Claim HTLCs with preimage from currently confirmed commitment

This ensures that we correctly handle the cases covered by the tests
added in the previous commit. Namely, that we claim the HTLCs from the
currently confirmed commitment, rather than always claiming from the
latest or previous counterparty commitment if we've seen either confirm
onchain at a prior point.

Author: wpaulino

lightning/src/chain/channelmonitor.rs

@@ -2503,6 +2503,18 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 	{
 		self.payment_preimages.insert(payment_hash.clone(), payment_preimage.clone());
 
+		let confirmed_spend_txid = self.funding_spend_confirmed.or_else(|| {
+			self.onchain_events_awaiting_threshold_conf.iter().find_map(|event| match event.event {
+				OnchainEvent::FundingSpendConfirmation { .. } => Some(event.txid),
+				_ => None,
+			})
+		});
+		let confirmed_spend_txid = if let Some(txid) = confirmed_spend_txid {
+			txid
+		} else {
+			return;
+		};
+
 		// If the channel is force closed, try to claim the output from this preimage.
 		// First check if a counterparty commitment transaction has been broadcasted:
 		macro_rules! claim_htlcs {
@@ -2512,14 +2524,24 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 			}
 		}
 		if let Some(txid) = self.current_counterparty_commitment_txid {
-			if let Some(commitment_number) = self.counterparty_commitment_txn_on_chain.get(&txid) {
-				claim_htlcs!(*commitment_number, txid);
+			if txid == confirmed_spend_txid {
+				if let Some(commitment_number) = self.counterparty_commitment_txn_on_chain.get(&txid) {
+					claim_htlcs!(*commitment_number, txid);
+				} else {
+					debug_assert!(false);
+					log_error!(self.logger, "Detected counterparty commitment tx on-chain without tracking commitment number");
+				}
 				return;
 			}
 		}
 		if let Some(txid) = self.prev_counterparty_commitment_txid {
-			if let Some(commitment_number) = self.counterparty_commitment_txn_on_chain.get(&txid) {
-				claim_htlcs!(*commitment_number, txid);
+			if txid == confirmed_spend_txid {
+				if let Some(commitment_number) = self.counterparty_commitment_txn_on_chain.get(&txid) {
+					claim_htlcs!(*commitment_number, txid);
+				} else {
+					debug_assert!(false);
+					log_error!(self.logger, "Detected counterparty commitment tx on-chain without tracking commitment number");
+				}
 				return;
 			}
 		}
@@ -2530,13 +2552,22 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 		// *we* sign a holder commitment transaction, not when e.g. a watchtower broadcasts one of our
 		// holder commitment transactions.
 		if self.broadcasted_holder_revokable_script.is_some() {
-			// Assume that the broadcasted commitment transaction confirmed in the current best
-			// block. Even if not, its a reasonable metric for the bump criteria on the HTLC
-			// transactions.
-			let (claim_reqs, _) = self.get_broadcasted_holder_claims(&self.current_holder_commitment_tx, self.best_block.height());
-			self.onchain_tx_handler.update_claims_view_from_requests(claim_reqs, self.best_block.height(), self.best_block.height(), broadcaster, fee_estimator, logger);
-			if let Some(ref tx) = self.prev_holder_signed_commitment_tx {
-				let (claim_reqs, _) = self.get_broadcasted_holder_claims(&tx, self.best_block.height());
+			let holder_commitment_tx = if self.current_holder_commitment_tx.txid == confirmed_spend_txid {
+				Some(&self.current_holder_commitment_tx)
+			} else if let Some(prev_holder_commitment_tx) = &self.prev_holder_signed_commitment_tx {
+				if prev_holder_commitment_tx.txid == confirmed_spend_txid {
+					Some(prev_holder_commitment_tx)
+				} else {
+					None
+				}
+			} else {
+				None
+			};
+			if let Some(holder_commitment_tx) = holder_commitment_tx {
+				// Assume that the broadcasted commitment transaction confirmed in the current best
+				// block. Even if not, its a reasonable metric for the bump criteria on the HTLC
+				// transactions.
+				let (claim_reqs, _) = self.get_broadcasted_holder_claims(&holder_commitment_tx, self.best_block.height());
 				self.onchain_tx_handler.update_claims_view_from_requests(claim_reqs, self.best_block.height(), self.best_block.height(), broadcaster, fee_estimator, logger);
 			}
 		}