Fail HTLC backwards on unrevoked remote commitment tx broadcast

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

diff --git a/src/ln/channelmonitor.rs b/src/ln/channelmonitor.rs
index cdd0aad1139734ab29d5b8609b345f85214cccb2..13cdfd2fe5d75433c5c28db097af4c12c0965de1 100644 (file)
--- a/src/ln/channelmonitor.rs
+++ b/src/ln/channelmonitor.rs
@@ -1247,6 +1247,42 @@ impl ChannelMonitor {
 
                        log_trace!(self, "Got broadcast of non-revoked remote commitment transaction {}", commitment_txid);
 
+                       // TODO: We really should only fail backwards after our revocation claims have been
+                       // confirmed, but we also need to do more other tracking of in-flight pre-confirm
+                       // on-chain claims, so we can do that at the same time.
+                       macro_rules! check_htlc_fails {
+                               ($txid: expr, $commitment_tx: expr, $id: tt) => {
+                                       if let Some(&(_, ref latest_outpoints)) = self.remote_claimable_outpoints.get(&$txid) {
+                                               $id: for &(ref payment_hash, ref source, _) in latest_outpoints.iter() {
+                                                       // Check if the HTLC is present in the commitment transaction that was
+                                                       // broadcast, but not if it was below the dust limit, which we should
+                                                       // fail backwards immediately as there is no way for us to learn the
+                                                       // payment_preimage.
+                                                       // Note that if the dust limit were allowed to change between
+                                                       // commitment transactions we'd want to be check whether *any*
+                                                       // broadcastable commitment transaction has the HTLC in it, but it
+                                                       // cannot currently change after channel initialization, so we don't
+                                                       // need to here.
+                                                       for &(_, ref broadcast_source, ref output_idx) in per_commitment_data.1.iter() {
+                                                               if output_idx.is_some() && source == broadcast_source {
+                                                                       continue $id;
+                                                               }
+                                                       }
+                                                       log_trace!(self, "Failing HTLC with payment_hash {} from {} remote commitment tx due to broadcast of remote commitment transaction", log_bytes!(payment_hash.0), $commitment_tx);
+                                                       htlc_updated.push(((*source).clone(), None, payment_hash.clone()));
+                                               }
+                                       }
+                               }
+                       }
+                       if let Storage::Local { ref current_remote_commitment_txid, ref prev_remote_commitment_txid, .. } = self.key_storage {
+                               if let &Some(ref txid) = current_remote_commitment_txid {
+                                       check_htlc_fails!(txid, "current", 'current_loop);
+                               }
+                               if let &Some(ref txid) = prev_remote_commitment_txid {
+                                       check_htlc_fails!(txid, "previous", 'prev_loop);
+                               }
+                       }
+
                        if let Some(revocation_points) = self.their_cur_revocation_points {
                                let revocation_point_option =
                                        if revocation_points.0 == commitment_number { Some(&revocation_points.1) }
@@ -1407,10 +1443,6 @@ impl ChannelMonitor {
                                                output: spend_tx.output[0].clone(),
                                        });
                                        txn_to_broadcast.push(spend_tx);
-
-                                       // TODO: We need to fail back HTLCs that were't included in the broadcast
-                                       // commitment transaction, either because they didn't meet dust or because a
-                                       // stale (but not yet revoked) commitment transaction was broadcast!
                                }
                        }
                }