Provide features in CustomMessageHandler

CustomMessageHandler implementations may need to advertise support for
features. Add methods to CustomMessageHandler to provide these and
combine them with features from other message handlers.

Author: jkczyz

lightning-custom-message/src/lib.rs

@@ -20,6 +20,7 @@
 //! # use bitcoin::secp256k1::PublicKey;
 //! # use lightning::io;
 //! # use lightning::ln::msgs::{DecodeError, LightningError};
+//! # use lightning::ln::features::{InitFeatures, NodeFeatures};
 //! use lightning::ln::peer_handler::CustomMessageHandler;
 //! use lightning::ln::wire::{CustomMessageReader, self};
 //! use lightning::util::ser::Writeable;
@@ -66,6 +67,12 @@
 //! #     fn get_and_clear_pending_msg(&self) -> Vec<(PublicKey, Self::CustomMessage)> {
 //! #         unimplemented!()
 //! #     }
+//! #     fn provided_node_features(&self) -> NodeFeatures {
+//! #         unimplemented!()
+//! #     }
+//! #     fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
+//! #         unimplemented!()
+//! #     }
 //! }
 //!
 //! #[derive(Debug)]
@@ -106,6 +113,12 @@
 //! #     fn get_and_clear_pending_msg(&self) -> Vec<(PublicKey, Self::CustomMessage)> {
 //! #         unimplemented!()
 //! #     }
+//! #     fn provided_node_features(&self) -> NodeFeatures {
+//! #         unimplemented!()
+//! #     }
+//! #     fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
+//! #         unimplemented!()
+//! #     }
 //! }
 //!
 //! #[derive(Debug)]
@@ -146,6 +159,12 @@
 //! #     fn get_and_clear_pending_msg(&self) -> Vec<(PublicKey, Self::CustomMessage)> {
 //! #         unimplemented!()
 //! #     }
+//! #     fn provided_node_features(&self) -> NodeFeatures {
+//! #         unimplemented!()
+//! #     }
+//! #     fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
+//! #         unimplemented!()
+//! #     }
 //! }
 //!
 //! # fn main() {
@@ -268,6 +287,22 @@ macro_rules! composite_custom_message_handler {
 					)*
 					.collect()
 			}
+
+			fn provided_node_features(&self) -> $crate::lightning::ln::features::NodeFeatures {
+				$crate::lightning::ln::features::NodeFeatures::empty()
+					$(
+						| self.$field.provided_node_features()
+					)*
+			}
+
+			fn provided_init_features(
+				&self, their_node_id: &$crate::bitcoin::secp256k1::PublicKey
+			) -> $crate::lightning::ln::features::InitFeatures {
+				$crate::lightning::ln::features::InitFeatures::empty()
+					$(
+						| self.$field.provided_init_features(their_node_id)
+					)*
+			}
 		}
 
 		impl $crate::lightning::ln::wire::CustomMessageReader for $handler {

lightning/src/ln/peer_handler.rs

@@ -64,6 +64,20 @@ pub trait CustomMessageHandler: wire::CustomMessageReader {
 	/// in the process. Each message is paired with the node id of the intended recipient. If no
 	/// connection to the node exists, then the message is simply not sent.
 	fn get_and_clear_pending_msg(&self) -> Vec<(PublicKey, Self::CustomMessage)>;
+
+	/// 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`]
+	/// which are broadcasted in our [`NodeAnnouncement`] message.
+	///
+	/// [`NodeAnnouncement`]: crate::ln::msgs::NodeAnnouncement
+	fn provided_node_features(&self) -> NodeFeatures;
+
+	/// Gets the init feature flags which should be sent to the given peer. All available handlers
+	/// are queried similarly and their feature flags are OR'd together to form the [`InitFeatures`]
+	/// which are sent in our [`Init`] message.
+	///
+	/// [`Init`]: crate::ln::msgs::Init
+	fn provided_init_features(&self, their_node_id: &PublicKey) -> InitFeatures;
 }
 
 /// A dummy struct which implements `RoutingMessageHandler` without storing any routing information
@@ -149,6 +163,12 @@ impl CustomMessageHandler for IgnoringMessageHandler {
 	}
 
 	fn get_and_clear_pending_msg(&self) -> Vec<(PublicKey, Self::CustomMessage)> { Vec::new() }
+
+	fn provided_node_features(&self) -> NodeFeatures { NodeFeatures::empty() }
+
+	fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
+		InitFeatures::empty()
+	}
 }
 
 /// A dummy struct which implements `ChannelMessageHandler` without having any channels.
@@ -1192,7 +1212,8 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 								insert_node_id!();
 								let features = self.message_handler.chan_handler.provided_init_features(&their_node_id)
 									| self.message_handler.route_handler.provided_init_features(&their_node_id)
-									| self.message_handler.onion_message_handler.provided_init_features(&their_node_id);
+									| self.message_handler.onion_message_handler.provided_init_features(&their_node_id)
+									| self.custom_message_handler.provided_init_features(&their_node_id);
 								let resp = msgs::Init { features, remote_network_address: filter_addresses(peer.their_net_address.clone()) };
 								self.enqueue_message(peer, &resp);
 								peer.awaiting_pong_timer_tick_intervals = 0;
@@ -1206,7 +1227,8 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 								insert_node_id!();
 								let features = self.message_handler.chan_handler.provided_init_features(&their_node_id)
 									| self.message_handler.route_handler.provided_init_features(&their_node_id)
-									| self.message_handler.onion_message_handler.provided_init_features(&their_node_id);
+									| self.message_handler.onion_message_handler.provided_init_features(&their_node_id)
+									| self.custom_message_handler.provided_init_features(&their_node_id);
 								let resp = msgs::Init { features, remote_network_address: filter_addresses(peer.their_net_address.clone()) };
 								self.enqueue_message(peer, &resp);
 								peer.awaiting_pong_timer_tick_intervals = 0;
@@ -2148,7 +2170,8 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 
 		let features = self.message_handler.chan_handler.provided_node_features()
 			| self.message_handler.route_handler.provided_node_features()
-			| self.message_handler.onion_message_handler.provided_node_features();
+			| self.message_handler.onion_message_handler.provided_node_features()
+			| self.custom_message_handler.provided_node_features();
 		let announcement = msgs::UnsignedNodeAnnouncement {
 			features,
 			timestamp: self.last_node_announcement_serial.fetch_add(1, Ordering::AcqRel),