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Workaround for LND to cause a force-close on our channel

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Unfortunately LND does not force close the channels on receiving an error,
they blame us for this behaviour (abb1e3463f/htlcswitch/link.go (L2119))

To fix this we will send them a Bogus Channel Reestablish with 0 commitment_number and invalid last_per_commit_secret.

Key Changes:
  - In connect_activate_subd, if we detect a stub channel, we serialize and send a bogus channel_reestablish message.

Changelog-Fixed: Fixing LND's non responsive behaviour on receiving an error.
This commit is contained in:
Aditya Sharma
2025-04-05 14:26:25 +05:30
committed by Rusty Russell
parent 99ef16fd71
commit 39a2893688
1 changed files with 26 additions and 0 deletions
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26
lightningd/peer_control.c
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@@ -1377,6 +1377,32 @@ tell_connectd:
send_error:
log_debug(channel->log, "Telling connectd to send error %s",
tal_hex(tmpctx, error));
/* LND does not respond to errors with a unilateral close
* (https://github.com/lightningnetwork/lnd/blob/abb1e3463f3a83bbb843d5c399869dbe930ad94f/htlcswitch/link.go#L2119).
* We fix this by sending a `ChannelReestablish` msg with `0` commitment numbers and an
* invalid `your_last_per_commitment_secret`. */
if (is_stub_scid(*channel->scid)) {
struct secret your_last_per_commit_secret;
memset(&your_last_per_commit_secret, 1,
sizeof(your_last_per_commit_secret));
const u8 *msg = towire_channel_reestablish(tmpctx, &channel->cid,
0,
0,
&your_last_per_commit_secret,
&channel->channel_info.remote_per_commit,
NULL);
log_debug(channel->log, "Sending a bogus channel_reestablish message to make the peer "
"unilaterally close the channel.");
subd_send_msg(ld->connectd,
take(towire_connectd_peer_send_msg(NULL, &channel->peer->id,
channel->peer->connectd_counter,
msg)));
}
/* Get connectd to send error and close. */
subd_send_msg(ld->connectd,
take(towire_connectd_peer_send_msg(NULL, &channel->peer->id,