Merge pull request #2101 from TheBlueMatt/2023-03-one-less-sig

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

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index ce68e4273b28b774ae9c6655fd87e4b11b59adb6..89b1fd191deb830d7ce11217c19ad3fe31281fdb 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -3134,9 +3134,24 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
                        return Err(ChannelError::Close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), commitment_stats.num_nondust_htlcs)));
                }
 
-               // TODO: Sadly, we pass HTLCs twice to ChannelMonitor: once via the HolderCommitmentTransaction and once via the update
+               // Up to LDK 0.0.115, HTLC information was required to be duplicated in the
+               // `htlcs_and_sigs` vec and in the `holder_commitment_tx` itself, both of which were passed
+               // in the `ChannelMonitorUpdate`. In 0.0.115, support for having a separate set of
+               // outbound-non-dust-HTLCSources in the `ChannelMonitorUpdate` was added, however for
+               // backwards compatibility, we never use it in production. To provide test coverage, here,
+               // we randomly decide (in test/fuzzing builds) to use the new vec sometimes.
+               #[allow(unused_assignments, unused_mut)]
+               let mut separate_nondust_htlc_sources = false;
+               #[cfg(all(feature = "std", any(test, fuzzing)))] {
+                       use core::hash::{BuildHasher, Hasher};
+                       // Get a random value using the only std API to do so - the DefaultHasher
+                       let rand_val = std::collections::hash_map::RandomState::new().build_hasher().finish();
+                       separate_nondust_htlc_sources = rand_val % 2 == 0;
+               }
+
+               let mut nondust_htlc_sources = Vec::with_capacity(htlcs_cloned.len());
                let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
-               for (idx, (htlc, source)) in htlcs_cloned.drain(..).enumerate() {
+               for (idx, (htlc, mut source_opt)) in htlcs_cloned.drain(..).enumerate() {
                        if let Some(_) = htlc.transaction_output_index {
                                let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
                                        self.get_counterparty_selected_contest_delay().unwrap(), &htlc, self.opt_anchors(),
@@ -3151,10 +3166,18 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
                                if let Err(_) = self.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key) {
                                        return Err(ChannelError::Close("Invalid HTLC tx signature from peer".to_owned()));
                                }
-                               htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source));
+                               if !separate_nondust_htlc_sources {
+                                       htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
+                               }
                        } else {
-                               htlcs_and_sigs.push((htlc, None, source));
+                               htlcs_and_sigs.push((htlc, None, source_opt.take()));
+                       }
+                       if separate_nondust_htlc_sources {
+                               if let Some(source) = source_opt.take() {
+                                       nondust_htlc_sources.push(source);
+                               }
                        }
+                       debug_assert!(source_opt.is_none(), "HTLCSource should have been put somewhere");
                }
 
                let holder_commitment_tx = HolderCommitmentTransaction::new(
@@ -3217,6 +3240,7 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
                                commitment_tx: holder_commitment_tx,
                                htlc_outputs: htlcs_and_sigs,
                                claimed_htlcs,
+                               nondust_htlc_sources,
                        }]
                };