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splice_locked + channel_reestablish bug fixes #4654

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splice_locked + channel_reestablish bug fixes #4654

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3b3ed67
Send splice_locked for promoted splice on reconnect
wpaulino Jun 1, 2026
dd6fdb0
Send splice_locked before reestablish commitment
wpaulino Jun 1, 2026
629f511
Clear stale monitor pending resends on reestablish
wpaulino Jun 1, 2026
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18 changes: 18 additions & 0 deletions lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10714,6 +10714,9 @@ where
let required_revoke = if msg.next_remote_commitment_number == our_commitment_transaction {
// Remote isn't waiting on any RevokeAndACK from us!
// Note that if we need to repeat our ChannelReady we'll do that in the next if block.
// If a stale ChannelManager replayed a completed update, the monitor-pending state may
// still think we owe one; the reestablish proof is authoritative here.
self.context.monitor_pending_revoke_and_ack = false;
None
} else if msg.next_remote_commitment_number + 1 == our_commitment_transaction {
if self.context.channel_state.is_monitor_update_in_progress() {
Expand Down Expand Up @@ -10784,9 +10787,24 @@ where
channel_id: self.context.channel_id,
splice_txid,
})
}).or_else(|| {
// If a splice confirms after we've sent `channel_reestablish` but before we've
// received theirs, we may promote the splice while disconnected and clear
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@jkczyz jkczyz Jun 3, 2026

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I don't understand the "we may promote the splice while disconnected and clear" part. Isn't the fact that we've sent channel_reestablish indicate we are connected? Should this have said, "we may have promoted the splice while disconnected and have cleared"?

Commit message is similarly confusing to me.

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@wpaulino wpaulino Jun 3, 2026

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Disconnected as in the PEER_DISCONNECTED state flag, i.e., the channel not being reestablished yet.

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@jkczyz jkczyz Jun 3, 2026

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Ah, ok. Could you rephrase the comment for clarity?

// `pending_splice`. We still need to send `splice_locked` after reestablishing
// unless the promoted txid was already included in our `channel_reestablish`.
let current_funding_txid = self.funding.get_funding_txid()?;
(self.funding.channel_transaction_parameters.splice_parent_funding_txid.is_some()
&& Some(current_funding_txid) != funding_locked_txid_sent_in_reestablish)
.then(|| msgs::SpliceLocked {
channel_id: self.context.channel_id,
splice_txid: current_funding_txid,
})
});
Comment on lines +10790 to 10802
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@ldk-claude-review-bot ldk-claude-review-bot Jun 1, 2026

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This or_else fires whenever the first closure returns None, which happens not only when self.pending_splice is None (the intended case per the comment), but also when self.pending_splice is Some and sent_funding_txid was filtered out because it matched funding_locked_txid_sent_in_reestablish.

In a sequential-splice scenario (first splice promoted, second splice negotiated and confirmed locally, then reconnect), this would send splice_locked for the previously promoted splice's txid. If the peer has already promoted that splice and has a pending_splice for the second splice, their splice_locked handler would check negotiated_candidates for the old txid, not find it, and force-close the channel with "unknown splice funding txid".

Consider adding self.pending_splice.is_none() to the guard to match the comment's intent—this branch should only handle the case where pending_splice was cleared due to promotion:

Suggested change
}).or_else(|| {
// If a splice confirms after we've sent `channel_reestablish` but before we've
// received theirs, we may promote the splice while disconnected and clear
// `pending_splice`. We still need to send `splice_locked` after reestablishing
// unless the promoted txid was already included in our `channel_reestablish`.
let current_funding_txid = self.funding.get_funding_txid()?;
(self.funding.channel_transaction_parameters.splice_parent_funding_txid.is_some()
&& Some(current_funding_txid) != funding_locked_txid_sent_in_reestablish)
.then(|| msgs::SpliceLocked {
channel_id: self.context.channel_id,
splice_txid: current_funding_txid,
})
});
}).or_else(|| {
// If a splice confirms after we've sent `channel_reestablish` but before we've
// received theirs, we may promote the splice while disconnected and clear
// `pending_splice`. We still need to send `splice_locked` after reestablishing
// unless the promoted txid was already included in our `channel_reestablish`.
let current_funding_txid = self.funding.get_funding_txid()?;
(self.pending_splice.is_none()
&& self.funding.channel_transaction_parameters.splice_parent_funding_txid.is_some()
&& Some(current_funding_txid) != funding_locked_txid_sent_in_reestablish)
.then(|| msgs::SpliceLocked {
channel_id: self.context.channel_id,
splice_txid: current_funding_txid,
})


if msg.next_local_commitment_number == next_counterparty_commitment_number {
// Likewise, don't let a stale monitor-pending resend survive when they tell us
// they've already received our latest commitment.
self.context.monitor_pending_commitment_signed = false;
if required_revoke.is_some() || self.context.signer_pending_revoke_and_ack {
log_debug!(logger, "Reconnected with only lost outbound RAA");
} else {
Expand Down
52 changes: 26 additions & 26 deletions lightning/src/ln/channelmanager.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11052,6 +11052,32 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
}
}


if let Some(funding_tx_signed) = funding_tx_signed.as_ref() {
// These [`FundingTxSigned`] fields are only expected as a result of calling
// [`ChannelManager::funding_transaction_signed`].
debug_assert!(funding_tx_signed.commitment_signed.is_none());
debug_assert!(funding_tx_signed.counterparty_initial_commitment_signed_result.is_none());
}
if let Some(msg) = funding_tx_signed.as_mut().and_then(|v| v.tx_signatures.take()) {
pending_msg_events.push(MessageSendEvent::SendTxSignatures {
node_id: counterparty_node_id,
msg,
});
}
if let Some(msg) = tx_abort {
pending_msg_events.push(MessageSendEvent::SendTxAbort {
node_id: counterparty_node_id,
msg,
});
}
if let Some(msg) = funding_tx_signed.as_mut().and_then(|v| v.splice_locked.take()) {
pending_msg_events.push(MessageSendEvent::SendSpliceLocked {
node_id: counterparty_node_id,
msg,
});
}

macro_rules! handle_cs { () => {
if let Some(update) = commitment_update {
pending_msg_events.push(MessageSendEvent::UpdateHTLCs {
Expand Down Expand Up @@ -11080,25 +11106,6 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
},
}

if let Some(funding_tx_signed) = funding_tx_signed.as_ref() {
// These [`FundingTxSigned`] fields are only expected as a result of calling
// [`ChannelManager::funding_transaction_signed`].
debug_assert!(funding_tx_signed.commitment_signed.is_none());
debug_assert!(funding_tx_signed.counterparty_initial_commitment_signed_result.is_none());
}
if let Some(msg) = funding_tx_signed.as_mut().and_then(|v| v.tx_signatures.take()) {
pending_msg_events.push(MessageSendEvent::SendTxSignatures {
node_id: counterparty_node_id,
msg,
});
}
if let Some(msg) = tx_abort {
pending_msg_events.push(MessageSendEvent::SendTxAbort {
node_id: counterparty_node_id,
msg,
});
}

if let ChannelReadyOrder::SignaturesFirst = channel_ready_order {
if let Some(msg) = channel_ready {
self.send_channel_ready(pending_msg_events, channel, msg);
Expand All @@ -11111,13 +11118,6 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
});
}
}

if let Some(msg) = funding_tx_signed.as_mut().and_then(|v| v.splice_locked.take()) {
pending_msg_events.push(MessageSendEvent::SendSpliceLocked {
node_id: counterparty_node_id,
msg,
});
}
} else if let Some(msg) = channel_ready {
self.send_channel_ready(pending_msg_events, channel, msg);
}
Expand Down
2 changes: 1 addition & 1 deletion lightning/src/ln/functional_test_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1023,7 +1023,7 @@ pub fn get_updates_and_revoke<CM: AChannelManager, H: NodeHolder<CM = CM>>(
macro_rules! get_event_msg {
($node: expr, $event_type: path, $node_id: expr) => {{
let events = $node.node.get_and_clear_pending_msg_events();
assert_eq!(events.len(), 1);
assert_eq!(events.len(), 1, "{events:?}");
match events[0] {
$event_type { ref node_id, ref msg } => {
assert_eq!(*node_id, $node_id);
Expand Down
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