From aabc31cafb329c45f9e1bb070713ae51c89ef8af Mon Sep 17 00:00:00 2001
From: Antoine Riard <ariard@student.42.fr>
Date: Tue, 9 Oct 2018 00:33:59 +0000
Subject: [PATCH] Implement fail backward in case of detection of revoked tx

Refactor block_connected to ease output resolution

Add test_commitment_revoked_fail_backward

Close #137
---
 src/ln/channelmanager.rs | 48 ++++++++++++++++++++++++++++++++++++++++
 src/ln/channelmonitor.rs |  2 ++
 2 files changed, 50 insertions(+)

diff --git a/src/ln/channelmanager.rs b/src/ln/channelmanager.rs
index c1e284a00..ca85f6fce 100644
--- a/src/ln/channelmanager.rs
+++ b/src/ln/channelmanager.rs
@@ -6342,6 +6342,54 @@ mod tests {
 		assert_eq!(node_txn[2].clone().input[0].witness.last().unwrap().len(), 133);
 	}
 
+	#[test]
+	fn test_commitment_revoked_fail_backward() {
+		// Test that in case of a revoked commitment tx, we detect the resolution of output by justice tx
+		// and fail backward accordingly.
+
+		let nodes = create_network(3);
+
+		// Create some initial channels
+		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 through 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);
+		// Get the will-be-revoked local txn from nodes[2]
+		let revoked_local_txn = nodes[2].node.channel_state.lock().unwrap().by_id.get(&chan_2.2).unwrap().last_local_commitment_txn.clone();
+		// Revoke the old state
+		claim_payment(&nodes[0], &vec!(&nodes[1], &nodes[2])[..], payment_preimage);
+
+		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};
+		nodes[1].chain_monitor.block_connected_with_filtering(&Block { header, txdata: vec![revoked_local_txn[0].clone()] }, 1);
+		{
+			let mut added_monitors = nodes[1].chan_monitor.added_monitors.lock().unwrap();
+			assert_eq!(added_monitors.len(), 1);
+			added_monitors.clear();
+		}
+		let events = nodes[1].node.get_and_clear_pending_msg_events();
+		assert_eq!(events.len(), 2);
+		match events[0] {
+			MessageSendEvent::BroadcastChannelUpdate { msg: msgs::ChannelUpdate { .. } } => {},
+			_ => panic!("Unexpected event"),
+		}
+		match events[1] {
+			MessageSendEvent::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"),
+		}
+	}
+
 	#[test]
 	fn test_htlc_ignore_latest_remote_commitment() {
 		// Test that HTLC transactions spending the latest remote commitment transaction are simply
diff --git a/src/ln/channelmonitor.rs b/src/ln/channelmonitor.rs
index ff58fdd14..f782b68b4 100644
--- a/src/ln/channelmonitor.rs
+++ b/src/ln/channelmonitor.rs
@@ -274,6 +274,7 @@ impl<Key : Send + cmp::Eq + hash::Hash + 'static> SimpleManyChannelMonitor<Key>
 		monitors.insert(key, monitor);
 		Ok(())
 	}
+
 }
 
 impl ManyChannelMonitor for SimpleManyChannelMonitor<OutPoint> {
@@ -1931,6 +1932,7 @@ impl ChannelMonitor {
 		}
 		htlc_updated
 	}
+
 }
 
 const MAX_ALLOC_SIZE: usize = 64*1024;
-- 
2.39.5