Use `{}`, not `{:?}` for `PublicKey` logging
[rust-lightning] / lightning / src / onion_message / messenger.rs
index 8d98e284e954b15032232b04e2fe7d4156339b7f..c6b925704967b67773a2ef06c2ad2c21f2517e25 100644 (file)
@@ -7,8 +7,8 @@
 // You may not use this file except in accordance with one or both of these
 // licenses.
 
-//! LDK sends, receives, and forwards onion messages via the [`OnionMessenger`]. See its docs for
-//! more information.
+//! LDK sends, receives, and forwards onion messages via this [`OnionMessenger`], which lives here,
+//! as well as various types, traits, and utilities that it uses.
 
 use bitcoin::hashes::{Hash, HashEngine};
 use bitcoin::hashes::hmac::{Hmac, HmacEngine};
@@ -18,14 +18,13 @@ use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
 use crate::blinded_path::BlindedPath;
 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
 use crate::blinded_path::utils;
-use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
-#[cfg(not(c_bindings))]
-use crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
+use crate::events::{Event, EventHandler, EventsProvider};
+use crate::sign::{EntropySource, NodeSigner, Recipient};
 use crate::ln::features::{InitFeatures, NodeFeatures};
-use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler};
+use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
 use crate::ln::onion_utils;
-use crate::ln::peer_handler::IgnoringMessageHandler;
-pub use super::packet::OnionMessageContents;
+use crate::routing::gossip::{NetworkGraph, NodeId};
+use super::packet::OnionMessageContents;
 use super::packet::ParsedOnionMessageContents;
 use super::offers::OffersMessageHandler;
 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
@@ -35,9 +34,19 @@ use crate::util::ser::Writeable;
 use core::fmt;
 use core::ops::Deref;
 use crate::io;
-use crate::sync::{Arc, Mutex};
+use crate::sync::Mutex;
 use crate::prelude::*;
 
+#[cfg(not(c_bindings))]
+use {
+       crate::sign::KeysManager,
+       crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager},
+       crate::ln::peer_handler::IgnoringMessageHandler,
+       crate::sync::Arc,
+};
+
+pub(super) const MAX_TIMER_TICKS: usize = 2;
+
 /// A sender, receiver and forwarder of [`OnionMessage`]s.
 ///
 /// # Handling Messages
@@ -60,11 +69,12 @@ use crate::prelude::*;
 /// # extern crate bitcoin;
 /// # use bitcoin::hashes::_export::_core::time::Duration;
 /// # use bitcoin::hashes::hex::FromHex;
-/// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
+/// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
 /// # use lightning::blinded_path::BlindedPath;
-/// # use lightning::sign::KeysManager;
+/// # use lightning::sign::{EntropySource, KeysManager};
 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
-/// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
+/// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
+/// # use lightning::onion_message::packet::OnionMessageContents;
 /// # use lightning::util::logger::{Logger, Record};
 /// # use lightning::util::ser::{Writeable, Writer};
 /// # use lightning::io;
@@ -83,8 +93,14 @@ use crate::prelude::*;
 /// #         Ok(OnionMessagePath {
 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 /// #             destination,
+/// #             first_node_addresses: None,
 /// #         })
 /// #     }
+/// #     fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
+/// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
+/// #     ) -> Result<Vec<BlindedPath>, ()> {
+/// #         unreachable!()
+/// #     }
 /// # }
 /// # let seed = [42u8; 32];
 /// # let time = Duration::from_secs(123456);
@@ -146,12 +162,12 @@ where
        L::Target: Logger,
        MR::Target: MessageRouter,
        OMH::Target: OffersMessageHandler,
-       CMH:: Target: CustomOnionMessageHandler,
+       CMH::Target: CustomOnionMessageHandler,
 {
        entropy_source: ES,
        node_signer: NS,
        logger: L,
-       message_buffers: Mutex<HashMap<PublicKey, OnionMessageBuffer>>,
+       message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
        secp_ctx: Secp256k1<secp256k1::All>,
        message_router: MR,
        offers_handler: OMH,
@@ -159,26 +175,31 @@ where
 }
 
 /// [`OnionMessage`]s buffered to be sent.
-enum OnionMessageBuffer {
+enum OnionMessageRecipient {
        /// Messages for a node connected as a peer.
        ConnectedPeer(VecDeque<OnionMessage>),
 
-       /// Messages for a node that is not yet connected.
-       PendingConnection(VecDeque<OnionMessage>),
+       /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
+       /// and tracked here.
+       PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 }
 
-impl OnionMessageBuffer {
+impl OnionMessageRecipient {
+       fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
+               Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
+       }
+
        fn pending_messages(&self) -> &VecDeque<OnionMessage> {
                match self {
-                       OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
-                       OnionMessageBuffer::PendingConnection(pending_messages) => pending_messages,
+                       OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
+                       OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
                }
        }
 
        fn enqueue_message(&mut self, message: OnionMessage) {
                let pending_messages = match self {
-                       OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
-                       OnionMessageBuffer::PendingConnection(pending_messages) => pending_messages,
+                       OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
+                       OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
                };
 
                pending_messages.push_back(message);
@@ -186,8 +207,8 @@ impl OnionMessageBuffer {
 
        fn dequeue_message(&mut self) -> Option<OnionMessage> {
                let pending_messages = match self {
-                       OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
-                       OnionMessageBuffer::PendingConnection(pending_messages) => {
+                       OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
+                       OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
                                debug_assert!(false);
                                pending_messages
                        },
@@ -199,18 +220,25 @@ impl OnionMessageBuffer {
        #[cfg(test)]
        fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
                let pending_messages = match self {
-                       OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
-                       OnionMessageBuffer::PendingConnection(pending_messages) => pending_messages,
+                       OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
+                       OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
                };
 
                core::mem::take(pending_messages)
        }
 
        fn mark_connected(&mut self) {
-               if let OnionMessageBuffer::PendingConnection(pending_messages) = self {
+               if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
                        let mut new_pending_messages = VecDeque::new();
                        core::mem::swap(pending_messages, &mut new_pending_messages);
-                       *self = OnionMessageBuffer::ConnectedPeer(new_pending_messages);
+                       *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
+               }
+       }
+
+       fn is_connected(&self) -> bool {
+               match self {
+                       OnionMessageRecipient::ConnectedPeer(..) => true,
+                       OnionMessageRecipient::PendingConnection(..) => false,
                }
        }
 }
@@ -236,7 +264,7 @@ pub struct PendingOnionMessage<T: OnionMessageContents> {
 ///
 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 /// enqueued for sending.
-pub type PendingOnionMessage<T: OnionMessageContents> = (T, Destination, Option<BlindedPath>);
+pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 
 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
        contents: T, destination: Destination, reply_path: Option<BlindedPath>
@@ -253,19 +281,119 @@ pub trait MessageRouter {
        fn find_path(
                &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
        ) -> Result<OnionMessagePath, ()>;
+
+       /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
+       /// direct peers with the `recipient`.
+       fn create_blinded_paths<
+               T: secp256k1::Signing + secp256k1::Verification
+       >(
+               &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+       ) -> Result<Vec<BlindedPath>, ()>;
 }
 
 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
-pub struct DefaultMessageRouter;
+pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref>
+where
+       L::Target: Logger,
+       ES::Target: EntropySource,
+{
+       network_graph: G,
+       entropy_source: ES,
+}
 
-impl MessageRouter for DefaultMessageRouter {
+impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> DefaultMessageRouter<G, L, ES>
+where
+       L::Target: Logger,
+       ES::Target: EntropySource,
+{
+       /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
+       pub fn new(network_graph: G, entropy_source: ES) -> Self {
+               Self { network_graph, entropy_source }
+       }
+}
+
+impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
+where
+       L::Target: Logger,
+       ES::Target: EntropySource,
+{
        fn find_path(
                &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
        ) -> Result<OnionMessagePath, ()> {
-               if peers.contains(&destination.first_node()) {
-                       Ok(OnionMessagePath { intermediate_nodes: vec![], destination })
+               let first_node = destination.first_node();
+               if peers.contains(&first_node) {
+                       Ok(OnionMessagePath {
+                               intermediate_nodes: vec![], destination, first_node_addresses: None
+                       })
                } else {
-                       Err(())
+                       let network_graph = self.network_graph.deref().read_only();
+                       let node_announcement = network_graph
+                               .node(&NodeId::from_pubkey(&first_node))
+                               .and_then(|node_info| node_info.announcement_info.as_ref())
+                               .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
+                               .map(|node_announcement| &node_announcement.contents);
+
+                       match node_announcement {
+                               Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
+                                       let first_node_addresses = Some(node_announcement.addresses.clone());
+                                       Ok(OnionMessagePath {
+                                               intermediate_nodes: vec![], destination, first_node_addresses
+                                       })
+                               },
+                               _ => Err(()),
+                       }
+               }
+       }
+
+       fn create_blinded_paths<
+               T: secp256k1::Signing + secp256k1::Verification
+       >(
+               &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+       ) -> Result<Vec<BlindedPath>, ()> {
+               // Limit the number of blinded paths that are computed.
+               const MAX_PATHS: usize = 3;
+
+               // Ensure peers have at least three channels so that it is more difficult to infer the
+               // recipient's node_id.
+               const MIN_PEER_CHANNELS: usize = 3;
+
+               let network_graph = self.network_graph.deref().read_only();
+               let is_recipient_announced =
+                       network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
+
+               let mut peer_info = peers.iter()
+                       // Limit to peers with announced channels
+                       .filter_map(|pubkey|
+                               network_graph
+                                       .node(&NodeId::from_pubkey(pubkey))
+                                       .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
+                                       .map(|info| (*pubkey, info.is_tor_only(), info.channels.len()))
+                       )
+                       // Exclude Tor-only nodes when the recipient is announced.
+                       .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
+                       .collect::<Vec<_>>();
+
+               // Prefer using non-Tor nodes with the most channels as the introduction node.
+               peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
+                       a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
+               });
+
+               let paths = peer_info.into_iter()
+                       .map(|(pubkey, _, _)| vec![pubkey, recipient])
+                       .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
+                       .take(MAX_PATHS)
+                       .collect::<Result<Vec<_>, _>>();
+
+               match paths {
+                       Ok(paths) if !paths.is_empty() => Ok(paths),
+                       _ => {
+                               if is_recipient_announced {
+                                       BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
+                                               .map(|path| vec![path])
+                               } else {
+                                       Err(())
+                               }
+                       },
                }
        }
 }
@@ -278,10 +406,26 @@ pub struct OnionMessagePath {
 
        /// The recipient of the message.
        pub destination: Destination,
+
+       /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
+       ///
+       /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
+       /// this to initiate such a connection.
+       pub first_node_addresses: Option<Vec<SocketAddress>>,
+}
+
+impl OnionMessagePath {
+       /// Returns the first node in the path.
+       pub fn first_node(&self) -> PublicKey {
+               self.intermediate_nodes
+                       .first()
+                       .copied()
+                       .unwrap_or_else(|| self.destination.first_node())
+       }
 }
 
 /// The destination of an onion message.
-#[derive(Clone)]
+#[derive(Clone, Hash, Debug, PartialEq, Eq)]
 pub enum Destination {
        /// We're sending this onion message to a node.
        Node(PublicKey),
@@ -308,17 +452,20 @@ impl Destination {
 /// Result of successfully [sending an onion message].
 ///
 /// [sending an onion message]: OnionMessenger::send_onion_message
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Clone, Hash, Debug, PartialEq, Eq)]
 pub enum SendSuccess {
        /// The message was buffered and will be sent once it is processed by
        /// [`OnionMessageHandler::next_onion_message_for_peer`].
        Buffered,
+       /// The message was buffered and will be sent once the node is connected as a peer and it is
+       /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
+       BufferedAwaitingConnection(PublicKey),
 }
 
 /// Errors that may occur when [sending an onion message].
 ///
 /// [sending an onion message]: OnionMessenger::send_onion_message
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Clone, Hash, Debug, PartialEq, Eq)]
 pub enum SendError {
        /// Errored computing onion message packet keys.
        Secp256k1(secp256k1::Error),
@@ -328,8 +475,8 @@ pub enum SendError {
        /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
        /// hops.
        TooFewBlindedHops,
-       /// Our next-hop peer was offline or does not support onion message forwarding.
-       InvalidFirstHop,
+       /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
+       InvalidFirstHop(PublicKey),
        /// A path from the sender to the destination could not be found by the [`MessageRouter`].
        PathNotFound,
        /// Onion message contents must have a TLV type >= 64.
@@ -388,6 +535,7 @@ pub trait CustomOnionMessageHandler {
 
 /// A processed incoming onion message, containing either a Forward (another onion message)
 /// or a Receive payload with decrypted contents.
+#[derive(Debug)]
 pub enum PeeledOnion<T: OnionMessageContents> {
        /// Forwarded onion, with the next node id and a new onion
        Forward(PublicKey, OnionMessage),
@@ -398,16 +546,17 @@ pub enum PeeledOnion<T: OnionMessageContents> {
 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 /// `path`.
 ///
-/// Returns both the node id of the peer to send the message to and the message itself.
+/// Returns the node id of the peer to send the message to, the message itself, and any addresses
+/// need to connect to the first node.
 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
        entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
        path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
-) -> Result<(PublicKey, OnionMessage), SendError>
+) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 where
        ES::Target: EntropySource,
        NS::Target: NodeSigner,
 {
-       let OnionMessagePath { intermediate_nodes, mut destination } = path;
+       let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
        if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
                if blinded_hops.is_empty() {
                        return Err(SendError::TooFewBlindedHops);
@@ -448,10 +597,8 @@ where
        let onion_routing_packet = construct_onion_message_packet(
                packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 
-       Ok((first_node_id, OnionMessage {
-               blinding_point,
-               onion_routing_packet
-       }))
+       let message = OnionMessage { blinding_point, onion_routing_packet };
+       Ok((first_node_id, message, first_node_addresses))
 }
 
 /// Decode one layer of an incoming [`OnionMessage`].
@@ -572,7 +719,7 @@ where
                OnionMessenger {
                        entropy_source,
                        node_signer,
-                       message_buffers: Mutex::new(HashMap::new()),
+                       message_recipients: Mutex::new(new_hash_map()),
                        secp_ctx,
                        logger,
                        message_router,
@@ -581,6 +728,11 @@ where
                }
        }
 
+       #[cfg(test)]
+       pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
+               self.offers_handler = offers_handler;
+       }
+
        /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
        ///
        /// See [`OnionMessenger`] for example usage.
@@ -612,6 +764,12 @@ where
                        Ok(SendSuccess::Buffered) => {
                                log_trace!(self.logger, "Buffered onion message {}", log_suffix);
                        },
+                       Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
+                               log_trace!(
+                                       self.logger, "Buffered onion message waiting on peer connection {}: {}",
+                                       log_suffix, node_id
+                               );
+                       },
                }
 
                result
@@ -622,9 +780,9 @@ where
                        .get_node_id(Recipient::Node)
                        .map_err(|_| SendError::GetNodeIdFailed)?;
 
-               let peers = self.message_buffers.lock().unwrap()
+               let peers = self.message_recipients.lock().unwrap()
                        .iter()
-                       .filter(|(_, buffer)| matches!(buffer, OnionMessageBuffer::ConnectedPeer(_)))
+                       .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
                        .map(|(node_id, _)| *node_id)
                        .collect();
 
@@ -639,31 +797,50 @@ where
        ) -> Result<SendSuccess, SendError> {
                log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 
-               let (first_node_id, onion_message) = create_onion_message(
+               let (first_node_id, onion_message, addresses) = create_onion_message(
                        &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
                )?;
 
-               let mut message_buffers = self.message_buffers.lock().unwrap();
-               if outbound_buffer_full(&first_node_id, &message_buffers) {
+               let mut message_recipients = self.message_recipients.lock().unwrap();
+               if outbound_buffer_full(&first_node_id, &message_recipients) {
                        return Err(SendError::BufferFull);
                }
 
-               match message_buffers.entry(first_node_id) {
-                       hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
+               match message_recipients.entry(first_node_id) {
+                       hash_map::Entry::Vacant(e) => match addresses {
+                               None => Err(SendError::InvalidFirstHop(first_node_id)),
+                               Some(addresses) => {
+                                       e.insert(OnionMessageRecipient::pending_connection(addresses))
+                                               .enqueue_message(onion_message);
+                                       Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
+                               },
+                       },
                        hash_map::Entry::Occupied(mut e) => {
                                e.get_mut().enqueue_message(onion_message);
-                               Ok(SendSuccess::Buffered)
+                               if e.get().is_connected() {
+                                       Ok(SendSuccess::Buffered)
+                               } else {
+                                       Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
+                               }
                        },
                }
        }
 
-       #[cfg(test)]
-       pub(super) fn send_onion_message_using_path<T: OnionMessageContents>(
+       #[cfg(any(test, feature = "_test_utils"))]
+       pub fn send_onion_message_using_path<T: OnionMessageContents>(
                &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
        ) -> Result<SendSuccess, SendError> {
                self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
        }
 
+       pub(crate) fn peel_onion_message(
+               &self, msg: &OnionMessage
+       ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
+               peel_onion_message(
+                       msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
+               )
+       }
+
        fn handle_onion_message_response<T: OnionMessageContents>(
                &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
        ) {
@@ -683,18 +860,18 @@ where
 
        #[cfg(test)]
        pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
-               let mut message_buffers = self.message_buffers.lock().unwrap();
-               let mut msgs = HashMap::new();
+               let mut message_recipients = self.message_recipients.lock().unwrap();
+               let mut msgs = new_hash_map();
                // We don't want to disconnect the peers by removing them entirely from the original map, so we
                // release the pending message buffers individually.
-               for (peer_node_id, buffer) in &mut *message_buffers {
-                       msgs.insert(*peer_node_id, buffer.release_pending_messages());
+               for (node_id, recipient) in &mut *message_recipients {
+                       msgs.insert(*node_id, recipient.release_pending_messages());
                }
                msgs
        }
 }
 
-fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageBuffer>) -> bool {
+fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
        const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
        const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
        let mut total_buffered_bytes = 0;
@@ -717,6 +894,27 @@ fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, On
        false
 }
 
+impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
+for OnionMessenger<ES, NS, L, MR, OMH, CMH>
+where
+       ES::Target: EntropySource,
+       NS::Target: NodeSigner,
+       L::Target: Logger,
+       MR::Target: MessageRouter,
+       OMH::Target: OffersMessageHandler,
+       CMH::Target: CustomOnionMessageHandler,
+{
+       fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
+               for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
+                       if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
+                               if let Some(addresses) = addresses.take() {
+                                       handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
+                               }
+                       }
+               }
+       }
+}
+
 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 where
@@ -728,9 +926,7 @@ where
        CMH::Target: CustomOnionMessageHandler,
 {
        fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
-               match peel_onion_message(
-                       msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
-               ) {
+               match self.peel_onion_message(msg) {
                        Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
                                log_trace!(
                                        self.logger,
@@ -759,26 +955,26 @@ where
                                }
                        },
                        Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
-                               let mut message_buffers = self.message_buffers.lock().unwrap();
-                               if outbound_buffer_full(&next_node_id, &message_buffers) {
-                                       log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
+                               let mut message_recipients = self.message_recipients.lock().unwrap();
+                               if outbound_buffer_full(&next_node_id, &message_recipients) {
+                                       log_trace!(self.logger, "Dropping forwarded onion message to peer {}: outbound buffer full", next_node_id);
                                        return
                                }
 
                                #[cfg(fuzzing)]
-                               message_buffers
+                               message_recipients
                                        .entry(next_node_id)
-                                       .or_insert_with(|| OnionMessageBuffer::ConnectedPeer(VecDeque::new()));
+                                       .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
 
-                               match message_buffers.entry(next_node_id) {
+                               match message_recipients.entry(next_node_id) {
                                        hash_map::Entry::Occupied(mut e) if matches!(
-                                               e.get(), OnionMessageBuffer::ConnectedPeer(..)
+                                               e.get(), OnionMessageRecipient::ConnectedPeer(..)
                                        ) => {
                                                e.get_mut().enqueue_message(onion_message);
                                                log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
                                        },
                                        _ => {
-                                               log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
+                                               log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {}", next_node_id);
                                                return
                                        },
                                }
@@ -791,21 +987,42 @@ where
 
        fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
                if init.features.supports_onion_messages() {
-                       self.message_buffers.lock().unwrap()
+                       self.message_recipients.lock().unwrap()
                                .entry(*their_node_id)
-                               .or_insert_with(|| OnionMessageBuffer::ConnectedPeer(VecDeque::new()))
+                               .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
                                .mark_connected();
                } else {
-                       self.message_buffers.lock().unwrap().remove(their_node_id);
+                       self.message_recipients.lock().unwrap().remove(their_node_id);
                }
 
                Ok(())
        }
 
        fn peer_disconnected(&self, their_node_id: &PublicKey) {
-               match self.message_buffers.lock().unwrap().remove(their_node_id) {
-                       Some(OnionMessageBuffer::ConnectedPeer(..)) => {},
-                       _ => debug_assert!(false),
+               match self.message_recipients.lock().unwrap().remove(their_node_id) {
+                       Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
+                       Some(_) => debug_assert!(false),
+                       None => {},
+               }
+       }
+
+       fn timer_tick_occurred(&self) {
+               let mut message_recipients = self.message_recipients.lock().unwrap();
+
+               // Drop any pending recipients since the last call to avoid retaining buffered messages for
+               // too long.
+               message_recipients.retain(|_, recipient| match recipient {
+                       OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
+                       OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
+                       _ => true,
+               });
+
+               // Increment a timer tick for pending recipients so that their buffered messages are dropped
+               // at MAX_TIMER_TICKS.
+               for recipient in message_recipients.values_mut() {
+                       if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
+                               *ticks += 1;
+                       }
                }
        }
 
@@ -847,7 +1064,7 @@ where
                        );
                }
 
-               self.message_buffers.lock().unwrap()
+               self.message_recipients.lock().unwrap()
                        .get_mut(&peer_node_id)
                        .and_then(|buffer| buffer.dequeue_message())
        }
@@ -867,7 +1084,7 @@ pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
        Arc<KeysManager>,
        Arc<KeysManager>,
        Arc<L>,
-       Arc<DefaultMessageRouter>,
+       Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
        Arc<SimpleArcChannelManager<M, T, F, L>>,
        IgnoringMessageHandler
 >;
@@ -886,7 +1103,7 @@ pub type SimpleRefOnionMessenger<
        &'a KeysManager,
        &'a KeysManager,
        &'b L,
-       &'i DefaultMessageRouter,
+       &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
        &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
        IgnoringMessageHandler
 >;