Send warning messages when repeating shutdown messages at volume

Author: TheBlueMatt

lightning/src/events/mod.rs

@@ -1501,6 +1501,7 @@ impl MaybeReadable for Event {
 /// broadcast to most peers).
 /// These events are handled by PeerManager::process_events if you are using a PeerManager.
 #[derive(Clone, Debug)]
+#[cfg_attr(test, derive(PartialEq))]
 pub enum MessageSendEvent {
 	/// Used to indicate that we've accepted a channel open and should send the accept_channel
 	/// message provided to the given peer.

lightning/src/ln/channelmanager.rs

@@ -7512,6 +7512,16 @@ where
 								msg,
 							});
 						}
+						peer_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
+							node_id: *counterparty_node_id,
+							action: msgs::ErrorAction::SendWarningMessage {
+								msg: msgs::WarningMessage {
+									channel_id: msg.channel_id,
+									data: "You appear to be exhibiting LND bug 6039, we'll keep sending you shutdown messages until you handle them correctly".to_owned()
+								},
+								log_level: Level::Trace,
+							}
+						});
 					}
 				}
 				return;

lightning/src/ln/msgs.rs

@@ -1144,7 +1144,7 @@ enum EncodingType {
 }
 
 /// Used to put an error message in a [`LightningError`].
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum ErrorAction {
 	/// The peer took some action which made us think they were useless. Disconnect them.
 	DisconnectPeer {

lightning/src/ln/shutdown_tests.rs

@@ -219,7 +219,13 @@ fn test_lnd_bug_6039() {
 	// see if LND will accept our protocol compliance.
 	let err_msg = msgs::ErrorMessage { channel_id: chan.2, data: "link failed to shutdown".to_string() };
 	nodes[0].node.handle_error(&nodes[1].node.get_our_node_id(), &err_msg);
-	let _node_0_repeated_shutdown = get_event_msg!(nodes[0], MessageSendEvent::SendShutdown, nodes[1].node.get_our_node_id());
+	let node_a_responses = nodes[0].node.get_and_clear_pending_msg_events();
+	assert_eq!(node_a_responses[0], MessageSendEvent::SendShutdown {
+			node_id: nodes[1].node.get_our_node_id(),
+			msg: node_0_shutdown,
+		});
+	if let MessageSendEvent::HandleError { action: msgs::ErrorAction::SendWarningMessage { .. }, .. }
+		= node_a_responses[1] {} else { panic!(); }
 
 	let node_1_shutdown = get_event_msg!(nodes[1], MessageSendEvent::SendShutdown, nodes[0].node.get_our_node_id());