rust-lightning/lightning-net-tokio/src/lib.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.

//! A socket handling library for those running in Tokio environments who wish to use
//! rust-lightning with native [`TcpStream`]s.
//!
//! Designed to be as simple as possible, the high-level usage is almost as simple as "hand over a
//! [`TcpStream`] and a reference to a [`PeerManager`] and the rest is handled".
//!
//! The [`PeerManager`], due to the fire-and-forget nature of this logic, must be a reference,
//! (e.g. an [`Arc`]) and must use the [`SocketDescriptor`] provided here as the [`PeerManager`]'s
//! `SocketDescriptor` implementation.
//!
//! Three methods are exposed to register a new connection for handling in [`tokio::spawn`] calls;
//! see their individual docs for details.
//!
//! [`PeerManager`]: lightning::ln::peer_handler::PeerManager

// Prefix these with `rustdoc::` when we update our MSRV to be >= 1.52 to remove warnings.
#![deny(broken_intra_doc_links)]
#![deny(private_intra_doc_links)]

#![deny(missing_docs)]
#![cfg_attr(docsrs, feature(doc_auto_cfg))]

use bitcoin::secp256k1::PublicKey;

use tokio::net::TcpStream;
use tokio::{io, time};
use tokio::sync::mpsc;
use tokio::io::{AsyncReadExt, AsyncWrite, AsyncWriteExt};

use lightning::ln::peer_handler;
use lightning::ln::peer_handler::SocketDescriptor as LnSocketTrait;
use lightning::ln::peer_handler::APeerManager;
use lightning::ln::msgs::NetAddress;

use std::ops::Deref;
use std::task::{self, Poll};
use std::future::Future;
use std::net::SocketAddr;
use std::net::TcpStream as StdTcpStream;
use std::sync::{Arc, Mutex};
use std::sync::atomic::{AtomicU64, Ordering};
use std::time::Duration;
use std::pin::Pin;
use std::hash::Hash;

static ID_COUNTER: AtomicU64 = AtomicU64::new(0);

// We only need to select over multiple futures in one place, and taking on the full `tokio/macros`
// dependency tree in order to do so (which has broken our MSRV before) is excessive. Instead, we
// define a trivial two- and three- select macro with the specific types we need and just use that.

pub(crate) enum SelectorOutput {
	A(Option<()>), B(Option<()>), C(tokio::io::Result<usize>),
}

pub(crate) struct TwoSelector<
	A: Future<Output=Option<()>> + Unpin, B: Future<Output=Option<()>> + Unpin
> {
	pub a: A,
	pub b: B,
}

impl<
	A: Future<Output=Option<()>> + Unpin, B: Future<Output=Option<()>> + Unpin
> Future for TwoSelector<A, B> {
	type Output = SelectorOutput;
	fn poll(mut self: Pin<&mut Self>, ctx: &mut task::Context<'_>) -> Poll<SelectorOutput> {
		match Pin::new(&mut self.a).poll(ctx) {
			Poll::Ready(res) => { return Poll::Ready(SelectorOutput::A(res)); },
			Poll::Pending => {},
		}
		match Pin::new(&mut self.b).poll(ctx) {
			Poll::Ready(res) => { return Poll::Ready(SelectorOutput::B(res)); },
			Poll::Pending => {},
		}
		Poll::Pending
	}
}

pub(crate) struct ThreeSelector<
	A: Future<Output=Option<()>> + Unpin, B: Future<Output=Option<()>> + Unpin, C: Future<Output=tokio::io::Result<usize>> + Unpin
> {
	pub a: A,
	pub b: B,
	pub c: C,
}

impl<
	A: Future<Output=Option<()>> + Unpin, B: Future<Output=Option<()>> + Unpin, C: Future<Output=tokio::io::Result<usize>> + Unpin
> Future for ThreeSelector<A, B, C> {
	type Output = SelectorOutput;
	fn poll(mut self: Pin<&mut Self>, ctx: &mut task::Context<'_>) -> Poll<SelectorOutput> {
		match Pin::new(&mut self.a).poll(ctx) {
			Poll::Ready(res) => { return Poll::Ready(SelectorOutput::A(res)); },
			Poll::Pending => {},
		}
		match Pin::new(&mut self.b).poll(ctx) {
			Poll::Ready(res) => { return Poll::Ready(SelectorOutput::B(res)); },
			Poll::Pending => {},
		}
		match Pin::new(&mut self.c).poll(ctx) {
			Poll::Ready(res) => { return Poll::Ready(SelectorOutput::C(res)); },
			Poll::Pending => {},
		}
		Poll::Pending
	}
}

/// Connection contains all our internal state for a connection - we hold a reference to the
/// Connection object (in an Arc<Mutex<>>) in each SocketDescriptor we create as well as in the
/// read future (which is returned by schedule_read).
struct Connection {
	writer: Option<io::WriteHalf<TcpStream>>,
	// Because our PeerManager is templated by user-provided types, and we can't (as far as I can
	// tell) have a const RawWakerVTable built out of templated functions, we need some indirection
	// between being woken up with write-ready and calling PeerManager::write_buffer_space_avail.
	// This provides that indirection, with a Sender which gets handed to the PeerManager Arc on
	// the schedule_read stack.
	//
	// An alternative (likely more effecient) approach would involve creating a RawWakerVTable at
	// runtime with functions templated by the Arc<PeerManager> type, calling
	// write_buffer_space_avail directly from tokio's write wake, however doing so would require
	// more unsafe voodo than I really feel like writing.
	write_avail: mpsc::Sender<()>,
	// When we are told by rust-lightning to pause read (because we have writes backing up), we do
	// so by setting read_paused. At that point, the read task will stop reading bytes from the
	// socket. To wake it up (without otherwise changing its state, we can push a value into this
	// Sender.
	read_waker: mpsc::Sender<()>,
	read_paused: bool,
	rl_requested_disconnect: bool,
	id: u64,
}
impl Connection {
	async fn poll_event_process<PM: Deref + 'static + Send + Sync>(
		peer_manager: PM,
		mut event_receiver: mpsc::Receiver<()>,
	) where PM::Target: APeerManager<Descriptor = SocketDescriptor> {
		loop {
			if event_receiver.recv().await.is_none() {
				return;
			}
			peer_manager.as_ref().process_events();
		}
	}

	async fn schedule_read<PM: Deref + 'static + Send + Sync + Clone>(
		peer_manager: PM,
		us: Arc<Mutex<Self>>,
		mut reader: io::ReadHalf<TcpStream>,
		mut read_wake_receiver: mpsc::Receiver<()>,
		mut write_avail_receiver: mpsc::Receiver<()>,
	) where PM::Target: APeerManager<Descriptor = SocketDescriptor> {
		// Create a waker to wake up poll_event_process, above
		let (event_waker, event_receiver) = mpsc::channel(1);
		tokio::spawn(Self::poll_event_process(peer_manager.clone(), event_receiver));

		// 4KiB is nice and big without handling too many messages all at once, giving other peers
		// a chance to do some work.
		let mut buf = [0; 4096];

		let mut our_descriptor = SocketDescriptor::new(us.clone());
		// An enum describing why we did/are disconnecting:
		enum Disconnect {
			// Rust-Lightning told us to disconnect, either by returning an Err or by calling
			// SocketDescriptor::disconnect_socket.
			// In this case, we do not call peer_manager.socket_disconnected() as Rust-Lightning
			// already knows we're disconnected.
			CloseConnection,
			// The connection was disconnected for some other reason, ie because the socket was
			// closed.
			// In this case, we do need to call peer_manager.socket_disconnected() to inform
			// Rust-Lightning that the socket is gone.
			PeerDisconnected
		}
		let disconnect_type = loop {
			let read_paused = {
				let us_lock = us.lock().unwrap();
				if us_lock.rl_requested_disconnect {
					break Disconnect::CloseConnection;
				}
				us_lock.read_paused
			};
			// TODO: Drop the Box'ing of the futures once Rust has pin-on-stack support.
			let select_result = if read_paused {
				TwoSelector {
					a: Box::pin(write_avail_receiver.recv()),
					b: Box::pin(read_wake_receiver.recv()),
				}.await
			} else {
				ThreeSelector {
					a: Box::pin(write_avail_receiver.recv()),
					b: Box::pin(read_wake_receiver.recv()),
					c: Box::pin(reader.read(&mut buf)),
				}.await
			};
			match select_result {
				SelectorOutput::A(v) => {
					assert!(v.is_some()); // We can't have dropped the sending end, its in the us Arc!
					if peer_manager.as_ref().write_buffer_space_avail(&mut our_descriptor).is_err() {
						break Disconnect::CloseConnection;
					}
				},
				SelectorOutput::B(_) => {},
				SelectorOutput::C(read) => {
					match read {
						Ok(0) => break Disconnect::PeerDisconnected,
						Ok(len) => {
							let read_res = peer_manager.as_ref().read_event(&mut our_descriptor, &buf[0..len]);
							let mut us_lock = us.lock().unwrap();
							match read_res {
								Ok(pause_read) => {
									if pause_read {
										us_lock.read_paused = true;
									}
								},
								Err(_) => break Disconnect::CloseConnection,
							}
						},
						Err(_) => break Disconnect::PeerDisconnected,
					}
				},
			}
			let _ = event_waker.try_send(());

			// At this point we've processed a message or two, and reset the ping timer for this
			// peer, at least in the "are we still receiving messages" context, if we don't give up
			// our timeslice to another task we may just spin on this peer, starving other peers
			// and eventually disconnecting them for ping timeouts. Instead, we explicitly yield
			// here.
			let _ = tokio::task::yield_now().await;
		};
		let writer_option = us.lock().unwrap().writer.take();
		if let Some(mut writer) = writer_option {
			// If the socket is already closed, shutdown() will fail, so just ignore it.
			let _ = writer.shutdown().await;
		}
		if let Disconnect::PeerDisconnected = disconnect_type {
			peer_manager.as_ref().socket_disconnected(&our_descriptor);
			peer_manager.as_ref().process_events();
		}
	}

	fn new(stream: StdTcpStream) -> (io::ReadHalf<TcpStream>, mpsc::Receiver<()>, mpsc::Receiver<()>, Arc<Mutex<Self>>) {
		// We only ever need a channel of depth 1 here: if we returned a non-full write to the
		// PeerManager, we will eventually get notified that there is room in the socket to write
		// new bytes, which will generate an event. That event will be popped off the queue before
		// we call write_buffer_space_avail, ensuring that we have room to push a new () if, during
		// the write_buffer_space_avail() call, send_data() returns a non-full write.
		let (write_avail, write_receiver) = mpsc::channel(1);
		// Similarly here - our only goal is to make sure the reader wakes up at some point after
		// we shove a value into the channel which comes after we've reset the read_paused bool to
		// false.
		let (read_waker, read_receiver) = mpsc::channel(1);
		stream.set_nonblocking(true).unwrap();
		let (reader, writer) = io::split(TcpStream::from_std(stream).unwrap());

		(reader, write_receiver, read_receiver,
		Arc::new(Mutex::new(Self {
			writer: Some(writer), write_avail, read_waker, read_paused: false,
			rl_requested_disconnect: false,
			id: ID_COUNTER.fetch_add(1, Ordering::AcqRel)
		})))
	}
}

fn get_addr_from_stream(stream: &StdTcpStream) -> Option<NetAddress> {
	match stream.peer_addr() {
		Ok(SocketAddr::V4(sockaddr)) => Some(NetAddress::IPv4 {
			addr: sockaddr.ip().octets(),
			port: sockaddr.port(),
		}),
		Ok(SocketAddr::V6(sockaddr)) => Some(NetAddress::IPv6 {
			addr: sockaddr.ip().octets(),
			port: sockaddr.port(),
		}),
		Err(_) => None,
	}
}

/// Process incoming messages and feed outgoing messages on the provided socket generated by
/// accepting an incoming connection.
///
/// The returned future will complete when the peer is disconnected and associated handling
/// futures are freed, though, because all processing futures are spawned with tokio::spawn, you do
/// not need to poll the provided future in order to make progress.
pub fn setup_inbound<PM: Deref + 'static + Send + Sync + Clone>(
	peer_manager: PM,
	stream: StdTcpStream,
) -> impl std::future::Future<Output=()>
where PM::Target: APeerManager<Descriptor = SocketDescriptor> {
	let remote_addr = get_addr_from_stream(&stream);
	let (reader, write_receiver, read_receiver, us) = Connection::new(stream);
	#[cfg(test)]
	let last_us = Arc::clone(&us);

	let handle_opt = if peer_manager.as_ref().new_inbound_connection(SocketDescriptor::new(us.clone()), remote_addr).is_ok() {
		Some(tokio::spawn(Connection::schedule_read(peer_manager, us, reader, read_receiver, write_receiver)))
	} else {
		// Note that we will skip socket_disconnected here, in accordance with the PeerManager
		// requirements.
		None
	};

	async move {
		if let Some(handle) = handle_opt {
			if let Err(e) = handle.await {
				assert!(e.is_cancelled());
			} else {
				// This is certainly not guaranteed to always be true - the read loop may exit
				// while there are still pending write wakers that need to be woken up after the
				// socket shutdown(). Still, as a check during testing, to make sure tokio doesn't
				// keep too many wakers around, this makes sense. The race should be rare (we do
				// some work after shutdown()) and an error would be a major memory leak.
				#[cfg(test)]
				debug_assert!(Arc::try_unwrap(last_us).is_ok());
			}
		}
	}
}

/// Process incoming messages and feed outgoing messages on the provided socket generated by
/// making an outbound connection which is expected to be accepted by a peer with the given
/// public key. The relevant processing is set to run free (via tokio::spawn).
///
/// The returned future will complete when the peer is disconnected and associated handling
/// futures are freed, though, because all processing futures are spawned with tokio::spawn, you do
/// not need to poll the provided future in order to make progress.
pub fn setup_outbound<PM: Deref + 'static + Send + Sync + Clone>(
	peer_manager: PM,
	their_node_id: PublicKey,
	stream: StdTcpStream,
) -> impl std::future::Future<Output=()>
where PM::Target: APeerManager<Descriptor = SocketDescriptor> {
	let remote_addr = get_addr_from_stream(&stream);
	let (reader, mut write_receiver, read_receiver, us) = Connection::new(stream);
	#[cfg(test)]
	let last_us = Arc::clone(&us);
	let handle_opt = if let Ok(initial_send) = peer_manager.as_ref().new_outbound_connection(their_node_id, SocketDescriptor::new(us.clone()), remote_addr) {
		Some(tokio::spawn(async move {
			// We should essentially always have enough room in a TCP socket buffer to send the
			// initial 10s of bytes. However, tokio running in single-threaded mode will always
			// fail writes and wake us back up later to write. Thus, we handle a single
			// std::task::Poll::Pending but still expect to write the full set of bytes at once
			// and use a relatively tight timeout.
			if let Ok(Ok(())) = tokio::time::timeout(Duration::from_millis(100), async {
				loop {
					match SocketDescriptor::new(us.clone()).send_data(&initial_send, true) {
						v if v == initial_send.len() => break Ok(()),
						0 => {
							write_receiver.recv().await;
							// In theory we could check for if we've been instructed to disconnect
							// the peer here, but its OK to just skip it - we'll check for it in
							// schedule_read prior to any relevant calls into RL.
						},
						_ => {
							eprintln!("Failed to write first full message to socket!");
							peer_manager.as_ref().socket_disconnected(&SocketDescriptor::new(Arc::clone(&us)));
							break Err(());
						}
					}
				}
			}).await {
				Connection::schedule_read(peer_manager, us, reader, read_receiver, write_receiver).await;
			}
		}))
	} else {
		// Note that we will skip socket_disconnected here, in accordance with the PeerManager
		// requirements.
		None
	};

	async move {
		if let Some(handle) = handle_opt {
			if let Err(e) = handle.await {
				assert!(e.is_cancelled());
			} else {
				// This is certainly not guaranteed to always be true - the read loop may exit
				// while there are still pending write wakers that need to be woken up after the
				// socket shutdown(). Still, as a check during testing, to make sure tokio doesn't
				// keep too many wakers around, this makes sense. The race should be rare (we do
				// some work after shutdown()) and an error would be a major memory leak.
				#[cfg(test)]
				debug_assert!(Arc::try_unwrap(last_us).is_ok());
			}
		}
	}
}

/// Process incoming messages and feed outgoing messages on a new connection made to the given
/// socket address which is expected to be accepted by a peer with the given public key (by
/// scheduling futures with tokio::spawn).
///
/// Shorthand for TcpStream::connect(addr) with a timeout followed by setup_outbound().
///
/// Returns a future (as the fn is async) which needs to be polled to complete the connection and
/// connection setup. That future then returns a future which will complete when the peer is
/// disconnected and associated handling futures are freed, though, because all processing in said
/// futures are spawned with tokio::spawn, you do not need to poll the second future in order to
/// make progress.
pub async fn connect_outbound<PM: Deref + 'static + Send + Sync + Clone>(
	peer_manager: PM,
	their_node_id: PublicKey,
	addr: SocketAddr,
) -> Option<impl std::future::Future<Output=()>>
where PM::Target: APeerManager<Descriptor = SocketDescriptor> {
	if let Ok(Ok(stream)) = time::timeout(Duration::from_secs(10), async { TcpStream::connect(&addr).await.map(|s| s.into_std().unwrap()) }).await {
		Some(setup_outbound(peer_manager, their_node_id, stream))
	} else { None }
}

const SOCK_WAKER_VTABLE: task::RawWakerVTable =
	task::RawWakerVTable::new(clone_socket_waker, wake_socket_waker, wake_socket_waker_by_ref, drop_socket_waker);

fn clone_socket_waker(orig_ptr: *const ()) -> task::RawWaker {
	write_avail_to_waker(orig_ptr as *const mpsc::Sender<()>)
}
// When waking, an error should be fine. Most likely we got two send_datas in a row, both of which
// failed to fully write, but we only need to call write_buffer_space_avail() once. Otherwise, the
// sending thread may have already gone away due to a socket close, in which case there's nothing
// to wake up anyway.
fn wake_socket_waker(orig_ptr: *const ()) {
	let sender = unsafe { &mut *(orig_ptr as *mut mpsc::Sender<()>) };
	let _ = sender.try_send(());
	drop_socket_waker(orig_ptr);
}
fn wake_socket_waker_by_ref(orig_ptr: *const ()) {
	let sender_ptr = orig_ptr as *const mpsc::Sender<()>;
	let sender = unsafe { (*sender_ptr).clone() };
	let _ = sender.try_send(());
}
fn drop_socket_waker(orig_ptr: *const ()) {
	let _orig_box = unsafe { Box::from_raw(orig_ptr as *mut mpsc::Sender<()>) };
	// _orig_box is now dropped
}
fn write_avail_to_waker(sender: *const mpsc::Sender<()>) -> task::RawWaker {
	let new_box = Box::leak(Box::new(unsafe { (*sender).clone() }));
	let new_ptr = new_box as *const mpsc::Sender<()>;
	task::RawWaker::new(new_ptr as *const (), &SOCK_WAKER_VTABLE)
}

/// The SocketDescriptor used to refer to sockets by a PeerHandler. This is pub only as it is a
/// type in the template of PeerHandler.
pub struct SocketDescriptor {
	conn: Arc<Mutex<Connection>>,
	id: u64,
}
impl SocketDescriptor {
	fn new(conn: Arc<Mutex<Connection>>) -> Self {
		let id = conn.lock().unwrap().id;
		Self { conn, id }
	}
}
impl peer_handler::SocketDescriptor for SocketDescriptor {
	fn send_data(&mut self, data: &[u8], resume_read: bool) -> usize {
		// To send data, we take a lock on our Connection to access the WriteHalf of the TcpStream,
		// writing to it if there's room in the kernel buffer, or otherwise create a new Waker with
		// a SocketDescriptor in it which can wake up the write_avail Sender, waking up the
		// processing future which will call write_buffer_space_avail and we'll end up back here.
		let mut us = self.conn.lock().unwrap();
		if us.writer.is_none() {
			// The writer gets take()n when it is time to shut down, so just fast-return 0 here.
			return 0;
		}

		if resume_read && us.read_paused {
			// The schedule_read future may go to lock up but end up getting woken up by there
			// being more room in the write buffer, dropping the other end of this Sender
			// before we get here, so we ignore any failures to wake it up.
			us.read_paused = false;
			let _ = us.read_waker.try_send(());
		}
		if data.is_empty() { return 0; }
		let waker = unsafe { task::Waker::from_raw(write_avail_to_waker(&us.write_avail)) };
		let mut ctx = task::Context::from_waker(&waker);
		let mut written_len = 0;
		loop {
			match std::pin::Pin::new(us.writer.as_mut().unwrap()).poll_write(&mut ctx, &data[written_len..]) {
				task::Poll::Ready(Ok(res)) => {
					// The tokio docs *seem* to indicate this can't happen, and I certainly don't
					// know how to handle it if it does (cause it should be a Poll::Pending
					// instead):
					assert_ne!(res, 0);
					written_len += res;
					if written_len == data.len() { return written_len; }
				},
				task::Poll::Ready(Err(e)) => {
					// The tokio docs *seem* to indicate this can't happen, and I certainly don't
					// know how to handle it if it does (cause it should be a Poll::Pending
					// instead):
					assert_ne!(e.kind(), io::ErrorKind::WouldBlock);
					// Probably we've already been closed, just return what we have and let the
					// read thread handle closing logic.
					return written_len;
				},
				task::Poll::Pending => {
					// We're queued up for a write event now, but we need to make sure we also
					// pause read given we're now waiting on the remote end to ACK (and in
					// accordance with the send_data() docs).
					us.read_paused = true;
					// Further, to avoid any current pending read causing a `read_event` call, wake
					// up the read_waker and restart its loop.
					let _ = us.read_waker.try_send(());
					return written_len;
				},
			}
		}
	}

	fn disconnect_socket(&mut self) {
		let mut us = self.conn.lock().unwrap();
		us.rl_requested_disconnect = true;
		// Wake up the sending thread, assuming it is still alive
		let _ = us.write_avail.try_send(());
	}
}
impl Clone for SocketDescriptor {
	fn clone(&self) -> Self {
		Self {
			conn: Arc::clone(&self.conn),
			id: self.id,
		}
	}
}
impl Eq for SocketDescriptor {}
impl PartialEq for SocketDescriptor {
	fn eq(&self, o: &Self) -> bool {
		self.id == o.id
	}
}
impl Hash for SocketDescriptor {
	fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
		self.id.hash(state);
	}
}

#[cfg(test)]
mod tests {
	use lightning::ln::features::*;
	use lightning::ln::msgs::*;
	use lightning::ln::peer_handler::{MessageHandler, PeerManager};
	use lightning::ln::features::NodeFeatures;
	use lightning::routing::gossip::NodeId;
	use lightning::events::*;
	use lightning::util::test_utils::TestNodeSigner;
	use bitcoin::Network;
	use bitcoin::blockdata::constants::ChainHash;
	use bitcoin::secp256k1::{Secp256k1, SecretKey, PublicKey};

	use tokio::sync::mpsc;

	use std::mem;
	use std::sync::atomic::{AtomicBool, Ordering};
	use std::sync::{Arc, Mutex};
	use std::time::Duration;

	pub struct TestLogger();
	impl lightning::util::logger::Logger for TestLogger {
		fn log(&self, record: &lightning::util::logger::Record) {
			println!("{:<5} [{} : {}, {}] {}", record.level.to_string(), record.module_path, record.file, record.line, record.args);
		}
	}

	struct MsgHandler{
		expected_pubkey: PublicKey,
		pubkey_connected: mpsc::Sender<()>,
		pubkey_disconnected: mpsc::Sender<()>,
		disconnected_flag: AtomicBool,
		msg_events: Mutex<Vec<MessageSendEvent>>,
	}
	impl RoutingMessageHandler for MsgHandler {
		fn handle_node_announcement(&self, _msg: &NodeAnnouncement) -> Result<bool, LightningError> { Ok(false) }
		fn handle_channel_announcement(&self, _msg: &ChannelAnnouncement) -> Result<bool, LightningError> { Ok(false) }
		fn handle_channel_update(&self, _msg: &ChannelUpdate) -> Result<bool, LightningError> { Ok(false) }
		fn get_next_channel_announcement(&self, _starting_point: u64) -> Option<(ChannelAnnouncement, Option<ChannelUpdate>, Option<ChannelUpdate>)> { None }
		fn get_next_node_announcement(&self, _starting_point: Option<&NodeId>) -> Option<NodeAnnouncement> { None }
		fn peer_connected(&self, _their_node_id: &PublicKey, _init_msg: &Init, _inbound: bool) -> Result<(), ()> { Ok(()) }
		fn handle_reply_channel_range(&self, _their_node_id: &PublicKey, _msg: ReplyChannelRange) -> Result<(), LightningError> { Ok(()) }
		fn handle_reply_short_channel_ids_end(&self, _their_node_id: &PublicKey, _msg: ReplyShortChannelIdsEnd) -> Result<(), LightningError> { Ok(()) }
		fn handle_query_channel_range(&self, _their_node_id: &PublicKey, _msg: QueryChannelRange) -> Result<(), LightningError> { Ok(()) }
		fn handle_query_short_channel_ids(&self, _their_node_id: &PublicKey, _msg: QueryShortChannelIds) -> Result<(), LightningError> { Ok(()) }
		fn provided_node_features(&self) -> NodeFeatures { NodeFeatures::empty() }
		fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures { InitFeatures::empty() }
		fn processing_queue_high(&self) -> bool { false }
	}
	impl ChannelMessageHandler for MsgHandler {
		fn handle_open_channel(&self, _their_node_id: &PublicKey, _msg: &OpenChannel) {}
		fn handle_accept_channel(&self, _their_node_id: &PublicKey, _msg: &AcceptChannel) {}
		fn handle_funding_created(&self, _their_node_id: &PublicKey, _msg: &FundingCreated) {}
		fn handle_funding_signed(&self, _their_node_id: &PublicKey, _msg: &FundingSigned) {}
		fn handle_channel_ready(&self, _their_node_id: &PublicKey, _msg: &ChannelReady) {}
		fn handle_shutdown(&self, _their_node_id: &PublicKey, _msg: &Shutdown) {}
		fn handle_closing_signed(&self, _their_node_id: &PublicKey, _msg: &ClosingSigned) {}
		fn handle_update_add_htlc(&self, _their_node_id: &PublicKey, _msg: &UpdateAddHTLC) {}
		fn handle_update_fulfill_htlc(&self, _their_node_id: &PublicKey, _msg: &UpdateFulfillHTLC) {}
		fn handle_update_fail_htlc(&self, _their_node_id: &PublicKey, _msg: &UpdateFailHTLC) {}
		fn handle_update_fail_malformed_htlc(&self, _their_node_id: &PublicKey, _msg: &UpdateFailMalformedHTLC) {}
		fn handle_commitment_signed(&self, _their_node_id: &PublicKey, _msg: &CommitmentSigned) {}
		fn handle_revoke_and_ack(&self, _their_node_id: &PublicKey, _msg: &RevokeAndACK) {}
		fn handle_update_fee(&self, _their_node_id: &PublicKey, _msg: &UpdateFee) {}
		fn handle_announcement_signatures(&self, _their_node_id: &PublicKey, _msg: &AnnouncementSignatures) {}
		fn handle_channel_update(&self, _their_node_id: &PublicKey, _msg: &ChannelUpdate) {}
		fn handle_open_channel_v2(&self, _their_node_id: &PublicKey, _msg: &OpenChannelV2) {}
		fn handle_accept_channel_v2(&self, _their_node_id: &PublicKey, _msg: &AcceptChannelV2) {}
		fn handle_tx_add_input(&self, _their_node_id: &PublicKey, _msg: &TxAddInput) {}
		fn handle_tx_add_output(&self, _their_node_id: &PublicKey, _msg: &TxAddOutput) {}
		fn handle_tx_remove_input(&self, _their_node_id: &PublicKey, _msg: &TxRemoveInput) {}
		fn handle_tx_remove_output(&self, _their_node_id: &PublicKey, _msg: &TxRemoveOutput) {}
		fn handle_tx_complete(&self, _their_node_id: &PublicKey, _msg: &TxComplete) {}
		fn handle_tx_signatures(&self, _their_node_id: &PublicKey, _msg: &TxSignatures) {}
		fn handle_tx_init_rbf(&self, _their_node_id: &PublicKey, _msg: &TxInitRbf) {}
		fn handle_tx_ack_rbf(&self, _their_node_id: &PublicKey, _msg: &TxAckRbf) {}
		fn handle_tx_abort(&self, _their_node_id: &PublicKey, _msg: &TxAbort) {}
		fn peer_disconnected(&self, their_node_id: &PublicKey) {
			if *their_node_id == self.expected_pubkey {
				self.disconnected_flag.store(true, Ordering::SeqCst);
				self.pubkey_disconnected.clone().try_send(()).unwrap();
			}
		}
		fn peer_connected(&self, their_node_id: &PublicKey, _init_msg: &Init, _inbound: bool) -> Result<(), ()> {
			if *their_node_id == self.expected_pubkey {
				self.pubkey_connected.clone().try_send(()).unwrap();
			}
			Ok(())
		}
		fn handle_channel_reestablish(&self, _their_node_id: &PublicKey, _msg: &ChannelReestablish) {}
		fn handle_error(&self, _their_node_id: &PublicKey, _msg: &ErrorMessage) {}
		fn provided_node_features(&self) -> NodeFeatures { NodeFeatures::empty() }
		fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures { InitFeatures::empty() }
		fn get_genesis_hashes(&self) -> Option<Vec<ChainHash>> {
			Some(vec![ChainHash::using_genesis_block(Network::Testnet)])
		}
	}
	impl MessageSendEventsProvider for MsgHandler {
		fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
			let mut ret = Vec::new();
			mem::swap(&mut *self.msg_events.lock().unwrap(), &mut ret);
			ret
		}
	}

	fn make_tcp_connection() -> (std::net::TcpStream, std::net::TcpStream) {
		if let Ok(listener) = std::net::TcpListener::bind("127.0.0.1:9735") {
			(std::net::TcpStream::connect("127.0.0.1:9735").unwrap(), listener.accept().unwrap().0)
		} else if let Ok(listener) = std::net::TcpListener::bind("127.0.0.1:19735") {
			(std::net::TcpStream::connect("127.0.0.1:19735").unwrap(), listener.accept().unwrap().0)
		} else if let Ok(listener) = std::net::TcpListener::bind("127.0.0.1:9997") {
			(std::net::TcpStream::connect("127.0.0.1:9997").unwrap(), listener.accept().unwrap().0)
		} else if let Ok(listener) = std::net::TcpListener::bind("127.0.0.1:9998") {
			(std::net::TcpStream::connect("127.0.0.1:9998").unwrap(), listener.accept().unwrap().0)
		} else if let Ok(listener) = std::net::TcpListener::bind("127.0.0.1:9999") {
			(std::net::TcpStream::connect("127.0.0.1:9999").unwrap(), listener.accept().unwrap().0)
		} else if let Ok(listener) = std::net::TcpListener::bind("127.0.0.1:46926") {
			(std::net::TcpStream::connect("127.0.0.1:46926").unwrap(), listener.accept().unwrap().0)
		} else { panic!("Failed to bind to v4 localhost on common ports"); }
	}

	async fn do_basic_connection_test() {
		let secp_ctx = Secp256k1::new();
		let a_key = SecretKey::from_slice(&[1; 32]).unwrap();
		let b_key = SecretKey::from_slice(&[1; 32]).unwrap();
		let a_pub = PublicKey::from_secret_key(&secp_ctx, &a_key);
		let b_pub = PublicKey::from_secret_key(&secp_ctx, &b_key);

		let (a_connected_sender, mut a_connected) = mpsc::channel(1);
		let (a_disconnected_sender, mut a_disconnected) = mpsc::channel(1);
		let a_handler = Arc::new(MsgHandler {
			expected_pubkey: b_pub,
			pubkey_connected: a_connected_sender,
			pubkey_disconnected: a_disconnected_sender,
			disconnected_flag: AtomicBool::new(false),
			msg_events: Mutex::new(Vec::new()),
		});
		let a_manager = Arc::new(PeerManager::new(MessageHandler {
			chan_handler: Arc::clone(&a_handler),
			route_handler: Arc::clone(&a_handler),
			onion_message_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{}),
			custom_message_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{}),
		}, 0, &[1; 32], Arc::new(TestLogger()), Arc::new(TestNodeSigner::new(a_key))));

		let (b_connected_sender, mut b_connected) = mpsc::channel(1);
		let (b_disconnected_sender, mut b_disconnected) = mpsc::channel(1);
		let b_handler = Arc::new(MsgHandler {
			expected_pubkey: a_pub,
			pubkey_connected: b_connected_sender,
			pubkey_disconnected: b_disconnected_sender,
			disconnected_flag: AtomicBool::new(false),
			msg_events: Mutex::new(Vec::new()),
		});
		let b_manager = Arc::new(PeerManager::new(MessageHandler {
			chan_handler: Arc::clone(&b_handler),
			route_handler: Arc::clone(&b_handler),
			onion_message_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{}),
			custom_message_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{}),
		}, 0, &[2; 32], Arc::new(TestLogger()), Arc::new(TestNodeSigner::new(b_key))));

		// We bind on localhost, hoping the environment is properly configured with a local
		// address. This may not always be the case in containers and the like, so if this test is
		// failing for you check that you have a loopback interface and it is configured with
		// 127.0.0.1.
		let (conn_a, conn_b) = make_tcp_connection();

		let fut_a = super::setup_outbound(Arc::clone(&a_manager), b_pub, conn_a);
		let fut_b = super::setup_inbound(b_manager, conn_b);

		tokio::time::timeout(Duration::from_secs(10), a_connected.recv()).await.unwrap();
		tokio::time::timeout(Duration::from_secs(1), b_connected.recv()).await.unwrap();

		a_handler.msg_events.lock().unwrap().push(MessageSendEvent::HandleError {
			node_id: b_pub, action: ErrorAction::DisconnectPeer { msg: None }
		});
		assert!(!a_handler.disconnected_flag.load(Ordering::SeqCst));
		assert!(!b_handler.disconnected_flag.load(Ordering::SeqCst));

		a_manager.process_events();
		tokio::time::timeout(Duration::from_secs(10), a_disconnected.recv()).await.unwrap();
		tokio::time::timeout(Duration::from_secs(1), b_disconnected.recv()).await.unwrap();
		assert!(a_handler.disconnected_flag.load(Ordering::SeqCst));
		assert!(b_handler.disconnected_flag.load(Ordering::SeqCst));

		fut_a.await;
		fut_b.await;
	}

	#[tokio::test(flavor = "multi_thread")]
	async fn basic_threaded_connection_test() {
		do_basic_connection_test().await;
	}

	#[tokio::test]
	async fn basic_unthreaded_connection_test() {
		do_basic_connection_test().await;
	}

	async fn race_disconnect_accept() {
		// Previously, if we handed an already-disconnected socket to `setup_inbound` we'd panic.
		// This attempts to find other similar races by opening connections and shutting them down
		// while connecting. Sadly in testing this did *not* reproduce the previous issue.
		let secp_ctx = Secp256k1::new();
		let a_key = SecretKey::from_slice(&[1; 32]).unwrap();
		let b_key = SecretKey::from_slice(&[2; 32]).unwrap();
		let b_pub = PublicKey::from_secret_key(&secp_ctx, &b_key);

		let a_manager = Arc::new(PeerManager::new(MessageHandler {
			chan_handler: Arc::new(lightning::ln::peer_handler::ErroringMessageHandler::new()),
			onion_message_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{}),
			route_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{}),
			custom_message_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{}),
		}, 0, &[1; 32], Arc::new(TestLogger()), Arc::new(TestNodeSigner::new(a_key))));

		// Make two connections, one for an inbound and one for an outbound connection
		let conn_a = {
			let (conn_a, _) = make_tcp_connection();
			conn_a
		};
		let conn_b = {
			let (_, conn_b) = make_tcp_connection();
			conn_b
		};

		// Call connection setup inside new tokio tasks.
		let manager_reference = Arc::clone(&a_manager);
		tokio::spawn(async move {
			super::setup_inbound(manager_reference, conn_a).await
		});
		tokio::spawn(async move {
			super::setup_outbound(a_manager, b_pub, conn_b).await
		});
	}

	#[tokio::test(flavor = "multi_thread")]
	async fn threaded_race_disconnect_accept() {
		race_disconnect_accept().await;
	}

	#[tokio::test]
	async fn unthreaded_race_disconnect_accept() {
		race_disconnect_accept().await;
	}
}