Call all of BaseMessageHandler's methods on the send-only handler

In 9db37f2 we introduced a
`send_only_message_handler` which was intended to be used to send
messages to peers.

However, when we did so we forgot to add calls to its
`peer_connected`, `peer_disconnected`, `provided_node_features`,
and `provided_init_features` methods.

Here we add those methods, updating the comment somewhat to avoid
implying that they won't be called.

Author: TheBlueMatt

lightning/src/ln/peer_handler.rs

@@ -571,7 +571,7 @@ where
 	/// [`IgnoringMessageHandler`].
 	pub custom_message_handler: CustomM,
 
-	/// A message handler which only allows sending messages. This should generally be a
+	/// A message handler which can be used to send messages. This should generally be a
 	/// [`ChainMonitor`].
 	///
 	/// [`ChainMonitor`]: crate::chain::chainmonitor::ChainMonitor
@@ -1363,6 +1363,7 @@ where
 			| 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.custom_message_handler.provided_init_features(their_node_id)
+			| self.message_handler.send_only_message_handler.provided_init_features(their_node_id)
 	}
 
 	/// Indicates a new outbound connection has been established to a node with the given `node_id`
@@ -2157,6 +2158,19 @@ where
 				self.message_handler.onion_message_handler.peer_disconnected(their_node_id);
 				return Err(PeerHandleError {}.into());
 			}
+			let sends_handler = &self.message_handler.send_only_message_handler;
+			if let Err(()) = sends_handler.peer_connected(their_node_id, &msg, inbound) {
+				log_debug!(
+					logger,
+					"Sending-Only Message Handler decided we couldn't communicate with peer {}",
+					log_pubkey!(their_node_id)
+				);
+				self.message_handler.route_handler.peer_disconnected(their_node_id);
+				self.message_handler.chan_handler.peer_disconnected(their_node_id);
+				self.message_handler.onion_message_handler.peer_disconnected(their_node_id);
+				self.message_handler.custom_message_handler.peer_disconnected(their_node_id);
+				return Err(PeerHandleError {}.into());
+			}
 
 			peer_lock.awaiting_pong_timer_tick_intervals = 0;
 			peer_lock.their_features = Some(msg.features);
@@ -3362,6 +3376,7 @@ where
 			self.message_handler.chan_handler.peer_disconnected(node_id);
 			self.message_handler.onion_message_handler.peer_disconnected(node_id);
 			self.message_handler.custom_message_handler.peer_disconnected(node_id);
+			self.message_handler.send_only_message_handler.peer_disconnected(node_id);
 		}
 		descriptor.disconnect_socket();
 	}
@@ -3394,6 +3409,7 @@ where
 					self.message_handler.chan_handler.peer_disconnected(node_id);
 					self.message_handler.onion_message_handler.peer_disconnected(node_id);
 					self.message_handler.custom_message_handler.peer_disconnected(node_id);
+					self.message_handler.send_only_message_handler.peer_disconnected(node_id);
 				}
 			},
 		};
@@ -3579,7 +3595,8 @@ where
 		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.custom_message_handler.provided_node_features();
+			| self.message_handler.custom_message_handler.provided_node_features()
+			| self.message_handler.send_only_message_handler.provided_node_features();
 		let announcement = msgs::UnsignedNodeAnnouncement {
 			features,
 			timestamp: self.last_node_announcement_serial.fetch_add(1, Ordering::AcqRel),