Generalize CustomOnionMessageContents trait

Rename CustomOnionMessageContents to OnionMessageContents and use it as
a trait bound on messages passed to OnionMessenger methods. This allows
using the trait in an upcoming commit as a bound on the contents of
PendingOnionMessage.

Also, make ParsedOnionMessageContent implement OnionMessageContents so
that Payload can be bounded by OnionMessageContents directly, but used
when either reading a ParsedOnionMessageContent or writing a specific
type of OnionMessageContents (e.g., OffersMessage).

fuzz/src/onion_message.rs

@@ -14,7 +14,7 @@ use lightning::offers::invoice_request::UnsignedInvoiceRequest;
 use lightning::util::test_channel_signer::TestChannelSigner;
 use lightning::util::logger::Logger;
 use lightning::util::ser::{Readable, Writeable, Writer};
-use lightning::onion_message::{CustomOnionMessageContents, CustomOnionMessageHandler, Destination, MessageRouter, OffersMessage, OffersMessageHandler, OnionMessagePath, OnionMessenger};
+use lightning::onion_message::{CustomOnionMessageHandler, Destination, MessageRouter, OffersMessage, OffersMessageHandler, OnionMessageContents, OnionMessagePath, OnionMessenger};
 
 use crate::utils::test_logger;
 
@@ -84,7 +84,7 @@ struct TestCustomMessage {}
 const CUSTOM_MESSAGE_TYPE: u64 = 4242;
 const CUSTOM_MESSAGE_CONTENTS: [u8; 32] = [42; 32];
 
-impl CustomOnionMessageContents for TestCustomMessage {
+impl OnionMessageContents for TestCustomMessage {
 	fn tlv_type(&self) -> u64 {
 		CUSTOM_MESSAGE_TYPE
 	}
@@ -216,9 +216,9 @@ mod tests {
 			assert_eq!(log_entries.get(&("lightning::onion_message::messenger".to_string(),
 						"Received an onion message with path_id None and a reply_path".to_string())), Some(&1));
 			assert_eq!(log_entries.get(&("lightning::onion_message::messenger".to_string(),
-						"Sending onion message when responding to onion message with path_id None".to_string())), Some(&1));
+						"Sending onion message when responding to Custom onion message with path_id None".to_string())), Some(&1));
 			assert_eq!(log_entries.get(&("lightning::onion_message::messenger".to_string(),
-						"Failed sending onion message when responding to onion message with path_id None: TooFewBlindedHops".to_string())), Some(&1));
+						"Failed sending onion message when responding to Custom onion message with path_id None: TooFewBlindedHops".to_string())), Some(&1));
 		}
 
 		let two_unblinded_hops_om = "020000000000000000000000000000000000000000000000000000000000000e01055600020000000000000000000000000000000000000000000000000000000000000e0135043304210202020202020202020202020202020202020202020202020202020202020202026d000000000000000000000000000000eb0000000000000000000000000000000000000000000000000000000000000036041096000000000000000000000000000000fd1092202a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000004800000000000000000000000000000000000000000000000000000000000000";

lightning/src/ln/peer_handler.rs

@@ -29,7 +29,7 @@ use crate::util::ser::{VecWriter, Writeable, Writer};
 use crate::ln::peer_channel_encryptor::{PeerChannelEncryptor,NextNoiseStep};
 use crate::ln::wire;
 use crate::ln::wire::{Encode, Type};
-use crate::onion_message::{CustomOnionMessageContents, CustomOnionMessageHandler, OffersMessage, OffersMessageHandler, SimpleArcOnionMessenger, SimpleRefOnionMessenger};
+use crate::onion_message::{CustomOnionMessageHandler, OffersMessage, OffersMessageHandler, OnionMessageContents, SimpleArcOnionMessenger, SimpleRefOnionMessenger};
 use crate::routing::gossip::{NetworkGraph, P2PGossipSync, NodeId, NodeAlias};
 use crate::util::atomic_counter::AtomicCounter;
 use crate::util::logger::Logger;
@@ -131,7 +131,7 @@ impl CustomOnionMessageHandler for IgnoringMessageHandler {
 	}
 }
 
-impl CustomOnionMessageContents for Infallible {
+impl OnionMessageContents for Infallible {
 	fn tlv_type(&self) -> u64 { unreachable!(); }
 }
 

lightning/src/onion_message/functional_tests.rs

@@ -15,7 +15,7 @@ use crate::ln::msgs::{self, DecodeError, OnionMessageHandler};
 use crate::sign::{NodeSigner, Recipient};
 use crate::util::ser::{FixedLengthReader, LengthReadable, Writeable, Writer};
 use crate::util::test_utils;
-use super::{CustomOnionMessageContents, CustomOnionMessageHandler, Destination, MessageRouter, OffersMessage, OffersMessageHandler, ParsedOnionMessageContents, OnionMessagePath, OnionMessenger, SendError};
+use super::{CustomOnionMessageHandler, Destination, MessageRouter, OffersMessage, OffersMessageHandler, OnionMessageContents, OnionMessagePath, OnionMessenger, SendError};
 
 use bitcoin::network::constants::Network;
 use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
@@ -77,7 +77,7 @@ const CUSTOM_RESPONSE_MESSAGE_TYPE: u64 = 4343;
 const CUSTOM_REQUEST_MESSAGE_CONTENTS: [u8; 32] = [42; 32];
 const CUSTOM_RESPONSE_MESSAGE_CONTENTS: [u8; 32] = [43; 32];
 
-impl CustomOnionMessageContents for TestCustomMessage {
+impl OnionMessageContents for TestCustomMessage {
 	fn tlv_type(&self) -> u64 {
 		match self {
 			TestCustomMessage::Request => CUSTOM_REQUEST_MESSAGE_TYPE,
@@ -196,7 +196,7 @@ fn pass_along_path(path: &Vec<MessengerNode>) {
 #[test]
 fn one_hop() {
 	let nodes = create_nodes(2);
-	let test_msg = ParsedOnionMessageContents::Custom(TestCustomMessage::Response);
+	let test_msg = TestCustomMessage::Response;
 
 	let path = OnionMessagePath {
 		intermediate_nodes: vec![],
@@ -210,7 +210,7 @@ fn one_hop() {
 #[test]
 fn two_unblinded_hops() {
 	let nodes = create_nodes(3);
-	let test_msg = ParsedOnionMessageContents::Custom(TestCustomMessage::Response);
+	let test_msg = TestCustomMessage::Response;
 
 	let path = OnionMessagePath {
 		intermediate_nodes: vec![nodes[1].get_node_pk()],
@@ -224,7 +224,7 @@ fn two_unblinded_hops() {
 #[test]
 fn two_unblinded_two_blinded() {
 	let nodes = create_nodes(5);
-	let test_msg = ParsedOnionMessageContents::Custom(TestCustomMessage::Response);
+	let test_msg = TestCustomMessage::Response;
 
 	let secp_ctx = Secp256k1::new();
 	let blinded_path = BlindedPath::new_for_message(&[nodes[3].get_node_pk(), nodes[4].get_node_pk()], &*nodes[4].keys_manager, &secp_ctx).unwrap();
@@ -241,7 +241,7 @@ fn two_unblinded_two_blinded() {
 #[test]
 fn three_blinded_hops() {
 	let nodes = create_nodes(4);
-	let test_msg = ParsedOnionMessageContents::Custom(TestCustomMessage::Response);
+	let test_msg = TestCustomMessage::Response;
 
 	let secp_ctx = Secp256k1::new();
 	let blinded_path = BlindedPath::new_for_message(&[nodes[1].get_node_pk(), nodes[2].get_node_pk(), nodes[3].get_node_pk()], &*nodes[3].keys_manager, &secp_ctx).unwrap();
@@ -259,7 +259,7 @@ fn three_blinded_hops() {
 fn too_big_packet_error() {
 	// Make sure we error as expected if a packet is too big to send.
 	let nodes = create_nodes(2);
-	let test_msg = ParsedOnionMessageContents::Custom(TestCustomMessage::Response);
+	let test_msg = TestCustomMessage::Response;
 
 	let hop_node_id = nodes[1].get_node_pk();
 	let hops = vec![hop_node_id; 400];
@@ -285,7 +285,7 @@ fn we_are_intro_node() {
 		destination: Destination::BlindedPath(blinded_path),
 	};
 
-	nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg.clone()), None).unwrap();
+	nodes[0].messenger.send_onion_message(path, test_msg.clone(), None).unwrap();
 	nodes[2].custom_message_handler.expect_message(TestCustomMessage::Response);
 	pass_along_path(&nodes);
 
@@ -295,7 +295,7 @@ fn we_are_intro_node() {
 		intermediate_nodes: vec![],
 		destination: Destination::BlindedPath(blinded_path),
 	};
-	nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg), None).unwrap();
+	nodes[0].messenger.send_onion_message(path, test_msg, None).unwrap();
 	nodes[1].custom_message_handler.expect_message(TestCustomMessage::Response);
 	nodes.remove(2);
 	pass_along_path(&nodes);
@@ -315,7 +315,7 @@ fn invalid_blinded_path_error() {
 		intermediate_nodes: vec![],
 		destination: Destination::BlindedPath(blinded_path),
 	};
-	let err = nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg.clone()), None).unwrap_err();
+	let err = nodes[0].messenger.send_onion_message(path, test_msg.clone(), None).unwrap_err();
 	assert_eq!(err, SendError::TooFewBlindedHops);
 
 	// 1 hop
@@ -326,7 +326,7 @@ fn invalid_blinded_path_error() {
 		intermediate_nodes: vec![],
 		destination: Destination::BlindedPath(blinded_path),
 	};
-	let err = nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg), None).unwrap_err();
+	let err = nodes[0].messenger.send_onion_message(path, test_msg, None).unwrap_err();
 	assert_eq!(err, SendError::TooFewBlindedHops);
 }
 
@@ -342,7 +342,7 @@ fn reply_path() {
 		destination: Destination::Node(nodes[3].get_node_pk()),
 	};
 	let reply_path = BlindedPath::new_for_message(&[nodes[2].get_node_pk(), nodes[1].get_node_pk(), nodes[0].get_node_pk()], &*nodes[0].keys_manager, &secp_ctx).unwrap();
-	nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg.clone()), Some(reply_path)).unwrap();
+	nodes[0].messenger.send_onion_message(path, test_msg.clone(), Some(reply_path)).unwrap();
 	nodes[3].custom_message_handler.expect_message(TestCustomMessage::Request);
 	pass_along_path(&nodes);
 	// Make sure the last node successfully decoded the reply path.
@@ -358,7 +358,7 @@ fn reply_path() {
 	};
 	let reply_path = BlindedPath::new_for_message(&[nodes[2].get_node_pk(), nodes[1].get_node_pk(), nodes[0].get_node_pk()], &*nodes[0].keys_manager, &secp_ctx).unwrap();
 
-	nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg), Some(reply_path)).unwrap();
+	nodes[0].messenger.send_onion_message(path, test_msg, Some(reply_path)).unwrap();
 	nodes[3].custom_message_handler.expect_message(TestCustomMessage::Request);
 	pass_along_path(&nodes);
 
@@ -373,7 +373,7 @@ fn invalid_custom_message_type() {
 	let nodes = create_nodes(2);
 
 	struct InvalidCustomMessage{}
-	impl CustomOnionMessageContents for InvalidCustomMessage {
+	impl OnionMessageContents for InvalidCustomMessage {
 		fn tlv_type(&self) -> u64 {
 			// Onion message contents must have a TLV >= 64.
 			63
@@ -384,7 +384,7 @@ fn invalid_custom_message_type() {
 		fn write<W: Writer>(&self, _w: &mut W) -> Result<(), io::Error> { unreachable!() }
 	}
 
-	let test_msg = ParsedOnionMessageContents::Custom(InvalidCustomMessage {});
+	let test_msg = InvalidCustomMessage {};
 	let path = OnionMessagePath {
 		intermediate_nodes: vec![],
 		destination: Destination::Node(nodes[1].get_node_pk()),
@@ -402,9 +402,9 @@ fn peer_buffer_full() {
 		destination: Destination::Node(nodes[1].get_node_pk()),
 	};
 	for _ in 0..188 { // Based on MAX_PER_PEER_BUFFER_SIZE in OnionMessenger
-		nodes[0].messenger.send_onion_message(path.clone(), ParsedOnionMessageContents::Custom(test_msg.clone()), None).unwrap();
+		nodes[0].messenger.send_onion_message(path.clone(), test_msg.clone(), None).unwrap();
 	}
-	let err = nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg), None).unwrap_err();
+	let err = nodes[0].messenger.send_onion_message(path, test_msg, None).unwrap_err();
 	assert_eq!(err, SendError::BufferFull);
 }
 
@@ -425,7 +425,7 @@ fn many_hops() {
 		intermediate_nodes,
 		destination: Destination::Node(nodes[num_nodes-1].get_node_pk()),
 	};
-	nodes[0].messenger.send_onion_message(path, ParsedOnionMessageContents::Custom(test_msg), None).unwrap();
+	nodes[0].messenger.send_onion_message(path, test_msg, None).unwrap();
 	nodes[num_nodes-1].custom_message_handler.expect_message(TestCustomMessage::Response);
 	pass_along_path(&nodes);
 }

lightning/src/onion_message/messenger.rs

@@ -23,7 +23,8 @@ use crate::ln::features::{InitFeatures, NodeFeatures};
 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler};
 use crate::ln::onion_utils;
 use crate::ln::peer_handler::IgnoringMessageHandler;
-pub use super::packet::{CustomOnionMessageContents, ParsedOnionMessageContents};
+pub 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};
 use crate::util::logger::Logger;
@@ -60,7 +61,7 @@ use crate::prelude::*;
 /// # use lightning::blinded_path::BlindedPath;
 /// # use lightning::sign::KeysManager;
 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
-/// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, ParsedOnionMessageContents, OnionMessagePath, OnionMessenger};
+/// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
 /// # use lightning::util::logger::{Logger, Record};
 /// # use lightning::util::ser::{Writeable, Writer};
 /// # use lightning::io;
@@ -101,7 +102,7 @@ use crate::prelude::*;
 /// 		// Write your custom onion message to `w`
 /// 	}
 /// }
-/// impl CustomOnionMessageContents for YourCustomMessage {
+/// impl OnionMessageContents for YourCustomMessage {
 /// 	fn tlv_type(&self) -> u64 {
 /// 		# let your_custom_message_type = 42;
 /// 		your_custom_message_type
@@ -113,8 +114,7 @@ use crate::prelude::*;
 /// 	destination: Destination::Node(destination_node_id),
 /// };
 /// let reply_path = None;
-/// # let your_custom_message = YourCustomMessage {};
+/// # let message = YourCustomMessage {};
-/// let message = ParsedOnionMessageContents::Custom(your_custom_message);
 /// onion_messenger.send_onion_message(path, message, reply_path);
 ///
 /// // Create a blinded path to yourself, for someone to send an onion message to.
@@ -128,8 +128,7 @@ use crate::prelude::*;
 /// 	destination: Destination::BlindedPath(blinded_path),
 /// };
 /// let reply_path = None;
-/// # let your_custom_message = YourCustomMessage {};
+/// # let message = YourCustomMessage {};
-/// let message = ParsedOnionMessageContents::Custom(your_custom_message);
 /// onion_messenger.send_onion_message(path, message, reply_path);
 /// ```
 ///
@@ -244,7 +243,7 @@ pub enum SendError {
 pub trait CustomOnionMessageHandler {
 	/// The message known to the handler. To support multiple message types, you may want to make this
 	/// an enum with a variant for each supported message.
-	type CustomMessage: CustomOnionMessageContents;
+	type CustomMessage: OnionMessageContents;
 
 	/// Called with the custom message that was received, returning a response to send, if any.
 	fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
@@ -256,21 +255,20 @@ pub trait CustomOnionMessageHandler {
 
 /// A processed incoming onion message, containing either a Forward (another onion message)
 /// or a Receive payload with decrypted contents.
-pub enum PeeledOnion<CM: CustomOnionMessageContents> {
+pub enum PeeledOnion<T: OnionMessageContents> {
 	/// Forwarded onion, with the next node id and a new onion
 	Forward(PublicKey, OnionMessage),
 	/// Received onion message, with decrypted contents, path_id, and reply path
-	Receive(ParsedOnionMessageContents<CM>, Option<[u8; 32]>, Option<BlindedPath>)
+	Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 }
 
 /// 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.
-pub fn create_onion_message<ES: Deref, NS: Deref, T: CustomOnionMessageContents>(
+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: ParsedOnionMessageContents<T>,
+	path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
-	reply_path: Option<BlindedPath>,
 ) -> Result<(PublicKey, OnionMessage), SendError>
 where
 	ES::Target: EntropySource,
@@ -361,7 +359,7 @@ where
 		onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 		(control_tlvs_ss, custom_handler.deref(), logger.deref())
 	) {
-		Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
+		Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 			message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 		}, None)) => {
 			Ok(PeeledOnion::Receive(message, path_id, reply_path))
@@ -452,9 +450,8 @@ where
 	/// `path`.
 	///
 	/// See [`OnionMessenger`] for example usage.
-	pub fn send_onion_message<T: CustomOnionMessageContents>(
+	pub fn send_onion_message<T: OnionMessageContents>(
-		&self, path: OnionMessagePath, contents: ParsedOnionMessageContents<T>,
+		&self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
-		reply_path: Option<BlindedPath>
 	) -> Result<(), SendError> {
 		let (first_node_id, onion_msg) = create_onion_message(
 			&self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
@@ -471,9 +468,25 @@ where
 		}
 	}
 
-	fn find_path_and_enqueue_onion_message<T: CustomOnionMessageContents>(
+	fn handle_onion_message_response<T: OnionMessageContents>(
-		&self, contents: ParsedOnionMessageContents<T>, destination: Destination,
+		&self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
-		log_suffix: fmt::Arguments
+	) {
+		if let Some(response) = response {
+			match reply_path {
+				Some(reply_path) => {
+					self.find_path_and_enqueue_onion_message(
+						response, Destination::BlindedPath(reply_path), log_suffix
+					);
+				},
+				None => {
+					log_trace!(self.logger, "Missing reply path {}", log_suffix);
+				},
+			}
+		}
+	}
+
+	fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
+		&self, contents: T, destination: Destination, log_suffix: fmt::Arguments
 	) {
 		let sender = match self.node_signer.get_node_id(Recipient::Node) {
 			Ok(node_id) => node_id,
@@ -557,34 +570,27 @@ where
 				log_trace!(self.logger,
 					"Received an onion message with path_id {:02x?} and {} reply_path",
 						path_id, if reply_path.is_some() { "a" } else { "no" });
-				let response = match message {
+
+				match message {
 					ParsedOnionMessageContents::Offers(msg) => {
-						self.offers_handler.handle_message(msg)
+						let response = self.offers_handler.handle_message(msg);
-							.map(|msg| ParsedOnionMessageContents::Offers(msg))
+						self.handle_onion_message_response(
-					},
+							response, reply_path, format_args!(
-					ParsedOnionMessageContents::Custom(msg) => {
+								"when responding to Offers onion message with path_id {:02x?}",
-						self.custom_handler.handle_custom_message(msg)
+								path_id
-							.map(|msg| ParsedOnionMessageContents::Custom(msg))
-					},
-				};
-				if let Some(response) = response {
-					match reply_path {
-						Some(reply_path) => {
-							self.find_path_and_enqueue_onion_message(
-								response, Destination::BlindedPath(reply_path), format_args!(
-									"when responding to onion message with path_id {:02x?}", path_id
 							)
 						);
 					},
-						None => {
+					ParsedOnionMessageContents::Custom(msg) => {
-							log_trace!(
+						let response = self.custom_handler.handle_custom_message(msg);
-								self.logger,
+						self.handle_onion_message_response(
-								"Missing reply path when responding to onion message with path_id {:02x?}",
+							response, reply_path, format_args!(
+								"when responding to Custom onion message with path_id {:02x?}",
 								path_id
+							)
 						);
 					},
 				}
-				}
 			},
 			Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 				let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
@@ -683,9 +689,9 @@ pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
 
 /// Construct onion packet payloads and keys for sending an onion message along the given
 /// `unblinded_path` to the given `destination`.
-fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
+fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
-	secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
+	secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
-	message: ParsedOnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
+	mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 	let num_hops = unblinded_path.len() + destination.num_hops();
 	let mut payloads = Vec::with_capacity(num_hops);
@@ -761,7 +767,7 @@ fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing
 }
 
 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
-fn construct_onion_message_packet<T: CustomOnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
+fn construct_onion_message_packet<T: OnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
 	// Spec rationale:
 	// "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 	// onion, but this should be used sparingly as it is reduces anonymity set, hence the

lightning/src/onion_message/mod.rs

@@ -27,7 +27,7 @@ mod packet;
 mod functional_tests;
 
 // Re-export structs so they can be imported with just the `onion_message::` module prefix.
-pub use self::messenger::{CustomOnionMessageContents, CustomOnionMessageHandler, DefaultMessageRouter, Destination, MessageRouter, ParsedOnionMessageContents, OnionMessagePath, OnionMessenger, PeeledOnion, SendError, SimpleArcOnionMessenger, SimpleRefOnionMessenger};
+pub use self::messenger::{CustomOnionMessageHandler, DefaultMessageRouter, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger, PeeledOnion, SendError, SimpleArcOnionMessenger, SimpleRefOnionMessenger};
 pub use self::offers::{OffersMessage, OffersMessageHandler};
-pub use self::packet::Packet;
+pub use self::packet::{Packet, ParsedOnionMessageContents};
 pub(crate) use self::packet::ControlTlvs;

lightning/src/onion_message/offers.rs

@@ -16,6 +16,7 @@ use crate::offers::invoice_error::InvoiceError;
 use crate::offers::invoice_request::InvoiceRequest;
 use crate::offers::invoice::Bolt12Invoice;
 use crate::offers::parse::Bolt12ParseError;
+use crate::onion_message::OnionMessageContents;
 use crate::util::logger::Logger;
 use crate::util::ser::{Readable, ReadableArgs, Writeable, Writer};
 
@@ -63,15 +64,6 @@ impl OffersMessage {
 		}
 	}
 
-	/// The TLV record type for the message as used in an `onionmsg_tlv` TLV stream.
-	pub fn tlv_type(&self) -> u64 {
-		match self {
-			OffersMessage::InvoiceRequest(_) => INVOICE_REQUEST_TLV_TYPE,
-			OffersMessage::Invoice(_) => INVOICE_TLV_TYPE,
-			OffersMessage::InvoiceError(_) => INVOICE_ERROR_TLV_TYPE,
-		}
-	}
-
 	fn parse(tlv_type: u64, bytes: Vec<u8>) -> Result<Self, Bolt12ParseError> {
 		match tlv_type {
 			INVOICE_REQUEST_TLV_TYPE => Ok(Self::InvoiceRequest(InvoiceRequest::try_from(bytes)?)),
@@ -81,6 +73,16 @@ impl OffersMessage {
 	}
 }
 
+impl OnionMessageContents for OffersMessage {
+	fn tlv_type(&self) -> u64 {
+		match self {
+			OffersMessage::InvoiceRequest(_) => INVOICE_REQUEST_TLV_TYPE,
+			OffersMessage::Invoice(_) => INVOICE_TLV_TYPE,
+			OffersMessage::InvoiceError(_) => INVOICE_ERROR_TLV_TYPE,
+		}
+	}
+}
+
 impl Writeable for OffersMessage {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 		match self {

lightning/src/onion_message/packet.rs

@@ -103,31 +103,33 @@ impl LengthReadable for Packet {
 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
 /// message content itself, such as an invoice request.
-pub(super) enum Payload<T: CustomOnionMessageContents> {
+pub(super) enum Payload<T: OnionMessageContents> {
 	/// This payload is for an intermediate hop.
 	Forward(ForwardControlTlvs),
 	/// This payload is for the final hop.
 	Receive {
 		control_tlvs: ReceiveControlTlvs,
 		reply_path: Option<BlindedPath>,
-		message: ParsedOnionMessageContents<T>,
+		message: T,
 	}
 }
 
-/// The contents of an onion message as read from the wire.
+/// The contents of an [`OnionMessage`] as read from the wire.
+///
+/// [`OnionMessage`]: crate::ln::msgs::OnionMessage
 #[derive(Debug)]
-pub enum ParsedOnionMessageContents<T: CustomOnionMessageContents> {
+pub enum ParsedOnionMessageContents<T: OnionMessageContents> {
 	/// A message related to BOLT 12 Offers.
 	Offers(OffersMessage),
 	/// A custom onion message specified by the user.
 	Custom(T),
 }
 
-impl<T: CustomOnionMessageContents> ParsedOnionMessageContents<T> {
+impl<T: OnionMessageContents> OnionMessageContents for ParsedOnionMessageContents<T> {
 	/// Returns the type that was used to decode the message payload.
 	///
 	/// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
-	pub fn tlv_type(&self) -> u64 {
+	fn tlv_type(&self) -> u64 {
 		match self {
 			&ParsedOnionMessageContents::Offers(ref msg) => msg.tlv_type(),
 			&ParsedOnionMessageContents::Custom(ref msg) => msg.tlv_type(),
@@ -136,7 +138,7 @@ impl<T: CustomOnionMessageContents> ParsedOnionMessageContents<T> {
 }
 
 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
-impl<T: CustomOnionMessageContents> Writeable for ParsedOnionMessageContents<T> {
+impl<T: OnionMessageContents> Writeable for ParsedOnionMessageContents<T> {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 		match self {
 			ParsedOnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
@@ -145,8 +147,8 @@ impl<T: CustomOnionMessageContents> Writeable for ParsedOnionMessageContents<T>
 	}
 }
 
-/// The contents of a custom onion message.
+/// The contents of an onion message.
-pub trait CustomOnionMessageContents: Writeable {
+pub trait OnionMessageContents: Writeable {
 	/// Returns the TLV type identifying the message contents. MUST be >= 64.
 	fn tlv_type(&self) -> u64;
 }
@@ -172,7 +174,7 @@ pub(super) enum ReceiveControlTlvs {
 }
 
 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
-impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
+impl<T: OnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 		match &self.0 {
 			Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
@@ -211,8 +213,8 @@ impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
 }
 
 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
-impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized>
+impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized> ReadableArgs<(SharedSecret, &H, &L)>
-ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
+for Payload<ParsedOnionMessageContents<<H as CustomOnionMessageHandler>::CustomMessage>> {
 	fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
 		let (encrypted_tlvs_ss, handler, logger) = args;