+#[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(ChannelId::v1_from_funding_outpoint(funding_output), 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_conflicting_funding_from_second_peer() {
+ // Test that if a user tries to fund a channel with a funding outpoint they'd previously used
+ // we don't try to remove the previous ChannelMonitor. This is largely a test to ensure we
+ // don't regress in the fuzzer, as such funding getting passed our outpoint-matches checks
+ // implies the user (and our counterparty) has reused cryptographic keys across channels, which
+ // we require the user not do.
+ let chanmon_cfgs = create_chanmon_cfgs(4);
+ let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
+ let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
+ let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
+
+ let temp_chan_id = exchange_open_accept_chan(&nodes[0], &nodes[1], 1_000_000, 0);
+
+ let (_, tx, funding_output) =
+ create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 1_000_000, 42);
+
+ // Now that we have a funding outpoint, create a dummy `ChannelMonitor` and insert it into
+ // nodes[0]'s ChainMonitor so that the initial `ChannelMonitor` write fails.
+ let dummy_chan_id = create_chan_between_nodes(&nodes[2], &nodes[3]).3;
+ let dummy_monitor = get_monitor!(nodes[2], dummy_chan_id).clone();
+ nodes[0].chain_monitor.chain_monitor.watch_channel(funding_output, dummy_monitor).unwrap();
+
+ nodes[0].node.funding_transaction_generated(&temp_chan_id, &nodes[1].node.get_our_node_id(), tx.clone()).unwrap();
+
+ let mut funding_created_msg = 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(), &funding_created_msg);
+ let funding_signed_msg = get_event_msg!(nodes[1], MessageSendEvent::SendFundingSigned, nodes[0].node.get_our_node_id());
+ check_added_monitors!(nodes[1], 1);
+ expect_channel_pending_event(&nodes[1], &nodes[0].node.get_our_node_id());
+
+ nodes[0].node.handle_funding_signed(&nodes[1].node.get_our_node_id(), &funding_signed_msg);
+ // At this point, the channel should be closed, after having generated one monitor write (the
+ // watch_channel call which failed), but zero monitor updates.
+ check_added_monitors!(nodes[0], 1);
+ get_err_msg(&nodes[0], &nodes[1].node.get_our_node_id());
+ let err_reason = ClosureReason::ProcessingError { err: "Channel funding outpoint was a duplicate".to_owned() };
+ check_closed_events(&nodes[0], &[ExpectedCloseEvent::from_id_reason(funding_signed_msg.channel_id, true, err_reason)]);
+}
+