Add timeout detection in block_connected to fail htlc

backward

Add test for onchain resolution of channel with a timeout, passing
expiration backward

Author: Antoine Riard

src/ln/channelmanager.rs

@@ -2005,13 +2005,17 @@ impl ChainListener for ChannelManager {
 						for (arr, vec) in payment_preimage.iter_mut().zip(tx.input[0].witness[3].iter()) {
 							*arr = *vec;
 						}
-						hash_to_remove.push((payment_preimage, htlc_with_hash.clone()));
+						hash_to_remove.push((Some(payment_preimage), htlc_with_hash.clone()));
 					} else if tx.input.len() > 0 && tx.input[0].witness.len() == 3 && tx.input[0].witness[2].len() == 133 && payment_hash160 == tx.input[0].witness[2][109..129] {
 						let mut payment_preimage = [0; 32];
 						for (arr, vec) in payment_preimage.iter_mut().zip(tx.input[0].witness[1].iter()) {
 							*arr = *vec;
 						}
-						hash_to_remove.push((payment_preimage, htlc_with_hash.clone()));
+						hash_to_remove.push((Some(payment_preimage), htlc_with_hash.clone()));
+					} else if tx.input.len() > 0 && tx.input[0].witness.len() == 5 && tx.input[0].witness[4].len() == 133 && payment_hash160 == tx.input[0].witness[4][109..129] {
+						hash_to_remove.push((None, htlc_with_hash.clone()));
+					} else if tx.input.len() > 0 && tx.input[0].witness.len() == 3 && tx.input[0].witness[2].len() == 138 && payment_hash160 == tx.input[0].witness[2][69..89] {
+						hash_to_remove.push((None, htlc_with_hash.clone()));
 					}
 				}
 			}
@@ -2022,11 +2026,20 @@ impl ChainListener for ChannelManager {
 
 		{
 			let mut channel_state = Some(self.channel_state.lock().unwrap());
-			for (preimage, hash) in hash_to_remove {
-				if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap());}
-				if let Some(mut entry) = channel_state.as_mut().unwrap().claimable_htlcs.remove_entry(&hash) {
-					for source in entry.1.drain(..) {
-						self.claim_funds_internal(channel_state.take().unwrap(), HTLCSource::PreviousHopData(source), preimage);
+			for (payment_preimage, payment_hash) in hash_to_remove {
+				if let Some(preimage) = payment_preimage {
+					if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap());}
+					if let Some(mut entry) = channel_state.as_mut().unwrap().claimable_htlcs.remove(&payment_hash) {
+						for source in entry.drain(..) {
+							self.claim_funds_internal(channel_state.take().unwrap(), HTLCSource::PreviousHopData(source), preimage);
+						}
+					}
+				} else {
+					if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap());}
+					if let Some(mut entry) = channel_state.as_mut().unwrap().claimable_htlcs.remove(&payment_hash) {
+						for source in entry.drain(..) {
+							self.fail_htlc_backwards_internal(channel_state.take().unwrap(), HTLCSource::PreviousHopData(source), &payment_hash, HTLCFailReason::Reason { failure_code: 0x1000 | 14, data: Vec::new() });
+						}
 					}
 				}
 			}
@@ -3569,6 +3582,102 @@ mod tests {
 		}
 	}
 
+	#[test]
+	fn test_htlc_on_chain_timeout() {
+		// Test that in case of an unilateral close onchain, we detect the state of output thanks to
+		// ChainWatchInterface and timeout the HTLC  bacward accordingly. So here we test that ChannelManager is
+		// broadcasting the right event to other nodes in payment path.
+		// A ------------------> B ----------------------> C (timeout)
+		//    A's commitment tx 		C's commitment tx
+		//    	      \                                  \
+		//    	   B's HTLC timeout tx		     B's timeout tx
+
+		let nodes = create_network(3);
+
+		// Create some intial channels
+		let chan_1 = create_announced_chan_between_nodes(&nodes, 0, 1);
+		let chan_2 = create_announced_chan_between_nodes(&nodes, 1, 2);
+
+		// Rebalance the network a bit by relaying one payment thorugh all the channels...
+		send_payment(&nodes[0], &vec!(&nodes[1], &nodes[2])[..], 8000000);
+		send_payment(&nodes[0], &vec!(&nodes[1], &nodes[2])[..], 8000000);
+
+		let (payment_preimage, payment_hash) = route_payment(&nodes[0], &vec!(&nodes[1], &nodes[2]), 3000000);
+		let header = BlockHeader { version: 0x20000000, prev_blockhash: Default::default(), merkle_root: Default::default(), time: 42, bits: 42, nonce: 42};
+
+		// Brodacast legit commitment tx from C on B's chain
+		let commitment_tx = nodes[2].node.channel_state.lock().unwrap().by_id.get(&chan_2.2).unwrap().last_local_commitment_txn.clone();
+		nodes[2].node.fail_htlc_backwards(&payment_hash);
+		{
+			let mut added_monitors = nodes[2].chan_monitor.added_monitors.lock().unwrap();
+			assert_eq!(added_monitors.len(), 1);
+			added_monitors.clear();
+		}
+		let events = nodes[2].node.get_and_clear_pending_events();
+		assert_eq!(events.len(), 1);
+		match events[0] {
+			Event::UpdateHTLCs { ref node_id, updates: msgs::CommitmentUpdate { ref update_add_htlcs, ref update_fulfill_htlcs, ref update_fail_htlcs, ref update_fail_malformed_htlcs, .. } } => {
+				assert!(update_add_htlcs.is_empty());
+				assert!(!update_fail_htlcs.is_empty());
+				assert!(update_fulfill_htlcs.is_empty());
+				assert!(update_fail_malformed_htlcs.is_empty());
+				assert_eq!(nodes[1].node.get_our_node_id(), *node_id);
+			},
+			_ => panic!("Unexpected event"),
+		};
+		nodes[2].chain_monitor.block_connected_with_filtering(&Block { header, txdata: vec![commitment_tx[0].clone()]}, 1);
+		let events = nodes[2].node.get_and_clear_pending_events();
+		assert_eq!(events.len(), 1);
+		match events[0] {
+			Event::BroadcastChannelUpdate { msg: msgs::ChannelUpdate { .. } } => {},
+			_ => panic!("Unexpected event"),
+		}
+		let node_txn = nodes[2].tx_broadcaster.txn_broadcasted.lock().unwrap().clone();
+
+		// Broadcast timeout transaction by B on received output fron C's commitment tx on B's chain
+		// Verify that B's ChannelManager is able to detect that HTLC is timeout by its own tx and react backward in consequence
+		nodes[1].chain_monitor.block_connected_with_filtering(&Block { header, txdata: node_txn}, 200);
+		let node_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().clone(); //TODO: shouldn't be a HTLC-Timeout but actually that's one... => implement lacking parts  in check_spend_remote_transaction
+		nodes[1].chain_monitor.block_connected_with_filtering(&Block { header, txdata: node_txn}, 1);
+		let events = nodes[1].node.get_and_clear_pending_events();
+		assert_eq!(events.len(), 2);
+		match events[0] {
+			Event::BroadcastChannelUpdate { msg: msgs::ChannelUpdate { .. } } => {},
+			_ => panic!("Unexpected event"),
+		}
+		match events[1] {
+			Event::UpdateHTLCs { ref node_id, updates: msgs::CommitmentUpdate { ref update_add_htlcs, ref update_fail_htlcs, ref update_fulfill_htlcs, ref update_fail_malformed_htlcs, .. } } => {
+				assert!(update_add_htlcs.is_empty());
+				assert!(!update_fail_htlcs.is_empty());
+				assert!(update_fulfill_htlcs.is_empty());
+				assert!(update_fail_malformed_htlcs.is_empty());
+				assert_eq!(nodes[0].node.get_our_node_id(), *node_id);
+			},
+			_ => panic!("Unexpected event"),
+		};
+
+		// Broadcast legit commitment tx from A on B's chain
+		// Broadcast HTLC Timeout tx by B on offered output from A commitment tx on A's chain
+		let commitment_tx = nodes[0].node.channel_state.lock().unwrap().by_id.get(&chan_1.2).unwrap().last_local_commitment_txn.clone();
+		nodes[1].chain_monitor.block_connected_with_filtering(&Block { header, txdata: vec![commitment_tx[0].clone()]}, 1);
+		let events = nodes[1].node.get_and_clear_pending_events();
+		assert_eq!(events.len(), 1);
+		match events[0] {
+			Event::BroadcastChannelUpdate { msg: msgs::ChannelUpdate { .. } } => {},
+			_ => panic!("Unexpected event"),
+		}
+		let node_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().clone();
+
+		// Verify that A's ChannelManager is able to detect that HTLC is timeout by a HTLC Timeout tx and react backward in consequence
+		nodes[0].chain_monitor.block_connected_with_filtering(&Block { header, txdata: node_txn }, 1);
+		let events = nodes[0].node.get_and_clear_pending_events();
+		assert_eq!(events.len(), 1);
+		match events[0] {
+			Event::BroadcastChannelUpdate { msg: msgs::ChannelUpdate { .. } } => {},
+			_ => panic!("Unexpected event"),
+		}
+	}
+
 	fn test_htlc_ignore_latest_remote_commitment() {
 		// Test that HTLC transactions spending the latest remote commitment transaction are simply
 		// ignored if we cannot claim them. This originally tickled an invalid unwrap().