OR InitFeatures and NodeFeatures from onion message handler

Similar to how we OR our InitFeaures and NodeFeatures across both our channel
and routing message handlers, we also want to OR the features of our onion
message handler.

lightning/src/ln/msgs.rs

@@ -980,6 +980,19 @@ pub trait OnionMessageHandler : OnionMessageProvider {
 	/// Indicates a connection to the peer failed/an existing connection was lost. Allows handlers to
 	/// drop and refuse to forward onion messages to this peer.
 	fn peer_disconnected(&self, their_node_id: &PublicKey, no_connection_possible: bool);
+
+	// 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`]
+	/// which are broadcasted in our [`NodeAnnouncement`] message.
+	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.
+	///
+	/// Note that this method is called before [`Self::peer_connected`].
+	fn provided_init_features(&self, their_node_id: &PublicKey) -> InitFeatures;
 }
 
 mod fuzzy_internal_msgs {

lightning/src/ln/peer_handler.rs

@@ -89,6 +89,10 @@ impl OnionMessageHandler for IgnoringMessageHandler {
 	fn handle_onion_message(&self, _their_node_id: &PublicKey, _msg: &msgs::OnionMessage) {}
 	fn peer_connected(&self, _their_node_id: &PublicKey, _init: &msgs::Init) {}
 	fn peer_disconnected(&self, _their_node_id: &PublicKey, _no_connection_possible: bool) {}
+	fn provided_node_features(&self) -> NodeFeatures { NodeFeatures::empty() }
+	fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
+		InitFeatures::empty()
+	}
 }
 impl Deref for IgnoringMessageHandler {
 	type Target = IgnoringMessageHandler;
@@ -1062,7 +1066,8 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 								peer.their_node_id = Some(their_node_id);
 								insert_node_id!();
 								let features = self.message_handler.chan_handler.provided_init_features(&their_node_id)
-									.or(self.message_handler.route_handler.provided_init_features(&their_node_id));
+									.or(self.message_handler.route_handler.provided_init_features(&their_node_id))
+									.or(self.message_handler.onion_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;
@@ -1075,7 +1080,8 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 								peer.their_node_id = Some(their_node_id);
 								insert_node_id!();
 								let features = self.message_handler.chan_handler.provided_init_features(&their_node_id)
-									.or(self.message_handler.route_handler.provided_init_features(&their_node_id));
+									.or(self.message_handler.route_handler.provided_init_features(&their_node_id))
+									.or(self.message_handler.onion_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;
@@ -1971,7 +1977,8 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 		addresses.sort_by_key(|addr| addr.get_id());
 
 		let features = self.message_handler.chan_handler.provided_node_features()
-			.or(self.message_handler.route_handler.provided_node_features());
+			.or(self.message_handler.route_handler.provided_node_features())
+			.or(self.message_handler.onion_message_handler.provided_node_features());
 		let announcement = msgs::UnsignedNodeAnnouncement {
 			features,
 			timestamp: self.last_node_announcement_serial.fetch_add(1, Ordering::AcqRel) as u32,

lightning/src/onion_message/messenger.rs

@@ -16,6 +16,7 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
 
 use chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Recipient, Sign};
+use ln::features::{InitFeatures, NodeFeatures};
 use ln::msgs::{self, OnionMessageHandler};
 use ln::onion_utils;
 use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
@@ -345,6 +346,18 @@ impl<Signer: Sign, K: Deref, L: Deref> OnionMessageHandler for OnionMessenger<Si
 		let mut pending_msgs = self.pending_messages.lock().unwrap();
 		pending_msgs.remove(their_node_id);
 	}
+
+	fn provided_node_features(&self) -> NodeFeatures {
+		let mut features = NodeFeatures::empty();
+		features.set_onion_messages_optional();
+		features
+	}
+
+	fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
+		let mut features = InitFeatures::empty();
+		features.set_onion_messages_optional();
+		features
+	}
 }
 
 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageProvider for OnionMessenger<Signer, K, L>