Document our handling of announcement_sigs

We may have in the future to rebroadcast announcement_sigs at
peer reconnection if this a burning issue as spec lacks
a acknowledgement mechanism.

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index c863f46b613c77c27198d85e8f3121d9a2eb5c20..5452e365df087670ce14547b5a7250fd8dd87750 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -1972,6 +1972,15 @@ impl ChannelManager {
                                }
                                try_chan_entry!(self, chan.get_mut().funding_locked(&msg), channel_state, chan);
                                if let Some(announcement_sigs) = self.get_announcement_sigs(chan.get()) {
+                                       // If we see locking block before receiving remote funding_locked, we broadcast our
+                                       // announcement_sigs at remote funding_locked reception. If we receive remote
+                                       // funding_locked before seeing locking block, we broadcast our announcement_sigs at locking
+                                       // block connection. We should guanrantee to broadcast announcement_sigs to our peer whatever
+                                       // the order of the events but our peer may not receive it due to disconnection. The specs
+                                       // lacking an acknowledgement for announcement_sigs we may have to re-send them at peer
+                                       // connection in the future if simultaneous misses by both peers due to network/hardware
+                                       // failures is an issue. Note, to achieve its goal, only one of the announcement_sigs needs
+                                       // to be received, from then sigs are going to be flood to the whole network.
                                        channel_state.pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
                                                node_id: their_node_id.clone(),
                                                msg: announcement_sigs,