Don't attempt to resume channels if we already exchanged funding

ddf75afd16 introduced the ability to re-exchange our `ChannelOpen`
after a peer disconnects if we didn't complete funding on our end.
It did not implement nor consider what would happen if we
re-connected after we created our own funding transactions, and
currently it panics (and even if it did not it would replay the
`FundingTransactionGenerated` event to users).

While we'd very much like to replay the `open_channel` flow even
if we have already received an `accept_channel` and funded the
channel, we cannot as the peer will likely provide different key
material in their `accept_channel`, causing us to need a different
funding transaction.

Thus, here, we simply close channels which have been funded but not
yet signed when our peer disconnects.

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 5fbdb595b77101f8bf455e0761adc9de08437647..793d9af80b2b0e9f4d9574a4af202b1efe734e03 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -7520,6 +7520,12 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                Ok(self.get_open_channel(chain_hash))
        }
 
+       /// Returns true if we can resume the channel by sending the [`msgs::OpenChannel`] again.
+       pub fn is_resumable(&self) -> bool {
+               !self.context.have_received_message() &&
+                       self.context.cur_holder_commitment_transaction_number == INITIAL_COMMITMENT_NUMBER
+       }
+
        pub fn get_open_channel(&self, chain_hash: ChainHash) -> msgs::OpenChannel {
                if !self.context.is_outbound() {
                        panic!("Tried to open a channel for an inbound channel?");

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index f2b3bf15d39608f93d08774c43306cc31f102ac5..f3e0ae5e09fe051707638e7964bcfe23cf43eb38 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -9954,11 +9954,14 @@ where
                                                        }
                                                        &mut chan.context
                                                },
-                                               // We retain UnfundedOutboundV1 channel for some time in case
-                                               // peer unexpectedly disconnects, and intends to reconnect again.
-                                               ChannelPhase::UnfundedOutboundV1(_) => {
-                                                       return true;
-                                               },
+                                               // If we get disconnected and haven't yet committed to a funding
+                                               // transaction, we can replay the `open_channel` on reconnection, so don't
+                                               // bother dropping the channel here. However, if we already committed to
+                                               // the funding transaction we don't yet support replaying the funding
+                                               // handshake (and bailing if the peer rejects it), so we force-close in
+                                               // that case.
+                                               ChannelPhase::UnfundedOutboundV1(chan) if chan.is_resumable() => return true,
+                                               ChannelPhase::UnfundedOutboundV1(chan) => &mut chan.context,
                                                // Unfunded inbound channels will always be removed.
                                                ChannelPhase::UnfundedInboundV1(chan) => {
                                                        &mut chan.context

diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs
index 5b1420e3d6b55b073ff790046831ebd68ad5b56c..3f9e263fcf7c19a5bf460f7d7c12387b8407ec91 100644 (file)
--- a/lightning/src/ln/functional_tests.rs
+++ b/lightning/src/ln/functional_tests.rs
@@ -61,6 +61,38 @@ use crate::ln::chan_utils::CommitmentTransaction;
 
 use super::channel::UNFUNDED_CHANNEL_AGE_LIMIT_TICKS;
 
+#[test]
+fn test_channel_resumption_fail_post_funding() {
+       // If we fail to exchange funding with a peer prior to it disconnecting we'll resume the
+       // channel open on reconnect, however if we do exchange funding we do not currently support
+       // replaying it and here test that the channel closes.
+       let chanmon_cfgs = create_chanmon_cfgs(2);
+       let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+       let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+       nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 1_000_000, 0, 42, None, None).unwrap();
+       let open_chan = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
+       nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_chan);
+       let accept_chan = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
+       nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), &accept_chan);
+
+       let (temp_chan_id, tx, funding_output) =
+               create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 1_000_000, 42);
+       let new_chan_id = ChannelId::v1_from_funding_outpoint(funding_output);
+       nodes[0].node.funding_transaction_generated(&temp_chan_id, &nodes[1].node.get_our_node_id(), tx).unwrap();
+
+       nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id());
+       check_closed_events(&nodes[0], &[ExpectedCloseEvent::from_id_reason(new_chan_id, true, ClosureReason::DisconnectedPeer)]);
+
+       // After ddf75afd16 we'd panic on reconnection if we exchanged funding info, so test that
+       // explicitly here.
+       nodes[0].node.peer_connected(&nodes[1].node.get_our_node_id(), &msgs::Init {
+               features: nodes[1].node.init_features(), networks: None, remote_network_address: None
+       }, true).unwrap();
+       assert_eq!(nodes[0].node.get_and_clear_pending_msg_events(), Vec::new());
+}
+
 #[test]
 fn test_insane_channel_opens() {
        // Stand up a network of 2 nodes
@@ -3738,10 +3770,10 @@ fn test_peer_disconnected_before_funding_broadcasted() {
                nodes[0].node.timer_tick_occurred();
        }
 
-       // Ensure that the channel is closed with `ClosureReason::HolderForceClosed`
-       // when the peers are disconnected and do not reconnect before the funding
-       // transaction is broadcasted.
-       check_closed_event!(&nodes[0], 2, ClosureReason::HolderForceClosed, true
+       // Ensure that the channel is closed with `ClosureReason::DisconnectedPeer` and a
+       // `DiscardFunding` event when the peers are disconnected and do not reconnect before the
+       // funding transaction is broadcasted.
+       check_closed_event!(&nodes[0], 2, ClosureReason::DisconnectedPeer, true
                , [nodes[1].node.get_our_node_id()], 1000000);
        check_closed_event!(&nodes[1], 1, ClosureReason::DisconnectedPeer, false
                , [nodes[0].node.get_our_node_id()], 1000000);