[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 [`find_route`] 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).
//!
//! [`find_route`]: crate::routing::router::find_route

use bitcoin::blockdata::block::BlockHeader;
use bitcoin::blockdata::transaction::Transaction;
use bitcoin::blockdata::constants::genesis_block;
use bitcoin::network::constants::Network;

use bitcoin::hashes::Hash;
use bitcoin::hashes::sha256::Hash as Sha256;
use bitcoin::hashes::sha256d::Hash as Sha256dHash;
use bitcoin::hash_types::{BlockHash, Txid};

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

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};
// 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, PaymentHash, PaymentPreimage, PaymentSecret};
use crate::ln::channel::{Channel, ChannelError, ChannelUpdateStatus, UpdateFulfillCommitFetch};
use crate::ln::features::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
#[cfg(any(feature = "_test_utils", test))]
use crate::ln::features::InvoiceFeatures;
use crate::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, RoutePath, RouteParameters};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::HTLCFailReason;
use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError, MAX_VALUE_MSAT};
use crate::ln::outbound_payment::PendingOutboundPayment;
use crate::ln::wire::Encode;
use crate::chain::keysinterface::{Sign, KeysInterface, KeysManager, Recipient};
use crate::util::config::{UserConfig, ChannelConfig};
use crate::util::events::{Event, EventHandler, EventsProvider, MessageSendEvent, MessageSendEventsProvider, ClosureReason, HTLCDestination};
use crate::util::events;
use crate::util::wakers::{Future, Notifier};
use crate::util::scid_utils::fake_scid;
use crate::util::ser::{BigSize, FixedLengthReader, Readable, ReadableArgs, MaybeReadable, Writeable, Writer, VecWriter};
use crate::util::logger::{Level, Logger};
use crate::util::errors::APIError;

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

// 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.

#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub(super) enum PendingHTLCRouting {
        Forward {
                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
        },
        Receive {
                payment_data: msgs::FinalOnionHopData,
                incoming_cltv_expiry: u32, // Used to track when we should expire pending HTLCs that go unclaimed
                phantom_shared_secret: Option<[u8; 32]>,
        },
        ReceiveKeysend {
                payment_preimage: PaymentPreimage,
                incoming_cltv_expiry: u32, // Used to track when we should expire pending HTLCs that go unclaimed
        },
}

#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub(super) struct PendingHTLCInfo {
        pub(super) routing: PendingHTLCRouting,
        pub(super) incoming_shared_secret: [u8; 32],
        payment_hash: PaymentHash,
        pub(super) incoming_amt_msat: Option<u64>, // Added in 0.0.113
        pub(super) outgoing_amt_msat: u64,
        pub(super) outgoing_cltv_value: u32,
}

#[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, Hash, PartialEq, Eq)]
pub(crate) struct HTLCPreviousHopData {
        // Note that this may be an outbound SCID alias for the associated channel.
        short_channel_id: u64,
        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,
        onion_payload: OnionPayload,
        timer_ticks: u8,
        /// The sum total of all MPP parts
        total_msat: u64,
}

/// A payment identifier used to uniquely identify a payment to LDK.
/// (C-not exported) as we just use [u8; 32] directly
#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
pub struct PaymentId(pub [u8; 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))
        }
}

/// An identifier used to uniquely identify an intercepted HTLC to LDK.
/// (C-not exported) 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))
        }
}
/// 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, PartialEq, Eq)]
pub(crate) enum HTLCSource {
        PreviousHopData(HTLCPreviousHopData),
        OutboundRoute {
                path: Vec<RouteHop>,
                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,
                payment_secret: Option<PaymentSecret>,
                payment_params: Option<PaymentParameters>,
        },
}
#[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, payment_secret, first_hop_htlc_msat, payment_params } => {
                                1u8.hash(hasher);
                                path.hash(hasher);
                                session_priv[..].hash(hasher);
                                payment_id.hash(hasher);
                                payment_secret.hash(hasher);
                                first_hop_htlc_msat.hash(hasher);
                                payment_params.hash(hasher);
                        },
                }
        }
}
#[cfg(not(feature = "grind_signatures"))]
#[cfg(test)]
impl HTLCSource {
        pub fn dummy() -> Self {
                HTLCSource::OutboundRoute {
                        path: Vec::new(),
                        session_priv: SecretKey::from_slice(&[1; 32]).unwrap(),
                        first_hop_htlc_msat: 0,
                        payment_id: PaymentId([2; 32]),
                        payment_secret: None,
                        payment_params: None,
                }
        }
}

struct ReceiveError {
        err_code: u16,
        err_data: Vec<u8>,
        msg: &'static str,
}

type ShutdownResult = (Option<(OutPoint, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash, PublicKey, [u8; 32])>);

/// Error type returned across the channel_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
/// channel_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<([u8; 32], u128)>, // If Some a channel of ours has been closed
        shutdown_finish: Option<(ShutdownResult, Option<msgs::ChannelUpdate>)>,
}
impl MsgHandleErrInternal {
        #[inline]
        fn send_err_msg_no_close(err: String, channel_id: [u8; 32]) -> Self {
                Self {
                        err: LightningError {
                                err: err.clone(),
                                action: msgs::ErrorAction::SendErrorMessage {
                                        msg: msgs::ErrorMessage {
                                                channel_id,
                                                data: err
                                        },
                                },
                        },
                        chan_id: None,
                        shutdown_finish: None,
                }
        }
        #[inline]
        fn ignore_no_close(err: String) -> Self {
                Self {
                        err: LightningError {
                                err,
                                action: msgs::ErrorAction::IgnoreError,
                        },
                        chan_id: None,
                        shutdown_finish: None,
                }
        }
        #[inline]
        fn from_no_close(err: msgs::LightningError) -> Self {
                Self { err, chan_id: None, shutdown_finish: None }
        }
        #[inline]
        fn from_finish_shutdown(err: String, channel_id: [u8; 32], user_channel_id: u128, shutdown_res: ShutdownResult, channel_update: Option<msgs::ChannelUpdate>) -> Self {
                Self {
                        err: LightningError {
                                err: err.clone(),
                                action: msgs::ErrorAction::SendErrorMessage {
                                        msg: msgs::ErrorMessage {
                                                channel_id,
                                                data: err
                                        },
                                },
                        },
                        chan_id: Some((channel_id, user_channel_id)),
                        shutdown_finish: Some((shutdown_res, channel_update)),
                }
        }
        #[inline]
        fn from_chan_no_close(err: ChannelError, channel_id: [u8; 32]) -> 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,
                }
        }
}

/// 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.
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,
}
impl_writeable_tlv_based!(ClaimingPayment, {
        (0, amount_msat, required),
        (2, payment_purpose, required),
        (4, receiver_node_id, required),
});

/// 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_htlcs: HashMap<PaymentHash, (events::PaymentPurpose, Vec<ClaimableHTLC>)>,

        /// 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>,
}

// Note this is only exposed in cfg(test):
pub(super) struct ChannelHolder<Signer: Sign> {
        pub(super) by_id: HashMap<[u8; 32], Channel<Signer>>,
        /// Messages to send to peers - 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>,
}

/// Events which we process internally but cannot be procsesed immediately at the generation site
/// for some reason. They are handled in timer_tick_occurred, so may be processed with
/// quite some time lag.
enum BackgroundEvent {
        /// Handle a ChannelMonitorUpdate that closes a channel, broadcasting its current latest holder
        /// commitment transaction.
        ClosingMonitorUpdate((OutPoint, ChannelMonitorUpdate)),
}

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.
        EmitEvent { event: events::Event },
}

/// State we hold per-peer. In the future we should put channels in here, but for now we only hold
/// the latest Init features we heard from the peer.
struct PeerState {
        latest_features: InitFeatures,
}

/// 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 KeysInterface for its keys manager, but this type alias chooses the
/// concrete type of the KeysManager.
///
/// (C-not exported) as Arcs don't make sense in bindings
pub type SimpleArcChannelManager<M, T, F, L> = ChannelManager<Arc<M>, Arc<T>, Arc<KeysManager>, Arc<F>, 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
/// helps with issues such as long function definitions. Note that the ChannelManager can take any
/// type that implements KeysInterface for its keys manager, but this type alias chooses the
/// concrete type of the KeysManager.
///
/// (C-not exported) as Arcs don't make sense in bindings
pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, M, T, F, L> = ChannelManager<&'a M, &'b T, &'c KeysManager, &'d F, &'e L>;

/// 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 (ie
/// called funding_transaction_generated for outbound channels).
///
/// Note that you can be a bit lazier about writing out ChannelManager than you can be with
/// ChannelMonitors. With ChannelMonitors you MUST write each monitor update out to disk before
/// returning from chain::Watch::watch_/update_channel, with ChannelManagers, 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
/// ChannelMonitors passed by reference to read(), those channels will be force-closed based on the
/// ChannelMonitor state and no funds will be lost (mod on-chain transaction fees).
///
/// Note that the deserializer is only implemented for (BlockHash, ChannelManager), which
/// tells you the last block hash which was block_connect()ed. You MUST rescan any blocks along
/// the "reorg path" (ie call block_disconnected() until you get to a common block and then call
/// block_connected() to step towards your best block) upon deserialization before using the
/// object!
///
/// 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.
///
/// 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.
//
// 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:
//
// `total_consistency_lock`
//  |
//  |__`forward_htlcs`
//  |   |
//  |   |__`pending_intercepted_htlcs`
//  |
//  |__`pending_inbound_payments`
//  |   |
//  |   |__`claimable_payments`
//  |   |
//  |   |__`pending_outbound_payments`
//  |       |
//  |       |__`channel_state`
//  |           |
//  |           |__`id_to_peer`
//  |           |
//  |           |__`short_to_chan_info`
//  |           |
//  |           |__`per_peer_state`
//  |               |
//  |               |__`outbound_scid_aliases`
//  |               |
//  |               |__`best_block`
//  |               |
//  |               |__`pending_events`
//  |                   |
//  |                   |__`pending_background_events`
//
pub struct ChannelManager<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
                                L::Target: Logger,
{
        default_configuration: UserConfig,
        genesis_hash: BlockHash,
        fee_estimator: LowerBoundedFeeEstimator<F>,
        chain_monitor: M,
        tx_broadcaster: T,

        /// 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>,

        /// See `ChannelManager` struct-level documentation for lock order requirements.
        #[cfg(any(test, feature = "_test_utils"))]
        pub(super) channel_state: Mutex<ChannelHolder<<K::Target as KeysInterface>::Signer>>,
        #[cfg(not(any(test, feature = "_test_utils")))]
        channel_state: Mutex<ChannelHolder<<K::Target as KeysInterface>::Signer>>,

        /// 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: Mutex<HashMap<PaymentId, PendingOutboundPayment>>,

        /// 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.
        ///
        /// 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<[u8; 32], 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, [u8; 32])>>,
        #[cfg(not(test))]
        short_to_chan_info: FairRwLock<HashMap<u64, (PublicKey, [u8; 32])>>,

        our_network_key: SecretKey,
        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 will eventually be here (channels and message queues and the like).
        /// 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. Sadly, this prevents parallel operation when opening a
        /// new channel.
        ///
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        per_peer_state: RwLock<HashMap<PublicKey, Mutex<PeerState>>>,

        /// See `ChannelManager` struct-level documentation for lock order requirements.
        pending_events: Mutex<Vec<events::Event>>,
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        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<()>,

        persistence_notifier: Notifier,

        keys_manager: K,

        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)]
enum NotifyOption {
        DoPersist,
        SkipPersist,
}

/// 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: Fn() -> NotifyOption> {
        persistence_notifier: &'a Notifier,
        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
        fn notify_on_drop(lock: &'a RwLock<()>, notifier: &'a Notifier) -> PersistenceNotifierGuard<'a, impl Fn() -> NotifyOption> {
                PersistenceNotifierGuard::optionally_notify(lock, notifier, || -> NotifyOption { NotifyOption::DoPersist })
        }

        fn optionally_notify<F: Fn() -> NotifyOption>(lock: &'a RwLock<()>, notifier: &'a Notifier, persist_check: F) -> PersistenceNotifierGuard<'a, F> {
                let read_guard = lock.read().unwrap();

                PersistenceNotifierGuard {
                        persistence_notifier: notifier,
                        should_persist: persist_check,
                        _read_guard: read_guard,
                }
        }
}

impl<'a, F: Fn() -> NotifyOption> Drop for PersistenceNotifierGuard<'a, F> {
        fn drop(&mut self) {
                if (self.should_persist)() == NotifyOption::DoPersist {
                        self.persistence_notifier.notify();
                }
        }
}

/// 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` 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: u32 = HTLC_FAIL_BACK_BUFFER + 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`] until we time-out the
/// idempotency of payments by [`PaymentId`]. See
/// [`ChannelManager::remove_stale_resolved_payments`].
pub(crate) const IDEMPOTENCY_TIMEOUT_TICKS: u8 = 7;

/// 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: [u8; 32],
        /// 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` passed in to create_channel, or a random value if the channel was
        /// inbound. This may be zero for inbound channels serialized with LDK versions prior to
        /// 0.0.113.
        pub user_channel_id: u128,
        /// 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::balance_msat`] and [`ChannelDetails::outbound_capacity_msat`].
        pub next_outbound_htlc_limit_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,
        /// 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)
        }
}

/// If a payment fails to send, it can be in one of several states. This enum is returned as the
/// Err() type describing which state the payment is in, see the description of individual enum
/// states for more.
#[derive(Clone, Debug)]
pub enum PaymentSendFailure {
        /// A parameter which was passed to send_payment was invalid, preventing us from attempting to
        /// send the payment at all.
        ///
        /// You can freely resend the payment in full (with the parameter error fixed).
        ///
        /// Because the payment failed outright, no payment tracking is done, you do not need to call
        /// [`ChannelManager::abandon_payment`] and [`ChannelManager::retry_payment`] will *not* work
        /// for this payment.
        ParameterError(APIError),
        /// A parameter in a single path which was passed to send_payment was invalid, preventing us
        /// from attempting to send the payment at all.
        ///
        /// You can freely resend the payment in full (with the parameter error fixed).
        ///
        /// The results here are ordered the same as the paths in the route object which was passed to
        /// send_payment.
        ///
        /// Because the payment failed outright, no payment tracking is done, you do not need to call
        /// [`ChannelManager::abandon_payment`] and [`ChannelManager::retry_payment`] will *not* work
        /// for this payment.
        PathParameterError(Vec<Result<(), APIError>>),
        /// All paths which were attempted failed to send, with no channel state change taking place.
        /// You can freely resend the payment in full (though you probably want to do so over different
        /// paths than the ones selected).
        ///
        /// Because the payment failed outright, no payment tracking is done, you do not need to call
        /// [`ChannelManager::abandon_payment`] and [`ChannelManager::retry_payment`] will *not* work
        /// for this payment.
        AllFailedResendSafe(Vec<APIError>),
        /// Indicates that a payment for the provided [`PaymentId`] is already in-flight and has not
        /// yet completed (i.e. generated an [`Event::PaymentSent`]) or been abandoned (via
        /// [`ChannelManager::abandon_payment`]).
        ///
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        DuplicatePayment,
        /// Some paths which were attempted failed to send, though possibly not all. At least some
        /// paths have irrevocably committed to the HTLC and retrying the payment in full would result
        /// in over-/re-payment.
        ///
        /// The results here are ordered the same as the paths in the route object which was passed to
        /// send_payment, and any `Err`s which are not [`APIError::MonitorUpdateInProgress`] can be
        /// safely retried via [`ChannelManager::retry_payment`].
        ///
        /// Any entries which contain `Err(APIError::MonitorUpdateInprogress)` or `Ok(())` MUST NOT be
        /// retried as they will result in over-/re-payment. These HTLCs all either successfully sent
        /// (in the case of `Ok(())`) or will send once a [`MonitorEvent::Completed`] is provided for
        /// the next-hop channel with the latest update_id.
        PartialFailure {
                /// The errors themselves, in the same order as the route hops.
                results: Vec<Result<(), APIError>>,
                /// If some paths failed without irrevocably committing to the new HTLC(s), this will
                /// contain a [`RouteParameters`] object which can be used to calculate a new route that
                /// will pay all remaining unpaid balance.
                failed_paths_retry: Option<RouteParameters>,
                /// The payment id for the payment, which is now at least partially pending.
                payment_id: PaymentId,
        },
}

/// Route hints used in constructing invoices for [phantom node payents].
///
/// [phantom node payments]: crate::chain::keysinterface::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) => {
                match $internal {
                        Ok(msg) => Ok(msg),
                        Err(MsgHandleErrInternal { err, chan_id, shutdown_finish }) => {
                                #[cfg(debug_assertions)]
                                {
                                        // In testing, ensure there are no deadlocks where the lock is already held upon
                                        // entering the macro.
                                        assert!($self.channel_state.try_lock().is_ok());
                                        assert!($self.pending_events.try_lock().is_ok());
                                }

                                let mut msg_events = Vec::with_capacity(2);

                                if let Some((shutdown_res, update_option)) = shutdown_finish {
                                        $self.finish_force_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(events::Event::ChannelClosed {
                                                        channel_id, user_channel_id,
                                                        reason: ClosureReason::ProcessingError { err: err.err.clone() }
                                                });
                                        }
                                }

                                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() {
                                        $self.channel_state.lock().unwrap().pending_msg_events.append(&mut msg_events);
                                }

                                // Return error in case higher-API need one
                                Err(err)
                        },
                }
        }
}

macro_rules! update_maps_on_chan_removal {
        ($self: expr, $channel: expr) => {{
                $self.id_to_peer.lock().unwrap().remove(&$channel.channel_id());
                let mut short_to_chan_info = $self.short_to_chan_info.write().unwrap();
                if let Some(short_id) = $channel.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.outbound_scid_alias());
                        debug_assert!(alias_removed);
                }
                short_to_chan_info.remove(&$channel.outbound_scid_alias());
        }}
}

/// Returns (boolean indicating if we should remove the Channel object from memory, a mapped error)
macro_rules! convert_chan_err {
        ($self: ident, $err: expr, $channel: expr, $channel_id: expr) => {
                match $err {
                        ChannelError::Warn(msg) => {
                                (false, MsgHandleErrInternal::from_chan_no_close(ChannelError::Warn(msg), $channel_id.clone()))
                        },
                        ChannelError::Ignore(msg) => {
                                (false, MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore(msg), $channel_id.clone()))
                        },
                        ChannelError::Close(msg) => {
                                log_error!($self.logger, "Closing channel {} due to close-required error: {}", log_bytes!($channel_id[..]), msg);
                                update_maps_on_chan_removal!($self, $channel);
                                let shutdown_res = $channel.force_shutdown(true);
                                (true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, $channel.get_user_id(),
                                        shutdown_res, $self.get_channel_update_for_broadcast(&$channel).ok()))
                        },
                }
        }
}

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

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

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

macro_rules! handle_monitor_update_res {
        ($self: ident, $err: expr, $chan: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $resend_channel_ready: expr, $failed_forwards: expr, $failed_fails: expr, $failed_finalized_fulfills: expr, $chan_id: expr) => {
                match $err {
                        ChannelMonitorUpdateStatus::PermanentFailure => {
                                log_error!($self.logger, "Closing channel {} due to monitor update ChannelMonitorUpdateStatus::PermanentFailure", log_bytes!($chan_id[..]));
                                update_maps_on_chan_removal!($self, $chan);
                                // TODO: $failed_fails is dropped here, which will cause other channels to hit the
                                // chain in a confused state! We need to move them into the ChannelMonitor which
                                // will be responsible for failing backwards once things confirm on-chain.
                                // It's ok that we drop $failed_forwards here - at this point we'd rather they
                                // broadcast HTLC-Timeout and pay the associated fees to get their funds back than
                                // us bother trying to claim it just to forward on to another peer. If we're
                                // splitting hairs we'd prefer to claim payments that were to us, but we haven't
                                // given up the preimage yet, so might as well just wait until the payment is
                                // retried, avoiding the on-chain fees.
                                let res: Result<(), _> = Err(MsgHandleErrInternal::from_finish_shutdown("ChannelMonitor storage failure".to_owned(), *$chan_id, $chan.get_user_id(),
                                                $chan.force_shutdown(false), $self.get_channel_update_for_broadcast(&$chan).ok() ));
                                (res, true)
                        },
                        ChannelMonitorUpdateStatus::InProgress => {
                                log_info!($self.logger, "Disabling channel {} due to monitor update in progress. On restore will send {} and process {} forwards, {} fails, and {} fulfill finalizations",
                                                log_bytes!($chan_id[..]),
                                                if $resend_commitment && $resend_raa {
                                                                match $action_type {
                                                                        RAACommitmentOrder::CommitmentFirst => { "commitment then RAA" },
                                                                        RAACommitmentOrder::RevokeAndACKFirst => { "RAA then commitment" },
                                                                }
                                                        } else if $resend_commitment { "commitment" }
                                                        else if $resend_raa { "RAA" }
                                                        else { "nothing" },
                                                (&$failed_forwards as &Vec<(PendingHTLCInfo, u64)>).len(),
                                                (&$failed_fails as &Vec<(HTLCSource, PaymentHash, HTLCFailReason)>).len(),
                                                (&$failed_finalized_fulfills as &Vec<HTLCSource>).len());
                                if !$resend_commitment {
                                        debug_assert!($action_type == RAACommitmentOrder::RevokeAndACKFirst || !$resend_raa);
                                }
                                if !$resend_raa {
                                        debug_assert!($action_type == RAACommitmentOrder::CommitmentFirst || !$resend_commitment);
                                }
                                $chan.monitor_updating_paused($resend_raa, $resend_commitment, $resend_channel_ready, $failed_forwards, $failed_fails, $failed_finalized_fulfills);
                                (Err(MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore("Failed to update ChannelMonitor".to_owned()), *$chan_id)), false)
                        },
                        ChannelMonitorUpdateStatus::Completed => {
                                (Ok(()), false)
                        },
                }
        };
        ($self: ident, $err: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $resend_channel_ready: expr, $failed_forwards: expr, $failed_fails: expr, $failed_finalized_fulfills: expr) => { {
                let (res, drop) = handle_monitor_update_res!($self, $err, $entry.get_mut(), $action_type, $resend_raa, $resend_commitment, $resend_channel_ready, $failed_forwards, $failed_fails, $failed_finalized_fulfills, $entry.key());
                if drop {
                        $entry.remove_entry();
                }
                res
        } };
        ($self: ident, $err: expr, $entry: expr, $action_type: path, $chan_id: expr, COMMITMENT_UPDATE_ONLY) => { {
                debug_assert!($action_type == RAACommitmentOrder::CommitmentFirst);
                handle_monitor_update_res!($self, $err, $entry, $action_type, false, true, false, Vec::new(), Vec::new(), Vec::new(), $chan_id)
        } };
        ($self: ident, $err: expr, $entry: expr, $action_type: path, $chan_id: expr, NO_UPDATE) => {
                handle_monitor_update_res!($self, $err, $entry, $action_type, false, false, false, Vec::new(), Vec::new(), Vec::new(), $chan_id)
        };
        ($self: ident, $err: expr, $entry: expr, $action_type: path, $resend_channel_ready: expr, OPTIONALLY_RESEND_FUNDING_LOCKED) => {
                handle_monitor_update_res!($self, $err, $entry, $action_type, false, false, $resend_channel_ready, Vec::new(), Vec::new(), Vec::new())
        };
        ($self: ident, $err: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
                handle_monitor_update_res!($self, $err, $entry, $action_type, $resend_raa, $resend_commitment, false, Vec::new(), Vec::new(), Vec::new())
        };
        ($self: ident, $err: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr) => {
                handle_monitor_update_res!($self, $err, $entry, $action_type, $resend_raa, $resend_commitment, false, $failed_forwards, $failed_fails, Vec::new())
        };
}

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.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.outbound_scid_alias(), ($channel.get_counterparty_node_id(), $channel.channel_id()));
                assert!(outbound_alias_insert.is_none() || outbound_alias_insert.unwrap() == ($channel.get_counterparty_node_id(), $channel.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) = $channel.get_short_channel_id() {
                        let scid_insert = short_to_chan_info.insert(real_scid, ($channel.get_counterparty_node_id(), $channel.channel_id()));
                        assert!(scid_insert.is_none() || scid_insert.unwrap() == ($channel.get_counterparty_node_id(), $channel.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_ready_event {
        ($self: expr, $channel: expr) => {
                if $channel.should_emit_channel_ready_event() {
                        {
                                let mut pending_events = $self.pending_events.lock().unwrap();
                                pending_events.push(events::Event::ChannelReady {
                                        channel_id: $channel.channel_id(),
                                        user_channel_id: $channel.get_user_id(),
                                        counterparty_node_id: $channel.get_counterparty_node_id(),
                                        channel_type: $channel.get_channel_type().clone(),
                                });
                        }
                        $channel.set_channel_ready_event_emitted();
                }
        }
}

impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F, L>
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        /// Constructs a new ChannelManager to hold several channels and route between them.
        ///
        /// 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.latest_hash`.
        pub fn new(fee_est: F, chain_monitor: M, tx_broadcaster: T, logger: L, keys_manager: K, config: UserConfig, params: ChainParameters) -> Self {
                let mut secp_ctx = Secp256k1::new();
                secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
                let inbound_pmt_key_material = keys_manager.get_inbound_payment_key_material();
                let expanded_inbound_key = inbound_payment::ExpandedKey::new(&inbound_pmt_key_material);
                ChannelManager {
                        default_configuration: config.clone(),
                        genesis_hash: genesis_block(params.network).header.block_hash(),
                        fee_estimator: LowerBoundedFeeEstimator::new(fee_est),
                        chain_monitor,
                        tx_broadcaster,

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

                        channel_state: Mutex::new(ChannelHolder{
                                by_id: HashMap::new(),
                                pending_msg_events: Vec::new(),
                        }),
                        outbound_scid_aliases: Mutex::new(HashSet::new()),
                        pending_inbound_payments: Mutex::new(HashMap::new()),
                        pending_outbound_payments: Mutex::new(HashMap::new()),
                        forward_htlcs: Mutex::new(HashMap::new()),
                        claimable_payments: Mutex::new(ClaimablePayments { claimable_htlcs: 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_key: keys_manager.get_node_secret(Recipient::Node).unwrap(),
                        our_network_pubkey: PublicKey::from_secret_key(&secp_ctx, &keys_manager.get_node_secret(Recipient::Node).unwrap()),
                        secp_ctx,

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

                        probing_cookie_secret: keys_manager.get_secure_random_bytes(),

                        highest_seen_timestamp: AtomicUsize::new(0),

                        per_peer_state: RwLock::new(HashMap::new()),

                        pending_events: Mutex::new(Vec::new()),
                        pending_background_events: Mutex::new(Vec::new()),
                        total_consistency_lock: RwLock::new(()),
                        persistence_notifier: Notifier::new(),

                        keys_manager,

                        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.genesis_hash, &self.fake_scid_rand_bytes, &self.keys_manager);
                        }
                        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`.
        ///
        /// 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).
        ///
        /// 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, override_config: Option<UserConfig>) -> Result<[u8; 32], 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 channel = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        match per_peer_state.get(&their_network_key) {
                                Some(peer_state) => {
                                        let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                                        let peer_state = peer_state.lock().unwrap();
                                        let their_features = &peer_state.latest_features;
                                        let config = if override_config.is_some() { override_config.as_ref().unwrap() } else { &self.default_configuration };
                                        match Channel::new_outbound(&self.fee_estimator, &self.keys_manager, their_network_key,
                                                their_features, channel_value_satoshis, push_msat, user_channel_id, config,
                                                self.best_block.read().unwrap().height(), outbound_scid_alias)
                                        {
                                                Ok(res) => res,
                                                Err(e) => {
                                                        self.outbound_scid_aliases.lock().unwrap().remove(&outbound_scid_alias);
                                                        return Err(e);
                                                },
                                        }
                                },
                                None => return Err(APIError::ChannelUnavailable { err: format!("Not connected to node: {}", their_network_key) }),
                        }
                };
                let res = channel.get_open_channel(self.genesis_hash.clone());

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

                let temporary_channel_id = channel.channel_id();
                let mut channel_state = self.channel_state.lock().unwrap();
                match channel_state.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(channel); }
                }
                channel_state.pending_msg_events.push(events::MessageSendEvent::SendOpenChannel {
                        node_id: their_network_key,
                        msg: res,
                });
                Ok(temporary_channel_id)
        }

        fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<<K::Target as KeysInterface>::Signer>)) -> bool>(&self, f: Fn) -> Vec<ChannelDetails> {
                let mut res = Vec::new();
                {
                        let channel_state = self.channel_state.lock().unwrap();
                        let best_block_height = self.best_block.read().unwrap().height();
                        res.reserve(channel_state.by_id.len());
                        for (channel_id, channel) in channel_state.by_id.iter().filter(f) {
                                let balance = channel.get_available_balances();
                                let (to_remote_reserve_satoshis, to_self_reserve_satoshis) =
                                        channel.get_holder_counterparty_selected_channel_reserve_satoshis();
                                res.push(ChannelDetails {
                                        channel_id: (*channel_id).clone(),
                                        counterparty: ChannelCounterparty {
                                                node_id: channel.get_counterparty_node_id(),
                                                features: InitFeatures::empty(),
                                                unspendable_punishment_reserve: to_remote_reserve_satoshis,
                                                forwarding_info: channel.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 channel.have_received_message() {
                                                        Some(channel.get_counterparty_htlc_minimum_msat()) } else { None },
                                                outbound_htlc_maximum_msat: channel.get_counterparty_htlc_maximum_msat(),
                                        },
                                        funding_txo: channel.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 channel.have_received_message() { Some(channel.get_channel_type().clone()) } else { None },
                                        short_channel_id: channel.get_short_channel_id(),
                                        outbound_scid_alias: if channel.is_usable() { Some(channel.outbound_scid_alias()) } else { None },
                                        inbound_scid_alias: channel.latest_inbound_scid_alias(),
                                        channel_value_satoshis: channel.get_value_satoshis(),
                                        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,
                                        user_channel_id: channel.get_user_id(),
                                        confirmations_required: channel.minimum_depth(),
                                        confirmations: Some(channel.get_funding_tx_confirmations(best_block_height)),
                                        force_close_spend_delay: channel.get_counterparty_selected_contest_delay(),
                                        is_outbound: channel.is_outbound(),
                                        is_channel_ready: channel.is_usable(),
                                        is_usable: channel.is_live(),
                                        is_public: channel.should_announce(),
                                        inbound_htlc_minimum_msat: Some(channel.get_holder_htlc_minimum_msat()),
                                        inbound_htlc_maximum_msat: channel.get_holder_htlc_maximum_msat(),
                                        config: Some(channel.config()),
                                });
                        }
                }
                let per_peer_state = self.per_peer_state.read().unwrap();
                for chan in res.iter_mut() {
                        if let Some(peer_state) = per_peer_state.get(&chan.counterparty.node_id) {
                                chan.counterparty.features = peer_state.lock().unwrap().latest_features.clone();
                        }
                }
                res
        }

        /// Gets the list of open channels, in random order. See ChannelDetail field documentation for
        /// more information.
        pub fn list_channels(&self) -> Vec<ChannelDetails> {
                self.list_channels_with_filter(|_| true)
        }

        /// Gets the list of usable channels, in random order. Useful as an argument to [`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.
        ///
        /// [`find_route`]: crate::routing::router::find_route
        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_channels_with_filter(|&(_, ref channel)| channel.is_live())
        }

        /// Helper function that issues the channel close events
        fn issue_channel_close_events(&self, channel: &Channel<<K::Target as KeysInterface>::Signer>, closure_reason: ClosureReason) {
                let mut pending_events_lock = self.pending_events.lock().unwrap();
                match channel.unbroadcasted_funding() {
                        Some(transaction) => {
                                pending_events_lock.push(events::Event::DiscardFunding { channel_id: channel.channel_id(), transaction })
                        },
                        None => {},
                }
                pending_events_lock.push(events::Event::ChannelClosed {
                        channel_id: channel.channel_id(),
                        user_channel_id: channel.get_user_id(),
                        reason: closure_reason
                });
        }

        fn close_channel_internal(&self, channel_id: &[u8; 32], counterparty_node_id: &PublicKey, target_feerate_sats_per_1000_weight: Option<u32>) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                let mut failed_htlcs: Vec<(HTLCSource, PaymentHash)>;
                let result: Result<(), _> = loop {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        match channel_state.by_id.entry(channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_entry) => {
                                        if *counterparty_node_id != chan_entry.get().get_counterparty_node_id(){
                                                return Err(APIError::APIMisuseError { err: "The passed counterparty_node_id doesn't match the channel's counterparty node_id".to_owned() });
                                        }
                                        let (shutdown_msg, monitor_update, htlcs) = {
                                                let per_peer_state = self.per_peer_state.read().unwrap();
                                                match per_peer_state.get(&counterparty_node_id) {
                                                        Some(peer_state) => {
                                                                let peer_state = peer_state.lock().unwrap();
                                                                let their_features = &peer_state.latest_features;
                                                                chan_entry.get_mut().get_shutdown(&self.keys_manager, their_features, target_feerate_sats_per_1000_weight)?
                                                        },
                                                        None => return Err(APIError::ChannelUnavailable { err: format!("Not connected to node: {}", counterparty_node_id) }),
                                                }
                                        };
                                        failed_htlcs = htlcs;

                                        // Update the monitor with the shutdown script if necessary.
                                        if let Some(monitor_update) = monitor_update {
                                                let update_res = self.chain_monitor.update_channel(chan_entry.get().get_funding_txo().unwrap(), monitor_update);
                                                let (result, is_permanent) =
                                                        handle_monitor_update_res!(self, update_res, chan_entry.get_mut(), RAACommitmentOrder::CommitmentFirst, chan_entry.key(), NO_UPDATE);
                                                if is_permanent {
                                                        remove_channel!(self, chan_entry);
                                                        break result;
                                                }
                                        }

                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                node_id: *counterparty_node_id,
                                                msg: shutdown_msg
                                        });

                                        if chan_entry.get().is_shutdown() {
                                                let channel = remove_channel!(self, chan_entry);
                                                if let Ok(channel_update) = self.get_channel_update_for_broadcast(&channel) {
                                                        channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                msg: channel_update
                                                        });
                                                }
                                                self.issue_channel_close_events(&channel, ClosureReason::HolderForceClosed);
                                        }
                                        break Ok(());
                                },
                                hash_map::Entry::Vacant(_) => return Err(APIError::ChannelUnavailable{err: "No such channel".to_owned()})
                        }
                };

                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);
                }

                let _ = handle_error!(self, result, *counterparty_node_id);
                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 [`Background`] and
        ///    [`ChannelConfig::force_close_avoidance_max_fee_satoshis`] plus our [`Normal`] fee
        ///    estimate.
        ///  * If our counterparty is the channel initiator, we will require a channel closing
        ///    transaction feerate of at least our [`Background`] 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.
        ///
        /// [`ChannelConfig::force_close_avoidance_max_fee_satoshis`]: crate::util::config::ChannelConfig::force_close_avoidance_max_fee_satoshis
        /// [`Background`]: crate::chain::chaininterface::ConfirmationTarget::Background
        /// [`Normal`]: crate::chain::chaininterface::ConfirmationTarget::Normal
        pub fn close_channel(&self, channel_id: &[u8; 32], counterparty_node_id: &PublicKey) -> Result<(), APIError> {
                self.close_channel_internal(channel_id, counterparty_node_id, 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 [`Normal`] 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).
        ///
        /// May generate a SendShutdown message event on success, which should be relayed.
        ///
        /// [`ChannelConfig::force_close_avoidance_max_fee_satoshis`]: crate::util::config::ChannelConfig::force_close_avoidance_max_fee_satoshis
        /// [`Background`]: crate::chain::chaininterface::ConfirmationTarget::Background
        /// [`Normal`]: crate::chain::chaininterface::ConfirmationTarget::Normal
        pub fn close_channel_with_target_feerate(&self, channel_id: &[u8; 32], counterparty_node_id: &PublicKey, target_feerate_sats_per_1000_weight: u32) -> Result<(), APIError> {
                self.close_channel_internal(channel_id, counterparty_node_id, Some(target_feerate_sats_per_1000_weight))
        }

        #[inline]
        fn finish_force_close_channel(&self, shutdown_res: ShutdownResult) {
                let (monitor_update_option, mut failed_htlcs) = shutdown_res;
                log_debug!(self.logger, "Finishing force-closure of channel with {} HTLCs to fail", failed_htlcs.len());
                for htlc_source in failed_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)) = monitor_update_option {
                        // 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);
                }
        }

        /// `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: &[u8; 32], peer_node_id: &PublicKey, peer_msg: Option<&String>, broadcast: bool)
        -> Result<PublicKey, APIError> {
                let mut chan = {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        if let hash_map::Entry::Occupied(chan) = channel_state.by_id.entry(channel_id.clone()) {
                                if chan.get().get_counterparty_node_id() != *peer_node_id {
                                        return Err(APIError::ChannelUnavailable{err: "No such channel".to_owned()});
                                }
                                if let Some(peer_msg) = peer_msg {
                                        self.issue_channel_close_events(chan.get(),ClosureReason::CounterpartyForceClosed { peer_msg: peer_msg.to_string() });
                                } else {
                                        self.issue_channel_close_events(chan.get(),ClosureReason::HolderForceClosed);
                                }
                                remove_channel!(self, chan)
                        } else {
                                return Err(APIError::ChannelUnavailable{err: "No such channel".to_owned()});
                        }
                };
                log_error!(self.logger, "Force-closing channel {}", log_bytes!(channel_id[..]));
                self.finish_force_close_channel(chan.force_shutdown(broadcast));
                if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                        let mut channel_state = self.channel_state.lock().unwrap();
                        channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                msg: update
                        });
                }

                Ok(chan.get_counterparty_node_id())
        }

        fn force_close_sending_error(&self, channel_id: &[u8; 32], counterparty_node_id: &PublicKey, broadcast: bool) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                match self.force_close_channel_with_peer(channel_id, counterparty_node_id, None, broadcast) {
                        Ok(counterparty_node_id) => {
                                self.channel_state.lock().unwrap().pending_msg_events.push(
                                        events::MessageSendEvent::HandleError {
                                                node_id: counterparty_node_id,
                                                action: msgs::ErrorAction::SendErrorMessage {
                                                        msg: 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: &[u8; 32], 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: &[u8; 32], 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 construct_recv_pending_htlc_info(&self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32],
                payment_hash: PaymentHash, amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>) -> Result<PendingHTLCInfo, ReceiveError>
        {
                // final_incorrect_cltv_expiry
                if hop_data.outgoing_cltv_value != cltv_expiry {
                        return Err(ReceiveError {
                                msg: "Upstream node set CLTV to the wrong value",
                                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).
                let current_height: u32 = self.best_block.read().unwrap().height();
                if (hop_data.outgoing_cltv_value as u64) <= current_height as u64 + HTLC_FAIL_BACK_BUFFER as u64 + 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(ReceiveError {
                                err_code: 0x4000 | 15, err_data,
                                msg: "The final CLTV expiry is too soon to handle",
                        });
                }
                if hop_data.amt_to_forward > amt_msat {
                        return Err(ReceiveError {
                                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 = match hop_data.format {
                        msgs::OnionHopDataFormat::NonFinalNode { .. } => {
                                return Err(ReceiveError {
                                        err_code: 0x4000|22,
                                        err_data: Vec::new(),
                                        msg: "Got non final data with an HMAC of 0",
                                });
                        },
                        msgs::OnionHopDataFormat::FinalNode { payment_data, keysend_preimage } => {
                                if payment_data.is_some() && keysend_preimage.is_some() {
                                        return Err(ReceiveError {
                                                err_code: 0x4000|22,
                                                err_data: Vec::new(),
                                                msg: "We don't support MPP keysend payments",
                                        });
                                } else if let Some(data) = payment_data {
                                        PendingHTLCRouting::Receive {
                                                payment_data: data,
                                                incoming_cltv_expiry: hop_data.outgoing_cltv_value,
                                                phantom_shared_secret,
                                        }
                                } else 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).into_inner());
                                        if hashed_preimage != payment_hash {
                                                return Err(ReceiveError {
                                                        err_code: 0x4000|22,
                                                        err_data: Vec::new(),
                                                        msg: "Payment preimage didn't match payment hash",
                                                });
                                        }

                                        PendingHTLCRouting::ReceiveKeysend {
                                                payment_preimage,
                                                incoming_cltv_expiry: hop_data.outgoing_cltv_value,
                                        }
                                } else {
                                        return Err(ReceiveError {
                                                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: amt_msat,
                        outgoing_cltv_value: hop_data.outgoing_cltv_value,
                })
        }

        fn decode_update_add_htlc_onion(&self, msg: &msgs::UpdateAddHTLC) -> PendingHTLCStatus {
                macro_rules! return_malformed_err {
                        ($msg: expr, $err_code: expr) => {
                                {
                                        log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                        return PendingHTLCStatus::Fail(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).into_inner(),
                                                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 = SharedSecret::new(&msg.onion_routing_packet.public_key.unwrap(), &self.our_network_key).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!(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),
                                        }));
                                }
                        }
                }

                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) {
                        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 pending_forward_info = match next_hop {
                        onion_utils::Hop::Receive(next_hop_data) => {
                                // OUR PAYMENT!
                                match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry, None) {
                                        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(ReceiveError { 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 } => {
                                let new_pubkey = msg.onion_routing_packet.public_key.unwrap();
                                let outgoing_packet = msgs::OnionPacket {
                                        version: 0,
                                        public_key: onion_utils::next_hop_packet_pubkey(&self.secp_ctx, new_pubkey, &shared_secret),
                                        hop_data: new_packet_bytes,
                                        hmac: next_hop_hmac.clone(),
                                };

                                let short_channel_id = match next_hop_data.format {
                                        msgs::OnionHopDataFormat::NonFinalNode { short_channel_id } => short_channel_id,
                                        msgs::OnionHopDataFormat::FinalNode { .. } => {
                                                return_err!("Final Node OnionHopData provided for us as an intermediary node", 0x4000 | 22, &[0;0]);
                                        },
                                };

                                PendingHTLCStatus::Forward(PendingHTLCInfo {
                                        routing: PendingHTLCRouting::Forward {
                                                onion_packet: outgoing_packet,
                                                short_channel_id,
                                        },
                                        payment_hash: msg.payment_hash.clone(),
                                        incoming_shared_secret: shared_secret,
                                        incoming_amt_msat: Some(msg.amount_msat),
                                        outgoing_amt_msat: next_hop_data.amt_to_forward,
                                        outgoing_cltv_value: next_hop_data.outgoing_cltv_value,
                                })
                        }
                };

                if let &PendingHTLCStatus::Forward(PendingHTLCInfo { ref routing, ref outgoing_amt_msat, ref outgoing_cltv_value, .. }) = &pending_forward_info {
                        // If short_channel_id is 0 here, we'll reject the HTLC as there cannot be a channel
                        // with a short_channel_id of 0. This is important as various things later assume
                        // short_channel_id is non-0 in any ::Forward.
                        if let &PendingHTLCRouting::Forward { ref short_channel_id, .. } = routing {
                                if let Some((err, mut code, chan_update)) = loop {
                                        let id_option = self.short_to_chan_info.read().unwrap().get(&short_channel_id).cloned();
                                        let mut channel_state = self.channel_state.lock().unwrap();
                                        let forwarding_id_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, *short_channel_id, &self.genesis_hash)) ||
                                                           fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash)
                                                        {
                                                                None
                                                        } else {
                                                                break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
                                                        }
                                                },
                                                Some((_cp_id, chan_id)) => Some(chan_id.clone()),
                                        };
                                        let chan_update_opt = if let Some(forwarding_id) = forwarding_id_opt {
                                                let chan = match channel_state.by_id.get_mut(&forwarding_id) {
                                                        None => {
                                                                // Channel was removed. The short_to_chan_info and 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.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.get_channel_type().supports_scid_privacy() && *short_channel_id != chan.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(*short_channel_id, 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.is_live() { // channel_disabled
                                                        break Some(("Forwarding channel is not in a ready state.", 0x1000 | 20, chan_update_opt));
                                                }
                                                if *outgoing_amt_msat < chan.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 {
                                                if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + MIN_CLTV_EXPIRY_DELTA as u64 {
                                                        // 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((
                                                                "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
                                                                0x2000 | 2, None,
                                                        ));
                                                }
                                                None
                                        };

                                        let cur_height = self.best_block.read().unwrap().height() + 1;
                                        // 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 msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon
                                                break Some(("CLTV expiry is too close", 0x1000 | 14, chan_update_opt));
                                        }
                                        if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far
                                                break Some(("CLTV expiry is too far in the future", 21, None));
                                        }
                                        // 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 {
                                                break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, 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[..]);
                                }
                        }
                }

                pending_forward_info
        }

        /// 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.
        ///
        /// May be called with channel_state already locked!
        fn get_channel_update_for_broadcast(&self, chan: &Channel<<K::Target as KeysInterface>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                if !chan.should_announce() {
                        return Err(LightningError {
                                err: "Cannot broadcast a channel_update for a private channel".to_owned(),
                                action: msgs::ErrorAction::IgnoreError
                        });
                }
                if chan.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 {}", log_bytes!(chan.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 short_id),
        /// 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.
        /// May be called with channel_state already locked!
        fn get_channel_update_for_unicast(&self, chan: &Channel<<K::Target as KeysInterface>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                log_trace!(self.logger, "Attempting to generate channel update for channel {}", log_bytes!(chan.channel_id()));
                let short_channel_id = match chan.get_short_channel_id().or(chan.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<<K::Target as KeysInterface>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                log_trace!(self.logger, "Generating channel update for channel {}", log_bytes!(chan.channel_id()));
                let were_node_one = PublicKey::from_secret_key(&self.secp_ctx, &self.our_network_key).serialize()[..] < chan.get_counterparty_node_id().serialize()[..];

                let unsigned = msgs::UnsignedChannelUpdate {
                        chain_hash: self.genesis_hash,
                        short_channel_id,
                        timestamp: chan.get_update_time_counter(),
                        flags: (!were_node_one) as u8 | ((!chan.is_live() as u8) << 1),
                        cltv_expiry_delta: chan.get_cltv_expiry_delta(),
                        htlc_minimum_msat: chan.get_counterparty_htlc_minimum_msat(),
                        htlc_maximum_msat: chan.get_announced_htlc_max_msat(),
                        fee_base_msat: chan.get_outbound_forwarding_fee_base_msat(),
                        fee_proportional_millionths: chan.get_fee_proportional_millionths(),
                        excess_data: Vec::new(),
                };

                let msg_hash = Sha256dHash::hash(&unsigned.encode()[..]);
                let sig = self.secp_ctx.sign_ecdsa(&hash_to_message!(&msg_hash[..]), &self.our_network_key);

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

        // Only public for testing, this should otherwise never be called direcly
        pub(crate) fn send_payment_along_path(&self, path: &Vec<RouteHop>, payment_params: &Option<PaymentParameters>, payment_hash: &PaymentHash, payment_secret: &Option<PaymentSecret>, total_value: u64, cur_height: u32, payment_id: PaymentId, keysend_preimage: &Option<PaymentPreimage>, session_priv_bytes: [u8; 32]) -> Result<(), APIError> {
                log_trace!(self.logger, "Attempting to send payment for path with next hop {}", path.first().unwrap().short_channel_id);
                let prng_seed = self.keys_manager.get_secure_random_bytes();
                let session_priv = SecretKey::from_slice(&session_priv_bytes[..]).expect("RNG is busted");

                let onion_keys = onion_utils::construct_onion_keys(&self.secp_ctx, &path, &session_priv)
                        .map_err(|_| APIError::InvalidRoute{err: "Pubkey along hop was maliciously selected"})?;
                let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(path, total_value, payment_secret, cur_height, keysend_preimage)?;
                if onion_utils::route_size_insane(&onion_payloads) {
                        return Err(APIError::InvalidRoute{err: "Route size too large considering onion data"});
                }
                let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, prng_seed, payment_hash);

                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

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

                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        if let hash_map::Entry::Occupied(mut chan) = channel_state.by_id.entry(id) {
                                match {
                                        if chan.get().get_counterparty_node_id() != path.first().unwrap().pubkey {
                                                return Err(APIError::InvalidRoute{err: "Node ID mismatch on first hop!"});
                                        }
                                        if !chan.get().is_live() {
                                                return Err(APIError::ChannelUnavailable{err: "Peer for first hop currently disconnected/pending monitor update!".to_owned()});
                                        }
                                        break_chan_entry!(self, chan.get_mut().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,
                                                        payment_secret: payment_secret.clone(),
                                                        payment_params: payment_params.clone(),
                                                }, onion_packet, &self.logger),
                                                chan)
                                } {
                                        Some((update_add, commitment_signed, monitor_update)) => {
                                                let update_err = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update);
                                                let chan_id = chan.get().channel_id();
                                                match (update_err,
                                                        handle_monitor_update_res!(self, update_err, chan,
                                                                RAACommitmentOrder::CommitmentFirst, false, true))
                                                {
                                                        (ChannelMonitorUpdateStatus::PermanentFailure, Err(e)) => break Err(e),
                                                        (ChannelMonitorUpdateStatus::Completed, Ok(())) => {},
                                                        (ChannelMonitorUpdateStatus::InProgress, Err(_)) => {
                                                                // 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);
                                                        },
                                                        _ => unreachable!(),
                                                }

                                                log_debug!(self.logger, "Sending payment along path resulted in a commitment_signed for channel {}", log_bytes!(chan_id));
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                        node_id: path.first().unwrap().pubkey,
                                                        updates: msgs::CommitmentUpdate {
                                                                update_add_htlcs: vec![update_add],
                                                                update_fulfill_htlcs: Vec::new(),
                                                                update_fail_htlcs: Vec::new(),
                                                                update_fail_malformed_htlcs: Vec::new(),
                                                                update_fee: None,
                                                                commitment_signed,
                                                        },
                                                });
                                        },
                                        None => { },
                                }
                        } else {
                                // The channel was likely removed after we fetched the id from the
                                // `short_to_chan_info` map, but before we successfully locked the `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.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.
        ///
        /// 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`]) 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.
        ///
        /// May generate SendHTLCs message(s) event on success, which should be relayed (e.g. via
        /// [`PeerManager::process_events`]).
        ///
        /// Each path may have a different return value, and PaymentSendValue 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 for updates
        ///    (including due to previous monitor update failure or new permanent monitor update
        ///    failure).
        ///  * [`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!
        ///
        /// payment_secret is unrelated to payment_hash (or PaymentPreimage) and exists to authenticate
        /// the sender to the recipient and prevent payment-probing (deanonymization) attacks. For
        /// newer nodes, it will be provided to you in the invoice. If you do not have one, the Route
        /// must not contain multiple paths as multi-path payments require a recipient-provided
        /// payment_secret.
        ///
        /// If a payment_secret *is* provided, we assume that the invoice had the payment_secret feature
        /// bit set (either as required or as available). If multiple paths are present in the Route,
        /// we assume the invoice had the basic_mpp feature set.
        ///
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        /// [`PeerManager::process_events`]: crate::ln::peer_handler::PeerManager::process_events
        pub fn send_payment(&self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
                let onion_session_privs = self.add_new_pending_payment(payment_hash, *payment_secret, payment_id, route)?;
                self.send_payment_internal(route, payment_hash, payment_secret, None, payment_id, None, onion_session_privs)
        }

        #[cfg(test)]
        pub(crate) fn test_add_new_pending_payment(&self, payment_hash: PaymentHash, payment_secret: Option<PaymentSecret>, payment_id: PaymentId, route: &Route) -> Result<Vec<[u8; 32]>, PaymentSendFailure> {
                self.add_new_pending_payment(payment_hash, payment_secret, payment_id, route)
        }

        fn add_new_pending_payment(&self, payment_hash: PaymentHash, payment_secret: Option<PaymentSecret>, payment_id: PaymentId, route: &Route) -> Result<Vec<[u8; 32]>, PaymentSendFailure> {
                let mut onion_session_privs = Vec::with_capacity(route.paths.len());
                for _ in 0..route.paths.len() {
                        onion_session_privs.push(self.keys_manager.get_secure_random_bytes());
                }

                let mut pending_outbounds = self.pending_outbound_payments.lock().unwrap();
                match pending_outbounds.entry(payment_id) {
                        hash_map::Entry::Occupied(_) => Err(PaymentSendFailure::DuplicatePayment),
                        hash_map::Entry::Vacant(entry) => {
                                let payment = entry.insert(PendingOutboundPayment::Retryable {
                                        session_privs: HashSet::new(),
                                        pending_amt_msat: 0,
                                        pending_fee_msat: Some(0),
                                        payment_hash,
                                        payment_secret,
                                        starting_block_height: self.best_block.read().unwrap().height(),
                                        total_msat: route.get_total_amount(),
                                });

                                for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.iter()) {
                                        assert!(payment.insert(*session_priv_bytes, path));
                                }

                                Ok(onion_session_privs)
                        },
                }
        }

        fn send_payment_internal(&self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, keysend_preimage: Option<PaymentPreimage>, payment_id: PaymentId, recv_value_msat: Option<u64>, onion_session_privs: Vec<[u8; 32]>) -> Result<(), PaymentSendFailure> {
                if route.paths.len() < 1 {
                        return Err(PaymentSendFailure::ParameterError(APIError::InvalidRoute{err: "There must be at least one path to send over"}));
                }
                if payment_secret.is_none() && route.paths.len() > 1 {
                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError{err: "Payment secret is required for multi-path payments".to_string()}));
                }
                let mut total_value = 0;
                let our_node_id = self.get_our_node_id();
                let mut path_errs = Vec::with_capacity(route.paths.len());
                'path_check: for path in route.paths.iter() {
                        if path.len() < 1 || path.len() > 20 {
                                path_errs.push(Err(APIError::InvalidRoute{err: "Path didn't go anywhere/had bogus size"}));
                                continue 'path_check;
                        }
                        for (idx, hop) in path.iter().enumerate() {
                                if idx != path.len() - 1 && hop.pubkey == our_node_id {
                                        path_errs.push(Err(APIError::InvalidRoute{err: "Path went through us but wasn't a simple rebalance loop to us"}));
                                        continue 'path_check;
                                }
                        }
                        total_value += path.last().unwrap().fee_msat;
                        path_errs.push(Ok(()));
                }
                if path_errs.iter().any(|e| e.is_err()) {
                        return Err(PaymentSendFailure::PathParameterError(path_errs));
                }
                if let Some(amt_msat) = recv_value_msat {
                        debug_assert!(amt_msat >= total_value);
                        total_value = amt_msat;
                }

                let cur_height = self.best_block.read().unwrap().height() + 1;
                let mut results = Vec::new();
                debug_assert_eq!(route.paths.len(), onion_session_privs.len());
                for (path, session_priv) in route.paths.iter().zip(onion_session_privs.into_iter()) {
                        let mut path_res = self.send_payment_along_path(&path, &route.payment_params, &payment_hash, payment_secret, total_value, cur_height, payment_id, &keysend_preimage, session_priv);
                        match path_res {
                                Ok(_) => {},
                                Err(APIError::MonitorUpdateInProgress) => {
                                        // While a MonitorUpdateInProgress is an Err(_), the payment is still
                                        // considered "in flight" and we shouldn't remove it from the
                                        // PendingOutboundPayment set.
                                },
                                Err(_) => {
                                        let mut pending_outbounds = self.pending_outbound_payments.lock().unwrap();
                                        if let Some(payment) = pending_outbounds.get_mut(&payment_id) {
                                                let removed = payment.remove(&session_priv, Some(path));
                                                debug_assert!(removed, "This can't happen as the payment has an entry for this path added by callers");
                                        } else {
                                                debug_assert!(false, "This can't happen as the payment was added by callers");
                                                path_res = Err(APIError::APIMisuseError { err: "Internal error: payment disappeared during processing. Please report this bug!".to_owned() });
                                        }
                                }
                        }
                        results.push(path_res);
                }
                let mut has_ok = false;
                let mut has_err = false;
                let mut pending_amt_unsent = 0;
                let mut max_unsent_cltv_delta = 0;
                for (res, path) in results.iter().zip(route.paths.iter()) {
                        if res.is_ok() { has_ok = true; }
                        if res.is_err() { has_err = true; }
                        if let &Err(APIError::MonitorUpdateInProgress) = res {
                                // MonitorUpdateInProgress is inherently unsafe to retry, so we call it a
                                // PartialFailure.
                                has_err = true;
                                has_ok = true;
                        } else if res.is_err() {
                                pending_amt_unsent += path.last().unwrap().fee_msat;
                                max_unsent_cltv_delta = cmp::max(max_unsent_cltv_delta, path.last().unwrap().cltv_expiry_delta);
                        }
                }
                if has_err && has_ok {
                        Err(PaymentSendFailure::PartialFailure {
                                results,
                                payment_id,
                                failed_paths_retry: if pending_amt_unsent != 0 {
                                        if let Some(payment_params) = &route.payment_params {
                                                Some(RouteParameters {
                                                        payment_params: payment_params.clone(),
                                                        final_value_msat: pending_amt_unsent,
                                                        final_cltv_expiry_delta: max_unsent_cltv_delta,
                                                })
                                        } else { None }
                                } else { None },
                        })
                } else if has_err {
                        // If we failed to send any paths, we should remove the new PaymentId from the
                        // `pending_outbound_payments` map, as the user isn't expected to `abandon_payment`.
                        let removed = self.pending_outbound_payments.lock().unwrap().remove(&payment_id).is_some();
                        debug_assert!(removed, "We should always have a pending payment to remove here");
                        Err(PaymentSendFailure::AllFailedResendSafe(results.drain(..).map(|r| r.unwrap_err()).collect()))
                } else {
                        Ok(())
                }
        }

        /// Retries a payment along the given [`Route`].
        ///
        /// Errors returned are a superset of those returned from [`send_payment`], so see
        /// [`send_payment`] documentation for more details on errors. This method will also error if the
        /// retry amount puts the payment more than 10% over the payment's total amount, if the payment
        /// for the given `payment_id` cannot be found (likely due to timeout or success), or if
        /// further retries have been disabled with [`abandon_payment`].
        ///
        /// [`send_payment`]: [`ChannelManager::send_payment`]
        /// [`abandon_payment`]: [`ChannelManager::abandon_payment`]
        pub fn retry_payment(&self, route: &Route, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
                const RETRY_OVERFLOW_PERCENTAGE: u64 = 10;
                for path in route.paths.iter() {
                        if path.len() == 0 {
                                return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                        err: "length-0 path in route".to_string()
                                }))
                        }
                }

                let mut onion_session_privs = Vec::with_capacity(route.paths.len());
                for _ in 0..route.paths.len() {
                        onion_session_privs.push(self.keys_manager.get_secure_random_bytes());
                }

                let (total_msat, payment_hash, payment_secret) = {
                        let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                        match outbounds.get_mut(&payment_id) {
                                Some(payment) => {
                                        let res = match payment {
                                                PendingOutboundPayment::Retryable {
                                                        total_msat, payment_hash, payment_secret, pending_amt_msat, ..
                                                } => {
                                                        let retry_amt_msat: u64 = route.paths.iter().map(|path| path.last().unwrap().fee_msat).sum();
                                                        if retry_amt_msat + *pending_amt_msat > *total_msat * (100 + RETRY_OVERFLOW_PERCENTAGE) / 100 {
                                                                return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                                                        err: format!("retry_amt_msat of {} will put pending_amt_msat (currently: {}) more than 10% over total_payment_amt_msat of {}", retry_amt_msat, pending_amt_msat, total_msat).to_string()
                                                                }))
                                                        }
                                                        (*total_msat, *payment_hash, *payment_secret)
                                                },
                                                PendingOutboundPayment::Legacy { .. } => {
                                                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                                                err: "Unable to retry payments that were initially sent on LDK versions prior to 0.0.102".to_string()
                                                        }))
                                                },
                                                PendingOutboundPayment::Fulfilled { .. } => {
                                                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                                                err: "Payment already completed".to_owned()
                                                        }));
                                                },
                                                PendingOutboundPayment::Abandoned { .. } => {
                                                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                                                err: "Payment already abandoned (with some HTLCs still pending)".to_owned()
                                                        }));
                                                },
                                        };
                                        for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.iter()) {
                                                assert!(payment.insert(*session_priv_bytes, path));
                                        }
                                        res
                                },
                                None =>
                                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                                err: format!("Payment with ID {} not found", log_bytes!(payment_id.0)),
                                        })),
                        }
                };
                self.send_payment_internal(route, payment_hash, &payment_secret, None, payment_id, Some(total_msat), onion_session_privs)
        }

        /// Signals that no further retries for the given payment will occur.
        ///
        /// After this method returns, no future calls to [`retry_payment`] for the given `payment_id`
        /// are allowed. 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.
        ///
        /// If an [`Event::PaymentFailed`] event is generated and we restart without this
        /// [`ChannelManager`] having been persisted, the payment may still be in the pending state
        /// upon restart. This allows further calls to [`retry_payment`] (and requiring a second call
        /// to [`abandon_payment`] to mark the payment as failed again). Otherwise, future calls to
        /// [`retry_payment`] will fail with [`PaymentSendFailure::ParameterError`].
        ///
        /// [`abandon_payment`]: Self::abandon_payment
        /// [`retry_payment`]: Self::retry_payment
        /// [`Event::PaymentFailed`]: events::Event::PaymentFailed
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        pub fn abandon_payment(&self, payment_id: PaymentId) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(payment_id) {
                        if let Ok(()) = payment.get_mut().mark_abandoned() {
                                if payment.get().remaining_parts() == 0 {
                                        self.pending_events.lock().unwrap().push(events::Event::PaymentFailed {
                                                payment_id,
                                                payment_hash: payment.get().payment_hash().expect("PendingOutboundPayments::RetriesExceeded always has a payment hash set"),
                                        });
                                        payment.remove();
                                }
                        }
                }
        }

        /// 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.
        ///
        /// Note that `route` must have exactly one path.
        ///
        /// [`send_payment`]: Self::send_payment
        pub fn send_spontaneous_payment(&self, route: &Route, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId) -> Result<PaymentHash, PaymentSendFailure> {
                let preimage = match payment_preimage {
                        Some(p) => p,
                        None => PaymentPreimage(self.keys_manager.get_secure_random_bytes()),
                };
                let payment_hash = PaymentHash(Sha256::hash(&preimage.0).into_inner());
                let onion_session_privs = self.add_new_pending_payment(payment_hash, None, payment_id, &route)?;

                match self.send_payment_internal(route, payment_hash, &None, Some(preimage), payment_id, None, onion_session_privs) {
                        Ok(()) => Ok(payment_hash),
                        Err(e) => Err(e)
                }
        }

        /// 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, hops: Vec<RouteHop>) -> Result<(PaymentHash, PaymentId), PaymentSendFailure> {
                let payment_id = PaymentId(self.keys_manager.get_secure_random_bytes());

                let payment_hash = self.probing_cookie_from_id(&payment_id);

                if hops.len() < 2 {
                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                err: "No need probing a path with less than two hops".to_string()
                        }))
                }

                let route = Route { paths: vec![hops], payment_params: None };
                let onion_session_privs = self.add_new_pending_payment(payment_hash, None, payment_id, &route)?;

                match self.send_payment_internal(&route, payment_hash, &None, None, payment_id, None, onion_session_privs) {
                        Ok(()) => Ok((payment_hash, payment_id)),
                        Err(e) => Err(e)
                }
        }

        /// Returns whether a payment with the given [`PaymentHash`] and [`PaymentId`] is, in fact, a
        /// payment probe.
        pub(crate) fn payment_is_probe(&self, payment_hash: &PaymentHash, payment_id: &PaymentId) -> bool {
                let target_payment_hash = self.probing_cookie_from_id(payment_id);
                target_payment_hash == *payment_hash
        }

        /// Returns the 'probing cookie' for the given [`PaymentId`].
        fn probing_cookie_from_id(&self, payment_id: &PaymentId) -> PaymentHash {
                let mut preimage = [0u8; 64];
                preimage[..32].copy_from_slice(&self.probing_cookie_secret);
                preimage[32..].copy_from_slice(&payment_id.0);
                PaymentHash(Sha256::hash(&preimage).into_inner())
        }

        /// 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: Fn(&Channel<<K::Target as KeysInterface>::Signer>, &Transaction) -> Result<OutPoint, APIError>>(
                &self, temporary_channel_id: &[u8; 32], _counterparty_node_id: &PublicKey, funding_transaction: Transaction, find_funding_output: FundingOutput
        ) -> Result<(), APIError> {
                let (chan, msg) = {
                        let (res, chan) = match self.channel_state.lock().unwrap().by_id.remove(temporary_channel_id) {
                                Some(mut chan) => {
                                        let funding_txo = find_funding_output(&chan, &funding_transaction)?;

                                        (chan.get_outbound_funding_created(funding_transaction, funding_txo, &self.logger)
                                                .map_err(|e| if let ChannelError::Close(msg) = e {
                                                        MsgHandleErrInternal::from_finish_shutdown(msg, chan.channel_id(), chan.get_user_id(), chan.force_shutdown(true), None)
                                                } else { unreachable!(); })
                                        , chan)
                                },
                                None => { return Err(APIError::ChannelUnavailable { err: "No such channel".to_owned() }) },
                        };
                        match handle_error!(self, res, chan.get_counterparty_node_id()) {
                                Ok(funding_msg) => {
                                        (chan, funding_msg)
                                },
                                Err(_) => { return Err(APIError::ChannelUnavailable {
                                        err: "Error deriving keys or signing initial commitment transactions - either our RNG or our counterparty's RNG is broken or the Signer refused to sign".to_owned()
                                }) },
                        }
                };

                let mut channel_state = self.channel_state.lock().unwrap();
                channel_state.pending_msg_events.push(events::MessageSendEvent::SendFundingCreated {
                        node_id: chan.get_counterparty_node_id(),
                        msg,
                });
                match channel_state.by_id.entry(chan.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.channel_id(), chan.get_counterparty_node_id()).is_some() {
                                        panic!("id_to_peer map already contained funding txid, which shouldn't be possible");
                                }
                                e.insert(chan);
                        }
                }
                Ok(())
        }

        #[cfg(test)]
        pub(crate) fn funding_transaction_generated_unchecked(&self, temporary_channel_id: &[u8; 32], 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, |_, 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::util::events::Event::FundingGenerationReady
        /// [`Event::ChannelClosed`]: crate::util::events::Event::ChannelClosed
        pub fn funding_transaction_generated(&self, temporary_channel_id: &[u8; 32], counterparty_node_id: &PublicKey, funding_transaction: Transaction) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                for inp in funding_transaction.input.iter() {
                        if inp.witness.is_empty() {
                                return Err(APIError::APIMisuseError {
                                        err: "Funding transaction must be fully signed and spend Segwit outputs".to_owned()
                                });
                        }
                }
                {
                        let height = self.best_block.read().unwrap().height();
                        // Transactions are evaluated as final by network mempools at the next block. However, the modules
                        // constituting our Lightning node might not have perfect sync about their blockchain views. Thus, if
                        // the wallet module is in advance on the LDK view, allow one more block of headroom.
                        if !funding_transaction.input.iter().all(|input| input.sequence == Sequence::MAX) && LockTime::from(funding_transaction.lock_time).is_block_height() && funding_transaction.lock_time.0 > height + 2 {
                                return Err(APIError::APIMisuseError {
                                        err: "Funding transaction absolute timelock is non-final".to_owned()
                                });
                        }
                }
                self.funding_transaction_generated_intern(temporary_channel_id, counterparty_node_id, funding_transaction, |chan, tx| {
                        let mut output_index = None;
                        let expected_spk = chan.get_funding_redeemscript().to_v0_p2wsh();
                        for (idx, outp) in tx.output.iter().enumerate() {
                                if outp.script_pubkey == expected_spk && outp.value == chan.get_value_satoshis() {
                                        if output_index.is_some() {
                                                return Err(APIError::APIMisuseError {
                                                        err: "Multiple outputs matched the expected script and value".to_owned()
                                                });
                                        }
                                        if idx > u16::max_value() as usize {
                                                return Err(APIError::APIMisuseError {
                                                        err: "Transaction had more than 2^16 outputs, which is not supported".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()
                                });
                        }
                        Ok(OutPoint { txid: tx.txid(), index: output_index.unwrap() })
                })
        }

        /// 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: &[[u8; 32]], config: &ChannelConfig,
        ) -> Result<(), APIError> {
                if config.cltv_expiry_delta < MIN_CLTV_EXPIRY_DELTA {
                        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.total_consistency_lock, &self.persistence_notifier,
                );
                {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        for channel_id in channel_ids {
                                let channel_counterparty_node_id = channel_state.by_id.get(channel_id)
                                        .ok_or(APIError::ChannelUnavailable {
                                                err: format!("Channel with ID {} was not found", log_bytes!(*channel_id)),
                                        })?
                                        .get_counterparty_node_id();
                                if channel_counterparty_node_id != *counterparty_node_id {
                                        return Err(APIError::APIMisuseError {
                                                err: "counterparty node id mismatch".to_owned(),
                                        });
                                }
                        }
                        for channel_id in channel_ids {
                                let channel = channel_state.by_id.get_mut(channel_id).unwrap();
                                if !channel.update_config(config) {
                                        continue;
                                }
                                if let Ok(msg) = self.get_channel_update_for_broadcast(channel) {
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate { msg });
                                } else if let Ok(msg) = self.get_channel_update_for_unicast(channel) {
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendChannelUpdate {
                                                node_id: channel.get_counterparty_node_id(),
                                                msg,
                                        });
                                }
                        }
                }
                Ok(())
        }

        /// 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.
        ///
        /// 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
        // 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: &[u8; 32], _next_node_id: PublicKey, amt_to_forward_msat: u64) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                let next_hop_scid = match self.channel_state.lock().unwrap().by_id.get(next_hop_channel_id) {
                        Some(chan) => {
                                if !chan.is_usable() {
                                        return Err(APIError::ChannelUnavailable {
                                                err: format!("Channel with id {} not fully established", log_bytes!(*next_hop_channel_id))
                                        })
                                }
                                chan.get_short_channel_id().unwrap_or(chan.outbound_scid_alias())
                        },
                        None => return Err(APIError::ChannelUnavailable {
                                err: format!("Channel with id {} not found", log_bytes!(*next_hop_channel_id))
                        })
                };

                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 pending_htlc_info = PendingHTLCInfo {
                        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.total_consistency_lock, &self.persistence_notifier);

                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,
                                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.total_consistency_lock, &self.persistence_notifier);

                let mut new_events = Vec::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, incoming_amt_msat: _
                                                                                }
                                                                        }) => {
                                                                                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,
                                                                                                        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_secret_res = self.keys_manager.get_node_secret(Recipient::PhantomNode);
                                                                                        if phantom_secret_res.is_ok() && fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, short_chan_id, &self.genesis_hash) {
                                                                                                let phantom_shared_secret = SharedSecret::new(&onion_packet.public_key.unwrap(), &phantom_secret_res.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) {
                                                                                                        Ok(res) => res,
                                                                                                        Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
                                                                                                                let sha256_of_onion = Sha256::hash(&onion_packet.hop_data).into_inner();
                                                                                                                // 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) => {
                                                                                                                match self.construct_recv_pending_htlc_info(hop_data, incoming_shared_secret, payment_hash, outgoing_amt_msat, outgoing_cltv_value, Some(phantom_shared_secret)) {
                                                                                                                        Ok(info) => phantom_receives.push((prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, vec![(info, prev_htlc_id)])),
                                                                                                                        Err(ReceiveError { 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 forward_chan_id = match self.short_to_chan_info.read().unwrap().get(&short_chan_id) {
                                                Some((_cp_id, chan_id)) => chan_id.clone(),
                                                None => {
                                                        forwarding_channel_not_found!();
                                                        continue;
                                                }
                                        };
                                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                                        let channel_state = &mut *channel_state_lock;
                                        match channel_state.by_id.entry(forward_chan_id) {
                                                hash_map::Entry::Vacant(_) => {
                                                        forwarding_channel_not_found!();
                                                        continue;
                                                },
                                                hash_map::Entry::Occupied(mut chan) => {
                                                        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, .. }, incoming_amt_msat: _,
                                                                                },
                                                                        }) => {
                                                                                log_trace!(self.logger, "Adding HTLC from short id {} with payment_hash {} to channel with short id {} after delay", prev_short_channel_id, log_bytes!(payment_hash.0), short_chan_id);
                                                                                let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                                                                        short_channel_id: prev_short_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.get_mut().queue_add_htlc(outgoing_amt_msat,
                                                                                        payment_hash, outgoing_cltv_value, htlc_source.clone(),
                                                                                        onion_packet, &self.logger)
                                                                                {
                                                                                        if let ChannelError::Ignore(msg) = e {
                                                                                                log_trace!(self.logger, "Failed to forward HTLC with payment_hash {}: {}", log_bytes!(payment_hash.0), 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.get());
                                                                                        failed_forwards.push((htlc_source, payment_hash,
                                                                                                HTLCFailReason::reason(failure_code, data),
                                                                                                HTLCDestination::NextHopChannel { node_id: Some(chan.get().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.get_mut().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 {
                                        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, ..
                                                                }
                                                        }) => {
                                                                let (cltv_expiry, onion_payload, payment_data, phantom_shared_secret) = match routing {
                                                                        PendingHTLCRouting::Receive { payment_data, incoming_cltv_expiry, phantom_shared_secret } => {
                                                                                let _legacy_hop_data = Some(payment_data.clone());
                                                                                (incoming_cltv_expiry, OnionPayload::Invoice { _legacy_hop_data }, Some(payment_data), phantom_shared_secret)
                                                                        },
                                                                        PendingHTLCRouting::ReceiveKeysend { payment_preimage, incoming_cltv_expiry } =>
                                                                                (incoming_cltv_expiry, OnionPayload::Spontaneous(payment_preimage), None, None),
                                                                        _ => {
                                                                                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,
                                                                                outpoint: prev_funding_outpoint,
                                                                                htlc_id: prev_htlc_id,
                                                                                incoming_packet_shared_secret: incoming_shared_secret,
                                                                                phantom_shared_secret,
                                                                        },
                                                                        value: outgoing_amt_msat,
                                                                        timer_ticks: 0,
                                                                        total_msat: if let Some(data) = &payment_data { data.total_msat } else { outgoing_amt_msat },
                                                                        cltv_expiry,
                                                                        onion_payload,
                                                                };

                                                                macro_rules! fail_htlc {
                                                                        ($htlc: expr, $payment_hash: expr) => {
                                                                                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,
                                                                                                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 },
                                                                                ));
                                                                        }
                                                                }
                                                                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.keys_manager.get_node_id(Recipient::PhantomNode)
                                                                                .expect("Failed to get node_id for phantom node recipient");
                                                                }

                                                                macro_rules! check_total_value {
                                                                        ($payment_data: expr, $payment_preimage: expr) => {{
                                                                                let mut payment_claimable_generated = false;
                                                                                let purpose = || {
                                                                                        events::PaymentPurpose::InvoicePayment {
                                                                                                payment_preimage: $payment_preimage,
                                                                                                payment_secret: $payment_data.payment_secret,
                                                                                        }
                                                                                };
                                                                                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);
                                                                                        continue
                                                                                }
                                                                                let (_, htlcs) = claimable_payments.claimable_htlcs.entry(payment_hash)
                                                                                        .or_insert_with(|| (purpose(), Vec::new()));
                                                                                if htlcs.len() == 1 {
                                                                                        if let OnionPayload::Spontaneous(_) = htlcs[0].onion_payload {
                                                                                                log_trace!(self.logger, "Failing new HTLC with payment_hash {} as we already had an existing keysend HTLC with the same payment hash", log_bytes!(payment_hash.0));
                                                                                                fail_htlc!(claimable_htlc, payment_hash);
                                                                                                continue
                                                                                        }
                                                                                }
                                                                                let mut total_value = claimable_htlc.value;
                                                                                for htlc in htlcs.iter() {
                                                                                        total_value += htlc.value;
                                                                                        match &htlc.onion_payload {
                                                                                                OnionPayload::Invoice { .. } => {
                                                                                                        if htlc.total_msat != $payment_data.total_msat {
                                                                                                                log_trace!(self.logger, "Failing HTLCs with payment_hash {} as the HTLCs had inconsistent total values (eg {} and {})",
                                                                                                                        log_bytes!(payment_hash.0), $payment_data.total_msat, htlc.total_msat);
                                                                                                                total_value = msgs::MAX_VALUE_MSAT;
                                                                                                        }
                                                                                                        if total_value >= msgs::MAX_VALUE_MSAT { break; }
                                                                                                },
                                                                                                _ => unreachable!(),
                                                                                        }
                                                                                }
                                                                                if total_value >= msgs::MAX_VALUE_MSAT || total_value > $payment_data.total_msat {
                                                                                        log_trace!(self.logger, "Failing HTLCs with payment_hash {} as the total value {} ran over expected value {} (or HTLCs were inconsistent)",
                                                                                                log_bytes!(payment_hash.0), total_value, $payment_data.total_msat);
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                } else if total_value == $payment_data.total_msat {
                                                                                        let prev_channel_id = prev_funding_outpoint.to_channel_id();
                                                                                        htlcs.push(claimable_htlc);
                                                                                        new_events.push(events::Event::PaymentClaimable {
                                                                                                receiver_node_id: Some(receiver_node_id),
                                                                                                payment_hash,
                                                                                                purpose: purpose(),
                                                                                                amount_msat: total_value,
                                                                                                via_channel_id: Some(prev_channel_id),
                                                                                                via_user_channel_id: Some(prev_user_channel_id),
                                                                                        });
                                                                                        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);
                                                                                }
                                                                                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 = match inbound_payment::verify(payment_hash, &payment_data, self.highest_seen_timestamp.load(Ordering::Acquire) as u64, &self.inbound_payment_key, &self.logger) {
                                                                                                        Ok(payment_preimage) => payment_preimage,
                                                                                                        Err(()) => {
                                                                                                                fail_htlc!(claimable_htlc, payment_hash);
                                                                                                                continue
                                                                                                        }
                                                                                                };
                                                                                                check_total_value!(payment_data, payment_preimage);
                                                                                        },
                                                                                        OnionPayload::Spontaneous(preimage) => {
                                                                                                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);
                                                                                                        continue
                                                                                                }
                                                                                                match claimable_payments.claimable_htlcs.entry(payment_hash) {
                                                                                                        hash_map::Entry::Vacant(e) => {
                                                                                                                let purpose = events::PaymentPurpose::SpontaneousPayment(preimage);
                                                                                                                e.insert((purpose.clone(), vec![claimable_htlc]));
                                                                                                                let prev_channel_id = prev_funding_outpoint.to_channel_id();
                                                                                                                new_events.push(events::Event::PaymentClaimable {
                                                                                                                        receiver_node_id: Some(receiver_node_id),
                                                                                                                        payment_hash,
                                                                                                                        amount_msat: outgoing_amt_msat,
                                                                                                                        purpose,
                                                                                                                        via_channel_id: Some(prev_channel_id),
                                                                                                                        via_user_channel_id: Some(prev_user_channel_id),
                                                                                                                });
                                                                                                        },
                                                                                                        hash_map::Entry::Occupied(_) => {
                                                                                                                log_trace!(self.logger, "Failing new keysend HTLC with payment_hash {} for a duplicative payment hash", log_bytes!(payment_hash.0));
                                                                                                                fail_htlc!(claimable_htlc, payment_hash);
                                                                                                        }
                                                                                                }
                                                                                        }
                                                                                }
                                                                        },
                                                                        hash_map::Entry::Occupied(inbound_payment) => {
                                                                                if payment_data.is_none() {
                                                                                        log_trace!(self.logger, "Failing new keysend HTLC with payment_hash {} because we already have an inbound payment with the same payment hash", log_bytes!(payment_hash.0));
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                        continue
                                                                                };
                                                                                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.", log_bytes!(payment_hash.0));
                                                                                        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 {}).",
                                                                                                log_bytes!(payment_hash.0), payment_data.total_msat, inbound_payment.get().min_value_msat.unwrap());
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                } else {
                                                                                        let payment_claimable_generated = check_total_value!(payment_data, inbound_payment.get().payment_preimage);
                                                                                        if payment_claimable_generated {
                                                                                                inbound_payment.remove_entry();
                                                                                        }
                                                                                }
                                                                        },
                                                                };
                                                        },
                                                        HTLCForwardInfo::FailHTLC { .. } => {
                                                                panic!("Got pending fail of our own HTLC");
                                                        }
                                                }
                                        }
                                }
                        }
                }

                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 timer_tick_occurred.
        ///
        /// Exposed for testing to allow us to process events quickly without generating accidental
        /// BroadcastChannelUpdate events in timer_tick_occurred.
        ///
        /// Expects the caller to have a total_consistency_lock read lock.
        fn process_background_events(&self) -> bool {
                let mut background_events = Vec::new();
                mem::swap(&mut *self.pending_background_events.lock().unwrap(), &mut background_events);
                if background_events.is_empty() {
                        return false;
                }

                for event in background_events.drain(..) {
                        match event {
                                BackgroundEvent::ClosingMonitorUpdate((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);
                                },
                        }
                }
                true
        }

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

        fn update_channel_fee(&self, chan_id: &[u8; 32], chan: &mut Channel<<K::Target as KeysInterface>::Signer>, new_feerate: u32) -> NotifyOption {
                if !chan.is_outbound() { return NotifyOption::SkipPersist; }
                // If the feerate has decreased by less than half, don't bother
                if new_feerate <= chan.get_feerate() && new_feerate * 2 > chan.get_feerate() {
                        log_trace!(self.logger, "Channel {} does not qualify for a feerate change from {} to {}.",
                                log_bytes!(chan_id[..]), chan.get_feerate(), new_feerate);
                        return NotifyOption::SkipPersist;
                }
                if !chan.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).",
                                log_bytes!(chan_id[..]), chan.get_feerate(), new_feerate);
                        return NotifyOption::SkipPersist;
                }
                log_trace!(self.logger, "Channel {} qualifies for a feerate change from {} to {}.",
                        log_bytes!(chan_id[..]), chan.get_feerate(), new_feerate);

                chan.queue_update_fee(new_feerate, &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.total_consistency_lock, &self.persistence_notifier, || {
                        let mut should_persist = NotifyOption::SkipPersist;

                        let new_feerate = self.fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Normal);

                        let mut channel_state = self.channel_state.lock().unwrap();
                        for (chan_id, chan) in channel_state.by_id.iter_mut() {
                                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
                });
        }

        fn remove_stale_resolved_payments(&self) {
                // If an outbound payment was completed, and no pending HTLCs remain, we should remove it
                // from the map. However, if we did that immediately when the last payment HTLC is claimed,
                // this could race the user making a duplicate send_payment call and our idempotency
                // guarantees would be violated. Instead, we wait a few timer ticks to do the actual
                // removal. This should be more than sufficient to ensure the idempotency of any
                // `send_payment` calls that were made at the same time the `PaymentSent` event was being
                // processed.
                let mut pending_outbound_payments = self.pending_outbound_payments.lock().unwrap();
                let pending_events = self.pending_events.lock().unwrap();
                pending_outbound_payments.retain(|payment_id, payment| {
                        if let PendingOutboundPayment::Fulfilled { session_privs, timer_ticks_without_htlcs, .. } = payment {
                                let mut no_remaining_entries = session_privs.is_empty();
                                if no_remaining_entries {
                                        for ev in pending_events.iter() {
                                                match ev {
                                                        events::Event::PaymentSent { payment_id: Some(ev_payment_id), .. } |
                                                        events::Event::PaymentPathSuccessful { payment_id: ev_payment_id, .. } |
                                                        events::Event::PaymentPathFailed { payment_id: Some(ev_payment_id), .. } => {
                                                                if payment_id == ev_payment_id {
                                                                        no_remaining_entries = false;
                                                                        break;
                                                                }
                                                        },
                                                        _ => {},
                                                }
                                        }
                                }
                                if no_remaining_entries {
                                        *timer_ticks_without_htlcs += 1;
                                        *timer_ticks_without_htlcs <= IDEMPOTENCY_TIMEOUT_TICKS
                                } else {
                                        *timer_ticks_without_htlcs = 0;
                                        true
                                }
                        } else { true }
                });
        }

        /// 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`.
        ///
        /// Note that this may cause reentrancy through `chain::Watch::update_channel` calls or feerate
        /// estimate fetches.
        pub fn timer_tick_occurred(&self) {
                PersistenceNotifierGuard::optionally_notify(&self.total_consistency_lock, &self.persistence_notifier, || {
                        let mut should_persist = NotifyOption::SkipPersist;
                        if self.process_background_events() { should_persist = NotifyOption::DoPersist; }

                        let new_feerate = self.fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Normal);

                        let mut handle_errors: Vec<(Result<(), _>, _)> = Vec::new();
                        let mut timed_out_mpp_htlcs = Vec::new();
                        {
                                let mut channel_state_lock = self.channel_state.lock().unwrap();
                                let channel_state = &mut *channel_state_lock;
                                let pending_msg_events = &mut channel_state.pending_msg_events;
                                channel_state.by_id.retain(|chan_id, chan| {
                                        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_err!(self, e, chan, chan_id);
                                                handle_errors.push((Err(err), chan.get_counterparty_node_id()));
                                                if needs_close { return false; }
                                        }

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

                                        chan.maybe_expire_prev_config();

                                        true
                                });
                        }

                        self.claimable_payments.lock().unwrap().claimable_htlcs.retain(|payment_hash, (_, htlcs)| {
                                if htlcs.is_empty() {
                                        // This should be unreachable
                                        debug_assert!(false);
                                        return false;
                                }
                                if let OnionPayload::Invoice { .. } = 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.
                                        if htlcs[0].total_msat == htlcs.iter().fold(0, |total, htlc| total + htlc.value) {
                                                return true;
                                        } else if htlcs.into_iter().any(|htlc| {
                                                htlc.timer_ticks += 1;
                                                return htlc.timer_ticks >= MPP_TIMEOUT_TICKS
                                        }) {
                                                timed_out_mpp_htlcs.extend(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);
                        }

                        self.remove_stale_resolved_payments();

                        // 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) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                let removed_source = self.claimable_payments.lock().unwrap().claimable_htlcs.remove(payment_hash);
                if let Some((_, mut sources)) = removed_source {
                        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: *payment_hash };
                                self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
                        }
                }
        }

        /// 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<<K::Target as KeysInterface>::Signer>) -> (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.should_announce() {
                        chan.get_short_channel_id().or(chan.latest_inbound_scid_alias())
                } else {
                        chan.latest_inbound_scid_alias().or(chan.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<<K::Target as KeysInterface>::Signer>) -> (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: [u8; 32],
                counterparty_node_id: &PublicKey
        ) {
                let (failure_code, onion_failure_data) =
                        match self.channel_state.lock().unwrap().by_id.entry(channel_id) {
                                hash_map::Entry::Occupied(chan_entry) => {
                                        self.get_htlc_inbound_temp_fail_err_and_data(0x1000|7, &chan_entry.get())
                                },
                                hash_map::Entry::Vacant(_) => (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) {
                #[cfg(debug_assertions)]
                {
                        // Ensure that the `channel_state` lock is not 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 `channel_state` lock, which calling this
                        // function with the `channel_state` locked would.
                        assert!(self.channel_state.try_lock().is_ok());
                }

                //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, ref payment_params, .. } => {
                                let mut session_priv_bytes = [0; 32];
                                session_priv_bytes.copy_from_slice(&session_priv[..]);
                                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                                let mut all_paths_failed = false;
                                let mut full_failure_ev = None;
                                if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(*payment_id) {
                                        if !payment.get_mut().remove(&session_priv_bytes, Some(&path)) {
                                                log_trace!(self.logger, "Received duplicative fail for HTLC with payment_hash {}", log_bytes!(payment_hash.0));
                                                return;
                                        }
                                        if payment.get().is_fulfilled() {
                                                log_trace!(self.logger, "Received failure of HTLC with payment_hash {} after payment completion", log_bytes!(payment_hash.0));
                                                return;
                                        }
                                        if payment.get().remaining_parts() == 0 {
                                                all_paths_failed = true;
                                                if payment.get().abandoned() {
                                                        full_failure_ev = Some(events::Event::PaymentFailed {
                                                                payment_id: *payment_id,
                                                                payment_hash: payment.get().payment_hash().expect("PendingOutboundPayments::RetriesExceeded always has a payment hash set"),
                                                        });
                                                        payment.remove();
                                                }
                                        }
                                } else {
                                        log_trace!(self.logger, "Received duplicative fail for HTLC with payment_hash {}", log_bytes!(payment_hash.0));
                                        return;
                                }
                                let mut retry = if let Some(payment_params_data) = payment_params {
                                        let path_last_hop = path.last().expect("Outbound payments must have had a valid path");
                                        Some(RouteParameters {
                                                payment_params: payment_params_data.clone(),
                                                final_value_msat: path_last_hop.fee_msat,
                                                final_cltv_expiry_delta: path_last_hop.cltv_expiry_delta,
                                        })
                                } else { None };
                                log_trace!(self.logger, "Failing outbound payment HTLC with payment_hash {}", log_bytes!(payment_hash.0));

                                let path_failure = {
#[cfg(test)]
                                        let (network_update, short_channel_id, payment_retryable, onion_error_code, onion_error_data) = onion_error.decode_onion_failure(&self.secp_ctx, &self.logger, &source);
#[cfg(not(test))]
                                        let (network_update, short_channel_id, payment_retryable, _, _) = onion_error.decode_onion_failure(&self.secp_ctx, &self.logger, &source);

                                        if self.payment_is_probe(payment_hash, &payment_id) {
                                                if !payment_retryable {
                                                        events::Event::ProbeSuccessful {
                                                                payment_id: *payment_id,
                                                                payment_hash: payment_hash.clone(),
                                                                path: path.clone(),
                                                        }
                                                } else {
                                                        events::Event::ProbeFailed {
                                                                payment_id: *payment_id,
                                                                payment_hash: payment_hash.clone(),
                                                                path: path.clone(),
                                                                short_channel_id,
                                                        }
                                                }
                                        } else {
                                                // TODO: If we decided to blame ourselves (or one of our channels) in
                                                // process_onion_failure we should close that channel as it implies our
                                                // next-hop is needlessly blaming us!
                                                if let Some(scid) = short_channel_id {
                                                        retry.as_mut().map(|r| r.payment_params.previously_failed_channels.push(scid));
                                                }
                                                events::Event::PaymentPathFailed {
                                                        payment_id: Some(*payment_id),
                                                        payment_hash: payment_hash.clone(),
                                                        payment_failed_permanently: !payment_retryable,
                                                        network_update,
                                                        all_paths_failed,
                                                        path: path.clone(),
                                                        short_channel_id,
                                                        retry,
                                                        #[cfg(test)]
                                                        error_code: onion_error_code,
                                                        #[cfg(test)]
                                                        error_data: onion_error_data
                                                }
                                        }
                                };
                                let mut pending_events = self.pending_events.lock().unwrap();
                                pending_events.push(path_failure);
                                if let Some(ev) = full_failure_ev { pending_events.push(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 {:?}", log_bytes!(payment_hash.0), onion_error);
                                let err_packet = onion_error.get_encrypted_failure_packet(incoming_packet_shared_secret, phantom_shared_secret);

                                let mut forward_event = None;
                                let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
                                if forward_htlcs.is_empty() {
                                        forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS));
                                }
                                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);
                                let mut pending_events = self.pending_events.lock().unwrap();
                                if let Some(time) = forward_event {
                                        pending_events.push(events::Event::PendingHTLCsForwardable {
                                                time_forwardable: time
                                        });
                                }
                                pending_events.push(events::Event::HTLCHandlingFailed {
                                        prev_channel_id: outpoint.to_channel_id(),
                                        failed_next_destination: destination,
                                });
                        },
                }
        }

        /// Provides a payment preimage in response to [`Event::PaymentClaimable`], generating any
        /// [`MessageSendEvent`]s needed to claim the payment.
        ///
        /// Note that calling this method does *not* guarantee that the payment has been claimed. You
        /// *must* wait for an [`Event::PaymentClaimed`] event which upon a successful claim will be
        /// provided to your [`EventHandler`] when [`process_pending_events`] is next called.
        ///
        /// 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.
        ///
        /// [`Event::PaymentClaimable`]: crate::util::events::Event::PaymentClaimable
        /// [`Event::PaymentClaimed`]: crate::util::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
        pub fn claim_funds(&self, payment_preimage: PaymentPreimage) {
                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());

                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

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

                                let dup_purpose = claimable_payments.pending_claiming_payments.insert(payment_hash,
                                        ClaimingPayment { amount_msat: sources.iter().map(|source| source.value).sum(),
                                        payment_purpose, receiver_node_id,
                                });
                                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",
                                                log_bytes!(payment_hash.0));
                                }
                                sources
                        } else { return; }
                };
                debug_assert!(!sources.is_empty());

                // If we are claiming an MPP payment, we check that all channels which contain a claimable
                // HTLC still exist. While this isn't guaranteed to remain true if a channel closes while
                // we're claiming (or even after we claim, before the commitment update dance completes),
                // it should be a relatively rare race, and we'd rather not claim HTLCs that require us to
                // go on-chain (and lose the on-chain fee to do so) than just reject the payment.
                //
                // Note that we'll still always get our funds - as long as the generated
                // `ChannelMonitorUpdate` makes it out to the relevant monitor we can claim on-chain.
                //
                // If we find an HTLC which we would need to claim but for which we do not have a
                // channel, we will fail all parts of the MPP payment. While we could wait and see if
                // the sender retries the already-failed path(s), it should be a pretty rare case where
                // we got all the HTLCs and then a channel closed while we were waiting for the user to
                // provide the preimage, so worrying too much about the optimal handling isn't worth
                // it.
                let mut claimable_amt_msat = 0;
                let mut expected_amt_msat = None;
                let mut valid_mpp = true;
                let mut errs = Vec::new();
                let mut channel_state = Some(self.channel_state.lock().unwrap());
                for htlc in sources.iter() {
                        let chan_id = match self.short_to_chan_info.read().unwrap().get(&htlc.prev_hop.short_channel_id) {
                                Some((_cp_id, chan_id)) => chan_id.clone(),
                                None => {
                                        valid_mpp = false;
                                        break;
                                }
                        };

                        if let None = channel_state.as_ref().unwrap().by_id.get(&chan_id) {
                                valid_mpp = false;
                                break;
                        }

                        if expected_amt_msat.is_some() && expected_amt_msat != Some(htlc.total_msat) {
                                log_error!(self.logger, "Somehow ended up with an MPP payment with different total amounts - this should not be reachable!");
                                debug_assert!(false);
                                valid_mpp = false;
                                break;
                        }
                        expected_amt_msat = Some(htlc.total_msat);
                        if let OnionPayload::Spontaneous(_) = &htlc.onion_payload {
                                // We don't currently support MPP for spontaneous payments, so just check
                                // that there's one payment here and move on.
                                if sources.len() != 1 {
                                        log_error!(self.logger, "Somehow ended up with an MPP spontaneous payment - this should not be reachable!");
                                        debug_assert!(false);
                                        valid_mpp = false;
                                        break;
                                }
                        }

                        claimable_amt_msat += htlc.value;
                }
                if sources.is_empty() || expected_amt_msat.is_none() {
                        mem::drop(channel_state);
                        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() {
                        mem::drop(channel_state);
                        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 channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap()); }
                                if let Err((pk, err)) = self.claim_funds_from_hop(channel_state.take().unwrap(), htlc.prev_hop,
                                        payment_preimage,
                                        |_| 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)); }
                                }
                        }
                }
                mem::drop(channel_state);
                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>) -> Option<MonitorUpdateCompletionAction>>(&self,
                mut channel_state_lock: MutexGuard<ChannelHolder<<K::Target as KeysInterface>::Signer>>,
                prev_hop: HTLCPreviousHopData, payment_preimage: PaymentPreimage, completion_action: ComplFunc)
        -> Result<(), (PublicKey, MsgHandleErrInternal)> {
                //TODO: Delay the claimed_funds relaying just like we do outbound relay!

                let chan_id = prev_hop.outpoint.to_channel_id();
                let channel_state = &mut *channel_state_lock;
                if let hash_map::Entry::Occupied(mut chan) = channel_state.by_id.entry(chan_id) {
                        let counterparty_node_id = chan.get().get_counterparty_node_id();
                        match chan.get_mut().get_update_fulfill_htlc_and_commit(prev_hop.htlc_id, payment_preimage, &self.logger) {
                                Ok(msgs_monitor_option) => {
                                        if let UpdateFulfillCommitFetch::NewClaim { msgs, htlc_value_msat, monitor_update } = msgs_monitor_option {
                                                match self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                        ChannelMonitorUpdateStatus::Completed => {},
                                                        e => {
                                                                log_given_level!(self.logger, if e == ChannelMonitorUpdateStatus::PermanentFailure { Level::Error } else { Level::Debug },
                                                                        "Failed to update channel monitor with preimage {:?}: {:?}",
                                                                        payment_preimage, e);
                                                                let err = handle_monitor_update_res!(self, e, chan, RAACommitmentOrder::CommitmentFirst, false, msgs.is_some()).unwrap_err();
                                                                mem::drop(channel_state_lock);
                                                                self.handle_monitor_update_completion_actions(completion_action(Some(htlc_value_msat)));
                                                                return Err((counterparty_node_id, err));
                                                        }
                                                }
                                                if let Some((msg, commitment_signed)) = msgs {
                                                        log_debug!(self.logger, "Claiming funds for HTLC with preimage {} resulted in a commitment_signed for channel {}",
                                                                log_bytes!(payment_preimage.0), log_bytes!(chan.get().channel_id()));
                                                        channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                                node_id: chan.get().get_counterparty_node_id(),
                                                                updates: msgs::CommitmentUpdate {
                                                                        update_add_htlcs: Vec::new(),
                                                                        update_fulfill_htlcs: vec![msg],
                                                                        update_fail_htlcs: Vec::new(),
                                                                        update_fail_malformed_htlcs: Vec::new(),
                                                                        update_fee: None,
                                                                        commitment_signed,
                                                                }
                                                        });
                                                }
                                                mem::drop(channel_state_lock);
                                                self.handle_monitor_update_completion_actions(completion_action(Some(htlc_value_msat)));
                                                Ok(())
                                        } else {
                                                Ok(())
                                        }
                                },
                                Err((e, monitor_update)) => {
                                        match self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                ChannelMonitorUpdateStatus::Completed => {},
                                                e => {
                                                        // 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 update and try
                                                        // again on restart.
                                                        log_given_level!(self.logger, if e == ChannelMonitorUpdateStatus::PermanentFailure { Level::Error } else { Level::Info },
                                                                "Failed to update channel monitor with preimage {:?} immediately prior to force-close: {:?}",
                                                                payment_preimage, e);
                                                },
                                        }
                                        let (drop, res) = convert_chan_err!(self, e, chan.get_mut(), &chan_id);
                                        if drop {
                                                chan.remove_entry();
                                        }
                                        mem::drop(channel_state_lock);
                                        self.handle_monitor_update_completion_actions(completion_action(None));
                                        Err((counterparty_node_id, res))
                                },
                        }
                } else {
                        let preimage_update = ChannelMonitorUpdate {
                                update_id: CLOSED_CHANNEL_UPDATE_ID,
                                updates: vec![ChannelMonitorUpdateStep::PaymentPreimage {
                                        payment_preimage,
                                }],
                        };
                        // 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);
                        }
                        mem::drop(channel_state_lock);
                        // 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));
                        Ok(())
                }
        }

        fn finalize_claims(&self, mut sources: Vec<HTLCSource>) {
                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                let mut pending_events = self.pending_events.lock().unwrap();
                for source in sources.drain(..) {
                        if let HTLCSource::OutboundRoute { session_priv, payment_id, path, .. } = source {
                                let mut session_priv_bytes = [0; 32];
                                session_priv_bytes.copy_from_slice(&session_priv[..]);
                                if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(payment_id) {
                                        assert!(payment.get().is_fulfilled());
                                        if payment.get_mut().remove(&session_priv_bytes, None) {
                                                pending_events.push(
                                                        events::Event::PaymentPathSuccessful {
                                                                payment_id,
                                                                payment_hash: payment.get().payment_hash(),
                                                                path,
                                                        }
                                                );
                                        }
                                }
                        }
                }
        }

        fn claim_funds_internal(&self, channel_state_lock: MutexGuard<ChannelHolder<<K::Target as KeysInterface>::Signer>>, source: HTLCSource, payment_preimage: PaymentPreimage, forwarded_htlc_value_msat: Option<u64>, from_onchain: bool, next_channel_id: [u8; 32]) {
                match source {
                        HTLCSource::OutboundRoute { session_priv, payment_id, path, .. } => {
                                mem::drop(channel_state_lock);
                                let mut session_priv_bytes = [0; 32];
                                session_priv_bytes.copy_from_slice(&session_priv[..]);
                                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                                if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(payment_id) {
                                        let mut pending_events = self.pending_events.lock().unwrap();
                                        if !payment.get().is_fulfilled() {
                                                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
                                                let fee_paid_msat = payment.get().get_pending_fee_msat();
                                                pending_events.push(
                                                        events::Event::PaymentSent {
                                                                payment_id: Some(payment_id),
                                                                payment_preimage,
                                                                payment_hash,
                                                                fee_paid_msat,
                                                        }
                                                );
                                                payment.get_mut().mark_fulfilled();
                                        }

                                        if from_onchain {
                                                // We currently immediately remove HTLCs which were fulfilled on-chain.
                                                // This could potentially lead to removing a pending payment too early,
                                                // with a reorg of one block causing us to re-add the fulfilled payment on
                                                // restart.
                                                // TODO: We should have a second monitor event that informs us of payments
                                                // irrevocably fulfilled.
                                                if payment.get_mut().remove(&session_priv_bytes, Some(&path)) {
                                                        let payment_hash = Some(PaymentHash(Sha256::hash(&payment_preimage.0).into_inner()));
                                                        pending_events.push(
                                                                events::Event::PaymentPathSuccessful {
                                                                        payment_id,
                                                                        payment_hash,
                                                                        path,
                                                                }
                                                        );
                                                }
                                        }
                                } else {
                                        log_trace!(self.logger, "Received duplicative fulfill for HTLC with payment_preimage {}", log_bytes!(payment_preimage.0));
                                }
                        },
                        HTLCSource::PreviousHopData(hop_data) => {
                                let prev_outpoint = hop_data.outpoint;
                                let res = self.claim_funds_from_hop(channel_state_lock, hop_data, payment_preimage,
                                        |htlc_claim_value_msat| {
                                                if let Some(forwarded_htlc_value) = forwarded_htlc_value_msat {
                                                        let fee_earned_msat = if let Some(claimed_htlc_value) = htlc_claim_value_msat {
                                                                Some(claimed_htlc_value - forwarded_htlc_value)
                                                        } else { None };

                                                        let prev_channel_id = Some(prev_outpoint.to_channel_id());
                                                        let next_channel_id = Some(next_channel_id);

                                                        Some(MonitorUpdateCompletionAction::EmitEvent { event: events::Event::PaymentForwarded {
                                                                fee_earned_msat,
                                                                claim_from_onchain_tx: from_onchain,
                                                                prev_channel_id,
                                                                next_channel_id,
                                                        }})
                                                } else { None }
                                        });
                                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) {
                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 }) = payment {
                                                self.pending_events.lock().unwrap().push(events::Event::PaymentClaimed {
                                                        payment_hash, purpose, amount_msat, receiver_node_id: Some(receiver_node_id),
                                                });
                                        }
                                },
                                MonitorUpdateCompletionAction::EmitEvent { event } => {
                                        self.pending_events.lock().unwrap().push(event);
                                },
                        }
                }
        }

        /// 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<<K::Target as KeysInterface>::Signer>, 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)>)> {
                let mut htlc_forwards = None;

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

                emit_channel_ready_event!(self, channel);

                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_transaction(&tx);
                }

                htlc_forwards
        }

        fn channel_monitor_updated(&self, funding_txo: &OutPoint, highest_applied_update_id: u64) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                let htlc_forwards;
                let (mut pending_failures, finalized_claims, counterparty_node_id) = {
                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        let mut channel = match channel_state.by_id.entry(funding_txo.to_channel_id()) {
                                hash_map::Entry::Occupied(chan) => chan,
                                hash_map::Entry::Vacant(_) => return,
                        };
                        if !channel.get().is_awaiting_monitor_update() || channel.get().get_latest_monitor_update_id() != highest_applied_update_id {
                                return;
                        }

                        let counterparty_node_id = channel.get().get_counterparty_node_id();
                        let updates = channel.get_mut().monitor_updating_restored(&self.logger, self.get_our_node_id(), self.genesis_hash, self.best_block.read().unwrap().height());
                        let channel_update = if updates.channel_ready.is_some() && channel.get().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(channel.get()) {
                                        Some(events::MessageSendEvent::SendChannelUpdate {
                                                node_id: channel.get().get_counterparty_node_id(),
                                                msg,
                                        })
                                } else { None }
                        } else { None };
                        htlc_forwards = self.handle_channel_resumption(&mut channel_state.pending_msg_events, channel.get_mut(), 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 {
                                channel_state.pending_msg_events.push(upd);
                        }

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

        /// 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: &[u8; 32], 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: &[u8; 32], 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: &[u8; 32], counterparty_node_id: &PublicKey, accept_0conf: bool, user_channel_id: u128) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                match channel_state.by_id.entry(temporary_channel_id.clone()) {
                        hash_map::Entry::Occupied(mut channel) => {
                                if !channel.get().inbound_is_awaiting_accept() {
                                        return Err(APIError::APIMisuseError { err: "The channel isn't currently awaiting to be accepted.".to_owned() });
                                }
                                if *counterparty_node_id != channel.get().get_counterparty_node_id() {
                                        return Err(APIError::APIMisuseError { err: "The passed counterparty_node_id doesn't match the channel's counterparty node_id".to_owned() });
                                }
                                if accept_0conf {
                                        channel.get_mut().set_0conf();
                                } else if channel.get().get_channel_type().requires_zero_conf() {
                                        let send_msg_err_event = events::MessageSendEvent::HandleError {
                                                node_id: channel.get().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(), }
                                                }
                                        };
                                        channel_state.pending_msg_events.push(send_msg_err_event);
                                        let _ = remove_channel!(self, channel);
                                        return Err(APIError::APIMisuseError { err: "Please use accept_inbound_channel_from_trusted_peer_0conf to accept channels with zero confirmations.".to_owned() });
                                }

                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
                                        node_id: channel.get().get_counterparty_node_id(),
                                        msg: channel.get_mut().accept_inbound_channel(user_channel_id),
                                });
                        }
                        hash_map::Entry::Vacant(_) => {
                                return Err(APIError::ChannelUnavailable { err: "Can't accept a channel that doesn't exist".to_owned() });
                        }
                }
                Ok(())
        }

        fn internal_open_channel(&self, counterparty_node_id: &PublicKey, their_features: InitFeatures, msg: &msgs::OpenChannel) -> Result<(), MsgHandleErrInternal> {
                if msg.chain_hash != self.genesis_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()));
                }

                let mut random_bytes = [0u8; 16];
                random_bytes.copy_from_slice(&self.keys_manager.get_secure_random_bytes()[..16]);
                let user_channel_id = u128::from_be_bytes(random_bytes);

                let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                let mut channel = match Channel::new_from_req(&self.fee_estimator, &self.keys_manager,
                        counterparty_node_id.clone(), &their_features, msg, user_channel_id, &self.default_configuration,
                        self.best_block.read().unwrap().height(), &self.logger, outbound_scid_alias)
                {
                        Err(e) => {
                                self.outbound_scid_aliases.lock().unwrap().remove(&outbound_scid_alias);
                                return Err(MsgHandleErrInternal::from_chan_no_close(e, msg.temporary_channel_id));
                        },
                        Ok(res) => res
                };
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                match channel_state.by_id.entry(channel.channel_id()) {
                        hash_map::Entry::Occupied(_) => {
                                self.outbound_scid_aliases.lock().unwrap().remove(&outbound_scid_alias);
                                return Err(MsgHandleErrInternal::send_err_msg_no_close("temporary_channel_id collision!".to_owned(), msg.temporary_channel_id.clone()))
                        },
                        hash_map::Entry::Vacant(entry) => {
                                if !self.default_configuration.manually_accept_inbound_channels {
                                        if channel.get_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()));
                                        }
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
                                                node_id: counterparty_node_id.clone(),
                                                msg: channel.accept_inbound_channel(user_channel_id),
                                        });
                                } else {
                                        let mut pending_events = self.pending_events.lock().unwrap();
                                        pending_events.push(
                                                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: channel.get_channel_type().clone(),
                                                }
                                        );
                                }

                                entry.insert(channel);
                        }
                }
                Ok(())
        }

        fn internal_accept_channel(&self, counterparty_node_id: &PublicKey, their_features: InitFeatures, msg: &msgs::AcceptChannel) -> Result<(), MsgHandleErrInternal> {
                let (value, output_script, user_id) = {
                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        match channel_state.by_id.entry(msg.temporary_channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
                                        if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.temporary_channel_id));
                                        }
                                        try_chan_entry!(self, chan.get_mut().accept_channel(&msg, &self.default_configuration.channel_handshake_limits, &their_features), chan);
                                        (chan.get().get_value_satoshis(), chan.get().get_funding_redeemscript().to_v0_p2wsh(), chan.get().get_user_id())
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.temporary_channel_id))
                        }
                };
                let mut pending_events = self.pending_events.lock().unwrap();
                pending_events.push(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,
                });
                Ok(())
        }

        fn internal_funding_created(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingCreated) -> Result<(), MsgHandleErrInternal> {
                let ((funding_msg, monitor, mut channel_ready), mut chan) = {
                        let best_block = *self.best_block.read().unwrap();
                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        match channel_state.by_id.entry(msg.temporary_channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan) => {
                                        if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.temporary_channel_id));
                                        }
                                        (try_chan_entry!(self, chan.get_mut().funding_created(msg, best_block, &self.keys_manager, &self.logger), chan), chan.remove())
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.temporary_channel_id))
                        }
                };
                // Because we have exclusive ownership of the channel here we can release the channel_state
                // lock before watch_channel
                match self.chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor) {
                        ChannelMonitorUpdateStatus::Completed => {},
                        ChannelMonitorUpdateStatus::PermanentFailure => {
                                // Note that we reply with the new channel_id in error messages if we gave up on the
                                // channel, not the temporary_channel_id. This is compatible with ourselves, but the
                                // spec is somewhat ambiguous here. Not a huge deal since we'll send error messages for
                                // any messages referencing a previously-closed channel anyway.
                                // We do not propagate the monitor update to the user as it would be for a monitor
                                // that we didn't manage to store (and that we don't care about - we don't respond
                                // with the funding_signed so the channel can never go on chain).
                                let (_monitor_update, failed_htlcs) = chan.force_shutdown(false);
                                assert!(failed_htlcs.is_empty());
                                return Err(MsgHandleErrInternal::send_err_msg_no_close("ChannelMonitor storage failure".to_owned(), funding_msg.channel_id));
                        },
                        ChannelMonitorUpdateStatus::InProgress => {
                                // 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.
                                chan.monitor_updating_paused(false, false, channel_ready.is_some(), Vec::new(), Vec::new(), Vec::new());
                                channel_ready = None; // Don't send the channel_ready now
                        },
                }
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                match channel_state.by_id.entry(funding_msg.channel_id) {
                        hash_map::Entry::Occupied(_) => {
                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Already had channel with the new channel_id".to_owned(), funding_msg.channel_id))
                        },
                        hash_map::Entry::Vacant(e) => {
                                let mut id_to_peer = self.id_to_peer.lock().unwrap();
                                match id_to_peer.entry(chan.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(),
                                                        funding_msg.channel_id))
                                        },
                                        hash_map::Entry::Vacant(i_e) => {
                                                i_e.insert(chan.get_counterparty_node_id());
                                        }
                                }
                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendFundingSigned {
                                        node_id: counterparty_node_id.clone(),
                                        msg: funding_msg,
                                });
                                if let Some(msg) = channel_ready {
                                        send_channel_ready!(self, channel_state.pending_msg_events, chan, msg);
                                }
                                e.insert(chan);
                        }
                }
                Ok(())
        }

        fn internal_funding_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingSigned) -> Result<(), MsgHandleErrInternal> {
                let funding_tx = {
                        let best_block = *self.best_block.read().unwrap();
                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        match channel_state.by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
                                        if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }
                                        let (monitor, funding_tx, channel_ready) = match chan.get_mut().funding_signed(&msg, best_block, &self.keys_manager, &self.logger) {
                                                Ok(update) => update,
                                                Err(e) => try_chan_entry!(self, Err(e), chan),
                                        };
                                        match self.chain_monitor.watch_channel(chan.get().get_funding_txo().unwrap(), monitor) {
                                                ChannelMonitorUpdateStatus::Completed => {},
                                                e => {
                                                        let mut res = handle_monitor_update_res!(self, e, chan, RAACommitmentOrder::RevokeAndACKFirst, channel_ready.is_some(), OPTIONALLY_RESEND_FUNDING_LOCKED);
                                                        if let Err(MsgHandleErrInternal { ref mut shutdown_finish, .. }) = res {
                                                                // We weren't able to watch the channel to begin with, so no updates should be made on
                                                                // it. Previously, full_stack_target found an (unreachable) panic when the
                                                                // monitor update contained within `shutdown_finish` was applied.
                                                                if let Some((ref mut shutdown_finish, _)) = shutdown_finish {
                                                                        shutdown_finish.0.take();
                                                                }
                                                        }
                                                        return res
                                                },
                                        }
                                        if let Some(msg) = channel_ready {
                                                send_channel_ready!(self, channel_state.pending_msg_events, chan.get(), msg);
                                        }
                                        funding_tx
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                        }
                };
                log_info!(self.logger, "Broadcasting funding transaction with txid {}", funding_tx.txid());
                self.tx_broadcaster.broadcast_transaction(&funding_tx);
                Ok(())
        }

        fn internal_channel_ready(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReady) -> Result<(), MsgHandleErrInternal> {
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                match channel_state.by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }
                                let announcement_sigs_opt = try_chan_entry!(self, chan.get_mut().channel_ready(&msg, self.get_our_node_id(),
                                        self.genesis_hash.clone(), &self.best_block.read().unwrap(), &self.logger), chan);
                                if let Some(announcement_sigs) = announcement_sigs_opt {
                                        log_trace!(self.logger, "Sending announcement_signatures for channel {}", log_bytes!(chan.get().channel_id()));
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                node_id: counterparty_node_id.clone(),
                                                msg: announcement_sigs,
                                        });
                                } else if chan.get().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 {}", log_bytes!(chan.get().channel_id()));
                                        if let Ok(msg) = self.get_channel_update_for_unicast(chan.get()) {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendChannelUpdate {
                                                        node_id: counterparty_node_id.clone(),
                                                        msg,
                                                });
                                        }
                                }

                                emit_channel_ready_event!(self, chan.get_mut());

                                Ok(())
                        },
                        hash_map::Entry::Vacant(_) => Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
        }

        fn internal_shutdown(&self, counterparty_node_id: &PublicKey, their_features: &InitFeatures, msg: &msgs::Shutdown) -> Result<(), MsgHandleErrInternal> {
                let mut dropped_htlcs: Vec<(HTLCSource, PaymentHash)>;
                let result: Result<(), _> = loop {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;

                        match channel_state.by_id.entry(msg.channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_entry) => {
                                        if chan_entry.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }

                                        if !chan_entry.get().received_shutdown() {
                                                log_info!(self.logger, "Received a shutdown message from our counterparty for channel {}{}.",
                                                        log_bytes!(msg.channel_id),
                                                        if chan_entry.get().sent_shutdown() { " after we initiated shutdown" } else { "" });
                                        }

                                        let (shutdown, monitor_update, htlcs) = try_chan_entry!(self, chan_entry.get_mut().shutdown(&self.keys_manager, &their_features, &msg), chan_entry);
                                        dropped_htlcs = htlcs;

                                        // Update the monitor with the shutdown script if necessary.
                                        if let Some(monitor_update) = monitor_update {
                                                let update_res = self.chain_monitor.update_channel(chan_entry.get().get_funding_txo().unwrap(), monitor_update);
                                                let (result, is_permanent) =
                                                        handle_monitor_update_res!(self, update_res, chan_entry.get_mut(), RAACommitmentOrder::CommitmentFirst, chan_entry.key(), NO_UPDATE);
                                                if is_permanent {
                                                        remove_channel!(self, chan_entry);
                                                        break result;
                                                }
                                        }

                                        if let Some(msg) = shutdown {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                        node_id: *counterparty_node_id,
                                                        msg,
                                                });
                                        }

                                        break Ok(());
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), 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);
                }

                let _ = handle_error!(self, result, *counterparty_node_id);
                Ok(())
        }

        fn internal_closing_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::ClosingSigned) -> Result<(), MsgHandleErrInternal> {
                let (tx, chan_option) = {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        match channel_state.by_id.entry(msg.channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_entry) => {
                                        if chan_entry.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }
                                        let (closing_signed, tx) = try_chan_entry!(self, chan_entry.get_mut().closing_signed(&self.fee_estimator, &msg), chan_entry);
                                        if let Some(msg) = closing_signed {
                                                channel_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!(self, chan_entry)))
                                        } else { (tx, None) }
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                        }
                };
                if let Some(broadcast_tx) = tx {
                        log_info!(self.logger, "Broadcasting {}", log_tx!(broadcast_tx));
                        self.tx_broadcaster.broadcast_transaction(&broadcast_tx);
                }
                if let Some(chan) = chan_option {
                        if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                let mut channel_state = self.channel_state.lock().unwrap();
                                channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                        msg: update
                                });
                        }
                        self.issue_channel_close_events(&chan, ClosureReason::CooperativeClosure);
                }
                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.

                let pending_forward_info = self.decode_update_add_htlc_onion(msg);
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;

                match channel_state.by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }

                                let create_pending_htlc_status = |chan: &Channel<<K::Target as KeysInterface>::Signer>, 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_entry!(self, chan.get_mut().update_add_htlc(&msg, pending_forward_info, create_pending_htlc_status, &self.logger), chan);
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
                Ok(())
        }

        fn internal_update_fulfill_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) -> Result<(), MsgHandleErrInternal> {
                let mut channel_lock = self.channel_state.lock().unwrap();
                let (htlc_source, forwarded_htlc_value) = {
                        let channel_state = &mut *channel_lock;
                        match channel_state.by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
                                        if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }
                                        try_chan_entry!(self, chan.get_mut().update_fulfill_htlc(&msg), chan)
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                        }
                };
                self.claim_funds_internal(channel_lock, htlc_source, msg.payment_preimage.clone(), Some(forwarded_htlc_value), false, msg.channel_id);
                Ok(())
        }

        fn internal_update_fail_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) -> Result<(), MsgHandleErrInternal> {
                let mut channel_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_lock;
                match channel_state.by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }
                                try_chan_entry!(self, chan.get_mut().update_fail_htlc(&msg, HTLCFailReason::from_msg(msg)), chan);
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
                Ok(())
        }

        fn internal_update_fail_malformed_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) -> Result<(), MsgHandleErrInternal> {
                let mut channel_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_lock;
                match channel_state.by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }
                                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_entry!(self, Err(chan_err), chan);
                                }
                                try_chan_entry!(self, chan.get_mut().update_fail_malformed_htlc(&msg, HTLCFailReason::reason(msg.failure_code, msg.sha256_of_onion.to_vec())), chan);
                                Ok(())
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
        }

        fn internal_commitment_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::CommitmentSigned) -> Result<(), MsgHandleErrInternal> {
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                match channel_state.by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }
                                let (revoke_and_ack, commitment_signed, monitor_update) =
                                        match chan.get_mut().commitment_signed(&msg, &self.logger) {
                                                Err((None, e)) => try_chan_entry!(self, Err(e), chan),
                                                Err((Some(update), e)) => {
                                                        assert!(chan.get().is_awaiting_monitor_update());
                                                        let _ = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), update);
                                                        try_chan_entry!(self, Err(e), chan);
                                                        unreachable!();
                                                },
                                                Ok(res) => res
                                        };
                                let update_res = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update);
                                if let Err(e) = handle_monitor_update_res!(self, update_res, chan, RAACommitmentOrder::RevokeAndACKFirst, true, commitment_signed.is_some()) {
                                        return Err(e);
                                }

                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendRevokeAndACK {
                                        node_id: counterparty_node_id.clone(),
                                        msg: revoke_and_ack,
                                });
                                if let Some(msg) = commitment_signed {
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                node_id: counterparty_node_id.clone(),
                                                updates: msgs::CommitmentUpdate {
                                                        update_add_htlcs: Vec::new(),
                                                        update_fulfill_htlcs: Vec::new(),
                                                        update_fail_htlcs: Vec::new(),
                                                        update_fail_malformed_htlcs: Vec::new(),
                                                        update_fee: None,
                                                        commitment_signed: msg,
                                                },
                                        });
                                }
                                Ok(())
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), 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 forward_event = None;
                        let mut new_intercept_events = Vec::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.genesis_hash)
                                                        {
                                                                let intercept_id = InterceptId(Sha256::hash(&forward_info.incoming_shared_secret).into_inner());
                                                                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(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
                                                                                });
                                                                                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,
                                                                                        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 {
                                                                        forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS));
                                                                }
                                                                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);
                        }

                        match forward_event {
                                Some(time) => {
                                        let mut pending_events = self.pending_events.lock().unwrap();
                                        pending_events.push(events::Event::PendingHTLCsForwardable {
                                                time_forwardable: time
                                        });
                                }
                                None => {},
                        }
                }
        }

        fn internal_revoke_and_ack(&self, counterparty_node_id: &PublicKey, msg: &msgs::RevokeAndACK) -> Result<(), MsgHandleErrInternal> {
                let mut htlcs_to_fail = Vec::new();
                let res = loop {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        match channel_state.by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
                                        if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                                break Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }
                                        let was_paused_for_mon_update = chan.get().is_awaiting_monitor_update();
                                        let raa_updates = break_chan_entry!(self,
                                                chan.get_mut().revoke_and_ack(&msg, &self.logger), chan);
                                        htlcs_to_fail = raa_updates.holding_cell_failed_htlcs;
                                        let update_res = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), raa_updates.monitor_update);
                                        if was_paused_for_mon_update {
                                                assert!(update_res != ChannelMonitorUpdateStatus::Completed);
                                                assert!(raa_updates.commitment_update.is_none());
                                                assert!(raa_updates.accepted_htlcs.is_empty());
                                                assert!(raa_updates.failed_htlcs.is_empty());
                                                assert!(raa_updates.finalized_claimed_htlcs.is_empty());
                                                break Err(MsgHandleErrInternal::ignore_no_close("Existing pending monitor update prevented responses to RAA".to_owned()));
                                        }
                                        if update_res != ChannelMonitorUpdateStatus::Completed {
                                                if let Err(e) = handle_monitor_update_res!(self, update_res, chan,
                                                                RAACommitmentOrder::CommitmentFirst, false,
                                                                raa_updates.commitment_update.is_some(), false,
                                                                raa_updates.accepted_htlcs, raa_updates.failed_htlcs,
                                                                raa_updates.finalized_claimed_htlcs) {
                                                        break Err(e);
                                                } else { unreachable!(); }
                                        }
                                        if let Some(updates) = raa_updates.commitment_update {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                        node_id: counterparty_node_id.clone(),
                                                        updates,
                                                });
                                        }
                                        break Ok((raa_updates.accepted_htlcs, raa_updates.failed_htlcs,
                                                        raa_updates.finalized_claimed_htlcs,
                                                        chan.get().get_short_channel_id()
                                                                .unwrap_or(chan.get().outbound_scid_alias()),
                                                        chan.get().get_funding_txo().unwrap(),
                                                        chan.get().get_user_id()))
                                },
                                hash_map::Entry::Vacant(_) => break Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                        }
                };
                self.fail_holding_cell_htlcs(htlcs_to_fail, msg.channel_id, counterparty_node_id);
                match res {
                        Ok((pending_forwards, mut pending_failures, finalized_claim_htlcs,
                                short_channel_id, channel_outpoint, user_channel_id)) =>
                        {
                                for failure in pending_failures.drain(..) {
                                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(*counterparty_node_id), channel_id: channel_outpoint.to_channel_id() };
                                        self.fail_htlc_backwards_internal(&failure.0, &failure.1, &failure.2, receiver);
                                }
                                self.forward_htlcs(&mut [(short_channel_id, channel_outpoint, user_channel_id, pending_forwards)]);
                                self.finalize_claims(finalized_claim_htlcs);
                                Ok(())
                        },
                        Err(e) => Err(e)
                }
        }

        fn internal_update_fee(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFee) -> Result<(), MsgHandleErrInternal> {
                let mut channel_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_lock;
                match channel_state.by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }
                                try_chan_entry!(self, chan.get_mut().update_fee(&self.fee_estimator, &msg, &self.logger), chan);
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
                Ok(())
        }

        fn internal_announcement_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) -> Result<(), MsgHandleErrInternal> {
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;

                match channel_state.by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }
                                if !chan.get().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}));
                                }

                                channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelAnnouncement {
                                        msg: try_chan_entry!(self, chan.get_mut().announcement_signatures(
                                                self.get_our_node_id(), self.genesis_hash.clone(), self.best_block.read().unwrap().height(), msg), chan),
                                        // 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: self.get_channel_update_for_broadcast(chan.get()).unwrap(),
                                });
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
                Ok(())
        }

        /// Returns ShouldPersist if anything changed, otherwise either SkipPersist or an Err.
        fn internal_channel_update(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelUpdate) -> Result<NotifyOption, MsgHandleErrInternal> {
                let chan_id = match self.short_to_chan_info.read().unwrap().get(&msg.contents.short_channel_id) {
                        Some((_cp_id, chan_id)) => chan_id.clone(),
                        None => {
                                // It's not a local channel
                                return Ok(NotifyOption::SkipPersist)
                        }
                };
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                match channel_state.by_id.entry(chan_id) {
                        hash_map::Entry::Occupied(mut chan) => {
                                if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                        if chan.get().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::SkipPersist);
                                        }
                                        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.get().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::SkipPersist);
                                } else {
                                        log_debug!(self.logger, "Received channel_update for channel {}.", log_bytes!(chan_id));
                                        try_chan_entry!(self, chan.get_mut().channel_update(&msg), chan);
                                }
                        },
                        hash_map::Entry::Vacant(_) => return Ok(NotifyOption::SkipPersist)
                }
                Ok(NotifyOption::DoPersist)
        }

        fn internal_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) -> Result<(), MsgHandleErrInternal> {
                let htlc_forwards;
                let need_lnd_workaround = {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;

                        match channel_state.by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
                                        if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }
                                        // 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_entry!(self, chan.get_mut().channel_reestablish(
                                                msg, &self.logger, self.our_network_pubkey.clone(), self.genesis_hash,
                                                &*self.best_block.read().unwrap()), chan);
                                        let mut channel_update = None;
                                        if let Some(msg) = responses.shutdown_msg {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                        node_id: counterparty_node_id.clone(),
                                                        msg,
                                                });
                                        } else if chan.get().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.get()) {
                                                        channel_update = Some(events::MessageSendEvent::SendChannelUpdate {
                                                                node_id: chan.get().get_counterparty_node_id(),
                                                                msg,
                                                        });
                                                }
                                        }
                                        let need_lnd_workaround = chan.get_mut().workaround_lnd_bug_4006.take();
                                        htlc_forwards = self.handle_channel_resumption(
                                                &mut channel_state.pending_msg_events, chan.get_mut(), responses.raa, responses.commitment_update, responses.order,
                                                Vec::new(), None, responses.channel_ready, responses.announcement_sigs);
                                        if let Some(upd) = channel_update {
                                                channel_state.pending_msg_events.push(upd);
                                        }
                                        need_lnd_workaround
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                        }
                };

                if let Some(forwards) = htlc_forwards {
                        self.forward_htlcs(&mut [forwards][..]);
                }

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

        /// Process pending events from the `chain::Watch`, returning whether any events were processed.
        fn process_pending_monitor_events(&self) -> bool {
                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", log_bytes!(preimage.0));
                                                        self.claim_funds_internal(self.channel_state.lock().unwrap(), htlc_update.source, preimage, htlc_update.htlc_value_satoshis.map(|v| v * 1000), true, funding_outpoint.to_channel_id());
                                                } else {
                                                        log_trace!(self.logger, "Failing HTLC with hash {} from our monitor", log_bytes!(htlc_update.payment_hash.0));
                                                        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::CommitmentTxConfirmed(funding_outpoint) |
                                        MonitorEvent::UpdateFailed(funding_outpoint) => {
                                                let mut channel_lock = self.channel_state.lock().unwrap();
                                                let channel_state = &mut *channel_lock;
                                                let by_id = &mut channel_state.by_id;
                                                let pending_msg_events = &mut channel_state.pending_msg_events;
                                                if let hash_map::Entry::Occupied(chan_entry) = by_id.entry(funding_outpoint.to_channel_id()) {
                                                        let mut chan = remove_channel!(self, chan_entry);
                                                        failed_channels.push(chan.force_shutdown(false));
                                                        if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                                                pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                        msg: update
                                                                });
                                                        }
                                                        let reason = if let MonitorEvent::UpdateFailed(_) = monitor_event {
                                                                ClosureReason::ProcessingError { err: "Failed to persist ChannelMonitor update during chain sync".to_string() }
                                                        } else {
                                                                ClosureReason::CommitmentTxConfirmed
                                                        };
                                                        self.issue_channel_close_events(&chan, reason);
                                                        pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                                node_id: chan.get_counterparty_node_id(),
                                                                action: msgs::ErrorAction::SendErrorMessage {
                                                                        msg: msgs::ErrorMessage { channel_id: chan.channel_id(), data: "Channel force-closed".to_owned() }
                                                                },
                                                        });
                                                }
                                        },
                                        MonitorEvent::Completed { funding_txo, monitor_update_id } => {
                                                self.channel_monitor_updated(&funding_txo, monitor_update_id);
                                        },
                                }
                        }
                }

                for failure in failed_channels.drain(..) {
                        self.finish_force_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) {
                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();
                let mut handle_errors = Vec::new();
                {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        let by_id = &mut channel_state.by_id;
                        let pending_msg_events = &mut channel_state.pending_msg_events;

                        by_id.retain(|channel_id, chan| {
                                match chan.maybe_free_holding_cell_htlcs(&self.logger) {
                                        Ok((commitment_opt, holding_cell_failed_htlcs)) => {
                                                if !holding_cell_failed_htlcs.is_empty() {
                                                        failed_htlcs.push((
                                                                holding_cell_failed_htlcs,
                                                                *channel_id,
                                                                chan.get_counterparty_node_id()
                                                        ));
                                                }
                                                if let Some((commitment_update, monitor_update)) = commitment_opt {
                                                        match self.chain_monitor.update_channel(chan.get_funding_txo().unwrap(), monitor_update) {
                                                                ChannelMonitorUpdateStatus::Completed => {
                                                                        pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                                                node_id: chan.get_counterparty_node_id(),
                                                                                updates: commitment_update,
                                                                        });
                                                                },
                                                                e => {
                                                                        has_monitor_update = true;
                                                                        let (res, close_channel) = handle_monitor_update_res!(self, e, chan, RAACommitmentOrder::CommitmentFirst, channel_id, COMMITMENT_UPDATE_ONLY);
                                                                        handle_errors.push((chan.get_counterparty_node_id(), res));
                                                                        if close_channel { return false; }
                                                                },
                                                        }
                                                }
                                                true
                                        },
                                        Err(e) => {
                                                let (close_channel, res) = convert_chan_err!(self, e, chan, channel_id);
                                                handle_errors.push((chan.get_counterparty_node_id(), Err(res)));
                                                // ChannelClosed event is generated by handle_error for us
                                                !close_channel
                                        }
                                }
                        });
                }

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

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

                has_update
        }

        /// 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 channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        let by_id = &mut channel_state.by_id;
                        let pending_msg_events = &mut channel_state.pending_msg_events;

                        by_id.retain(|channel_id, chan| {
                                match chan.maybe_propose_closing_signed(&self.fee_estimator, &self.logger) {
                                        Ok((msg_opt, tx_opt)) => {
                                                if let Some(msg) = msg_opt {
                                                        has_update = true;
                                                        pending_msg_events.push(events::MessageSendEvent::SendClosingSigned {
                                                                node_id: chan.get_counterparty_node_id(), msg,
                                                        });
                                                }
                                                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, ClosureReason::CooperativeClosure);

                                                        log_info!(self.logger, "Broadcasting {}", log_tx!(tx));
                                                        self.tx_broadcaster.broadcast_transaction(&tx);
                                                        update_maps_on_chan_removal!(self, chan);
                                                        false
                                                } else { true }
                                        },
                                        Err(e) => {
                                                has_update = true;
                                                let (close_channel, res) = convert_chan_err!(self, e, chan, channel_id);
                                                handle_errors.push((chan.get_counterparty_node_id(), Err(res)));
                                                !close_channel
                                        }
                                }
                        });
                }

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

                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((funding_txo, update)) = failure.0.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::ClosingMonitorUpdate((funding_txo, update)));
                        }
                        self.finish_force_close_channel(failure);
                }
        }

        fn set_payment_hash_secret_map(&self, payment_hash: PaymentHash, payment_preimage: Option<PaymentPreimage>, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32) -> Result<PaymentSecret, APIError> {
                assert!(invoice_expiry_delta_secs <= 60*60*24*365); // Sadly bitcoin timestamps are u32s, so panic before 2106

                if min_value_msat.is_some() && min_value_msat.unwrap() > MAX_VALUE_MSAT {
                        return Err(APIError::APIMisuseError { err: format!("min_value_msat of {} greater than total 21 million bitcoin supply", min_value_msat.unwrap()) });
                }

                let payment_secret = PaymentSecret(self.keys_manager.get_secure_random_bytes());

                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let mut payment_secrets = self.pending_inbound_payments.lock().unwrap();
                match payment_secrets.entry(payment_hash) {
                        hash_map::Entry::Vacant(e) => {
                                e.insert(PendingInboundPayment {
                                        payment_secret, min_value_msat, payment_preimage,
                                        user_payment_id: 0, // For compatibility with version 0.0.103 and earlier
                                        // We assume that highest_seen_timestamp is pretty close to the current time -
                                        // it's updated when we receive a new block with the maximum time we've seen in
                                        // a header. It should never be more than two hours in the future.
                                        // Thus, we add two hours here as a buffer to ensure we absolutely
                                        // never fail a payment too early.
                                        // Note that we assume that received blocks have reasonably up-to-date
                                        // timestamps.
                                        expiry_time: self.highest_seen_timestamp.load(Ordering::Acquire) as u64 + invoice_expiry_delta_secs as u64 + 7200,
                                });
                        },
                        hash_map::Entry::Occupied(_) => return Err(APIError::APIMisuseError { err: "Duplicate payment hash".to_owned() }),
                }
                Ok(payment_secret)
        }

        /// 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::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.
        ///
        /// [`claim_funds`]: Self::claim_funds
        /// [`PaymentClaimable`]: events::Event::PaymentClaimable
        /// [`PaymentClaimable::payment_preimage`]: events::Event::PaymentClaimable::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) -> Result<(PaymentHash, PaymentSecret), ()> {
                inbound_payment::create(&self.inbound_payment_key, min_value_msat, invoice_expiry_delta_secs, &self.keys_manager, self.highest_seen_timestamp.load(Ordering::Acquire) as u64)
        }

        /// Legacy version of [`create_inbound_payment`]. Use this method if you wish to share
        /// serialized state with LDK node(s) running 0.0.103 and earlier.
        ///
        /// May panic if `invoice_expiry_delta_secs` is greater than one year.
        ///
        /// # Note
        /// This method is deprecated and will be removed soon.
        ///
        /// [`create_inbound_payment`]: Self::create_inbound_payment
        #[deprecated]
        pub fn create_inbound_payment_legacy(&self, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32) -> Result<(PaymentHash, PaymentSecret), APIError> {
                let payment_preimage = PaymentPreimage(self.keys_manager.get_secure_random_bytes());
                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
                let payment_secret = self.set_payment_hash_secret_map(payment_hash, Some(payment_preimage), min_value_msat, invoice_expiry_delta_secs)?;
                Ok((payment_hash, payment_secret))
        }

        /// 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`
        /// set to at least [`MIN_FINAL_CLTV_EXPIRY`].
        ///
        /// 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.
        ///
        /// [`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) -> 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)
        }

        /// Legacy version of [`create_inbound_payment_for_hash`]. Use this method if you wish to share
        /// serialized state with LDK node(s) running 0.0.103 and earlier.
        ///
        /// May panic if `invoice_expiry_delta_secs` is greater than one year.
        ///
        /// # Note
        /// This method is deprecated and will be removed soon.
        ///
        /// [`create_inbound_payment_for_hash`]: Self::create_inbound_payment_for_hash
        #[deprecated]
        pub fn create_inbound_payment_for_hash_legacy(&self, payment_hash: PaymentHash, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32) -> Result<PaymentSecret, APIError> {
                self.set_payment_hash_secret_map(payment_hash, None, min_value_msat, invoice_expiry_delta_secs)
        }

        /// 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)
        }

        /// 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::chain::keysinterface::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.genesis_hash, &self.fake_scid_rand_bytes, &self.keys_manager);
                        // 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::chain::keysinterface::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.genesis_hash, &self.fake_scid_rand_bytes, &self.keys_manager);
                        // 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();

                for chan in self.channel_state.lock().unwrap().by_id.values() {
                        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, fuzzing, 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(test)]
        pub fn pop_pending_event(&self) -> Option<events::Event> {
                let mut events = self.pending_events.lock().unwrap();
                if events.is_empty() { None } else { Some(events.remove(0)) }
        }

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

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

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

                let mut result = NotifyOption::SkipPersist;

                // 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 = mem::replace(&mut *self.pending_events.lock().unwrap(), vec![]);
                if !pending_events.is_empty() {
                        result = NotifyOption::DoPersist;
                }

                for event in pending_events {
                        handler(event).await;
                }

                if result == NotifyOption::DoPersist {
                        self.persistence_notifier.notify();
                }
        }
}

impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> MessageSendEventsProvider for ChannelManager<M, T, K, F, L>
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
                                L::Target: Logger,
{
        fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
                let events = RefCell::new(Vec::new());
                PersistenceNotifierGuard::optionally_notify(&self.total_consistency_lock, &self.persistence_notifier, || {
                        let mut result = NotifyOption::SkipPersist;

                        // 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 mut channel_state = self.channel_state.lock().unwrap();
                        mem::swap(&mut pending_events, &mut channel_state.pending_msg_events);

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

                        result
                });
                events.into_inner()
        }
}

impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> EventsProvider for ChannelManager<M, T, K, F, L>
where
        M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        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 {
                PersistenceNotifierGuard::optionally_notify(&self.total_consistency_lock, &self.persistence_notifier, || {
                        let mut result = NotifyOption::SkipPersist;

                        // 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 = mem::replace(&mut *self.pending_events.lock().unwrap(), vec![]);
                        if !pending_events.is_empty() {
                                result = NotifyOption::DoPersist;
                        }

                        for event in pending_events {
                                handler.handle_event(event);
                        }

                        result
                });
        }
}

impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> chain::Listen for ChannelManager<M, T, K, F, L>
where
        M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn filtered_block_connected(&self, header: &BlockHeader, 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: &BlockHeader, height: u32) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                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.genesis_hash.clone(), self.get_our_node_id(), &self.logger));
        }
}

impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> chain::Confirm for ChannelManager<M, T, K, F, L>
where
        M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn transactions_confirmed(&self, header: &BlockHeader, 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::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                self.do_chain_event(Some(height), |channel| channel.transactions_confirmed(&block_hash, height, txdata, self.genesis_hash.clone(), self.get_our_node_id(), &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.genesis_hash.clone(), self.get_our_node_id(), &self.logger));
                }
        }

        fn best_block_updated(&self, header: &BlockHeader, 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::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                *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.genesis_hash.clone(), self.get_our_node_id(), &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, Option<BlockHash>)> {
                let channel_state = self.channel_state.lock().unwrap();
                let mut res = Vec::with_capacity(channel_state.by_id.len());
                for chan in channel_state.by_id.values() {
                        if let (Some(funding_txo), block_hash) = (chan.get_funding_txo(), chan.get_funding_tx_confirmed_in()) {
                                res.push((funding_txo.txid, block_hash));
                        }
                }
                res
        }

        fn transaction_unconfirmed(&self, txid: &Txid) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                self.do_chain_event(None, |channel| {
                        if let Some(funding_txo) = channel.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, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F, L>
where
        M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        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<<K::Target as KeysInterface>::Signer>) -> 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 mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        let pending_msg_events = &mut channel_state.pending_msg_events;
                        channel_state.by_id.retain(|_, 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.get_counterparty_node_id()), channel_id: channel.channel_id() }));
                                        }
                                        if let Some(channel_ready) = channel_ready_opt {
                                                send_channel_ready!(self, pending_msg_events, channel, channel_ready);
                                                if channel.is_usable() {
                                                        log_trace!(self.logger, "Sending channel_ready with private initial channel_update for our counterparty on channel {}", log_bytes!(channel.channel_id()));
                                                        if let Ok(msg) = self.get_channel_update_for_unicast(channel) {
                                                                pending_msg_events.push(events::MessageSendEvent::SendChannelUpdate {
                                                                        node_id: channel.get_counterparty_node_id(),
                                                                        msg,
                                                                });
                                                        }
                                                } else {
                                                        log_trace!(self.logger, "Sending channel_ready WITHOUT channel_update for {}", log_bytes!(channel.channel_id()));
                                                }
                                        }

                                        emit_channel_ready_event!(self, channel);

                                        if let Some(announcement_sigs) = announcement_sigs {
                                                log_trace!(self.logger, "Sending announcement_signatures for channel {}", log_bytes!(channel.channel_id()));
                                                pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                        node_id: channel.get_counterparty_node_id(),
                                                        msg: announcement_sigs,
                                                });
                                                if let Some(height) = height_opt {
                                                        if let Some(announcement) = channel.get_signed_channel_announcement(self.get_our_node_id(), self.genesis_hash, height) {
                                                                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: self.get_channel_update_for_broadcast(channel).unwrap(),
                                                                });
                                                        }
                                                }
                                        }
                                        if channel.is_our_channel_ready() {
                                                if let Some(real_scid) = channel.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.get_counterparty_node_id(), channel.channel_id()));
                                                        assert!(scid_insert.is_none() || scid_insert.unwrap() == (channel.get_counterparty_node_id(), channel.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);
                                        // 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.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, reason);
                                        pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                node_id: channel.get_counterparty_node_id(),
                                                action: msgs::ErrorAction::SendErrorMessage { msg: msgs::ErrorMessage {
                                                        channel_id: channel.channel_id(),
                                                        data: reason_message,
                                                } },
                                        });
                                        return false;
                                }
                                true
                        });
                }

                if let Some(height) = height_opt {
                        self.claimable_payments.lock().unwrap().claimable_htlcs.retain(|payment_hash, (_, htlcs)| {
                                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 }
                                });
                                !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,
                                                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);
                }
        }

        /// Blocks until ChannelManager needs to be persisted or a timeout is reached. It returns a bool
        /// indicating whether persistence is necessary. Only one listener on
        /// [`await_persistable_update`], [`await_persistable_update_timeout`], or a future returned by
        /// [`get_persistable_update_future`] is guaranteed to be woken up.
        ///
        /// Note that this method is not available with the `no-std` feature.
        ///
        /// [`await_persistable_update`]: Self::await_persistable_update
        /// [`await_persistable_update_timeout`]: Self::await_persistable_update_timeout
        /// [`get_persistable_update_future`]: Self::get_persistable_update_future
        #[cfg(any(test, feature = "std"))]
        pub fn await_persistable_update_timeout(&self, max_wait: Duration) -> bool {
                self.persistence_notifier.wait_timeout(max_wait)
        }

        /// Blocks until ChannelManager needs to be persisted. Only one listener on
        /// [`await_persistable_update`], `await_persistable_update_timeout`, or a future returned by
        /// [`get_persistable_update_future`] is guaranteed to be woken up.
        ///
        /// [`await_persistable_update`]: Self::await_persistable_update
        /// [`get_persistable_update_future`]: Self::get_persistable_update_future
        pub fn await_persistable_update(&self) {
                self.persistence_notifier.wait()
        }

        /// Gets a [`Future`] that completes when a persistable update is available. 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_persistable_update_future(&self) -> Future {
                self.persistence_notifier.get_future()
        }

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

impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref >
        ChannelMessageHandler for ChannelManager<M, T, K, F, L>
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn handle_open_channel(&self, counterparty_node_id: &PublicKey, their_features: InitFeatures, msg: &msgs::OpenChannel) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_open_channel(counterparty_node_id, their_features, msg), *counterparty_node_id);
        }

        fn handle_accept_channel(&self, counterparty_node_id: &PublicKey, their_features: InitFeatures, msg: &msgs::AcceptChannel) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_accept_channel(counterparty_node_id, their_features, msg), *counterparty_node_id);
        }

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

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

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

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

        fn handle_update_fail_malformed_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_update_fail_malformed_htlc(counterparty_node_id, msg), *counterparty_node_id);
        }

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

        fn handle_announcement_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                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.total_consistency_lock, &self.persistence_notifier, || {
                        if let Ok(persist) = handle_error!(self, self.internal_channel_update(counterparty_node_id, msg), *counterparty_node_id) {
                                persist
                        } else {
                                NotifyOption::SkipPersist
                        }
                });
        }

        fn handle_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_channel_reestablish(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn peer_disconnected(&self, counterparty_node_id: &PublicKey, no_connection_possible: bool) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let mut failed_channels = Vec::new();
                let mut no_channels_remain = true;
                {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
                        let pending_msg_events = &mut channel_state.pending_msg_events;
                        log_debug!(self.logger, "Marking channels with {} disconnected and generating channel_updates. We believe we {} make future connections to this peer.",
                                log_pubkey!(counterparty_node_id), if no_connection_possible { "cannot" } else { "can" });
                        channel_state.by_id.retain(|_, chan| {
                                if chan.get_counterparty_node_id() == *counterparty_node_id {
                                        chan.remove_uncommitted_htlcs_and_mark_paused(&self.logger);
                                        if chan.is_shutdown() {
                                                update_maps_on_chan_removal!(self, chan);
                                                self.issue_channel_close_events(chan, ClosureReason::DisconnectedPeer);
                                                return false;
                                        } else {
                                                no_channels_remain = false;
                                        }
                                }
                                true
                        });
                        pending_msg_events.retain(|msg| {
                                match msg {
                                        &events::MessageSendEvent::SendAcceptChannel { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendOpenChannel { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendFundingCreated { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendFundingSigned { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendChannelReady { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendAnnouncementSignatures { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::UpdateHTLCs { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendRevokeAndACK { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendClosingSigned { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendShutdown { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendChannelReestablish { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendChannelAnnouncement { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::BroadcastChannelAnnouncement { .. } => true,
                                        &events::MessageSendEvent::BroadcastChannelUpdate { .. } => true,
                                        &events::MessageSendEvent::SendChannelUpdate { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::HandleError { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::SendChannelRangeQuery { .. } => false,
                                        &events::MessageSendEvent::SendShortIdsQuery { .. } => false,
                                        &events::MessageSendEvent::SendReplyChannelRange { .. } => false,
                                        &events::MessageSendEvent::SendGossipTimestampFilter { .. } => false,
                                }
                        });
                }
                if no_channels_remain {
                        self.per_peer_state.write().unwrap().remove(counterparty_node_id);
                }

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

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

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

                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);

                {
                        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) => {
                                        e.insert(Mutex::new(PeerState {
                                                latest_features: init_msg.features.clone(),
                                        }));
                                },
                                hash_map::Entry::Occupied(e) => {
                                        e.get().lock().unwrap().latest_features = init_msg.features.clone();
                                },
                        }
                }

                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                let pending_msg_events = &mut channel_state.pending_msg_events;
                channel_state.by_id.retain(|_, chan| {
                        let retain = if chan.get_counterparty_node_id() == *counterparty_node_id {
                                if !chan.have_received_message() {
                                        // If we created this (outbound) channel while we were disconnected from the
                                        // peer we probably failed to send the open_channel message, which is now
                                        // lost. We can't have had anything pending related to this channel, so we just
                                        // drop it.
                                        false
                                } else {
                                        pending_msg_events.push(events::MessageSendEvent::SendChannelReestablish {
                                                node_id: chan.get_counterparty_node_id(),
                                                msg: chan.get_channel_reestablish(&self.logger),
                                        });
                                        true
                                }
                        } else { true };
                        if retain && chan.get_counterparty_node_id() != *counterparty_node_id {
                                if let Some(msg) = chan.get_signed_channel_announcement(self.get_our_node_id(), self.genesis_hash.clone(), self.best_block.read().unwrap().height()) {
                                        if let Ok(update_msg) = self.get_channel_update_for_broadcast(chan) {
                                                pending_msg_events.push(events::MessageSendEvent::SendChannelAnnouncement {
                                                        node_id: *counterparty_node_id,
                                                        msg, update_msg,
                                                });
                                        }
                                }
                        }
                        retain
                });
                //TODO: Also re-broadcast announcement_signatures
                Ok(())
        }

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

                if msg.channel_id == [0; 32] {
                        for chan in self.list_channels() {
                                if chan.counterparty.node_id == *counterparty_node_id {
                                        // Untrusted messages from peer, we throw away the error if id points to a non-existent channel
                                        let _ = self.force_close_channel_with_peer(&chan.channel_id, counterparty_node_id, Some(&msg.data), true);
                                }
                        }
                } else {
                        {
                                // First check if we can advance the channel type and try again.
                                let mut channel_state = self.channel_state.lock().unwrap();
                                if let Some(chan) = channel_state.by_id.get_mut(&msg.channel_id) {
                                        if chan.get_counterparty_node_id() != *counterparty_node_id {
                                                return;
                                        }
                                        if let Ok(msg) = chan.maybe_handle_error_without_close(self.genesis_hash) {
                                                channel_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()
        }

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

/// Fetches the set of [`NodeFeatures`] flags which are provided by or required by
/// [`ChannelManager`].
pub fn provided_node_features() -> NodeFeatures {
        provided_init_features().to_context()
}

/// Fetches the set of [`InvoiceFeatures`] flags which 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 provided_invoice_features() -> InvoiceFeatures {
        provided_init_features().to_context()
}

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

/// Fetches the set of [`InitFeatures`] flags which are provided by or required by
/// [`ChannelManager`].
pub fn provided_init_features() -> 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_optional();
        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();
        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),
                        // 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, self.next_outbound_htlc_limit_msat, (default_value, outbound_capacity_msat.0.unwrap() as u64)),
                        (20, self.inbound_capacity_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),
                });
                Ok(())
        }
}

impl Readable for ChannelDetails {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
                init_and_read_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),
                        (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),
                });

                // `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(),
                        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,
                })
        }
}

impl_writeable_tlv_based!(PhantomRouteHints, {
        (2, channels, vec_type),
        (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),
        },
        (2, ReceiveKeysend) => {
                (0, payment_preimage, required),
                (2, incoming_cltv_expiry, required),
        },
;);

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),
});


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)
});

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),
                        (4, payment_data, option),
                        (6, self.cltv_expiry, required),
                        (8, keysend_preimage, option),
                });
                Ok(())
        }
}

impl Readable for ClaimableHTLC {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
                let mut prev_hop = crate::util::ser::OptionDeserWrapper(None);
                let mut value = 0;
                let mut payment_data: Option<msgs::FinalOnionHopData> = None;
                let mut cltv_expiry = 0;
                let mut total_msat = None;
                let mut keysend_preimage: Option<PaymentPreimage> = None;
                read_tlv_fields!(reader, {
                        (0, prev_hop, required),
                        (1, total_msat, option),
                        (2, value, required),
                        (4, payment_data, option),
                        (6, cltv_expiry, required),
                        (8, keysend_preimage, option)
                });
                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,
                        total_msat: total_msat.unwrap(),
                        onion_payload,
                        cltv_expiry,
                })
        }
}

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::OptionDeserWrapper<SecretKey> = crate::util::ser::OptionDeserWrapper(None);
                                let mut first_hop_htlc_msat: u64 = 0;
                                let mut path = Some(Vec::new());
                                let mut payment_id = None;
                                let mut payment_secret = None;
                                let mut payment_params = None;
                                read_tlv_fields!(reader, {
                                        (0, session_priv, required),
                                        (1, payment_id, option),
                                        (2, first_hop_htlc_msat, required),
                                        (3, payment_secret, option),
                                        (4, path, vec_type),
                                        (5, payment_params, 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()));
                                }
                                Ok(HTLCSource::OutboundRoute {
                                        session_priv: session_priv.0.unwrap(),
                                        first_hop_htlc_msat,
                                        path: path.unwrap(),
                                        payment_id: payment_id.unwrap(),
                                        payment_secret,
                                        payment_params,
                                })
                        }
                        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, payment_secret, payment_params } => {
                                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, payment_secret, option),
                                        (4, *path, vec_type),
                                        (5, payment_params, 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, K: Deref, F: Deref, L: Deref> Writeable for ChannelManager<M, T, K, F, L>
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        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.genesis_hash.write(writer)?;
                {
                        let best_block = self.best_block.read().unwrap();
                        best_block.height().write(writer)?;
                        best_block.block_hash().write(writer)?;
                }

                {
                        // Take `channel_state` lock temporarily to avoid creating a lock order that requires
                        // that the `forward_htlcs` lock is taken after `channel_state`
                        let channel_state = self.channel_state.lock().unwrap();
                        let mut unfunded_channels = 0;
                        for (_, channel) in channel_state.by_id.iter() {
                                if !channel.is_funding_initiated() {
                                        unfunded_channels += 1;
                                }
                        }
                        ((channel_state.by_id.len() - unfunded_channels) as u64).write(writer)?;
                        for (_, channel) in channel_state.by_id.iter() {
                                if channel.is_funding_initiated() {
                                        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 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.lock().unwrap();

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

                let per_peer_state = self.per_peer_state.write().unwrap();
                (per_peer_state.len() as u64).write(writer)?;
                for (peer_pubkey, peer_state_mutex) in per_peer_state.iter() {
                        peer_pubkey.write(writer)?;
                        let peer_state = peer_state_mutex.lock().unwrap();
                        peer_state.latest_features.write(writer)?;
                }

                let events = self.pending_events.lock().unwrap();
                (events.len() as u64).write(writer)?;
                for event in events.iter() {
                        event.write(writer)?;
                }

                let background_events = self.pending_background_events.lock().unwrap();
                (background_events.len() as u64).write(writer)?;
                for event in background_events.iter() {
                        match event {
                                BackgroundEvent::ClosingMonitorUpdate((funding_txo, monitor_update)) => {
                                        0u8.write(writer)?;
                                        funding_txo.write(writer)?;
                                        monitor_update.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::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;
                } else {
                        debug_assert!(false, "While we have code to serialize pending_claiming_payments, the map should always be empty until a later PR");
                }

                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),
                        (7, self.fake_scid_rand_bytes, required),
                        (9, htlc_purposes, vec_type),
                        (11, self.probing_cookie_secret, required),
                });

                Ok(())
        }
}

/// 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, K: Deref, F: Deref, L: Deref>
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        /// 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 keys_manager: K,

        /// 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 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.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.
        ///
        /// (C-not exported) because we have no HashMap bindings
        pub channel_monitors: HashMap<OutPoint, &'a mut ChannelMonitor<<K::Target as KeysInterface>::Signer>>,
}

impl<'a, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                ChannelManagerReadArgs<'a, M, T, K, F, L>
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
                T::Target: BroadcasterInterface,
                K::Target: KeysInterface,
                F::Target: FeeEstimator,
                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(keys_manager: K, fee_estimator: F, chain_monitor: M, tx_broadcaster: T, logger: L, default_config: UserConfig,
                        mut channel_monitors: Vec<&'a mut ChannelMonitor<<K::Target as KeysInterface>::Signer>>) -> Self {
                Self {
                        keys_manager, fee_estimator, chain_monitor, tx_broadcaster, 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, K: Deref, F: Deref, L: Deref>
        ReadableArgs<ChannelManagerReadArgs<'a, M, T, K, F, L>> for (BlockHash, Arc<ChannelManager<M, T, K, F, L>>)
        where M::Target: chain::Watch<<K::Target as KeysInterface>::Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn read<R: io::Read>(reader: &mut R, args: ChannelManagerReadArgs<'a, M, T, K, F, L>) -> Result<Self, DecodeError> {
                let (blockhash, chan_manager) = <(BlockHash, ChannelManager<M, T, K, F, L>)>::read(reader, args)?;
                Ok((blockhash, Arc::new(chan_manager)))
        }
}

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

                let genesis_hash: BlockHash = 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 by_id = 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 = Vec::new();
                for _ in 0..channel_count {
                        let mut channel: Channel<<K::Target as KeysInterface>::Signer> = Channel::read(reader, (&args.keys_manager, best_block_height))?;
                        let funding_txo = channel.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.get_latest_monitor_update_id() > monitor.get_latest_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 {} but the ChannelManager is at update_id {}.",
                                                log_bytes!(channel.channel_id()), monitor.get_latest_update_id(), channel.get_latest_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 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.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.");
                                        log_error!(args.logger, " The ChannelMonitor for channel {} is at update_id {} but the ChannelManager is at update_id {}.",
                                                log_bytes!(channel.channel_id()), monitor.get_latest_update_id(), channel.get_latest_monitor_update_id());
                                        let (_, mut new_failed_htlcs) = channel.force_shutdown(true);
                                        failed_htlcs.append(&mut new_failed_htlcs);
                                        monitor.broadcast_latest_holder_commitment_txn(&args.tx_broadcaster, &args.logger);
                                        channel_closures.push(events::Event::ChannelClosed {
                                                channel_id: channel.channel_id(),
                                                user_channel_id: channel.get_user_id(),
                                                reason: ClosureReason::OutdatedChannelManager
                                        });
                                        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",
                                                                log_bytes!(channel.channel_id()), log_bytes!(payment_hash.0));
                                                        failed_htlcs.push((channel_htlc_source.clone(), *payment_hash, channel.get_counterparty_node_id(), channel.channel_id()));
                                                }
                                        }
                                } else {
                                        log_info!(args.logger, "Successfully loaded channel {}", log_bytes!(channel.channel_id()));
                                        if let Some(short_channel_id) = channel.get_short_channel_id() {
                                                short_to_chan_info.insert(short_channel_id, (channel.get_counterparty_node_id(), channel.channel_id()));
                                        }
                                        if channel.is_funding_initiated() {
                                                id_to_peer.insert(channel.channel_id(), channel.get_counterparty_node_id());
                                        }
                                        by_id.insert(channel.channel_id(), channel);
                                }
                        } 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.force_shutdown(false);
                                channel_closures.push(events::Event::ChannelClosed {
                                        channel_id: channel.channel_id(),
                                        user_channel_id: channel.get_user_id(),
                                        reason: ClosureReason::DisconnectedPeer,
                                });
                        } else {
                                log_error!(args.logger, "Missing ChannelMonitor for channel {} needed by ChannelManager.", log_bytes!(channel.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 (ref funding_txo, ref mut monitor) in args.channel_monitors.iter_mut() {
                        if !funding_txo_set.contains(funding_txo) {
                                log_info!(args.logger, "Broadcasting latest holder commitment transaction for closed channel {}", log_bytes!(funding_txo.to_channel_id()));
                                monitor.broadcast_latest_holder_commitment_txn(&args.tx_broadcaster, &args.logger);
                        }
                }

                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_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>)>()));
                for _ in 0..peer_count {
                        let peer_pubkey = Readable::read(reader)?;
                        let peer_state = PeerState {
                                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: Vec<events::Event> = Vec::with_capacity(cmp::min(event_count as usize, MAX_ALLOC_SIZE/mem::size_of::<events::Event>()));
                for _ in 0..event_count {
                        match MaybeReadable::read(reader)? {
                                Some(event) => pending_events_read.push(event),
                                None => continue,
                        }
                }

                let background_event_count: u64 = Readable::read(reader)?;
                let mut pending_background_events_read: Vec<BackgroundEvent> = Vec::with_capacity(cmp::min(background_event_count as usize, MAX_ALLOC_SIZE/mem::size_of::<BackgroundEvent>()));
                for _ in 0..background_event_count {
                        match <u8 as Readable>::read(reader)? {
                                0 => pending_background_events_read.push(BackgroundEvent::ClosingMonitorUpdate((Readable::read(reader)?, 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 pending_claiming_payments = Some(HashMap::new());
                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),
                        (7, fake_scid_rand_bytes, option),
                        (9, claimable_htlc_purposes, vec_type),
                        (11, probing_cookie_secret, option),
                });
                if fake_scid_rand_bytes.is_none() {
                        fake_scid_rand_bytes = Some(args.keys_manager.get_secure_random_bytes());
                }

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

                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);
                } else {
                        // 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() {
                                if by_id.get(&monitor.get_funding_txo().0.to_channel_id()).is_none() {
                                        for (htlc_source, htlc) in monitor.get_pending_outbound_htlcs() {
                                                if let HTLCSource::OutboundRoute { payment_id, session_priv, path, payment_secret, .. } = htlc_source {
                                                        if path.is_empty() {
                                                                log_error!(args.logger, "Got an empty path for a pending payment");
                                                                return Err(DecodeError::InvalidValue);
                                                        }
                                                        let path_amt = path.last().unwrap().fee_msat;
                                                        let mut session_priv_bytes = [0; 32];
                                                        session_priv_bytes[..].copy_from_slice(&session_priv[..]);
                                                        match pending_outbound_payments.as_mut().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), log_bytes!(htlc.payment_hash.0));
                                                                },
                                                                hash_map::Entry::Vacant(entry) => {
                                                                        let path_fee = path.get_path_fees();
                                                                        entry.insert(PendingOutboundPayment::Retryable {
                                                                                session_privs: [session_priv_bytes].iter().map(|a| *a).collect(),
                                                                                payment_hash: htlc.payment_hash,
                                                                                payment_secret,
                                                                                pending_amt_msat: path_amt,
                                                                                pending_fee_msat: Some(path_fee),
                                                                                total_msat: path_amt,
                                                                                starting_block_height: best_block_height,
                                                                        });
                                                                        log_info!(args.logger, "Added a pending payment for {} msat with payment hash {} for path with session priv {}",
                                                                                path_amt, log_bytes!(htlc.payment_hash.0),  log_bytes!(session_priv_bytes));
                                                                }
                                                        }
                                                }
                                        }
                                        for (htlc_source, htlc) in monitor.get_all_current_outbound_htlcs() {
                                                if let HTLCSource::PreviousHopData(prev_hop_data) = htlc_source {
                                                        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 {}",
                                                                                                log_bytes!(htlc.payment_hash.0), log_bytes!(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 {}",
                                                                                log_bytes!(htlc.payment_hash.0), log_bytes!(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 }
                                                        });
                                                }
                                        }
                                }
                        }
                }

                if !forward_htlcs.is_empty() {
                        // 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(events::Event::PendingHTLCsForwardable {
                                time_forwardable: Duration::from_secs(2),
                        });
                }

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

                let mut claimable_htlcs = HashMap::with_capacity(claimable_htlcs_list.len());
                if let Some(mut purposes) = claimable_htlc_purposes {
                        if purposes.len() != claimable_htlcs_list.len() {
                                return Err(DecodeError::InvalidValue);
                        }
                        for (purpose, (payment_hash, previous_hops)) in purposes.drain(..).zip(claimable_htlcs_list.drain(..)) {
                                claimable_htlcs.insert(payment_hash, (purpose, previous_hops));
                        }
                } 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, previous_hops) in claimable_htlcs_list.drain(..) {
                                if previous_hops.is_empty() {
                                        return Err(DecodeError::InvalidValue);
                                }
                                let purpose = match &previous_hops[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", log_bytes!(payment_hash.0));
                                                                                        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_htlcs.insert(payment_hash, (purpose, previous_hops));
                        }
                }

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

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

                let our_network_key = match args.keys_manager.get_node_secret(Recipient::Node) {
                        Ok(key) => key,
                        Err(()) => return Err(DecodeError::InvalidValue)
                };
                let our_network_pubkey = PublicKey::from_secret_key(&secp_ctx, &our_network_key);
                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 (chan_id, chan) in by_id.iter_mut() {
                        if chan.outbound_scid_alias() == 0 {
                                let mut outbound_scid_alias;
                                loop {
                                        outbound_scid_alias = fake_scid::Namespace::OutboundAlias
                                                .get_fake_scid(best_block_height, &genesis_hash, fake_scid_rand_bytes.as_ref().unwrap(), &args.keys_manager);
                                        if outbound_scid_aliases.insert(outbound_scid_alias) { break; }
                                }
                                chan.set_outbound_scid_alias(outbound_scid_alias);
                        } else if !outbound_scid_aliases.insert(chan.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.outbound_scid_alias());
                                return Err(DecodeError::InvalidValue);
                        }
                        if chan.is_usable() {
                                if short_to_chan_info.insert(chan.outbound_scid_alias(), (chan.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.outbound_scid_alias());
                                        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_purpose, claimable_htlcs)) = claimable_htlcs.remove(&payment_hash) {
                                        log_info!(args.logger, "Re-claiming HTLCs with payment hash {} as we've released the preimage to a ChannelMonitor!", log_bytes!(payment_hash.0));
                                        let mut claimable_amt_msat = 0;
                                        let mut receiver_node_id = Some(our_network_pubkey);
                                        let phantom_shared_secret = claimable_htlcs[0].prev_hop.phantom_shared_secret;
                                        if phantom_shared_secret.is_some() {
                                                let phantom_pubkey = args.keys_manager.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 claimable_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(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(events::Event::PaymentClaimed {
                                                receiver_node_id,
                                                payment_hash,
                                                purpose: payment_purpose,
                                                amount_msat: claimable_amt_msat,
                                        });
                                }
                        }
                }

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

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

                        channel_state: Mutex::new(ChannelHolder {
                                by_id,
                                pending_msg_events: Vec::new(),
                        }),
                        inbound_payment_key: expanded_inbound_key,
                        pending_inbound_payments: Mutex::new(pending_inbound_payments),
                        pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()),
                        pending_intercepted_htlcs: Mutex::new(pending_intercepted_htlcs.unwrap()),

                        forward_htlcs: Mutex::new(forward_htlcs),
                        claimable_payments: Mutex::new(ClaimablePayments { claimable_htlcs, 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_key,
                        our_network_pubkey,
                        secp_ctx,

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

                        per_peer_state: RwLock::new(per_peer_state),

                        pending_events: Mutex::new(pending_events_read),
                        pending_background_events: Mutex::new(pending_background_events_read),
                        total_consistency_lock: RwLock::new(()),
                        persistence_notifier: Notifier::new(),

                        keys_manager: args.keys_manager,
                        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);
                }

                //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 core::time::Duration;
        use core::sync::atomic::Ordering;
        use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
        use crate::ln::channelmanager::{self, inbound_payment, PaymentId, PaymentSendFailure};
        use crate::ln::functional_test_utils::*;
        use crate::ln::msgs;
        use crate::ln::msgs::ChannelMessageHandler;
        use crate::routing::router::{PaymentParameters, RouteParameters, find_route};
        use crate::util::errors::APIError;
        use crate::util::events::{Event, HTLCDestination, MessageSendEvent, MessageSendEventsProvider, ClosureReason};
        use crate::util::test_utils;
        use crate::chain::keysinterface::KeysInterface;

        #[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.await_persistable_update_timeout(Duration::from_millis(1)));
                assert!(nodes[1].node.await_persistable_update_timeout(Duration::from_millis(1)));
                assert!(nodes[2].node.await_persistable_update_timeout(Duration::from_millis(1)));

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

                // 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()[0].clone();
                let node_b_chan_info = nodes[1].node.list_channels()[0].clone();

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

                // 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.await_persistable_update_timeout(Duration::from_millis(1)));

                // 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.await_persistable_update_timeout(Duration::from_millis(1)));
                assert!(!nodes[1].node.await_persistable_update_timeout(Duration::from_millis(1)));

                // 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.await_persistable_update_timeout(Duration::from_millis(1)));
                assert!(!nodes[1].node.await_persistable_update_timeout(Duration::from_millis(1)));
                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.await_persistable_update_timeout(Duration::from_millis(1)));
                assert!(nodes[1].node.await_persistable_update_timeout(Duration::from_millis(1)));
                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, channelmanager::provided_init_features(), channelmanager::provided_init_features());

                // 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.add_new_pending_payment(our_payment_hash, Some(payment_secret), payment_id, &mpp_route).unwrap();
                nodes[0].node.send_payment_along_path(&mpp_route.paths[0], &route.payment_params, &our_payment_hash, &Some(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), 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.send_payment_along_path(&mpp_route.paths[1], &route.payment_params, &our_payment_hash, &Some(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]);
                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(), 3);
                match events[0] {
                        Event::PaymentSent { payment_id: ref id, payment_preimage: ref preimage, payment_hash: ref hash, .. } => {
                                assert_eq!(Some(payment_id), *id);
                                assert_eq!(payment_preimage, *preimage);
                                assert_eq!(our_payment_hash, *hash);
                        },
                        _ => 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"),
                }
                match events[2] {
                        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() {
                // (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.
                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, channelmanager::provided_init_features(), channelmanager::provided_init_features());
                let scorer = test_utils::TestScorer::with_penalty(0);
                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 {
                        payment_params: PaymentParameters::for_keysend(expected_route.last().unwrap().node.get_our_node_id()),
                        final_value_msat: 100_000,
                        final_cltv_expiry_delta: TEST_FINAL_CLTV,
                };
                let route = find_route(
                        &nodes[0].node.get_our_node_id(), &route_params, &nodes[0].network_graph,
                        None, nodes[0].logger, &scorer, &random_seed_bytes
                ).unwrap();
                nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage), 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, &random_seed_bytes
                ).unwrap();
                let payment_hash = nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage), 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(&route, payment_hash, &Some(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);
        }

        #[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();
                nodes[0].node.peer_connected(&payee_pubkey, &msgs::Init { features: channelmanager::provided_init_features(), remote_network_address: None }).unwrap();
                nodes[1].node.peer_connected(&payer_pubkey, &msgs::Init { features: channelmanager::provided_init_features(), remote_network_address: None }).unwrap();

                let _chan = create_chan_between_nodes(&nodes[0], &nodes[1], channelmanager::provided_init_features(), channelmanager::provided_init_features());
                let route_params = RouteParameters {
                        payment_params: PaymentParameters::for_keysend(payee_pubkey),
                        final_value_msat: 10_000,
                        final_cltv_expiry_delta: 40,
                };
                let network_graph = nodes[0].network_graph;
                let first_hops = nodes[0].node.list_usable_channels();
                let scorer = test_utils::TestScorer::with_penalty(0);
                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, &random_seed_bytes
                ).unwrap();

                let test_preimage = PaymentPreimage([42; 32]);
                let mismatch_payment_hash = PaymentHash([43; 32]);
                let session_privs = nodes[0].node.add_new_pending_payment(mismatch_payment_hash, None, PaymentId(mismatch_payment_hash.0), &route).unwrap();
                nodes[0].node.send_payment_internal(&route, mismatch_payment_hash, &None, 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".to_string(), "Payment preimage didn't match payment hash".to_string(), 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.
                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();
                nodes[0].node.peer_connected(&payee_pubkey, &msgs::Init { features: channelmanager::provided_init_features(), remote_network_address: None }).unwrap();
                nodes[1].node.peer_connected(&payer_pubkey, &msgs::Init { features: channelmanager::provided_init_features(), remote_network_address: None }).unwrap();

                let _chan = create_chan_between_nodes(&nodes[0], &nodes[1], channelmanager::provided_init_features(), channelmanager::provided_init_features());
                let route_params = RouteParameters {
                        payment_params: PaymentParameters::for_keysend(payee_pubkey),
                        final_value_msat: 10_000,
                        final_cltv_expiry_delta: 40,
                };
                let network_graph = nodes[0].network_graph;
                let first_hops = nodes[0].node.list_usable_channels();
                let scorer = test_utils::TestScorer::with_penalty(0);
                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, &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).into_inner());
                let session_privs = nodes[0].node.add_new_pending_payment(payment_hash, Some(test_secret), PaymentId(payment_hash.0), &route).unwrap();
                nodes[0].node.send_payment_internal(&route, payment_hash, &Some(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".to_string(), "We don't support MPP keysend payments".to_string(), 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, channelmanager::provided_init_features(), channelmanager::provided_init_features()).0.contents.short_channel_id;
                let chan_2_id = create_announced_chan_between_nodes(&nodes, 0, 2, channelmanager::provided_init_features(), channelmanager::provided_init_features()).0.contents.short_channel_id;
                let chan_3_id = create_announced_chan_between_nodes(&nodes, 1, 3, channelmanager::provided_init_features(), channelmanager::provided_init_features()).0.contents.short_channel_id;
                let chan_4_id = create_announced_chan_between_nodes(&nodes, 2, 3, channelmanager::provided_init_features(), channelmanager::provided_init_features()).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][0].pubkey = nodes[1].node.get_our_node_id();
                route.paths[0][0].short_channel_id = chan_1_id;
                route.paths[0][1].short_channel_id = chan_3_id;
                route.paths[1][0].pubkey = nodes[2].node.get_our_node_id();
                route.paths[1][0].short_channel_id = chan_2_id;
                route.paths[1][1].short_channel_id = chan_4_id;

                match nodes[0].node.send_payment(&route, payment_hash, &None, 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 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".to_string(), "Failing HTLC with user-generated payment_hash".to_string(), 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).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(), channelmanager::provided_init_features(), &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(), channelmanager::provided_init_features(), &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 = &tx.txid().into_inner();
                {
                        // 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));

                        // 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);
                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(), &channelmanager::provided_init_features(), &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(), &channelmanager::provided_init_features(), &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);
                check_closed_event!(nodes[1], 1, ClosureReason::CooperativeClosure);
        }
}

#[cfg(all(any(test, feature = "_test_utils"), feature = "_bench_unstable"))]
pub mod bench {
        use crate::chain::Listen;
        use crate::chain::chainmonitor::{ChainMonitor, Persist};
        use crate::chain::keysinterface::{KeysManager, KeysInterface, InMemorySigner};
        use crate::ln::channelmanager::{self, BestBlock, ChainParameters, ChannelManager, PaymentHash, PaymentPreimage, PaymentId};
        use crate::ln::functional_test_utils::*;
        use crate::ln::msgs::{ChannelMessageHandler, Init};
        use crate::routing::gossip::NetworkGraph;
        use crate::routing::router::{PaymentParameters, get_route};
        use crate::util::test_utils;
        use crate::util::config::UserConfig;
        use crate::util::events::{Event, MessageSendEvent, MessageSendEventsProvider};

        use bitcoin::hashes::Hash;
        use bitcoin::hashes::sha256::Hash as Sha256;
        use bitcoin::{Block, BlockHeader, PackedLockTime, Transaction, TxMerkleNode, TxOut};

        use crate::sync::{Arc, Mutex};

        use test::Bencher;

        struct NodeHolder<'a, P: Persist<InMemorySigner>> {
                node: &'a 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 test_utils::TestFeeEstimator, &'a test_utils::TestLogger>,
        }

        #[cfg(test)]
        #[bench]
        fn bench_sends(bench: &mut Bencher) {
                bench_two_sends(bench, test_utils::TestPersister::new(), test_utils::TestPersister::new());
        }

        pub fn bench_two_sends<P: Persist<InMemorySigner>>(bench: &mut Bencher, 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_hash = bitcoin::blockdata::constants::genesis_block(network).header.block_hash();

                let tx_broadcaster = test_utils::TestBroadcaster{txn_broadcasted: Mutex::new(Vec::new()), blocks: Arc::new(Mutex::new(Vec::new()))};
                let fee_estimator = test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) };

                let mut config: UserConfig = Default::default();
                config.channel_handshake_config.minimum_depth = 1;

                let logger_a = test_utils::TestLogger::with_id("node a".to_owned());
                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, &logger_a, &keys_manager_a, config.clone(), ChainParameters {
                        network,
                        best_block: BestBlock::from_genesis(network),
                });
                let node_a_holder = NodeHolder { 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, &logger_b, &keys_manager_b, config.clone(), ChainParameters {
                        network,
                        best_block: BestBlock::from_genesis(network),
                });
                let node_b_holder = NodeHolder { node: &node_b };

                node_a.peer_connected(&node_b.get_our_node_id(), &Init { features: channelmanager::provided_init_features(), remote_network_address: None }).unwrap();
                node_b.peer_connected(&node_a.get_our_node_id(), &Init { features: channelmanager::provided_init_features(), remote_network_address: None }).unwrap();
                node_a.create_channel(node_b.get_our_node_id(), 8_000_000, 100_000_000, 42, None).unwrap();
                node_b.handle_open_channel(&node_a.get_our_node_id(), channelmanager::provided_init_features(), &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(), channelmanager::provided_init_features(), &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: PackedLockTime::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()));
                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()));

                assert_eq!(&tx_broadcaster.txn_broadcasted.lock().unwrap()[..], &[tx.clone()]);

                let block = Block {
                        header: BlockHeader { version: 0x20000000, prev_blockhash: genesis_hash, merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42 },
                        txdata: 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 dummy_graph = NetworkGraph::new(genesis_hash, &logger_a);

                let mut payment_count: u64 = 0;
                macro_rules! send_payment {
                        ($node_a: expr, $node_b: expr) => {
                                let usable_channels = $node_a.list_usable_channels();
                                let payment_params = PaymentParameters::from_node_id($node_b.get_our_node_id())
                                        .with_features(channelmanager::provided_invoice_features());
                                let scorer = test_utils::TestScorer::with_penalty(0);
                                let seed = [3u8; 32];
                                let keys_manager = KeysManager::new(&seed, 42, 42);
                                let random_seed_bytes = keys_manager.get_secure_random_bytes();
                                let route = get_route(&$node_a.get_our_node_id(), &payment_params, &dummy_graph.read_only(),
                                        Some(&usable_channels.iter().map(|r| r).collect::<Vec<_>>()), 10_000, TEST_FINAL_CLTV, &logger_a, &scorer, &random_seed_bytes).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[..]).into_inner());
                                let payment_secret = $node_b.create_inbound_payment_for_hash(payment_hash, None, 7200).unwrap();

                                $node_a.send_payment(&route, payment_hash, &Some(payment_secret), PaymentId(payment_hash.0)).unwrap();
                                let payment_event = SendEvent::from_event($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!(NodeHolder { 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!(NodeHolder { node: &$node_a }, MessageSendEvent::SendRevokeAndACK, $node_b.get_our_node_id()));

                                expect_pending_htlcs_forwardable!(NodeHolder { node: &$node_b });
                                expect_payment_claimable!(NodeHolder { node: &$node_b }, payment_hash, payment_secret, 10_000);
                                $node_b.claim_funds(payment_preimage);
                                expect_payment_claimed!(NodeHolder { node: &$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!(NodeHolder { 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!(NodeHolder { node: &$node_b }, MessageSendEvent::SendRevokeAndACK, $node_a.get_our_node_id()));

                                expect_payment_sent!(NodeHolder { node: &$node_a }, payment_preimage);
                        }
                }

                bench.iter(|| {
                        send_payment!(node_a, node_b);
                        send_payment!(node_b, node_a);
                });
        }
}