From 1b3249a1929929170bba9d2553d7a9c8670193e5 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Thu, 22 Jul 2021 16:05:48 +0000
Subject: [PATCH] Handle sending and receiving warning messages

---
 lightning/src/ln/msgs.rs         | 11 ++++++++++-
 lightning/src/ln/peer_handler.rs | 26 ++++++++++++++++++++++++++
 lightning/src/ln/wire.rs         |  9 +++++++++
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/lightning/src/ln/msgs.rs b/lightning/src/ln/msgs.rs
index 1335a04c4..6c04636a4 100644
--- a/lightning/src/ln/msgs.rs
+++ b/lightning/src/ln/msgs.rs
@@ -731,7 +731,16 @@ pub enum ErrorAction {
 	/// The peer did something incorrect. Tell them.
 	SendErrorMessage {
 		/// The message to send.
-		msg: ErrorMessage
+		msg: ErrorMessage,
+	},
+	/// The peer did something incorrect. Tell them without closing any channels.
+	SendWarningMessage {
+		/// The message to send.
+		msg: WarningMessage,
+		/// The peer may have done something harmless that we weren't able to meaningfully process,
+		/// though we should still tell them about it.
+		/// If this event is logged, log it at the given level.
+		log_level: logger::Level,
 	},
 }
 
diff --git a/lightning/src/ln/peer_handler.rs b/lightning/src/ln/peer_handler.rs
index 9157dc87d..6607d986a 100644
--- a/lightning/src/ln/peer_handler.rs
+++ b/lightning/src/ln/peer_handler.rs
@@ -821,6 +821,11 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
 													self.enqueue_message(peer, &msg);
 													continue;
 												},
+												msgs::ErrorAction::SendWarningMessage { msg, log_level } => {
+													log_given_level!(self.logger, log_level, "Error handling message{}; sending warning message with: {}", OptionalFromDebugger(&peer.their_node_id), e.err);
+													self.enqueue_message(peer, &msg);
+													continue;
+												},
 											}
 										}
 									}
@@ -1022,6 +1027,21 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
 					return Err(PeerHandleError{ no_connection_possible: true }.into());
 				}
 			},
+			wire::Message::Warning(msg) => {
+				let mut data_is_printable = true;
+				for b in msg.data.bytes() {
+					if b < 32 || b > 126 {
+						data_is_printable = false;
+						break;
+					}
+				}
+
+				if data_is_printable {
+					log_debug!(self.logger, "Got warning message from {}: {}", log_pubkey!(peer.their_node_id.unwrap()), msg.data);
+				} else {
+					log_debug!(self.logger, "Got warning message from {} with non-ASCII error message", log_pubkey!(peer.their_node_id.unwrap()));
+				}
+			},
 
 			wire::Message::Ping(msg) => {
 				if msg.ponglen < 65532 {
@@ -1419,6 +1439,12 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
 										msg.data);
 								self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
 							},
+							msgs::ErrorAction::SendWarningMessage { ref msg, ref log_level } => {
+								log_given_level!(self.logger, *log_level, "Handling SendWarningMessage HandleError event in peer_handler for node {} with message {}",
+										log_pubkey!(node_id),
+										msg.data);
+								self.enqueue_message(get_peer_for_forwarding!(node_id), msg);
+							},
 						}
 					},
 					MessageSendEvent::SendChannelRangeQuery { ref node_id, ref msg } => {
diff --git a/lightning/src/ln/wire.rs b/lightning/src/ln/wire.rs
index d3cc257f5..2c77fd46b 100644
--- a/lightning/src/ln/wire.rs
+++ b/lightning/src/ln/wire.rs
@@ -35,6 +35,7 @@ pub trait CustomMessageReader {
 pub(crate) enum Message<T> where T: core::fmt::Debug + Type {
 	Init(msgs::Init),
 	Error(msgs::ErrorMessage),
+	Warning(msgs::WarningMessage),
 	Ping(msgs::Ping),
 	Pong(msgs::Pong),
 	OpenChannel(msgs::OpenChannel),
@@ -74,6 +75,7 @@ impl<T> Message<T> where T: core::fmt::Debug + Type {
 		match self {
 			&Message::Init(ref msg) => msg.type_id(),
 			&Message::Error(ref msg) => msg.type_id(),
+			&Message::Warning(ref msg) => msg.type_id(),
 			&Message::Ping(ref msg) => msg.type_id(),
 			&Message::Pong(ref msg) => msg.type_id(),
 			&Message::OpenChannel(ref msg) => msg.type_id(),
@@ -133,6 +135,9 @@ where
 		msgs::ErrorMessage::TYPE => {
 			Ok(Message::Error(Readable::read(buffer)?))
 		},
+		msgs::WarningMessage::TYPE => {
+			Ok(Message::Warning(Readable::read(buffer)?))
+		},
 		msgs::Ping::TYPE => {
 			Ok(Message::Ping(Readable::read(buffer)?))
 		},
@@ -264,6 +269,10 @@ impl Encode for msgs::ErrorMessage {
 	const TYPE: u16 = 17;
 }
 
+impl Encode for msgs::WarningMessage {
+	const TYPE: u16 = 1;
+}
+
 impl Encode for msgs::Ping {
 	const TYPE: u16 = 18;
 }
-- 
2.39.5