From 8df141233f03e6eefae75f3cf1183f00c1cc0aa9 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Wed, 23 Jun 2021 16:39:27 +0000 Subject: [PATCH] Workaround lnd sending funding_locked before channel_reestablish lnd has a long-standing bug where, upon reconnection, if the channel is not yet confirmed they will not send a channel_reestablish until the channel locks in. Then, they will send a funding_locked *before* sending the channel_reestablish (which is clearly a violation of the BOLT specs). We copy c-lightning's workaround here and simply store the funding_locked message until we receive a channel_reestablish. See-also https://github.com/lightningnetwork/lnd/issues/4006 Fixes #963 --- lightning/src/ln/channel.rs | 18 +++++++++++++- lightning/src/ln/channelmanager.rs | 10 ++++++-- lightning/src/ln/functional_tests.rs | 35 +++++++++++++++++++++------- 3 files changed, 51 insertions(+), 12 deletions(-) diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs index f8c8c15b..c46330b5 100644 --- a/lightning/src/ln/channel.rs +++ b/lightning/src/ln/channel.rs @@ -434,6 +434,15 @@ pub(super) struct Channel { next_local_commitment_tx_fee_info_cached: Mutex>, #[cfg(any(test, feature = "fuzztarget"))] next_remote_commitment_tx_fee_info_cached: Mutex>, + + /// lnd has a long-standing bug where, upon reconnection, if the channel is not yet confirmed + /// they will not send a channel_reestablish until the channel locks in. Then, they will send a + /// funding_locked *before* sending the channel_reestablish (which is clearly a violation of + /// the BOLT specs). We copy c-lightning's workaround here and simply store the funding_locked + /// message until we receive a channel_reestablish. + /// + /// See-also + pub workaround_lnd_bug_4006: Option, } #[cfg(any(test, feature = "fuzztarget"))] @@ -633,6 +642,8 @@ impl Channel { next_local_commitment_tx_fee_info_cached: Mutex::new(None), #[cfg(any(test, feature = "fuzztarget"))] next_remote_commitment_tx_fee_info_cached: Mutex::new(None), + + workaround_lnd_bug_4006: None, }) } @@ -876,6 +887,8 @@ impl Channel { next_local_commitment_tx_fee_info_cached: Mutex::new(None), #[cfg(any(test, feature = "fuzztarget"))] next_remote_commitment_tx_fee_info_cached: Mutex::new(None), + + workaround_lnd_bug_4006: None, }; Ok(chan) @@ -1691,7 +1704,8 @@ impl Channel { pub fn funding_locked(&mut self, msg: &msgs::FundingLocked) -> Result<(), ChannelError> { if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 { - return Err(ChannelError::Close("Peer sent funding_locked when we needed a channel_reestablish".to_owned())); + self.workaround_lnd_bug_4006 = Some(msg.clone()); + return Err(ChannelError::Ignore("Peer sent funding_locked when we needed a channel_reestablish. The peer is likely lnd, see https://github.com/lightningnetwork/lnd/issues/4006".to_owned())); } let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS); @@ -4863,6 +4877,8 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel next_local_commitment_tx_fee_info_cached: Mutex::new(None), #[cfg(any(test, feature = "fuzztarget"))] next_remote_commitment_tx_fee_info_cached: Mutex::new(None), + + workaround_lnd_bug_4006: None, }) } } diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index ee266849..dc472b52 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -3365,7 +3365,7 @@ impl ChannelMana } fn internal_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) -> Result<(), MsgHandleErrInternal> { - let (htlcs_failed_forward, chan_restoration_res) = { + let (htlcs_failed_forward, need_lnd_workaround, chan_restoration_res) = { let mut channel_state_lock = self.channel_state.lock().unwrap(); let channel_state = &mut *channel_state_lock; @@ -3386,13 +3386,19 @@ impl ChannelMana msg, }); } - (htlcs_failed_forward, handle_chan_restoration_locked!(self, channel_state_lock, channel_state, chan, revoke_and_ack, commitment_update, order, monitor_update_opt, Vec::new(), None, funding_locked)) + let need_lnd_workaround = chan.get_mut().workaround_lnd_bug_4006.take(); + (htlcs_failed_forward, need_lnd_workaround, + handle_chan_restoration_locked!(self, channel_state_lock, channel_state, chan, revoke_and_ack, commitment_update, order, monitor_update_opt, Vec::new(), None, funding_locked)) }, hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id)) } }; post_handle_chan_restoration!(self, chan_restoration_res); self.fail_holding_cell_htlcs(htlcs_failed_forward, msg.channel_id); + + if let Some(funding_locked_msg) = need_lnd_workaround { + self.internal_funding_locked(counterparty_node_id, &funding_locked_msg)?; + } Ok(()) } diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs index 6298f654..0471cd08 100644 --- a/lightning/src/ln/functional_tests.rs +++ b/lightning/src/ln/functional_tests.rs @@ -3605,15 +3605,20 @@ fn test_simple_peer_disconnect() { fail_payment(&nodes[0], &vec!(&nodes[1], &nodes[2]), payment_hash_6); } -fn do_test_drop_messages_peer_disconnect(messages_delivered: u8) { +fn do_test_drop_messages_peer_disconnect(messages_delivered: u8, simulate_broken_lnd: bool) { // Test that we can reconnect when in-flight HTLC updates get dropped 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 mut nodes = create_network(2, &node_cfgs, &node_chanmgrs); + + let mut as_funding_locked = None; if messages_delivered == 0 { - create_chan_between_nodes_with_value_a(&nodes[0], &nodes[1], 100000, 10001, InitFeatures::known(), InitFeatures::known()); + let (funding_locked, _, _) = create_chan_between_nodes_with_value_a(&nodes[0], &nodes[1], 100000, 10001, InitFeatures::known(), InitFeatures::known()); + as_funding_locked = Some(funding_locked); // nodes[1] doesn't receive the funding_locked message (it'll be re-sent on reconnect) + // Note that we store it so that if we're running with `simulate_broken_lnd` we can deliver + // it before the channel_reestablish message. } else { create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known()); } @@ -3668,6 +3673,17 @@ fn do_test_drop_messages_peer_disconnect(messages_delivered: u8) { nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id(), false); nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id(), false); if messages_delivered < 3 { + if simulate_broken_lnd { + // lnd has a long-standing bug where they send a funding_locked prior to a + // channel_reestablish if you reconnect prior to funding_locked time. + // + // Here we simulate that behavior, delivering a funding_locked immediately on + // reconnect. Note that we don't bother skipping the now-duplicate funding_locked sent + // in `reconnect_nodes` but we currently don't fail based on that. + // + // See-also + nodes[1].node.handle_funding_locked(&nodes[0].node.get_our_node_id(), &as_funding_locked.as_ref().unwrap().0); + } // Even if the funding_locked messages get exchanged, as long as nothing further was // received on either side, both sides will need to resend them. reconnect_nodes(&nodes[0], &nodes[1], (true, true), (0, 1), (0, 0), (0, 0), (0, 0), (false, false)); @@ -3811,17 +3827,18 @@ fn do_test_drop_messages_peer_disconnect(messages_delivered: u8) { #[test] fn test_drop_messages_peer_disconnect_a() { - do_test_drop_messages_peer_disconnect(0); - do_test_drop_messages_peer_disconnect(1); - do_test_drop_messages_peer_disconnect(2); - do_test_drop_messages_peer_disconnect(3); + do_test_drop_messages_peer_disconnect(0, true); + do_test_drop_messages_peer_disconnect(0, false); + do_test_drop_messages_peer_disconnect(1, false); + do_test_drop_messages_peer_disconnect(2, false); } #[test] fn test_drop_messages_peer_disconnect_b() { - do_test_drop_messages_peer_disconnect(4); - do_test_drop_messages_peer_disconnect(5); - do_test_drop_messages_peer_disconnect(6); + do_test_drop_messages_peer_disconnect(3, false); + do_test_drop_messages_peer_disconnect(4, false); + do_test_drop_messages_peer_disconnect(5, false); + do_test_drop_messages_peer_disconnect(6, false); } #[test] -- 2.30.2