Direct connect for OnionMessage sending

fuzz/src/onion_message.rs

@@ -79,6 +79,7 @@ impl MessageRouter for TestMessageRouter {
 		Ok(OnionMessagePath {
 			intermediate_nodes: vec![],
 			destination,
+			addresses: None,
 		})
 	}
 }
@@ -269,7 +270,9 @@ mod tests {
 						"Received an onion message with path_id None and a reply_path: Custom(TestCustomMessage)"
 						.to_string())), Some(&1));
 			assert_eq!(log_entries.get(&("lightning::onion_message::messenger".to_string(),
-						"Sending onion message: TestCustomMessage".to_string())), Some(&1));
+						"Constructing onion message when responding to Custom onion message with path_id None: TestCustomMessage".to_string())), Some(&1));
+			assert_eq!(log_entries.get(&("lightning::onion_message::messenger".to_string(),
+						"Buffered onion message when responding to Custom onion message with path_id None".to_string())), Some(&1));
 		}
 
 		let two_unblinded_hops_om = "\

lightning-background-processor/src/lib.rs

@@ -30,6 +30,7 @@ use lightning::events::{Event, PathFailure};
 #[cfg(feature = "std")]
 use lightning::events::{EventHandler, EventsProvider};
 use lightning::ln::channelmanager::ChannelManager;
+use lightning::ln::msgs::OnionMessageHandler;
 use lightning::ln::peer_handler::APeerManager;
 use lightning::routing::gossip::{NetworkGraph, P2PGossipSync};
 use lightning::routing::utxo::UtxoLookup;
@@ -104,6 +105,11 @@ const PING_TIMER: u64 = 30;
 #[cfg(test)]
 const PING_TIMER: u64 = 1;
 
+#[cfg(not(test))]
+const ONION_MESSAGE_HANDLER_TIMER: u64 = 10;
+#[cfg(test)]
+const ONION_MESSAGE_HANDLER_TIMER: u64 = 1;
+
 /// Prune the network graph of stale entries hourly.
 const NETWORK_PRUNE_TIMER: u64 = 60 * 60;
 
@@ -270,18 +276,20 @@ fn update_scorer<'a, S: 'static + Deref<Target = SC> + Send + Sync, SC: 'a + Wri
 }
 
 macro_rules! define_run_body {
-	($persister: ident, $chain_monitor: ident, $process_chain_monitor_events: expr,
-	 $channel_manager: ident, $process_channel_manager_events: expr,
-	 $gossip_sync: ident, $peer_manager: ident, $logger: ident, $scorer: ident,
-	 $loop_exit_check: expr, $await: expr, $get_timer: expr, $timer_elapsed: expr,
-	 $check_slow_await: expr)
-	=> { {
+	(
+		$persister: ident, $chain_monitor: ident, $process_chain_monitor_events: expr,
+		$channel_manager: ident, $process_channel_manager_events: expr,
+		$peer_manager: ident, $process_onion_message_handler_events: expr, $gossip_sync: ident,
+		$logger: ident, $scorer: ident, $loop_exit_check: expr, $await: expr, $get_timer: expr,
+		$timer_elapsed: expr, $check_slow_await: expr
+	) => { {
 		log_trace!($logger, "Calling ChannelManager's timer_tick_occurred on startup");
 		$channel_manager.timer_tick_occurred();
 		log_trace!($logger, "Rebroadcasting monitor's pending claims on startup");
 		$chain_monitor.rebroadcast_pending_claims();
 
 		let mut last_freshness_call = $get_timer(FRESHNESS_TIMER);
+		let mut last_onion_message_handler_call = $get_timer(ONION_MESSAGE_HANDLER_TIMER);
 		let mut last_ping_call = $get_timer(PING_TIMER);
 		let mut last_prune_call = $get_timer(FIRST_NETWORK_PRUNE_TIMER);
 		let mut last_scorer_persist_call = $get_timer(SCORER_PERSIST_TIMER);
@@ -291,6 +299,7 @@ macro_rules! define_run_body {
 		loop {
 			$process_channel_manager_events;
 			$process_chain_monitor_events;
+			$process_onion_message_handler_events;
 
 			// Note that the PeerManager::process_events may block on ChannelManager's locks,
 			// hence it comes last here. When the ChannelManager finishes whatever it's doing,
@@ -334,6 +343,11 @@ macro_rules! define_run_body {
 				$channel_manager.timer_tick_occurred();
 				last_freshness_call = $get_timer(FRESHNESS_TIMER);
 			}
+			if $timer_elapsed(&mut last_onion_message_handler_call, ONION_MESSAGE_HANDLER_TIMER) {
+				log_trace!($logger, "Calling OnionMessageHandler's timer_tick_occurred");
+				$peer_manager.onion_message_handler().timer_tick_occurred();
+				last_onion_message_handler_call = $get_timer(ONION_MESSAGE_HANDLER_TIMER);
+			}
 			if await_slow {
 				// On various platforms, we may be starved of CPU cycles for several reasons.
 				// E.g. on iOS, if we've been in the background, we will be entirely paused.
@@ -603,8 +617,7 @@ pub async fn process_events_async<
 	CM: 'static + Deref<Target = ChannelManager<CW, T, ES, NS, SP, F, R, L>> + Send + Sync,
 	PGS: 'static + Deref<Target = P2PGossipSync<G, UL, L>> + Send + Sync,
 	RGS: 'static + Deref<Target = RapidGossipSync<G, L>> + Send,
-	APM: APeerManager + Send + Sync,
-	PM: 'static + Deref<Target = APM> + Send + Sync,
+	PM: 'static + Deref + Send + Sync,
 	S: 'static + Deref<Target = SC> + Send + Sync,
 	SC: for<'b> WriteableScore<'b>,
 	SleepFuture: core::future::Future<Output = bool> + core::marker::Unpin,
@@ -627,6 +640,7 @@ where
 	L::Target: 'static + Logger,
 	P::Target: 'static + Persist<<SP::Target as SignerProvider>::EcdsaSigner>,
 	PS::Target: 'static + Persister<'a, CW, T, ES, NS, SP, F, R, L, SC>,
+	PM::Target: APeerManager + Send + Sync,
 {
 	let mut should_break = false;
 	let async_event_handler = |event| {
@@ -650,10 +664,12 @@ where
 			event_handler(event).await;
 		}
 	};
-	define_run_body!(persister,
-		chain_monitor, chain_monitor.process_pending_events_async(async_event_handler).await,
+	define_run_body!(
+		persister, chain_monitor,
+		chain_monitor.process_pending_events_async(async_event_handler).await,
 		channel_manager, channel_manager.process_pending_events_async(async_event_handler).await,
-		gossip_sync, peer_manager, logger, scorer, should_break, {
+		peer_manager, process_onion_message_handler_events_async(&peer_manager, async_event_handler).await,
+		gossip_sync, logger, scorer, should_break, {
 			let fut = Selector {
 				a: channel_manager.get_event_or_persistence_needed_future(),
 				b: chain_monitor.get_update_future(),
@@ -673,7 +689,29 @@ where
 				task::Poll::Ready(exit) => { should_break = exit; true },
 				task::Poll::Pending => false,
 			}
-		}, mobile_interruptable_platform)
+		}, mobile_interruptable_platform
+	)
+}
+
+#[cfg(feature = "futures")]
+async fn process_onion_message_handler_events_async<
+	EventHandlerFuture: core::future::Future<Output = ()>,
+	EventHandler: Fn(Event) -> EventHandlerFuture,
+	PM: 'static + Deref + Send + Sync,
+>(
+	peer_manager: &PM, handler: EventHandler
+)
+where
+	PM::Target: APeerManager + Send + Sync,
+{
+	use lightning::events::EventsProvider;
+
+	let events = core::cell::RefCell::new(Vec::new());
+	peer_manager.onion_message_handler().process_pending_events(&|e| events.borrow_mut().push(e));
+
+	for event in events.into_inner() {
+		handler(event).await
+	}
 }
 
 #[cfg(feature = "std")]
@@ -742,8 +780,7 @@ impl BackgroundProcessor {
 		CM: 'static + Deref<Target = ChannelManager<CW, T, ES, NS, SP, F, R, L>> + Send + Sync,
 		PGS: 'static + Deref<Target = P2PGossipSync<G, UL, L>> + Send + Sync,
 		RGS: 'static + Deref<Target = RapidGossipSync<G, L>> + Send,
-		APM: APeerManager + Send + Sync,
-		PM: 'static + Deref<Target = APM> + Send + Sync,
+		PM: 'static + Deref + Send + Sync,
 		S: 'static + Deref<Target = SC> + Send + Sync,
 		SC: for <'b> WriteableScore<'b>,
 	>(
@@ -763,6 +800,7 @@ impl BackgroundProcessor {
 		L::Target: 'static + Logger,
 		P::Target: 'static + Persist<<SP::Target as SignerProvider>::EcdsaSigner>,
 		PS::Target: 'static + Persister<'a, CW, T, ES, NS, SP, F, R, L, SC>,
+		PM::Target: APeerManager + Send + Sync,
 	{
 		let stop_thread = Arc::new(AtomicBool::new(false));
 		let stop_thread_clone = stop_thread.clone();
@@ -782,14 +820,18 @@ impl BackgroundProcessor {
 				}
 				event_handler.handle_event(event);
 			};
-			define_run_body!(persister, chain_monitor, chain_monitor.process_pending_events(&event_handler),
+			define_run_body!(
+				persister, chain_monitor, chain_monitor.process_pending_events(&event_handler),
 				channel_manager, channel_manager.process_pending_events(&event_handler),
-				gossip_sync, peer_manager, logger, scorer, stop_thread.load(Ordering::Acquire),
+				peer_manager,
+				peer_manager.onion_message_handler().process_pending_events(&event_handler),
+				gossip_sync, logger, scorer, stop_thread.load(Ordering::Acquire),
 				{ Sleeper::from_two_futures(
 					channel_manager.get_event_or_persistence_needed_future(),
 					chain_monitor.get_update_future()
 				).wait_timeout(Duration::from_millis(100)); },
-				|_| Instant::now(), |time: &Instant, dur| time.elapsed().as_secs() > dur, false)
+				|_| Instant::now(), |time: &Instant, dur| time.elapsed().as_secs() > dur, false
+			)
 		});
 		Self { stop_thread: stop_thread_clone, thread_handle: Some(handle) }
 	}
@@ -1362,9 +1404,11 @@ mod tests {
 
 	#[test]
 	fn test_timer_tick_called() {
-		// Test that `ChannelManager::timer_tick_occurred` is called every `FRESHNESS_TIMER`,
-		// `ChainMonitor::rebroadcast_pending_claims` is called every `REBROADCAST_TIMER`, and
-		// `PeerManager::timer_tick_occurred` every `PING_TIMER`.
+		// Test that:
+		// - `ChannelManager::timer_tick_occurred` is called every `FRESHNESS_TIMER`,
+		// - `ChainMonitor::rebroadcast_pending_claims` is called every `REBROADCAST_TIMER`,
+		// - `PeerManager::timer_tick_occurred` is called every `PING_TIMER`, and
+		// - `OnionMessageHandler::timer_tick_occurred` is called every `ONION_MESSAGE_HANDLER_TIMER`.
 		let (_, nodes) = create_nodes(1, "test_timer_tick_called");
 		let data_dir = nodes[0].kv_store.get_data_dir();
 		let persister = Arc::new(Persister::new(data_dir));
@@ -1375,9 +1419,11 @@ mod tests {
 			let desired_log_1 = "Calling ChannelManager's timer_tick_occurred".to_string();
 			let desired_log_2 = "Calling PeerManager's timer_tick_occurred".to_string();
 			let desired_log_3 = "Rebroadcasting monitor's pending claims".to_string();
+			let desired_log_4 = "Calling OnionMessageHandler's timer_tick_occurred".to_string();
 			if log_entries.get(&("lightning_background_processor", desired_log_1)).is_some() &&
 				log_entries.get(&("lightning_background_processor", desired_log_2)).is_some() &&
-				log_entries.get(&("lightning_background_processor", desired_log_3)).is_some() {
+				log_entries.get(&("lightning_background_processor", desired_log_3)).is_some() &&
+				log_entries.get(&("lightning_background_processor", desired_log_4)).is_some() {
 				break
 			}
 		}

lightning/src/events/mod.rs

@@ -530,6 +530,25 @@ pub enum Event {
 		/// serialized prior to LDK version 0.0.117.
 		sender_intended_total_msat: Option<u64>,
 	},
+	/// Indicates that a peer connection with a node is needed in order to send an [`OnionMessage`].
+	///
+	/// Typically, this happens when a [`MessageRouter`] is unable to find a complete path to a
+	/// [`Destination`]. Once a connection is established, any messages buffered by an
+	/// [`OnionMessageHandler`] may be sent.
+	///
+	/// This event will not be generated for onion message forwards; only for sends including
+	/// replies. Handlers should connect to the node otherwise any buffered messages may be lost.
+	///
+	/// [`OnionMessage`]: msgs::OnionMessage
+	/// [`MessageRouter`]: crate::onion_message::MessageRouter
+	/// [`Destination`]: crate::onion_message::Destination
+	/// [`OnionMessageHandler`]: crate::ln::msgs::OnionMessageHandler
+	ConnectionNeeded {
+		/// The node id for the node needing a connection.
+		node_id: PublicKey,
+		/// Sockets for connecting to the node.
+		addresses: Vec<msgs::SocketAddress>,
+	},
 	/// Indicates a request for an invoice failed to yield a response in a reasonable amount of time
 	/// or was explicitly abandoned by [`ChannelManager::abandon_payment`]. This may be for an
 	/// [`InvoiceRequest`] sent for an [`Offer`] or for a [`Refund`] that hasn't been redeemed.
@@ -1190,6 +1209,10 @@ impl Writeable for Event {
 					(0, payment_id, required),
 				})
 			},
+			&Event::ConnectionNeeded { .. } => {
+				35u8.write(writer)?;
+				// Never write ConnectionNeeded events as buffered onion messages aren't serialized.
+			},
 			// Note that, going forward, all new events must only write data inside of
 			// `write_tlv_fields`. Versions 0.0.101+ will ignore odd-numbered events that write
 			// data via `write_tlv_fields`.
@@ -1200,8 +1223,7 @@ impl Writeable for Event {
 impl MaybeReadable for Event {
 	fn read<R: io::Read>(reader: &mut R) -> Result<Option<Self>, msgs::DecodeError> {
 		match Readable::read(reader)? {
-			// Note that we do not write a length-prefixed TLV for FundingGenerationReady events,
-			// unlike all other events, thus we return immediately here.
+			// Note that we do not write a length-prefixed TLV for FundingGenerationReady events.
 			0u8 => Ok(None),
 			1u8 => {
 				let f = || {
@@ -1588,6 +1610,8 @@ impl MaybeReadable for Event {
 				};
 				f()
 			},
+			// Note that we do not write a length-prefixed TLV for ConnectionNeeded events.
+			35u8 => Ok(None),
 			// Versions prior to 0.0.100 did not ignore odd types, instead returning InvalidValue.
 			// Version 0.0.100 failed to properly ignore odd types, possibly resulting in corrupt
 			// reads.

lightning/src/ln/msgs.rs

@@ -52,7 +52,7 @@ use core::fmt::Display;
 use crate::io::{self, Cursor, Read};
 use crate::io_extras::read_to_end;
 
-use crate::events::MessageSendEventsProvider;
+use crate::events::{EventsProvider, MessageSendEventsProvider};
 use crate::util::chacha20poly1305rfc::ChaChaPolyReadAdapter;
 use crate::util::logger;
 use crate::util::ser::{LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer, WithoutLength, FixedLengthReader, HighZeroBytesDroppedBigSize, Hostname, TransactionU16LenLimited, BigSize};
@@ -1631,7 +1631,7 @@ pub trait RoutingMessageHandler : MessageSendEventsProvider {
 }
 
 /// A handler for received [`OnionMessage`]s and for providing generated ones to send.
-pub trait OnionMessageHandler {
+pub trait OnionMessageHandler: EventsProvider {
 	/// Handle an incoming `onion_message` message from the given peer.
 	fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage);
 
@@ -1650,6 +1650,10 @@ pub trait OnionMessageHandler {
 	/// drop and refuse to forward onion messages to this peer.
 	fn peer_disconnected(&self, their_node_id: &PublicKey);
 
+	/// Performs actions that should happen roughly every ten seconds after startup. Allows handlers
+	/// to drop any buffered onion messages intended for prospective peers.
+	fn timer_tick_occurred(&self);
+
 	// Handler information:
 	/// Gets the node feature flags which this handler itself supports. All available handlers are
 	/// queried similarly and their feature flags are OR'd together to form the [`NodeFeatures`]

lightning/src/ln/peer_handler.rs

@@ -19,7 +19,7 @@ use bitcoin::blockdata::constants::ChainHash;
 use bitcoin::secp256k1::{self, Secp256k1, SecretKey, PublicKey};
 
 use crate::sign::{KeysManager, NodeSigner, Recipient};
-use crate::events::{MessageSendEvent, MessageSendEventsProvider};
+use crate::events::{EventHandler, EventsProvider, MessageSendEvent, MessageSendEventsProvider};
 use crate::ln::ChannelId;
 use crate::ln::features::{InitFeatures, NodeFeatures};
 use crate::ln::msgs;
@@ -89,6 +89,9 @@ pub trait CustomMessageHandler: wire::CustomMessageReader {
 /// 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 EventsProvider for IgnoringMessageHandler {
+	fn process_pending_events<H: Deref>(&self, _handler: H) where H::Target: EventHandler {}
+}
 impl MessageSendEventsProvider for IgnoringMessageHandler {
 	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> { Vec::new() }
 }
@@ -115,6 +118,7 @@ impl OnionMessageHandler for IgnoringMessageHandler {
 	fn next_onion_message_for_peer(&self, _peer_node_id: PublicKey) -> Option<msgs::OnionMessage> { None }
 	fn peer_connected(&self, _their_node_id: &PublicKey, _init: &msgs::Init, _inbound: bool) -> Result<(), ()> { Ok(()) }
 	fn peer_disconnected(&self, _their_node_id: &PublicKey) {}
+	fn timer_tick_occurred(&self) {}
 	fn provided_node_features(&self) -> NodeFeatures { NodeFeatures::empty() }
 	fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 		InitFeatures::empty()
@@ -680,6 +684,8 @@ pub trait APeerManager {
 	type NS: Deref<Target=Self::NST>;
 	/// Gets a reference to the underlying [`PeerManager`].
 	fn as_ref(&self) -> &PeerManager<Self::Descriptor, Self::CM, Self::RM, Self::OM, Self::L, Self::CMH, Self::NS>;
+	/// Returns the peer manager's [`OnionMessageHandler`].
+	fn onion_message_handler(&self) -> &Self::OMT;
 }
 
 impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CMH: Deref, NS: Deref>
@@ -705,6 +711,9 @@ APeerManager for PeerManager<Descriptor, CM, RM, OM, L, CMH, NS> where
 	type NST = <NS as Deref>::Target;
 	type NS = NS;
 	fn as_ref(&self) -> &PeerManager<Descriptor, CM, RM, OM, L, CMH, NS> { self }
+	fn onion_message_handler(&self) -> &Self::OMT {
+		self.message_handler.onion_message_handler.deref()
+	}
 }
 
 /// A PeerManager manages a set of peers, described by their [`SocketDescriptor`] and marshalls