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Locked splice bug fixes during channel reestablishment #4624

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Locked splice bug fixes during channel reestablishment #4624

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ef7e073
Send missing splice_locked when confirmation precedes reestablishment
wpaulino May 12, 2026
24bac54
Handle inferred splice_locked on reestablish first prior to updates
wpaulino May 19, 2026
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31 changes: 30 additions & 1 deletion lightning/src/ln/channel.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1265,6 +1265,7 @@ pub(super) struct ReestablishResponses {
pub shutdown_msg: Option<msgs::Shutdown>,
pub tx_signatures: Option<msgs::TxSignatures>,
pub tx_abort: Option<msgs::TxAbort>,
pub splice_locked: Option<msgs::SpliceLocked>,
pub inferred_splice_locked: Option<msgs::SpliceLocked>,
}

Expand Down Expand Up @@ -3503,6 +3504,12 @@ pub(super) struct ChannelContext<SP: SignerProvider> {
/// See-also <https://github.com/lightningnetwork/lnd/issues/4006>
pub workaround_lnd_bug_4006: Option<msgs::ChannelReady>,

/// The `my_current_funding_locked` txid included in our `channel_reestablish` for the current
/// reconnect, if any. We track this as we cannot tell what was included after we've already
/// sent it, as it's possible it was unconfirmed at the time we sent it, but confirmed shortly
/// after.
funding_locked_txid_sent_in_reestablish: Option<Txid>,

/// An option set when we wish to track how many ticks have elapsed while waiting for a response
/// from our counterparty after entering specific states. If the peer has yet to respond after
/// reaching `DISCONNECT_PEER_AWAITING_RESPONSE_TICKS`, a reconnection should be attempted to
Expand Down Expand Up @@ -4225,6 +4232,7 @@ impl<SP: SignerProvider> ChannelContext<SP> {
announcement_sigs: None,

workaround_lnd_bug_4006: None,
funding_locked_txid_sent_in_reestablish: None,
sent_message_awaiting_response: None,

latest_inbound_scid_alias: None,
Expand Down Expand Up @@ -4536,6 +4544,7 @@ impl<SP: SignerProvider> ChannelContext<SP> {
announcement_sigs: None,

workaround_lnd_bug_4006: None,
funding_locked_txid_sent_in_reestablish: None,
sent_message_awaiting_response: None,

latest_inbound_scid_alias: None,
Expand Down Expand Up @@ -10512,6 +10521,8 @@ where
// remaining cases either succeed or ErrorMessage-fail).
self.context.channel_state.clear_peer_disconnected();
self.mark_response_received();
let funding_locked_txid_sent_in_reestablish =
self.context.funding_locked_txid_sent_in_reestablish.take();

let shutdown_msg = self.get_outbound_shutdown();

Expand Down Expand Up @@ -10663,6 +10674,7 @@ where
shutdown_msg, announcement_sigs,
tx_signatures,
tx_abort: None,
splice_locked: None,
inferred_splice_locked: None,
});
}
Expand All @@ -10676,6 +10688,7 @@ where
shutdown_msg, announcement_sigs,
tx_signatures,
tx_abort,
splice_locked: None,
inferred_splice_locked: None,
});
}
Expand Down Expand Up @@ -10745,6 +10758,15 @@ where
splice_txid,
})
});
let splice_locked = self.pending_splice.as_ref().and_then(|pending_splice| {
pending_splice
.sent_funding_txid
.filter(|splice_txid| Some(*splice_txid) != funding_locked_txid_sent_in_reestablish)
.map(|splice_txid| msgs::SpliceLocked {
channel_id: self.context.channel_id,
splice_txid,
})
});

if msg.next_local_commitment_number == next_counterparty_commitment_number {
if required_revoke.is_some() || self.context.signer_pending_revoke_and_ack {
Expand All @@ -10763,6 +10785,7 @@ where
commitment_order: self.context.resend_order.clone(),
tx_signatures,
tx_abort,
splice_locked,
inferred_splice_locked,
})
} else if msg.next_local_commitment_number == next_counterparty_commitment_number - 1 {
Expand All @@ -10788,6 +10811,7 @@ where
commitment_order: self.context.resend_order.clone(),
tx_signatures: None,
tx_abort,
splice_locked,
inferred_splice_locked,
})
} else {
Expand Down Expand Up @@ -10815,6 +10839,7 @@ where
commitment_order: self.context.resend_order.clone(),
tx_signatures: None,
tx_abort,
splice_locked,
inferred_splice_locked,
})
}
Expand Down Expand Up @@ -12492,6 +12517,9 @@ where
log_info!(logger, "Sending a data_loss_protect with no previous remote per_commitment_secret for channel {}", &self.context.channel_id());
[0;32]
};
let my_current_funding_locked = self.maybe_get_my_current_funding_locked();
self.context.funding_locked_txid_sent_in_reestablish =
my_current_funding_locked.as_ref().map(|funding_locked| funding_locked.txid);
msgs::ChannelReestablish {
channel_id: self.context.channel_id(),
// The protocol has two different commitment number concepts - the "commitment
Expand All @@ -12515,7 +12543,7 @@ where
your_last_per_commitment_secret: remote_last_secret,
my_current_per_commitment_point: dummy_pubkey,
next_funding: self.maybe_get_next_funding(),
my_current_funding_locked: self.maybe_get_my_current_funding_locked(),
my_current_funding_locked,
}
}

Expand Down Expand Up @@ -17196,6 +17224,7 @@ impl<'a, 'b, 'c, ES: EntropySource, SP: SignerProvider>
announcement_sigs,

workaround_lnd_bug_4006: None,
funding_locked_txid_sent_in_reestablish: None,
sent_message_awaiting_response: None,

latest_inbound_scid_alias,
Expand Down
78 changes: 56 additions & 22 deletions lightning/src/ln/channelmanager.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -12365,6 +12365,14 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
})?;
let mut peer_state_lock = peer_state_mutex.lock().unwrap();
let peer_state = &mut *peer_state_lock;
self.internal_channel_ready_with_peer_state(counterparty_node_id, msg, peer_state)
}

#[rustfmt::skip]
fn internal_channel_ready_with_peer_state(
&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReady,
peer_state: &mut PeerState<SP>,
) -> Result<(), MsgHandleErrInternal> {
match peer_state.channel_by_id.entry(msg.channel_id) {
hash_map::Entry::Occupied(mut chan_entry) => {
if let Some(chan) = chan_entry.get_mut().as_funded_mut() {
Expand Down Expand Up @@ -13240,7 +13248,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/

#[rustfmt::skip]
fn internal_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) -> Result<(), MsgHandleErrInternal> {
let (inferred_splice_locked, need_lnd_workaround, holding_cell_res) = {
let (post_splice_locked_update, holding_cell_res) = {
let per_peer_state = self.per_peer_state.read().unwrap();

let peer_state_mutex = per_peer_state.get(counterparty_node_id).ok_or_else(|| {
Expand All @@ -13249,7 +13257,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
let logger = WithContext::from(&self.logger, Some(*counterparty_node_id), Some(msg.channel_id), None);
let mut peer_state_lock = peer_state_mutex.lock().unwrap();
let peer_state = &mut *peer_state_lock;
match peer_state.channel_by_id.entry(msg.channel_id) {
let (inferred_splice_locked, need_lnd_workaround) = match peer_state.channel_by_id.entry(msg.channel_id) {
hash_map::Entry::Occupied(mut chan_entry) => {
if let Some(chan) = chan_entry.get_mut().as_funded_mut() {
// Currently, we expect all holding cell update_adds to be dropped on peer
Expand Down Expand Up @@ -13285,10 +13293,15 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
}
}
let need_lnd_workaround = chan.context.workaround_lnd_bug_4006.take();
let funding_tx_signed = responses.tx_signatures.map(|tx_signatures| FundingTxSigned {
tx_signatures: Some(tx_signatures),
..Default::default()
});
let funding_tx_signed = if responses.tx_signatures.is_some() || responses.splice_locked.is_some() {
Some(FundingTxSigned {
tx_signatures: responses.tx_signatures,
splice_locked: responses.splice_locked,
..Default::default()
})
} else {
None
};
let (htlc_forwards, decode_update_add_htlcs) = self.handle_channel_resumption(
&mut peer_state.pending_msg_events, chan, responses.raa, responses.commitment_update, responses.commitment_order,
Vec::new(), Vec::new(), None, responses.channel_ready, responses.announcement_sigs,
Expand All @@ -13300,8 +13313,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
peer_state.pending_msg_events.push(upd);
}

let holding_cell_res = self.check_free_peer_holding_cells(peer_state);
(responses.inferred_splice_locked, need_lnd_workaround, holding_cell_res)
(responses.inferred_splice_locked, need_lnd_workaround)
} else {
return try_channel_entry!(self, peer_state, Err(ChannelError::close(
"Got a channel_reestablish message for an unfunded channel!".into())), chan_entry);
Expand Down Expand Up @@ -13339,18 +13351,28 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
return Err(MsgHandleErrInternal::no_such_channel_for_peer(counterparty_node_id, msg.channel_id)
)
}
};

if let Some(channel_ready_msg) = need_lnd_workaround {
self.internal_channel_ready_with_peer_state(counterparty_node_id, &channel_ready_msg, peer_state)?;
}
};

self.handle_holding_cell_free_result(holding_cell_res);
// A reestablish may infer a missed `splice_locked`; apply it before freeing holding
// cells so we don't generate commitment updates against stale splice state.
let post_splice_locked_update = if let Some(splice_locked) = inferred_splice_locked {
self.internal_splice_locked_with_peer_state(counterparty_node_id, &splice_locked, peer_state)?
} else {
None
};

if let Some(channel_ready_msg) = need_lnd_workaround {
self.internal_channel_ready(counterparty_node_id, &channel_ready_msg)?;
}
let holding_cell_res = self.check_free_peer_holding_cells(peer_state);
(post_splice_locked_update, holding_cell_res)
};

if let Some(splice_locked) = inferred_splice_locked {
self.internal_splice_locked(counterparty_node_id, &splice_locked)?;
if let Some(data) = post_splice_locked_update {
self.handle_post_monitor_update_chan_resume(data);
}
self.handle_holding_cell_free_result(holding_cell_res);

Ok(())
}
Expand Down Expand Up @@ -13580,8 +13602,24 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
})?;
let mut peer_state_lock = peer_state_mutex.lock().unwrap();
let peer_state = &mut *peer_state_lock;
let post_update_data =
self.internal_splice_locked_with_peer_state(counterparty_node_id, msg, peer_state)?;
mem::drop(peer_state_lock);
mem::drop(per_peer_state);

if let Some(data) = post_update_data {
self.handle_post_monitor_update_chan_resume(data);
}

Ok(())
}

fn internal_splice_locked_with_peer_state(
&self, counterparty_node_id: &PublicKey, msg: &msgs::SpliceLocked,
peer_state: &mut PeerState<SP>,
) -> Result<Option<PostMonitorUpdateChanResume>, MsgHandleErrInternal> {
// Look for the channel
let mut post_update_data = None;
match peer_state.channel_by_id.entry(msg.channel_id) {
hash_map::Entry::Vacant(_) => {
return Err(MsgHandleErrInternal::no_such_channel_for_peer(
Expand Down Expand Up @@ -13643,19 +13681,15 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
}

if let Some(monitor_update) = splice_promotion.monitor_update {
if let Some(data) = self.handle_new_monitor_update(
post_update_data = self.handle_new_monitor_update(
&mut peer_state.in_flight_monitor_updates,
&mut peer_state.monitor_update_blocked_actions,
&mut peer_state.pending_msg_events,
peer_state.is_connected,
chan,
splice_promotion.funding_txo,
monitor_update,
) {
mem::drop(peer_state_lock);
mem::drop(per_peer_state);
self.handle_post_monitor_update_chan_resume(data);
}
);
}
}
} else {
Expand All @@ -13667,7 +13701,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
},
};

Ok(())
Ok(post_update_data)
}

/// Process pending events from the [`chain::Watch`], returning whether any events were processed.
Expand Down
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