoice),
                                                        Err(error) => Some(error),
                                                }
                                        },
                                        Err(()) => {
                                                Some(OffersMessage::InvoiceError(Bolt12SemanticError::InvalidAmount.into()))
                                        },
                                }
                        },
                        OffersMessage::Invoice(invoice) => {
                                match invoice.verify(expanded_key, secp_ctx) {
                                        Err(()) => {
                                                Some(OffersMessage::InvoiceError(InvoiceError::from_string("Unrecognized invoice".to_owned())))
                                        },
                                        Ok(_) if invoice.invoice_features().requires_unknown_bits_from(&self.bolt12_invoice_features()) => {
                                                Some(OffersMessage::InvoiceError(Bolt12SemanticError::UnknownRequiredFeatures.into()))
                                        },
                                        Ok(payment_id) => {
                                                if let Err(e) = self.send_payment_for_bolt12_invoice(&invoice, payment_id) {
                                                        log_trace!(self.logger, "Failed paying invoice: {:?}", e);
                                                        Some(OffersMessage::InvoiceError(InvoiceError::from_string(format!("{:?}", e))))
                                                } else {
                                                        None
                                                }
                                        },
                                }
                        },
                        OffersMessage::InvoiceError(invoice_error) => {
                                log_trace!(self.logger, "Received invoice_error: {}", invoice_error);
                                None
                        },
                }
        }

        fn release_pending_messages(&self) -> Vec<PendingOnionMessage<OffersMessage>> {
                core::mem::take(&mut self.pending_offers_messages.lock().unwrap())
        }
}

/// Fetches the set of [`NodeFeatures`] flags that are provided by or required by
/// [`ChannelManager`].
pub(crate) fn provided_node_features(config: &UserConfig) -> NodeFeatures {
        let mut node_features = provided_init_features(config).to_context();
        node_features.set_keysend_optional();
        node_features
}

/// Fetches the set of [`Bolt11InvoiceFeatures`] flags that are provided by or required by
/// [`ChannelManager`].
///
/// Note that the invoice feature flags can vary depending on if the invoice is a "phantom invoice"
/// or not. Thus, this method is not public.
#[cfg(any(feature = "_test_utils", test))]
pub(crate) fn provided_bolt11_invoice_features(config: &UserConfig) -> Bolt11InvoiceFeatures {
        provided_init_features(config).to_context()
}

/// Fetches the set of [`Bolt12InvoiceFeatures`] flags that are provided by or required by
/// [`ChannelManager`].
pub(crate) fn provided_bolt12_invoice_features(config: &UserConfig) -> Bolt12InvoiceFeatures {
        provided_init_features(config).to_context()
}

/// Fetches the set of [`ChannelFeatures`] flags that are provided by or required by
/// [`ChannelManager`].
pub(crate) fn provided_channel_features(config: &UserConfig) -> ChannelFeatures {
        provided_init_features(config).to_context()
}

/// Fetches the set of [`ChannelTypeFeatures`] flags that are provided by or required by
/// [`ChannelManager`].
pub(crate) fn provided_channel_type_features(config: &UserConfig) -> ChannelTypeFeatures {
        ChannelTypeFeatures::from_init(&provided_init_features(config))
}

/// Fetches the set of [`InitFeatures`] flags that are provided by or required by
/// [`ChannelManager`].
pub fn provided_init_features(config: &UserConfig) -> InitFeatures {
        // Note that if new features are added here which other peers may (eventually) require, we
        // should also add the corresponding (optional) bit to the [`ChannelMessageHandler`] impl for
        // [`ErroringMessageHandler`].
        let mut features = InitFeatures::empty();
        features.set_data_loss_protect_required();
        features.set_upfront_shutdown_script_optional();
        features.set_variable_length_onion_required();
        features.set_static_remote_key_required();
        features.set_payment_secret_required();
        features.set_basic_mpp_optional();
        features.set_wumbo_optional();
        features.set_shutdown_any_segwit_optional();
        features.set_channel_type_optional();
        features.set_scid_privacy_optional();
        features.set_zero_conf_optional();
        if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx {
                features.set_anchors_zero_fee_htlc_tx_optional();
        }
        features
}

const SERIALIZATION_VERSION: u8 = 1;
const MIN_SERIALIZATION_VERSION: u8 = 1;

impl_writeable_tlv_based!(CounterpartyForwardingInfo, {
        (2, fee_base_msat, required),
        (4, fee_proportional_millionths, required),
        (6, cltv_expiry_delta, required),
});

impl_writeable_tlv_based!(ChannelCounterparty, {
        (2, node_id, required),
        (4, features, required),
        (6, unspendable_punishment_reserve, required),
        (8, forwarding_info, option),
        (9, outbound_htlc_minimum_msat, option),
        (11, outbound_htlc_maximum_msat, option),
});

impl Writeable for ChannelDetails {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                // `user_channel_id` used to be a single u64 value. In order to remain backwards compatible with
                // versions prior to 0.0.113, the u128 is serialized as two separate u64 values.
                let user_channel_id_low = self.user_channel_id as u64;
                let user_channel_id_high_opt = Some((self.user_channel_id >> 64) as u64);
                write_tlv_fields!(writer, {
                        (1, self.inbound_scid_alias, option),
                        (2, self.channel_id, required),
                        (3, self.channel_type, option),
                        (4, self.counterparty, required),
                        (5, self.outbound_scid_alias, option),
                        (6, self.funding_txo, option),
                        (7, self.config, option),
                        (8, self.short_channel_id, option),
                        (9, self.confirmations, option),
                        (10, self.channel_value_satoshis, required),
                        (12, self.unspendable_punishment_reserve, option),
                        (14, user_channel_id_low, required),
                        (16, self.balance_msat, required),
                        (18, self.outbound_capacity_msat, required),
                        (19, self.next_outbound_htlc_limit_msat, required),
                        (20, self.inbound_capacity_msat, required),
                        (21, self.next_outbound_htlc_minimum_msat, required),
                        (22, self.confirmations_required, option),
                        (24, self.force_close_spend_delay, option),
                        (26, self.is_outbound, required),
                        (28, self.is_channel_ready, required),
                        (30, self.is_usable, required),
                        (32, self.is_public, required),
                        (33, self.inbound_htlc_minimum_msat, option),
                        (35, self.inbound_htlc_maximum_msat, option),
                        (37, user_channel_id_high_opt, option),
                        (39, self.feerate_sat_per_1000_weight, option),
                        (41, self.channel_shutdown_state, option),
                });
                Ok(())
        }
}

impl Readable for ChannelDetails {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
                _init_and_read_len_prefixed_tlv_fields!(reader, {
                        (1, inbound_scid_alias, option),
                        (2, channel_id, required),
                        (3, channel_type, option),
                        (4, counterparty, required),
                        (5, outbound_scid_alias, option),
                        (6, funding_txo, option),
                        (7, config, option),
                        (8, short_channel_id, option),
                        (9, confirmations, option),
                        (10, channel_value_satoshis, required),
                        (12, unspendable_punishment_reserve, option),
                        (14, user_channel_id_low, required),
                        (16, balance_msat, required),
                        (18, outbound_capacity_msat, required),
                        // Note that by the time we get past the required read above, outbound_capacity_msat will be
                        // filled in, so we can safely unwrap it here.
                        (19, next_outbound_htlc_limit_msat, (default_value, outbound_capacity_msat.0.unwrap() as u64)),
                        (20, inbound_capacity_msat, required),
                        (21, next_outbound_htlc_minimum_msat, (default_value, 0)),
                        (22, confirmations_required, option),
                        (24, force_close_spend_delay, option),
                        (26, is_outbound, required),
                        (28, is_channel_ready, required),
                        (30, is_usable, required),
                        (32, is_public, required),
                        (33, inbound_htlc_minimum_msat, option),
                        (35, inbound_htlc_maximum_msat, option),
                        (37, user_channel_id_high_opt, option),
                        (39, feerate_sat_per_1000_weight, option),
                        (41, channel_shutdown_state, option),
                });

                // `user_channel_id` used to be a single u64 value. In order to remain backwards compatible with
                // versions prior to 0.0.113, the u128 is serialized as two separate u64 values.
                let user_channel_id_low: u64 = user_channel_id_low.0.unwrap();
                let user_channel_id = user_channel_id_low as u128 +
                        ((user_channel_id_high_opt.unwrap_or(0 as u64) as u128) << 64);

                Ok(Self {
                        inbound_scid_alias,
                        channel_id: channel_id.0.unwrap(),
                        channel_type,
                        counterparty: counterparty.0.unwrap(),
                        outbound_scid_alias,
                        funding_txo,
                        config,
                        short_channel_id,
                        channel_value_satoshis: channel_value_satoshis.0.unwrap(),
                        unspendable_punishment_reserve,
                        user_channel_id,
                        balance_msat: balance_msat.0.unwrap(),
                        outbound_capacity_msat: outbound_capacity_msat.0.unwrap(),
                        next_outbound_htlc_limit_msat: next_outbound_htlc_limit_msat.0.unwrap(),
                        next_outbound_htlc_minimum_msat: next_outbound_htlc_minimum_msat.0.unwrap(),
                        inbound_capacity_msat: inbound_capacity_msat.0.unwrap(),
                        confirmations_required,
                        confirmations,
                        force_close_spend_delay,
                        is_outbound: is_outbound.0.unwrap(),
                        is_channel_ready: is_channel_ready.0.unwrap(),
                        is_usable: is_usable.0.unwrap(),
                        is_public: is_public.0.unwrap(),
                        inbound_htlc_minimum_msat,
                        inbound_htlc_maximum_msat,
                        feerate_sat_per_1000_weight,
                        channel_shutdown_state,
                })
        }
}

impl_writeable_tlv_based!(PhantomRouteHints, {
        (2, channels, required_vec),
        (4, phantom_scid, required),
        (6, real_node_pubkey, required),
});

impl_writeable_tlv_based_enum!(PendingHTLCRouting,
        (0, Forward) => {
                (0, onion_packet, required),
                (2, short_channel_id, required),
        },
        (1, Receive) => {
                (0, payment_data, required),
                (1, phantom_shared_secret, option),
                (2, incoming_cltv_expiry, required),
                (3, payment_metadata, option),
                (5, custom_tlvs, optional_vec),
        },
        (2, ReceiveKeysend) => {
                (0, payment_preimage, required),
                (2, incoming_cltv_expiry, required),
                (3, payment_metadata, option),
                (4, payment_data, option), // Added in 0.0.116
                (5, custom_tlvs, optional_vec),
        },
;);

impl_writeable_tlv_based!(PendingHTLCInfo, {
        (0, routing, required),
        (2, incoming_shared_secret, required),
        (4, payment_hash, required),
        (6, outgoing_amt_msat, required),
        (8, outgoing_cltv_value, required),
        (9, incoming_amt_msat, option),
        (10, skimmed_fee_msat, option),
});


impl Writeable for HTLCFailureMsg {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                match self {
                        HTLCFailureMsg::Relay(msgs::UpdateFailHTLC { channel_id, htlc_id, reason }) => {
                                0u8.write(writer)?;
                                channel_id.write(writer)?;
                                htlc_id.write(writer)?;
                                reason.write(writer)?;
                        },
                        HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
                                channel_id, htlc_id, sha256_of_onion, failure_code
                        }) => {
                                1u8.write(writer)?;
                                channel_id.write(writer)?;
                                htlc_id.write(writer)?;
                                sha256_of_onion.write(writer)?;
                                failure_code.write(writer)?;
                        },
                }
                Ok(())
        }
}

impl Readable for HTLCFailureMsg {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
                let id: u8 = Readable::read(reader)?;
                match id {
                        0 => {
                                Ok(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
                                        channel_id: Readable::read(reader)?,
                                        htlc_id: Readable::read(reader)?,
                                        reason: Readable::read(reader)?,
                                }))
                        },
                        1 => {
                                Ok(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
                                        channel_id: Readable::read(reader)?,
                                        htlc_id: Readable::read(reader)?,
                                        sha256_of_onion: Readable::read(reader)?,
                                        failure_code: Readable::read(reader)?,
                                }))
                        },
                        // In versions prior to 0.0.101, HTLCFailureMsg objects were written with type 0 or 1 but
                        // weren't length-prefixed and thus didn't support reading the TLV stream suffix of the network
                        // messages contained in the variants.
                        // In version 0.0.101, support for reading the variants with these types was added, and
                        // we should migrate to writing these variants when UpdateFailHTLC or
                        // UpdateFailMalformedHTLC get TLV fields.
                        2 => {
                                let length: BigSize = Readable::read(reader)?;
                                let mut s = FixedLengthReader::new(reader, length.0);
                                let res = Readable::read(&mut s)?;
                                s.eat_remaining()?; // Return ShortRead if there's actually not enough bytes
                                Ok(HTLCFailureMsg::Relay(res))
                        },
                        3 => {
                                let length: BigSize = Readable::read(reader)?;
                                let mut s = FixedLengthReader::new(reader, length.0);
                                let res = Readable::read(&mut s)?;
                                s.eat_remaining()?; // Return ShortRead if there's actually not enough bytes
                                Ok(HTLCFailureMsg::Malformed(res))
                        },
                        _ => Err(DecodeError::UnknownRequiredFeature),
                }
        }
}

impl_writeable_tlv_based_enum!(PendingHTLCStatus, ;
        (0, Forward),
        (1, Fail),
);

impl_writeable_tlv_based!(HTLCPreviousHopData, {
        (0, short_channel_id, required),
        (1, phantom_shared_secret, option),
        (2, outpoint, required),
        (4, htlc_id, required),
        (6, incoming_packet_shared_secret, required),
        (7, user_channel_id, option),
});

impl Writeable for ClaimableHTLC {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                let (payment_data, keysend_preimage) = match &self.onion_payload {
                        OnionPayload::Invoice { _legacy_hop_data } => (_legacy_hop_data.as_ref(), None),
                        OnionPayload::Spontaneous(preimage) => (None, Some(preimage)),
                };
                write_tlv_fields!(writer, {
                        (0, self.prev_hop, required),
                        (1, self.total_msat, required),
                        (2, self.value, required),
                        (3, self.sender_intended_value, required),
                        (4, payment_data, option),
                        (5, self.total_value_received, option),
                        (6, self.cltv_expiry, required),
                        (8, keysend_preimage, option),
                        (10, self.counterparty_skimmed_fee_msat, option),
                });
                Ok(())
        }
}

impl Readable for ClaimableHTLC {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
                _init_and_read_len_prefixed_tlv_fields!(reader, {
                        (0, prev_hop, required),
                        (1, total_msat, option),
                        (2, value_ser, required),
                        (3, sender_intended_value, option),
                        (4, payment_data_opt, option),
                        (5, total_value_received, option),
                        (6, cltv_expiry, required),
                        (8, keysend_preimage, option),
                        (10, counterparty_skimmed_fee_msat, option),
                });
                let payment_data: Option<msgs::FinalOnionHopData> = payment_data_opt;
                let value = value_ser.0.unwrap();
                let onion_payload = match keysend_preimage {
                        Some(p) => {
                                if payment_data.is_some() {
                                        return Err(DecodeError::InvalidValue)
                                }
                                if total_msat.is_none() {
                                        total_msat = Some(value);
                                }
                                OnionPayload::Spontaneous(p)
                        },
                        None => {
                                if total_msat.is_none() {
                                        if payment_data.is_none() {
                                                return Err(DecodeError::InvalidValue)
                                        }
                                        total_msat = Some(payment_data.as_ref().unwrap().total_msat);
                                }
                                OnionPayload::Invoice { _legacy_hop_data: payment_data }
                        },
                };
                Ok(Self {
                        prev_hop: prev_hop.0.unwrap(),
                        timer_ticks: 0,
                        value,
                        sender_intended_value: sender_intended_value.unwrap_or(value),
                        total_value_received,
                        total_msat: total_msat.unwrap(),
                        onion_payload,
                        cltv_expiry: cltv_expiry.0.unwrap(),
                        counterparty_skimmed_fee_msat,
                })
        }
}

impl Readable for HTLCSource {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
                let id: u8 = Readable::read(reader)?;
                match id {
                        0 => {
                                let mut session_priv: crate::util::ser::RequiredWrapper<SecretKey> = crate::util::ser::RequiredWrapper(None);
                                let mut first_hop_htlc_msat: u64 = 0;
                                let mut path_hops = Vec::new();
                                let mut payment_id = None;
                                let mut payment_params: Option<PaymentParameters> = None;
                                let mut blinded_tail: Option<BlindedTail> = None;
                                read_tlv_fields!(reader, {
                                        (0, session_priv, required),
                                        (1, payment_id, option),
                                        (2, first_hop_htlc_msat, required),
                                        (4, path_hops, required_vec),
                                        (5, payment_params, (option: ReadableArgs, 0)),
                                        (6, blinded_tail, option),
                                });
                                if payment_id.is_none() {
                                        // For backwards compat, if there was no payment_id written, use the session_priv bytes
                                        // instead.
                                        payment_id = Some(PaymentId(*session_priv.0.unwrap().as_ref()));
                                }
                                let path = Path { hops: path_hops, blinded_tail };
                                if path.hops.len() == 0 {
                                        return Err(DecodeError::InvalidValue);
                                }
                                if let Some(params) = payment_params.as_mut() {
                                        if let Payee::Clear { ref mut final_cltv_expiry_delta, .. } = params.payee {
                                                if final_cltv_expiry_delta == &0 {
                                                        *final_cltv_expiry_delta = path.final_cltv_expiry_delta().ok_or(DecodeError::InvalidValue)?;
                                                }
                                        }
                                }
                                Ok(HTLCSource::OutboundRoute {
                                        session_priv: session_priv.0.unwrap(),
                                        first_hop_htlc_msat,
                                        path,
                                        payment_id: payment_id.unwrap(),
                                })
                        }
                        1 => Ok(HTLCSource::PreviousHopData(Readable::read(reader)?)),
                        _ => Err(DecodeError::UnknownRequiredFeature),
                }
        }
}

impl Writeable for HTLCSource {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), crate::io::Error> {
                match self {
                        HTLCSource::OutboundRoute { ref session_priv, ref first_hop_htlc_msat, ref path, payment_id } => {
                                0u8.write(writer)?;
                                let payment_id_opt = Some(payment_id);
                                write_tlv_fields!(writer, {
                                        (0, session_priv, required),
                                        (1, payment_id_opt, option),
                                        (2, first_hop_htlc_msat, required),
                                        // 3 was previously used to write a PaymentSecret for the payment.
                                        (4, path.hops, required_vec),
                                        (5, None::<PaymentParameters>, option), // payment_params in LDK versions prior to 0.0.115
                                        (6, path.blinded_tail, option),
                                 });
                        }
                        HTLCSource::PreviousHopData(ref field) => {
                                1u8.write(writer)?;
                                field.write(writer)?;
                        }
                }
                Ok(())
        }
}

impl_writeable_tlv_based!(PendingAddHTLCInfo, {
        (0, forward_info, required),
        (1, prev_user_channel_id, (default_value, 0)),
        (2, prev_short_channel_id, required),
        (4, prev_htlc_id, required),
        (6, prev_funding_outpoint, required),
});

impl_writeable_tlv_based_enum!(HTLCForwardInfo,
        (1, FailHTLC) => {
                (0, htlc_id, required),
                (2, err_packet, required),
        };
        (0, AddHTLC)
);

impl_writeable_tlv_based!(PendingInboundPayment, {
        (0, payment_secret, required),
        (2, expiry_time, required),
        (4, user_payment_id, required),
        (6, payment_preimage, required),
        (8, min_value_msat, required),
});

impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> Writeable for ChannelManager<M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                let _consistency_lock = self.total_consistency_lock.write().unwrap();

                write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);

                self.chain_hash.write(writer)?;
                {
                        let best_block = self.best_block.read().unwrap();
                        best_block.height().write(writer)?;
                        best_block.block_hash().write(writer)?;
                }

                let mut serializable_peer_count: u64 = 0;
                {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let mut number_of_funded_channels = 0;
                        for (_, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                if !peer_state.ok_to_remove(false) {
                                        serializable_peer_count += 1;
                                }

                                number_of_funded_channels += peer_state.channel_by_id.iter().filter(
                                        |(_, phase)| if let ChannelPhase::Funded(chan) = phase { chan.context.is_funding_broadcast() } else { false }
                                ).count();
                        }

                        (number_of_funded_channels as u64).write(writer)?;

                        for (_, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                for channel in peer_state.channel_by_id.iter().filter_map(
                                        |(_, phase)| if let ChannelPhase::Funded(channel) = phase {
                                                if channel.context.is_funding_broadcast() { Some(channel) } else { None }
                                        } else { None }
                                ) {
                                        channel.write(writer)?;
                                }
                        }
                }

                {
                        let forward_htlcs = self.forward_htlcs.lock().unwrap();
                        (forward_htlcs.len() as u64).write(writer)?;
                        for (short_channel_id, pending_forwards) in forward_htlcs.iter() {
                                short_channel_id.write(writer)?;
                                (pending_forwards.len() as u64).write(writer)?;
                                for forward in pending_forwards {
                                        forward.write(writer)?;
                                }
                        }
                }

                let per_peer_state = self.per_peer_state.write().unwrap();

                let pending_inbound_payments = self.pending_inbound_payments.lock().unwrap();
                let claimable_payments = self.claimable_payments.lock().unwrap();
                let pending_outbound_payments = self.pending_outbound_payments.pending_outbound_payments.lock().unwrap();

                let mut htlc_purposes: Vec<&events::PaymentPurpose> = Vec::new();
                let mut htlc_onion_fields: Vec<&_> = Vec::new();
                (claimable_payments.claimable_payments.len() as u64).write(writer)?;
                for (payment_hash, payment) in claimable_payments.claimable_payments.iter() {
                        payment_hash.write(writer)?;
                        (payment.htlcs.len() as u64).write(writer)?;
                        for htlc in payment.htlcs.iter() {
                                htlc.write(writer)?;
                        }
                        htlc_purposes.push(&payment.purpose);
                        htlc_onion_fields.push(&payment.onion_fields);
                }

                let mut monitor_update_blocked_actions_per_peer = None;
                let mut peer_states = Vec::new();
                for (_, peer_state_mutex) in per_peer_state.iter() {
                        // Because we're holding the owning `per_peer_state` write lock here there's no chance
                        // of a lockorder violation deadlock - no other thread can be holding any
                        // per_peer_state lock at all.
                        peer_states.push(peer_state_mutex.unsafe_well_ordered_double_lock_self());
                }

                (serializable_peer_count).write(writer)?;
                for ((peer_pubkey, _), peer_state) in per_peer_state.iter().zip(peer_states.iter()) {
                        // Peers which we have no channels to should be dropped once disconnected. As we
                        // disconnect all peers when shutting down and serializing the ChannelManager, we
                        // consider all peers as disconnected here. There's therefore no need write peers with
                        // no channels.
                        if !peer_state.ok_to_remove(false) {
                                peer_pubkey.write(writer)?;
                                peer_state.latest_features.write(writer)?;
                                if !peer_state.monitor_update_blocked_actions.is_empty() {
                                        monitor_update_blocked_actions_per_peer
                                                .get_or_insert_with(Vec::new)
                                                .push((*peer_pubkey, &peer_state.monitor_update_blocked_actions));
                                }
                        }
                }

                let events = self.pending_events.lock().unwrap();
                // LDK versions prior to 0.0.115 don't support post-event actions, thus if there's no
                // actions at all, skip writing the required TLV. Otherwise, pre-0.0.115 versions will
                // refuse to read the new ChannelManager.
                let events_not_backwards_compatible = events.iter().any(|(_, action)| action.is_some());
                if events_not_backwards_compatible {
                        // If we're gonna write a even TLV that will overwrite our events anyway we might as
                        // well save the space and not write any events here.
                        0u64.write(writer)?;
                } else {
                        (events.len() as u64).write(writer)?;
                        for (event, _) in events.iter() {
                                event.write(writer)?;
                        }
                }

                // LDK versions prior to 0.0.116 wrote the `pending_background_events`
                // `MonitorUpdateRegeneratedOnStartup`s here, however there was never a reason to do so -
                // the closing monitor updates were always effectively replayed on startup (either directly
                // by calling `broadcast_latest_holder_commitment_txn` on a `ChannelMonitor` during
                // deserialization or, in 0.0.115, by regenerating the monitor update itself).
                0u64.write(writer)?;

                // Prior to 0.0.111 we tracked node_announcement serials here, however that now happens in
                // `PeerManager`, and thus we simply write the `highest_seen_timestamp` twice, which is
                // likely to be identical.
                (self.highest_seen_timestamp.load(Ordering::Acquire) as u32).write(writer)?;
                (self.highest_seen_timestamp.load(Ordering::Acquire) as u32).write(writer)?;

                (pending_inbound_payments.len() as u64).write(writer)?;
                for (hash, pending_payment) in pending_inbound_payments.iter() {
                        hash.write(writer)?;
                        pending_payment.write(writer)?;
                }

                // For backwards compat, write the session privs and their total length.
                let mut num_pending_outbounds_compat: u64 = 0;
                for (_, outbound) in pending_outbound_payments.iter() {
                        if !outbound.is_fulfilled() && !outbound.abandoned() {
                                num_pending_outbounds_compat += outbound.remaining_parts() as u64;
                        }
                }
                num_pending_outbounds_compat.write(writer)?;
                for (_, outbound) in pending_outbound_payments.iter() {
                        match outbound {
                                PendingOutboundPayment::Legacy { session_privs } |
                                PendingOutboundPayment::Retryable { session_privs, .. } => {
                                        for session_priv in session_privs.iter() {
                                                session_priv.write(writer)?;
                                        }
                                }
                                PendingOutboundPayment::AwaitingInvoice { .. } => {},
                                PendingOutboundPayment::InvoiceReceived { .. } => {},
                                PendingOutboundPayment::Fulfilled { .. } => {},
                                PendingOutboundPayment::Abandoned { .. } => {},
                        }
                }

                // Encode without retry info for 0.0.101 compatibility.
                let mut pending_outbound_payments_no_retry: HashMap<PaymentId, HashSet<[u8; 32]>> = HashMap::new();
                for (id, outbound) in pending_outbound_payments.iter() {
                        match outbound {
                                PendingOutboundPayment::Legacy { session_privs } |
                                PendingOutboundPayment::Retryable { session_privs, .. } => {
                                        pending_outbound_payments_no_retry.insert(*id, session_privs.clone());
                                },
                                _ => {},
                        }
                }

                let mut pending_intercepted_htlcs = None;
                let our_pending_intercepts = self.pending_intercepted_htlcs.lock().unwrap();
                if our_pending_intercepts.len() != 0 {
                        pending_intercepted_htlcs = Some(our_pending_intercepts);
                }

                let mut pending_claiming_payments = Some(&claimable_payments.pending_claiming_payments);
                if pending_claiming_payments.as_ref().unwrap().is_empty() {
                        // LDK versions prior to 0.0.113 do not know how to read the pending claimed payments
                        // map. Thus, if there are no entries we skip writing a TLV for it.
                        pending_claiming_payments = None;
                }

                let mut in_flight_monitor_updates: Option<HashMap<(&PublicKey, &OutPoint), &Vec<ChannelMonitorUpdate>>> = None;
                for ((counterparty_id, _), peer_state) in per_peer_state.iter().zip(peer_states.iter()) {
                        for (funding_outpoint, updates) in peer_state.in_flight_monitor_updates.iter() {
                                if !updates.is_empty() {
                                        if in_flight_monitor_updates.is_none() { in_flight_monitor_updates = Some(HashMap::new()); }
                                        in_flight_monitor_updates.as_mut().unwrap().insert((counterparty_id, funding_outpoint), updates);
                                }
                        }
                }

                write_tlv_fields!(writer, {
                        (1, pending_outbound_payments_no_retry, required),
                        (2, pending_intercepted_htlcs, option),
                        (3, pending_outbound_payments, required),
                        (4, pending_claiming_payments, option),
                        (5, self.our_network_pubkey, required),
                        (6, monitor_update_blocked_actions_per_peer, option),
                        (7, self.fake_scid_rand_bytes, required),
                        (8, if events_not_backwards_compatible { Some(&*events) } else { None }, option),
                        (9, htlc_purposes, required_vec),
                        (10, in_flight_monitor_updates, option),
                        (11, self.probing_cookie_secret, required),
                        (13, htlc_onion_fields, optional_vec),
                });

                Ok(())
        }
}

impl Writeable for VecDeque<(Event, Option<EventCompletionAction>)> {
        fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
                (self.len() as u64).write(w)?;
                for (event, action) in self.iter() {
                        event.write(w)?;
                        action.write(w)?;
                        #[cfg(debug_assertions)] {
                                // Events are MaybeReadable, in some cases indicating that they shouldn't actually
                                // be persisted and are regenerated on restart. However, if such an event has a
                                // post-event-handling action we'll write nothing for the event and would have to
                                // either forget the action or fail on deserialization (which we do below). Thus,
                                // check that the event is sane here.
                                let event_encoded = event.encode();
                                let event_read: Option<Event> =
                                        MaybeReadable::read(&mut &event_encoded[..]).unwrap();
                                if action.is_some() { assert!(event_read.is_some()); }
                        }
                }
                Ok(())
        }
}
impl Readable for VecDeque<(Event, Option<EventCompletionAction>)> {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
                let len: u64 = Readable::read(reader)?;
                const MAX_ALLOC_SIZE: u64 = 1024 * 16;
                let mut events: Self = VecDeque::with_capacity(cmp::min(
                        MAX_ALLOC_SIZE/mem::size_of::<(events::Event, Option<EventCompletionAction>)>() as u64,
                        len) as usize);
                for _ in 0..len {
                        let ev_opt = MaybeReadable::read(reader)?;
                        let action = Readable::read(reader)?;
                        if let Some(ev) = ev_opt {
                                events.push_back((ev, action));
                        } else if action.is_some() {
                                return Err(DecodeError::InvalidValue);
                        }
                }
                Ok(events)
        }
}

impl_writeable_tlv_based_enum!(ChannelShutdownState,
        (0, NotShuttingDown) => {},
        (2, ShutdownInitiated) => {},
        (4, ResolvingHTLCs) => {},
        (6, NegotiatingClosingFee) => {},
        (8, ShutdownComplete) => {}, ;
);

/// Arguments for the creation of a ChannelManager that are not deserialized.
///
/// At a high-level, the process for deserializing a ChannelManager and resuming normal operation
/// is:
/// 1) Deserialize all stored [`ChannelMonitor`]s.
/// 2) Deserialize the [`ChannelManager`] by filling in this struct and calling:
///    `<(BlockHash, ChannelManager)>::read(reader, args)`
///    This may result in closing some channels if the [`ChannelMonitor`] is newer than the stored
///    [`ChannelManager`] state to ensure no loss of funds. Thus, transactions may be broadcasted.
/// 3) If you are not fetching full blocks, register all relevant [`ChannelMonitor`] outpoints the
///    same way you would handle a [`chain::Filter`] call using
///    [`ChannelMonitor::get_outputs_to_watch`] and [`ChannelMonitor::get_funding_txo`].
/// 4) Reconnect blocks on your [`ChannelMonitor`]s.
/// 5) Disconnect/connect blocks on the [`ChannelManager`].
/// 6) Re-persist the [`ChannelMonitor`]s to ensure the latest state is on disk.
///    Note that if you're using a [`ChainMonitor`] for your [`chain::Watch`] implementation, you
///    will likely accomplish this as a side-effect of calling [`chain::Watch::watch_channel`] in
///    the next step.
/// 7) Move the [`ChannelMonitor`]s into your local [`chain::Watch`]. If you're using a
///    [`ChainMonitor`], this is done by calling [`chain::Watch::watch_channel`].
///
/// Note that the ordering of #4-7 is not of importance, however all four must occur before you
/// call any other methods on the newly-deserialized [`ChannelManager`].
///
/// Note that because some channels may be closed during deserialization, it is critical that you
/// always deserialize only the latest version of a ChannelManager and ChannelMonitors available to
/// you. If you deserialize an old ChannelManager (during which force-closure transactions may be
/// broadcast), and then later deserialize a newer version of the same ChannelManager (which will
/// not force-close the same channels but consider them live), you may end up revoking a state for
/// which you've already broadcasted the transaction.
///
/// [`ChainMonitor`]: crate::chain::chainmonitor::ChainMonitor
pub struct ChannelManagerReadArgs<'a, M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        /// A cryptographically secure source of entropy.
        pub entropy_source: ES,

        /// A signer that is able to perform node-scoped cryptographic operations.
        pub node_signer: NS,

        /// The keys provider which will give us relevant keys. Some keys will be loaded during
        /// deserialization and KeysInterface::read_chan_signer will be used to read per-Channel
        /// signing data.
        pub signer_provider: SP,

        /// The fee_estimator for use in the ChannelManager in the future.
        ///
        /// No calls to the FeeEstimator will be made during deserialization.
        pub fee_estimator: F,
        /// The chain::Watch for use in the ChannelManager in the future.
        ///
        /// No calls to the chain::Watch will be made during deserialization. It is assumed that
        /// you have deserialized ChannelMonitors separately and will add them to your
        /// chain::Watch after deserializing this ChannelManager.
        pub chain_monitor: M,

        /// The BroadcasterInterface which will be used in the ChannelManager in the future and may be
        /// used to broadcast the latest local commitment transactions of channels which must be
        /// force-closed during deserialization.
        pub tx_broadcaster: T,
        /// The router which will be used in the ChannelManager in the future for finding routes
        /// on-the-fly for trampoline payments. Absent in private nodes that don't support forwarding.
        ///
        /// No calls to the router will be made during deserialization.
        pub router: R,
        /// The Logger for use in the ChannelManager and which may be used to log information during
        /// deserialization.
        pub logger: L,
        /// Default settings used for new channels. Any existing channels will continue to use the
        /// runtime settings which were stored when the ChannelManager was serialized.
        pub default_config: UserConfig,

        /// A map from channel funding outpoints to ChannelMonitors for those channels (ie
        /// value.context.get_funding_txo() should be the key).
        ///
        /// If a monitor is inconsistent with the channel state during deserialization the channel will
        /// be force-closed using the data in the ChannelMonitor and the channel will be dropped. This
        /// is true for missing channels as well. If there is a monitor missing for which we find
        /// channel data Err(DecodeError::InvalidValue) will be returned.
        ///
        /// In such cases the latest local transactions will be sent to the tx_broadcaster included in
        /// this struct.
        ///
        /// This is not exported to bindings users because we have no HashMap bindings
        pub channel_monitors: HashMap<OutPoint, &'a mut ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>>,
}

impl<'a, M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>
                ChannelManagerReadArgs<'a, M, T, ES, NS, SP, F, R, L>
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        /// Simple utility function to create a ChannelManagerReadArgs which creates the monitor
        /// HashMap for you. This is primarily useful for C bindings where it is not practical to
        /// populate a HashMap directly from C.
        pub fn new(entropy_source: ES, node_signer: NS, signer_provider: SP, fee_estimator: F, chain_monitor: M, tx_broadcaster: T, router: R, logger: L, default_config: UserConfig,
                        mut channel_monitors: Vec<&'a mut ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>>) -> Self {
                Self {
                        entropy_source, node_signer, signer_provider, fee_estimator, chain_monitor, tx_broadcaster, router, logger, default_config,
                        channel_monitors: channel_monitors.drain(..).map(|monitor| { (monitor.get_funding_txo().0, monitor) }).collect()
                }
        }
}

// Implement ReadableArgs for an Arc'd ChannelManager to make it a bit easier to work with the
// SipmleArcChannelManager type:
impl<'a, M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>
        ReadableArgs<ChannelManagerReadArgs<'a, M, T, ES, NS, SP, F, R, L>> for (BlockHash, Arc<ChannelManager<M, T, ES, NS, SP, F, R, L>>)
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        fn read<Reader: io::Read>(reader: &mut Reader, args: ChannelManagerReadArgs<'a, M, T, ES, NS, SP, F, R, L>) -> Result<Self, DecodeError> {
                let (blockhash, chan_manager) = <(BlockHash, ChannelManager<M, T, ES, NS, SP, F, R, L>)>::read(reader, args)?;
                Ok((blockhash, Arc::new(chan_manager)))
        }
}

impl<'a, M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>
        ReadableArgs<ChannelManagerReadArgs<'a, M, T, ES, NS, SP, F, R, L>> for (BlockHash, ChannelManager<M, T, ES, NS, SP, F, R, L>)
where
        M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
        T::Target: BroadcasterInterface,
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
        SP::Target: SignerProvider,
        F::Target: FeeEstimator,
        R::Target: Router,
        L::Target: Logger,
{
        fn read<Reader: io::Read>(reader: &mut Reader, mut args: ChannelManagerReadArgs<'a, M, T, ES, NS, SP, F, R, L>) -> Result<Self, DecodeError> {
                let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);

                let chain_hash: ChainHash = Readable::read(reader)?;
                let best_block_height: u32 = Readable::read(reader)?;
                let best_block_hash: BlockHash = Readable::read(reader)?;

                let mut failed_htlcs = Vec::new();

                let channel_count: u64 = Readable::read(reader)?;
                let mut funding_txo_set = HashSet::with_capacity(cmp::min(channel_count as usize, 128));
                let mut funded_peer_channels: HashMap<PublicKey, HashMap<ChannelId, ChannelPhase<SP>>> = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                let mut id_to_peer = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                let mut short_to_chan_info = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                let mut channel_closures = VecDeque::new();
                let mut close_background_events = Vec::new();
                for _ in 0..channel_count {
                        let mut channel: Channel<SP> = Channel::read(reader, (
                                &args.entropy_source, &args.signer_provider, best_block_height, &provided_channel_type_features(&args.default_config)
                        ))?;
                        let funding_txo = channel.context.get_funding_txo().ok_or(DecodeError::InvalidValue)?;
                        funding_txo_set.insert(funding_txo.clone());
                        if let Some(ref mut monitor) = args.channel_monitors.get_mut(&funding_txo) {
                                if channel.get_cur_holder_commitment_transaction_number() > monitor.get_cur_holder_commitment_number() ||
                                                channel.get_revoked_counterparty_commitment_transaction_number() > monitor.get_min_seen_secret() ||
                                                channel.get_cur_counterparty_commitment_transaction_number() > monitor.get_cur_counterparty_commitment_number() ||
                                                channel.context.get_latest_monitor_update_id() < monitor.get_latest_update_id() {
                                        // But if the channel is behind of the monitor, close the channel:
                                        log_error!(args.logger, "A ChannelManager is stale compared to the current ChannelMonitor!");
                                        log_error!(args.logger, " The channel will be force-closed and the latest commitment transaction from the ChannelMonitor broadcast.");
                                        if channel.context.get_latest_monitor_update_id() < monitor.get_latest_update_id() {
                                                log_error!(args.logger, " The ChannelMonitor for channel {} is at update_id {} but the ChannelManager is at update_id {}.",
                                                        &channel.context.channel_id(), monitor.get_latest_update_id(), channel.context.get_latest_monitor_update_id());
                                        }
                                        if channel.get_cur_holder_commitment_transaction_number() > monitor.get_cur_holder_commitment_number() {
                                                log_error!(args.logger, " The ChannelMonitor for channel {} is at holder commitment number {} but the ChannelManager is at holder commitment number {}.",
                                                        &channel.context.channel_id(), monitor.get_cur_holder_commitment_number(), channel.get_cur_holder_commitment_transaction_number());
                                        }
                                        if channel.get_revoked_counterparty_commitment_transaction_number() > monitor.get_min_seen_secret() {
                                                log_error!(args.logger, " The ChannelMonitor for channel {} is at revoked counterparty transaction number {} but the ChannelManager is at revoked counterparty transaction number {}.",
                                                        &channel.context.channel_id(), monitor.get_min_seen_secret(), channel.get_revoked_counterparty_commitment_transaction_number());
                                        }
                                        if channel.get_cur_counterparty_commitment_transaction_number() > monitor.get_cur_counterparty_commitment_number() {
                                                log_error!(args.logger, " The ChannelMonitor for channel {} is at counterparty commitment transaction number {} but the ChannelManager is at counterparty commitment transaction number {}.",
                                                        &channel.context.channel_id(), monitor.get_cur_counterparty_commitment_number(), channel.get_cur_counterparty_commitment_transaction_number());
                                        }
                                        let mut shutdown_result = channel.context.force_shutdown(true);
                                        if shutdown_result.unbroadcasted_batch_funding_txid.is_some() {
                                                return Err(DecodeError::InvalidValue);
                                        }
                                        if let Some((counterparty_node_id, funding_txo, update)) = shutdown_result.monitor_update {
                                                close_background_events.push(BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
                                                        counterparty_node_id, funding_txo, update
                                                });
                                        }
                                        failed_htlcs.append(&mut shutdown_result.dropped_outbound_htlcs);
                                        channel_closures.push_back((events::Event::ChannelClosed {
                                                channel_id: channel.context.channel_id(),
                                                user_channel_id: channel.context.get_user_id(),
                                                reason: ClosureReason::OutdatedChannelManager,
                                                counterparty_node_id: Some(channel.context.get_counterparty_node_id()),
                                                channel_capacity_sats: Some(channel.context.get_value_satoshis()),
                                        }, None));
                                        for (channel_htlc_source, payment_hash) in channel.inflight_htlc_sources() {
                                                let mut found_htlc = false;
                                                for (monitor_htlc_source, _) in monitor.get_all_current_outbound_htlcs() {
                                                        if *channel_htlc_source == monitor_htlc_source { found_htlc = true; break; }
                                                }
                                                if !found_htlc {
                                                        // If we have some HTLCs in the channel which are not present in the newer
                                                        // ChannelMonitor, they have been removed and should be failed back to
                                                        // ensure we don't forget them entirely. Note that if the missing HTLC(s)
                                                        // were actually claimed we'd have generated and ensured the previous-hop
                                                        // claim update ChannelMonitor updates were persisted prior to persising
                                                        // the ChannelMonitor update for the forward leg, so attempting to fail the
                                                        // backwards leg of the HTLC will simply be rejected.
                                                        log_info!(args.logger,
                                                                "Failing HTLC with hash {} as it is missing in the ChannelMonitor for channel {} but was present in the (stale) ChannelManager",
                                                                &channel.context.channel_id(), &payment_hash);
                                                        failed_htlcs.push((channel_htlc_source.clone(), *payment_hash, channel.context.get_counterparty_node_id(), channel.context.channel_id()));
                                                }
                                        }
                                } else {
                                        log_info!(args.logger, "Successfully loaded channel {} at update_id {} against monitor at update id {}",
                                                &channel.context.channel_id(), channel.context.get_latest_monitor_update_id(),
                                                monitor.get_latest_update_id());
                                        if let Some(short_channel_id) = channel.context.get_short_channel_id() {
                                                short_to_chan_info.insert(short_channel_id, (channel.context.get_counterparty_node_id(), channel.context.channel_id()));
                                        }
                                        if channel.context.is_funding_broadcast() {
                                                id_to_peer.insert(channel.context.channel_id(), channel.context.get_counterparty_node_id());
                                        }
                                        match funded_peer_channels.entry(channel.context.get_counterparty_node_id()) {
                                                hash_map::Entry::Occupied(mut entry) => {
                                                        let by_id_map = entry.get_mut();
                                                        by_id_map.insert(channel.context.channel_id(), ChannelPhase::Funded(channel));
                                                },
                                                hash_map::Entry::Vacant(entry) => {
                                                        let mut by_id_map = HashMap::new();
                                                        by_id_map.insert(channel.context.channel_id(), ChannelPhase::Funded(channel));
                                                        entry.insert(by_id_map);
                                                }
                                        }
                                }
                        } else if channel.is_awaiting_initial_mon_persist() {
                                // If we were persisted and shut down while the initial ChannelMonitor persistence
                                // was in-progress, we never broadcasted the funding transaction and can still
                                // safely discard the channel.
                                let _ = channel.context.force_shutdown(false);
                                channel_closures.push_back((events::Event::ChannelClosed {
                                        channel_id: channel.context.channel_id(),
                                        user_channel_id: channel.context.get_user_id(),
                                        reason: ClosureReason::DisconnectedPeer,
                                        counterparty_node_id: Some(channel.context.get_counterparty_node_id()),
                                        channel_capacity_sats: Some(channel.context.get_value_satoshis()),
                                }, None));
                        } else {
                                log_error!(args.logger, "Missing ChannelMonitor for channel {} needed by ChannelManager.", &channel.context.channel_id());
                                log_error!(args.logger, " The chain::Watch API *requires* that monitors are persisted durably before returning,");
                                log_error!(args.logger, " client applications must ensure that ChannelMonitor data is always available and the latest to avoid funds loss!");
                                log_error!(args.logger, " Without the ChannelMonitor we cannot continue without risking funds.");
                                log_error!(args.logger, " Please ensure the chain::Watch API requirements are met and file a bug report at https://github.com/lightningdevkit/rust-lightning");
                                return Err(DecodeError::InvalidValue);
                        }
                }

                for (funding_txo, _) in args.channel_monitors.iter() {
                        if !funding_txo_set.contains(funding_txo) {
                                log_info!(args.logger, "Queueing monitor update to ensure missing channel {} is force closed",
                                        &funding_txo.to_channel_id());
                                let monitor_update = ChannelMonitorUpdate {
                                        update_id: CLOSED_CHANNEL_UPDATE_ID,
                                        updates: vec![ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast: true }],
                                };
                                close_background_events.push(BackgroundEvent::ClosedMonitorUpdateRegeneratedOnStartup((*funding_txo, monitor_update)));
                        }
                }

                const MAX_ALLOC_SIZE: usize = 1024 * 64;
                let forward_htlcs_count: u64 = Readable::read(reader)?;
                let mut forward_htlcs = HashMap::with_capacity(cmp::min(forward_htlcs_count as usize, 128));
                for _ in 0..forward_htlcs_count {
                        let short_channel_id = Readable::read(reader)?;
                        let pending_forwards_count: u64 = Readable::read(reader)?;
                        let mut pending_forwards = Vec::with_capacity(cmp::min(pending_forwards_count as usize, MAX_ALLOC_SIZE/mem::size_of::<HTLCForwardInfo>()));
                        for _ in 0..pending_forwards_count {
                                pending_forwards.push(Readable::read(reader)?);
                        }
                        forward_htlcs.insert(short_channel_id, pending_forwards);
                }

                let claimable_htlcs_count: u64 = Readable::read(reader)?;
                let mut claimable_htlcs_list = Vec::with_capacity(cmp::min(claimable_htlcs_count as usize, 128));
                for _ in 0..claimable_htlcs_count {
                        let payment_hash = Readable::read(reader)?;
                        let previous_hops_len: u64 = Readable::read(reader)?;
                        let mut previous_hops = Vec::with_capacity(cmp::min(previous_hops_len as usize, MAX_ALLOC_SIZE/mem::size_of::<ClaimableHTLC>()));
                        for _ in 0..previous_hops_len {
                                previous_hops.push(<ClaimableHTLC as Readable>::read(reader)?);
                        }
                        claimable_htlcs_list.push((payment_hash, previous_hops));
                }

                let peer_state_from_chans = |channel_by_id| {
                        PeerState {
                                channel_by_id,
                                inbound_channel_request_by_id: HashMap::new(),
                                latest_features: InitFeatures::empty(),
                                pending_msg_events: Vec::new(),
                                in_flight_monitor_updates: BTreeMap::new(),
                                monitor_update_blocked_actions: BTreeMap::new(),
                                actions_blocking_raa_monitor_updates: BTreeMap::new(),
                                is_connected: false,
                        }
                };

                let peer_count: u64 = Readable::read(reader)?;
                let mut per_peer_state = HashMap::with_capacity(cmp::min(peer_count as usize, MAX_ALLOC_SIZE/mem::size_of::<(PublicKey, Mutex<PeerState<SP>>)>()));
                for _ in 0..peer_count {
                        let peer_pubkey = Readable::read(reader)?;
                        let peer_chans = funded_peer_channels.remove(&peer_pubkey).unwrap_or(HashMap::new());
                        let mut peer_state = peer_state_from_chans(peer_chans);
                        peer_state.latest_features = Readable::read(reader)?;
                        per_peer_state.insert(peer_pubkey, Mutex::new(peer_state));
                }

                let event_count: u64 = Readable::read(reader)?;
                let mut pending_events_read: VecDeque<(events::Event, Option<EventCompletionAction>)> =
                        VecDeque::with_capacity(cmp::min(event_count as usize, MAX_ALLOC_SIZE/mem::size_of::<(events::Event, Option<EventCompletionAction>)>()));
                for _ in 0..event_count {
                        match MaybeReadable::read(reader)? {
                                Some(event) => pending_events_read.push_back((event, None)),
                                None => continue,
                        }
                }

                let background_event_count: u64 = Readable::read(reader)?;
                for _ in 0..background_event_count {
                        match <u8 as Readable>::read(reader)? {
                                0 => {
                                        // LDK versions prior to 0.0.116 wrote pending `MonitorUpdateRegeneratedOnStartup`s here,
                                        // however we really don't (and never did) need them - we regenerate all
                                        // on-startup monitor updates.
                                        let _: OutPoint = Readable::read(reader)?;
                                        let _: ChannelMonitorUpdate = Readable::read(reader)?;
                                }
                                _ => return Err(DecodeError::InvalidValue),
                        }
                }

                let _last_node_announcement_serial: u32 = Readable::read(reader)?; // Only used < 0.0.111
                let highest_seen_timestamp: u32 = Readable::read(reader)?;

                let pending_inbound_payment_count: u64 = Readable::read(reader)?;
                let mut pending_inbound_payments: HashMap<PaymentHash, PendingInboundPayment> = HashMap::with_capacity(cmp::min(pending_inbound_payment_count as usize, MAX_ALLOC_SIZE/(3*32)));
                for _ in 0..pending_inbound_payment_count {
                        if pending_inbound_payments.insert(Readable::read(reader)?, Readable::read(reader)?).is_some() {
                                return Err(DecodeError::InvalidValue);
                        }
                }

                let pending_outbound_payments_count_compat: u64 = Readable::read(reader)?;
                let mut pending_outbound_payments_compat: HashMap<PaymentId, PendingOutboundPayment> =
                        HashMap::with_capacity(cmp::min(pending_outbound_payments_count_compat as usize, MAX_ALLOC_SIZE/32));
                for _ in 0..pending_outbound_payments_count_compat {
                        let session_priv = Readable::read(reader)?;
                        let payment = PendingOutboundPayment::Legacy {
                                session_privs: [session_priv].iter().cloned().collect()
                        };
                        if pending_outbound_payments_compat.insert(PaymentId(session_priv), payment).is_some() {
                                return Err(DecodeError::InvalidValue)
                        };
                }

                // pending_outbound_payments_no_retry is for compatibility with 0.0.101 clients.
                let mut pending_outbound_payments_no_retry: Option<HashMap<PaymentId, HashSet<[u8; 32]>>> = None;
                let mut pending_outbound_payments = None;
                let mut pending_intercepted_htlcs: Option<HashMap<InterceptId, PendingAddHTLCInfo>> = Some(HashMap::new());
                let mut received_network_pubkey: Option<PublicKey> = None;
                let mut fake_scid_rand_bytes: Option<[u8; 32]> = None;
                let mut probing_cookie_secret: Option<[u8; 32]> = None;
                let mut claimable_htlc_purposes = None;
                let mut claimable_htlc_onion_fields = None;
                let mut pending_claiming_payments = Some(HashMap::new());
                let mut monitor_update_blocked_actions_per_peer: Option<Vec<(_, BTreeMap<_, Vec<_>>)>> = Some(Vec::new());
                let mut events_override = None;
                let mut in_flight_monitor_updates: Option<HashMap<(PublicKey, OutPoint), Vec<ChannelMonitorUpdate>>> = None;
                read_tlv_fields!(reader, {
                        (1, pending_outbound_payments_no_retry, option),
                        (2, pending_intercepted_htlcs, option),
                        (3, pending_outbound_payments, option),
                        (4, pending_claiming_payments, option),
                        (5, received_network_pubkey, option),
                        (6, monitor_update_blocked_actions_per_peer, option),
                        (7, fake_scid_rand_bytes, option),
                        (8, events_override, option),
                        (9, claimable_htlc_purposes, optional_vec),
                        (10, in_flight_monitor_updates, option),
                        (11, probing_cookie_secret, option),
                        (13, claimable_htlc_onion_fields, optional_vec),
                });
                if fake_scid_rand_bytes.is_none() {
                        fake_scid_rand_bytes = Some(args.entropy_source.get_secure_random_bytes());
                }

                if probing_cookie_secret.is_none() {
                        probing_cookie_secret = Some(args.entropy_source.get_secure_random_bytes());
                }

                if let Some(events) = events_override {
                        pending_events_read = events;
                }

                if !channel_closures.is_empty() {
                        pending_events_read.append(&mut channel_closures);
                }

                if pending_outbound_payments.is_none() && pending_outbound_payments_no_retry.is_none() {
                        pending_outbound_payments = Some(pending_outbound_payments_compat);
                } else if pending_outbound_payments.is_none() {
                        let mut outbounds = HashMap::new();
                        for (id, session_privs) in pending_outbound_payments_no_retry.unwrap().drain() {
                                outbounds.insert(id, PendingOutboundPayment::Legacy { session_privs });
                        }
                        pending_outbound_payments = Some(outbounds);
                }
                let pending_outbounds = OutboundPayments {
                        pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()),
                        retry_lock: Mutex::new(())
                };

                // We have to replay (or skip, if they were completed after we wrote the `ChannelManager`)
                // each `ChannelMonitorUpdate` in `in_flight_monitor_updates`. After doing so, we have to
                // check that each channel we have isn't newer than the latest `ChannelMonitorUpdate`(s) we
                // replayed, and for each monitor update we have to replay we have to ensure there's a
                // `ChannelMonitor` for it.
                //
                // In order to do so we first walk all of our live channels (so that we can check their
                // state immediately after doing the update replays, when we have the `update_id`s
                // available) and then walk any remaining in-flight updates.
                //
                // Because the actual handling of the in-flight updates is the same, it's macro'ized here:
                let mut pending_background_events = Vec::new();
                macro_rules! handle_in_flight_updates {
                        ($counterparty_node_id: expr, $chan_in_flight_upds: expr, $funding_txo: expr,
                         $monitor: expr, $peer_state: expr, $channel_info_log: expr
                        ) => { {
                                let mut max_in_flight_update_id = 0;
                                $chan_in_flight_upds.retain(|upd| upd.update_id > $monitor.get_latest_update_id());
                                for update in $chan_in_flight_upds.iter() {
                                        log_trace!(args.logger, "Replaying ChannelMonitorUpdate {} for {}channel {}",
                                                update.update_id, $channel_info_log, &$funding_txo.to_channel_id());
                                        max_in_flight_update_id = cmp::max(max_in_flight_update_id, update.update_id);
                                        pending_background_events.push(
                                                BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
                                                        counterparty_node_id: $counterparty_node_id,
                                                        funding_txo: $funding_txo,
                                                        update: update.clone(),
                                                });
                                }
                                if $chan_in_flight_upds.is_empty() {
                                        // We had some updates to apply, but it turns out they had completed before we
                                        // were serialized, we just weren't notified of that. Thus, we may have to run
                                        // the completion actions for any monitor updates, but otherwise are done.
                                        pending_background_events.push(
                                                BackgroundEvent::MonitorUpdatesComplete {
                                                        counterparty_node_id: $counterparty_node_id,
                                                        channel_id: $funding_txo.to_channel_id(),
                                                });
                                }
                                if $peer_state.in_flight_monitor_updates.insert($funding_txo, $chan_in_flight_upds).is_some() {
                                        log_error!(args.logger, "Duplicate in-flight monitor update set for the same channel!");
                                        return Err(DecodeError::InvalidValue);
                                }
                                max_in_flight_update_id
                        } }
                }

                for (counterparty_id, peer_state_mtx) in per_peer_state.iter_mut() {
                        let mut peer_state_lock = peer_state_mtx.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        for phase in peer_state.channel_by_id.values() {
                                if let ChannelPhase::Funded(chan) = phase {
                                        // Channels that were persisted have to be funded, otherwise they should have been
                                        // discarded.
                                        let funding_txo = chan.context.get_funding_txo().ok_or(DecodeError::InvalidValue)?;
                                        let monitor = args.channel_monitors.get(&funding_txo)
                                                .expect("We already checked for monitor presence when loading channels");
                                        let mut max_in_flight_update_id = monitor.get_latest_update_id();
                                        if let Some(in_flight_upds) = &mut in_flight_monitor_updates {
                                                if let Some(mut chan_in_flight_upds) = in_flight_upds.remove(&(*counterparty_id, funding_txo)) {
                                                        max_in_flight_update_id = cmp::max(max_in_flight_update_id,
                                                                handle_in_flight_updates!(*counterparty_id, chan_in_flight_upds,
                                                                        funding_txo, monitor, peer_state, ""));
                                                }
                                        }
                                        if chan.get_latest_unblocked_monitor_update_id() > max_in_flight_update_id {
                                                // If the channel is ahead of the monitor, return InvalidValue:
                                                log_error!(args.logger, "A ChannelMonitor is stale compared to the current ChannelManager! This indicates a potentially-critical violation of the chain::Watch API!");
                                                log_error!(args.logger, " The ChannelMonitor for channel {} is at update_id {} with update_id through {} in-flight",
                                                        chan.context.channel_id(), monitor.get_latest_update_id(), max_in_flight_update_id);
                                                log_error!(args.logger, " but the ChannelManager is at update_id {}.", chan.get_latest_unblocked_monitor_update_id());
                                                log_error!(args.logger, " The chain::Watch API *requires* that monitors are persisted durably before returning,");
                                                log_error!(args.logger, " client applications must ensure that ChannelMonitor data is always available and the latest to avoid funds loss!");
                                                log_error!(args.logger, " Without the latest ChannelMonitor we cannot continue without risking funds.");
                                                log_error!(args.logger, " Please ensure the chain::Watch API requirements are met and file a bug report at https://github.com/lightningdevkit/rust-lightning");
                                                return Err(DecodeError::InvalidValue);
                                        }
                                } else {
                                        // We shouldn't have persisted (or read) any unfunded channel types so none should have been
                                        // created in this `channel_by_id` map.
                                        debug_assert!(false);
                                        return Err(DecodeError::InvalidValue);
                                }
                        }
                }

                if let Some(in_flight_upds) = in_flight_monitor_updates {
                        for ((counterparty_id, funding_txo), mut chan_in_flight_updates) in in_flight_upds {
                                if let Some(monitor) = args.channel_monitors.get(&funding_txo) {
                                        // Now that we've removed all the in-flight monitor updates for channels that are
                                        // still open, we need to replay any monitor updates that are for closed channels,
                                        // creating the neccessary peer_state entries as we go.
                                        let peer_state_mutex = per_peer_state.entry(counterparty_id).or_insert_with(|| {
                                                Mutex::new(peer_state_from_chans(HashMap::new()))
                                        });
                                        let mut peer_state = peer_state_mutex.lock().unwrap();
                                        handle_in_flight_updates!(counterparty_id, chan_in_flight_updates,
                                                funding_txo, monitor, peer_state, "closed ");
                                } else {
                                        log_error!(args.logger, "A ChannelMonitor is missing even though we have in-flight updates for it! This indicates a potentially-critical violation of the chain::Watch API!");
                                        log_error!(args.logger, " The ChannelMonitor for channel {} is missing.",
                                                &funding_txo.to_channel_id());
                                        log_error!(args.logger, " The chain::Watch API *requires* that monitors are persisted durably before returning,");
                                        log_error!(args.logger, " client applications must ensure that ChannelMonitor data is always available and the latest to avoid funds loss!");
                                        log_error!(args.logger, " Without the latest ChannelMonitor we cannot continue without risking funds.");
                                        log_error!(args.logger, " Please ensure the chain::Watch API requirements are met and file a bug report at https://github.com/lightningdevkit/rust-lightning");
                                        return Err(DecodeError::InvalidValue);
                                }
                        }
                }

                // Note that we have to do the above replays before we push new monitor updates.
                pending_background_events.append(&mut close_background_events);

                // If there's any preimages for forwarded HTLCs hanging around in ChannelMonitors we
                // should ensure we try them again on the inbound edge. We put them here and do so after we
                // have a fully-constructed `ChannelManager` at the end.
                let mut pending_claims_to_replay = Vec::new();

                {
                        // If we're tracking pending payments, ensure we haven't lost any by looking at the
                        // ChannelMonitor data for any channels for which we do not have authorative state
                        // (i.e. those for which we just force-closed above or we otherwise don't have a
                        // corresponding `Channel` at all).
                        // This avoids several edge-cases where we would otherwise "forget" about pending
                        // payments which are still in-flight via their on-chain state.
                        // We only rebuild the pending payments map if we were most recently serialized by
                        // 0.0.102+
                        for (_, monitor) in args.channel_monitors.iter() {
                                let counterparty_opt = id_to_peer.get(&monitor.get_funding_txo().0.to_channel_id());
                                if counterparty_opt.is_none() {
                                        for (htlc_source, (htlc, _)) in monitor.get_pending_or_resolved_outbound_htlcs() {
                                                if let HTLCSource::OutboundRoute { payment_id, session_priv, path, .. } = htlc_source {
                                                        if path.hops.is_empty() {
                                                                log_error!(args.logger, "Got an empty path for a pending payment");
                                                                return Err(DecodeError::InvalidValue);
                                                        }

                                                        let path_amt = path.final_value_msat();
                                                        let mut session_priv_bytes = [0; 32];
                                                        session_priv_bytes[..].copy_from_slice(&session_priv[..]);
                                                        match pending_outbounds.pending_outbound_payments.lock().unwrap().entry(payment_id) {
                                                                hash_map::Entry::Occupied(mut entry) => {
                                                                        let newly_added = entry.get_mut().insert(session_priv_bytes, &path);
                                                                        log_info!(args.logger, "{} a pending payment path for {} msat for session priv {} on an existing pending payment with payment hash {}",
                                                                                if newly_added { "Added" } else { "Had" }, path_amt, log_bytes!(session_priv_bytes), &htlc.payment_hash);
                                                                },
                                                                hash_map::Entry::Vacant(entry) => {
                                                                        let path_fee = path.fee_msat();
                                                                        entry.insert(PendingOutboundPayment::Retryable {
                                                                                retry_strategy: None,
                                                                                attempts: PaymentAttempts::new(),
                                                                                payment_params: None,
                                                                                session_privs: [session_priv_bytes].iter().map(|a| *a).collect(),
                                                                                payment_hash: htlc.payment_hash,
                                                                                payment_secret: None, // only used for retries, and we'll never retry on startup
                                                                                payment_metadata: None, // only used for retries, and we'll never retry on startup
                                                                                keysend_preimage: None, // only used for retries, and we'll never retry on startup
                                                                                custom_tlvs: Vec::new(), // only used for retries, and we'll never retry on startup
                                                                                pending_amt_msat: path_amt,
                                                                                pending_fee_msat: Some(path_fee),
                                                                                total_msat: path_amt,
                                                                                starting_block_height: best_block_height,
                                                                                remaining_max_total_routing_fee_msat: None, // only used for retries, and we'll never retry on startup
                                                                        });
                                                                        log_info!(args.logger, "Added a pending payment for {} msat with payment hash {} for path with session priv {}",
                                                                                path_amt, &htlc.payment_hash,  log_bytes!(session_priv_bytes));
                                                                }
                                                        }
                                                }
                                        }
                                        for (htlc_source, (htlc, preimage_opt)) in monitor.get_all_current_outbound_htlcs() {
                                                match htlc_source {
                                                        HTLCSource::PreviousHopData(prev_hop_data) => {
                                                                let pending_forward_matches_htlc = |info: &PendingAddHTLCInfo| {
                                                                        info.prev_funding_outpoint == prev_hop_data.outpoint &&
                                                                                info.prev_htlc_id == prev_hop_data.htlc_id
                                                                };
                                                                // The ChannelMonitor is now responsible for this HTLC's
                                                                // failure/success and will let us know what its outcome is. If we
                                                                // still have an entry for this HTLC in `forward_htlcs` or
                                                                // `pending_intercepted_htlcs`, we were apparently not persisted after
                                                                // the monitor was when forwarding the payment.
                                                                forward_htlcs.retain(|_, forwards| {
                                                                        forwards.retain(|forward| {
                                                                                if let HTLCForwardInfo::AddHTLC(htlc_info) = forward {
                                                                                        if pending_forward_matches_htlc(&htlc_info) {
                                                                                                log_info!(args.logger, "Removing pending to-forward HTLC with hash {} as it was forwarded to the closed channel {}",
                                                                                                        &htlc.payment_hash, &monitor.get_funding_txo().0.to_channel_id());
                                                                                                false
                                                                                        } else { true }
                                                                                } else { true }
                                                                        });
                                                                        !forwards.is_empty()
                                                                });
                                                                pending_intercepted_htlcs.as_mut().unwrap().retain(|intercepted_id, htlc_info| {
                                                                        if pending_forward_matches_htlc(&htlc_info) {
                                                                                log_info!(args.logger, "Removing pending intercepted HTLC with hash {} as it was forwarded to the closed channel {}",
                                                                                        &htlc.payment_hash, &monitor.get_funding_txo().0.to_channel_id());
                                                                                pending_events_read.retain(|(event, _)| {
                                                                                        if let Event::HTLCIntercepted { intercept_id: ev_id, .. } = event {
                                                                                                intercepted_id != ev_id
                                                                                        } else { true }
                                                                                });
                                                                                false
                                                                        } else { true }
                                                                });
                                                        },
                                                        HTLCSource::OutboundRoute { payment_id, session_priv, path, .. } => {
                                                                if let Some(preimage) = preimage_opt {
                                                                        let pending_events = Mutex::new(pending_events_read);
                                                                        // Note that we set `from_onchain` to "false" here,
                                                                        // deliberately keeping the pending payment around forever.
                                                                        // Given it should only occur when we have a channel we're
                                                                        // force-closing for being stale that's okay.
                                                                        // The alternative would be to wipe the state when claiming,
                                                                        // generating a `PaymentPathSuccessful` event but regenerating
                                                                        // it and the `PaymentSent` on every restart until the
                                                                        // `ChannelMonitor` is removed.
                                                                        let compl_action =
                                                                                EventCompletionAction::ReleaseRAAChannelMonitorUpdate {
                                                                                        channel_funding_outpoint: monitor.get_funding_txo().0,
                                                                                        counterparty_node_id: path.hops[0].pubkey,
                                                                                };
                                                                        pending_outbounds.claim_htlc(payment_id, preimage, session_priv,
                                                                                path, false, compl_action, &pending_events, &args.logger);
                                                                        pending_events_read = pending_events.into_inner().unwrap();
                                                                }
                                                        },
                                                }
                                        }
                                }

                                // Whether the downstream channel was closed or not, try to re-apply any payment
                                // preimages from it which may be needed in upstream channels for forwarded
                                // payments.
                                let outbound_claimed_htlcs_iter = monitor.get_all_current_outbound_htlcs()
                                        .into_iter()
                                        .filter_map(|(htlc_source, (htlc, preimage_opt))| {
                                                if let HTLCSource::PreviousHopData(_) = htlc_source {
                                                        if let Some(payment_preimage) = preimage_opt {
                                                                Some((htlc_source, payment_preimage, htlc.amount_msat,
                                                                        // Check if `counterparty_opt.is_none()` to see if the
                                                                        // downstream chan is closed (because we don't have a
                                                                        // channel_id -> peer map entry).
                                                                        counterparty_opt.is_none(),
                                                                        counterparty_opt.cloned().or(monitor.get_counterparty_node_id()),
                                                                        monitor.get_funding_txo().0))
                                                        } else { None }
                                                } else {
                                                        // If it was an outbound payment, we've handled it above - if a preimage
                                                        // came in and we persisted the `ChannelManager` we either handled it and
                                                        // are good to go or the channel force-closed - we don't have to handle the
                                                        // channel still live case here.
                                                        None
                                                }
                                        });
                                for tuple in outbound_claimed_htlcs_iter {
                                        pending_claims_to_replay.push(tuple);
                                }
                        }
                }

                if !forward_htlcs.is_empty() || pending_outbounds.needs_abandon() {
                        // If we have pending HTLCs to forward, assume we either dropped a
                        // `PendingHTLCsForwardable` or the user received it but never processed it as they
                        // shut down before the timer hit. Either way, set the time_forwardable to a small
                        // constant as enough time has likely passed that we should simply handle the forwards
                        // now, or at least after the user gets a chance to reconnect to our peers.
                        pending_events_read.push_back((events::Event::PendingHTLCsForwardable {
                                time_forwardable: Duration::from_secs(2),
                        }, None));
                }

                let inbound_pmt_key_material = args.node_signer.get_inbound_payment_key_material();
                let expanded_inbound_key = inbound_payment::ExpandedKey::new(&inbound_pmt_key_material);

                let mut claimable_payments = HashMap::with_capacity(claimable_htlcs_list.len());
                if let Some(purposes) = claimable_htlc_purposes {
                        if purposes.len() != claimable_htlcs_list.len() {
                                return Err(DecodeError::InvalidValue);
                        }
                        if let Some(onion_fields) = claimable_htlc_onion_fields {
                                if onion_fields.len() != claimable_htlcs_list.len() {
                                        return Err(DecodeError::InvalidValue);
                                }
                                for (purpose, (onion, (payment_hash, htlcs))) in
                                        purposes.into_iter().zip(onion_fields.into_iter().zip(claimable_htlcs_list.into_iter()))
                                {
                                        let existing_payment = claimable_payments.insert(payment_hash, ClaimablePayment {
                                                purpose, htlcs, onion_fields: onion,
                                        });
                                        if existing_payment.is_some() { return Err(DecodeError::InvalidValue); }
                                }
                        } else {
                                for (purpose, (payment_hash, htlcs)) in purposes.into_iter().zip(claimable_htlcs_list.into_iter()) {
                                        let existing_payment = claimable_payments.insert(payment_hash, ClaimablePayment {
                                                purpose, htlcs, onion_fields: None,
                                        });
                                        if existing_payment.is_some() { return Err(DecodeError::InvalidValue); }
                                }
                        }
                } else {
                        // LDK versions prior to 0.0.107 did not write a `pending_htlc_purposes`, but do
                        // include a `_legacy_hop_data` in the `OnionPayload`.
                        for (payment_hash, htlcs) in claimable_htlcs_list.drain(..) {
                                if htlcs.is_empty() {
                                        return Err(DecodeError::InvalidValue);
                                }
                                let purpose = match &htlcs[0].onion_payload {
                                        OnionPayload::Invoice { _legacy_hop_data } => {
                                                if let Some(hop_data) = _legacy_hop_data {
                                                        events::PaymentPurpose::InvoicePayment {
                                                                payment_preimage: match pending_inbound_payments.get(&payment_hash) {
                                                                        Some(inbound_payment) => inbound_payment.payment_preimage,
                                                                        None => match inbound_payment::verify(payment_hash, &hop_data, 0, &expanded_inbound_key, &args.logger) {
                                                                                Ok((payment_preimage, _)) => payment_preimage,
                                                                                Err(()) => {
                                                                                        log_error!(args.logger, "Failed to read claimable payment data for HTLC with payment hash {} - was not a pending inbound payment and didn't match our payment key", &payment_hash);
                                                                                        return Err(DecodeError::InvalidValue);
                                                                                }
                                                                        }
                                                                },
                                                                payment_secret: hop_data.payment_secret,
                                                        }
                                                } else { return Err(DecodeError::InvalidValue); }
                                        },
                                        OnionPayload::Spontaneous(payment_preimage) =>
                                                events::PaymentPurpose::SpontaneousPayment(*payment_preimage),
                                };
                                claimable_payments.insert(payment_hash, ClaimablePayment {
                                        purpose, htlcs, onion_fields: None,
                                });
                        }
                }

                let mut secp_ctx = Secp256k1::new();
                secp_ctx.seeded_randomize(&args.entropy_source.get_secure_random_bytes());

                let our_network_pubkey = match args.node_signer.get_node_id(Recipient::Node) {
                        Ok(key) => key,
                        Err(()) => return Err(DecodeError::InvalidValue)
                };
                if let Some(network_pubkey) = received_network_pubkey {
                        if network_pubkey != our_network_pubkey {
                                log_error!(args.logger, "Key that was generated does not match the existing key.");
                                return Err(DecodeError::InvalidValue);
                        }
                }

                let mut outbound_scid_aliases = HashSet::new();
                for (_peer_node_id, peer_state_mutex) in per_peer_state.iter_mut() {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        for (chan_id, phase) in peer_state.channel_by_id.iter_mut() {
                                if let ChannelPhase::Funded(chan) = phase {
                                        if chan.context.outbound_scid_alias() == 0 {
                                                let mut outbound_scid_alias;
                                                loop {
                                                        outbound_scid_alias = fake_scid::Namespace::OutboundAlias
                                                                .get_fake_scid(best_block_height, &chain_hash, fake_scid_rand_bytes.as_ref().unwrap(), &args.entropy_source);
                                                        if outbound_scid_aliases.insert(outbound_scid_alias) { break; }
                                                }
                                                chan.context.set_outbound_scid_alias(outbound_scid_alias);
                                        } else if !outbound_scid_aliases.insert(chan.context.outbound_scid_alias()) {
                                                // Note that in rare cases its possible to hit this while reading an older
                                                // channel if we just happened to pick a colliding outbound alias above.
                                                log_error!(args.logger, "Got duplicate outbound SCID alias; {}", chan.context.outbound_scid_alias());
                                                return Err(DecodeError::InvalidValue);
                                        }
                                        if chan.context.is_usable() {
                                                if short_to_chan_info.insert(chan.context.outbound_scid_alias(), (chan.context.get_counterparty_node_id(), *chan_id)).is_some() {
                                                        // Note that in rare cases its possible to hit this while reading an older
                                                        // channel if we just happened to pick a colliding outbound alias above.
                                                        log_error!(args.logger, "Got duplicate outbound SCID alias; {}", chan.context.outbound_scid_alias());
                                                        return Err(DecodeError::InvalidValue);
                                                }
                                        }
                                } else {
                                        // We shouldn't have persisted (or read) any unfunded channel types so none should have been
                                        // created in this `channel_by_id` map.
                                        debug_assert!(false);
                                        return Err(DecodeError::InvalidValue);
                                }
                        }
                }

                let bounded_fee_estimator = LowerBoundedFeeEstimator::new(args.fee_estimator);

                for (_, monitor) in args.channel_monitors.iter() {
                        for (payment_hash, payment_preimage) in monitor.get_stored_preimages() {
                                if let Some(payment) = claimable_payments.remove(&payment_hash) {
                                        log_info!(args.logger, "Re-claiming HTLCs with payment hash {} as we've released the preimage to a ChannelMonitor!", &payment_hash);
                                        let mut claimable_amt_msat = 0;
                                        let mut receiver_node_id = Some(our_network_pubkey);
                                        let phantom_shared_secret = payment.htlcs[0].prev_hop.phantom_shared_secret;
                                        if phantom_shared_secret.is_some() {
                                                let phantom_pubkey = args.node_signer.get_node_id(Recipient::PhantomNode)
                                                        .expect("Failed to get node_id for phantom node recipient");
                                                receiver_node_id = Some(phantom_pubkey)
                                        }
                                        for claimable_htlc in &payment.htlcs {
                                                claimable_amt_msat += claimable_htlc.value;

                                                // Add a holding-cell claim of the payment to the Channel, which should be
                                                // applied ~immediately on peer reconnection. Because it won't generate a
                                                // new commitment transaction we can just provide the payment preimage to
                                                // the corresponding ChannelMonitor and nothing else.
                                                //
                                                // We do so directly instead of via the normal ChannelMonitor update
                                                // procedure as the ChainMonitor hasn't yet been initialized, implying
                                                // we're not allowed to call it directly yet. Further, we do the update
                                                // without incrementing the ChannelMonitor update ID as there isn't any
                                                // reason to.
                                                // If we were to generate a new ChannelMonitor update ID here and then
                                                // crash before the user finishes block connect we'd end up force-closing
                                                // this channel as well. On the flip side, there's no harm in restarting
                                                // without the new monitor persisted - we'll end up right back here on
                                                // restart.
                                                let previous_channel_id = claimable_htlc.prev_hop.outpoint.to_channel_id();
                                                if let Some(peer_node_id) = id_to_peer.get(&previous_channel_id){
                                                        let peer_state_mutex = per_peer_state.get(peer_node_id).unwrap();
                                                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                                        let peer_state = &mut *peer_state_lock;
                                                        if let Some(ChannelPhase::Funded(channel)) = peer_state.channel_by_id.get_mut(&previous_channel_id) {
                                                                channel.claim_htlc_while_disconnected_dropping_mon_update(claimable_htlc.prev_hop.htlc_id, payment_preimage, &args.logger);
                                                        }
                                                }
                                                if let Some(previous_hop_monitor) = args.channel_monitors.get(&claimable_htlc.prev_hop.outpoint) {
                                                        previous_hop_monitor.provide_payment_preimage(&payment_hash, &payment_preimage, &args.tx_broadcaster, &bounded_fee_estimator, &args.logger);
                                                }
                                        }
                                        pending_events_read.push_back((events::Event::PaymentClaimed {
                                                receiver_node_id,
                                                payment_hash,
                                                purpose: payment.purpose,
                                                amount_msat: claimable_amt_msat,
                                                htlcs: payment.htlcs.iter().map(events::ClaimedHTLC::from).collect(),
                                                sender_intended_total_msat: payment.htlcs.first().map(|htlc| htlc.total_msat),
                                        }, None));
                                }
                        }
                }

                for (node_id, monitor_update_blocked_actions) in monitor_update_blocked_actions_per_peer.unwrap() {
                        if let Some(peer_state) = per_peer_state.get(&node_id) {
                                for (_, actions) in monitor_update_blocked_actions.iter() {
                                        for action in actions.iter() {
                                                if let MonitorUpdateCompletionAction::EmitEventAndFreeOtherChannel {
                                                        downstream_counterparty_and_funding_outpoint:
                                                                Some((blocked_node_id, blocked_channel_outpoint, blocking_action)), ..
                                                } = action {
                                                        if let Some(blocked_peer_state) = per_peer_state.get(&blocked_node_id) {
                                                                log_trace!(args.logger,
                                                                        "Holding the next revoke_and_ack from {} until the preimage is durably persisted in the inbound edge's ChannelMonitor",
                                                                        blocked_channel_outpoint.to_channel_id());
                                                                blocked_peer_state.lock().unwrap().actions_blocking_raa_monitor_updates
                                                                        .entry(blocked_channel_outpoint.to_channel_id())
                                                                        .or_insert_with(Vec::new).push(blocking_action.clone());
                                                        } else {
                                                                // If the channel we were blocking has closed, we don't need to
                                                                // worry about it - the blocked monitor update should never have
                                                                // been released from the `Channel` object so it can't have
                                                                // completed, and if the channel closed there's no reason to bother
                                                                // anymore.
                                                        }
                                                }
                                                if let MonitorUpdateCompletionAction::FreeOtherChannelImmediately { .. } = action {
                                                        debug_assert!(false, "Non-event-generating channel freeing should not appear in our queue");
                                                }
                                        }
                                }
                                peer_state.lock().unwrap().monitor_update_blocked_actions = monitor_update_blocked_actions;
                        } else {
                                log_error!(args.logger, "Got blocked actions without a per-peer-state for {}", node_id);
                                return Err(DecodeError::InvalidValue);
                        }
                }

                let channel_manager = ChannelManager {
                        chain_hash,
                        fee_estimator: bounded_fee_estimator,
                        chain_monitor: args.chain_monitor,
                        tx_broadcaster: args.tx_broadcaster,
                        router: args.router,

                        best_block: RwLock::new(BestBlock::new(best_block_hash, best_block_height)),

                        inbound_payment_key: expanded_inbound_key,
                        pending_inbound_payments: Mutex::new(pending_inbound_payments),
                        pending_outbound_payments: pending_outbounds,
                        pending_intercepted_htlcs: Mutex::new(pending_intercepted_htlcs.unwrap()),

                        forward_htlcs: Mutex::new(forward_htlcs),
                        claimable_payments: Mutex::new(ClaimablePayments { claimable_payments, pending_claiming_payments: pending_claiming_payments.unwrap() }),
                        outbound_scid_aliases: Mutex::new(outbound_scid_aliases),
                        id_to_peer: Mutex::new(id_to_peer),
                        short_to_chan_info: FairRwLock::new(short_to_chan_info),
                        fake_scid_rand_bytes: fake_scid_rand_bytes.unwrap(),

                        probing_cookie_secret: probing_cookie_secret.unwrap(),

                        our_network_pubkey,
                        secp_ctx,

                        highest_seen_timestamp: AtomicUsize::new(highest_seen_timestamp as usize),

                        per_peer_state: FairRwLock::new(per_peer_state),

                        pending_events: Mutex::new(pending_events_read),
                        pending_events_processor: AtomicBool::new(false),
                        pending_background_events: Mutex::new(pending_background_events),
                        total_consistency_lock: RwLock::new(()),
                        background_events_processed_since_startup: AtomicBool::new(false),

                        event_persist_notifier: Notifier::new(),
                        needs_persist_flag: AtomicBool::new(false),

                        funding_batch_states: Mutex::new(BTreeMap::new()),

                        pending_offers_messages: Mutex::new(Vec::new()),

                        entropy_source: args.entropy_source,
                        node_signer: args.node_signer,
                        signer_provider: args.signer_provider,

                        logger: args.logger,
                        default_configuration: args.default_config,
                };

                for htlc_source in failed_htlcs.drain(..) {
                        let (source, payment_hash, counterparty_node_id, channel_id) = htlc_source;
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id };
                        let reason = HTLCFailReason::from_failure_code(0x4000 | 8);
                        channel_manager.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
                }

                for (source, preimage, downstream_value, downstream_closed, downstream_node_id, downstream_funding) in pending_claims_to_replay {
                        // We use `downstream_closed` in place of `from_onchain` here just as a guess - we
                        // don't remember in the `ChannelMonitor` where we got a preimage from, but if the
                        // channel is closed we just assume that it probably came from an on-chain claim.
                        channel_manager.claim_funds_internal(source, preimage, Some(downstream_value),
                                downstream_closed, true, downstream_node_id, downstream_funding);
                }

                //TODO: Broadcast channel update for closed channels, but only after we've made a
                //connection or two.

                Ok((best_block_hash.clone(), channel_manager))
        }
}

#[cfg(test)]
mod tests {
        use bitcoin::hashes::Hash;
        use bitcoin::hashes::sha256::Hash as Sha256;
        use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
        use core::sync::atomic::Ordering;
        use crate::events::{Event, HTLCDestination, MessageSendEvent, MessageSendEventsProvider, ClosureReason};
        use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
        use crate::ln::ChannelId;
        use crate::ln::channelmanager::{create_recv_pending_htlc_info, inbound_payment, PaymentId, PaymentSendFailure, RecipientOnionFields, InterceptId};
        use crate::ln::features::{ChannelFeatures, NodeFeatures};
        use crate::ln::functional_test_utils::*;
        use crate::ln::msgs::{self, ErrorAction};
        use crate::ln::msgs::ChannelMessageHandler;
        use crate::routing::router::{Path, PaymentParameters, RouteHop, RouteParameters, find_route};
        use crate::util::errors::APIError;
        use crate::util::test_utils;
        use crate::util::config::{ChannelConfig, ChannelConfigUpdate};
        use crate::sign::EntropySource;

        #[test]
        fn test_notify_limits() {
                // Check that a few cases which don't require the persistence of a new ChannelManager,
                // indeed, do not cause the persistence of a new ChannelManager.
                let chanmon_cfgs = create_chanmon_cfgs(3);
                let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
                let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

                // All nodes start with a persistable update pending as `create_network` connects each node
                // with all other nodes to make most tests simpler.
                assert!(nodes[0].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert!(nodes[1].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert!(nodes[2].node.get_event_or_persistence_needed_future().poll_is_complete());

                let mut chan = create_announced_chan_between_nodes(&nodes, 0, 1);

                // We check that the channel info nodes have doesn't change too early, even though we try
                // to connect messages with new values
                chan.0.contents.fee_base_msat *= 2;
                chan.1.contents.fee_base_msat *= 2;
                let node_a_chan_info = nodes[0].node.list_channels_with_counterparty(
                        &nodes[1].node.get_our_node_id()).pop().unwrap();
                let node_b_chan_info = nodes[1].node.list_channels_with_counterparty(
                        &nodes[0].node.get_our_node_id()).pop().unwrap();

                // The first two nodes (which opened a channel) should now require fresh persistence
                assert!(nodes[0].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert!(nodes[1].node.get_event_or_persistence_needed_future().poll_is_complete());
                // ... but the last node should not.
                assert!(!nodes[2].node.get_event_or_persistence_needed_future().poll_is_complete());
                // After persisting the first two nodes they should no longer need fresh persistence.
                assert!(!nodes[0].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert!(!nodes[1].node.get_event_or_persistence_needed_future().poll_is_complete());

                // Node 3, unrelated to the only channel, shouldn't care if it receives a channel_update
                // about the channel.
                nodes[2].node.handle_channel_update(&nodes[1].node.get_our_node_id(), &chan.0);
                nodes[2].node.handle_channel_update(&nodes[1].node.get_our_node_id(), &chan.1);
                assert!(!nodes[2].node.get_event_or_persistence_needed_future().poll_is_complete());

                // The nodes which are a party to the channel should also ignore messages from unrelated
                // parties.
                nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan.0);
                nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan.1);
                nodes[1].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan.0);
                nodes[1].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan.1);
                assert!(!nodes[0].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert!(!nodes[1].node.get_event_or_persistence_needed_future().poll_is_complete());

                // At this point the channel info given by peers should still be the same.
                assert_eq!(nodes[0].node.list_channels()[0], node_a_chan_info);
                assert_eq!(nodes[1].node.list_channels()[0], node_b_chan_info);

                // An earlier version of handle_channel_update didn't check the directionality of the
                // update message and would always update the local fee info, even if our peer was
                // (spuriously) forwarding us our own channel_update.
                let as_node_one = nodes[0].node.get_our_node_id().serialize()[..] < nodes[1].node.get_our_node_id().serialize()[..];
                let as_update = if as_node_one == (chan.0.contents.flags & 1 == 0 /* chan.0 is from node one */) { &chan.0 } else { &chan.1 };
                let bs_update = if as_node_one == (chan.0.contents.flags & 1 == 0 /* chan.0 is from node one */) { &chan.1 } else { &chan.0 };

                // First deliver each peers' own message, checking that the node doesn't need to be
                // persisted and that its channel info remains the same.
                nodes[0].node.handle_channel_update(&nodes[1].node.get_our_node_id(), &as_update);
                nodes[1].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &bs_update);
                assert!(!nodes[0].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert!(!nodes[1].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert_eq!(nodes[0].node.list_channels()[0], node_a_chan_info);
                assert_eq!(nodes[1].node.list_channels()[0], node_b_chan_info);

                // Finally, deliver the other peers' message, ensuring each node needs to be persisted and
                // the channel info has updated.
                nodes[0].node.handle_channel_update(&nodes[1].node.get_our_node_id(), &bs_update);
                nodes[1].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &as_update);
                assert!(nodes[0].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert!(nodes[1].node.get_event_or_persistence_needed_future().poll_is_complete());
                assert_ne!(nodes[0].node.list_channels()[0], node_a_chan_info);
                assert_ne!(nodes[1].node.list_channels()[0], node_b_chan_info);
        }

        #[test]
        fn test_keysend_dup_hash_partial_mpp() {
                // Test that a keysend payment with a duplicate hash to an existing partial MPP payment fails as
                // expected.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
                create_announced_chan_between_nodes(&nodes, 0, 1);

                // First, send a partial MPP payment.
                let (route, our_payment_hash, payment_preimage, payment_secret) = get_route_and_payment_hash!(&nodes[0], nodes[1], 100_000);
                let mut mpp_route = route.clone();
                mpp_route.paths.push(mpp_route.paths[0].clone());

                let payment_id = PaymentId([42; 32]);
                // Use the utility function send_payment_along_path to send the payment with MPP data which
                // indicates there are more HTLCs coming.
                let cur_height = CHAN_CONFIRM_DEPTH + 1; // route_payment calls send_payment, which adds 1 to the current height. So we do the same here to match.
                let session_privs = nodes[0].node.test_add_new_pending_payment(our_payment_hash,
                        RecipientOnionFields::secret_only(payment_secret), payment_id, &mpp_route).unwrap();
                nodes[0].node.test_send_payment_along_path(&mpp_route.paths[0], &our_payment_hash,
                        RecipientOnionFields::secret_only(payment_secret), 200_000, cur_height, payment_id, &None, session_privs[0]).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                pass_along_path(&nodes[0], &[&nodes[1]], 200_000, our_payment_hash, Some(payment_secret), events.drain(..).next().unwrap(), false, None);

                // Next, send a keysend payment with the same payment_hash and make sure it fails.
                nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage),
                        RecipientOnionFields::spontaneous_empty(), PaymentId(payment_preimage.0)).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                let ev = events.drain(..).next().unwrap();
                let payment_event = SendEvent::from_event(ev);
                nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
                check_added_monitors!(nodes[1], 0);
                commitment_signed_dance!(nodes[1], nodes[0], payment_event.commitment_msg, false);
                expect_pending_htlcs_forwardable!(nodes[1]);
                expect_pending_htlcs_forwardable_and_htlc_handling_failed!(nodes[1], vec![HTLCDestination::FailedPayment { payment_hash: our_payment_hash }]);
                check_added_monitors!(nodes[1], 1);
                let updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
                assert!(updates.update_add_htlcs.is_empty());
                assert!(updates.update_fulfill_htlcs.is_empty());
                assert_eq!(updates.update_fail_htlcs.len(), 1);
                assert!(updates.update_fail_malformed_htlcs.is_empty());
                assert!(updates.update_fee.is_none());
                nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
                commitment_signed_dance!(nodes[0], nodes[1], updates.commitment_signed, true, true);
                expect_payment_failed!(nodes[0], our_payment_hash, true);

                // Send the second half of the original MPP payment.
                nodes[0].node.test_send_payment_along_path(&mpp_route.paths[1], &our_payment_hash,
                        RecipientOnionFields::secret_only(payment_secret), 200_000, cur_height, payment_id, &None, session_privs[1]).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                pass_along_path(&nodes[0], &[&nodes[1]], 200_000, our_payment_hash, Some(payment_secret), events.drain(..).next().unwrap(), true, None);

                // Claim the full MPP payment. Note that we can't use a test utility like
                // claim_funds_along_route because the ordering of the messages causes the second half of the
                // payment to be put in the holding cell, which confuses the test utilities. So we exchange the
                // lightning messages manually.
                nodes[1].node.claim_funds(payment_preimage);
                expect_payment_claimed!(nodes[1], our_payment_hash, 200_000);
                check_added_monitors!(nodes[1], 2);

                let bs_first_updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
                nodes[0].node.handle_update_fulfill_htlc(&nodes[1].node.get_our_node_id(), &bs_first_updates.update_fulfill_htlcs[0]);
                expect_payment_sent(&nodes[0], payment_preimage, None, false, false);
                nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_first_updates.commitment_signed);
                check_added_monitors!(nodes[0], 1);
                let (as_first_raa, as_first_cs) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
                nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_first_raa);
                check_added_monitors!(nodes[1], 1);
                let bs_second_updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
                nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_first_cs);
                check_added_monitors!(nodes[1], 1);
                let bs_first_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
                nodes[0].node.handle_update_fulfill_htlc(&nodes[1].node.get_our_node_id(), &bs_second_updates.update_fulfill_htlcs[0]);
                nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_second_updates.commitment_signed);
                check_added_monitors!(nodes[0], 1);
                let as_second_raa = get_event_msg!(nodes[0], MessageSendEvent::SendRevokeAndACK, nodes[1].node.get_our_node_id());
                nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_first_raa);
                let as_second_updates = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
                check_added_monitors!(nodes[0], 1);
                nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_second_raa);
                check_added_monitors!(nodes[1], 1);
                nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_second_updates.commitment_signed);
                check_added_monitors!(nodes[1], 1);
                let bs_third_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
                nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_third_raa);
                check_added_monitors!(nodes[0], 1);

                // Note that successful MPP payments will generate a single PaymentSent event upon the first
                // path's success and a PaymentPathSuccessful event for each path's success.
                let events = nodes[0].node.get_and_clear_pending_events();
                assert_eq!(events.len(), 2);
                match events[0] {
                        Event::PaymentPathSuccessful { payment_id: ref actual_payment_id, ref payment_hash, ref path } => {
                                assert_eq!(payment_id, *actual_payment_id);
                                assert_eq!(our_payment_hash, *payment_hash.as_ref().unwrap());
                                assert_eq!(route.paths[0], *path);
                        },
                        _ => panic!("Unexpected event"),
                }
                match events[1] {
                        Event::PaymentPathSuccessful { payment_id: ref actual_payment_id, ref payment_hash, ref path } => {
                                assert_eq!(payment_id, *actual_payment_id);
                                assert_eq!(our_payment_hash, *payment_hash.as_ref().unwrap());
                                assert_eq!(route.paths[0], *path);
                        },
                        _ => panic!("Unexpected event"),
                }
        }

        #[test]
        fn test_keysend_dup_payment_hash() {
                do_test_keysend_dup_payment_hash(false);
                do_test_keysend_dup_payment_hash(true);
        }

        fn do_test_keysend_dup_payment_hash(accept_mpp_keysend: bool) {
                // (1): Test that a keysend payment with a duplicate payment hash to an existing pending
                //      outbound regular payment fails as expected.
                // (2): Test that a regular payment with a duplicate payment hash to an existing keysend payment
                //      fails as expected.
                // (3): Test that a keysend payment with a duplicate payment hash to an existing keysend
                //      payment fails as expected. When `accept_mpp_keysend` is false, this tests that we
                //      reject MPP keysend payments, since in this case where the payment has no payment
                //      secret, a keysend payment with a duplicate hash is basically an MPP keysend. If
                //      `accept_mpp_keysend` is true, this tests that we only accept MPP keysends with
                //      payment secrets and reject otherwise.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let mut mpp_keysend_cfg = test_default_channel_config();
                mpp_keysend_cfg.accept_mpp_keysend = accept_mpp_keysend;
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, Some(mpp_keysend_cfg)]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
                create_announced_chan_between_nodes(&nodes, 0, 1);
                let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();

                // To start (1), send a regular payment but don't claim it.
                let expected_route = [&nodes[1]];
                let (payment_preimage, payment_hash, ..) = route_payment(&nodes[0], &expected_route, 100_000);

                // Next, attempt a keysend payment and make sure it fails.
                let route_params = RouteParameters::from_payment_params_and_value(
                        PaymentParameters::for_keysend(expected_route.last().unwrap().node.get_our_node_id(),
                        TEST_FINAL_CLTV, false), 100_000);
                let route = find_route(
                        &nodes[0].node.get_our_node_id(), &route_params, &nodes[0].network_graph,
                        None, nodes[0].logger, &scorer, &Default::default(), &random_seed_bytes
                ).unwrap();
                nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage),
                        RecipientOnionFields::spontaneous_empty(), PaymentId(payment_preimage.0)).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                let ev = events.drain(..).next().unwrap();
                let payment_event = SendEvent::from_event(ev);
                nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
                check_added_monitors!(nodes[1], 0);
                commitment_signed_dance!(nodes[1], nodes[0], payment_event.commitment_msg, false);
                // We have to forward pending HTLCs twice - once tries to forward the payment forward (and
                // fails), the second will process the resulting failure and fail the HTLC backward
                expect_pending_htlcs_forwardable!(nodes[1]);
                expect_pending_htlcs_forwardable_and_htlc_handling_failed!(nodes[1], vec![HTLCDestination::FailedPayment { payment_hash }]);
                check_added_monitors!(nodes[1], 1);
                let updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
                assert!(updates.update_add_htlcs.is_empty());
                assert!(updates.update_fulfill_htlcs.is_empty());
                assert_eq!(updates.update_fail_htlcs.len(), 1);
                assert!(updates.update_fail_malformed_htlcs.is_empty());
                assert!(updates.update_fee.is_none());
                nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
                commitment_signed_dance!(nodes[0], nodes[1], updates.commitment_signed, true, true);
                expect_payment_failed!(nodes[0], payment_hash, true);

                // Finally, claim the original payment.
                claim_payment(&nodes[0], &expected_route, payment_preimage);

                // To start (2), send a keysend payment but don't claim it.
                let payment_preimage = PaymentPreimage([42; 32]);
                let route = find_route(
                        &nodes[0].node.get_our_node_id(), &route_params, &nodes[0].network_graph,
                        None, nodes[0].logger, &scorer, &Default::default(), &random_seed_bytes
                ).unwrap();
                let payment_hash = nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage),
                        RecipientOnionFields::spontaneous_empty(), PaymentId(payment_preimage.0)).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                let event = events.pop().unwrap();
                let path = vec![&nodes[1]];
                pass_along_path(&nodes[0], &path, 100_000, payment_hash, None, event, true, Some(payment_preimage));

                // Next, attempt a regular payment and make sure it fails.
                let payment_secret = PaymentSecret([43; 32]);
                nodes[0].node.send_payment_with_route(&route, payment_hash,
                        RecipientOnionFields::secret_only(payment_secret), PaymentId(payment_hash.0)).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                let ev = events.drain(..).next().unwrap();
                let payment_event = SendEvent::from_event(ev);
                nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
                check_added_monitors!(nodes[1], 0);
                commitment_signed_dance!(nodes[1], nodes[0], payment_event.commitment_msg, false);
                expect_pending_htlcs_forwardable!(nodes[1]);
                expect_pending_htlcs_forwardable_and_htlc_handling_failed!(nodes[1], vec![HTLCDestination::FailedPayment { payment_hash }]);
                check_added_monitors!(nodes[1], 1);
                let updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
                assert!(updates.update_add_htlcs.is_empty());
                assert!(updates.update_fulfill_htlcs.is_empty());
                assert_eq!(updates.update_fail_htlcs.len(), 1);
                assert!(updates.update_fail_malformed_htlcs.is_empty());
                assert!(updates.update_fee.is_none());
                nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
                commitment_signed_dance!(nodes[0], nodes[1], updates.commitment_signed, true, true);
                expect_payment_failed!(nodes[0], payment_hash, true);

                // Finally, succeed the keysend payment.
                claim_payment(&nodes[0], &expected_route, payment_preimage);

                // To start (3), send a keysend payment but don't claim it.
                let payment_id_1 = PaymentId([44; 32]);
                let payment_hash = nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage),
                        RecipientOnionFields::spontaneous_empty(), payment_id_1).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                let event = events.pop().unwrap();
                let path = vec![&nodes[1]];
                pass_along_path(&nodes[0], &path, 100_000, payment_hash, None, event, true, Some(payment_preimage));

                // Next, attempt a keysend payment and make sure it fails.
                let route_params = RouteParameters::from_payment_params_and_value(
                        PaymentParameters::for_keysend(expected_route.last().unwrap().node.get_our_node_id(), TEST_FINAL_CLTV, false),
                        100_000
                );
                let route = find_route(
                        &nodes[0].node.get_our_node_id(), &route_params, &nodes[0].network_graph,
                        None, nodes[0].logger, &scorer, &Default::default(), &random_seed_bytes
                ).unwrap();
                let payment_id_2 = PaymentId([45; 32]);
                nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage),
                        RecipientOnionFields::spontaneous_empty(), payment_id_2).unwrap();
                check_added_monitors!(nodes[0], 1);
                let mut events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                let ev = events.drain(..).next().unwrap();
                let payment_event = SendEvent::from_event(ev);
                nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
                check_added_monitors!(nodes[1], 0);
                commitment_signed_dance!(nodes[1], nodes[0], payment_event.commitment_msg, false);
                expect_pending_htlcs_forwardable!(nodes[1]);
                expect_pending_htlcs_forwardable_and_htlc_handling_failed!(nodes[1], vec![HTLCDestination::FailedPayment { payment_hash }]);
                check_added_monitors!(nodes[1], 1);
                let updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
                assert!(updates.update_add_htlcs.is_empty());
                assert!(updates.update_fulfill_htlcs.is_empty());
                assert_eq!(updates.update_fail_htlcs.len(), 1);
                assert!(updates.update_fail_malformed_htlcs.is_empty());
                assert!(updates.update_fee.is_none());
                nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
                commitment_signed_dance!(nodes[0], nodes[1], updates.commitment_signed, true, true);
                expect_payment_failed!(nodes[0], payment_hash, true);

                // Finally, claim the original payment.
                claim_payment(&nodes[0], &expected_route, payment_preimage);
        }

        #[test]
        fn test_keysend_hash_mismatch() {
                // Test that if we receive a keysend `update_add_htlc` msg, we fail as expected if the keysend
                // preimage doesn't match the msg's payment hash.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                let payer_pubkey = nodes[0].node.get_our_node_id();
                let payee_pubkey = nodes[1].node.get_our_node_id();

                let _chan = create_chan_between_nodes(&nodes[0], &nodes[1]);
                let route_params = RouteParameters::from_payment_params_and_value(
                        PaymentParameters::for_keysend(payee_pubkey, 40, false), 10_000);
                let network_graph = nodes[0].network_graph;
                let first_hops = nodes[0].node.list_usable_channels();
                let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
                let route = find_route(
                        &payer_pubkey, &route_params, &network_graph, Some(&first_hops.iter().collect::<Vec<_>>()),
                        nodes[0].logger, &scorer, &Default::default(), &random_seed_bytes
                ).unwrap();

                let test_preimage = PaymentPreimage([42; 32]);
                let mismatch_payment_hash = PaymentHash([43; 32]);
                let session_privs = nodes[0].node.test_add_new_pending_payment(mismatch_payment_hash,
                        RecipientOnionFields::spontaneous_empty(), PaymentId(mismatch_payment_hash.0), &route).unwrap();
                nodes[0].node.test_send_payment_internal(&route, mismatch_payment_hash,
                        RecipientOnionFields::spontaneous_empty(), Some(test_preimage), PaymentId(mismatch_payment_hash.0), None, session_privs).unwrap();
                check_added_monitors!(nodes[0], 1);

                let updates = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
                assert_eq!(updates.update_add_htlcs.len(), 1);
                assert!(updates.update_fulfill_htlcs.is_empty());
                assert!(updates.update_fail_htlcs.is_empty());
                assert!(updates.update_fail_malformed_htlcs.is_empty());
                assert!(updates.update_fee.is_none());
                nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &updates.update_add_htlcs[0]);

                nodes[1].logger.assert_log_contains("lightning::ln::channelmanager", "Payment preimage didn't match payment hash", 1);
        }

        #[test]
        fn test_keysend_msg_with_secret_err() {
                // Test that we error as expected if we receive a keysend payment that includes a payment
                // secret when we don't support MPP keysend.
                let mut reject_mpp_keysend_cfg = test_default_channel_config();
                reject_mpp_keysend_cfg.accept_mpp_keysend = false;
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, Some(reject_mpp_keysend_cfg)]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                let payer_pubkey = nodes[0].node.get_our_node_id();
                let payee_pubkey = nodes[1].node.get_our_node_id();

                let _chan = create_chan_between_nodes(&nodes[0], &nodes[1]);
                let route_params = RouteParameters::from_payment_params_and_value(
                        PaymentParameters::for_keysend(payee_pubkey, 40, false), 10_000);
                let network_graph = nodes[0].network_graph;
                let first_hops = nodes[0].node.list_usable_channels();
                let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
                let route = find_route(
                        &payer_pubkey, &route_params, &network_graph, Some(&first_hops.iter().collect::<Vec<_>>()),
                        nodes[0].logger, &scorer, &Default::default(), &random_seed_bytes
                ).unwrap();

                let test_preimage = PaymentPreimage([42; 32]);
                let test_secret = PaymentSecret([43; 32]);
                let payment_hash = PaymentHash(Sha256::hash(&test_preimage.0).to_byte_array());
                let session_privs = nodes[0].node.test_add_new_pending_payment(payment_hash,
                        RecipientOnionFields::secret_only(test_secret), PaymentId(payment_hash.0), &route).unwrap();
                nodes[0].node.test_send_payment_internal(&route, payment_hash,
                        RecipientOnionFields::secret_only(test_secret), Some(test_preimage),
                        PaymentId(payment_hash.0), None, session_privs).unwrap();
                check_added_monitors!(nodes[0], 1);

                let updates = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
                assert_eq!(updates.update_add_htlcs.len(), 1);
                assert!(updates.update_fulfill_htlcs.is_empty());
                assert!(updates.update_fail_htlcs.is_empty());
                assert!(updates.update_fail_malformed_htlcs.is_empty());
                assert!(updates.update_fee.is_none());
                nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &updates.update_add_htlcs[0]);

                nodes[1].logger.assert_log_contains("lightning::ln::channelmanager", "We don't support MPP keysend payments", 1);
        }

        #[test]
        fn test_multi_hop_missing_secret() {
                let chanmon_cfgs = create_chanmon_cfgs(4);
                let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
                let nodes = create_network(4, &node_cfgs, &node_chanmgrs);

                let chan_1_id = create_announced_chan_between_nodes(&nodes, 0, 1).0.contents.short_channel_id;
                let chan_2_id = create_announced_chan_between_nodes(&nodes, 0, 2).0.contents.short_channel_id;
                let chan_3_id = create_announced_chan_between_nodes(&nodes, 1, 3).0.contents.short_channel_id;
                let chan_4_id = create_announced_chan_between_nodes(&nodes, 2, 3).0.contents.short_channel_id;

                // Marshall an MPP route.
                let (mut route, payment_hash, _, _) = get_route_and_payment_hash!(&nodes[0], nodes[3], 100000);
                let path = route.paths[0].clone();
                route.paths.push(path);
                route.paths[0].hops[0].pubkey = nodes[1].node.get_our_node_id();
                route.paths[0].hops[0].short_channel_id = chan_1_id;
                route.paths[0].hops[1].short_channel_id = chan_3_id;
                route.paths[1].hops[0].pubkey = nodes[2].node.get_our_node_id();
                route.paths[1].hops[0].short_channel_id = chan_2_id;
                route.paths[1].hops[1].short_channel_id = chan_4_id;

                match nodes[0].node.send_payment_with_route(&route, payment_hash,
                        RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0))
                .unwrap_err() {
                        PaymentSendFailure::ParameterError(APIError::APIMisuseError { ref err }) => {
                                assert!(regex::Regex::new(r"Payment secret is required for multi-path payments").unwrap().is_match(err))
                        },
                        _ => panic!("unexpected error")
                }
        }

        #[test]
        fn test_drop_disconnected_peers_when_removing_channels() {
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                let chan = create_announced_chan_between_nodes(&nodes, 0, 1);

                nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id());
                nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());

                nodes[0].node.force_close_broadcasting_latest_txn(&chan.2, &nodes[1].node.get_our_node_id()).unwrap();
                check_closed_broadcast!(nodes[0], true);
                check_added_monitors!(nodes[0], 1);
                check_closed_event!(nodes[0], 1, ClosureReason::HolderForceClosed, [nodes[1].node.get_our_node_id()], 100000);

                {
                        // Assert that nodes[1] is awaiting removal for nodes[0] once nodes[1] has been
                        // disconnected and the channel between has been force closed.
                        let nodes_0_per_peer_state = nodes[0].node.per_peer_state.read().unwrap();
                        // Assert that nodes[1] isn't removed before `timer_tick_occurred` has been executed.
                        assert_eq!(nodes_0_per_peer_state.len(), 1);
                        assert!(nodes_0_per_peer_state.get(&nodes[1].node.get_our_node_id()).is_some());
                }

                nodes[0].node.timer_tick_occurred();

                {
                        // Assert that nodes[1] has now been removed.
                        assert_eq!(nodes[0].node.per_peer_state.read().unwrap().len(), 0);
                }
        }

        #[test]
        fn bad_inbound_payment_hash() {
                // Add coverage for checking that a user-provided payment hash matches the payment secret.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                let (_, payment_hash, payment_secret) = get_payment_preimage_hash!(&nodes[0]);
                let payment_data = msgs::FinalOnionHopData {
                        payment_secret,
                        total_msat: 100_000,
                };

                // Ensure that if the payment hash given to `inbound_payment::verify` differs from the original,
                // payment verification fails as expected.
                let mut bad_payment_hash = payment_hash.clone();
                bad_payment_hash.0[0] += 1;
                match inbound_payment::verify(bad_payment_hash, &payment_data, nodes[0].node.highest_seen_timestamp.load(Ordering::Acquire) as u64, &nodes[0].node.inbound_payment_key, &nodes[0].logger) {
                        Ok(_) => panic!("Unexpected ok"),
                        Err(()) => {
                                nodes[0].logger.assert_log_contains("lightning::ln::inbound_payment", "Failing HTLC with user-generated payment_hash", 1);
                        }
                }

                // Check that using the original payment hash succeeds.
                assert!(inbound_payment::verify(payment_hash, &payment_data, nodes[0].node.highest_seen_timestamp.load(Ordering::Acquire) as u64, &nodes[0].node.inbound_payment_key, &nodes[0].logger).is_ok());
        }

        #[test]
        fn test_id_to_peer_coverage() {
                // Test that the `ChannelManager:id_to_peer` contains channels which have been assigned
                // a `channel_id` (i.e. have had the funding tx created), and that they are removed once
                // the channel is successfully closed.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 1_000_000, 500_000_000, 42, None, None).unwrap();
                let open_channel = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
                nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel);
                let accept_channel = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
                nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), &accept_channel);

                let (temporary_channel_id, tx, _funding_output) = create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 1_000_000, 42);
                let channel_id = ChannelId::from_bytes(tx.txid().to_byte_array());
                {
                        // Ensure that the `id_to_peer` map is empty until either party has received the
                        // funding transaction, and have the real `channel_id`.
                        assert_eq!(nodes[0].node.id_to_peer.lock().unwrap().len(), 0);
                        assert_eq!(nodes[1].node.id_to_peer.lock().unwrap().len(), 0);
                }

                nodes[0].node.funding_transaction_generated(&temporary_channel_id, &nodes[1].node.get_our_node_id(), tx.clone()).unwrap();
                {
                        // Assert that `nodes[0]`'s `id_to_peer` map is populated with the channel as soon as
                        // as it has the funding transaction.
                        let nodes_0_lock = nodes[0].node.id_to_peer.lock().unwrap();
                        assert_eq!(nodes_0_lock.len(), 1);
                        assert!(nodes_0_lock.contains_key(&channel_id));
                }

                assert_eq!(nodes[1].node.id_to_peer.lock().unwrap().len(), 0);

                let funding_created_msg = get_event_msg!(nodes[0], MessageSendEvent::SendFundingCreated, nodes[1].node.get_our_node_id());

                nodes[1].node.handle_funding_created(&nodes[0].node.get_our_node_id(), &funding_created_msg);
                {
                        let nodes_0_lock = nodes[0].node.id_to_peer.lock().unwrap();
                        assert_eq!(nodes_0_lock.len(), 1);
                        assert!(nodes_0_lock.contains_key(&channel_id));
                }
                expect_channel_pending_event(&nodes[1], &nodes[0].node.get_our_node_id());

                {
                        // Assert that `nodes[1]`'s `id_to_peer` map is populated with the channel as soon as
                        // as it has the funding transaction.
                        let nodes_1_lock = nodes[1].node.id_to_peer.lock().unwrap();
                        assert_eq!(nodes_1_lock.len(), 1);
                        assert!(nodes_1_lock.contains_key(&channel_id));
                }
                check_added_monitors!(nodes[1], 1);
                let funding_signed = get_event_msg!(nodes[1], MessageSendEvent::SendFundingSigned, nodes[0].node.get_our_node_id());
                nodes[0].node.handle_funding_signed(&nodes[1].node.get_our_node_id(), &funding_signed);
                check_added_monitors!(nodes[0], 1);
                expect_channel_pending_event(&nodes[0], &nodes[1].node.get_our_node_id());
                let (channel_ready, _) = create_chan_between_nodes_with_value_confirm(&nodes[0], &nodes[1], &tx);
                let (announcement, nodes_0_update, nodes_1_update) = create_chan_between_nodes_with_value_b(&nodes[0], &nodes[1], &channel_ready);
                update_nodes_with_chan_announce(&nodes, 0, 1, &announcement, &nodes_0_update, &nodes_1_update);

                nodes[0].node.close_channel(&channel_id, &nodes[1].node.get_our_node_id()).unwrap();
                nodes[1].node.handle_shutdown(&nodes[0].node.get_our_node_id(), &get_event_msg!(nodes[0], MessageSendEvent::SendShutdown, nodes[1].node.get_our_node_id()));
                let nodes_1_shutdown = get_event_msg!(nodes[1], MessageSendEvent::SendShutdown, nodes[0].node.get_our_node_id());
                nodes[0].node.handle_shutdown(&nodes[1].node.get_our_node_id(), &nodes_1_shutdown);

                let closing_signed_node_0 = get_event_msg!(nodes[0], MessageSendEvent::SendClosingSigned, nodes[1].node.get_our_node_id());
                nodes[1].node.handle_closing_signed(&nodes[0].node.get_our_node_id(), &closing_signed_node_0);
                {
                        // Assert that the channel is kept in the `id_to_peer` map for both nodes until the
                        // channel can be fully closed by both parties (i.e. no outstanding htlcs exists, the
                        // fee for the closing transaction has been negotiated and the parties has the other
                        // party's signature for the fee negotiated closing transaction.)
                        let nodes_0_lock = nodes[0].node.id_to_peer.lock().unwrap();
                        assert_eq!(nodes_0_lock.len(), 1);
                        assert!(nodes_0_lock.contains_key(&channel_id));
                }

                {
                        // At this stage, `nodes[1]` has proposed a fee for the closing transaction in the
                        // `handle_closing_signed` call above. As `nodes[1]` has not yet received the signature
                        // from `nodes[0]` for the closing transaction with the proposed fee, the channel is
                        // kept in the `nodes[1]`'s `id_to_peer` map.
                        let nodes_1_lock = nodes[1].node.id_to_peer.lock().unwrap();
                        assert_eq!(nodes_1_lock.len(), 1);
                        assert!(nodes_1_lock.contains_key(&channel_id));
                }

                nodes[0].node.handle_closing_signed(&nodes[1].node.get_our_node_id(), &get_event_msg!(nodes[1], MessageSendEvent::SendClosingSigned, nodes[0].node.get_our_node_id()));
                {
                        // `nodes[0]` accepts `nodes[1]`'s proposed fee for the closing transaction, and
                        // therefore has all it needs to fully close the channel (both signatures for the
                        // closing transaction).
                        // Assert that the channel is removed from `nodes[0]`'s `id_to_peer` map as it can be
                        // fully closed by `nodes[0]`.
                        assert_eq!(nodes[0].node.id_to_peer.lock().unwrap().len(), 0);

                        // Assert that the channel is still in `nodes[1]`'s  `id_to_peer` map, as `nodes[1]`
                        // doesn't have `nodes[0]`'s signature for the closing transaction yet.
                        let nodes_1_lock = nodes[1].node.id_to_peer.lock().unwrap();
                        assert_eq!(nodes_1_lock.len(), 1);
                        assert!(nodes_1_lock.contains_key(&channel_id));
                }

                let (_nodes_0_update, closing_signed_node_0) = get_closing_signed_broadcast!(nodes[0].node, nodes[1].node.get_our_node_id());

                nodes[1].node.handle_closing_signed(&nodes[0].node.get_our_node_id(), &closing_signed_node_0.unwrap());
                {
                        // Assert that the channel has now been removed from both parties `id_to_peer` map once
                        // they both have everything required to fully close the channel.
                        assert_eq!(nodes[1].node.id_to_peer.lock().unwrap().len(), 0);
                }
                let (_nodes_1_update, _none) = get_closing_signed_broadcast!(nodes[1].node, nodes[0].node.get_our_node_id());

                check_closed_event!(nodes[0], 1, ClosureReason::CooperativeClosure, [nodes[1].node.get_our_node_id()], 1000000);
                check_closed_event!(nodes[1], 1, ClosureReason::CooperativeClosure, [nodes[0].node.get_our_node_id()], 1000000);
        }

        fn check_not_connected_to_peer_error<T>(res_err: Result<T, APIError>, expected_public_key: PublicKey) {
                let expected_message = format!("Not connected to node: {}", expected_public_key);
                check_api_error_message(expected_message, res_err)
        }

        fn check_unkown_peer_error<T>(res_err: Result<T, APIError>, expected_public_key: PublicKey) {
                let expected_message = format!("Can't find a peer matching the passed counterparty node_id {}", expected_public_key);
                check_api_error_message(expected_message, res_err)
        }

        fn check_channel_unavailable_error<T>(res_err: Result<T, APIError>, expected_channel_id: ChannelId, peer_node_id: PublicKey) {
                let expected_message = format!("Channel with id {} not found for the passed counterparty node_id {}", expected_channel_id, peer_node_id);
                check_api_error_message(expected_message, res_err)
        }

        fn check_api_misuse_error<T>(res_err: Result<T, APIError>) {
                let expected_message = "No such channel awaiting to be accepted.".to_string();
                check_api_error_message(expected_message, res_err)
        }

        fn check_api_error_message<T>(expected_err_message: String, res_err: Result<T, APIError>) {
                match res_err {
                        Err(APIError::APIMisuseError { err }) => {
                                assert_eq!(err, expected_err_message);
                        },
                        Err(APIError::ChannelUnavailable { err }) => {
                                assert_eq!(err, expected_err_message);
                        },
                        Ok(_) => panic!("Unexpected Ok"),
                        Err(_) => panic!("Unexpected Error"),
                }
        }

        #[test]
        fn test_api_calls_with_unkown_counterparty_node() {
                // Tests that our API functions that expects a `counterparty_node_id` as input, behaves as
                // expected if the `counterparty_node_id` is an unkown peer in the
                // `ChannelManager::per_peer_state` map.
                let chanmon_cfg = create_chanmon_cfgs(2);
                let node_cfg = create_node_cfgs(2, &chanmon_cfg);
                let node_chanmgr = create_node_chanmgrs(2, &node_cfg, &[None, None]);
                let nodes = create_network(2, &node_cfg, &node_chanmgr);

                // Dummy values
                let channel_id = ChannelId::from_bytes([4; 32]);
                let unkown_public_key = PublicKey::from_secret_key(&Secp256k1::signing_only(), &SecretKey::from_slice(&[42; 32]).unwrap());
                let intercept_id = InterceptId([0; 32]);

                // Test the API functions.
                check_not_connected_to_peer_error(nodes[0].node.create_channel(unkown_public_key, 1_000_000, 500_000_000, 42, None, None), unkown_public_key);

                check_unkown_peer_error(nodes[0].node.accept_inbound_channel(&channel_id, &unkown_public_key, 42), unkown_public_key);

                check_unkown_peer_error(nodes[0].node.close_channel(&channel_id, &unkown_public_key), unkown_public_key);

                check_unkown_peer_error(nodes[0].node.force_close_broadcasting_latest_txn(&channel_id, &unkown_public_key), unkown_public_key);

                check_unkown_peer_error(nodes[0].node.force_close_without_broadcasting_txn(&channel_id, &unkown_public_key), unkown_public_key);

                check_unkown_peer_error(nodes[0].node.forward_intercepted_htlc(intercept_id, &channel_id, unkown_public_key, 1_000_000), unkown_public_key);

                check_unkown_peer_error(nodes[0].node.update_channel_config(&unkown_public_key, &[channel_id], &ChannelConfig::default()), unkown_public_key);
        }

        #[test]
        fn test_api_calls_with_unavailable_channel() {
                // Tests that our API functions that expects a `counterparty_node_id` and a `channel_id`
                // as input, behaves as expected if the `counterparty_node_id` is a known peer in the
                // `ChannelManager::per_peer_state` map, but the peer state doesn't contain a channel with
                // the given `channel_id`.
                let chanmon_cfg = create_chanmon_cfgs(2);
                let node_cfg = create_node_cfgs(2, &chanmon_cfg);
                let node_chanmgr = create_node_chanmgrs(2, &node_cfg, &[None, None]);
                let nodes = create_network(2, &node_cfg, &node_chanmgr);

                let counterparty_node_id = nodes[1].node.get_our_node_id();

                // Dummy values
                let channel_id = ChannelId::from_bytes([4; 32]);

                // Test the API functions.
                check_api_misuse_error(nodes[0].node.accept_inbound_channel(&channel_id, &counterparty_node_id, 42));

                check_channel_unavailable_error(nodes[0].node.close_channel(&channel_id, &counterparty_node_id), channel_id, counterparty_node_id);

                check_channel_unavailable_error(nodes[0].node.force_close_broadcasting_latest_txn(&channel_id, &counterparty_node_id), channel_id, counterparty_node_id);

                check_channel_unavailable_error(nodes[0].node.force_close_without_broadcasting_txn(&channel_id, &counterparty_node_id), channel_id, counterparty_node_id);

                check_channel_unavailable_error(nodes[0].node.forward_intercepted_htlc(InterceptId([0; 32]), &channel_id, counterparty_node_id, 1_000_000), channel_id, counterparty_node_id);

                check_channel_unavailable_error(nodes[0].node.update_channel_config(&counterparty_node_id, &[channel_id], &ChannelConfig::default()), channel_id, counterparty_node_id);
        }

        #[test]
        fn test_connection_limiting() {
                // Test that we limit un-channel'd peers and un-funded channels properly.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                // Note that create_network connects the nodes together for us

                nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 42, None, None).unwrap();
                let mut open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());

                let mut funding_tx = None;
                for idx in 0..super::MAX_UNFUNDED_CHANS_PER_PEER {
                        nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                        let accept_channel = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());

                        if idx == 0 {
                                nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), &accept_channel);
                                let (temporary_channel_id, tx, _) = create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 100_000, 42);
                                funding_tx = Some(tx.clone());
                                nodes[0].node.funding_transaction_generated(&temporary_channel_id, &nodes[1].node.get_our_node_id(), tx).unwrap();
                                let funding_created_msg = get_event_msg!(nodes[0], MessageSendEvent::SendFundingCreated, nodes[1].node.get_our_node_id());

                                nodes[1].node.handle_funding_created(&nodes[0].node.get_our_node_id(), &funding_created_msg);
                                check_added_monitors!(nodes[1], 1);
                                expect_channel_pending_event(&nodes[1], &nodes[0].node.get_our_node_id());

                                let funding_signed = get_event_msg!(nodes[1], MessageSendEvent::SendFundingSigned, nodes[0].node.get_our_node_id());

                                nodes[0].node.handle_funding_signed(&nodes[1].node.get_our_node_id(), &funding_signed);
                                check_added_monitors!(nodes[0], 1);
                                expect_channel_pending_event(&nodes[0], &nodes[1].node.get_our_node_id());
                        }
                        open_channel_msg.temporary_channel_id = ChannelId::temporary_from_entropy_source(&nodes[0].keys_manager);
                }

                // A MAX_UNFUNDED_CHANS_PER_PEER + 1 channel will be summarily rejected
                open_channel_msg.temporary_channel_id = ChannelId::temporary_from_entropy_source(&nodes[0].keys_manager);
                nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                assert_eq!(get_err_msg(&nodes[1], &nodes[0].node.get_our_node_id()).channel_id,
                        open_channel_msg.temporary_channel_id);

                // Further, because all of our channels with nodes[0] are inbound, and none of them funded,
                // it doesn't count as a "protected" peer, i.e. it counts towards the MAX_NO_CHANNEL_PEERS
                // limit.
                let mut peer_pks = Vec::with_capacity(super::MAX_NO_CHANNEL_PEERS);
                for _ in 1..super::MAX_NO_CHANNEL_PEERS {
                        let random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
                                &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
                        peer_pks.push(random_pk);
                        nodes[1].node.peer_connected(&random_pk, &msgs::Init {
                                features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                        }, true).unwrap();
                }
                let last_random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
                        &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
                nodes[1].node.peer_connected(&last_random_pk, &msgs::Init {
                        features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                }, true).unwrap_err();

                // Also importantly, because nodes[0] isn't "protected", we will refuse a reconnection from
                // them if we have too many un-channel'd peers.
                nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());
                let chan_closed_events = nodes[1].node.get_and_clear_pending_events();
                assert_eq!(chan_closed_events.len(), super::MAX_UNFUNDED_CHANS_PER_PEER - 1);
                for ev in chan_closed_events {
                        if let Event::ChannelClosed { .. } = ev { } else { panic!(); }
                }
                nodes[1].node.peer_connected(&last_random_pk, &msgs::Init {
                        features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                }, true).unwrap();
                nodes[1].node.peer_connected(&nodes[0].node.get_our_node_id(), &msgs::Init {
                        features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                }, true).unwrap_err();

                // but of course if the connection is outbound its allowed...
                nodes[1].node.peer_connected(&nodes[0].node.get_our_node_id(), &msgs::Init {
                        features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                }, false).unwrap();
                nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());

                // Now nodes[0] is disconnected but still has a pending, un-funded channel lying around.
                // Even though we accept one more connection from new peers, we won't actually let them
                // open channels.
                assert!(peer_pks.len() > super::MAX_UNFUNDED_CHANNEL_PEERS - 1);
                for i in 0..super::MAX_UNFUNDED_CHANNEL_PEERS - 1 {
                        nodes[1].node.handle_open_channel(&peer_pks[i], &open_channel_msg);
                        get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, peer_pks[i]);
                        open_channel_msg.temporary_channel_id = ChannelId::temporary_from_entropy_source(&nodes[0].keys_manager);
                }
                nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
                assert_eq!(get_err_msg(&nodes[1], &last_random_pk).channel_id,
                        open_channel_msg.temporary_channel_id);

                // Of course, however, outbound channels are always allowed
                nodes[1].node.create_channel(last_random_pk, 100_000, 0, 42, None, None).unwrap();
                get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, last_random_pk);

                // If we fund the first channel, nodes[0] has a live on-chain channel with us, it is now
                // "protected" and can connect again.
                mine_transaction(&nodes[1], funding_tx.as_ref().unwrap());
                nodes[1].node.peer_connected(&nodes[0].node.get_our_node_id(), &msgs::Init {
                        features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                }, true).unwrap();
                get_event_msg!(nodes[1], MessageSendEvent::SendChannelReestablish, nodes[0].node.get_our_node_id());

                // Further, because the first channel was funded, we can open another channel with
                // last_random_pk.
                nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
                get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, last_random_pk);
        }

        #[test]
        fn test_outbound_chans_unlimited() {
                // Test that we never refuse an outbound channel even if a peer is unfuned-channel-limited
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                // Note that create_network connects the nodes together for us

                nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 42, None, None).unwrap();
                let mut open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());

                for _ in 0..super::MAX_UNFUNDED_CHANS_PER_PEER {
                        nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                        get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
                        open_channel_msg.temporary_channel_id = ChannelId::temporary_from_entropy_source(&nodes[0].keys_manager);
                }

                // Once we have MAX_UNFUNDED_CHANS_PER_PEER unfunded channels, new inbound channels will be
                // rejected.
                nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                assert_eq!(get_err_msg(&nodes[1], &nodes[0].node.get_our_node_id()).channel_id,
                        open_channel_msg.temporary_channel_id);

                // but we can still open an outbound channel.
                nodes[1].node.create_channel(nodes[0].node.get_our_node_id(), 100_000, 0, 42, None, None).unwrap();
                get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, nodes[0].node.get_our_node_id());

                // but even with such an outbound channel, additional inbound channels will still fail.
                nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                assert_eq!(get_err_msg(&nodes[1], &nodes[0].node.get_our_node_id()).channel_id,
                        open_channel_msg.temporary_channel_id);
        }

        #[test]
        fn test_0conf_limiting() {
                // Tests that we properly limit inbound channels when we have the manual-channel-acceptance
                // flag set and (sometimes) accept channels as 0conf.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let mut settings = test_default_channel_config();
                settings.manually_accept_inbound_channels = true;
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, Some(settings)]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                // Note that create_network connects the nodes together for us

                nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 42, None, None).unwrap();
                let mut open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());

                // First, get us up to MAX_UNFUNDED_CHANNEL_PEERS so we can test at the edge
                for _ in 0..super::MAX_UNFUNDED_CHANNEL_PEERS - 1 {
                        let random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
                                &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
                        nodes[1].node.peer_connected(&random_pk, &msgs::Init {
                                features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                        }, true).unwrap();

                        nodes[1].node.handle_open_channel(&random_pk, &open_channel_msg);
                        let events = nodes[1].node.get_and_clear_pending_events();
                        match events[0] {
                                Event::OpenChannelRequest { temporary_channel_id, .. } => {
                                        nodes[1].node.accept_inbound_channel(&temporary_channel_id, &random_pk, 23).unwrap();
                                }
                                _ => panic!("Unexpected event"),
                        }
                        get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, random_pk);
                        open_channel_msg.temporary_channel_id = ChannelId::temporary_from_entropy_source(&nodes[0].keys_manager);
                }

                // If we try to accept a channel from another peer non-0conf it will fail.
                let last_random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
                        &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
                nodes[1].node.peer_connected(&last_random_pk, &msgs::Init {
                        features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                }, true).unwrap();
                nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
                let events = nodes[1].node.get_and_clear_pending_events();
                match events[0] {
                        Event::OpenChannelRequest { temporary_channel_id, .. } => {
                                match nodes[1].node.accept_inbound_channel(&temporary_channel_id, &last_random_pk, 23) {
                                        Err(APIError::APIMisuseError { err }) =>
                                                assert_eq!(err, "Too many peers with unfunded channels, refusing to accept new ones"),
                                        _ => panic!(),
                                }
                        }
                        _ => panic!("Unexpected event"),
                }
                assert_eq!(get_err_msg(&nodes[1], &last_random_pk).channel_id,
                        open_channel_msg.temporary_channel_id);

                // ...however if we accept the same channel 0conf it should work just fine.
                nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
                let events = nodes[1].node.get_and_clear_pending_events();
                match events[0] {
                        Event::OpenChannelRequest { temporary_channel_id, .. } => {
                                nodes[1].node.accept_inbound_channel_from_trusted_peer_0conf(&temporary_channel_id, &last_random_pk, 23).unwrap();
                        }
                        _ => panic!("Unexpected event"),
                }
                get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, last_random_pk);
        }

        #[test]
        fn reject_excessively_underpaying_htlcs() {
                let chanmon_cfg = create_chanmon_cfgs(1);
                let node_cfg = create_node_cfgs(1, &chanmon_cfg);
                let node_chanmgr = create_node_chanmgrs(1, &node_cfg, &[None]);
                let node = create_network(1, &node_cfg, &node_chanmgr);
                let sender_intended_amt_msat = 100;
                let extra_fee_msat = 10;
                let hop_data = msgs::InboundOnionPayload::Receive {
                        amt_msat: 100,
                        outgoing_cltv_value: 42,
                        payment_metadata: None,
                        keysend_preimage: None,
                        payment_data: Some(msgs::FinalOnionHopData {
                                payment_secret: PaymentSecret([0; 32]), total_msat: sender_intended_amt_msat,
                        }),
                        custom_tlvs: Vec::new(),
                };
                // Check that if the amount we received + the penultimate hop extra fee is less than the sender
                // intended amount, we fail the payment.
                let current_height: u32 = node[0].node.best_block.read().unwrap().height();
                if let Err(crate::ln::channelmanager::InboundOnionErr { err_code, .. }) =
                        create_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
                                sender_intended_amt_msat - extra_fee_msat - 1, 42, None, true, Some(extra_fee_msat),
                                current_height, node[0].node.default_configuration.accept_mpp_keysend)
                {
                        assert_eq!(err_code, 19);
                } else { panic!(); }

                // If amt_received + extra_fee is equal to the sender intended amount, we're fine.
                let hop_data = msgs::InboundOnionPayload::Receive { // This is the same payload as above, InboundOnionPayload doesn't implement Clone
                        amt_msat: 100,
                        outgoing_cltv_value: 42,
                        payment_metadata: None,
                        keysend_preimage: None,
                        payment_data: Some(msgs::FinalOnionHopData {
                                payment_secret: PaymentSecret([0; 32]), total_msat: sender_intended_amt_msat,
                        }),
                        custom_tlvs: Vec::new(),
                };
                let current_height: u32 = node[0].node.best_block.read().unwrap().height();
                assert!(create_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
                        sender_intended_amt_msat - extra_fee_msat, 42, None, true, Some(extra_fee_msat),
                        current_height, node[0].node.default_configuration.accept_mpp_keysend).is_ok());
        }

        #[test]
        fn test_final_incorrect_cltv(){
                let chanmon_cfg = create_chanmon_cfgs(1);
                let node_cfg = create_node_cfgs(1, &chanmon_cfg);
                let node_chanmgr = create_node_chanmgrs(1, &node_cfg, &[None]);
                let node = create_network(1, &node_cfg, &node_chanmgr);

                let current_height: u32 = node[0].node.best_block.read().unwrap().height();
                let result = create_recv_pending_htlc_info(msgs::InboundOnionPayload::Receive {
                        amt_msat: 100,
                        outgoing_cltv_value: 22,
                        payment_metadata: None,
                        keysend_preimage: None,
                        payment_data: Some(msgs::FinalOnionHopData {
                                payment_secret: PaymentSecret([0; 32]), total_msat: 100,
                        }),
                        custom_tlvs: Vec::new(),
                }, [0; 32], PaymentHash([0; 32]), 100, 23, None, true, None, current_height,
                        node[0].node.default_configuration.accept_mpp_keysend);

                // Should not return an error as this condition:
                // https://github.com/lightning/bolts/blob/4dcc377209509b13cf89a4b91fde7d478f5b46d8/04-onion-routing.md?plain=1#L334
                // is not satisfied.
                assert!(result.is_ok());
        }

        #[test]
        fn test_inbound_anchors_manual_acceptance() {
                // Tests that we properly limit inbound channels when we have the manual-channel-acceptance
                // flag set and (sometimes) accept channels as 0conf.
                let mut anchors_cfg = test_default_channel_config();
                anchors_cfg.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx = true;

                let mut anchors_manual_accept_cfg = anchors_cfg.clone();
                anchors_manual_accept_cfg.manually_accept_inbound_channels = true;

                let chanmon_cfgs = create_chanmon_cfgs(3);
                let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs,
                        &[Some(anchors_cfg.clone()), Some(anchors_cfg.clone()), Some(anchors_manual_accept_cfg.clone())]);
                let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

                nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 42, None, None).unwrap();
                let open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());

                nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                assert!(nodes[1].node.get_and_clear_pending_events().is_empty());
                let msg_events = nodes[1].node.get_and_clear_pending_msg_events();
                match &msg_events[0] {
                        MessageSendEvent::HandleError { node_id, action } => {
                                assert_eq!(*node_id, nodes[0].node.get_our_node_id());
                                match action {
                                        ErrorAction::SendErrorMessage { msg } =>
                                                assert_eq!(msg.data, "No channels with anchor outputs accepted".to_owned()),
                                        _ => panic!("Unexpected error action"),
                                }
                        }
                        _ => panic!("Unexpected event"),
                }

                nodes[2].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                let events = nodes[2].node.get_and_clear_pending_events();
                match events[0] {
                        Event::OpenChannelRequest { temporary_channel_id, .. } =>
                                nodes[2].node.accept_inbound_channel(&temporary_channel_id, &nodes[0].node.get_our_node_id(), 23).unwrap(),
                        _ => panic!("Unexpected event"),
                }
                get_event_msg!(nodes[2], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
        }

        #[test]
        fn test_anchors_zero_fee_htlc_tx_fallback() {
                // Tests that if both nodes support anchors, but the remote node does not want to accept
                // anchor channels at the moment, an error it sent to the local node such that it can retry
                // the channel without the anchors feature.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let mut anchors_config = test_default_channel_config();
                anchors_config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx = true;
                anchors_config.manually_accept_inbound_channels = true;
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[Some(anchors_config.clone()), Some(anchors_config.clone())]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 0, None, None).unwrap();
                let open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
                assert!(open_channel_msg.channel_type.as_ref().unwrap().supports_anchors_zero_fee_htlc_tx());

                nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
                let events = nodes[1].node.get_and_clear_pending_events();
                match events[0] {
                        Event::OpenChannelRequest { temporary_channel_id, .. } => {
                                nodes[1].node.force_close_broadcasting_latest_txn(&temporary_channel_id, &nodes[0].node.get_our_node_id()).unwrap();
                        }
                        _ => panic!("Unexpected event"),
                }

                let error_msg = get_err_msg(&nodes[1], &nodes[0].node.get_our_node_id());
                nodes[0].node.handle_error(&nodes[1].node.get_our_node_id(), &error_msg);

                let open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
                assert!(!open_channel_msg.channel_type.unwrap().supports_anchors_zero_fee_htlc_tx());

                // Since nodes[1] should not have accepted the channel, it should
                // not have generated any events.
                assert!(nodes[1].node.get_and_clear_pending_events().is_empty());
        }

        #[test]
        fn test_update_channel_config() {
                let chanmon_cfg = create_chanmon_cfgs(2);
                let node_cfg = create_node_cfgs(2, &chanmon_cfg);
                let mut user_config = test_default_channel_config();
                let node_chanmgr = create_node_chanmgrs(2, &node_cfg, &[Some(user_config), Some(user_config)]);
                let nodes = create_network(2, &node_cfg, &node_chanmgr);
                let _ = create_announced_chan_between_nodes(&nodes, 0, 1);
                let channel = &nodes[0].node.list_channels()[0];

                nodes[0].node.update_channel_config(&channel.counterparty.node_id, &[channel.channel_id], &user_config.channel_config).unwrap();
                let events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 0);

                user_config.channel_config.forwarding_fee_base_msat += 10;
                nodes[0].node.update_channel_config(&channel.counterparty.node_id, &[channel.channel_id], &user_config.channel_config).unwrap();
                assert_eq!(nodes[0].node.list_channels()[0].config.unwrap().forwarding_fee_base_msat, user_config.channel_config.forwarding_fee_base_msat);
                let events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                match &events[0] {
                        MessageSendEvent::BroadcastChannelUpdate { .. } => {},
                        _ => panic!("expected BroadcastChannelUpdate event"),
                }

                nodes[0].node.update_partial_channel_config(&channel.counterparty.node_id, &[channel.channel_id], &ChannelConfigUpdate::default()).unwrap();
                let events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 0);

                let new_cltv_expiry_delta = user_config.channel_config.cltv_expiry_delta + 6;
                nodes[0].node.update_partial_channel_config(&channel.counterparty.node_id, &[channel.channel_id], &ChannelConfigUpdate {
                        cltv_expiry_delta: Some(new_cltv_expiry_delta),
                        ..Default::default()
                }).unwrap();
                assert_eq!(nodes[0].node.list_channels()[0].config.unwrap().cltv_expiry_delta, new_cltv_expiry_delta);
                let events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                match &events[0] {
                        MessageSendEvent::BroadcastChannelUpdate { .. } => {},
                        _ => panic!("expected BroadcastChannelUpdate event"),
                }

                let new_fee = user_config.channel_config.forwarding_fee_proportional_millionths + 100;
                nodes[0].node.update_partial_channel_config(&channel.counterparty.node_id, &[channel.channel_id], &ChannelConfigUpdate {
                        forwarding_fee_proportional_millionths: Some(new_fee),
                        ..Default::default()
                }).unwrap();
                assert_eq!(nodes[0].node.list_channels()[0].config.unwrap().cltv_expiry_delta, new_cltv_expiry_delta);
                assert_eq!(nodes[0].node.list_channels()[0].config.unwrap().forwarding_fee_proportional_millionths, new_fee);
                let events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 1);
                match &events[0] {
                        MessageSendEvent::BroadcastChannelUpdate { .. } => {},
                        _ => panic!("expected BroadcastChannelUpdate event"),
                }

                // If we provide a channel_id not associated with the peer, we should get an error and no updates
                // should be applied to ensure update atomicity as specified in the API docs.
                let bad_channel_id = ChannelId::v1_from_funding_txid(&[10; 32], 10);
                let current_fee = nodes[0].node.list_channels()[0].config.unwrap().forwarding_fee_proportional_millionths;
                let new_fee = current_fee + 100;
                assert!(
                        matches!(
                                nodes[0].node.update_partial_channel_config(&channel.counterparty.node_id, &[channel.channel_id, bad_channel_id], &ChannelConfigUpdate {
                                        forwarding_fee_proportional_millionths: Some(new_fee),
                                        ..Default::default()
                                }),
                                Err(APIError::ChannelUnavailable { err: _ }),
                        )
                );
                // Check that the fee hasn't changed for the channel that exists.
                assert_eq!(nodes[0].node.list_channels()[0].config.unwrap().forwarding_fee_proportional_millionths, current_fee);
                let events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(events.len(), 0);
        }

        #[test]
        fn test_payment_display() {
                let payment_id = PaymentId([42; 32]);
                assert_eq!(format!("{}", &payment_id), "2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a");
                let payment_hash = PaymentHash([42; 32]);
                assert_eq!(format!("{}", &payment_hash), "2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a");
                let payment_preimage = PaymentPreimage([42; 32]);
                assert_eq!(format!("{}", &payment_preimage), "2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a");
        }

        #[test]
        fn test_trigger_lnd_force_close() {
                let chanmon_cfg = create_chanmon_cfgs(2);
                let node_cfg = create_node_cfgs(2, &chanmon_cfg);
                let user_config = test_default_channel_config();
                let node_chanmgr = create_node_chanmgrs(2, &node_cfg, &[Some(user_config), Some(user_config)]);
                let nodes = create_network(2, &node_cfg, &node_chanmgr);

                // Open a channel, immediately disconnect each other, and broadcast Alice's latest state.
                let (_, _, chan_id, funding_tx) = create_announced_chan_between_nodes(&nodes, 0, 1);
                nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id());
                nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());
                nodes[0].node.force_close_broadcasting_latest_txn(&chan_id, &nodes[1].node.get_our_node_id()).unwrap();
                check_closed_broadcast(&nodes[0], 1, true);
                check_added_monitors(&nodes[0], 1);
                check_closed_event!(nodes[0], 1, ClosureReason::HolderForceClosed, [nodes[1].node.get_our_node_id()], 100000);
                {
                        let txn = nodes[0].tx_broadcaster.txn_broadcast();
                        assert_eq!(txn.len(), 1);
                        check_spends!(txn[0], funding_tx);
                }

                // Since they're disconnected, Bob won't receive Alice's `Error` message. Reconnect them
                // such that Bob sends a `ChannelReestablish` to Alice since the channel is still open from
                // their side.
                nodes[0].node.peer_connected(&nodes[1].node.get_our_node_id(), &msgs::Init {
                        features: nodes[1].node.init_features(), networks: None, remote_network_address: None
                }, true).unwrap();
                nodes[1].node.peer_connected(&nodes[0].node.get_our_node_id(), &msgs::Init {
                        features: nodes[0].node.init_features(), networks: None, remote_network_address: None
                }, false).unwrap();
                assert!(nodes[0].node.get_and_clear_pending_msg_events().is_empty());
                let channel_reestablish = get_event_msg!(
                        nodes[1], MessageSendEvent::SendChannelReestablish, nodes[0].node.get_our_node_id()
                );
                nodes[0].node.handle_channel_reestablish(&nodes[1].node.get_our_node_id(), &channel_reestablish);

                // Alice should respond with an error since the channel isn't known, but a bogus
                // `ChannelReestablish` should be sent first, such that we actually trigger Bob to force
                // close even if it was an lnd node.
                let msg_events = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(msg_events.len(), 2);
                if let MessageSendEvent::SendChannelReestablish { node_id, msg } = &msg_events[0] {
                        assert_eq!(*node_id, nodes[1].node.get_our_node_id());
                        assert_eq!(msg.next_local_commitment_number, 0);
                        assert_eq!(msg.next_remote_commitment_number, 0);
                        nodes[1].node.handle_channel_reestablish(&nodes[0].node.get_our_node_id(), &msg);
                } else { panic!() };
                check_closed_broadcast(&nodes[1], 1, true);
                check_added_monitors(&nodes[1], 1);
                let expected_close_reason = ClosureReason::ProcessingError {
                        err: "Peer sent an invalid channel_reestablish to force close in a non-standard way".to_string()
                };
                check_closed_event!(nodes[1], 1, expected_close_reason, [nodes[0].node.get_our_node_id()], 100000);
                {
                        let txn = nodes[1].tx_broadcaster.txn_broadcast();
                        assert_eq!(txn.len(), 1);
                        check_spends!(txn[0], funding_tx);
                }
        }

        #[test]
        fn test_peel_payment_onion() {
                use super::*;
                let secp_ctx = Secp256k1::new();

                let bob = crate::sign::KeysManager::new(&[2; 32], 42, 42);
                let bob_pk = PublicKey::from_secret_key(&secp_ctx, &bob.get_node_secret_key());
                let charlie = crate::sign::KeysManager::new(&[3; 32], 42, 42);
                let charlie_pk = PublicKey::from_secret_key(&secp_ctx, &charlie.get_node_secret_key());

                let (session_priv, total_amt_msat, cur_height, recipient_onion, preimage, payment_hash,
                        prng_seed, hops, recipient_amount, pay_secret) = payment_onion_args(bob_pk, charlie_pk);

                let path = Path {
                        hops: hops,
                        blinded_tail: None,
                };

                let (amount_msat, cltv_expiry, onion) = create_payment_onion(
                        &secp_ctx, &path, &session_priv, total_amt_msat, recipient_onion, cur_height,
                        payment_hash, Some(preimage), prng_seed
                ).unwrap();

                let msg = make_update_add_msg(amount_msat, cltv_expiry, payment_hash, onion);
                let logger = test_utils::TestLogger::with_id("bob".to_string());

                let peeled = peel_payment_onion(&msg, &&bob, &&logger, &secp_ctx, cur_height, true)
                        .map_err(|e| e.msg).unwrap();

                let next_onion = match peeled.routing {
                        PendingHTLCRouting::Forward { onion_packet, short_channel_id: _ } => {
                                onion_packet
                        },
                        _ => panic!("expected a forwarded onion"),
                };

                let msg2 = make_update_add_msg(amount_msat, cltv_expiry, payment_hash, next_onion);
                let peeled2 = peel_payment_onion(&msg2, &&charlie, &&logger, &secp_ctx, cur_height, true)
                        .map_err(|e| e.msg).unwrap();

                match peeled2.routing {
                        PendingHTLCRouting::ReceiveKeysend { payment_preimage, payment_data, incoming_cltv_expiry, .. } => {
                                assert_eq!(payment_preimage, preimage);
                                assert_eq!(peeled2.outgoing_amt_msat, recipient_amount);
                                assert_eq!(incoming_cltv_expiry, peeled2.outgoing_cltv_value);
                                let msgs::FinalOnionHopData{total_msat, payment_secret} = payment_data.unwrap();
                                assert_eq!(total_msat, total_amt_msat);
                                assert_eq!(payment_secret, pay_secret);
                        },
                        _ => panic!("expected a received keysend"),
                };
        }

        fn make_update_add_msg(
                amount_msat: u64, cltv_expiry: u32, payment_hash: PaymentHash,
                onion_routing_packet: msgs::OnionPacket
        ) -> msgs::UpdateAddHTLC {
                msgs::UpdateAddHTLC {
                        channel_id: ChannelId::from_bytes([0; 32]),
                        htlc_id: 0,
                        amount_msat,
                        cltv_expiry,
                        payment_hash,
                        onion_routing_packet,
                        skimmed_fee_msat: None,
                }
        }

        fn payment_onion_args(hop_pk: PublicKey, recipient_pk: PublicKey) -> (
                SecretKey, u64, u32, RecipientOnionFields, PaymentPreimage, PaymentHash, [u8; 32],
                Vec<RouteHop>, u64, PaymentSecret,
        ) {
                let session_priv_bytes = [42; 32];
                let session_priv = SecretKey::from_slice(&session_priv_bytes).unwrap();
                let total_amt_msat = 1000;
                let cur_height = 1000;
                let pay_secret = PaymentSecret([99; 32]);
                let recipient_onion = RecipientOnionFields::secret_only(pay_secret);
                let preimage_bytes = [43; 32];
                let preimage = PaymentPreimage(preimage_bytes);
                let rhash_bytes = Sha256::hash(&preimage_bytes).to_byte_array();
                let payment_hash = PaymentHash(rhash_bytes);
                let prng_seed = [44; 32];

                // make a route alice -> bob -> charlie
                let hop_fee = 1;
                let recipient_amount = total_amt_msat - hop_fee;
                let hops = vec![
                        RouteHop {
                                pubkey: hop_pk,
                                fee_msat: hop_fee,
                                cltv_expiry_delta: 42,
                                short_channel_id: 1,
                                node_features: NodeFeatures::empty(),
                                channel_features: ChannelFeatures::empty(),
                                maybe_announced_channel: false,
                        },
                        RouteHop {
                                pubkey: recipient_pk,
                                fee_msat: recipient_amount,
                                cltv_expiry_delta: 42,
                                short_channel_id: 2,
                                node_features: NodeFeatures::empty(),
                                channel_features: ChannelFeatures::empty(),
                                maybe_announced_channel: false,
                        }
                ];

                (session_priv, total_amt_msat, cur_height, recipient_onion, preimage, payment_hash,
                        prng_seed, hops, recipient_amount, pay_secret)
        }

        pub fn create_payment_onion<T: bitcoin::secp256k1::Signing>(
                secp_ctx: &Secp256k1<T>, path: &Path, session_priv: &SecretKey, total_msat: u64,
                recipient_onion: RecipientOnionFields, best_block_height: u32, payment_hash: PaymentHash,
                keysend_preimage: Option<PaymentPreimage>, prng_seed: [u8; 32]
        ) -> Result<(u64, u32, msgs::OnionPacket), ()> {
                let onion_keys = super::onion_utils::construct_onion_keys(&secp_ctx, &path, &session_priv).map_err(|_| ())?;
                let (onion_payloads, htlc_msat, htlc_cltv) = super::onion_utils::build_onion_payloads(
                        &path,
                        total_msat,
                        recipient_onion,
                        best_block_height + 1,
                        &keysend_preimage,
                ).map_err(|_| ())?;
                let onion_packet = super::onion_utils::construct_onion_packet(
                        onion_payloads, onion_keys, prng_seed, &payment_hash
                )?;
                Ok((htlc_msat, htlc_cltv, onion_packet))
        }
}

#[cfg(ldk_bench)]
pub mod bench {
        use crate::chain::Listen;
        use crate::chain::chainmonitor::{ChainMonitor, Persist};
        use crate::sign::{KeysManager, InMemorySigner};
        use crate::events::{Event, MessageSendEvent, MessageSendEventsProvider};
        use crate::ln::channelmanager::{BestBlock, ChainParameters, ChannelManager, PaymentHash, PaymentPreimage, PaymentId, RecipientOnionFields, Retry};
        use crate::ln::functional_test_utils::*;
        use crate::ln::msgs::{ChannelMessageHandler, Init};
        use crate::routing::gossip::NetworkGraph;
        use crate::routing::router::{PaymentParameters, RouteParameters};
        use crate::util::test_utils;
        use crate::util::config::{UserConfig, MaxDustHTLCExposure};

        use bitcoin::blockdata::locktime::absolute::LockTime;
        use bitcoin::hashes::Hash;
        use bitcoin::hashes::sha256::Hash as Sha256;
        use bitcoin::{Block, Transaction, TxOut};

        use crate::sync::{Arc, Mutex, RwLock};

        use criterion::Criterion;

        type Manager<'a, P> = ChannelManager<
                &'a ChainMonitor<InMemorySigner, &'a test_utils::TestChainSource,
                        &'a test_utils::TestBroadcaster, &'a test_utils::TestFeeEstimator,
                        &'a test_utils::TestLogger, &'a P>,
                &'a test_utils::TestBroadcaster, &'a KeysManager, &'a KeysManager, &'a KeysManager,
                &'a test_utils::TestFeeEstimator, &'a test_utils::TestRouter<'a>,
                &'a test_utils::TestLogger>;

        struct ANodeHolder<'node_cfg, 'chan_mon_cfg: 'node_cfg, P: Persist<InMemorySigner>> {
                node: &'node_cfg Manager<'chan_mon_cfg, P>,
        }
        impl<'node_cfg, 'chan_mon_cfg: 'node_cfg, P: Persist<InMemorySigner>> NodeHolder for ANodeHolder<'node_cfg, 'chan_mon_cfg, P> {
                type CM = Manager<'chan_mon_cfg, P>;
                #[inline]
                fn node(&self) -> &Manager<'chan_mon_cfg, P> { self.node }
                #[inline]
                fn chain_monitor(&self) -> Option<&test_utils::TestChainMonitor> { None }
        }

        pub fn bench_sends(bench: &mut Criterion) {
                bench_two_sends(bench, "bench_sends", test_utils::TestPersister::new(), test_utils::TestPersister::new());
        }

        pub fn bench_two_sends<P: Persist<InMemorySigner>>(bench: &mut Criterion, bench_name: &str, persister_a: P, persister_b: P) {
                // Do a simple benchmark of sending a payment back and forth between two nodes.
                // Note that this is unrealistic as each payment send will require at least two fsync
                // calls per node.
                let network = bitcoin::Network::Testnet;
                let genesis_block = bitcoin::blockdata::constants::genesis_block(network);

                let tx_broadcaster = test_utils::TestBroadcaster::new(network);
                let fee_estimator = test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) };
                let logger_a = test_utils::TestLogger::with_id("node a".to_owned());
                let scorer = RwLock::new(test_utils::TestScorer::new());
                let router = test_utils::TestRouter::new(Arc::new(NetworkGraph::new(network, &logger_a)), &scorer);

                let mut config: UserConfig = Default::default();
                config.channel_config.max_dust_htlc_exposure = MaxDustHTLCExposure::FeeRateMultiplier(5_000_000 / 253);
                config.channel_handshake_config.minimum_depth = 1;

                let chain_monitor_a = ChainMonitor::new(None, &tx_broadcaster, &logger_a, &fee_estimator, &persister_a);
                let seed_a = [1u8; 32];
                let keys_manager_a = KeysManager::new(&seed_a, 42, 42);
                let node_a = ChannelManager::new(&fee_estimator, &chain_monitor_a, &tx_broadcaster, &router, &logger_a, &keys_manager_a, &keys_manager_a, &keys_manager_a, config.clone(), ChainParameters {
                        network,
                        best_block: BestBlock::from_network(network),
                }, genesis_block.header.time);
                let node_a_holder = ANodeHolder { node: &node_a };

                let logger_b = test_utils::TestLogger::with_id("node a".to_owned());
                let chain_monitor_b = ChainMonitor::new(None, &tx_broadcaster, &logger_a, &fee_estimator, &persister_b);
                let seed_b = [2u8; 32];
                let keys_manager_b = KeysManager::new(&seed_b, 42, 42);
                let node_b = ChannelManager::new(&fee_estimator, &chain_monitor_b, &tx_broadcaster, &router, &logger_b, &keys_manager_b, &keys_manager_b, &keys_manager_b, config.clone(), ChainParameters {
                        network,
                        best_block: BestBlock::from_network(network),
                }, genesis_block.header.time);
                let node_b_holder = ANodeHolder { node: &node_b };

                node_a.peer_connected(&node_b.get_our_node_id(), &Init {
                        features: node_b.init_features(), networks: None, remote_network_address: None
                }, true).unwrap();
                node_b.peer_connected(&node_a.get_our_node_id(), &Init {
                        features: node_a.init_features(), networks: None, remote_network_address: None
                }, false).unwrap();
                node_a.create_channel(node_b.get_our_node_id(), 8_000_000, 100_000_000, 42, None, None).unwrap();
                node_b.handle_open_channel(&node_a.get_our_node_id(), &get_event_msg!(node_a_holder, MessageSendEvent::SendOpenChannel, node_b.get_our_node_id()));
                node_a.handle_accept_channel(&node_b.get_our_node_id(), &get_event_msg!(node_b_holder, MessageSendEvent::SendAcceptChannel, node_a.get_our_node_id()));

                let tx;
                if let Event::FundingGenerationReady { temporary_channel_id, output_script, .. } = get_event!(node_a_holder, Event::FundingGenerationReady) {
                        tx = Transaction { version: 2, lock_time: LockTime::ZERO, input: Vec::new(), output: vec![TxOut {
                                value: 8_000_000, script_pubkey: output_script,
                        }]};
                        node_a.funding_transaction_generated(&temporary_channel_id, &node_b.get_our_node_id(), tx.clone()).unwrap();
                } else { panic!(); }

                node_b.handle_funding_created(&node_a.get_our_node_id(), &get_event_msg!(node_a_holder, MessageSendEvent::SendFundingCreated, node_b.get_our_node_id()));
                let events_b = node_b.get_and_clear_pending_events();
                assert_eq!(events_b.len(), 1);
                match events_b[0] {
                        Event::ChannelPending{ ref counterparty_node_id, .. } => {
                                assert_eq!(*counterparty_node_id, node_a.get_our_node_id());
                        },
                        _ => panic!("Unexpected event"),
                }

                node_a.handle_funding_signed(&node_b.get_our_node_id(), &get_event_msg!(node_b_holder, MessageSendEvent::SendFundingSigned, node_a.get_our_node_id()));
                let events_a = node_a.get_and_clear_pending_events();
                assert_eq!(events_a.len(), 1);
                match events_a[0] {
                        Event::ChannelPending{ ref counterparty_node_id, .. } => {
                                assert_eq!(*counterparty_node_id, node_b.get_our_node_id());
                        },
                        _ => panic!("Unexpected event"),
                }

                assert_eq!(&tx_broadcaster.txn_broadcasted.lock().unwrap()[..], &[tx.clone()]);

                let block = create_dummy_block(BestBlock::from_network(network).block_hash(), 42, vec![tx]);
                Listen::block_connected(&node_a, &block, 1);
                Listen::block_connected(&node_b, &block, 1);

                node_a.handle_channel_ready(&node_b.get_our_node_id(), &get_event_msg!(node_b_holder, MessageSendEvent::SendChannelReady, node_a.get_our_node_id()));
                let msg_events = node_a.get_and_clear_pending_msg_events();
                assert_eq!(msg_events.len(), 2);
                match msg_events[0] {
                        MessageSendEvent::SendChannelReady { ref msg, .. } => {
                                node_b.handle_channel_ready(&node_a.get_our_node_id(), msg);
                                get_event_msg!(node_b_holder, MessageSendEvent::SendChannelUpdate, node_a.get_our_node_id());
                        },
                        _ => panic!(),
                }
                match msg_events[1] {
                        MessageSendEvent::SendChannelUpdate { .. } => {},
                        _ => panic!(),
                }

                let events_a = node_a.get_and_clear_pending_events();
                assert_eq!(events_a.len(), 1);
                match events_a[0] {
                        Event::ChannelReady{ ref counterparty_node_id, .. } => {
                                assert_eq!(*counterparty_node_id, node_b.get_our_node_id());
                        },
                        _ => panic!("Unexpected event"),
                }

                let events_b = node_b.get_and_clear_pending_events();
                assert_eq!(events_b.len(), 1);
                match events_b[0] {
                        Event::ChannelReady{ ref counterparty_node_id, .. } => {
                                assert_eq!(*counterparty_node_id, node_a.get_our_node_id());
                        },
                        _ => panic!("Unexpected event"),
                }

                let mut payment_count: u64 = 0;
                macro_rules! send_payment {
                        ($node_a: expr, $node_b: expr) => {
                                let payment_params = PaymentParameters::from_node_id($node_b.get_our_node_id(), TEST_FINAL_CLTV)
                                        .with_bolt11_features($node_b.bolt11_invoice_features()).unwrap();
                                let mut payment_preimage = PaymentPreimage([0; 32]);
                                payment_preimage.0[0..8].copy_from_slice(&payment_count.to_le_bytes());
                                payment_count += 1;
                                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0[..]).to_byte_array());
                                let payment_secret = $node_b.create_inbound_payment_for_hash(payment_hash, None, 7200, None).unwrap();

                                $node_a.send_payment(payment_hash, RecipientOnionFields::secret_only(payment_secret),
                                        PaymentId(payment_hash.0),
                                        RouteParameters::from_payment_params_and_value(payment_params, 10_000),
                                        Retry::Attempts(0)).unwrap();
                                let payment_event = SendEvent::from_event($node_a.get_and_clear_pending_msg_events().pop().unwrap());
                                $node_b.handle_update_add_htlc(&$node_a.get_our_node_id(), &payment_event.msgs[0]);
                                $node_b.handle_commitment_signed(&$node_a.get_our_node_id(), &payment_event.commitment_msg);
                                let (raa, cs) = get_revoke_commit_msgs(&ANodeHolder { node: &$node_b }, &$node_a.get_our_node_id());
                                $node_a.handle_revoke_and_ack(&$node_b.get_our_node_id(), &raa);
                                $node_a.handle_commitment_signed(&$node_b.get_our_node_id(), &cs);
                                $node_b.handle_revoke_and_ack(&$node_a.get_our_node_id(), &get_event_msg!(ANodeHolder { node: &$node_a }, MessageSendEvent::SendRevokeAndACK, $node_b.get_our_node_id()));

                                expect_pending_htlcs_forwardable!(ANodeHolder { node: &$node_b });
                                expect_payment_claimable!(ANodeHolder { node: &$node_b }, payment_hash, payment_secret, 10_000);
                                $node_b.claim_funds(payment_preimage);
                                expect_payment_claimed!(ANodeHolder { node: &$node_b }, payment_hash, 10_000);

                                match $node_b.get_and_clear_pending_msg_events().pop().unwrap() {
                                        MessageSendEvent::UpdateHTLCs { node_id, updates } => {
                                                assert_eq!(node_id, $node_a.get_our_node_id());
                                                $node_a.handle_update_fulfill_htlc(&$node_b.get_our_node_id(), &updates.update_fulfill_htlcs[0]);
                                                $node_a.handle_commitment_signed(&$node_b.get_our_node_id(), &updates.commitment_signed);
                                        },
                                        _ => panic!("Failed to generate claim event"),
                                }

                                let (raa, cs) = get_revoke_commit_msgs(&ANodeHolder { node: &$node_a }, &$node_b.get_our_node_id());
                                $node_b.handle_revoke_and_ack(&$node_a.get_our_node_id(), &raa);
                                $node_b.handle_commitment_signed(&$node_a.get_our_node_id(), &cs);
                                $node_a.handle_revoke_and_ack(&$node_b.get_our_node_id(), &get_event_msg!(ANodeHolder { node: &$node_b }, MessageSendEvent::SendRevokeAndACK, $node_a.get_our_node_id()));

                                expect_payment_sent!(ANodeHolder { node: &$node_a }, payment_preimage);
                        }
                }

                bench.bench_function(bench_name, |b| b.iter(|| {
                        send_payment!(node_a, node_b);
                        send_payment!(node_b, node_a);
                }));
        }
}