peer_handler.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.

//! Top level peer message handling and socket handling logic lives here.
//!
//! Instead of actually servicing sockets ourselves we require that you implement the
//! SocketDescriptor interface and use that to receive actions which you should perform on the
//! socket, and call into PeerManager with bytes read from the socket. The PeerManager will then
//! call into the provided message handlers (probably a ChannelManager and NetGraphmsgHandler) with messages
//! they should handle, and encoding/sending response messages.

use bitcoin::secp256k1::key::{SecretKey,PublicKey};

use ln::features::InitFeatures;
use ln::msgs;
use ln::msgs::{ChannelMessageHandler, LightningError, RoutingMessageHandler};
use ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
use util::ser::{VecWriter, Writeable, Writer};
use ln::peer_channel_encryptor::{PeerChannelEncryptor,NextNoiseStep};
use ln::wire;
use ln::wire::Encode;
use util::atomic_counter::AtomicCounter;
use util::events::{MessageSendEvent, MessageSendEventsProvider};
use util::logger::Logger;
use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};

use prelude::*;
use io;
use alloc::collections::LinkedList;
use sync::{Arc, Mutex};
use core::{cmp, hash, fmt, mem};
use core::ops::Deref;
use core::convert::Infallible;
#[cfg(feature = "std")] use std::error;

use bitcoin::hashes::sha256::Hash as Sha256;
use bitcoin::hashes::sha256::HashEngine as Sha256Engine;
use bitcoin::hashes::{HashEngine, Hash};

/// Handler for BOLT1-compliant messages.
pub trait CustomMessageHandler: wire::CustomMessageReader {
	/// Called with the message type that was received and the buffer to be read.
	/// Can return a `MessageHandlingError` if the message could not be handled.
	fn handle_custom_message(&self, msg: Self::CustomMessage, sender_node_id: &PublicKey) -> Result<(), LightningError>;

	/// Gets the list of pending messages which were generated by the custom message
	/// handler, clearing the list in the process. The first tuple element must
	/// correspond to the intended recipients node ids. If no connection to one of the
	/// specified node does not exist, the message is simply not sent to it.
	fn get_and_clear_pending_msg(&self) -> Vec<(PublicKey, Self::CustomMessage)>;
}

/// A dummy struct which implements `RoutingMessageHandler` without storing any routing information
/// or doing any processing. You can provide one of these as the route_handler in a MessageHandler.
pub struct IgnoringMessageHandler{}
impl MessageSendEventsProvider for IgnoringMessageHandler {
	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> { Vec::new() }
}
impl RoutingMessageHandler for IgnoringMessageHandler {
	fn handle_node_announcement(&self, _msg: &msgs::NodeAnnouncement) -> Result<bool, LightningError> { Ok(false) }
	fn handle_channel_announcement(&self, _msg: &msgs::ChannelAnnouncement) -> Result<bool, LightningError> { Ok(false) }
	fn handle_channel_update(&self, _msg: &msgs::ChannelUpdate) -> Result<bool, LightningError> { Ok(false) }
	fn get_next_channel_announcements(&self, _starting_point: u64, _batch_amount: u8) ->
		Vec<(msgs::ChannelAnnouncement, Option<msgs::ChannelUpdate>, Option<msgs::ChannelUpdate>)> { Vec::new() }
	fn get_next_node_announcements(&self, _starting_point: Option<&PublicKey>, _batch_amount: u8) -> Vec<msgs::NodeAnnouncement> { Vec::new() }
	fn sync_routing_table(&self, _their_node_id: &PublicKey, _init: &msgs::Init) {}
	fn handle_reply_channel_range(&self, _their_node_id: &PublicKey, _msg: msgs::ReplyChannelRange) -> Result<(), LightningError> { Ok(()) }
	fn handle_reply_short_channel_ids_end(&self, _their_node_id: &PublicKey, _msg: msgs::ReplyShortChannelIdsEnd) -> Result<(), LightningError> { Ok(()) }
	fn handle_query_channel_range(&self, _their_node_id: &PublicKey, _msg: msgs::QueryChannelRange) -> Result<(), LightningError> { Ok(()) }
	fn handle_query_short_channel_ids(&self, _their_node_id: &PublicKey, _msg: msgs::QueryShortChannelIds) -> Result<(), LightningError> { Ok(()) }
}
impl Deref for IgnoringMessageHandler {
	type Target = IgnoringMessageHandler;
	fn deref(&self) -> &Self { self }
}

// Implement Type for Infallible, note that it cannot be constructed, and thus you can never call a
// method that takes self for it.
impl wire::Type for Infallible {
	fn type_id(&self) -> u16 {
		unreachable!();
	}
}
impl Writeable for Infallible {
	fn write<W: Writer>(&self, _: &mut W) -> Result<(), io::Error> {
		unreachable!();
	}
}

impl wire::CustomMessageReader for IgnoringMessageHandler {
	type CustomMessage = Infallible;
	fn read<R: io::Read>(&self, _message_type: u16, _buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError> {
		Ok(None)
	}
}

impl CustomMessageHandler for IgnoringMessageHandler {
	fn handle_custom_message(&self, _msg: Infallible, _sender_node_id: &PublicKey) -> Result<(), LightningError> {
		// Since we always return `None` in the read the handle method should never be called.
		unreachable!();
	}

	fn get_and_clear_pending_msg(&self) -> Vec<(PublicKey, Self::CustomMessage)> { Vec::new() }
}

/// A dummy struct which implements `ChannelMessageHandler` without having any channels.
/// You can provide one of these as the route_handler in a MessageHandler.
pub struct ErroringMessageHandler {
	message_queue: Mutex<Vec<MessageSendEvent>>
}
impl ErroringMessageHandler {
	/// Constructs a new ErroringMessageHandler
	pub fn new() -> Self {
		Self { message_queue: Mutex::new(Vec::new()) }
	}
	fn push_error(&self, node_id: &PublicKey, channel_id: [u8; 32]) {
		self.message_queue.lock().unwrap().push(MessageSendEvent::HandleError {
			action: msgs::ErrorAction::SendErrorMessage {
				msg: msgs::ErrorMessage { channel_id, data: "We do not support channel messages, sorry.".to_owned() },
			},
			node_id: node_id.clone(),
		});
	}
}
impl MessageSendEventsProvider for ErroringMessageHandler {
	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
		let mut res = Vec::new();
		mem::swap(&mut res, &mut self.message_queue.lock().unwrap());
		res
	}
}
impl ChannelMessageHandler for ErroringMessageHandler {
	// Any messages which are related to a specific channel generate an error message to let the
	// peer know we don't care about channels.
	fn handle_open_channel(&self, their_node_id: &PublicKey, _their_features: InitFeatures, msg: &msgs::OpenChannel) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.temporary_channel_id);
	}
	fn handle_accept_channel(&self, their_node_id: &PublicKey, _their_features: InitFeatures, msg: &msgs::AcceptChannel) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.temporary_channel_id);
	}
	fn handle_funding_created(&self, their_node_id: &PublicKey, msg: &msgs::FundingCreated) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.temporary_channel_id);
	}
	fn handle_funding_signed(&self, their_node_id: &PublicKey, msg: &msgs::FundingSigned) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_funding_locked(&self, their_node_id: &PublicKey, msg: &msgs::FundingLocked) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_shutdown(&self, their_node_id: &PublicKey, _their_features: &InitFeatures, msg: &msgs::Shutdown) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_closing_signed(&self, their_node_id: &PublicKey, msg: &msgs::ClosingSigned) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_update_add_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateAddHTLC) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_update_fulfill_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_update_fail_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_update_fail_malformed_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_commitment_signed(&self, their_node_id: &PublicKey, msg: &msgs::CommitmentSigned) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_revoke_and_ack(&self, their_node_id: &PublicKey, msg: &msgs::RevokeAndACK) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_update_fee(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFee) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_announcement_signatures(&self, their_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	fn handle_channel_reestablish(&self, their_node_id: &PublicKey, msg: &msgs::ChannelReestablish) {
		ErroringMessageHandler::push_error(self, their_node_id, msg.channel_id);
	}
	// msgs::ChannelUpdate does not contain the channel_id field, so we just drop them.
	fn handle_channel_update(&self, _their_node_id: &PublicKey, _msg: &msgs::ChannelUpdate) {}
	fn peer_disconnected(&self, _their_node_id: &PublicKey, _no_connection_possible: bool) {}
	fn peer_connected(&self, _their_node_id: &PublicKey, _msg: &msgs::Init) {}
	fn handle_error(&self, _their_node_id: &PublicKey, _msg: &msgs::ErrorMessage) {}
}
impl Deref for ErroringMessageHandler {
	type Target = ErroringMessageHandler;
	fn deref(&self) -> &Self { self }
}

/// Provides references to trait impls which handle different types of messages.
pub struct MessageHandler<CM: Deref, RM: Deref> where
		CM::Target: ChannelMessageHandler,
		RM::Target: RoutingMessageHandler {
	/// A message handler which handles messages specific to channels. Usually this is just a
	/// [`ChannelManager`] object or an [`ErroringMessageHandler`].
	///
	/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
	pub chan_handler: CM,
	/// A message handler which handles messages updating our knowledge of the network channel
	/// graph. Usually this is just a [`NetGraphMsgHandler`] object or an
	/// [`IgnoringMessageHandler`].
	///
	/// [`NetGraphMsgHandler`]: crate::routing::network_graph::NetGraphMsgHandler
	pub route_handler: RM,
}

/// Provides an object which can be used to send data to and which uniquely identifies a connection
/// to a remote host. You will need to be able to generate multiple of these which meet Eq and
/// implement Hash to meet the PeerManager API.
///
/// For efficiency, Clone should be relatively cheap for this type.
///
/// Two descriptors may compare equal (by [`cmp::Eq`] and [`hash::Hash`]) as long as the original
/// has been disconnected, the [`PeerManager`] has been informed of the disconnection (either by it
/// having triggered the disconnection or a call to [`PeerManager::socket_disconnected`]), and no
/// further calls to the [`PeerManager`] related to the original socket occur. This allows you to
/// use a file descriptor for your SocketDescriptor directly, however for simplicity you may wish
/// to simply use another value which is guaranteed to be globally unique instead.
pub trait SocketDescriptor : cmp::Eq + hash::Hash + Clone {
	/// Attempts to send some data from the given slice to the peer.
	///
	/// Returns the amount of data which was sent, possibly 0 if the socket has since disconnected.
	/// Note that in the disconnected case, [`PeerManager::socket_disconnected`] must still be
	/// called and further write attempts may occur until that time.
	///
	/// If the returned size is smaller than `data.len()`, a
	/// [`PeerManager::write_buffer_space_avail`] call must be made the next time more data can be
	/// written. Additionally, until a `send_data` event completes fully, no further
	/// [`PeerManager::read_event`] calls should be made for the same peer! Because this is to
	/// prevent denial-of-service issues, you should not read or buffer any data from the socket
	/// until then.
	///
	/// If a [`PeerManager::read_event`] call on this descriptor had previously returned true
	/// (indicating that read events should be paused to prevent DoS in the send buffer),
	/// `resume_read` may be set indicating that read events on this descriptor should resume. A
	/// `resume_read` of false carries no meaning, and should not cause any action.
	fn send_data(&mut self, data: &[u8], resume_read: bool) -> usize;
	/// Disconnect the socket pointed to by this SocketDescriptor.
	///
	/// You do *not* need to call [`PeerManager::socket_disconnected`] with this socket after this
	/// call (doing so is a noop).
	fn disconnect_socket(&mut self);
}

/// Error for PeerManager errors. If you get one of these, you must disconnect the socket and
/// generate no further read_event/write_buffer_space_avail/socket_disconnected calls for the
/// descriptor.
#[derive(Clone)]
pub struct PeerHandleError {
	/// Used to indicate that we probably can't make any future connections to this peer, implying
	/// we should go ahead and force-close any channels we have with it.
	pub no_connection_possible: bool,
}
impl fmt::Debug for PeerHandleError {
	fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
		formatter.write_str("Peer Sent Invalid Data")
	}
}
impl fmt::Display for PeerHandleError {
	fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
		formatter.write_str("Peer Sent Invalid Data")
	}
}

#[cfg(feature = "std")]
impl error::Error for PeerHandleError {
	fn description(&self) -> &str {
		"Peer Sent Invalid Data"
	}
}

enum InitSyncTracker{
	NoSyncRequested,
	ChannelsSyncing(u64),
	NodesSyncing(PublicKey),
}

/// The ratio between buffer sizes at which we stop sending initial sync messages vs when we stop
/// forwarding gossip messages to peers altogether.
const FORWARD_INIT_SYNC_BUFFER_LIMIT_RATIO: usize = 2;

/// When the outbound buffer has this many messages, we'll stop reading bytes from the peer until
/// we have fewer than this many messages in the outbound buffer again.
/// We also use this as the target number of outbound gossip messages to keep in the write buffer,
/// refilled as we send bytes.
const OUTBOUND_BUFFER_LIMIT_READ_PAUSE: usize = 10;
/// When the outbound buffer has this many messages, we'll simply skip relaying gossip messages to
/// the peer.
const OUTBOUND_BUFFER_LIMIT_DROP_GOSSIP: usize = OUTBOUND_BUFFER_LIMIT_READ_PAUSE * FORWARD_INIT_SYNC_BUFFER_LIMIT_RATIO;

/// If we've sent a ping, and are still awaiting a response, we may need to churn our way through
/// the socket receive buffer before receiving the ping.
///
/// On a fairly old Arm64 board, with Linux defaults, this can take as long as 20 seconds, not
/// including any network delays, outbound traffic, or the same for messages from other peers.
///
/// Thus, to avoid needlessly disconnecting a peer, we allow a peer to take this many timer ticks
/// per connected peer to respond to a ping, as long as they send us at least one message during
/// each tick, ensuring we aren't actually just disconnected.
/// With a timer tick interval of five seconds, this translates to about 30 seconds per connected
/// peer.
///
/// When we improve parallelism somewhat we should reduce this to e.g. this many timer ticks per
/// two connected peers, assuming most LDK-running systems have at least two cores.
const MAX_BUFFER_DRAIN_TICK_INTERVALS_PER_PEER: i8 = 6;

/// This is the minimum number of messages we expect a peer to be able to handle within one timer
/// tick. Once we have sent this many messages since the last ping, we send a ping right away to
/// ensures we don't just fill up our send buffer and leave the peer with too many messages to
/// process before the next ping.
const BUFFER_DRAIN_MSGS_PER_TICK: usize = 32;

struct Peer {
	channel_encryptor: PeerChannelEncryptor,
	their_node_id: Option<PublicKey>,
	their_features: Option<InitFeatures>,

	pending_outbound_buffer: LinkedList<Vec<u8>>,
	pending_outbound_buffer_first_msg_offset: usize,
	awaiting_write_event: bool,

	pending_read_buffer: Vec<u8>,
	pending_read_buffer_pos: usize,
	pending_read_is_header: bool,

	sync_status: InitSyncTracker,

	msgs_sent_since_pong: usize,
	awaiting_pong_timer_tick_intervals: i8,
	received_message_since_timer_tick: bool,
}

impl Peer {
	/// Returns true if the channel announcements/updates for the given channel should be
	/// forwarded to this peer.
	/// If we are sending our routing table to this peer and we have not yet sent channel
	/// announcements/updates for the given channel_id then we will send it when we get to that
	/// point and we shouldn't send it yet to avoid sending duplicate updates. If we've already
	/// sent the old versions, we should send the update, and so return true here.
	fn should_forward_channel_announcement(&self, channel_id: u64)->bool{
		match self.sync_status {
			InitSyncTracker::NoSyncRequested => true,
			InitSyncTracker::ChannelsSyncing(i) => i < channel_id,
			InitSyncTracker::NodesSyncing(_) => true,
		}
	}

	/// Similar to the above, but for node announcements indexed by node_id.
	fn should_forward_node_announcement(&self, node_id: PublicKey) -> bool {
		match self.sync_status {
			InitSyncTracker::NoSyncRequested => true,
			InitSyncTracker::ChannelsSyncing(_) => false,
			InitSyncTracker::NodesSyncing(pk) => pk < node_id,
		}
	}
}

struct PeerHolder<Descriptor: SocketDescriptor> {
	peers: HashMap<Descriptor, Peer>,
	/// Only add to this set when noise completes:
	node_id_to_descriptor: HashMap<PublicKey, Descriptor>,
}

/// SimpleArcPeerManager is useful when you need a PeerManager 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
/// SimpleRefPeerManager is the more appropriate type. Defining these type aliases prevents
/// issues such as overly long function definitions.
pub type SimpleArcPeerManager<SD, M, T, F, C, L> = PeerManager<SD, Arc<SimpleArcChannelManager<M, T, F, L>>, Arc<NetGraphMsgHandler<Arc<NetworkGraph>, Arc<C>, Arc<L>>>, Arc<L>, Arc<IgnoringMessageHandler>>;

/// SimpleRefPeerManager is a type alias for a PeerManager reference, and is the reference
/// counterpart to the SimpleArcPeerManager type alias. Use this type by default when you don't
/// need a PeerManager 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.
pub type SimpleRefPeerManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, SD, M, T, F, C, L> = PeerManager<SD, SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, M, T, F, L>, &'e NetGraphMsgHandler<&'g NetworkGraph, &'h C, &'f L>, &'f L, IgnoringMessageHandler>;

/// A PeerManager manages a set of peers, described by their [`SocketDescriptor`] and marshalls
/// socket events into messages which it passes on to its [`MessageHandler`].
///
/// Locks are taken internally, so you must never assume that reentrancy from a
/// [`SocketDescriptor`] call back into [`PeerManager`] methods will not deadlock.
///
/// Calls to [`read_event`] will decode relevant messages and pass them to the
/// [`ChannelMessageHandler`], likely doing message processing in-line. Thus, the primary form of
/// parallelism in Rust-Lightning is in calls to [`read_event`]. Note, however, that calls to any
/// [`PeerManager`] functions related to the same connection must occur only in serial, making new
/// calls only after previous ones have returned.
///
/// Rather than using a plain PeerManager, it is preferable to use either a SimpleArcPeerManager
/// a SimpleRefPeerManager, for conciseness. See their documentation for more details, but
/// essentially you should default to using a SimpleRefPeerManager, and use a
/// SimpleArcPeerManager when you require a PeerManager with a static lifetime, such as when
/// you're using lightning-net-tokio.
///
/// [`read_event`]: PeerManager::read_event
pub struct PeerManager<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> where
		CM::Target: ChannelMessageHandler,
		RM::Target: RoutingMessageHandler,
		L::Target: Logger,
		CMH::Target: CustomMessageHandler {
	message_handler: MessageHandler<CM, RM>,
	peers: Mutex<PeerHolder<Descriptor>>,
	our_node_secret: SecretKey,
	ephemeral_key_midstate: Sha256Engine,
	custom_message_handler: CMH,

	peer_counter: AtomicCounter,

	logger: L,
}

enum MessageHandlingError {
	PeerHandleError(PeerHandleError),
	LightningError(LightningError),
}

impl From<PeerHandleError> for MessageHandlingError {
	fn from(error: PeerHandleError) -> Self {
		MessageHandlingError::PeerHandleError(error)
	}
}

impl From<LightningError> for MessageHandlingError {
	fn from(error: LightningError) -> Self {
		MessageHandlingError::LightningError(error)
	}
}

macro_rules! encode_msg {
	($msg: expr) => {{
		let mut buffer = VecWriter(Vec::new());
		wire::write($msg, &mut buffer).unwrap();
		buffer.0
	}}
}

impl<Descriptor: SocketDescriptor, CM: Deref, L: Deref> PeerManager<Descriptor, CM, IgnoringMessageHandler, L, IgnoringMessageHandler> where
		CM::Target: ChannelMessageHandler,
		L::Target: Logger {
	/// Constructs a new PeerManager with the given ChannelMessageHandler. No routing message
	/// handler is used and network graph messages are ignored.
	///
	/// ephemeral_random_data is used to derive per-connection ephemeral keys and must be
	/// cryptographically secure random bytes.
	///
	/// (C-not exported) as we can't export a PeerManager with a dummy route handler
	pub fn new_channel_only(channel_message_handler: CM, our_node_secret: SecretKey, ephemeral_random_data: &[u8; 32], logger: L) -> Self {
		Self::new(MessageHandler {
			chan_handler: channel_message_handler,
			route_handler: IgnoringMessageHandler{},
		}, our_node_secret, ephemeral_random_data, logger, IgnoringMessageHandler{})
	}
}

impl<Descriptor: SocketDescriptor, RM: Deref, L: Deref> PeerManager<Descriptor, ErroringMessageHandler, RM, L, IgnoringMessageHandler> where
		RM::Target: RoutingMessageHandler,
		L::Target: Logger {
	/// Constructs a new PeerManager with the given RoutingMessageHandler. No channel message
	/// handler is used and messages related to channels will be ignored (or generate error
	/// messages). Note that some other lightning implementations time-out connections after some
	/// time if no channel is built with the peer.
	///
	/// ephemeral_random_data is used to derive per-connection ephemeral keys and must be
	/// cryptographically secure random bytes.
	///
	/// (C-not exported) as we can't export a PeerManager with a dummy channel handler
	pub fn new_routing_only(routing_message_handler: RM, our_node_secret: SecretKey, ephemeral_random_data: &[u8; 32], logger: L) -> Self {
		Self::new(MessageHandler {
			chan_handler: ErroringMessageHandler::new(),
			route_handler: routing_message_handler,
		}, our_node_secret, ephemeral_random_data, logger, IgnoringMessageHandler{})
	}
}

/// A simple wrapper that optionally prints " from <pubkey>" for an optional pubkey.
/// This works around `format!()` taking a reference to each argument, preventing
/// `if let Some(node_id) = peer.their_node_id { format!(.., node_id) } else { .. }` from compiling
/// due to lifetime errors.
struct OptionalFromDebugger<'a>(&'a Option<PublicKey>);
impl core::fmt::Display for OptionalFromDebugger<'_> {
	fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> Result<(), core::fmt::Error> {
		if let Some(node_id) = self.0 { write!(f, " from {}", log_pubkey!(node_id)) } else { Ok(()) }
	}
}

impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> PeerManager<Descriptor, CM, RM, L, CMH> where
		CM::Target: ChannelMessageHandler,
		RM::Target: RoutingMessageHandler,
		L::Target: Logger,
		CMH::Target: CustomMessageHandler {
	/// Constructs a new PeerManager with the given message handlers and node_id secret key
	/// ephemeral_random_data is used to derive per-connection ephemeral keys and must be
	/// cryptographically secure random bytes.
	pub fn new(message_handler: MessageHandler<CM, RM>, our_node_secret: SecretKey, ephemeral_random_data: &[u8; 32], logger: L, custom_message_handler: CMH) -> Self {
		let mut ephemeral_key_midstate = Sha256::engine();
		ephemeral_key_midstate.input(ephemeral_random_data);

		PeerManager {
			message_handler,
			peers: Mutex::new(PeerHolder {
				peers: HashMap::new(),
				node_id_to_descriptor: HashMap::new()
			}),
			our_node_secret,
			ephemeral_key_midstate,
			peer_counter: AtomicCounter::new(),
			logger,
			custom_message_handler,
		}
	}

	/// Get the list of node ids for peers which have completed the initial handshake.
	///
	/// For outbound connections, this will be the same as the their_node_id parameter passed in to
	/// new_outbound_connection, however entries will only appear once the initial handshake has
	/// completed and we are sure the remote peer has the private key for the given node_id.
	pub fn get_peer_node_ids(&self) -> Vec<PublicKey> {
		let peers = self.peers.lock().unwrap();
		peers.peers.values().filter_map(|p| {
			if !p.channel_encryptor.is_ready_for_encryption() || p.their_features.is_none() {
				return None;
			}
			p.their_node_id
		}).collect()
	}

	fn get_ephemeral_key(&self) -> SecretKey {
		let mut ephemeral_hash = self.ephemeral_key_midstate.clone();
		let counter = self.peer_counter.get_increment();
		ephemeral_hash.input(&counter.to_le_bytes());
		SecretKey::from_slice(&Sha256::from_engine(ephemeral_hash).into_inner()).expect("You broke SHA-256!")
	}

	/// Indicates a new outbound connection has been established to a node with the given node_id.
	/// Note that if an Err is returned here you MUST NOT call socket_disconnected for the new
	/// descriptor but must disconnect the connection immediately.
	///
	/// Returns a small number of bytes to send to the remote node (currently always 50).
	///
	/// Panics if descriptor is duplicative with some other descriptor which has not yet been
	/// [`socket_disconnected()`].
	///
	/// [`socket_disconnected()`]: PeerManager::socket_disconnected
	pub fn new_outbound_connection(&self, their_node_id: PublicKey, descriptor: Descriptor) -> Result<Vec<u8>, PeerHandleError> {
		let mut peer_encryptor = PeerChannelEncryptor::new_outbound(their_node_id.clone(), self.get_ephemeral_key());
		let res = peer_encryptor.get_act_one().to_vec();
		let pending_read_buffer = [0; 50].to_vec(); // Noise act two is 50 bytes

		let mut peers = self.peers.lock().unwrap();
		if peers.peers.insert(descriptor, Peer {
			channel_encryptor: peer_encryptor,
			their_node_id: None,
			their_features: None,

			pending_outbound_buffer: LinkedList::new(),
			pending_outbound_buffer_first_msg_offset: 0,
			awaiting_write_event: false,

			pending_read_buffer,
			pending_read_buffer_pos: 0,
			pending_read_is_header: false,

			sync_status: InitSyncTracker::NoSyncRequested,

			msgs_sent_since_pong: 0,
			awaiting_pong_timer_tick_intervals: 0,
			received_message_since_timer_tick: false,
		}).is_some() {
			panic!("PeerManager driver duplicated descriptors!");
		};
		Ok(res)
	}

	/// Indicates a new inbound connection has been established.
	///
	/// May refuse the connection by returning an Err, but will never write bytes to the remote end
	/// (outbound connector always speaks first). Note that if an Err is returned here you MUST NOT
	/// call socket_disconnected for the new descriptor but must disconnect the connection
	/// immediately.
	///
	/// Panics if descriptor is duplicative with some other descriptor which has not yet been
	/// [`socket_disconnected()`].
	///
	/// [`socket_disconnected()`]: PeerManager::socket_disconnected
	pub fn new_inbound_connection(&self, descriptor: Descriptor) -> Result<(), PeerHandleError> {
		let peer_encryptor = PeerChannelEncryptor::new_inbound(&self.our_node_secret);
		let pending_read_buffer = [0; 50].to_vec(); // Noise act one is 50 bytes

		let mut peers = self.peers.lock().unwrap();
		if peers.peers.insert(descriptor, Peer {
			channel_encryptor: peer_encryptor,
			their_node_id: None,
			their_features: None,

			pending_outbound_buffer: LinkedList::new(),
			pending_outbound_buffer_first_msg_offset: 0,
			awaiting_write_event: false,

			pending_read_buffer,
			pending_read_buffer_pos: 0,
			pending_read_is_header: false,

			sync_status: InitSyncTracker::NoSyncRequested,

			msgs_sent_since_pong: 0,
			awaiting_pong_timer_tick_intervals: 0,
			received_message_since_timer_tick: false,
		}).is_some() {
			panic!("PeerManager driver duplicated descriptors!");
		};
		Ok(())
	}

	fn do_attempt_write_data(&self, descriptor: &mut Descriptor, peer: &mut Peer) {
		while !peer.awaiting_write_event {
			if peer.pending_outbound_buffer.len() < OUTBOUND_BUFFER_LIMIT_READ_PAUSE && peer.msgs_sent_since_pong < BUFFER_DRAIN_MSGS_PER_TICK {
				match peer.sync_status {
					InitSyncTracker::NoSyncRequested => {},
					InitSyncTracker::ChannelsSyncing(c) if c < 0xffff_ffff_ffff_ffff => {
						let steps = ((OUTBOUND_BUFFER_LIMIT_READ_PAUSE - peer.pending_outbound_buffer.len() + 2) / 3) as u8;
						let all_messages = self.message_handler.route_handler.get_next_channel_announcements(c, steps);
						for &(ref announce, ref update_a_option, ref update_b_option) in all_messages.iter() {
							self.enqueue_message(peer, announce);
							if let &Some(ref update_a) = update_a_option {
								self.enqueue_message(peer, update_a);
							}
							if let &Some(ref update_b) = update_b_option {
								self.enqueue_message(peer, update_b);
							}
							peer.sync_status = InitSyncTracker::ChannelsSyncing(announce.contents.short_channel_id + 1);
						}
						if all_messages.is_empty() || all_messages.len() != steps as usize {
							peer.sync_status = InitSyncTracker::ChannelsSyncing(0xffff_ffff_ffff_ffff);
						}
					},
					InitSyncTracker::ChannelsSyncing(c) if c == 0xffff_ffff_ffff_ffff => {
						let steps = (OUTBOUND_BUFFER_LIMIT_READ_PAUSE - peer.pending_outbound_buffer.len()) as u8;
						let all_messages = self.message_handler.route_handler.get_next_node_announcements(None, steps);
						for msg in all_messages.iter() {
							self.enqueue_message(peer, msg);
							peer.sync_status = InitSyncTracker::NodesSyncing(msg.contents.node_id);
						}
						if all_messages.is_empty() || all_messages.len() != steps as usize {
							peer.sync_status = InitSyncTracker::NoSyncRequested;
						}
					},
					InitSyncTracker::ChannelsSyncing(_) => unreachable!(),
					InitSyncTracker::NodesSyncing(key) => {
						let steps = (OUTBOUND_BUFFER_LIMIT_READ_PAUSE - peer.pending_outbound_buffer.len()) as u8;
						let all_messages = self.message_handler.route_handler.get_next_node_announcements(Some(&key), steps);
						for msg in all_messages.iter() {
							self.enqueue_message(peer, msg);
							peer.sync_status = InitSyncTracker::NodesSyncing(msg.contents.node_id);
						}
						if all_messages.is_empty() || all_messages.len() != steps as usize {
							peer.sync_status = InitSyncTracker::NoSyncRequested;
						}
					},
				}
			}
			if peer.msgs_sent_since_pong >= BUFFER_DRAIN_MSGS_PER_TICK {
				self.maybe_send_extra_ping(peer);
			}

			if {
				let next_buff = match peer.pending_outbound_buffer.front() {
					None => return,
					Some(buff) => buff,
				};

				let should_be_reading = peer.pending_outbound_buffer.len() < OUTBOUND_BUFFER_LIMIT_READ_PAUSE;
				let pending = &next_buff[peer.pending_outbound_buffer_first_msg_offset..];
				let data_sent = descriptor.send_data(pending, should_be_reading);
				peer.pending_outbound_buffer_first_msg_offset += data_sent;
				if peer.pending_outbound_buffer_first_msg_offset == next_buff.len() { true } else { false }
			} {
				peer.pending_outbound_buffer_first_msg_offset = 0;
				peer.pending_outbound_buffer.pop_front();
			} else {
				peer.awaiting_write_event = true;
			}
		}
	}

	/// Indicates that there is room to write data to the given socket descriptor.
	///
	/// May return an Err to indicate that the connection should be closed.
	///
	/// May call [`send_data`] on the descriptor passed in (or an equal descriptor) before
	/// returning. Thus, be very careful with reentrancy issues! The invariants around calling
	/// [`write_buffer_space_avail`] in case a write did not fully complete must still hold - be
	/// ready to call `[write_buffer_space_avail`] again if a write call generated here isn't
	/// sufficient!
	///
	/// [`send_data`]: SocketDescriptor::send_data
	/// [`write_buffer_space_avail`]: PeerManager::write_buffer_space_avail
	pub fn write_buffer_space_avail(&self, descriptor: &mut Descriptor) -> Result<(), PeerHandleError> {
		let mut peers = self.peers.lock().unwrap();
		match peers.peers.get_mut(descriptor) {
			None => {
				// This is most likely a simple race condition where the user found that the socket
				// was writeable, then we told the user to `disconnect_socket()`, then they called
				// this method. Return an error to make sure we get disconnected.
				return Err(PeerHandleError { no_connection_possible: false });
			},
			Some(peer) => {
				peer.awaiting_write_event = false;
				self.do_attempt_write_data(descriptor, peer);
			}
		};
		Ok(())
	}

	/// Indicates that data was read from the given socket descriptor.
	///
	/// May return an Err to indicate that the connection should be closed.
	///
	/// Will *not* call back into [`send_data`] on any descriptors to avoid reentrancy complexity.
	/// Thus, however, you should call [`process_events`] after any `read_event` to generate
	/// [`send_data`] calls to handle responses.
	///
	/// If `Ok(true)` is returned, further read_events should not be triggered until a
	/// [`send_data`] call on this descriptor has `resume_read` set (preventing DoS issues in the
	/// send buffer).
	///
	/// [`send_data`]: SocketDescriptor::send_data
	/// [`process_events`]: PeerManager::process_events
	pub fn read_event(&self, peer_descriptor: &mut Descriptor, data: &[u8]) -> Result<bool, PeerHandleError> {
		match self.do_read_event(peer_descriptor, data) {
			Ok(res) => Ok(res),
			Err(e) => {
				log_trace!(self.logger, "Peer sent invalid data or we decided to disconnect due to a protocol error");
				self.disconnect_event_internal(peer_descriptor, e.no_connection_possible);
				Err(e)
			}
		}
	}

	/// Append a message to a peer's pending outbound/write buffer
	fn enqueue_encoded_message(&self, peer: &mut Peer, encoded_message: &Vec<u8>) {
		peer.msgs_sent_since_pong += 1;
		peer.pending_outbound_buffer.push_back(peer.channel_encryptor.encrypt_message(&encoded_message[..]));
	}

	/// Append a message to a peer's pending outbound/write buffer
	fn enqueue_message<M: wire::Type>(&self, peer: &mut Peer, message: &M) {
		let mut buffer = VecWriter(Vec::with_capacity(2048));
		wire::write(message, &mut buffer).unwrap(); // crash if the write failed

		if is_gossip_msg(message.type_id()) {
			log_gossip!(self.logger, "Enqueueing message {:?} to {}", message, log_pubkey!(peer.their_node_id.unwrap()));
		} else {
			log_trace!(self.logger, "Enqueueing message {:?} to {}", message, log_pubkey!(peer.their_node_id.unwrap()))
		}
		self.enqueue_encoded_message(peer, &buffer.0);
	}

	fn do_read_event(&self, peer_descriptor: &mut Descriptor, data: &[u8]) -> Result<bool, PeerHandleError> {
		let pause_read = {
			let mut peers_lock = self.peers.lock().unwrap();
			let peers = &mut *peers_lock;
			let mut msgs_to_forward = Vec::new();
			let mut peer_node_id = None;
			let pause_read = match peers.peers.get_mut(peer_descriptor) {
				None => {
					// This is most likely a simple race condition where the user read some bytes
					// from the socket, then we told the user to `disconnect_socket()`, then they
					// called this method. Return an error to make sure we get disconnected.
					return Err(PeerHandleError { no_connection_possible: false });
				},
				Some(peer) => {
					assert!(peer.pending_read_buffer.len() > 0);
					assert!(peer.pending_read_buffer.len() > peer.pending_read_buffer_pos);

					let mut read_pos = 0;
					while read_pos < data.len() {
						{
							let data_to_copy = cmp::min(peer.pending_read_buffer.len() - peer.pending_read_buffer_pos, data.len() - read_pos);
							peer.pending_read_buffer[peer.pending_read_buffer_pos..peer.pending_read_buffer_pos + data_to_copy].copy_from_slice(&data[read_pos..read_pos + data_to_copy]);
							read_pos += data_to_copy;
							peer.pending_read_buffer_pos += data_to_copy;
						}

						if peer.pending_read_buffer_pos == peer.pending_read_buffer.len() {
							peer.pending_read_buffer_pos = 0;

							macro_rules! try_potential_handleerror {
								($thing: expr) => {
									match $thing {
										Ok(x) => x,
										Err(e) => {
											match e.action {
												msgs::ErrorAction::DisconnectPeer { msg: _ } => {
													//TODO: Try to push msg
													log_debug!(self.logger, "Error handling message{}; disconnecting peer with: {}", OptionalFromDebugger(&peer.their_node_id), e.err);
													return Err(PeerHandleError{ no_connection_possible: false });
												},
												msgs::ErrorAction::IgnoreAndLog(level) => {
													log_given_level!(self.logger, level, "Error handling message{}; ignoring: {}", OptionalFromDebugger(&peer.their_node_id), e.err);
													continue
												},
												msgs::ErrorAction::IgnoreError => {
													log_debug!(self.logger, "Error handling message{}; ignoring: {}", OptionalFromDebugger(&peer.their_node_id), e.err);
													continue;
												},
												msgs::ErrorAction::SendErrorMessage { msg } => {
													log_debug!(self.logger, "Error handling message{}; sending error message with: {}", OptionalFromDebugger(&peer.their_node_id), e.err);
													self.enqueue_message(peer, &msg);
													continue;
												},
											}
										}
									}
								}
							}

							macro_rules! insert_node_id {
								() => {
									match peers.node_id_to_descriptor.entry(peer.their_node_id.unwrap()) {
										hash_map::Entry::Occupied(_) => {
											log_trace!(self.logger, "Got second connection with {}, closing", log_pubkey!(peer.their_node_id.unwrap()));
											peer.their_node_id = None; // Unset so that we don't generate a peer_disconnected event
											return Err(PeerHandleError{ no_connection_possible: false })
										},
										hash_map::Entry::Vacant(entry) => {
											log_debug!(self.logger, "Finished noise handshake for connection with {}", log_pubkey!(peer.their_node_id.unwrap()));
											entry.insert(peer_descriptor.clone())
										},
									};
								}
							}

							let next_step = peer.channel_encryptor.get_noise_step();
							match next_step {
								NextNoiseStep::ActOne => {
									let act_two = try_potential_handleerror!(peer.channel_encryptor.process_act_one_with_keys(&peer.pending_read_buffer[..], &self.our_node_secret, self.get_ephemeral_key())).to_vec();
									peer.pending_outbound_buffer.push_back(act_two);
									peer.pending_read_buffer = [0; 66].to_vec(); // act three is 66 bytes long
								},
								NextNoiseStep::ActTwo => {
									let (act_three, their_node_id) = try_potential_handleerror!(peer.channel_encryptor.process_act_two(&peer.pending_read_buffer[..], &self.our_node_secret));
									peer.pending_outbound_buffer.push_back(act_three.to_vec());
									peer.pending_read_buffer = [0; 18].to_vec(); // Message length header is 18 bytes
									peer.pending_read_is_header = true;

									peer.their_node_id = Some(their_node_id);
									insert_node_id!();
									let features = InitFeatures::known();
									let resp = msgs::Init { features };
									self.enqueue_message(peer, &resp);
									peer.awaiting_pong_timer_tick_intervals = 0;
								},
								NextNoiseStep::ActThree => {
									let their_node_id = try_potential_handleerror!(peer.channel_encryptor.process_act_three(&peer.pending_read_buffer[..]));
									peer.pending_read_buffer = [0; 18].to_vec(); // Message length header is 18 bytes
									peer.pending_read_is_header = true;
									peer.their_node_id = Some(their_node_id);
									insert_node_id!();
									let features = InitFeatures::known();
									let resp = msgs::Init { features };
									self.enqueue_message(peer, &resp);
									peer.awaiting_pong_timer_tick_intervals = 0;
								},
								NextNoiseStep::NoiseComplete => {
									if peer.pending_read_is_header {
										let msg_len = try_potential_handleerror!(peer.channel_encryptor.decrypt_length_header(&peer.pending_read_buffer[..]));
										peer.pending_read_buffer = Vec::with_capacity(msg_len as usize + 16);
										peer.pending_read_buffer.resize(msg_len as usize + 16, 0);
										if msg_len < 2 { // Need at least the message type tag
											return Err(PeerHandleError{ no_connection_possible: false });
										}
										peer.pending_read_is_header = false;
									} else {
										let msg_data = try_potential_handleerror!(peer.channel_encryptor.decrypt_message(&peer.pending_read_buffer[..]));
										assert!(msg_data.len() >= 2);

										// Reset read buffer
										peer.pending_read_buffer = [0; 18].to_vec();
										peer.pending_read_is_header = true;

										let mut reader = io::Cursor::new(&msg_data[..]);
										let message_result = wire::read(&mut reader, &*self.custom_message_handler);
										let message = match message_result {
											Ok(x) => x,
											Err(e) => {
												match e {
													msgs::DecodeError::UnknownVersion => return Err(PeerHandleError { no_connection_possible: false }),
													msgs::DecodeError::UnknownRequiredFeature => {
														log_gossip!(self.logger, "Got a channel/node announcement with an unknown required feature flag, you may want to update!");
														continue;
													}
													msgs::DecodeError::InvalidValue => {
														log_debug!(self.logger, "Got an invalid value while deserializing message");
														return Err(PeerHandleError { no_connection_possible: false });
													}
													msgs::DecodeError::ShortRead => {
														log_debug!(self.logger, "Deserialization failed due to shortness of message");
														return Err(PeerHandleError { no_connection_possible: false });
													}
													msgs::DecodeError::BadLengthDescriptor => return Err(PeerHandleError { no_connection_possible: false }),
													msgs::DecodeError::Io(_) => return Err(PeerHandleError { no_connection_possible: false }),
													msgs::DecodeError::UnsupportedCompression => {
														log_gossip!(self.logger, "We don't support zlib-compressed message fields, ignoring message");
														continue;
													}
												}
											}
										};

										match self.handle_message(peer, message) {
											Err(handling_error) => match handling_error {
												MessageHandlingError::PeerHandleError(e) => { return Err(e) },
												MessageHandlingError::LightningError(e) => {
													try_potential_handleerror!(Err(e));
												},
											},
											Ok(Some(msg)) => {
												peer_node_id = Some(peer.their_node_id.expect("After noise is complete, their_node_id is always set"));
												msgs_to_forward.push(msg);
											},
											Ok(None) => {},
										}
									}
								}
							}
						}
					}

					peer.pending_outbound_buffer.len() > OUTBOUND_BUFFER_LIMIT_READ_PAUSE // pause_read
				}
			};

			for msg in msgs_to_forward.drain(..) {
				self.forward_broadcast_msg(peers, &msg, peer_node_id.as_ref());
			}

			pause_read
		};

		Ok(pause_read)
	}

	/// Process an incoming message and return a decision (ok, lightning error, peer handling error) regarding the next action with the peer
	/// Returns the message back if it needs to be broadcasted to all other peers.
	fn handle_message(
		&self,
		peer: &mut Peer,
		message: wire::Message<<<CMH as core::ops::Deref>::Target as wire::CustomMessageReader>::CustomMessage>
	) -> Result<Option<wire::Message<<<CMH as core::ops::Deref>::Target as wire::CustomMessageReader>::CustomMessage>>, MessageHandlingError> {
		if is_gossip_msg(message.type_id()) {
			log_gossip!(self.logger, "Received message {:?} from {}", message, log_pubkey!(peer.their_node_id.unwrap()));
		} else {
			log_trace!(self.logger, "Received message {:?} from {}", message, log_pubkey!(peer.their_node_id.unwrap()));
		}

		peer.received_message_since_timer_tick = true;

		// Need an Init as first message
		if let wire::Message::Init(_) = message {
		} else if peer.their_features.is_none() {
			log_debug!(self.logger, "Peer {} sent non-Init first message", log_pubkey!(peer.their_node_id.unwrap()));
			return Err(PeerHandleError{ no_connection_possible: false }.into());
		}

		let mut should_forward = None;

		match message {
			// Setup and Control messages:
			wire::Message::Init(msg) => {
				if msg.features.requires_unknown_bits() {
					log_debug!(self.logger, "Peer features required unknown version bits");
					return Err(PeerHandleError{ no_connection_possible: true }.into());
				}
				if peer.their_features.is_some() {
					return Err(PeerHandleError{ no_connection_possible: false }.into());
				}

				log_info!(self.logger, "Received peer Init message from {}: {}", log_pubkey!(peer.their_node_id.unwrap()), msg.features);

				if msg.features.initial_routing_sync() {
					peer.sync_status = InitSyncTracker::ChannelsSyncing(0);
				}
				if !msg.features.supports_static_remote_key() {
					log_debug!(self.logger, "Peer {} does not support static remote key, disconnecting with no_connection_possible", log_pubkey!(peer.their_node_id.unwrap()));
					return Err(PeerHandleError{ no_connection_possible: true }.into());
				}

				self.message_handler.route_handler.sync_routing_table(&peer.their_node_id.unwrap(), &msg);

				self.message_handler.chan_handler.peer_connected(&peer.their_node_id.unwrap(), &msg);
				peer.their_features = Some(msg.features);
			},
			wire::Message::Error(msg) => {
				let mut data_is_printable = true;
				for b in msg.data.bytes() {
					if b < 32 || b > 126 {
						data_is_printable = false;
						break;
					}
				}

				if data_is_printable {
					log_debug!(self.logger, "Got Err message from {}: {}", log_pubkey!(peer.their_node_id.unwrap()), msg.data);
				} else {
					log_debug!(self.logger, "Got Err message from {} with non-ASCII error message", log_pubkey!(peer.their_node_id.unwrap()));
				}
				self.message_handler.chan_handler.handle_error(&peer.their_node_id.unwrap(), &msg);
				if msg.channel_id == [0; 32] {
					return Err(PeerHandleError{ no_connection_possible: true }.into());
				}
			},

			wire::Message::Ping(msg) => {
				if msg.ponglen < 65532 {
					let resp = msgs::Pong { byteslen: msg.ponglen };
					self.enqueue_message(peer, &resp);
				}
			},
			wire::Message::Pong(_msg) => {
				peer.awaiting_pong_timer_tick_intervals = 0;
				peer.msgs_sent_since_pong = 0;
			},

			// Channel messages:
			wire::Message::OpenChannel(msg) => {
				self.message_handler.chan_handler.handle_open_channel(&peer.their_node_id.unwrap(), peer.their_features.clone().unwrap(), &msg);
			},
			wire::Message::AcceptChannel(msg) => {
				self.message_handler.chan_handler.handle_accept_channel(&peer.their_node_id.unwrap(), peer.their_features.clone().unwrap(), &msg);
			},

			wire::Message::FundingCreated(msg) => {
				self.message_handler.chan_handler.handle_funding_created(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::FundingSigned(msg) => {
				self.message_handler.chan_handler.handle_funding_signed(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::FundingLocked(msg) => {
				self.message_handler.chan_handler.handle_funding_locked(&peer.their_node_id.unwrap(), &msg);
			},

			wire::Message::Shutdown(msg) => {
				self.message_handler.chan_handler.handle_shutdown(&peer.their_node_id.unwrap(), peer.their_features.as_ref().unwrap(), &msg);
			},
			wire::Message::ClosingSigned(msg) => {
				self.message_handler.chan_handler.handle_closing_signed(&peer.their_node_id.unwrap(), &msg);
			},

			// Commitment messages:
			wire::Message::UpdateAddHTLC(msg) => {
				self.message_handler.chan_handler.handle_update_add_htlc(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::UpdateFulfillHTLC(msg) => {
				self.message_handler.chan_handler.handle_update_fulfill_htlc(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::UpdateFailHTLC(msg) => {
				self.message_handler.chan_handler.handle_update_fail_htlc(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::UpdateFailMalformedHTLC(msg) => {
				self.message_handler.chan_handler.handle_update_fail_malformed_htlc(&peer.their_node_id.unwrap(), &msg);
			},

			wire::Message::CommitmentSigned(msg) => {
				self.message_handler.chan_handler.handle_commitment_signed(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::RevokeAndACK(msg) => {
				self.message_handler.chan_handler.handle_revoke_and_ack(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::UpdateFee(msg) => {
				self.message_handler.chan_handler.handle_update_fee(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::ChannelReestablish(msg) => {
				self.message_handler.chan_handler.handle_channel_reestablish(&peer.their_node_id.unwrap(), &msg);
			},

			// Routing messages:
			wire::Message::AnnouncementSignatures(msg) => {
				self.message_handler.chan_handler.handle_announcement_signatures(&peer.their_node_id.unwrap(), &msg);
			},
			wire::Message::ChannelAnnouncement(msg) => {
				if self.message_handler.route_handler.handle_channel_announcement(&msg)
						.map_err(|e| -> MessageHandlingError { e.into() })? {
					should_forward = Some(wire::Message::ChannelAnnouncement(msg));
				}
			},
			wire::Message::NodeAnnouncement(msg) => {
				if self.message_handler.route_handler.handle_node_announcement(&msg)
						.map_err(|e| -> MessageHandlingError { e.into() })? {
					should_forward = Some(wire::Message::NodeAnnouncement(msg));
				}
			},
			wire::Message::ChannelUpdate(msg) => {
				self.message_handler.chan_handler.handle_channel_update(&peer.their_node_id.unwrap(), &msg);
				if self.message_handler.route_handler.handle_channel_update(&msg)
						.map_err(|e| -> MessageHandlingError { e.into() })? {
					should_forward = Some(wire::Message::ChannelUpdate(msg));
				}
			},
			wire::Message::QueryShortChannelIds(msg) => {
				self.message_handler.route_handler.handle_query_short_channel_ids(&peer.their_node_id.unwrap(), msg)?;
			},
			wire::Message::ReplyShortChannelIdsEnd(msg) => {
				self.message_handler.route_handler.handle_reply_short_channel_ids_end(&peer.their_node_id.unwrap(), msg)?;
			},
			wire::Message::QueryChannelRange(msg) => {
				self.message_handler.route_handler.handle_query_channel_range(&peer.their_node_id.unwrap(), msg)?;
			},
			wire::Message::ReplyChannelRange(msg) => {
				self.message_handler.route_handler.handle_reply_channel_range(&peer.their_node_id.unwrap(), msg)?;
			},
			wire::Message::GossipTimestampFilter(_msg) => {
				// TODO: handle message
			},

			// Unknown messages:
			wire::Message::Unknown(type_id) if message.is_even() => {
				log_debug!(self.logger, "Received unknown even message of type {}, disconnecting peer!", type_id);
				// Fail the channel if message is an even, unknown type as per BOLT #1.
				return Err(PeerHandleError{ no_connection_possible: true }.into());
			},
			wire::Message::Unknown(type_id) => {
				log_trace!(self.logger, "Received unknown odd message of type {}, ignoring", type_id);
			},
			wire::Message::Custom(custom) => {
				self.custom_message_handler.handle_custom_message(custom, &peer.their_node_id.unwrap())?;
			},
		};
		Ok(should_forward)
	}

	fn forward_broadcast_msg(&self, peers: &mut PeerHolder<Descriptor>, msg: &wire::Message<<<CMH as core::ops::Deref>::Target as wire::CustomMessageReader>::CustomMessage>, except_node: Option<&PublicKey>) {
		match msg {
			wire::Message::ChannelAnnouncement(ref msg) => {
				log_gossip!(self.logger, "Sending message to all peers except {:?} or the announced channel's counterparties: {:?}", except_node, msg);
				let encoded_msg = encode_msg!(msg);

				for (_, peer) in peers.peers.iter_mut() {
					if !peer.channel_encryptor.is_ready_for_encryption() || peer.their_features.is_none() ||
							!peer.should_forward_channel_announcement(msg.contents.short_channel_id) {
						continue
					}
					if peer.pending_outbound_buffer.len() > OUTBOUND_BUFFER_LIMIT_DROP_GOSSIP
						|| peer.msgs_sent_since_pong > BUFFER_DRAIN_MSGS_PER_TICK * FORWARD_INIT_SYNC_BUFFER_LIMIT_RATIO
					{
						log_gossip!(self.logger, "Skipping broadcast message to {:?} as its outbound buffer is full", peer.their_node_id);
						continue;
					}
					if peer.their_node_id.as_ref() == Some(&msg.contents.node_id_1) ||
					   peer.their_node_id.as_ref() == Some(&msg.contents.node_id_2) {
						continue;
					}
					if except_node.is_some() && peer.their_node_id.as_ref() == except_node {
						continue;
					}
					self.enqueue_encoded_message(peer, &encoded_msg);
				}
			},
			wire::Message::NodeAnnouncement(ref msg) => {
				log_gossip!(self.logger, "Sending message to all peers except {:?} or the announced node: {:?}", except_node, msg);
				let encoded_msg = encode_msg!(msg);

				for (_, peer) in peers.peers.iter_mut() {
					if !peer.channel_encryptor.is_ready_for_encryption() || peer.their_features.is_none() ||
							!peer.should_forward_node_announcement(msg.contents.node_id) {
						continue
					}
					if peer.pending_outbound_buffer.len() > OUTBOUND_BUFFER_LIMIT_DROP_GOSSIP
						|| peer.msgs_sent_since_pong > BUFFER_DRAIN_MSGS_PER_TICK * FORWARD_INIT_SYNC_BUFFER_LIMIT_RATIO
					{
						log_gossip!(self.logger, "Skipping broadcast message to {:?} as its outbound buffer is full", peer.their_node_id);
						continue;
					}
					if peer.their_node_id.as_ref() == Some(&msg.contents.node_id) {
						continue;
					}
					if except_node.is_some() && peer.their_node_id.as_ref() == except_node {
						continue;
					}
					self.enqueue_encoded_message(peer, &encoded_msg);
				}
			},
			wire::Message::ChannelUpdate(ref msg) => {
				log_gossip!(self.logger, "Sending message to all peers except {:?}: {:?}", except_node, msg);
				let encoded_msg = encode_msg!(msg);

				for (_, peer) in peers.peers.iter_mut() {
					if !peer.channel_encryptor.is_ready_for_encryption() || peer.their_features.is_none() ||
							!peer.should_forward_channel_announcement(msg.contents.short_channel_id)  {
						continue
					}
					if peer.pending_outbound_buffer.len() > OUTBOUND_BUFFER_LIMIT_DROP_GOSSIP
						|| peer.msgs_sent_since_pong > BUFFER_DRAIN_MSGS_PER_TICK * FORWARD_INIT_SYNC_BUFFER_LIMIT_RATIO
					{
						log_gossip!(self.logger, "Skipping broadcast message to {:?} as its outbound buffer is full", peer.their_node_id);
						continue;
					}
					if except_node.is_some() && peer.their_node_id.as_ref() == except_node {
						continue;
					}
					self.enqueue_encoded_message(peer, &encoded_msg);
				}
			},
			_ => debug_assert!(false, "We shouldn't attempt to forward anything but gossip messages"),
		}
	}

	/// Checks for any events generated by our handlers and processes them. Includes sending most
	/// response messages as well as messages generated by calls to handler functions directly (eg
	/// functions like [`ChannelManager::process_pending_htlc_forwards`] or [`send_payment`]).
	///
	/// May call [`send_data`] on [`SocketDescriptor`]s. Thus, be very careful with reentrancy
	/// issues!
	///
	/// You don't have to call this function explicitly if you are using [`lightning-net-tokio`]
	/// or one of the other clients provided in our language bindings.
	///
	/// [`send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
	/// [`ChannelManager::process_pending_htlc_forwards`]: crate::ln::channelmanager::ChannelManager::process_pending_htlc_forwards
	/// [`send_data`]: SocketDescriptor::send_data
	pub fn process_events(&self) {
		{
			// TODO: There are some DoS attacks here where you can flood someone's outbound send
			// buffer by doing things like announcing channels on another node. We should be willing to
			// drop optional-ish messages when send buffers get full!

			let mut peers_lock = self.peers.lock().unwrap();
			let mut events_generated = self.message_handler.chan_handler.get_and_clear_pending_msg_events();
			events_generated.append(&mut self.message_handler.route_handler.get_and_clear_pending_msg_events());
			let peers = &mut *peers_lock;
			macro_rules! get_peer_for_forwarding {
				($node_id: expr) => {
					{
						match peers.node_id_to_descriptor.get($node_id) {
							Some(descriptor) => match peers.peers.get_mut(&descriptor) {
								Some(peer) => {
									if peer.their_features.is_none() {
										continue;
									}
									peer
								},
								None => panic!("Inconsistent peers set state!"),
							},
							None => {
								continue;
							},
						}
					}
				}
			}
			for event in events_generated.drain(..) {
				match event {
					MessageSendEvent::SendAcceptChannel { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendAcceptChannel event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.temporary_channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendOpenChannel { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendOpenChannel event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.temporary_channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendFundingCreated { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendFundingCreated event in peer_handler for node {} for channel {} (which becomes {})",
								log_pubkey!(node_id),
								log_bytes!(msg.temporary_channel_id),
								log_funding_channel_id!(msg.funding_txid, msg.funding_output_index));
						// TODO: If the peer is gone we should generate a DiscardFunding event
						// indicating to the wallet that they should just throw away this funding transaction
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendFundingSigned { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendFundingSigned event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendFundingLocked { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendFundingLocked event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendAnnouncementSignatures { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendAnnouncementSignatures event in peer_handler for node {} for channel {})",
								log_pubkey!(node_id),
								log_bytes!(msg.channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::UpdateHTLCs { ref node_id, updates: msgs::CommitmentUpdate { ref update_add_htlcs, ref update_fulfill_htlcs, ref update_fail_htlcs, ref update_fail_malformed_htlcs, ref update_fee, ref commitment_signed } } => {
						log_debug!(self.logger, "Handling UpdateHTLCs event in peer_handler for node {} with {} adds, {} fulfills, {} fails for channel {}",
								log_pubkey!(node_id),
								update_add_htlcs.len(),
								update_fulfill_htlcs.len(),
								update_fail_htlcs.len(),
								log_bytes!(commitment_signed.channel_id));
						let peer = get_peer_for_forwarding!(node_id);
						for msg in update_add_htlcs {
							self.enqueue_message(peer, msg);
						}
						for msg in update_fulfill_htlcs {
							self.enqueue_message(peer, msg);
						}
						for msg in update_fail_htlcs {
							self.enqueue_message(peer, msg);
						}
						for msg in update_fail_malformed_htlcs {
							self.enqueue_message(peer, msg);
						}
						if let &Some(ref msg) = update_fee {
							self.enqueue_message(peer, msg);
						}
						self.enqueue_message(peer, commitment_signed);
					},
					MessageSendEvent::SendRevokeAndACK { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendRevokeAndACK event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendClosingSigned { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendClosingSigned event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendShutdown { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling Shutdown event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendChannelReestablish { ref node_id, ref msg } => {
						log_debug!(self.logger, "Handling SendChannelReestablish event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id),
								log_bytes!(msg.channel_id));
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::BroadcastChannelAnnouncement { msg, update_msg } => {
						log_debug!(self.logger, "Handling BroadcastChannelAnnouncement event in peer_handler for short channel id {}", msg.contents.short_channel_id);
						if self.message_handler.route_handler.handle_channel_announcement(&msg).is_ok() && self.message_handler.route_handler.handle_channel_update(&update_msg).is_ok() {
							self.forward_broadcast_msg(peers, &wire::Message::ChannelAnnouncement(msg), None);
							self.forward_broadcast_msg(peers, &wire::Message::ChannelUpdate(update_msg), None);
						}
					},
					MessageSendEvent::BroadcastNodeAnnouncement { msg } => {
						log_debug!(self.logger, "Handling BroadcastNodeAnnouncement event in peer_handler");
						if self.message_handler.route_handler.handle_node_announcement(&msg).is_ok() {
							self.forward_broadcast_msg(peers, &wire::Message::NodeAnnouncement(msg), None);
						}
					},
					MessageSendEvent::BroadcastChannelUpdate { msg } => {
						log_debug!(self.logger, "Handling BroadcastChannelUpdate event in peer_handler for short channel id {}", msg.contents.short_channel_id);
						if self.message_handler.route_handler.handle_channel_update(&msg).is_ok() {
							self.forward_broadcast_msg(peers, &wire::Message::ChannelUpdate(msg), None);
						}
					},
					MessageSendEvent::SendChannelUpdate { ref node_id, ref msg } => {
						log_trace!(self.logger, "Handling SendChannelUpdate event in peer_handler for node {} for channel {}",
								log_pubkey!(node_id), msg.contents.short_channel_id);
						let peer = get_peer_for_forwarding!(node_id);
						peer.pending_outbound_buffer.push_back(peer.channel_encryptor.encrypt_message(&encode_msg!(msg)));
					},
					MessageSendEvent::HandleError { ref node_id, ref action } => {
						match *action {
							msgs::ErrorAction::DisconnectPeer { ref msg } => {
								if let Some(mut descriptor) = peers.node_id_to_descriptor.remove(node_id) {
									if let Some(mut peer) = peers.peers.remove(&descriptor) {
										if let Some(ref msg) = *msg {
											log_trace!(self.logger, "Handling DisconnectPeer HandleError event in peer_handler for node {} with message {}",
													log_pubkey!(node_id),
													msg.data);
											self.enqueue_message(&mut peer, msg);
											// This isn't guaranteed to work, but if there is enough free
											// room in the send buffer, put the error message there...
											self.do_attempt_write_data(&mut descriptor, &mut peer);
										} else {
											log_gossip!(self.logger, "Handling DisconnectPeer HandleError event in peer_handler for node {} with no message", log_pubkey!(node_id));
										}
									}
									descriptor.disconnect_socket();
									self.message_handler.chan_handler.peer_disconnected(&node_id, false);
								}
							},
							msgs::ErrorAction::IgnoreAndLog(level) => {
								log_given_level!(self.logger, level, "Received a HandleError event to be ignored for node {}", log_pubkey!(node_id));
							},
							msgs::ErrorAction::IgnoreError => {
								log_debug!(self.logger, "Received a HandleError event to be ignored for node {}", log_pubkey!(node_id));
							},
							msgs::ErrorAction::SendErrorMessage { ref msg } => {
								log_trace!(self.logger, "Handling SendErrorMessage HandleError event in peer_handler for node {} with message {}",
										log_pubkey!(node_id),
										msg.data);
								self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
							},
						}
					},
					MessageSendEvent::SendChannelRangeQuery { ref node_id, ref msg } => {
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					},
					MessageSendEvent::SendShortIdsQuery { ref node_id, ref msg } => {
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					}
					MessageSendEvent::SendReplyChannelRange { ref node_id, ref msg } => {
						log_gossip!(self.logger, "Handling SendReplyChannelRange event in peer_handler for node {} with num_scids={} first_blocknum={} number_of_blocks={}, sync_complete={}",
							log_pubkey!(node_id),
							msg.short_channel_ids.len(),
							msg.first_blocknum,
							msg.number_of_blocks,
							msg.sync_complete);
						self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
					}
				}
			}

			for (node_id, msg) in self.custom_message_handler.get_and_clear_pending_msg() {
				self.enqueue_message(get_peer_for_forwarding!(&node_id), &msg);
			}

			for (descriptor, peer) in peers.peers.iter_mut() {
				self.do_attempt_write_data(&mut (*descriptor).clone(), peer);
			}
		}
	}

	/// Indicates that the given socket descriptor's connection is now closed.
	pub fn socket_disconnected(&self, descriptor: &Descriptor) {
		self.disconnect_event_internal(descriptor, false);
	}

	fn disconnect_event_internal(&self, descriptor: &Descriptor, no_connection_possible: bool) {
		let mut peers = self.peers.lock().unwrap();
		let peer_option = peers.peers.remove(descriptor);
		match peer_option {
			None => {
				// This is most likely a simple race condition where the user found that the socket
				// was disconnected, then we told the user to `disconnect_socket()`, then they
				// called this method. Either way we're disconnected, return.
			},
			Some(peer) => {
				match peer.their_node_id {
					Some(node_id) => {
						log_trace!(self.logger,
							"Handling disconnection of peer {}, with {}future connection to the peer possible.",
							log_pubkey!(node_id), if no_connection_possible { "no " } else { "" });
						peers.node_id_to_descriptor.remove(&node_id);
						self.message_handler.chan_handler.peer_disconnected(&node_id, no_connection_possible);
					},
					None => {}
				}
			}
		};
	}

	/// Disconnect a peer given its node id.
	///
	/// Set `no_connection_possible` to true to prevent any further connection with this peer,
	/// force-closing any channels we have with it.
	///
	/// If a peer is connected, this will call [`disconnect_socket`] on the descriptor for the
	/// peer. Thus, be very careful about reentrancy issues.
	///
	/// [`disconnect_socket`]: SocketDescriptor::disconnect_socket
	pub fn disconnect_by_node_id(&self, node_id: PublicKey, no_connection_possible: bool) {
		let mut peers_lock = self.peers.lock().unwrap();
		if let Some(mut descriptor) = peers_lock.node_id_to_descriptor.remove(&node_id) {
			log_trace!(self.logger, "Disconnecting peer with id {} due to client request", node_id);
			peers_lock.peers.remove(&descriptor);
			self.message_handler.chan_handler.peer_disconnected(&node_id, no_connection_possible);
			descriptor.disconnect_socket();
		}
	}

	/// Disconnects all currently-connected peers. This is useful on platforms where there may be
	/// an indication that TCP sockets have stalled even if we weren't around to time them out
	/// using regular ping/pongs.
	pub fn disconnect_all_peers(&self) {
		let mut peers_lock = self.peers.lock().unwrap();
		let peers = &mut *peers_lock;
		for (mut descriptor, peer) in peers.peers.drain() {
			if let Some(node_id) = peer.their_node_id {
				log_trace!(self.logger, "Disconnecting peer with id {} due to client request to disconnect all peers", node_id);
				peers.node_id_to_descriptor.remove(&node_id);
				self.message_handler.chan_handler.peer_disconnected(&node_id, false);
			}
			descriptor.disconnect_socket();
		}
		debug_assert!(peers.node_id_to_descriptor.is_empty());
	}

	/// This is called when we're blocked on sending additional gossip messages until we receive a
	/// pong. If we aren't waiting on a pong, we take this opportunity to send a ping (setting
	/// `awaiting_pong_timer_tick_intervals` to a special flag value to indicate this).
	fn maybe_send_extra_ping(&self, peer: &mut Peer) {
		if peer.awaiting_pong_timer_tick_intervals == 0 {
			peer.awaiting_pong_timer_tick_intervals = -1;
			let ping = msgs::Ping {
				ponglen: 0,
				byteslen: 64,
			};
			self.enqueue_message(peer, &ping);
		}
	}

	/// Send pings to each peer and disconnect those which did not respond to the last round of
	/// pings.
	///
	/// This may be called on any timescale you want, however, roughly once every five to ten
	/// seconds is preferred. The call rate determines both how often we send a ping to our peers
	/// and how much time they have to respond before we disconnect them.
	///
	/// May call [`send_data`] on all [`SocketDescriptor`]s. Thus, be very careful with reentrancy
	/// issues!
	///
	/// [`send_data`]: SocketDescriptor::send_data
	pub fn timer_tick_occurred(&self) {
		let mut peers_lock = self.peers.lock().unwrap();
		{
			let peers = &mut *peers_lock;
			let node_id_to_descriptor = &mut peers.node_id_to_descriptor;
			let peers = &mut peers.peers;
			let mut descriptors_needing_disconnect = Vec::new();
			let peer_count = peers.len();

			peers.retain(|descriptor, peer| {
				let mut do_disconnect_peer = false;
				if !peer.channel_encryptor.is_ready_for_encryption() || peer.their_node_id.is_none() {
					// The peer needs to complete its handshake before we can exchange messages. We
					// give peers one timer tick to complete handshake, reusing
					// `awaiting_pong_timer_tick_intervals` to track number of timer ticks taken
					// for handshake completion.
					if peer.awaiting_pong_timer_tick_intervals != 0 {
						do_disconnect_peer = true;
					} else {
						peer.awaiting_pong_timer_tick_intervals = 1;
						return true;
					}
				}

				if peer.awaiting_pong_timer_tick_intervals == -1 {
					// Magic value set in `maybe_send_extra_ping`.
					peer.awaiting_pong_timer_tick_intervals = 1;
					peer.received_message_since_timer_tick = false;
					return true;
				}

				if do_disconnect_peer
					|| (peer.awaiting_pong_timer_tick_intervals > 0 && !peer.received_message_since_timer_tick)
					|| peer.awaiting_pong_timer_tick_intervals as u64 >
						MAX_BUFFER_DRAIN_TICK_INTERVALS_PER_PEER as u64 * peer_count as u64
				{
					descriptors_needing_disconnect.push(descriptor.clone());
					match peer.their_node_id {
						Some(node_id) => {
							log_trace!(self.logger, "Disconnecting peer with id {} due to ping timeout", node_id);
							node_id_to_descriptor.remove(&node_id);
							self.message_handler.chan_handler.peer_disconnected(&node_id, false);
						}
						None => {},
					}
					return false;
				}
				peer.received_message_since_timer_tick = false;

				if peer.awaiting_pong_timer_tick_intervals > 0 {
					peer.awaiting_pong_timer_tick_intervals += 1;
					return true;
				}

				peer.awaiting_pong_timer_tick_intervals = 1;
				let ping = msgs::Ping {
					ponglen: 0,
					byteslen: 64,
				};
				self.enqueue_message(peer, &ping);
				self.do_attempt_write_data(&mut (descriptor.clone()), &mut *peer);

				true
			});

			for mut descriptor in descriptors_needing_disconnect.drain(..) {
				descriptor.disconnect_socket();
			}
		}
	}
}

fn is_gossip_msg(type_id: u16) -> bool {
	match type_id {
		msgs::ChannelAnnouncement::TYPE |
		msgs::ChannelUpdate::TYPE |
		msgs::NodeAnnouncement::TYPE => true,
		_ => false
	}
}

#[cfg(test)]
mod tests {
	use ln::peer_handler::{PeerManager, MessageHandler, SocketDescriptor, IgnoringMessageHandler};
	use ln::msgs;
	use util::events;
	use util::test_utils;

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

	use prelude::*;
	use sync::{Arc, Mutex};
	use core::sync::atomic::Ordering;

	#[derive(Clone)]
	struct FileDescriptor {
		fd: u16,
		outbound_data: Arc<Mutex<Vec<u8>>>,
	}
	impl PartialEq for FileDescriptor {
		fn eq(&self, other: &Self) -> bool {
			self.fd == other.fd
		}
	}
	impl Eq for FileDescriptor { }
	impl core::hash::Hash for FileDescriptor {
		fn hash<H: core::hash::Hasher>(&self, hasher: &mut H) {
			self.fd.hash(hasher)
		}
	}

	impl SocketDescriptor for FileDescriptor {
		fn send_data(&mut self, data: &[u8], _resume_read: bool) -> usize {
			self.outbound_data.lock().unwrap().extend_from_slice(data);
			data.len()
		}

		fn disconnect_socket(&mut self) {}
	}

	struct PeerManagerCfg {
		chan_handler: test_utils::TestChannelMessageHandler,
		routing_handler: test_utils::TestRoutingMessageHandler,
		logger: test_utils::TestLogger,
	}

	fn create_peermgr_cfgs(peer_count: usize) -> Vec<PeerManagerCfg> {
		let mut cfgs = Vec::new();
		for _ in 0..peer_count {
			cfgs.push(
				PeerManagerCfg{
					chan_handler: test_utils::TestChannelMessageHandler::new(),
					logger: test_utils::TestLogger::new(),
					routing_handler: test_utils::TestRoutingMessageHandler::new(),
				}
			);
		}

		cfgs
	}

	fn create_network<'a>(peer_count: usize, cfgs: &'a Vec<PeerManagerCfg>) -> Vec<PeerManager<FileDescriptor, &'a test_utils::TestChannelMessageHandler, &'a test_utils::TestRoutingMessageHandler, &'a test_utils::TestLogger, IgnoringMessageHandler>> {
		let mut peers = Vec::new();
		for i in 0..peer_count {
			let node_secret = SecretKey::from_slice(&[42 + i as u8; 32]).unwrap();
			let ephemeral_bytes = [i as u8; 32];
			let msg_handler = MessageHandler { chan_handler: &cfgs[i].chan_handler, route_handler: &cfgs[i].routing_handler };
			let peer = PeerManager::new(msg_handler, node_secret, &ephemeral_bytes, &cfgs[i].logger, IgnoringMessageHandler {});
			peers.push(peer);
		}

		peers
	}

	fn establish_connection<'a>(peer_a: &PeerManager<FileDescriptor, &'a test_utils::TestChannelMessageHandler, &'a test_utils::TestRoutingMessageHandler, &'a test_utils::TestLogger, IgnoringMessageHandler>, peer_b: &PeerManager<FileDescriptor, &'a test_utils::TestChannelMessageHandler, &'a test_utils::TestRoutingMessageHandler, &'a test_utils::TestLogger, IgnoringMessageHandler>) -> (FileDescriptor, FileDescriptor) {
		let secp_ctx = Secp256k1::new();
		let a_id = PublicKey::from_secret_key(&secp_ctx, &peer_a.our_node_secret);
		let mut fd_a = FileDescriptor { fd: 1, outbound_data: Arc::new(Mutex::new(Vec::new())) };
		let mut fd_b = FileDescriptor { fd: 1, outbound_data: Arc::new(Mutex::new(Vec::new())) };
		let initial_data = peer_b.new_outbound_connection(a_id, fd_b.clone()).unwrap();
		peer_a.new_inbound_connection(fd_a.clone()).unwrap();
		assert_eq!(peer_a.read_event(&mut fd_a, &initial_data).unwrap(), false);
		peer_a.process_events();
		assert_eq!(peer_b.read_event(&mut fd_b, &fd_a.outbound_data.lock().unwrap().split_off(0)).unwrap(), false);
		peer_b.process_events();
		assert_eq!(peer_a.read_event(&mut fd_a, &fd_b.outbound_data.lock().unwrap().split_off(0)).unwrap(), false);
		(fd_a.clone(), fd_b.clone())
	}

	#[test]
	fn test_disconnect_peer() {
		// Simple test which builds a network of PeerManager, connects and brings them to NoiseState::Finished and
		// push a DisconnectPeer event to remove the node flagged by id
		let cfgs = create_peermgr_cfgs(2);
		let chan_handler = test_utils::TestChannelMessageHandler::new();
		let mut peers = create_network(2, &cfgs);
		establish_connection(&peers[0], &peers[1]);
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 1);

		let secp_ctx = Secp256k1::new();
		let their_id = PublicKey::from_secret_key(&secp_ctx, &peers[1].our_node_secret);

		chan_handler.pending_events.lock().unwrap().push(events::MessageSendEvent::HandleError {
			node_id: their_id,
			action: msgs::ErrorAction::DisconnectPeer { msg: None },
		});
		assert_eq!(chan_handler.pending_events.lock().unwrap().len(), 1);
		peers[0].message_handler.chan_handler = &chan_handler;

		peers[0].process_events();
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 0);
	}

	#[test]
	fn test_timer_tick_occurred() {
		// Create peers, a vector of two peer managers, perform initial set up and check that peers[0] has one Peer.
		let cfgs = create_peermgr_cfgs(2);
		let peers = create_network(2, &cfgs);
		establish_connection(&peers[0], &peers[1]);
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 1);

		// peers[0] awaiting_pong is set to true, but the Peer is still connected
		peers[0].timer_tick_occurred();
		peers[0].process_events();
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 1);

		// Since timer_tick_occurred() is called again when awaiting_pong is true, all Peers are disconnected
		peers[0].timer_tick_occurred();
		peers[0].process_events();
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 0);
	}

	#[test]
	fn test_do_attempt_write_data() {
		// Create 2 peers with custom TestRoutingMessageHandlers and connect them.
		let cfgs = create_peermgr_cfgs(2);
		cfgs[0].routing_handler.request_full_sync.store(true, Ordering::Release);
		cfgs[1].routing_handler.request_full_sync.store(true, Ordering::Release);
		let peers = create_network(2, &cfgs);

		// By calling establish_connect, we trigger do_attempt_write_data between
		// the peers. Previously this function would mistakenly enter an infinite loop
		// when there were more channel messages available than could fit into a peer's
		// buffer. This issue would now be detected by this test (because we use custom
		// RoutingMessageHandlers that intentionally return more channel messages
		// than can fit into a peer's buffer).
		let (mut fd_a, mut fd_b) = establish_connection(&peers[0], &peers[1]);

		// Make each peer to read the messages that the other peer just wrote to them. Note that
		// due to the max-messagse-before-ping limits this may take a few iterations to complete.
		for _ in 0..150/super::BUFFER_DRAIN_MSGS_PER_TICK + 1 {
			peers[0].process_events();
			let b_read_data = fd_a.outbound_data.lock().unwrap().split_off(0);
			assert!(!b_read_data.is_empty());

			peers[1].read_event(&mut fd_b, &b_read_data).unwrap();
			peers[1].process_events();

			let a_read_data = fd_b.outbound_data.lock().unwrap().split_off(0);
			assert!(!a_read_data.is_empty());
			peers[0].read_event(&mut fd_a, &a_read_data).unwrap();

			peers[1].process_events();
			assert_eq!(fd_b.outbound_data.lock().unwrap().len(), 0, "Until B receives data, it shouldn't send more messages");
		}

		// Check that each peer has received the expected number of channel updates and channel
		// announcements.
		assert_eq!(cfgs[0].routing_handler.chan_upds_recvd.load(Ordering::Acquire), 100);
		assert_eq!(cfgs[0].routing_handler.chan_anns_recvd.load(Ordering::Acquire), 50);
		assert_eq!(cfgs[1].routing_handler.chan_upds_recvd.load(Ordering::Acquire), 100);
		assert_eq!(cfgs[1].routing_handler.chan_anns_recvd.load(Ordering::Acquire), 50);
	}

	#[test]
	fn test_handshake_timeout() {
		// Tests that we time out a peer still waiting on handshake completion after a full timer
		// tick.
		let cfgs = create_peermgr_cfgs(2);
		cfgs[0].routing_handler.request_full_sync.store(true, Ordering::Release);
		cfgs[1].routing_handler.request_full_sync.store(true, Ordering::Release);
		let peers = create_network(2, &cfgs);

		let secp_ctx = Secp256k1::new();
		let a_id = PublicKey::from_secret_key(&secp_ctx, &peers[0].our_node_secret);
		let mut fd_a = FileDescriptor { fd: 1, outbound_data: Arc::new(Mutex::new(Vec::new())) };
		let mut fd_b = FileDescriptor { fd: 1, outbound_data: Arc::new(Mutex::new(Vec::new())) };
		let initial_data = peers[1].new_outbound_connection(a_id, fd_b.clone()).unwrap();
		peers[0].new_inbound_connection(fd_a.clone()).unwrap();

		// If we get a single timer tick before completion, that's fine
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 1);
		peers[0].timer_tick_occurred();
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 1);

		assert_eq!(peers[0].read_event(&mut fd_a, &initial_data).unwrap(), false);
		peers[0].process_events();
		assert_eq!(peers[1].read_event(&mut fd_b, &fd_a.outbound_data.lock().unwrap().split_off(0)).unwrap(), false);
		peers[1].process_events();

		// ...but if we get a second timer tick, we should disconnect the peer
		peers[0].timer_tick_occurred();
		assert_eq!(peers[0].peers.lock().unwrap().peers.len(), 0);

		assert!(peers[0].read_event(&mut fd_a, &fd_b.outbound_data.lock().unwrap().split_off(0)).is_err());
	}
}