Raise max to_self_delay.

[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 routing::router::get_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).
//!

use bitcoin::blockdata::block::{Block, BlockHeader};
use bitcoin::blockdata::constants::genesis_block;
use bitcoin::network::constants::Network;

use bitcoin::hashes::{Hash, HashEngine};
use bitcoin::hashes::hmac::{Hmac, HmacEngine};
use bitcoin::hashes::sha256::Hash as Sha256;
use bitcoin::hashes::sha256d::Hash as Sha256dHash;
use bitcoin::hashes::cmp::fixed_time_eq;
use bitcoin::hash_types::BlockHash;

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

use chain;
use chain::Watch;
use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, ChannelMonitorUpdateErr, HTLC_FAIL_BACK_BUFFER, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY, MonitorEvent, CLOSED_CHANNEL_UPDATE_ID};
use chain::transaction::{OutPoint, TransactionData};
use ln::channel::{Channel, ChannelError};
use ln::features::{InitFeatures, NodeFeatures};
use routing::router::{Route, RouteHop};
use ln::msgs;
use ln::msgs::NetAddress;
use ln::onion_utils;
use ln::msgs::{ChannelMessageHandler, DecodeError, LightningError, OptionalField};
use chain::keysinterface::{Sign, KeysInterface, KeysManager, InMemorySigner};
use util::config::UserConfig;
use util::events::{Event, EventsProvider, MessageSendEvent, MessageSendEventsProvider};
use util::{byte_utils, events};
use util::ser::{Readable, ReadableArgs, MaybeReadable, Writeable, Writer};
use util::chacha20::{ChaCha20, ChaChaReader};
use util::logger::Logger;
use util::errors::APIError;

use std::{cmp, mem};
use std::collections::{HashMap, hash_map, HashSet};
use std::io::{Cursor, Read};
use std::sync::{Arc, Condvar, Mutex, MutexGuard, RwLock, RwLockReadGuard};
use std::sync::atomic::{AtomicUsize, Ordering};
use std::time::Duration;
#[cfg(any(test, feature = "allow_wallclock_use"))]
use std::time::Instant;
use std::marker::{Sync, Send};
use std::ops::Deref;
use bitcoin::hashes::hex::ToHex;

// 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
enum PendingHTLCRouting {
        Forward {
                onion_packet: msgs::OnionPacket,
                short_channel_id: u64, // This should be NonZero<u64> eventually when we bump MSRV
        },
        Receive {
                payment_data: Option<msgs::FinalOnionHopData>,
                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 {
        routing: PendingHTLCRouting,
        incoming_shared_secret: [u8; 32],
        payment_hash: PaymentHash,
        pub(super) amt_to_forward: 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) enum HTLCForwardInfo {
        AddHTLC {
                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.
                prev_short_channel_id: u64,
                prev_htlc_id: u64,
                prev_funding_outpoint: OutPoint,
        },
        FailHTLC {
                htlc_id: u64,
                err_packet: msgs::OnionErrorPacket,
        },
}

/// Tracks the inbound corresponding to an outbound HTLC
#[derive(Clone, PartialEq)]
pub(crate) struct HTLCPreviousHopData {
        short_channel_id: u64,
        htlc_id: u64,
        incoming_packet_shared_secret: [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,
}

struct ClaimableHTLC {
        prev_hop: HTLCPreviousHopData,
        value: u64,
        /// Filled in when the HTLC was received with a payment_secret packet, which contains a
        /// total_msat (which may differ from value if this is a Multi-Path Payment) and a
        /// payment_secret which prevents path-probing attacks and can associate different HTLCs which
        /// are part of the same payment.
        payment_data: Option<msgs::FinalOnionHopData>,
        cltv_expiry: u32,
}

/// Tracks the inbound corresponding to an outbound HTLC
#[derive(Clone, PartialEq)]
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,
        },
}
#[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,
                }
        }
}

#[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
pub(super) enum HTLCFailReason {
        LightningError {
                err: msgs::OnionErrorPacket,
        },
        Reason {
                failure_code: u16,
                data: Vec<u8>,
        }
}

/// payment_hash type, use to cross-lock hop
/// (C-not exported) as we just use [u8; 32] directly
#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
pub struct PaymentHash(pub [u8;32]);
/// payment_preimage type, use to route payment between hop
/// (C-not exported) as we just use [u8; 32] directly
#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
pub struct PaymentPreimage(pub [u8;32]);
/// payment_secret type, use to authenticate sender to the receiver and tie MPP HTLCs together
/// (C-not exported) as we just use [u8; 32] directly
#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
pub struct PaymentSecret(pub [u8;32]);

type ShutdownResult = (Option<(OutPoint, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash)>);

/// 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,
        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
                                        },
                                },
                        },
                        shutdown_finish: None,
                }
        }
        #[inline]
        fn ignore_no_close(err: String) -> Self {
                Self {
                        err: LightningError {
                                err,
                                action: msgs::ErrorAction::IgnoreError,
                        },
                        shutdown_finish: None,
                }
        }
        #[inline]
        fn from_no_close(err: msgs::LightningError) -> Self {
                Self { err, shutdown_finish: None }
        }
        #[inline]
        fn from_finish_shutdown(err: String, channel_id: [u8; 32], 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
                                        },
                                },
                        },
                        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::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
                                                },
                                        },
                                },
                                ChannelError::CloseDelayBroadcast(msg) => LightningError {
                                        err: msg.clone(),
                                        action: msgs::ErrorAction::SendErrorMessage {
                                                msg: msgs::ErrorMessage {
                                                        channel_id,
                                                        data: msg
                                                },
                                        },
                                },
                        },
                        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,
}

// Note this is only exposed in cfg(test):
pub(super) struct ChannelHolder<Signer: Sign> {
        pub(super) by_id: HashMap<[u8; 32], Channel<Signer>>,
        pub(super) short_to_id: HashMap<u64, [u8; 32]>,
        /// short channel id -> forward infos. Key of 0 means payments received
        /// Note that while this is held in the same mutex as the channels themselves, no consistency
        /// guarantees are made about the existence of a channel with the short id here, nor the short
        /// ids in the PendingHTLCInfo!
        pub(super) forward_htlcs: HashMap<u64, Vec<HTLCForwardInfo>>,
        /// (payment_hash, payment_secret) -> Vec<HTLCs> for tracking HTLCs that
        /// were to us and can be failed/claimed by the user
        /// Note that while this is held in the same mutex as the channels themselves, no consistency
        /// guarantees are made about the channels given here actually existing anymore by the time you
        /// go to read them!
        claimable_htlcs: HashMap<(PaymentHash, Option<PaymentSecret>), Vec<ClaimableHTLC>>,
        /// 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_chan_freshness_every_min, 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)),
}

/// 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,
}

#[cfg(not(any(target_pointer_width = "32", target_pointer_width = "64")))]
const ERR: () = "You need at least 32 bit pointers (well, usize, but we'll assume they're the same) for ChannelManager::latest_block_height";

/// 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.
pub type SimpleArcChannelManager<M, T, F, L> = ChannelManager<InMemorySigner, 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.
pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, M, T, F, L> = ChannelManager<InMemorySigner, &'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_chan_freshness_every_min 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.
pub struct ChannelManager<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
                                L::Target: Logger,
{
        default_configuration: UserConfig,
        genesis_hash: BlockHash,
        fee_estimator: F,
        chain_monitor: M,
        tx_broadcaster: T,

        #[cfg(test)]
        pub(super) latest_block_height: AtomicUsize,
        #[cfg(not(test))]
        latest_block_height: AtomicUsize,
        last_block_hash: RwLock<BlockHash>,
        secp_ctx: Secp256k1<secp256k1::All>,

        #[cfg(any(test, feature = "_test_utils"))]
        pub(super) channel_state: Mutex<ChannelHolder<Signer>>,
        #[cfg(not(any(test, feature = "_test_utils")))]
        channel_state: Mutex<ChannelHolder<Signer>>,
        our_network_key: SecretKey,

        /// Used to track the last value sent in a node_announcement "timestamp" field. We ensure this
        /// value increases strictly since we don't assume access to a time source.
        last_node_announcement_serial: 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.
        per_peer_state: RwLock<HashMap<PublicKey, Mutex<PeerState>>>,

        pending_events: Mutex<Vec<events::Event>>,
        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::new(..)` and pass the lock to it, to ensure the PersistenceNotifier
        /// the lock contains sends out a notification when the lock is released.
        total_consistency_lock: RwLock<()>,

        persistence_notifier: PersistenceNotifier,

        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`.
pub struct ChainParameters {
        /// The network for determining the `chain_hash` in Lightning messages.
        pub network: Network,

        /// The hash of the latest block successfully connected.
        pub latest_hash: BlockHash,

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

/// 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` that 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).
struct PersistenceNotifierGuard<'a> {
        persistence_notifier: &'a PersistenceNotifier,
        // We hold onto this result so the lock doesn't get released immediately.
        _read_guard: RwLockReadGuard<'a, ()>,
}

impl<'a> PersistenceNotifierGuard<'a> {
        fn new(lock: &'a RwLock<()>, notifier: &'a PersistenceNotifier) -> Self {
                let read_guard = lock.read().unwrap();

                Self {
                        persistence_notifier: notifier,
                        _read_guard: read_guard,
                }
        }
}

impl<'a> Drop for PersistenceNotifierGuard<'a> {
        fn drop(&mut self) {
                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).
pub(crate) 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. This should always be a few blocks greater than channelmonitor::CLTV_CLAIM_BUFFER,
/// ie 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).
const CLTV_EXPIRY_DELTA: u16 = 6 * 12; //TODO?
pub(super) const CLTV_FAR_FAR_AWAY: u32 = 6 * 24 * 7; //TODO?

// 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 = 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 inbound claim. See
// ChannelMontior::would_broadcast_at_height for a description of why this is needed.
#[deny(const_err)]
#[allow(dead_code)]
const CHECK_CLTV_EXPIRY_SANITY_2: u32 = CLTV_EXPIRY_DELTA as u32 - LATENCY_GRACE_PERIOD_BLOCKS - 2*CLTV_CLAIM_BUFFER;

/// Details of a channel, as returned by ChannelManager::list_channels and ChannelManager::list_usable_channels
#[derive(Clone)]
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],
        /// The position of the funding transaction in the chain. None if the funding transaction has
        /// not yet been confirmed and the channel fully opened.
        pub short_channel_id: Option<u64>,
        /// The node_id of our counterparty
        pub remote_network_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 counterparty_features: InitFeatures,
        /// The value, in satoshis, of this channel as appears in the funding output
        pub channel_value_satoshis: u64,
        /// The user_id passed in to create_channel, or 0 if the channel was inbound.
        pub user_id: 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, who's 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.
        pub outbound_capacity_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, who's 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.
        pub inbound_capacity_msat: u64,
        /// True if the channel is (a) confirmed and funding_locked messages have been exchanged, (b)
        /// the peer is connected, and (c) no monitor update failure is pending resolution.
        pub is_live: bool,
}

/// 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. No channel state has been changed or messages sent to peers, and
        /// once you've changed the parameter at error, you can freely retry the payment in full.
        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. No channel state has been changed or messages
        /// sent to peers, and once you've changed the parameter at error, you can freely retry the
        /// payment in full.
        ///
        /// The results here are ordered the same as the paths in the route object which was passed to
        /// send_payment.
        PathParameterError(Vec<Result<(), APIError>>),
        /// All paths which were attempted failed to send, with no channel state change taking place.
        /// You can freely retry the payment in full (though you probably want to do so over different
        /// paths than the ones selected).
        AllFailedRetrySafe(Vec<APIError>),
        /// 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 Errs which are not APIError::MonitorUpdateFailed can be safely
        /// retried (though there is currently no API with which to do so).
        ///
        /// Any entries which contain Err(APIError::MonitorUpdateFailed) 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 channel_monitor_updated is called on the next-hop channel
        /// with the latest update_id.
        PartialFailure(Vec<Result<(), APIError>>),
}

macro_rules! handle_error {
        ($self: ident, $internal: expr, $counterparty_node_id: expr) => {
                match $internal {
                        Ok(msg) => Ok(msg),
                        Err(MsgHandleErrInternal { err, shutdown_finish }) => {
                                #[cfg(debug_assertions)]
                                {
                                        // In testing, ensure there are no deadlocks where the lock is already held upon
                                        // entering the macro.
                                        assert!($self.channel_state.try_lock().is_ok());
                                }

                                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
                                                });
                                        }
                                }

                                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! break_chan_entry {
        ($self: ident, $res: expr, $channel_state: expr, $entry: expr) => {
                match $res {
                        Ok(res) => res,
                        Err(ChannelError::Ignore(msg)) => {
                                break Err(MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore(msg), $entry.key().clone()))
                        },
                        Err(ChannelError::Close(msg)) => {
                                log_trace!($self.logger, "Closing channel {} due to Close-required error: {}", log_bytes!($entry.key()[..]), msg);
                                let (channel_id, mut chan) = $entry.remove_entry();
                                if let Some(short_id) = chan.get_short_channel_id() {
                                        $channel_state.short_to_id.remove(&short_id);
                                }
                                break Err(MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, chan.force_shutdown(true), $self.get_channel_update(&chan).ok()))
                        },
                        Err(ChannelError::CloseDelayBroadcast(_)) => { panic!("Wait is only generated on receipt of channel_reestablish, which is handled by try_chan_entry, we don't bother to support it here"); }
                }
        }
}

macro_rules! try_chan_entry {
        ($self: ident, $res: expr, $channel_state: expr, $entry: expr) => {
                match $res {
                        Ok(res) => res,
                        Err(ChannelError::Ignore(msg)) => {
                                return Err(MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore(msg), $entry.key().clone()))
                        },
                        Err(ChannelError::Close(msg)) => {
                                log_trace!($self.logger, "Closing channel {} due to Close-required error: {}", log_bytes!($entry.key()[..]), msg);
                                let (channel_id, mut chan) = $entry.remove_entry();
                                if let Some(short_id) = chan.get_short_channel_id() {
                                        $channel_state.short_to_id.remove(&short_id);
                                }
                                return Err(MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, chan.force_shutdown(true), $self.get_channel_update(&chan).ok()))
                        },
                        Err(ChannelError::CloseDelayBroadcast(msg)) => {
                                log_error!($self.logger, "Channel {} need to be shutdown but closing transactions not broadcast due to {}", log_bytes!($entry.key()[..]), msg);
                                let (channel_id, mut chan) = $entry.remove_entry();
                                if let Some(short_id) = chan.get_short_channel_id() {
                                        $channel_state.short_to_id.remove(&short_id);
                                }
                                let shutdown_res = chan.force_shutdown(false);
                                return Err(MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, shutdown_res, $self.get_channel_update(&chan).ok()))
                        }
                }
        }
}

macro_rules! handle_monitor_err {
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
                handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, Vec::new(), Vec::new())
        };
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr) => {
                match $err {
                        ChannelMonitorUpdateErr::PermanentFailure => {
                                log_error!($self.logger, "Closing channel {} due to monitor update PermanentFailure", log_bytes!($entry.key()[..]));
                                let (channel_id, mut chan) = $entry.remove_entry();
                                if let Some(short_id) = chan.get_short_channel_id() {
                                        $channel_state.short_to_id.remove(&short_id);
                                }
                                // 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(), channel_id, chan.force_shutdown(true), $self.get_channel_update(&chan).ok()));
                                res
                        },
                        ChannelMonitorUpdateErr::TemporaryFailure => {
                                log_info!($self.logger, "Disabling channel {} due to monitor update TemporaryFailure. On restore will send {} and process {} forwards and {} fails",
                                                log_bytes!($entry.key()[..]),
                                                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(),
                                                (&$failed_fails as &Vec<(HTLCSource, PaymentHash, HTLCFailReason)>).len());
                                if !$resend_commitment {
                                        debug_assert!($action_type == RAACommitmentOrder::RevokeAndACKFirst || !$resend_raa);
                                }
                                if !$resend_raa {
                                        debug_assert!($action_type == RAACommitmentOrder::CommitmentFirst || !$resend_commitment);
                                }
                                $entry.get_mut().monitor_update_failed($resend_raa, $resend_commitment, $failed_forwards, $failed_fails);
                                Err(MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore("Failed to update ChannelMonitor".to_owned()), *$entry.key()))
                        },
                }
        }
}

macro_rules! return_monitor_err {
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
                return handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment);
        };
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr) => {
                return handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, $failed_forwards, $failed_fails);
        }
}

// Does not break in case of TemporaryFailure!
macro_rules! maybe_break_monitor_err {
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
                match (handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment), $err) {
                        (e, ChannelMonitorUpdateErr::PermanentFailure) => {
                                break e;
                        },
                        (_, ChannelMonitorUpdateErr::TemporaryFailure) => { },
                }
        }
}

impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        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.
        ///
        /// panics if channel_value_satoshis is >= `MAX_FUNDING_SATOSHIS`!
        ///
        /// 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());

                ChannelManager {
                        default_configuration: config.clone(),
                        genesis_hash: genesis_block(params.network).header.block_hash(),
                        fee_estimator: fee_est,
                        chain_monitor,
                        tx_broadcaster,

                        latest_block_height: AtomicUsize::new(params.latest_height),
                        last_block_hash: RwLock::new(params.latest_hash),
                        secp_ctx,

                        channel_state: Mutex::new(ChannelHolder{
                                by_id: HashMap::new(),
                                short_to_id: HashMap::new(),
                                forward_htlcs: HashMap::new(),
                                claimable_htlcs: HashMap::new(),
                                pending_msg_events: Vec::new(),
                        }),
                        our_network_key: keys_manager.get_node_secret(),

                        last_node_announcement_serial: 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: PersistenceNotifier::new(),

                        keys_manager,

                        logger,
                }
        }

        /// Creates a new outbound channel to the given remote node and with the given value.
        ///
        /// user_id will be provided back as user_channel_id in FundingGenerationReady and
        /// FundingBroadcastSafe events to allow tracking of which events correspond with which
        /// create_channel call. Note that user_channel_id defaults to 0 for inbound channels, so you
        /// may wish to avoid using 0 for user_id here.
        ///
        /// If successful, will generate a SendOpenChannel message event, so you should probably poll
        /// PeerManager::process_events afterwards.
        ///
        /// Raises APIError::APIMisuseError when channel_value_satoshis > 2**24 or push_msat is
        /// greater than channel_value_satoshis * 1k or channel_value_satoshis is < 1000.
        pub fn create_channel(&self, their_network_key: PublicKey, channel_value_satoshis: u64, push_msat: u64, user_id: u64, override_config: Option<UserConfig>) -> Result<(), 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 config = if override_config.is_some() { override_config.as_ref().unwrap() } else { &self.default_configuration };
                let channel = Channel::new_outbound(&self.fee_estimator, &self.keys_manager, their_network_key, channel_value_satoshis, push_msat, user_id, config)?;
                let res = channel.get_open_channel(self.genesis_hash.clone());

                let _persistence_guard = PersistenceNotifierGuard::new(&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 mut channel_state = self.channel_state.lock().unwrap();
                match channel_state.by_id.entry(channel.channel_id()) {
                        hash_map::Entry::Occupied(_) => {
                                if cfg!(feature = "fuzztarget") {
                                        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(())
        }

        fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<Signer>)) -> bool>(&self, f: Fn) -> Vec<ChannelDetails> {
                let mut res = Vec::new();
                {
                        let channel_state = self.channel_state.lock().unwrap();
                        res.reserve(channel_state.by_id.len());
                        for (channel_id, channel) in channel_state.by_id.iter().filter(f) {
                                let (inbound_capacity_msat, outbound_capacity_msat) = channel.get_inbound_outbound_available_balance_msat();
                                res.push(ChannelDetails {
                                        channel_id: (*channel_id).clone(),
                                        short_channel_id: channel.get_short_channel_id(),
                                        remote_network_id: channel.get_counterparty_node_id(),
                                        counterparty_features: InitFeatures::empty(),
                                        channel_value_satoshis: channel.get_value_satoshis(),
                                        inbound_capacity_msat,
                                        outbound_capacity_msat,
                                        user_id: channel.get_user_id(),
                                        is_live: channel.is_live(),
                                });
                        }
                }
                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.remote_network_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
        /// get_route to ensure non-announced channels are used.
        ///
        /// These are guaranteed to have their is_live value set to true, see the documentation for
        /// ChannelDetails::is_live for more info on exactly what the criteria are.
        pub fn list_usable_channels(&self) -> Vec<ChannelDetails> {
                // Note we use is_live here instead of usable which leads to somewhat confused
                // internal/external nomenclature, but that's ok cause that's probably what the user
                // really wanted anyway.
                self.list_channels_with_filter(|&(_, ref channel)| channel.is_live())
        }

        /// 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.
        ///
        /// May generate a SendShutdown message event on success, which should be relayed.
        pub fn close_channel(&self, channel_id: &[u8; 32]) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);

                let (mut failed_htlcs, 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(channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_entry) => {
                                        let (shutdown_msg, failed_htlcs) = chan_entry.get_mut().get_shutdown()?;
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                node_id: chan_entry.get().get_counterparty_node_id(),
                                                msg: shutdown_msg
                                        });
                                        if chan_entry.get().is_shutdown() {
                                                if let Some(short_id) = chan_entry.get().get_short_channel_id() {
                                                        channel_state.short_to_id.remove(&short_id);
                                                }
                                                (failed_htlcs, Some(chan_entry.remove_entry().1))
                                        } else { (failed_htlcs, None) }
                                },
                                hash_map::Entry::Vacant(_) => return Err(APIError::ChannelUnavailable{err: "No such channel".to_owned()})
                        }
                };
                for htlc_source in failed_htlcs.drain(..) {
                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() });
                }
                let chan_update = if let Some(chan) = chan_option {
                        if let Ok(update) = self.get_channel_update(&chan) {
                                Some(update)
                        } else { None }
                } else { None };

                if let Some(update) = chan_update {
                        let mut channel_state = self.channel_state.lock().unwrap();
                        channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                msg: update
                        });
                }

                Ok(())
        }

        #[inline]
        fn finish_force_close_channel(&self, shutdown_res: ShutdownResult) {
                let (monitor_update_option, mut failed_htlcs) = shutdown_res;
                log_trace!(self.logger, "Finishing force-closure of channel {} HTLCs to fail", failed_htlcs.len());
                for htlc_source in failed_htlcs.drain(..) {
                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() });
                }
                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);
                }
        }

        fn force_close_channel_with_peer(&self, channel_id: &[u8; 32], peer_node_id: Option<&PublicKey>) -> Result<(), 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 let Some(node_id) = peer_node_id {
                                        if chan.get().get_counterparty_node_id() != *node_id {
                                                // Error or Ok here doesn't matter - the result is only exposed publicly
                                                // when peer_node_id is None anyway.
                                                return Ok(());
                                        }
                                }
                                if let Some(short_id) = chan.get().get_short_channel_id() {
                                        channel_state.short_to_id.remove(&short_id);
                                }
                                chan.remove_entry().1
                        } else {
                                return Err(APIError::ChannelUnavailable{err: "No such channel".to_owned()});
                        }
                };
                log_trace!(self.logger, "Force-closing channel {}", log_bytes!(channel_id[..]));
                self.finish_force_close_channel(chan.force_shutdown(true));
                if let Ok(update) = self.get_channel_update(&chan) {
                        let mut channel_state = self.channel_state.lock().unwrap();
                        channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                msg: update
                        });
                }

                Ok(())
        }

        /// Force closes a channel, immediately broadcasting the latest local commitment transaction to
        /// the chain and rejecting new HTLCs on the given channel. Fails if channel_id is unknown to the manager.
        pub fn force_close_channel(&self, channel_id: &[u8; 32]) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                self.force_close_channel_with_peer(channel_id, None)
        }

        /// 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(&self) {
                for chan in self.list_channels() {
                        let _ = self.force_close_channel(&chan.channel_id);
                }
        }

        fn decode_update_add_htlc_onion(&self, msg: &msgs::UpdateAddHTLC) -> (PendingHTLCStatus, MutexGuard<ChannelHolder<Signer>>) {
                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,
                                        })), self.channel_state.lock().unwrap());
                                }
                        }
                }

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

                let shared_secret = {
                        let mut arr = [0; 32];
                        arr.copy_from_slice(&SharedSecret::new(&msg.onion_routing_packet.public_key.unwrap(), &self.our_network_key)[..]);
                        arr
                };
                let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(&shared_secret);

                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);
                }

                let mut hmac = HmacEngine::<Sha256>::new(&mu);
                hmac.input(&msg.onion_routing_packet.hop_data);
                hmac.input(&msg.payment_hash.0[..]);
                if !fixed_time_eq(&Hmac::from_engine(hmac).into_inner(), &msg.onion_routing_packet.hmac) {
                        return_malformed_err!("HMAC Check failed", 0x8000 | 0x4000 | 5);
                }

                let mut channel_state = None;
                macro_rules! return_err {
                        ($msg: expr, $err_code: expr, $data: expr) => {
                                {
                                        log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
                                        if channel_state.is_none() {
                                                channel_state = Some(self.channel_state.lock().unwrap());
                                        }
                                        return (PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
                                                channel_id: msg.channel_id,
                                                htlc_id: msg.htlc_id,
                                                reason: onion_utils::build_first_hop_failure_packet(&shared_secret, $err_code, $data),
                                        })), channel_state.unwrap());
                                }
                        }
                }

                let mut chacha = ChaCha20::new(&rho, &[0u8; 8]);
                let mut chacha_stream = ChaChaReader { chacha: &mut chacha, read: Cursor::new(&msg.onion_routing_packet.hop_data[..]) };
                let (next_hop_data, next_hop_hmac) = {
                        match msgs::OnionHopData::read(&mut chacha_stream) {
                                Err(err) => {
                                        let error_code = match err {
                                                msgs::DecodeError::UnknownVersion => 0x4000 | 1, // unknown realm byte
                                                msgs::DecodeError::UnknownRequiredFeature|
                                                msgs::DecodeError::InvalidValue|
                                                msgs::DecodeError::ShortRead => 0x4000 | 22, // invalid_onion_payload
                                                _ => 0x2000 | 2, // Should never happen
                                        };
                                        return_err!("Unable to decode our hop data", error_code, &[0;0]);
                                },
                                Ok(msg) => {
                                        let mut hmac = [0; 32];
                                        if let Err(_) = chacha_stream.read_exact(&mut hmac[..]) {
                                                return_err!("Unable to decode hop data", 0x4000 | 22, &[0;0]);
                                        }
                                        (msg, hmac)
                                },
                        }
                };

                let pending_forward_info = if next_hop_hmac == [0; 32] {
                                #[cfg(test)]
                                {
                                        // In tests, make sure that the initial onion pcket data is, at least, non-0.
                                        // We could do some fancy randomness test here, but, ehh, whatever.
                                        // This checks for the issue where you can calculate the path length given the
                                        // onion data as all the path entries that the originator sent will be here
                                        // as-is (and were originally 0s).
                                        // Of course reverse path calculation is still pretty easy given naive routing
                                        // algorithms, but this fixes the most-obvious case.
                                        let mut next_bytes = [0; 32];
                                        chacha_stream.read_exact(&mut next_bytes).unwrap();
                                        assert_ne!(next_bytes[..], [0; 32][..]);
                                        chacha_stream.read_exact(&mut next_bytes).unwrap();
                                        assert_ne!(next_bytes[..], [0; 32][..]);
                                }

                                // OUR PAYMENT!
                                // 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 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 rational).
                                if (msg.cltv_expiry as u64) <= self.latest_block_height.load(Ordering::Acquire) as u64 + HTLC_FAIL_BACK_BUFFER as u64 + 1 {
                                        return_err!("The final CLTV expiry is too soon to handle", 17, &[0;0]);
                                }
                                // final_incorrect_htlc_amount
                                if next_hop_data.amt_to_forward > msg.amount_msat {
                                        return_err!("Upstream node sent less than we were supposed to receive in payment", 19, &byte_utils::be64_to_array(msg.amount_msat));
                                }
                                // final_incorrect_cltv_expiry
                                if next_hop_data.outgoing_cltv_value != msg.cltv_expiry {
                                        return_err!("Upstream node set CLTV to the wrong value", 18, &byte_utils::be32_to_array(msg.cltv_expiry));
                                }

                                let payment_data = match next_hop_data.format {
                                        msgs::OnionHopDataFormat::Legacy { .. } => None,
                                        msgs::OnionHopDataFormat::NonFinalNode { .. } => return_err!("Got non final data with an HMAC of 0", 0x4000 | 22, &[0;0]),
                                        msgs::OnionHopDataFormat::FinalNode { payment_data } => payment_data,
                                };

                                // 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(PendingHTLCInfo {
                                        routing: PendingHTLCRouting::Receive {
                                                payment_data,
                                                incoming_cltv_expiry: msg.cltv_expiry,
                                        },
                                        payment_hash: msg.payment_hash.clone(),
                                        incoming_shared_secret: shared_secret,
                                        amt_to_forward: next_hop_data.amt_to_forward,
                                        outgoing_cltv_value: next_hop_data.outgoing_cltv_value,
                                })
                        } else {
                                let mut new_packet_data = [0; 20*65];
                                let read_pos = chacha_stream.read(&mut new_packet_data).unwrap();
                                #[cfg(debug_assertions)]
                                {
                                        // Check two things:
                                        // a) that the behavior of our stream here will return Ok(0) even if the TLV
                                        //    read above emptied out our buffer and the unwrap() wont needlessly panic
                                        // b) that we didn't somehow magically end up with extra data.
                                        let mut t = [0; 1];
                                        debug_assert!(chacha_stream.read(&mut t).unwrap() == 0);
                                }
                                // Once we've emptied the set of bytes our peer gave us, encrypt 0 bytes until we
                                // fill the onion hop data we'll forward to our next-hop peer.
                                chacha_stream.chacha.process_in_place(&mut new_packet_data[read_pos..]);

                                let mut new_pubkey = msg.onion_routing_packet.public_key.unwrap();

                                let blinding_factor = {
                                        let mut sha = Sha256::engine();
                                        sha.input(&new_pubkey.serialize()[..]);
                                        sha.input(&shared_secret);
                                        Sha256::from_engine(sha).into_inner()
                                };

                                let public_key = if let Err(e) = new_pubkey.mul_assign(&self.secp_ctx, &blinding_factor[..]) {
                                        Err(e)
                                } else { Ok(new_pubkey) };

                                let outgoing_packet = msgs::OnionPacket {
                                        version: 0,
                                        public_key,
                                        hop_data: new_packet_data,
                                        hmac: next_hop_hmac.clone(),
                                };

                                let short_channel_id = match next_hop_data.format {
                                        msgs::OnionHopDataFormat::Legacy { short_channel_id } => short_channel_id,
                                        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,
                                        amt_to_forward: next_hop_data.amt_to_forward,
                                        outgoing_cltv_value: next_hop_data.outgoing_cltv_value,
                                })
                        };

                channel_state = Some(self.channel_state.lock().unwrap());
                if let &PendingHTLCStatus::Forward(PendingHTLCInfo { ref routing, ref amt_to_forward, 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 {
                                let id_option = channel_state.as_ref().unwrap().short_to_id.get(&short_channel_id).cloned();
                                let forwarding_id = match id_option {
                                        None => { // unknown_next_peer
                                                return_err!("Don't have available channel for forwarding as requested.", 0x4000 | 10, &[0;0]);
                                        },
                                        Some(id) => id.clone(),
                                };
                                if let Some((err, code, chan_update)) = loop {
                                        let chan = channel_state.as_mut().unwrap().by_id.get_mut(&forwarding_id).unwrap();

                                        // 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, Some(self.get_channel_update(chan).unwrap())));
                                        }
                                        if *amt_to_forward < chan.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
                                                break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, Some(self.get_channel_update(chan).unwrap())));
                                        }
                                        let fee = amt_to_forward.checked_mul(chan.get_fee_proportional_millionths() as u64).and_then(|prop_fee| { (prop_fee / 1000000).checked_add(chan.get_holder_fee_base_msat(&self.fee_estimator) as u64) });
                                        if fee.is_none() || msg.amount_msat < fee.unwrap() || (msg.amount_msat - fee.unwrap()) < *amt_to_forward { // fee_insufficient
                                                break Some(("Prior hop has deviated from specified fees parameters or origin node has obsolete ones", 0x1000 | 12, Some(self.get_channel_update(chan).unwrap())));
                                        }
                                        if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + CLTV_EXPIRY_DELTA as u64 { // incorrect_cltv_expiry
                                                break Some(("Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta", 0x1000 | 13, Some(self.get_channel_update(chan).unwrap())));
                                        }
                                        let cur_height = self.latest_block_height.load(Ordering::Acquire) as u32 + 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 rational)
                                        if msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon
                                                break Some(("CLTV expiry is too close", 0x1000 | 14, Some(self.get_channel_update(chan).unwrap())));
                                        }
                                        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));
                                        }
                                        // In theory, we would be safe against unitentional channel-closure, if we only required a margin of LATENCY_GRACE_PERIOD_BLOCKS.
                                        // But, to be safe against policy reception, we use a longuer delay.
                                        if (*outgoing_cltv_value) as u64 <= (cur_height + HTLC_FAIL_BACK_BUFFER) as u64 {
                                                break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, Some(self.get_channel_update(chan).unwrap())));
                                        }

                                        break None;
                                }
                                {
                                        let mut res = Vec::with_capacity(8 + 128);
                                        if let Some(chan_update) = chan_update {
                                                if code == 0x1000 | 11 || code == 0x1000 | 12 {
                                                        res.extend_from_slice(&byte_utils::be64_to_array(msg.amount_msat));
                                                }
                                                else if code == 0x1000 | 13 {
                                                        res.extend_from_slice(&byte_utils::be32_to_array(msg.cltv_expiry));
                                                }
                                                else if code == 0x1000 | 20 {
                                                        // TODO: underspecified, follow https://github.com/lightningnetwork/lightning-rfc/issues/791
                                                        res.extend_from_slice(&byte_utils::be16_to_array(0));
                                                }
                                                res.extend_from_slice(&chan_update.encode_with_len()[..]);
                                        }
                                        return_err!(err, code, &res[..]);
                                }
                        }
                }

                (pending_forward_info, channel_state.unwrap())
        }

        /// only fails if the channel does not yet have an assigned short_id
        /// May be called with channel_state already locked!
        fn get_channel_update(&self, chan: &Channel<Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                let short_channel_id = match chan.get_short_channel_id() {
                        None => return Err(LightningError{err: "Channel not yet established".to_owned(), action: msgs::ErrorAction::IgnoreError}),
                        Some(id) => 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: CLTV_EXPIRY_DELTA,
                        htlc_minimum_msat: chan.get_counterparty_htlc_minimum_msat(),
                        htlc_maximum_msat: OptionalField::Present(chan.get_announced_htlc_max_msat()),
                        fee_base_msat: chan.get_holder_fee_base_msat(&self.fee_estimator),
                        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(&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_hash: &PaymentHash, payment_secret: &Option<PaymentSecret>, total_value: u64, cur_height: u32) -> 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(&self.keys_manager.get_secure_random_bytes()[..]).expect("RNG is busted");

                let onion_keys = onion_utils::construct_onion_keys(&self.secp_ctx, &path, &session_priv)
                        .map_err(|_| APIError::RouteError{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)?;
                if onion_utils::route_size_insane(&onion_payloads) {
                        return Err(APIError::RouteError{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::new(&self.total_consistency_lock, &self.persistence_notifier);

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

                        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::RouteError{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,
                                        }, onion_packet, &self.logger), channel_state, chan)
                                } {
                                        Some((update_add, commitment_signed, monitor_update)) => {
                                                if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                        maybe_break_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, true);
                                                        // Note that MonitorUpdateFailed here indicates (per function docs)
                                                        // that we will resend the commitment update once monitor updating
                                                        // is restored. 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 MonitorUpdateFailed, below.
                                                        return Err(APIError::MonitorUpdateFailed);
                                                }

                                                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 { unreachable!(); }
                        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.
        ///
        /// Note that if the payment_hash already exists elsewhere (eg you're sending a duplicative
        /// payment), we don't do anything to stop you! We always try to ensure that if the provided
        /// next hop knows the preimage to payment_hash they can claim an additional amount as
        /// specified in the last hop in the route! Thus, you should probably do your own
        /// payment_preimage tracking (which you should already be doing as they represent "proof of
        /// payment") and prevent double-sends yourself.
        ///
        /// May generate SendHTLCs message(s) event on success, which should be relayed.
        ///
        /// 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::RouteError 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::MonitorUpdateFailed 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.
        pub fn send_payment(&self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>) -> Result<(), PaymentSendFailure> {
                if route.paths.len() < 1 {
                        return Err(PaymentSendFailure::ParameterError(APIError::RouteError{err: "There must be at least one path to send over"}));
                }
                if route.paths.len() > 10 {
                        // This limit is completely arbitrary - there aren't any real fundamental path-count
                        // limits. After we support retrying individual paths we should likely bump this, but
                        // for now more than 10 paths likely carries too much one-path failure.
                        return Err(PaymentSendFailure::ParameterError(APIError::RouteError{err: "Sending over more than 10 paths is not currently supported"}));
                }
                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::RouteError{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::RouteError{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));
                }

                let cur_height = self.latest_block_height.load(Ordering::Acquire) as u32 + 1;
                let mut results = Vec::new();
                for path in route.paths.iter() {
                        results.push(self.send_payment_along_path(&path, &payment_hash, payment_secret, total_value, cur_height));
                }
                let mut has_ok = false;
                let mut has_err = false;
                for res in results.iter() {
                        if res.is_ok() { has_ok = true; }
                        if res.is_err() { has_err = true; }
                        if let &Err(APIError::MonitorUpdateFailed) = res {
                                // MonitorUpdateFailed is inherently unsafe to retry, so we call it a
                                // PartialFailure.
                                has_err = true;
                                has_ok = true;
                                break;
                        }
                }
                if has_err && has_ok {
                        Err(PaymentSendFailure::PartialFailure(results))
                } else if has_err {
                        Err(PaymentSendFailure::AllFailedRetrySafe(results.drain(..).map(|r| r.unwrap_err()).collect()))
                } else {
                        Ok(())
                }
        }

        /// Call this upon creation of a funding transaction for the given channel.
        ///
        /// Note that ALL inputs in the transaction pointed to by funding_txo MUST spend SegWit outputs
        /// or your counterparty can steal your funds!
        ///
        /// Panics if a funding transaction has already been provided for this channel.
        ///
        /// May panic if the funding_txo is duplicative with some other channel (note that this should
        /// be trivially prevented by using unique funding transaction keys per-channel).
        pub fn funding_transaction_generated(&self, temporary_channel_id: &[u8; 32], funding_txo: OutPoint) {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);

                let (chan, msg) = {
                        let (res, chan) = match self.channel_state.lock().unwrap().by_id.remove(temporary_channel_id) {
                                Some(mut chan) => {
                                        (chan.get_outbound_funding_created(funding_txo, &self.logger)
                                                .map_err(|e| if let ChannelError::Close(msg) = e {
                                                        MsgHandleErrInternal::from_finish_shutdown(msg, chan.channel_id(), chan.force_shutdown(true), None)
                                                } else { unreachable!(); })
                                        , chan)
                                },
                                None => return
                        };
                        match handle_error!(self, res, chan.get_counterparty_node_id()) {
                                Ok(funding_msg) => {
                                        (chan, funding_msg)
                                },
                                Err(_) => { return; }
                        }
                };

                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) => {
                                e.insert(chan);
                        }
                }
        }

        fn get_announcement_sigs(&self, chan: &Channel<Signer>) -> Option<msgs::AnnouncementSignatures> {
                if !chan.should_announce() {
                        log_trace!(self.logger, "Can't send announcement_signatures for private channel {}", log_bytes!(chan.channel_id()));
                        return None
                }

                let (announcement, our_bitcoin_sig) = match chan.get_channel_announcement(self.get_our_node_id(), self.genesis_hash.clone()) {
                        Ok(res) => res,
                        Err(_) => return None, // Only in case of state precondition violations eg channel is closing
                };
                let msghash = hash_to_message!(&Sha256dHash::hash(&announcement.encode()[..])[..]);
                let our_node_sig = self.secp_ctx.sign(&msghash, &self.our_network_key);

                Some(msgs::AnnouncementSignatures {
                        channel_id: chan.channel_id(),
                        short_channel_id: chan.get_short_channel_id().unwrap(),
                        node_signature: our_node_sig,
                        bitcoin_signature: our_bitcoin_sig,
                })
        }

        #[allow(dead_code)]
        // Messages of up to 64KB should never end up more than half full with addresses, as that would
        // be absurd. We ensure this by checking that at least 500 (our stated public contract on when
        // broadcast_node_announcement panics) of the maximum-length addresses would fit in a 64KB
        // message...
        const HALF_MESSAGE_IS_ADDRS: u32 = ::std::u16::MAX as u32 / (NetAddress::MAX_LEN as u32 + 1) / 2;
        #[deny(const_err)]
        #[allow(dead_code)]
        // ...by failing to compile if the number of addresses that would be half of a message is
        // smaller than 500:
        const STATIC_ASSERT: u32 = Self::HALF_MESSAGE_IS_ADDRS - 500;

        /// Generates a signed node_announcement from the given arguments and creates a
        /// BroadcastNodeAnnouncement event. Note that such messages will be ignored unless peers have
        /// seen a channel_announcement from us (ie unless we have public channels open).
        ///
        /// RGB is a node "color" and alias is a printable human-readable string to describe this node
        /// to humans. They carry no in-protocol meaning.
        ///
        /// addresses represent the set (possibly empty) of socket addresses on which this node accepts
        /// incoming connections. These will be broadcast to the network, publicly tying these
        /// addresses together. If you wish to preserve user privacy, addresses should likely contain
        /// only Tor Onion addresses.
        ///
        /// Panics if addresses is absurdly large (more than 500).
        pub fn broadcast_node_announcement(&self, rgb: [u8; 3], alias: [u8; 32], addresses: Vec<NetAddress>) {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);

                if addresses.len() > 500 {
                        panic!("More than half the message size was taken up by public addresses!");
                }

                let announcement = msgs::UnsignedNodeAnnouncement {
                        features: NodeFeatures::known(),
                        timestamp: self.last_node_announcement_serial.fetch_add(1, Ordering::AcqRel) as u32,
                        node_id: self.get_our_node_id(),
                        rgb, alias, addresses,
                        excess_address_data: Vec::new(),
                        excess_data: Vec::new(),
                };
                let msghash = hash_to_message!(&Sha256dHash::hash(&announcement.encode()[..])[..]);

                let mut channel_state = self.channel_state.lock().unwrap();
                channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastNodeAnnouncement {
                        msg: msgs::NodeAnnouncement {
                                signature: self.secp_ctx.sign(&msghash, &self.our_network_key),
                                contents: announcement
                        },
                });
        }

        /// 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::new(&self.total_consistency_lock, &self.persistence_notifier);

                let mut new_events = Vec::new();
                let mut failed_forwards = 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;

                        for (short_chan_id, mut pending_forwards) in channel_state.forward_htlcs.drain() {
                                if short_chan_id != 0 {
                                        let forward_chan_id = match channel_state.short_to_id.get(&short_chan_id) {
                                                Some(chan_id) => chan_id.clone(),
                                                None => {
                                                        failed_forwards.reserve(pending_forwards.len());
                                                        for forward_info in pending_forwards.drain(..) {
                                                                match forward_info {
                                                                        HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_htlc_id, forward_info,
                                                                                                   prev_funding_outpoint } => {
                                                                                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,
                                                                                });
                                                                                failed_forwards.push((htlc_source, forward_info.payment_hash,
                                                                                        HTLCFailReason::Reason { failure_code: 0x4000 | 10, data: Vec::new() }
                                                                                ));
                                                                        },
                                                                        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.
                                                                        }
                                                                }
                                                        }
                                                        continue;
                                                }
                                        };
                                        if let hash_map::Entry::Occupied(mut chan) = channel_state.by_id.entry(forward_chan_id) {
                                                let mut add_htlc_msgs = Vec::new();
                                                let mut fail_htlc_msgs = Vec::new();
                                                for forward_info in pending_forwards.drain(..) {
                                                        match forward_info {
                                                                HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_htlc_id, forward_info: PendingHTLCInfo {
                                                                                routing: PendingHTLCRouting::Forward {
                                                                                        onion_packet, ..
                                                                                }, incoming_shared_secret, payment_hash, amt_to_forward, outgoing_cltv_value },
                                                                                prev_funding_outpoint } => {
                                                                        log_trace!(self.logger, "Adding HTLC from short id {} with payment_hash {} to channel with short id {} after delay", log_bytes!(payment_hash.0), prev_short_channel_id, 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,
                                                                        });
                                                                        match chan.get_mut().send_htlc(amt_to_forward, payment_hash, outgoing_cltv_value, htlc_source.clone(), onion_packet) {
                                                                                Err(e) => {
                                                                                        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 chan_update = self.get_channel_update(chan.get()).unwrap();
                                                                                        failed_forwards.push((htlc_source, payment_hash,
                                                                                                HTLCFailReason::Reason { failure_code: 0x1000 | 7, data: chan_update.encode_with_len() }
                                                                                        ));
                                                                                        continue;
                                                                                },
                                                                                Ok(update_add) => {
                                                                                        match update_add {
                                                                                                Some(msg) => { add_htlc_msgs.push(msg); },
                                                                                                None => {
                                                                                                        // Nothing to do here...we're waiting on a remote
                                                                                                        // revoke_and_ack before we can add anymore HTLCs. The Channel
                                                                                                        // will automatically handle building the update_add_htlc and
                                                                                                        // commitment_signed messages when we can.
                                                                                                        // TODO: Do some kind of timer to set the channel as !is_live()
                                                                                                        // as we don't really want others relying on us relaying through
                                                                                                        // this channel currently :/.
                                                                                                }
                                                                                        }
                                                                                }
                                                                        }
                                                                },
                                                                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 {} after delay", short_chan_id);
                                                                        match chan.get_mut().get_update_fail_htlc(htlc_id, err_packet) {
                                                                                Err(e) => {
                                                                                        if let ChannelError::Ignore(msg) = e {
                                                                                                log_trace!(self.logger, "Failed to fail backwards to short_id {}: {}", short_chan_id, msg);
                                                                                        } else {
                                                                                                panic!("Stated return value requirements in get_update_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;
                                                                                },
                                                                                Ok(Some(msg)) => { fail_htlc_msgs.push(msg); },
                                                                                Ok(None) => {
                                                                                        // Nothing to do here...we're waiting on a remote
                                                                                        // revoke_and_ack before we can update the commitment
                                                                                        // transaction. The Channel will automatically handle
                                                                                        // building the update_fail_htlc and commitment_signed
                                                                                        // messages when we can.
                                                                                        // We don't need any kind of timer here as they should fail
                                                                                        // the channel onto the chain if they can't get our
                                                                                        // update_fail_htlc in time, it's not our problem.
                                                                                }
                                                                        }
                                                                },
                                                        }
                                                }

                                                if !add_htlc_msgs.is_empty() || !fail_htlc_msgs.is_empty() {
                                                        let (commitment_msg, monitor_update) = match chan.get_mut().send_commitment(&self.logger) {
                                                                Ok(res) => res,
                                                                Err(e) => {
                                                                        // We surely failed send_commitment due to bad keys, in that case
                                                                        // close channel and then send error message to peer.
                                                                        let counterparty_node_id = chan.get().get_counterparty_node_id();
                                                                        let err: Result<(), _>  = match e {
                                                                                ChannelError::Ignore(_) => {
                                                                                        panic!("Stated return value requirements in send_commitment() were not met");
                                                                                },
                                                                                ChannelError::Close(msg) => {
                                                                                        log_trace!(self.logger, "Closing channel {} due to Close-required error: {}", log_bytes!(chan.key()[..]), msg);
                                                                                        let (channel_id, mut channel) = chan.remove_entry();
                                                                                        if let Some(short_id) = channel.get_short_channel_id() {
                                                                                                channel_state.short_to_id.remove(&short_id);
                                                                                        }
                                                                                        Err(MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, channel.force_shutdown(true), self.get_channel_update(&channel).ok()))
                                                                                },
                                                                                ChannelError::CloseDelayBroadcast(_) => { panic!("Wait is only generated on receipt of channel_reestablish, which is handled by try_chan_entry, we don't bother to support it here"); }
                                                                        };
                                                                        handle_errors.push((counterparty_node_id, err));
                                                                        continue;
                                                                }
                                                        };
                                                        if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                                handle_errors.push((chan.get().get_counterparty_node_id(), handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, true)));
                                                                continue;
                                                        }
                                                        channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                                node_id: chan.get().get_counterparty_node_id(),
                                                                updates: msgs::CommitmentUpdate {
                                                                        update_add_htlcs: add_htlc_msgs,
                                                                        update_fulfill_htlcs: Vec::new(),
                                                                        update_fail_htlcs: fail_htlc_msgs,
                                                                        update_fail_malformed_htlcs: Vec::new(),
                                                                        update_fee: None,
                                                                        commitment_signed: commitment_msg,
                                                                },
                                                        });
                                                }
                                        } else {
                                                unreachable!();
                                        }
                                } else {
                                        for forward_info in pending_forwards.drain(..) {
                                                match forward_info {
                                                        HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_htlc_id, forward_info: PendingHTLCInfo {
                                                                        routing: PendingHTLCRouting::Receive { payment_data, incoming_cltv_expiry },
                                                                        incoming_shared_secret, payment_hash, amt_to_forward, .. },
                                                                        prev_funding_outpoint } => {
                                                                let 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,
                                                                };

                                                                let mut total_value = 0;
                                                                let payment_secret_opt =
                                                                        if let &Some(ref data) = &payment_data { Some(data.payment_secret.clone()) } else { None };
                                                                let htlcs = channel_state.claimable_htlcs.entry((payment_hash, payment_secret_opt))
                                                                        .or_insert(Vec::new());
                                                                htlcs.push(ClaimableHTLC {
                                                                        prev_hop,
                                                                        value: amt_to_forward,
                                                                        payment_data: payment_data.clone(),
                                                                        cltv_expiry: incoming_cltv_expiry,
                                                                });
                                                                if let &Some(ref data) = &payment_data {
                                                                        for htlc in htlcs.iter() {
                                                                                total_value += htlc.value;
                                                                                if htlc.payment_data.as_ref().unwrap().total_msat != data.total_msat {
                                                                                        total_value = msgs::MAX_VALUE_MSAT;
                                                                                }
                                                                                if total_value >= msgs::MAX_VALUE_MSAT { break; }
                                                                        }
                                                                        if total_value >= msgs::MAX_VALUE_MSAT || total_value > data.total_msat  {
                                                                                for htlc in htlcs.iter() {
                                                                                        let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec();
                                                                                        htlc_msat_height_data.extend_from_slice(
                                                                                                &byte_utils::be32_to_array(
                                                                                                        self.latest_block_height.load(Ordering::Acquire)
                                                                                                                as u32,
                                                                                                ),
                                                                                        );
                                                                                        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,
                                                                                                }), payment_hash,
                                                                                                HTLCFailReason::Reason { failure_code: 0x4000 | 15, data: htlc_msat_height_data }
                                                                                        ));
                                                                                }
                                                                        } else if total_value == data.total_msat {
                                                                                new_events.push(events::Event::PaymentReceived {
                                                                                        payment_hash,
                                                                                        payment_secret: Some(data.payment_secret),
                                                                                        amt: total_value,
                                                                                });
                                                                        }
                                                                } else {
                                                                        new_events.push(events::Event::PaymentReceived {
                                                                                payment_hash,
                                                                                payment_secret: None,
                                                                                amt: amt_to_forward,
                                                                        });
                                                                }
                                                        },
                                                        HTLCForwardInfo::AddHTLC { .. } => {
                                                                panic!("short_channel_id == 0 should imply any pending_forward entries are of type Receive");
                                                        },
                                                        HTLCForwardInfo::FailHTLC { .. } => {
                                                                panic!("Got pending fail of our own HTLC");
                                                        }
                                                }
                                        }
                                }
                        }
                }

                for (htlc_source, payment_hash, failure_reason) in failed_forwards.drain(..) {
                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source, &payment_hash, failure_reason);
                }

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

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

        #[cfg(any(test, feature = "_test_utils"))]
        pub(crate) fn test_process_background_events(&self) {
                self.process_background_events();
        }

        /// If a peer is disconnected we mark any channels with that peer as 'disabled'.
        /// After some time, if channels are still disabled we need to broadcast a ChannelUpdate
        /// to inform the network about the uselessness of these channels.
        ///
        /// This method handles all the details, and must be called roughly once per minute.
        ///
        /// Note that in some rare cases this may generate a `chain::Watch::update_channel` call.
        pub fn timer_chan_freshness_every_min(&self) {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                self.process_background_events();

                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                for (_, chan) in channel_state.by_id.iter_mut() {
                        if chan.is_disabled_staged() && !chan.is_live() {
                                if let Ok(update) = self.get_channel_update(&chan) {
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                msg: update
                                        });
                                }
                                chan.to_fresh();
                        } else if chan.is_disabled_staged() && chan.is_live() {
                                chan.to_fresh();
                        } else if chan.is_disabled_marked() {
                                chan.to_disabled_staged();
                        }
                }
        }

        /// Indicates that the preimage for payment_hash is unknown or the received amount is incorrect
        /// after a PaymentReceived event, failing the HTLC back to its origin and freeing resources
        /// along the path (including in our own channel on which we received it).
        /// Returns false if no payment was found to fail backwards, true if the process of failing the
        /// HTLC backwards has been started.
        pub fn fail_htlc_backwards(&self, payment_hash: &PaymentHash, payment_secret: &Option<PaymentSecret>) -> bool {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);

                let mut channel_state = Some(self.channel_state.lock().unwrap());
                let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(&(*payment_hash, *payment_secret));
                if let Some(mut sources) = removed_source {
                        for htlc in sources.drain(..) {
                                if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap()); }
                                let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec();
                                htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array(
                                        self.latest_block_height.load(Ordering::Acquire) as u32,
                                ));
                                self.fail_htlc_backwards_internal(channel_state.take().unwrap(),
                                                HTLCSource::PreviousHopData(htlc.prev_hop), payment_hash,
                                                HTLCFailReason::Reason { failure_code: 0x4000 | 15, data: htlc_msat_height_data });
                        }
                        true
                } else { false }
        }

        // 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]) {
                for (htlc_src, payment_hash) in htlcs_to_fail.drain(..) {
                        match htlc_src {
                                HTLCSource::PreviousHopData(HTLCPreviousHopData { .. }) => {
                                        let (failure_code, onion_failure_data) =
                                                match self.channel_state.lock().unwrap().by_id.entry(channel_id) {
                                                        hash_map::Entry::Occupied(chan_entry) => {
                                                                if let Ok(upd) = self.get_channel_update(&chan_entry.get()) {
                                                                        (0x1000|7, upd.encode_with_len())
                                                                } else {
                                                                        (0x4000|10, Vec::new())
                                                                }
                                                        },
                                                        hash_map::Entry::Vacant(_) => (0x4000|10, Vec::new())
                                                };
                                        let channel_state = self.channel_state.lock().unwrap();
                                        self.fail_htlc_backwards_internal(channel_state,
                                                htlc_src, &payment_hash, HTLCFailReason::Reason { failure_code, data: onion_failure_data});
                                },
                                HTLCSource::OutboundRoute { .. } => {
                                        self.pending_events.lock().unwrap().push(
                                                events::Event::PaymentFailed {
                                                        payment_hash,
                                                        rejected_by_dest: false,
#[cfg(test)]
                                                        error_code: None,
#[cfg(test)]
                                                        error_data: None,
                                                }
                                        )
                                },
                        };
                }
        }

        /// Fails an HTLC backwards to the sender of it to us.
        /// Note that while we take a channel_state lock as input, we do *not* assume consistency here.
        /// There are several callsites that do stupid things like loop over a list of payment_hashes
        /// to fail and take the channel_state lock for each iteration (as we take ownership and may
        /// drop it). In other words, no assumptions are made that entries in claimable_htlcs point to
        /// still-available channels.
        fn fail_htlc_backwards_internal(&self, mut channel_state_lock: MutexGuard<ChannelHolder<Signer>>, source: HTLCSource, payment_hash: &PaymentHash, onion_error: HTLCFailReason) {
                //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, .. } => {
                                log_trace!(self.logger, "Failing outbound payment HTLC with payment_hash {}", log_bytes!(payment_hash.0));
                                mem::drop(channel_state_lock);
                                match &onion_error {
                                        &HTLCFailReason::LightningError { ref err } => {
#[cfg(test)]
                                                let (channel_update, payment_retryable, onion_error_code, onion_error_data) = onion_utils::process_onion_failure(&self.secp_ctx, &self.logger, &source, err.data.clone());
#[cfg(not(test))]
                                                let (channel_update, payment_retryable, _, _) = onion_utils::process_onion_failure(&self.secp_ctx, &self.logger, &source, err.data.clone());
                                                // 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(update) = channel_update {
                                                        self.channel_state.lock().unwrap().pending_msg_events.push(
                                                                events::MessageSendEvent::PaymentFailureNetworkUpdate {
                                                                        update,
                                                                }
                                                        );
                                                }
                                                self.pending_events.lock().unwrap().push(
                                                        events::Event::PaymentFailed {
                                                                payment_hash: payment_hash.clone(),
                                                                rejected_by_dest: !payment_retryable,
#[cfg(test)]
                                                                error_code: onion_error_code,
#[cfg(test)]
                                                                error_data: onion_error_data
                                                        }
                                                );
                                        },
                                        &HTLCFailReason::Reason {
#[cfg(test)]
                                                        ref failure_code,
#[cfg(test)]
                                                        ref data,
                                                        .. } => {
                                                // we get a fail_malformed_htlc from the first hop
                                                // TODO: We'd like to generate a PaymentFailureNetworkUpdate for temporary
                                                // failures here, but that would be insufficient as get_route
                                                // generally ignores its view of our own channels as we provide them via
                                                // ChannelDetails.
                                                // TODO: For non-temporary failures, we really should be closing the
                                                // channel here as we apparently can't relay through them anyway.
                                                self.pending_events.lock().unwrap().push(
                                                        events::Event::PaymentFailed {
                                                                payment_hash: payment_hash.clone(),
                                                                rejected_by_dest: path.len() == 1,
#[cfg(test)]
                                                                error_code: Some(*failure_code),
#[cfg(test)]
                                                                error_data: Some(data.clone()),
                                                        }
                                                );
                                        }
                                }
                        },
                        HTLCSource::PreviousHopData(HTLCPreviousHopData { short_channel_id, htlc_id, incoming_packet_shared_secret, .. }) => {
                                let err_packet = match onion_error {
                                        HTLCFailReason::Reason { failure_code, data } => {
                                                log_trace!(self.logger, "Failing HTLC with payment_hash {} backwards from us with code {}", log_bytes!(payment_hash.0), failure_code);
                                                let packet = onion_utils::build_failure_packet(&incoming_packet_shared_secret, failure_code, &data[..]).encode();
                                                onion_utils::encrypt_failure_packet(&incoming_packet_shared_secret, &packet)
                                        },
                                        HTLCFailReason::LightningError { err } => {
                                                log_trace!(self.logger, "Failing HTLC with payment_hash {} backwards with pre-built LightningError", log_bytes!(payment_hash.0));
                                                onion_utils::encrypt_failure_packet(&incoming_packet_shared_secret, &err.data)
                                        }
                                };

                                let mut forward_event = None;
                                if channel_state_lock.forward_htlcs.is_empty() {
                                        forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS));
                                }
                                match channel_state_lock.forward_htlcs.entry(short_channel_id) {
                                        hash_map::Entry::Occupied(mut entry) => {
                                                entry.get_mut().push(HTLCForwardInfo::FailHTLC { htlc_id, err_packet });
                                        },
                                        hash_map::Entry::Vacant(entry) => {
                                                entry.insert(vec!(HTLCForwardInfo::FailHTLC { htlc_id, err_packet }));
                                        }
                                }
                                mem::drop(channel_state_lock);
                                if let Some(time) = forward_event {
                                        let mut pending_events = self.pending_events.lock().unwrap();
                                        pending_events.push(events::Event::PendingHTLCsForwardable {
                                                time_forwardable: time
                                        });
                                }
                        },
                }
        }

        /// Provides a payment preimage in response to a PaymentReceived event, returning true and
        /// generating message events for the net layer to claim the payment, if possible. Thus, you
        /// should probably kick the net layer to go send messages if this returns true!
        ///
        /// You must specify the expected amounts for this HTLC, and we will only claim HTLCs
        /// available within a few percent of the expected amount. This is critical for several
        /// reasons : a) it avoids providing senders with `proof-of-payment` (in the form of the
        /// payment_preimage without having provided the full value and b) it avoids certain
        /// privacy-breaking recipient-probing attacks which may reveal payment activity to
        /// motivated attackers.
        ///
        /// Note that the privacy concerns in (b) are not relevant in payments with a payment_secret
        /// set. Thus, for such payments we will claim any payments which do not under-pay.
        ///
        /// May panic if called except in response to a PaymentReceived event.
        pub fn claim_funds(&self, payment_preimage: PaymentPreimage, payment_secret: &Option<PaymentSecret>, expected_amount: u64) -> bool {
                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());

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

                let mut channel_state = Some(self.channel_state.lock().unwrap());
                let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(&(payment_hash, *payment_secret));
                if let Some(mut sources) = removed_source {
                        assert!(!sources.is_empty());

                        // If we are claiming an MPP payment, we have to take special care to ensure that each
                        // channel exists before claiming all of the payments (inside one lock).
                        // Note that channel existance is sufficient as we should always get a monitor update
                        // which will take care of the real HTLC claim enforcement.
                        //
                        // 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 (is_mpp, mut valid_mpp) = if let &Some(ref data) = &sources[0].payment_data {
                                assert!(payment_secret.is_some());
                                (true, data.total_msat >= expected_amount)
                        } else {
                                assert!(payment_secret.is_none());
                                (false, false)
                        };

                        for htlc in sources.iter() {
                                if !is_mpp || !valid_mpp { break; }
                                if let None = channel_state.as_ref().unwrap().short_to_id.get(&htlc.prev_hop.short_channel_id) {
                                        valid_mpp = false;
                                }
                        }

                        let mut errs = Vec::new();
                        let mut claimed_any_htlcs = false;
                        for htlc in sources.drain(..) {
                                if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap()); }
                                if (is_mpp && !valid_mpp) || (!is_mpp && (htlc.value < expected_amount || htlc.value > expected_amount * 2)) {
                                        let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec();
                                        htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array(
                                                self.latest_block_height.load(Ordering::Acquire) as u32,
                                        ));
                                        self.fail_htlc_backwards_internal(channel_state.take().unwrap(),
                                                                         HTLCSource::PreviousHopData(htlc.prev_hop), &payment_hash,
                                                                         HTLCFailReason::Reason { failure_code: 0x4000|15, data: htlc_msat_height_data });
                                } else {
                                        match self.claim_funds_from_hop(channel_state.as_mut().unwrap(), htlc.prev_hop, payment_preimage) {
                                                Err(Some(e)) => {
                                                        if let msgs::ErrorAction::IgnoreError = e.1.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: {}", e.1.err.err);
                                                                claimed_any_htlcs = true;
                                                        } else { errs.push(e); }
                                                },
                                                Err(None) if is_mpp => unreachable!("We already checked for channel existence, we can't fail here!"),
                                                Err(None) => {
                                                        log_warn!(self.logger, "Channel we expected to claim an HTLC from was closed.");
                                                },
                                                Ok(()) => claimed_any_htlcs = true,
                                        }
                                }
                        }

                        // Now that we've done the entire above loop in one lock, we can handle any errors
                        // which were generated.
                        channel_state.take();

                        for (counterparty_node_id, err) in errs.drain(..) {
                                let res: Result<(), _> = Err(err);
                                let _ = handle_error!(self, res, counterparty_node_id);
                        }

                        claimed_any_htlcs
                } else { false }
        }

        fn claim_funds_from_hop(&self, channel_state_lock: &mut MutexGuard<ChannelHolder<Signer>>, prev_hop: HTLCPreviousHopData, payment_preimage: PaymentPreimage) -> Result<(), Option<(PublicKey, MsgHandleErrInternal)>> {
                //TODO: Delay the claimed_funds relaying just like we do outbound relay!
                let channel_state = &mut **channel_state_lock;
                let chan_id = match channel_state.short_to_id.get(&prev_hop.short_channel_id) {
                        Some(chan_id) => chan_id.clone(),
                        None => {
                                return Err(None)
                        }
                };

                if let hash_map::Entry::Occupied(mut chan) = channel_state.by_id.entry(chan_id) {
                        let was_frozen_for_monitor = chan.get().is_awaiting_monitor_update();
                        match chan.get_mut().get_update_fulfill_htlc_and_commit(prev_hop.htlc_id, payment_preimage, &self.logger) {
                                Ok((msgs, monitor_option)) => {
                                        if let Some(monitor_update) = monitor_option {
                                                if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                        if was_frozen_for_monitor {
                                                                assert!(msgs.is_none());
                                                        } else {
                                                                return Err(Some((chan.get().get_counterparty_node_id(), handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, msgs.is_some()).unwrap_err())));
                                                        }
                                                }
                                        }
                                        if let Some((msg, commitment_signed)) = msgs {
                                                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,
                                                        }
                                                });
                                        }
                                        return Ok(())
                                },
                                Err(e) => {
                                        // TODO: Do something with e?
                                        // This should only occur if we are claiming an HTLC at the same time as the
                                        // HTLC is being failed (eg because a block is being connected and this caused
                                        // an HTLC to time out). This should, of course, only occur if the user is the
                                        // one doing the claiming (as it being a part of a peer claim would imply we're
                                        // about to lose funds) and only if the lock in claim_funds was dropped as a
                                        // previous HTLC was failed (thus not for an MPP payment).
                                        debug_assert!(false, "This shouldn't be reachable except in absurdly rare cases between monitor updates and HTLC timeouts: {:?}", e);
                                        return Err(None)
                                },
                        }
                } else { unreachable!(); }
        }

        fn claim_funds_internal(&self, mut channel_state_lock: MutexGuard<ChannelHolder<Signer>>, source: HTLCSource, payment_preimage: PaymentPreimage) {
                match source {
                        HTLCSource::OutboundRoute { .. } => {
                                mem::drop(channel_state_lock);
                                let mut pending_events = self.pending_events.lock().unwrap();
                                pending_events.push(events::Event::PaymentSent {
                                        payment_preimage
                                });
                        },
                        HTLCSource::PreviousHopData(hop_data) => {
                                let prev_outpoint = hop_data.outpoint;
                                if let Err((counterparty_node_id, err)) = match self.claim_funds_from_hop(&mut channel_state_lock, hop_data, payment_preimage) {
                                        Ok(()) => Ok(()),
                                        Err(None) => {
                                                let preimage_update = ChannelMonitorUpdate {
                                                        update_id: CLOSED_CHANNEL_UPDATE_ID,
                                                        updates: vec![ChannelMonitorUpdateStep::PaymentPreimage {
                                                                payment_preimage: payment_preimage.clone(),
                                                        }],
                                                };
                                                // We update the ChannelMonitor on the backward link, after
                                                // receiving an offchain preimage event from the forward link (the
                                                // event being update_fulfill_htlc).
                                                if let Err(e) = self.chain_monitor.update_channel(prev_outpoint, preimage_update) {
                                                        log_error!(self.logger, "Critical error: failed to update channel monitor with preimage {:?}: {:?}",
                                                                   payment_preimage, e);
                                                }
                                                Ok(())
                                        },
                                        Err(Some(res)) => Err(res),
                                } {
                                        mem::drop(channel_state_lock);
                                        let res: Result<(), _> = Err(err);
                                        let _ = handle_error!(self, res, counterparty_node_id);
                                }
                        },
                }
        }

        /// Gets the node_id held by this ChannelManager
        pub fn get_our_node_id(&self) -> PublicKey {
                PublicKey::from_secret_key(&self.secp_ctx, &self.our_network_key)
        }

        /// Restores a single, given channel to normal operation after a
        /// ChannelMonitorUpdateErr::TemporaryFailure was returned from a channel monitor update
        /// operation.
        ///
        /// All ChannelMonitor updates up to and including highest_applied_update_id must have been
        /// fully committed in every copy of the given channels' ChannelMonitors.
        ///
        /// Note that there is no effect to calling with a highest_applied_update_id other than the
        /// current latest ChannelMonitorUpdate and one call to this function after multiple
        /// ChannelMonitorUpdateErr::TemporaryFailures is fine. The highest_applied_update_id field
        /// exists largely only to prevent races between this and concurrent update_monitor calls.
        ///
        /// Thus, the anticipated use is, at a high level:
        ///  1) You register a chain::Watch with this ChannelManager,
        ///  2) it stores each update to disk, and begins updating any remote (eg watchtower) copies of
        ///     said ChannelMonitors as it can, returning ChannelMonitorUpdateErr::TemporaryFailures
        ///     any time it cannot do so instantly,
        ///  3) update(s) are applied to each remote copy of a ChannelMonitor,
        ///  4) once all remote copies are updated, you call this function with the update_id that
        ///     completed, and once it is the latest the Channel will be re-enabled.
        pub fn channel_monitor_updated(&self, funding_txo: &OutPoint, highest_applied_update_id: u64) {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);

                let mut close_results = Vec::new();
                let mut htlc_forwards = Vec::new();
                let mut htlc_failures = Vec::new();
                let mut pending_events = Vec::new();

                {
                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        let short_to_id = &mut channel_state.short_to_id;
                        let pending_msg_events = &mut channel_state.pending_msg_events;
                        let channel = match channel_state.by_id.get_mut(&funding_txo.to_channel_id()) {
                                Some(chan) => chan,
                                None => return,
                        };
                        if !channel.is_awaiting_monitor_update() || channel.get_latest_monitor_update_id() != highest_applied_update_id {
                                return;
                        }

                        let (raa, commitment_update, order, pending_forwards, mut pending_failures, needs_broadcast_safe, funding_locked) = channel.monitor_updating_restored(&self.logger);
                        if !pending_forwards.is_empty() {
                                htlc_forwards.push((channel.get_short_channel_id().expect("We can't have pending forwards before funding confirmation"), funding_txo.clone(), pending_forwards));
                        }
                        htlc_failures.append(&mut pending_failures);

                        macro_rules! handle_cs { () => {
                                if let Some(update) = commitment_update {
                                        pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                node_id: channel.get_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: channel.get_counterparty_node_id(),
                                                msg: revoke_and_ack,
                                        });
                                }
                        } }
                        match order {
                                RAACommitmentOrder::CommitmentFirst => {
                                        handle_cs!();
                                        handle_raa!();
                                },
                                RAACommitmentOrder::RevokeAndACKFirst => {
                                        handle_raa!();
                                        handle_cs!();
                                },
                        }
                        if needs_broadcast_safe {
                                pending_events.push(events::Event::FundingBroadcastSafe {
                                        funding_txo: channel.get_funding_txo().unwrap(),
                                        user_channel_id: channel.get_user_id(),
                                });
                        }
                        if let Some(msg) = funding_locked {
                                pending_msg_events.push(events::MessageSendEvent::SendFundingLocked {
                                        node_id: channel.get_counterparty_node_id(),
                                        msg,
                                });
                                if let Some(announcement_sigs) = self.get_announcement_sigs(channel) {
                                        pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                node_id: channel.get_counterparty_node_id(),
                                                msg: announcement_sigs,
                                        });
                                }
                                short_to_id.insert(channel.get_short_channel_id().unwrap(), channel.channel_id());
                        }
                }

                self.pending_events.lock().unwrap().append(&mut pending_events);

                for failure in htlc_failures.drain(..) {
                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), failure.0, &failure.1, failure.2);
                }
                self.forward_htlcs(&mut htlc_forwards[..]);

                for res in close_results.drain(..) {
                        self.finish_force_close_channel(res);
                }
        }

        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()));
                }

                let channel = Channel::new_from_req(&self.fee_estimator, &self.keys_manager, counterparty_node_id.clone(), their_features, msg, 0, &self.default_configuration)
                        .map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.temporary_channel_id))?;
                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(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("temporary_channel_id collision!".to_owned(), msg.temporary_channel_id.clone())),
                        hash_map::Entry::Vacant(entry) => {
                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
                                        node_id: counterparty_node_id.clone(),
                                        msg: channel.get_accept_channel(),
                                });
                                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, their_features), channel_state, 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,
                        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 chan) = {
                        let last_block_hash = *self.last_block_hash.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, last_block_hash, &self.logger), channel_state, 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
                if let Err(e) = self.chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor) {
                        match e {
                                ChannelMonitorUpdateErr::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 do a force-close here as that would generate a monitor update 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(true);
                                        assert!(failed_htlcs.is_empty());
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("ChannelMonitor storage failure".to_owned(), funding_msg.channel_id));
                                },
                                ChannelMonitorUpdateErr::TemporaryFailure => {
                                        // 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 funding_locked
                                        // until we have persisted our monitor.
                                        chan.monitor_update_failed(false, false, Vec::new(), Vec::new());
                                },
                        }
                }
                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) => {
                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendFundingSigned {
                                        node_id: counterparty_node_id.clone(),
                                        msg: funding_msg,
                                });
                                e.insert(chan);
                        }
                }
                Ok(())
        }

        fn internal_funding_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingSigned) -> Result<(), MsgHandleErrInternal> {
                let (funding_txo, user_id) = {
                        let last_block_hash = *self.last_block_hash.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 = match chan.get_mut().funding_signed(&msg, last_block_hash, &self.logger) {
                                                Ok(update) => update,
                                                Err(e) => try_chan_entry!(self, Err(e), channel_state, chan),
                                        };
                                        if let Err(e) = self.chain_monitor.watch_channel(chan.get().get_funding_txo().unwrap(), monitor) {
                                                return_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::RevokeAndACKFirst, false, false);
                                        }
                                        (chan.get().get_funding_txo().unwrap(), 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.channel_id))
                        }
                };
                let mut pending_events = self.pending_events.lock().unwrap();
                pending_events.push(events::Event::FundingBroadcastSafe {
                        funding_txo,
                        user_channel_id: user_id,
                });
                Ok(())
        }

        fn internal_funding_locked(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingLocked) -> 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));
                                }
                                try_chan_entry!(self, chan.get_mut().funding_locked(&msg), channel_state, chan);
                                if let Some(announcement_sigs) = self.get_announcement_sigs(chan.get()) {
                                        log_trace!(self.logger, "Sending announcement_signatures for {} in response to funding_locked", log_bytes!(chan.get().channel_id()));
                                        // If we see locking block before receiving remote funding_locked, we broadcast our
                                        // announcement_sigs at remote funding_locked reception. If we receive remote
                                        // funding_locked before seeing locking block, we broadcast our announcement_sigs at locking
                                        // block connection. We should guanrantee to broadcast announcement_sigs to our peer whatever
                                        // the order of the events but our peer may not receive it due to disconnection. The specs
                                        // lacking an acknowledgement for announcement_sigs we may have to re-send them at peer
                                        // connection in the future if simultaneous misses by both peers due to network/hardware
                                        // failures is an issue. Note, to achieve its goal, only one of the announcement_sigs needs
                                        // to be received, from then sigs are going to be flood to the whole network.
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                node_id: counterparty_node_id.clone(),
                                                msg: announcement_sigs,
                                        });
                                }
                                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, 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 (shutdown, closing_signed, dropped_htlcs) = try_chan_entry!(self, chan_entry.get_mut().shutdown(&self.fee_estimator, &their_features, &msg), channel_state, chan_entry);
                                        if let Some(msg) = shutdown {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                        node_id: counterparty_node_id.clone(),
                                                        msg,
                                                });
                                        }
                                        if let Some(msg) = closing_signed {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendClosingSigned {
                                                        node_id: counterparty_node_id.clone(),
                                                        msg,
                                                });
                                        }
                                        if chan_entry.get().is_shutdown() {
                                                if let Some(short_id) = chan_entry.get().get_short_channel_id() {
                                                        channel_state.short_to_id.remove(&short_id);
                                                }
                                                (dropped_htlcs, Some(chan_entry.remove_entry().1))
                                        } else { (dropped_htlcs, None) }
                                },
                                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(..) {
                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() });
                }
                if let Some(chan) = chan_option {
                        if let Ok(update) = self.get_channel_update(&chan) {
                                let mut channel_state = self.channel_state.lock().unwrap();
                                channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                        msg: update
                                });
                        }
                }
                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), channel_state, 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)!
                                                if let Some(short_id) = chan_entry.get().get_short_channel_id() {
                                                        channel_state.short_to_id.remove(&short_id);
                                                }
                                                (tx, Some(chan_entry.remove_entry().1))
                                        } 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_trace!(self.logger, "Broadcast onchain {}", 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(&chan) {
                                let mut channel_state = self.channel_state.lock().unwrap();
                                channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                        msg: update
                                });
                        }
                }
                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, mut channel_state_lock) = self.decode_update_add_htlc_onion(msg);
                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<Signer>, pending_forward_info: PendingHTLCStatus, error_code: u16| {
                                        // Ensure error_code has the UPDATE flag set, since by default we send a
                                        // channel update along as part of failing the HTLC.
                                        assert!((error_code & 0x1000) != 0);
                                        // 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 let Ok(upd) = self.get_channel_update(chan) {
                                                                onion_utils::build_first_hop_failure_packet(incoming_shared_secret, error_code, &{
                                                                        let mut res = Vec::with_capacity(8 + 128);
                                                                        // TODO: underspecified, follow https://github.com/lightningnetwork/lightning-rfc/issues/791
                                                                        res.extend_from_slice(&byte_utils::be16_to_array(0));
                                                                        res.extend_from_slice(&upd.encode_with_len()[..]);
                                                                        res
                                                                }[..])
                                                        } else {
                                                                // The only case where we'd be unable to
                                                                // successfully get a channel update is if the
                                                                // channel isn't in the fully-funded state yet,
                                                                // implying our counterparty is trying to route
                                                                // payments over the channel back to themselves
                                                                // (cause no one else should know the short_id
                                                                // is a lightning channel yet). We should have
                                                                // no problem just calling this
                                                                // unknown_next_peer (0x4000|10).
                                                                onion_utils::build_first_hop_failure_packet(incoming_shared_secret, 0x4000|10, &[])
                                                        };
                                                        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), channel_state, 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 = {
                        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), channel_state, 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());
                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::LightningError { err: msg.reason.clone() }), channel_state, 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), channel_state, chan);
                                }
                                try_chan_entry!(self, chan.get_mut().update_fail_malformed_htlc(&msg, HTLCFailReason::Reason { failure_code: msg.failure_code, data: Vec::new() }), channel_state, 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, closing_signed, monitor_update) =
                                        match chan.get_mut().commitment_signed(&msg, &self.fee_estimator, &self.logger) {
                                                Err((None, e)) => try_chan_entry!(self, Err(e), channel_state, 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), channel_state, chan);
                                                        unreachable!();
                                                },
                                                Ok(res) => res
                                        };
                                if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                        return_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::RevokeAndACKFirst, true, commitment_signed.is_some());
                                        //TODO: Rebroadcast closing_signed if present on monitor update restoration
                                }
                                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,
                                                },
                                        });
                                }
                                if let Some(msg) = closing_signed {
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendClosingSigned {
                                                node_id: counterparty_node_id.clone(),
                                                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, Vec<(PendingHTLCInfo, u64)>)]) {
                for &mut (prev_short_channel_id, prev_funding_outpoint, ref mut pending_forwards) in per_source_pending_forwards {
                        let mut forward_event = None;
                        if !pending_forwards.is_empty() {
                                let mut channel_state = self.channel_state.lock().unwrap();
                                if channel_state.forward_htlcs.is_empty() {
                                        forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS))
                                }
                                for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
                                        match channel_state.forward_htlcs.entry(match forward_info.routing {
                                                        PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
                                                        PendingHTLCRouting::Receive { .. } => 0,
                                        }) {
                                                hash_map::Entry::Occupied(mut entry) => {
                                                        entry.get_mut().push(HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_funding_outpoint,
                                                                                                        prev_htlc_id, forward_info });
                                                },
                                                hash_map::Entry::Vacant(entry) => {
                                                        entry.insert(vec!(HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_funding_outpoint,
                                                                                                     prev_htlc_id, forward_info }));
                                                }
                                        }
                                }
                        }
                        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_frozen_for_monitor = chan.get().is_awaiting_monitor_update();
                                        let (commitment_update, pending_forwards, pending_failures, closing_signed, monitor_update, htlcs_to_fail_in) =
                                                break_chan_entry!(self, chan.get_mut().revoke_and_ack(&msg, &self.fee_estimator, &self.logger), channel_state, chan);
                                        htlcs_to_fail = htlcs_to_fail_in;
                                        if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                if was_frozen_for_monitor {
                                                        assert!(commitment_update.is_none() && closing_signed.is_none() && pending_forwards.is_empty() && pending_failures.is_empty());
                                                        break Err(MsgHandleErrInternal::ignore_no_close("Previous monitor update failure prevented responses to RAA".to_owned()));
                                                } else {
                                                        if let Err(e) = handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, commitment_update.is_some(), pending_forwards, pending_failures) {
                                                                break Err(e);
                                                        } else { unreachable!(); }
                                                }
                                        }
                                        if let Some(updates) = commitment_update {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                        node_id: counterparty_node_id.clone(),
                                                        updates,
                                                });
                                        }
                                        if let Some(msg) = closing_signed {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendClosingSigned {
                                                        node_id: counterparty_node_id.clone(),
                                                        msg,
                                                });
                                        }
                                        break Ok((pending_forwards, pending_failures, chan.get().get_short_channel_id().expect("RAA should only work on a short-id-available channel"), chan.get().get_funding_txo().unwrap()))
                                },
                                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);
                match res {
                        Ok((pending_forwards, mut pending_failures, short_channel_id, channel_outpoint)) => {
                                for failure in pending_failures.drain(..) {
                                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), failure.0, &failure.1, failure.2);
                                }
                                self.forward_htlcs(&mut [(short_channel_id, channel_outpoint, pending_forwards)]);
                                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), channel_state, 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}));
                                }

                                let our_node_id = self.get_our_node_id();
                                let (announcement, our_bitcoin_sig) =
                                        try_chan_entry!(self, chan.get_mut().get_channel_announcement(our_node_id.clone(), self.genesis_hash.clone()), channel_state, chan);

                                let were_node_one = announcement.node_id_1 == our_node_id;
                                let msghash = hash_to_message!(&Sha256dHash::hash(&announcement.encode()[..])[..]);
                                {
                                        let their_node_key = if were_node_one { &announcement.node_id_2 } else { &announcement.node_id_1 };
                                        let their_bitcoin_key = if were_node_one { &announcement.bitcoin_key_2 } else { &announcement.bitcoin_key_1 };
                                        match (self.secp_ctx.verify(&msghash, &msg.node_signature, their_node_key),
                                                   self.secp_ctx.verify(&msghash, &msg.bitcoin_signature, their_bitcoin_key)) {
                                                (Err(e), _) => {
                                                        let chan_err: ChannelError = ChannelError::Close(format!("Bad announcement_signatures. Failed to verify node_signature: {:?}. Maybe using different node_secret for transport and routing msg? UnsignedChannelAnnouncement used for verification is {:?}. their_node_key is {:?}", e, &announcement, their_node_key));
                                                        try_chan_entry!(self, Err(chan_err), channel_state, chan);
                                                },
                                                (_, Err(e)) => {
                                                        let chan_err: ChannelError = ChannelError::Close(format!("Bad announcement_signatures. Failed to verify bitcoin_signature: {:?}. UnsignedChannelAnnouncement used for verification is {:?}. their_bitcoin_key is ({:?})", e, &announcement, their_bitcoin_key));
                                                        try_chan_entry!(self, Err(chan_err), channel_state, chan);
                                                },
                                                _ => {}
                                        }
                                }

                                let our_node_sig = self.secp_ctx.sign(&msghash, &self.our_network_key);

                                channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelAnnouncement {
                                        msg: msgs::ChannelAnnouncement {
                                                node_signature_1: if were_node_one { our_node_sig } else { msg.node_signature },
                                                node_signature_2: if were_node_one { msg.node_signature } else { our_node_sig },
                                                bitcoin_signature_1: if were_node_one { our_bitcoin_sig } else { msg.bitcoin_signature },
                                                bitcoin_signature_2: if were_node_one { msg.bitcoin_signature } else { our_bitcoin_sig },
                                                contents: announcement,
                                        },
                                        update_msg: self.get_channel_update(chan.get()).unwrap(), // can only fail if we're not in a ready state
                                });
                        },
                        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_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) -> 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));
                                }
                                // 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 (funding_locked, revoke_and_ack, commitment_update, monitor_update_opt, mut order, shutdown) =
                                        try_chan_entry!(self, chan.get_mut().channel_reestablish(msg, &self.logger), channel_state, chan);
                                if let Some(monitor_update) = monitor_update_opt {
                                        if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                // channel_reestablish doesn't guarantee the order it returns is sensical
                                                // for the messages it returns, but if we're setting what messages to
                                                // re-transmit on monitor update success, we need to make sure it is sane.
                                                if revoke_and_ack.is_none() {
                                                        order = RAACommitmentOrder::CommitmentFirst;
                                                }
                                                if commitment_update.is_none() {
                                                        order = RAACommitmentOrder::RevokeAndACKFirst;
                                                }
                                                return_monitor_err!(self, e, channel_state, chan, order, revoke_and_ack.is_some(), commitment_update.is_some());
                                                //TODO: Resend the funding_locked if needed once we get the monitor running again
                                        }
                                }
                                if let Some(msg) = funding_locked {
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendFundingLocked {
                                                node_id: counterparty_node_id.clone(),
                                                msg
                                        });
                                }
                                macro_rules! send_raa { () => {
                                        if let Some(msg) = revoke_and_ack {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendRevokeAndACK {
                                                        node_id: counterparty_node_id.clone(),
                                                        msg
                                                });
                                        }
                                } }
                                macro_rules! send_cu { () => {
                                        if let Some(updates) = commitment_update {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
                                                        node_id: counterparty_node_id.clone(),
                                                        updates
                                                });
                                        }
                                } }
                                match order {
                                        RAACommitmentOrder::RevokeAndACKFirst => {
                                                send_raa!();
                                                send_cu!();
                                        },
                                        RAACommitmentOrder::CommitmentFirst => {
                                                send_cu!();
                                                send_raa!();
                                        },
                                }
                                if let Some(msg) = shutdown {
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                node_id: counterparty_node_id.clone(),
                                                msg,
                                        });
                                }
                                Ok(())
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
        }

        /// Begin Update fee process. Allowed only on an outbound channel.
        /// If successful, will generate a UpdateHTLCs event, so you should probably poll
        /// PeerManager::process_events afterwards.
        /// Note: This API is likely to change!
        /// (C-not exported) Cause its doc(hidden) anyway
        #[doc(hidden)]
        pub fn update_fee(&self, channel_id: [u8;32], feerate_per_kw: u32) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let counterparty_node_id;
                let err: 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) {
                                hash_map::Entry::Vacant(_) => return Err(APIError::APIMisuseError{err: format!("Failed to find corresponding channel for id {}", channel_id.to_hex())}),
                                hash_map::Entry::Occupied(mut chan) => {
                                        if !chan.get().is_outbound() {
                                                return Err(APIError::APIMisuseError{err: "update_fee cannot be sent for an inbound channel".to_owned()});
                                        }
                                        if chan.get().is_awaiting_monitor_update() {
                                                return Err(APIError::MonitorUpdateFailed);
                                        }
                                        if !chan.get().is_live() {
                                                return Err(APIError::ChannelUnavailable{err: "Channel is either not yet fully established or peer is currently disconnected".to_owned()});
                                        }
                                        counterparty_node_id = chan.get().get_counterparty_node_id();
                                        if let Some((update_fee, commitment_signed, monitor_update)) =
                                                        break_chan_entry!(self, chan.get_mut().send_update_fee_and_commit(feerate_per_kw, &self.logger), channel_state, chan)
                                        {
                                                if let Err(_e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
                                                        unimplemented!();
                                                }
                                                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::new(),
                                                                update_fail_htlcs: Vec::new(),
                                                                update_fail_malformed_htlcs: Vec::new(),
                                                                update_fee: Some(update_fee),
                                                                commitment_signed,
                                                        },
                                                });
                                        }
                                },
                        }
                        return Ok(())
                };

                match handle_error!(self, err, counterparty_node_id) {
                        Ok(_) => unreachable!(),
                        Err(e) => { Err(APIError::APIMisuseError { err: e.err })}
                }
        }

        /// Process pending events from the `chain::Watch`.
        fn process_pending_monitor_events(&self) {
                let mut failed_channels = Vec::new();
                {
                        for monitor_event in self.chain_monitor.release_pending_monitor_events() {
                                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);
                                                } else {
                                                        log_trace!(self.logger, "Failing HTLC with hash {} from our monitor", log_bytes!(htlc_update.payment_hash.0));
                                                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_update.source, &htlc_update.payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() });
                                                }
                                        },
                                        MonitorEvent::CommitmentTxBroadcasted(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 short_to_id = &mut channel_state.short_to_id;
                                                let pending_msg_events = &mut channel_state.pending_msg_events;
                                                if let Some(mut chan) = by_id.remove(&funding_outpoint.to_channel_id()) {
                                                        if let Some(short_id) = chan.get_short_channel_id() {
                                                                short_to_id.remove(&short_id);
                                                        }
                                                        failed_channels.push(chan.force_shutdown(false));
                                                        if let Ok(update) = self.get_channel_update(&chan) {
                                                                pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                        msg: update
                                                                });
                                                        }
                                                }
                                        },
                                }
                        }
                }

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

        /// 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_chan_freshness_every_min, 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);
                }
        }
}

impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> MessageSendEventsProvider for ChannelManager<Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
                                L::Target: Logger,
{
        fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
                //TODO: This behavior should be documented. It's non-intuitive that we query
                // ChannelMonitors when clearing other events.
                self.process_pending_monitor_events();

                let mut ret = Vec::new();
                let mut channel_state = self.channel_state.lock().unwrap();
                mem::swap(&mut ret, &mut channel_state.pending_msg_events);
                ret
        }
}

impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> EventsProvider for ChannelManager<Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
                                L::Target: Logger,
{
        fn get_and_clear_pending_events(&self) -> Vec<Event> {
                //TODO: This behavior should be documented. It's non-intuitive that we query
                // ChannelMonitors when clearing other events.
                self.process_pending_monitor_events();

                let mut ret = Vec::new();
                let mut pending_events = self.pending_events.lock().unwrap();
                mem::swap(&mut ret, &mut *pending_events);
                ret
        }
}

impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> chain::Listen for ChannelManager<Signer, M, T, K, F, L>
where
        M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn block_connected(&self, block: &Block, height: u32) {
                let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
                ChannelManager::block_connected(self, &block.header, &txdata, height);
        }

        fn block_disconnected(&self, header: &BlockHeader, _height: u32) {
                ChannelManager::block_disconnected(self, header);
        }
}

impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        /// Updates channel state based on transactions seen in a connected block.
        pub fn block_connected(&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, "Block {} at height {} connected", block_hash, height);

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

                self.latest_block_height.store(height as usize, Ordering::Release);
                *self.last_block_hash.write().unwrap() = block_hash;

                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 short_to_id = &mut channel_state.short_to_id;
                        let pending_msg_events = &mut channel_state.pending_msg_events;
                        channel_state.by_id.retain(|_, channel| {
                                let res = channel.block_connected(header, txdata, height);
                                if let Ok((chan_res, mut timed_out_pending_htlcs)) = res {
                                        for (source, payment_hash) in timed_out_pending_htlcs.drain(..) {
                                                let chan_update = self.get_channel_update(&channel).map(|u| u.encode_with_len()).unwrap(); // Cannot add/recv HTLCs before we have a short_id so unwrap is safe
                                                timed_out_htlcs.push((source, payment_hash,  HTLCFailReason::Reason {
                                                        failure_code: 0x1000 | 14, // expiry_too_soon, or at least it is now
                                                        data: chan_update,
                                                }));
                                        }
                                        if let Some(funding_locked) = chan_res {
                                                pending_msg_events.push(events::MessageSendEvent::SendFundingLocked {
                                                        node_id: channel.get_counterparty_node_id(),
                                                        msg: funding_locked,
                                                });
                                                if let Some(announcement_sigs) = self.get_announcement_sigs(channel) {
                                                        log_trace!(self.logger, "Sending funding_locked and announcement_signatures for {}", log_bytes!(channel.channel_id()));
                                                        pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                                node_id: channel.get_counterparty_node_id(),
                                                                msg: announcement_sigs,
                                                        });
                                                } else {
                                                        log_trace!(self.logger, "Sending funding_locked WITHOUT announcement_signatures for {}", log_bytes!(channel.channel_id()));
                                                }
                                                short_to_id.insert(channel.get_short_channel_id().unwrap(), channel.channel_id());
                                        }
                                } else if let Err(e) = res {
                                        pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                node_id: channel.get_counterparty_node_id(),
                                                action: msgs::ErrorAction::SendErrorMessage { msg: e },
                                        });
                                        return false;
                                }
                                if let Some(funding_txo) = channel.get_funding_txo() {
                                        for &(_, tx) in txdata.iter() {
                                                for inp in tx.input.iter() {
                                                        if inp.previous_output == funding_txo.into_bitcoin_outpoint() {
                                                                log_trace!(self.logger, "Detected channel-closing tx {} spending {}:{}, closing channel {}", tx.txid(), inp.previous_output.txid, inp.previous_output.vout, log_bytes!(channel.channel_id()));
                                                                if let Some(short_id) = channel.get_short_channel_id() {
                                                                        short_to_id.remove(&short_id);
                                                                }
                                                                // It looks like our counterparty went on-chain. Close the channel.
                                                                failed_channels.push(channel.force_shutdown(true));
                                                                if let Ok(update) = self.get_channel_update(&channel) {
                                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                msg: update
                                                                        });
                                                                }
                                                                return false;
                                                        }
                                                }
                                        }
                                }
                                true
                        });

                        channel_state.claimable_htlcs.retain(|&(ref 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 = byte_utils::be64_to_array(htlc.value).to_vec();
                                                htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array(height));
                                                timed_out_htlcs.push((HTLCSource::PreviousHopData(htlc.prev_hop.clone()), payment_hash.clone(), HTLCFailReason::Reason {
                                                        failure_code: 0x4000 | 15,
                                                        data: htlc_msat_height_data
                                                }));
                                                false
                                        } else { true }
                                });
                                !htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
                        });
                }

                self.handle_init_event_channel_failures(failed_channels);

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

                loop {
                        // Update last_node_announcement_serial 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
                        // last_node_announcement_serial or decide we don't need to.
                        let old_serial = self.last_node_announcement_serial.load(Ordering::Acquire);
                        if old_serial >= header.time as usize { break; }
                        if self.last_node_announcement_serial.compare_exchange(old_serial, header.time as usize, Ordering::AcqRel, Ordering::Relaxed).is_ok() {
                                break;
                        }
                }
        }

        /// Updates channel state based on a disconnected block.
        ///
        /// If necessary, the channel may be force-closed without letting the counterparty participate
        /// in the shutdown.
        pub fn block_disconnected(&self, header: &BlockHeader) {
                // 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 _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);

                self.latest_block_height.fetch_sub(1, Ordering::AcqRel);
                *self.last_block_hash.write().unwrap() = header.prev_blockhash;

                let mut failed_channels = Vec::new();
                {
                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
                        let short_to_id = &mut channel_state.short_to_id;
                        let pending_msg_events = &mut channel_state.pending_msg_events;
                        channel_state.by_id.retain(|_,  v| {
                                if v.block_disconnected(header) {
                                        if let Some(short_id) = v.get_short_channel_id() {
                                                short_to_id.remove(&short_id);
                                        }
                                        failed_channels.push(v.force_shutdown(true));
                                        if let Ok(update) = self.get_channel_update(&v) {
                                                pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                        msg: update
                                                });
                                        }
                                        false
                                } else {
                                        true
                                }
                        });
                }

                self.handle_init_event_channel_failures(failed_channels);
        }

        /// 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` or `await_persistable_update_timeout` is guaranteed to be woken
        /// up.
        /// Note that the feature `allow_wallclock_use` must be enabled to use this function.
        #[cfg(any(test, feature = "allow_wallclock_use"))]
        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` or `await_persistable_update_timeout` is guaranteed to be woken
        /// up.
        pub fn await_persistable_update(&self) {
                self.persistence_notifier.wait()
        }

        #[cfg(any(test, feature = "_test_utils"))]
        pub fn get_persistence_condvar_value(&self) -> bool {
                let mutcond = &self.persistence_notifier.persistence_lock;
                let &(ref mtx, _) = mutcond;
                let guard = mtx.lock().unwrap();
                *guard
        }
}

impl<Signer: Sign, M: Deref + Sync + Send, T: Deref + Sync + Send, K: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send>
        ChannelMessageHandler for ChannelManager<Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        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::new(&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::new(&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::new(&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::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_funding_signed(counterparty_node_id, msg), *counterparty_node_id);
        }

        fn handle_funding_locked(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingLocked) {
                let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_funding_locked(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::new(&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::new(&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::new(&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::new(&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::new(&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::new(&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::new(&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::new(&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::new(&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::new(&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_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) {
                let _persistence_guard = PersistenceNotifierGuard::new(&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::new(&self.total_consistency_lock, &self.persistence_notifier);
                let mut failed_channels = Vec::new();
                let mut failed_payments = 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 short_to_id = &mut channel_state.short_to_id;
                        let pending_msg_events = &mut channel_state.pending_msg_events;
                        if no_connection_possible {
                                log_debug!(self.logger, "Failing all channels with {} due to no_connection_possible", log_pubkey!(counterparty_node_id));
                                channel_state.by_id.retain(|_, chan| {
                                        if chan.get_counterparty_node_id() == *counterparty_node_id {
                                                if let Some(short_id) = chan.get_short_channel_id() {
                                                        short_to_id.remove(&short_id);
                                                }
                                                failed_channels.push(chan.force_shutdown(true));
                                                if let Ok(update) = self.get_channel_update(&chan) {
                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                msg: update
                                                        });
                                                }
                                                false
                                        } else {
                                                true
                                        }
                                });
                        } else {
                                log_debug!(self.logger, "Marking channels with {} disconnected and generating channel_updates", log_pubkey!(counterparty_node_id));
                                channel_state.by_id.retain(|_, chan| {
                                        if chan.get_counterparty_node_id() == *counterparty_node_id {
                                                // Note that currently on channel reestablish we assert that there are no
                                                // holding cell add-HTLCs, so if in the future we stop removing uncommitted HTLCs
                                                // on peer disconnect here, there will need to be corresponding changes in
                                                // reestablish logic.
                                                let failed_adds = chan.remove_uncommitted_htlcs_and_mark_paused(&self.logger);
                                                chan.to_disabled_marked();
                                                if !failed_adds.is_empty() {
                                                        let chan_update = self.get_channel_update(&chan).map(|u| u.encode_with_len()).unwrap(); // Cannot add/recv HTLCs before we have a short_id so unwrap is safe
                                                        failed_payments.push((chan_update, failed_adds));
                                                }
                                                if chan.is_shutdown() {
                                                        if let Some(short_id) = chan.get_short_channel_id() {
                                                                short_to_id.remove(&short_id);
                                                        }
                                                        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::SendFundingLocked { 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::BroadcastChannelAnnouncement { .. } => true,
                                        &events::MessageSendEvent::BroadcastNodeAnnouncement { .. } => true,
                                        &events::MessageSendEvent::BroadcastChannelUpdate { .. } => true,
                                        &events::MessageSendEvent::HandleError { ref node_id, .. } => node_id != counterparty_node_id,
                                        &events::MessageSendEvent::PaymentFailureNetworkUpdate { .. } => true,
                                        &events::MessageSendEvent::SendChannelRangeQuery { .. } => false,
                                        &events::MessageSendEvent::SendShortIdsQuery { .. } => 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);
                }
                for (chan_update, mut htlc_sources) in failed_payments {
                        for (htlc_source, payment_hash) in htlc_sources.drain(..) {
                                self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source, &payment_hash, HTLCFailReason::Reason { failure_code: 0x1000 | 7, data: chan_update.clone() });
                        }
                }
        }

        fn peer_connected(&self, counterparty_node_id: &PublicKey, init_msg: &msgs::Init) {
                log_debug!(self.logger, "Generating channel_reestablish events for {}", log_pubkey!(counterparty_node_id));

                let _persistence_guard = PersistenceNotifierGuard::new(&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| {
                        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 }
                });
                //TODO: Also re-broadcast announcement_signatures
        }

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

                if msg.channel_id == [0; 32] {
                        for chan in self.list_channels() {
                                if chan.remote_network_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, Some(counterparty_node_id));
                                }
                        }
                } else {
                        // 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, Some(counterparty_node_id));
                }
        }
}

/// Used to signal to the ChannelManager persister that the manager needs to be re-persisted to
/// disk/backups, through `await_persistable_update_timeout` and `await_persistable_update`.
struct PersistenceNotifier {
        /// Users won't access the persistence_lock directly, but rather wait on its bool using
        /// `wait_timeout` and `wait`.
        persistence_lock: (Mutex<bool>, Condvar),
}

impl PersistenceNotifier {
        fn new() -> Self {
                Self {
                        persistence_lock: (Mutex::new(false), Condvar::new()),
                }
        }

        fn wait(&self) {
                loop {
                        let &(ref mtx, ref cvar) = &self.persistence_lock;
                        let mut guard = mtx.lock().unwrap();
                        guard = cvar.wait(guard).unwrap();
                        let result = *guard;
                        if result {
                                *guard = false;
                                return
                        }
                }
        }

        #[cfg(any(test, feature = "allow_wallclock_use"))]
        fn wait_timeout(&self, max_wait: Duration) -> bool {
                let current_time = Instant::now();
                loop {
                        let &(ref mtx, ref cvar) = &self.persistence_lock;
                        let mut guard = mtx.lock().unwrap();
                        guard = cvar.wait_timeout(guard, max_wait).unwrap().0;
                        // Due to spurious wakeups that can happen on `wait_timeout`, here we need to check if the
                        // desired wait time has actually passed, and if not then restart the loop with a reduced wait
                        // time. Note that this logic can be highly simplified through the use of
                        // `Condvar::wait_while` and `Condvar::wait_timeout_while`, if and when our MSRV is raised to
                        // 1.42.0.
                        let elapsed = current_time.elapsed();
                        let result = *guard;
                        if result || elapsed >= max_wait {
                                *guard = false;
                                return result;
                        }
                        match max_wait.checked_sub(elapsed) {
                                None => return result,
                                Some(_) => continue
                        }
                }
        }

        // Signal to the ChannelManager persister that there are updates necessitating persisting to disk.
        fn notify(&self) {
                let &(ref persist_mtx, ref cnd) = &self.persistence_lock;
                let mut persistence_lock = persist_mtx.lock().unwrap();
                *persistence_lock = true;
                mem::drop(persistence_lock);
                cnd.notify_all();
        }
}

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

impl Writeable for PendingHTLCInfo {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                match &self.routing {
                        &PendingHTLCRouting::Forward { ref onion_packet, ref short_channel_id } => {
                                0u8.write(writer)?;
                                onion_packet.write(writer)?;
                                short_channel_id.write(writer)?;
                        },
                        &PendingHTLCRouting::Receive { ref payment_data, ref incoming_cltv_expiry } => {
                                1u8.write(writer)?;
                                payment_data.write(writer)?;
                                incoming_cltv_expiry.write(writer)?;
                        },
                }
                self.incoming_shared_secret.write(writer)?;
                self.payment_hash.write(writer)?;
                self.amt_to_forward.write(writer)?;
                self.outgoing_cltv_value.write(writer)?;
                Ok(())
        }
}

impl Readable for PendingHTLCInfo {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<PendingHTLCInfo, DecodeError> {
                Ok(PendingHTLCInfo {
                        routing: match Readable::read(reader)? {
                                0u8 => PendingHTLCRouting::Forward {
                                        onion_packet: Readable::read(reader)?,
                                        short_channel_id: Readable::read(reader)?,
                                },
                                1u8 => PendingHTLCRouting::Receive {
                                        payment_data: Readable::read(reader)?,
                                        incoming_cltv_expiry: Readable::read(reader)?,
                                },
                                _ => return Err(DecodeError::InvalidValue),
                        },
                        incoming_shared_secret: Readable::read(reader)?,
                        payment_hash: Readable::read(reader)?,
                        amt_to_forward: Readable::read(reader)?,
                        outgoing_cltv_value: Readable::read(reader)?,
                })
        }
}

impl Writeable for HTLCFailureMsg {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                match self {
                        &HTLCFailureMsg::Relay(ref fail_msg) => {
                                0u8.write(writer)?;
                                fail_msg.write(writer)?;
                        },
                        &HTLCFailureMsg::Malformed(ref fail_msg) => {
                                1u8.write(writer)?;
                                fail_msg.write(writer)?;
                        }
                }
                Ok(())
        }
}

impl Readable for HTLCFailureMsg {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<HTLCFailureMsg, DecodeError> {
                match <u8 as Readable>::read(reader)? {
                        0 => Ok(HTLCFailureMsg::Relay(Readable::read(reader)?)),
                        1 => Ok(HTLCFailureMsg::Malformed(Readable::read(reader)?)),
                        _ => Err(DecodeError::InvalidValue),
                }
        }
}

impl Writeable for PendingHTLCStatus {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                match self {
                        &PendingHTLCStatus::Forward(ref forward_info) => {
                                0u8.write(writer)?;
                                forward_info.write(writer)?;
                        },
                        &PendingHTLCStatus::Fail(ref fail_msg) => {
                                1u8.write(writer)?;
                                fail_msg.write(writer)?;
                        }
                }
                Ok(())
        }
}

impl Readable for PendingHTLCStatus {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<PendingHTLCStatus, DecodeError> {
                match <u8 as Readable>::read(reader)? {
                        0 => Ok(PendingHTLCStatus::Forward(Readable::read(reader)?)),
                        1 => Ok(PendingHTLCStatus::Fail(Readable::read(reader)?)),
                        _ => Err(DecodeError::InvalidValue),
                }
        }
}

impl_writeable!(HTLCPreviousHopData, 0, {
        short_channel_id,
        outpoint,
        htlc_id,
        incoming_packet_shared_secret
});

impl_writeable!(ClaimableHTLC, 0, {
        prev_hop,
        value,
        payment_data,
        cltv_expiry
});

impl Writeable for HTLCSource {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                match self {
                        &HTLCSource::PreviousHopData(ref hop_data) => {
                                0u8.write(writer)?;
                                hop_data.write(writer)?;
                        },
                        &HTLCSource::OutboundRoute { ref path, ref session_priv, ref first_hop_htlc_msat } => {
                                1u8.write(writer)?;
                                path.write(writer)?;
                                session_priv.write(writer)?;
                                first_hop_htlc_msat.write(writer)?;
                        }
                }
                Ok(())
        }
}

impl Readable for HTLCSource {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<HTLCSource, DecodeError> {
                match <u8 as Readable>::read(reader)? {
                        0 => Ok(HTLCSource::PreviousHopData(Readable::read(reader)?)),
                        1 => Ok(HTLCSource::OutboundRoute {
                                path: Readable::read(reader)?,
                                session_priv: Readable::read(reader)?,
                                first_hop_htlc_msat: Readable::read(reader)?,
                        }),
                        _ => Err(DecodeError::InvalidValue),
                }
        }
}

impl Writeable for HTLCFailReason {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                match self {
                        &HTLCFailReason::LightningError { ref err } => {
                                0u8.write(writer)?;
                                err.write(writer)?;
                        },
                        &HTLCFailReason::Reason { ref failure_code, ref data } => {
                                1u8.write(writer)?;
                                failure_code.write(writer)?;
                                data.write(writer)?;
                        }
                }
                Ok(())
        }
}

impl Readable for HTLCFailReason {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<HTLCFailReason, DecodeError> {
                match <u8 as Readable>::read(reader)? {
                        0 => Ok(HTLCFailReason::LightningError { err: Readable::read(reader)? }),
                        1 => Ok(HTLCFailReason::Reason {
                                failure_code: Readable::read(reader)?,
                                data: Readable::read(reader)?,
                        }),
                        _ => Err(DecodeError::InvalidValue),
                }
        }
}

impl Writeable for HTLCForwardInfo {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                match self {
                        &HTLCForwardInfo::AddHTLC { ref prev_short_channel_id, ref prev_funding_outpoint, ref prev_htlc_id, ref forward_info } => {
                                0u8.write(writer)?;
                                prev_short_channel_id.write(writer)?;
                                prev_funding_outpoint.write(writer)?;
                                prev_htlc_id.write(writer)?;
                                forward_info.write(writer)?;
                        },
                        &HTLCForwardInfo::FailHTLC { ref htlc_id, ref err_packet } => {
                                1u8.write(writer)?;
                                htlc_id.write(writer)?;
                                err_packet.write(writer)?;
                        },
                }
                Ok(())
        }
}

impl Readable for HTLCForwardInfo {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<HTLCForwardInfo, DecodeError> {
                match <u8 as Readable>::read(reader)? {
                        0 => Ok(HTLCForwardInfo::AddHTLC {
                                prev_short_channel_id: Readable::read(reader)?,
                                prev_funding_outpoint: Readable::read(reader)?,
                                prev_htlc_id: Readable::read(reader)?,
                                forward_info: Readable::read(reader)?,
                        }),
                        1 => Ok(HTLCForwardInfo::FailHTLC {
                                htlc_id: Readable::read(reader)?,
                                err_packet: Readable::read(reader)?,
                        }),
                        _ => Err(DecodeError::InvalidValue),
                }
        }
}

impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> Writeable for ChannelManager<Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                let _consistency_lock = self.total_consistency_lock.write().unwrap();

                writer.write_all(&[SERIALIZATION_VERSION; 1])?;
                writer.write_all(&[MIN_SERIALIZATION_VERSION; 1])?;

                self.genesis_hash.write(writer)?;
                (self.latest_block_height.load(Ordering::Acquire) as u32).write(writer)?;
                self.last_block_hash.read().unwrap().write(writer)?;

                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)?;
                        }
                }

                (channel_state.forward_htlcs.len() as u64).write(writer)?;
                for (short_channel_id, pending_forwards) in channel_state.forward_htlcs.iter() {
                        short_channel_id.write(writer)?;
                        (pending_forwards.len() as u64).write(writer)?;
                        for forward in pending_forwards {
                                forward.write(writer)?;
                        }
                }

                (channel_state.claimable_htlcs.len() as u64).write(writer)?;
                for (payment_hash, previous_hops) in channel_state.claimable_htlcs.iter() {
                        payment_hash.write(writer)?;
                        (previous_hops.len() as u64).write(writer)?;
                        for htlc in previous_hops.iter() {
                                htlc.write(writer)?;
                        }
                }

                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)?;
                                },
                        }
                }

                (self.last_node_announcement_serial.load(Ordering::Acquire) as u32).write(writer)?;

                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 ChannelMonitors.
/// 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 ChannelMonitors.
/// 5) Disconnect/connect blocks on the ChannelManager.
/// 6) Move the ChannelMonitors into your local chain::Watch.
///
/// Note that the ordering of #4-6 is not of importance, however all three 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.
pub struct ChannelManagerReadArgs<'a, Signer: 'a + Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        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<Signer>>,
}

impl<'a, Signer: 'a + Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
                T::Target: BroadcasterInterface,
                K::Target: KeysInterface<Signer = Signer>,
                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<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, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        ReadableArgs<ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>> for (BlockHash, Arc<ChannelManager<Signer, M, T, K, F, L>>)
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn read<R: ::std::io::Read>(reader: &mut R, args: ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>) -> Result<Self, DecodeError> {
                let (blockhash, chan_manager) = <(BlockHash, ChannelManager<Signer, M, T, K, F, L>)>::read(reader, args)?;
                Ok((blockhash, Arc::new(chan_manager)))
        }
}

impl<'a, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        ReadableArgs<ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>> for (BlockHash, ChannelManager<Signer, M, T, K, F, L>)
        where M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer = Signer>,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn read<R: ::std::io::Read>(reader: &mut R, mut args: ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>) -> Result<Self, DecodeError> {
                let _ver: u8 = Readable::read(reader)?;
                let min_ver: u8 = Readable::read(reader)?;
                if min_ver > SERIALIZATION_VERSION {
                        return Err(DecodeError::UnknownVersion);
                }

                let genesis_hash: BlockHash = Readable::read(reader)?;
                let latest_block_height: u32 = Readable::read(reader)?;
                let last_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 short_to_id = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                for _ in 0..channel_count {
                        let mut channel: Channel<Signer> = Channel::read(reader, &args.keys_manager)?;
                        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:
                                        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:
                                        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);
                                } else {
                                        if let Some(short_channel_id) = channel.get_short_channel_id() {
                                                short_to_id.insert(short_channel_id, channel.channel_id());
                                        }
                                        by_id.insert(channel.channel_id(), channel);
                                }
                        } else {
                                return Err(DecodeError::InvalidValue);
                        }
                }

                for (ref funding_txo, ref mut monitor) in args.channel_monitors.iter_mut() {
                        if !funding_txo_set.contains(funding_txo) {
                                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 = HashMap::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(Readable::read(reader)?);
                        }
                        claimable_htlcs.insert(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)?;

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

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

                        latest_block_height: AtomicUsize::new(latest_block_height as usize),
                        last_block_hash: RwLock::new(last_block_hash),
                        secp_ctx,

                        channel_state: Mutex::new(ChannelHolder {
                                by_id,
                                short_to_id,
                                forward_htlcs,
                                claimable_htlcs,
                                pending_msg_events: Vec::new(),
                        }),
                        our_network_key: args.keys_manager.get_node_secret(),

                        last_node_announcement_serial: AtomicUsize::new(last_node_announcement_serial 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: PersistenceNotifier::new(),

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

                for htlc_source in failed_htlcs.drain(..) {
                        channel_manager.fail_htlc_backwards_internal(channel_manager.channel_state.lock().unwrap(), htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() });
                }

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

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

#[cfg(test)]
mod tests {
        use ln::channelmanager::PersistenceNotifier;
        use std::sync::Arc;
        use std::sync::atomic::{AtomicBool, Ordering};
        use std::thread;
        use std::time::Duration;

        #[test]
        fn test_wait_timeout() {
                let persistence_notifier = Arc::new(PersistenceNotifier::new());
                let thread_notifier = Arc::clone(&persistence_notifier);

                let exit_thread = Arc::new(AtomicBool::new(false));
                let exit_thread_clone = exit_thread.clone();
                thread::spawn(move || {
                        loop {
                                let &(ref persist_mtx, ref cnd) = &thread_notifier.persistence_lock;
                                let mut persistence_lock = persist_mtx.lock().unwrap();
                                *persistence_lock = true;
                                cnd.notify_all();

                                if exit_thread_clone.load(Ordering::SeqCst) {
                                        break
                                }
                        }
                });

                // Check that we can block indefinitely until updates are available.
                let _ = persistence_notifier.wait();

                // Check that the PersistenceNotifier will return after the given duration if updates are
                // available.
                loop {
                        if persistence_notifier.wait_timeout(Duration::from_millis(100)) {
                                break
                        }
                }

                exit_thread.store(true, Ordering::SeqCst);

                // Check that the PersistenceNotifier will return after the given duration even if no updates
                // are available.
                loop {
                        if !persistence_notifier.wait_timeout(Duration::from_millis(100)) {
                                break
                        }
                }
        }
}