Re-broadcast our own gossip even if its same as the last broadcast

Even if our gossip hasn't changed, we should be willing to
re-broadcast it to our peers. All our peers may have been
disconnected the last time we broadcasted it.

Author: TheBlueMatt

lightning/src/ln/msgs.rs

@@ -715,6 +715,10 @@ pub enum ErrorAction {
 	/// The peer did something harmless that we weren't able to meaningfully process.
 	/// If the error is logged, log it at the given level.
 	IgnoreAndLog(logger::Level),
+	/// The peer provided us with a gossip message which we'd already seen. In most cases this
+	/// should be ignored, but it may result in the message being forwarded if it is a duplicate of
+	/// our own channel announcements.
+	IgnoreDuplicateGossip,
 	/// The peer did something incorrect. Tell them.
 	SendErrorMessage {
 		/// The message to send.

lightning/src/ln/peer_handler.rs

@@ -811,6 +811,7 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
 													log_given_level!(self.logger, level, "Error handling message{}; ignoring: {}", OptionalFromDebugger(&peer.their_node_id), e.err);
 													continue
 												},
+												msgs::ErrorAction::IgnoreDuplicateGossip => continue, // Don't even bother logging these
 												msgs::ErrorAction::IgnoreError => {
 													log_debug!(self.logger, "Error handling message{}; ignoring: {}", OptionalFromDebugger(&peer.their_node_id), e.err);
 													continue;
@@ -1351,23 +1352,31 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
 					},
 					MessageSendEvent::BroadcastChannelAnnouncement { msg, update_msg } => {
 						log_debug!(self.logger, "Handling BroadcastChannelAnnouncement event in peer_handler for short channel id {}", msg.contents.short_channel_id);
-						if self.message_handler.route_handler.handle_channel_announcement(&msg).is_ok() {
-							self.forward_broadcast_msg(peers, &wire::Message::ChannelAnnouncement(msg), None);
+						match self.message_handler.route_handler.handle_channel_announcement(&msg) {
+							Ok(_) | Err(LightningError { action: msgs::ErrorAction::IgnoreDuplicateGossip, .. }) =>
+								self.forward_broadcast_msg(peers, &wire::Message::ChannelAnnouncement(msg), None),
+							_ => {},
 						}
-						if self.message_handler.route_handler.handle_channel_update(&update_msg).is_ok() {
-							self.forward_broadcast_msg(peers, &wire::Message::ChannelUpdate(update_msg), None);
+						match self.message_handler.route_handler.handle_channel_update(&update_msg) {
+							Ok(_) | Err(LightningError { action: msgs::ErrorAction::IgnoreDuplicateGossip, .. }) =>
+								self.forward_broadcast_msg(peers, &wire::Message::ChannelUpdate(update_msg), None),
+							_ => {},
 						}
 					},
 					MessageSendEvent::BroadcastNodeAnnouncement { msg } => {
 						log_debug!(self.logger, "Handling BroadcastNodeAnnouncement event in peer_handler");
-						if self.message_handler.route_handler.handle_node_announcement(&msg).is_ok() {
-							self.forward_broadcast_msg(peers, &wire::Message::NodeAnnouncement(msg), None);
+						match self.message_handler.route_handler.handle_node_announcement(&msg) {
+							Ok(_) | Err(LightningError { action: msgs::ErrorAction::IgnoreDuplicateGossip, .. }) =>
+								self.forward_broadcast_msg(peers, &wire::Message::NodeAnnouncement(msg), None),
+							_ => {},
 						}
 					},
 					MessageSendEvent::BroadcastChannelUpdate { msg } => {
 						log_debug!(self.logger, "Handling BroadcastChannelUpdate event in peer_handler for short channel id {}", msg.contents.short_channel_id);
-						if self.message_handler.route_handler.handle_channel_update(&msg).is_ok() {
-							self.forward_broadcast_msg(peers, &wire::Message::ChannelUpdate(msg), None);
+						match self.message_handler.route_handler.handle_channel_update(&msg) {
+							Ok(_) | Err(LightningError { action: msgs::ErrorAction::IgnoreDuplicateGossip, .. }) =>
+								self.forward_broadcast_msg(peers, &wire::Message::ChannelUpdate(msg), None),
+							_ => {},
 						}
 					},
 					MessageSendEvent::SendChannelUpdate { ref node_id, ref msg } => {
@@ -1400,6 +1409,7 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
 							msgs::ErrorAction::IgnoreAndLog(level) => {
 								log_given_level!(self.logger, level, "Received a HandleError event to be ignored for node {}", log_pubkey!(node_id));
 							},
+							msgs::ErrorAction::IgnoreDuplicateGossip => {},
 							msgs::ErrorAction::IgnoreError => {
 								log_debug!(self.logger, "Received a HandleError event to be ignored for node {}", log_pubkey!(node_id));
 							},

lightning/src/routing/network_graph.rs

@@ -847,8 +847,10 @@ impl NetworkGraph {
 			None => Err(LightningError{err: "No existing channels for node_announcement".to_owned(), action: ErrorAction::IgnoreError}),
 			Some(node) => {
 				if let Some(node_info) = node.announcement_info.as_ref() {
-					if node_info.last_update  >= msg.timestamp {
+					if node_info.last_update  > msg.timestamp {
 						return Err(LightningError{err: "Update older than last processed update".to_owned(), action: ErrorAction::IgnoreAndLog(Level::Gossip)});
+					} else if node_info.last_update  == msg.timestamp {
+						return Err(LightningError{err: "Update had the same timestamp as last processed update".to_owned(), action: ErrorAction::IgnoreDuplicateGossip});
 					}
 				}
 
@@ -977,7 +979,7 @@ impl NetworkGraph {
 					Self::remove_channel_in_nodes(&mut nodes, &entry.get(), msg.short_channel_id);
 					*entry.get_mut() = chan_info;
 				} else {
-					return Err(LightningError{err: "Already have knowledge of channel".to_owned(), action: ErrorAction::IgnoreAndLog(Level::Gossip)})
+					return Err(LightningError{err: "Already have knowledge of channel".to_owned(), action: ErrorAction::IgnoreDuplicateGossip});
 				}
 			},
 			BtreeEntry::Vacant(entry) => {
@@ -1082,8 +1084,10 @@ impl NetworkGraph {
 				macro_rules! maybe_update_channel_info {
 					( $target: expr, $src_node: expr) => {
 						if let Some(existing_chan_info) = $target.as_ref() {
-							if existing_chan_info.last_update >= msg.timestamp {
+							if existing_chan_info.last_update > msg.timestamp {
 								return Err(LightningError{err: "Update older than last processed update".to_owned(), action: ErrorAction::IgnoreAndLog(Level::Gossip)});
+							} else if existing_chan_info.last_update == msg.timestamp {
+								return Err(LightningError{err: "Update had same timestamp as last processed update".to_owned(), action: ErrorAction::IgnoreDuplicateGossip});
 							}
 							chan_was_enabled = existing_chan_info.enabled;
 						} else {
@@ -1720,7 +1724,7 @@ mod tests {
 
 		match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
 			Ok(_) => panic!(),
-			Err(e) => assert_eq!(e.err, "Update older than last processed update")
+			Err(e) => assert_eq!(e.err, "Update had same timestamp as last processed update")
 		};
 		unsigned_channel_update.timestamp += 500;