From 2acebb9357386a9f6664a920612cfaa5a64135a4 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Thu, 14 Mar 2024 19:47:07 +0000 Subject: [PATCH] Avoid writing `ChannelManager` when hitting lnd bug 6039 When we hit lnd bug 6039, we end up sending error messages to peers in a loop. This should be fine, but because we used the generic `PersistenceNotifierGuard::notify_on_drop` lock above the specific handling, we end up writing `ChannelManager` every time we manage a round-trip to our peer. This can add up quite quickly, and isn't actually changing, so we really need to avoid writing the `ChannelManager` in this case. --- lightning/src/ln/channelmanager.rs | 55 +++++++++++++++++------------- 1 file changed, 32 insertions(+), 23 deletions(-) diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index a9aa1470..05810ab1 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -8178,8 +8178,6 @@ where } fn handle_error(&self, counterparty_node_id: &PublicKey, msg: &msgs::ErrorMessage) { - let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self); - match &msg.data as &str { "cannot co-op close channel w/ active htlcs"| "link failed to shutdown" => @@ -8192,34 +8190,45 @@ where // We're not going to bother handling this in a sensible way, instead simply // repeating the Shutdown message on repeat until morale improves. if !msg.channel_id.is_zero() { - let per_peer_state = self.per_peer_state.read().unwrap(); - let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id); - if peer_state_mutex_opt.is_none() { return; } - let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap(); - if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get(&msg.channel_id) { - if let Some(msg) = chan.get_outbound_shutdown() { - peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown { - node_id: *counterparty_node_id, - 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, + PersistenceNotifierGuard::optionally_notify( + self, + || -> NotifyOption { + let per_peer_state = self.per_peer_state.read().unwrap(); + let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id); + if peer_state_mutex_opt.is_none() { return NotifyOption::SkipPersistNoEvents; } + let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap(); + if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get(&msg.channel_id) { + if let Some(msg) = chan.get_outbound_shutdown() { + peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown { + node_id: *counterparty_node_id, + 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, + } + }); + // This can happen in a fairly tight loop, so we absolutely cannot trigger + // a `ChannelManager` write here. + return NotifyOption::SkipPersistHandleEvents; } - }); - } + NotifyOption::SkipPersistNoEvents + } + ); } return; } _ => {} } + let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self); + if msg.channel_id.is_zero() { let channel_ids: Vec = { let per_peer_state = self.per_peer_state.read().unwrap(); -- 2.30.2