Time out AwatingRemoteRAA outgoing HTLCs when we reach cltv_expiry

In case of committing out-of-time outgoing HTLCs, we force
ourselves to close the channel to avoid remote peer claims on a
non-backed HTLC

Author: Antoine Riard

lightning/src/ln/channel.rs

@@ -2961,12 +2961,24 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	}
 
 	/// Called by channelmanager based on chain blocks being connected.
-	/// Note that we only need to use this to detect funding_signed, anything else is handled by
-	/// the channel_monitor.
+	/// We need to use this to detect funding_signed and outgoing HTLC timed out before we were able 
+	/// to commit them on remote commitment tx, anything else is handled by the channel_monitor.
 	/// In case of Err, the channel may have been closed, at which point the standard requirements
 	/// apply - no calls may be made except those explicitly stated to be allowed post-shutdown.
 	/// Only returns an ErrorAction of DisconnectPeer, if Err.
-	pub fn block_connected(&mut self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> Result<Option<msgs::FundingLocked>, msgs::ErrorMessage> {
+	pub fn block_connected(&mut self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash, u64)>), msgs::ErrorMessage> {
+		let mut timed_out_htlcs = Vec::new();
+		self.holding_cell_htlc_updates.retain(|htlc_update| {
+			match htlc_update {
+				&HTLCUpdateAwaitingACK::AddHTLC { ref payment_hash, ref source, ref cltv_expiry, ref amount_msat, .. } => {
+					if cltv_expiry <= &height { // XXX follow 0a4821b
+						timed_out_htlcs.push((source.clone(), payment_hash.clone(), *amount_msat));
+						false
+					} else { true }
+				},
+				_ => true
+			}
+		});
 		let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
 		if header.bitcoin_hash() != self.last_block_connected {
 			self.last_block_connected = header.bitcoin_hash();
@@ -3002,13 +3014,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 						if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) == 0 {
 							let next_per_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
 							let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &next_per_commitment_secret);
-							return Ok(Some(msgs::FundingLocked {
+							return Ok((Some(msgs::FundingLocked {
 								channel_id: self.channel_id,
 								next_per_commitment_point: next_per_commitment_point,
-							}));
+							}), timed_out_htlcs));
 						} else {
 							self.monitor_pending_funding_locked = true;
-							return Ok(None);
+							return Ok((None, timed_out_htlcs));
 						}
 					}
 				}
@@ -3054,7 +3066,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				}
 			}
 		}
-		Ok(None)
+		Ok((None, timed_out_htlcs))
 	}
 
 	/// Called by channelmanager based on chain blocks being disconnected.

lightning/src/ln/channelmanager.rs

@@ -2821,20 +2821,26 @@ impl<ChanSigner: ChannelKeys> ChainListener for ChannelManager<ChanSigner> {
 			let short_to_id = channel_state.short_to_id;
 			let pending_msg_events = channel_state.pending_msg_events;
 			channel_state.by_id.retain(|_, channel| {
-				let chan_res = channel.block_connected(header, height, txn_matched, indexes_of_txn_matched);
-				if let Ok(Some(funding_locked)) = chan_res {
-					pending_msg_events.push(events::MessageSendEvent::SendFundingLocked {
-						node_id: channel.get_their_node_id(),
-						msg: funding_locked,
-					});
-					if let Some(announcement_sigs) = self.get_announcement_sigs(channel) {
-						pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
+				let res = channel.block_connected(header, height, txn_matched, indexes_of_txn_matched);
+				if let Ok((chan_res, mut timed_out_pending_htlcs)) = res {
+					timed_out_htlcs.reserve(timed_out_pending_htlcs.len());
+					for (htlc_src, payment_hash, value) in timed_out_pending_htlcs.drain(..) {
+						timed_out_htlcs.push((htlc_src, payment_hash, value));
+					}
+					if let Some(funding_locked) = chan_res {
+						pending_msg_events.push(events::MessageSendEvent::SendFundingLocked {
 							node_id: channel.get_their_node_id(),
-							msg: announcement_sigs,
+							msg: funding_locked,
 						});
+						if let Some(announcement_sigs) = self.get_announcement_sigs(channel) {
+							pending_msg_events.push(events::MessageSendEvent::SendAnnouncementSignatures {
+								node_id: channel.get_their_node_id(),
+								msg: announcement_sigs,
+							});
+						}
+						short_to_id.insert(channel.get_short_channel_id().unwrap(), channel.channel_id());
 					}
-					short_to_id.insert(channel.get_short_channel_id().unwrap(), channel.channel_id());
-				} else if let Err(e) = chan_res {
+				} else if let Err(e) = res {
 					pending_msg_events.push(events::MessageSendEvent::HandleError {
 						node_id: channel.get_their_node_id(),
 						action: msgs::ErrorAction::SendErrorMessage { msg: e },