Do not panic if a peer learns our funding info before we fund

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

diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs
index f86eb53e283501dbaeaeae3cc83e79ba1d679aa2..9777ad75d2337edfa73267a29a1e398cf89284c5 100644 (file)
--- a/lightning/src/ln/functional_tests.rs
+++ b/lightning/src/ln/functional_tests.rs
@@ -8977,6 +8977,61 @@ fn test_duplicate_temporary_channel_id_from_different_peers() {
        }
 }
 
+#[test]
+fn test_peer_funding_sidechannel() {
+       // Test that if a peer somehow learns which txid we'll use for our channel funding before we
+       // receive `funding_transaction_generated` the peer cannot cause us to crash. We'd previously
+       // assumed that LDK would receive `funding_transaction_generated` prior to our peer learning
+       // the txid and panicked if the peer tried to open a redundant channel to us with the same
+       // funding outpoint.
+       //
+       // While this assumption is generally safe, some users may have out-of-band protocols where
+       // they notify their LSP about a funding outpoint first, or this may be violated in the future
+       // with collaborative transaction construction protocols, i.e. dual-funding.
+       let chanmon_cfgs = create_chanmon_cfgs(3);
+       let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
+       let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
+
+       let temp_chan_id_ab = exchange_open_accept_chan(&nodes[0], &nodes[1], 1_000_000, 0);
+       let temp_chan_id_ca = exchange_open_accept_chan(&nodes[2], &nodes[0], 1_000_000, 0);
+
+       let (_, tx, funding_output) =
+               create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 1_000_000, 42);
+
+       let cs_funding_events = nodes[2].node.get_and_clear_pending_events();
+       assert_eq!(cs_funding_events.len(), 1);
+       match cs_funding_events[0] {
+               Event::FundingGenerationReady { .. } => {}
+               _ => panic!("Unexpected event {:?}", cs_funding_events),
+       }
+
+       nodes[2].node.funding_transaction_generated_unchecked(&temp_chan_id_ca, &nodes[0].node.get_our_node_id(), tx.clone(), funding_output.index).unwrap();
+       let funding_created_msg = get_event_msg!(nodes[2], MessageSendEvent::SendFundingCreated, nodes[0].node.get_our_node_id());
+       nodes[0].node.handle_funding_created(&nodes[2].node.get_our_node_id(), &funding_created_msg);
+       get_event_msg!(nodes[0], MessageSendEvent::SendFundingSigned, nodes[2].node.get_our_node_id());
+       expect_channel_pending_event(&nodes[0], &nodes[2].node.get_our_node_id());
+       check_added_monitors!(nodes[0], 1);
+
+       let res = nodes[0].node.funding_transaction_generated(&temp_chan_id_ab, &nodes[1].node.get_our_node_id(), tx.clone());
+       let err_msg = format!("{:?}", res.unwrap_err());
+       assert!(err_msg.contains("An existing channel using outpoint "));
+       assert!(err_msg.contains(" is open with peer"));
+       // Even though the last funding_transaction_generated errored, it still generated a
+       // SendFundingCreated. However, when the peer responds with a funding_signed it will send the
+       // appropriate error message.
+       let as_funding_created = get_event_msg!(nodes[0], MessageSendEvent::SendFundingCreated, nodes[1].node.get_our_node_id());
+       nodes[1].node.handle_funding_created(&nodes[0].node.get_our_node_id(), &as_funding_created);
+       check_added_monitors!(nodes[1], 1);
+       expect_channel_pending_event(&nodes[1], &nodes[0].node.get_our_node_id());
+       let reason = ClosureReason::ProcessingError { err: format!("An existing channel using outpoint {} is open with peer {}", funding_output, nodes[2].node.get_our_node_id()), };
+       check_closed_events(&nodes[0], &[ExpectedCloseEvent::from_id_reason(funding_output.to_channel_id(), true, reason)]);
+
+       let funding_signed = get_event_msg!(nodes[1], MessageSendEvent::SendFundingSigned, nodes[0].node.get_our_node_id());
+       nodes[0].node.handle_funding_signed(&nodes[1].node.get_our_node_id(), &funding_signed);
+       get_err_msg(&nodes[0], &nodes[1].node.get_our_node_id());
+}
+
 #[test]
 fn test_duplicate_funding_err_in_funding() {
        // Test that if we have a live channel with one peer, then another peer comes along and tries