Don't create chan-closed mon update for outbound never-signed chans

[rust-lightning] / lightning / src / ln / channel.rs

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index c34fc6a38c28e5ae89a5cd98e094ee7a5348781a..abf2834c26a93d6b020ea095959014c08c963642 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -4016,11 +4016,23 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                                _ => {}
                        }
                }
+               let funding_txo = if let Some(funding_txo) = self.funding_txo {
+                       // If we haven't yet exchanged funding signatures (ie channel_state < FundingSent),
+                       // returning a channel monitor update here would imply a channel monitor update before
+                       // we even registered the channel monitor to begin with, which is invalid.
+                       // Thus, if we aren't actually at a point where we could conceivably broadcast the
+                       // funding transaction, don't return a funding txo (which prevents providing the
+                       // monitor update to the user, even if we return one).
+                       // See test_duplicate_chan_id and test_pre_lockin_no_chan_closed_update for more.
+                       if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::ChannelFunded as u32 | ChannelState::ShutdownComplete as u32) != 0 {
+                               Some(funding_txo.clone())
+                       } else { None }
+               } else { None };
 
                self.channel_state = ChannelState::ShutdownComplete as u32;
                self.update_time_counter += 1;
                self.latest_monitor_update_id += 1;
-               (self.funding_txo.clone(), ChannelMonitorUpdate {
+               (funding_txo, ChannelMonitorUpdate {
                        update_id: self.latest_monitor_update_id,
                        updates: vec![ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast }],
                }, dropped_outbound_htlcs)