Add empty OnionMessenger, OnionMessageHandler trait, and boilerplate

This fills in the boilerplate needed to hook up the OnionMessenger to send and
receive messages through the PeerManager. It also sets up the OnionMessenger
and its struct fields.

Author: valentinewallace

fuzz/src/full_stack.rs

@@ -163,7 +163,7 @@ type ChannelMan = ChannelManager<
 	EnforcingSigner,
 	Arc<chainmonitor::ChainMonitor<EnforcingSigner, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>, Arc<TestPersister>>>,
 	Arc<TestBroadcaster>, Arc<KeyProvider>, Arc<FuzzEstimator>, Arc<dyn Logger>>;
-type PeerMan<'a> = PeerManager<Peer<'a>, Arc<ChannelMan>, Arc<P2PGossipSync<Arc<NetworkGraph>, Arc<dyn chain::Access>, Arc<dyn Logger>>>, Arc<dyn Logger>, IgnoringMessageHandler>;
+type PeerMan<'a> = PeerManager<Peer<'a>, Arc<ChannelMan>, Arc<P2PGossipSync<Arc<NetworkGraph>, Arc<dyn chain::Access>, Arc<dyn Logger>>>, IgnoringMessageHandler, Arc<dyn Logger>, IgnoringMessageHandler>;
 
 struct MoneyLossDetector<'a> {
 	manager: Arc<ChannelMan>,
@@ -403,6 +403,7 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
 	let mut loss_detector = MoneyLossDetector::new(&peers, channelmanager.clone(), monitor.clone(), PeerManager::new(MessageHandler {
 		chan_handler: channelmanager.clone(),
 		route_handler: gossip_sync.clone(),
+		onion_message_handler: IgnoringMessageHandler {},
 	}, our_network_key, &[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15, 0], Arc::clone(&logger), IgnoringMessageHandler{}));
 
 	let mut should_forward = false;

lightning-background-processor/src/lib.rs

@@ -16,7 +16,7 @@ use lightning::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use lightning::chain::chainmonitor::{ChainMonitor, Persist};
 use lightning::chain::keysinterface::{Sign, KeysInterface};
 use lightning::ln::channelmanager::ChannelManager;
-use lightning::ln::msgs::{ChannelMessageHandler, RoutingMessageHandler};
+use lightning::ln::msgs::{ChannelMessageHandler, OnionMessageHandler, RoutingMessageHandler};
 use lightning::ln::peer_handler::{CustomMessageHandler, PeerManager, SocketDescriptor};
 use lightning::routing::gossip::{NetworkGraph, P2PGossipSync};
 use lightning::routing::scoring::WriteableScore;
@@ -178,14 +178,15 @@ impl BackgroundProcessor {
 		P: 'static + Deref + Send + Sync,
 		Descriptor: 'static + SocketDescriptor + Send + Sync,
 		CMH: 'static + Deref + Send + Sync,
+		OMH: 'static + Deref + Send + Sync,
 		RMH: 'static + Deref + Send + Sync,
 		EH: 'static + EventHandler + Send,
 		PS: 'static + Deref + Send,
 		M: 'static + Deref<Target = ChainMonitor<Signer, CF, T, F, L, P>> + Send + Sync,
 		CM: 'static + Deref<Target = ChannelManager<Signer, CW, T, K, F, L>> + Send + Sync,
 		PGS: 'static + Deref<Target = P2PGossipSync<G, CA, L>> + Send + Sync,
 		UMH: 'static + Deref + Send + Sync,
-		PM: 'static + Deref<Target = PeerManager<Descriptor, CMH, RMH, L, UMH>> + Send + Sync,
+		PM: 'static + Deref<Target = PeerManager<Descriptor, CMH, RMH, OMH, L, UMH>> + Send + Sync,
 		S: 'static + Deref<Target = SC> + Send + Sync,
 		SC: WriteableScore<'a>,
 		RGS: 'static + Deref<Target = RapidGossipSync<G>> + Send
@@ -204,6 +205,7 @@ impl BackgroundProcessor {
 		L::Target: 'static + Logger,
 		P::Target: 'static + Persist<Signer>,
 		CMH::Target: 'static + ChannelMessageHandler,
+		OMH::Target: 'static + OnionMessageHandler,
 		RMH::Target: 'static + RoutingMessageHandler,
 		UMH::Target: 'static + CustomMessageHandler,
 		PS::Target: 'static + Persister<'a, Signer, CW, T, K, F, L, SC>,
@@ -443,7 +445,9 @@ mod tests {
 	struct Node {
 		node: Arc<SimpleArcChannelManager<ChainMonitor, test_utils::TestBroadcaster, test_utils::TestFeeEstimator, test_utils::TestLogger>>,
 		p2p_gossip_sync: Option<Arc<P2PGossipSync<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>>>,
-		peer_manager: Arc<PeerManager<TestDescriptor, Arc<test_utils::TestChannelMessageHandler>, Arc<test_utils::TestRoutingMessageHandler>, Arc<test_utils::TestLogger>, IgnoringMessageHandler>>,
+		peer_manager: Arc<PeerManager<TestDescriptor, Arc<test_utils::TestChannelMessageHandler>, Arc<test_utils::TestRoutingMessageHandler>, IgnoringMessageHandler, Arc<test_utils::TestLogger>, IgnoringMessageHandler>>,
+		// net_graph_msg_handler: Option<Arc<NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>>>,
+		// peer_manager: Arc<PeerManager<TestDescriptor, Arc<test_utils::TestChannelMessageHandler>, Arc<test_utils::TestRoutingMessageHandler>, IgnoringMessageHandler, Arc<test_utils::TestLogger>, IgnoringMessageHandler>>,
 		chain_monitor: Arc<ChainMonitor>,
 		persister: Arc<FilesystemPersister>,
 		tx_broadcaster: Arc<test_utils::TestBroadcaster>,
@@ -548,7 +552,9 @@ mod tests {
 			let manager = Arc::new(ChannelManager::new(fee_estimator.clone(), chain_monitor.clone(), tx_broadcaster.clone(), logger.clone(), keys_manager.clone(), UserConfig::default(), params));
 			let network_graph = Arc::new(NetworkGraph::new(genesis_block.header.block_hash()));
 			let p2p_gossip_sync = Some(Arc::new(P2PGossipSync::new(network_graph.clone(), Some(chain_source.clone()), logger.clone())));
-			let msg_handler = MessageHandler { chan_handler: Arc::new(test_utils::TestChannelMessageHandler::new()), route_handler: Arc::new(test_utils::TestRoutingMessageHandler::new() )};
+			let msg_handler = MessageHandler { chan_handler: Arc::new(test_utils::TestChannelMessageHandler::new()), route_handler: Arc::new(test_utils::TestRoutingMessageHandler::new() ), onion_message_handler: IgnoringMessageHandler{}};
+			// let net_graph_msg_handler = Some(Arc::new(NetGraphMsgHandler::new(network_graph.clone(), Some(chain_source.clone()), logger.clone())));
+			// let msg_handler = MessageHandler { chan_handler: Arc::new(test_utils::TestChannelMessageHandler::new()), route_handler: Arc::new(test_utils::TestRoutingMessageHandler::new()), onion_message_handler: IgnoringMessageHandler{}};
 			let peer_manager = Arc::new(PeerManager::new(msg_handler, keys_manager.get_node_secret(Recipient::Node).unwrap(), &seed, logger.clone(), IgnoringMessageHandler{}));
 			let scorer = Arc::new(Mutex::new(test_utils::TestScorer::with_penalty(0)));
 			let rapid_gossip_sync = None;

lightning-net-tokio/src/lib.rs

@@ -81,7 +81,7 @@ use tokio::io::{AsyncReadExt, AsyncWrite, AsyncWriteExt};
 use lightning::ln::peer_handler;
 use lightning::ln::peer_handler::SocketDescriptor as LnSocketTrait;
 use lightning::ln::peer_handler::CustomMessageHandler;
-use lightning::ln::msgs::{ChannelMessageHandler, RoutingMessageHandler, NetAddress};
+use lightning::ln::msgs::{ChannelMessageHandler, OnionMessageHandler, NetAddress, RoutingMessageHandler};
 use lightning::util::logger::Logger;
 
 use std::task;
@@ -120,9 +120,10 @@ struct Connection {
 	id: u64,
 }
 impl Connection {
-	async fn poll_event_process<CMH, RMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>, Arc<UMH>>>, mut event_receiver: mpsc::Receiver<()>) where
+	async fn poll_event_process<CMH, RMH, OMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<OMH>, Arc<L>, Arc<UMH>>>, mut event_receiver: mpsc::Receiver<()>) where
 			CMH: ChannelMessageHandler + 'static + Send + Sync,
 			RMH: RoutingMessageHandler + 'static + Send + Sync,
+			OMH: OnionMessageHandler + 'static + Send + Sync,
 			L: Logger + 'static + ?Sized + Send + Sync,
 			UMH: CustomMessageHandler + 'static + Send + Sync {
 		loop {
@@ -133,9 +134,10 @@ impl Connection {
 		}
 	}
 
-	async fn schedule_read<CMH, RMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>, Arc<UMH>>>, us: Arc<Mutex<Self>>, mut reader: io::ReadHalf<TcpStream>, mut read_wake_receiver: mpsc::Receiver<()>, mut write_avail_receiver: mpsc::Receiver<()>) where
+	async fn schedule_read<CMH, RMH, OMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<OMH>, Arc<L>, Arc<UMH>>>, us: Arc<Mutex<Self>>, mut reader: io::ReadHalf<TcpStream>, mut read_wake_receiver: mpsc::Receiver<()>, mut write_avail_receiver: mpsc::Receiver<()>) where
 			CMH: ChannelMessageHandler + 'static + Send + Sync,
 			RMH: RoutingMessageHandler + 'static + Send + Sync,
+			OMH: OnionMessageHandler + 'static + Send + Sync,
 			L: Logger + 'static + ?Sized + Send + Sync,
 			UMH: CustomMessageHandler + 'static + Send + Sync {
 		// Create a waker to wake up poll_event_process, above
@@ -255,9 +257,10 @@ fn get_addr_from_stream(stream: &StdTcpStream) -> Option<NetAddress> {
 /// 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<CMH, RMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>, Arc<UMH>>>, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
+pub fn setup_inbound<CMH, RMH, OMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<OMH>, Arc<L>, Arc<UMH>>>, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
 		CMH: ChannelMessageHandler + 'static + Send + Sync,
 		RMH: RoutingMessageHandler + 'static + Send + Sync,
+		OMH: OnionMessageHandler + 'static + Send + Sync,
 		L: Logger + 'static + ?Sized + Send + Sync,
 		UMH: CustomMessageHandler + 'static + Send + Sync {
 	let remote_addr = get_addr_from_stream(&stream);
@@ -297,9 +300,10 @@ pub fn setup_inbound<CMH, RMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManag
 /// 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<CMH, RMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>, Arc<UMH>>>, their_node_id: PublicKey, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
+pub fn setup_outbound<CMH, RMH, OMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<OMH>, Arc<L>, Arc<UMH>>>, their_node_id: PublicKey, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
 		CMH: ChannelMessageHandler + 'static + Send + Sync,
 		RMH: RoutingMessageHandler + 'static + Send + Sync,
+		OMH: OnionMessageHandler + 'static + Send + Sync,
 		L: Logger + 'static + ?Sized + Send + Sync,
 		UMH: CustomMessageHandler + 'static + Send + Sync {
 	let remote_addr = get_addr_from_stream(&stream);
@@ -368,9 +372,10 @@ pub fn setup_outbound<CMH, RMH, L, UMH>(peer_manager: Arc<peer_handler::PeerMana
 /// 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<CMH, RMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>, Arc<UMH>>>, their_node_id: PublicKey, addr: SocketAddr) -> Option<impl std::future::Future<Output=()>> where
+pub async fn connect_outbound<CMH, RMH, OMH, L, UMH>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<OMH>, Arc<L>, Arc<UMH>>>, their_node_id: PublicKey, addr: SocketAddr) -> Option<impl std::future::Future<Output=()>> where
 		CMH: ChannelMessageHandler + 'static + Send + Sync,
 		RMH: RoutingMessageHandler + 'static + Send + Sync,
+		OMH: OnionMessageHandler + 'static + Send + Sync,
 		L: Logger + 'static + ?Sized + Send + Sync,
 		UMH: CustomMessageHandler + 'static + Send + Sync {
 	if let Ok(Ok(stream)) = time::timeout(Duration::from_secs(10), async { TcpStream::connect(&addr).await.map(|s| s.into_std().unwrap()) }).await {
@@ -618,6 +623,7 @@ mod tests {
 		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{}),
 		}, a_key.clone(), &[1; 32], Arc::new(TestLogger()), Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{})));
 
 		let (b_connected_sender, mut b_connected) = mpsc::channel(1);
@@ -632,6 +638,7 @@ mod tests {
 		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{}),
 		}, b_key.clone(), &[2; 32], Arc::new(TestLogger()), Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{})));
 
 		// We bind on localhost, hoping the environment is properly configured with a local
@@ -683,6 +690,7 @@ mod tests {
 
 		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{}),
 		}, a_key, &[1; 32], Arc::new(TestLogger()), Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler{})));
 

lightning/src/ln/channelmanager.rs

@@ -5892,6 +5892,7 @@ impl<Signer: Sign, M: Deref , T: Deref , K: Deref , F: Deref , L: Deref >
 					&events::MessageSendEvent::SendShortIdsQuery { .. } => false,
 					&events::MessageSendEvent::SendReplyChannelRange { .. } => false,
 					&events::MessageSendEvent::SendGossipTimestampFilter { .. } => false,
+					&events::MessageSendEvent::SendOnionMessage { .. } => false,
 				}
 			});
 		}

lightning/src/ln/msgs.rs

@@ -31,6 +31,7 @@ use bitcoin::blockdata::script::Script;
 use bitcoin::hash_types::{Txid, BlockHash};
 
 use ln::features::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
+use ln::onion_message;
 
 use prelude::*;
 use core::fmt;
@@ -40,7 +41,7 @@ use io_extras::read_to_end;
 
 use util::events::MessageSendEventsProvider;
 use util::logger;
-use util::ser::{Readable, Writeable, Writer, FixedLengthReader, HighZeroBytesDroppedVarInt};
+use util::ser::{Readable, ReadableArgs, Writeable, Writer, FixedLengthReader, HighZeroBytesDroppedVarInt};
 
 use ln::{PaymentPreimage, PaymentHash, PaymentSecret};
 
@@ -304,6 +305,16 @@ pub struct UpdateAddHTLC {
 	pub(crate) onion_routing_packet: OnionPacket,
 }
 
+ /// An onion message to be sent or received from a peer
+#[derive(Clone, Debug, PartialEq)]
+pub struct OnionMessage {
+	/// This blinding point is used in the shared secret that is used to decrypt the onion message
+	/// payload's `encrypted_data` field.
+	pub(crate) blinding_point: PublicKey,
+	pub(crate) len: u16,
+	pub(crate) onion_routing_packet: onion_message::Packet,
+}
+
 /// An update_fulfill_htlc message to be sent or received from a peer
 #[derive(Clone, Debug, PartialEq)]
 pub struct UpdateFulfillHTLC {
@@ -912,6 +923,12 @@ pub trait RoutingMessageHandler : MessageSendEventsProvider {
 	fn handle_query_short_channel_ids(&self, their_node_id: &PublicKey, msg: QueryShortChannelIds) -> Result<(), LightningError>;
 }
 
+/// A trait to describe an object that can receive onion messages.
+pub trait OnionMessageHandler : MessageSendEventsProvider {
+	/// Handle an incoming onion_message message from the given peer.
+	fn handle_onion_message(&self, their_node_id: &PublicKey, msg: &OnionMessage);
+}
+
 mod fuzzy_internal_msgs {
 	use prelude::*;
 	use ln::{PaymentPreimage, PaymentSecret};
@@ -1304,6 +1321,28 @@ impl_writeable_msg!(UpdateAddHTLC, {
 	onion_routing_packet
 }, {});
 
+impl Readable for OnionMessage {
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+		let blinding_point: PublicKey = Readable::read(r)?;
+		let len: u16 = Readable::read(r)?;
+		let onion_routing_packet: onion_message::Packet = <onion_message::Packet as ReadableArgs<u16>>::read(r, len)?;
+		Ok(Self {
+			blinding_point,
+			len,
+			onion_routing_packet,
+		})
+	}
+}
+
+impl Writeable for OnionMessage {
+	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+		self.blinding_point.write(w)?;
+		self.len.write(w)?;
+		self.onion_routing_packet.write(w)?;
+		Ok(())
+	}
+}
+
 impl Writeable for FinalOnionHopData {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 		self.payment_secret.0.write(w)?;

lightning/src/ln/onion_message.rs

@@ -14,15 +14,19 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
 use bitcoin::secp256k1::ecdh::SharedSecret;
 
-use chain::keysinterface::{KeysInterface, Sign};
-use ln::msgs::DecodeError;
+use chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Sign};
+use ln::msgs::{self, DecodeError, OnionMessageHandler};
 use ln::onion_utils;
 use util::chacha20poly1305rfc::{ChaCha20Poly1305RFC, ChaChaPoly1305Writer};
+use util::events::{MessageSendEvent, MessageSendEventsProvider};
+use util::logger::Logger;
 use util::ser::{Readable, ReadableArgs, VecWriter, Writeable, Writer};
 
+use core::mem;
 use core::ops::Deref;
 use io::{self, Read};
 use prelude::*;
+use sync::{Arc, Mutex};
 
 #[derive(Clone, Debug, PartialEq)]
 pub(crate) struct Packet {
@@ -239,6 +243,58 @@ impl BlindedRoute {
 	}
 }
 
+/// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
+/// used to retrieve invoices and fulfill invoice requests from offers.
+pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
+	where K::Target: KeysInterface<Signer = Signer>,
+				L::Target: Logger,
+{
+	keys_manager: K,
+	logger: L,
+	pending_msg_events: Mutex<Vec<MessageSendEvent>>,
+	secp_ctx: Secp256k1<secp256k1::All>,
+	// Coming soon:
+	// invoice_handler: InvoiceHandler,
+	// custom_handler: CustomHandler, // handles custom onion messages
+}
+
+impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
+	where K::Target: KeysInterface<Signer = Signer>,
+				L::Target: Logger,
+{
+	/// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
+	/// their respective handlers.
+	pub fn new(keys_manager: K, logger: L) -> Self {
+		let mut secp_ctx = Secp256k1::new();
+		secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
+		OnionMessenger {
+			keys_manager,
+			pending_msg_events: Mutex::new(Vec::new()),
+			secp_ctx,
+			logger,
+		}
+	}
+}
+
+impl<Signer: Sign, K: Deref, L: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L>
+	where K::Target: KeysInterface<Signer = Signer>,
+				L::Target: Logger,
+{
+	fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {}
+}
+
+impl<Signer: Sign, K: Deref, L: Deref> MessageSendEventsProvider for OnionMessenger<Signer, K, L>
+	where K::Target: KeysInterface<Signer = Signer>,
+				L::Target: Logger,
+{
+	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
+		let mut pending_msg_events = self.pending_msg_events.lock().unwrap();
+		let mut ret = Vec::new();
+		mem::swap(&mut ret, &mut *pending_msg_events);
+		ret
+	}
+}
+
 #[allow(unused_assignments)]
 #[inline]
 fn construct_keys_callback<T: secp256k1::Signing + secp256k1::Verification, FType: FnMut(PublicKey, SharedSecret, [u8; 32], PublicKey, SharedSecret)> (secp_ctx: &Secp256k1<T>, unblinded_path: &Vec<PublicKey>, session_priv: &SecretKey, mut callback: FType) -> Result<(), secp256k1::Error> {
@@ -310,3 +366,10 @@ fn construct_blinded_route_keys<T: secp256k1::Signing + secp256k1::Verification>
 
 	Ok((encrypted_data_keys, blinded_node_pks))
 }
+
+/// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
+/// [`SimpleArcPeerManager`]. See their docs for more details.
+pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>>;
+/// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
+/// [`SimpleRefPeerManager`]. See their docs for more details.
+pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L>;