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Allow cancellation of pending splice funding negotiations #4490

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6bad3fd
Allow cancellation of pending splice funding negotiations
wpaulino Mar 13, 2026
7ab9d6f
Rename should_reset_pending_splice_state argument
wpaulino Mar 19, 2026
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8 changes: 5 additions & 3 deletions lightning/src/events/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1833,7 +1833,7 @@ pub enum Event {
invoice_request: InvoiceRequest,
},
/// Indicates that a channel funding transaction constructed interactively is ready to be
/// signed. This event will only be triggered if at least one input was contributed.
/// signed. This event will only be triggered if a contribution was made to the transaction.
///
/// The transaction contains all inputs and outputs provided by both parties including the
/// channel's funding output and a change output if applicable.
Expand All @@ -1844,8 +1844,9 @@ pub enum Event {
/// Each signature MUST use the `SIGHASH_ALL` flag to avoid invalidation of the initial commitment and
/// hence possible loss of funds.
///
/// After signing, call [`ChannelManager::funding_transaction_signed`] with the (partially) signed
/// funding transaction.
/// After signing, call [`ChannelManager::funding_transaction_signed`] with the (partially)
/// signed funding transaction. For splices where you contributed inputs or outputs, call
/// [`ChannelManager::cancel_funding_contributed`] instead if you no longer wish to proceed.
///
/// Generated in [`ChannelManager`] message handling.
///
Expand All @@ -1854,6 +1855,7 @@ pub enum Event {
/// returning `Err(ReplayEvent ())`), but will only be regenerated as needed after restarts.
///
/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
/// [`ChannelManager::cancel_funding_contributed`]: crate::ln::channelmanager::ChannelManager::cancel_funding_contributed
/// [`ChannelManager::funding_transaction_signed`]: crate::ln::channelmanager::ChannelManager::funding_transaction_signed
FundingTransactionReadyForSigning {
/// The `channel_id` of the channel which you'll need to pass back into
Expand Down
110 changes: 79 additions & 31 deletions lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1712,7 +1712,7 @@ where
if matches!(chan.context.channel_state, ChannelState::ChannelReady(_)) {
chan.context.channel_state.clear_local_stfu_sent();
chan.context.channel_state.clear_remote_stfu_sent();
if chan.should_reset_pending_splice_state(false) {
if chan.should_reset_pending_splice_state(true) {
// If there was a pending splice negotiation that failed due to disconnecting, we
// also take the opportunity to clean up our state.
let splice_funding_failed = chan.reset_pending_splice_state();
Expand Down Expand Up @@ -1828,7 +1828,7 @@ where
(None, false)
},
ChannelPhase::Funded(funded_channel) => {
if funded_channel.should_reset_pending_splice_state(false) {
if funded_channel.should_reset_pending_splice_state(true) {
(funded_channel.reset_pending_splice_state(), true)
} else {
debug_assert!(false, "We should never fail an interactive funding negotiation once we're exchanging tx_signatures");
Expand Down Expand Up @@ -2020,7 +2020,7 @@ where
"Received tx_abort while awaiting tx_signatures exchange".to_owned(),
));
}
if funded_channel.should_reset_pending_splice_state(true) {
if funded_channel.should_reset_pending_splice_state(false) {
let has_funding_negotiation = funded_channel
.pending_splice
.as_ref()
Expand Down Expand Up @@ -7156,7 +7156,7 @@ where

fn maybe_fail_splice_negotiation(&mut self) -> Option<SpliceFundingFailed> {
if matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
if self.should_reset_pending_splice_state(false) {
if self.should_reset_pending_splice_state(true) {
self.reset_pending_splice_state()
} else {
self.abandon_quiescent_action()
Expand Down Expand Up @@ -7213,7 +7213,7 @@ where

/// Returns a boolean indicating whether we should reset the splice's
/// [`PendingFunding::funding_negotiation`].
fn should_reset_pending_splice_state(&self, counterparty_aborted: bool) -> bool {
fn should_reset_pending_splice_state(&self, allow_resumption: bool) -> bool {
self.pending_splice
.as_ref()
.map(|pending_splice| {
Expand All @@ -7225,16 +7225,18 @@ where
funding_negotiation,
FundingNegotiation::AwaitingSignatures { .. }
);
if counterparty_aborted {
if allow_resumption {
// If we want to resume the negotiation after reconnecting, we must be
// in [`FundingNegotiation::AwaitingSignatures`] to not reset our state.
!is_awaiting_signatures
} else {
!is_awaiting_signatures
|| !self
.context()
.interactive_tx_signing_session
.as_ref()
.expect("We have a pending splice awaiting signatures")
.has_received_commitment_signed()
} else {
!is_awaiting_signatures
}
})
.unwrap_or_else(|| {
Expand All @@ -7248,7 +7250,7 @@ where
}

fn reset_pending_splice_state(&mut self) -> Option<SpliceFundingFailed> {
debug_assert!(self.should_reset_pending_splice_state(true));
debug_assert!(self.should_reset_pending_splice_state(false));

// Only clear the signing session if the current round is mid-signing. When an earlier
// round completed signing and a later RBF round is in AwaitingAck or
Expand Down Expand Up @@ -7308,7 +7310,7 @@ where
}

pub(super) fn maybe_splice_funding_failed(&self) -> Option<SpliceFundingFailed> {
if !self.should_reset_pending_splice_state(false) {
if !self.should_reset_pending_splice_state(true) {
return None;
}

Expand Down Expand Up @@ -12659,30 +12661,76 @@ where
}
}

#[cfg(test)]
pub fn abandon_splice(
&mut self,
) -> Result<(msgs::TxAbort, Option<SpliceFundingFailed>), APIError> {
if self.should_reset_pending_splice_state(false) {
let tx_abort =
msgs::TxAbort { channel_id: self.context.channel_id(), data: Vec::new() };
let splice_funding_failed = self.reset_pending_splice_state();
Ok((tx_abort, splice_funding_failed))
} else if self.has_pending_splice_awaiting_signatures() {
Err(APIError::APIMisuseError {
pub fn cancel_funding_contributed(&mut self) -> Result<InteractiveTxMsgError, APIError> {
let funding_negotiation = self
.pending_splice
.as_ref()
.and_then(|pending_splice| pending_splice.funding_negotiation.as_ref());
let Some(funding_negotiation) = funding_negotiation else {
return Err(APIError::APIMisuseError {
err: format!(
"Channel {} splice cannot be abandoned; already awaiting signatures",
self.context.channel_id(),
"Channel {} does not have a pending splice negotiation",
self.context.channel_id()
),
})
} else {
Err(APIError::APIMisuseError {
});
};

let made_contribution = match funding_negotiation {
FundingNegotiation::AwaitingAck { context, .. } => {
context.contributed_inputs().next().is_some()
|| context.contributed_outputs().next().is_some()
},
FundingNegotiation::ConstructingTransaction { interactive_tx_constructor, .. } => {
interactive_tx_constructor.contributed_inputs().next().is_some()
|| interactive_tx_constructor.contributed_outputs().next().is_some()
},
FundingNegotiation::AwaitingSignatures { .. } => self
.context
.interactive_tx_signing_session
.as_ref()
.expect("We have a pending splice awaiting signatures")
.has_local_contribution(),
};
if !made_contribution {
return Err(APIError::APIMisuseError {
err: format!(
"Channel {} splice cannot be abandoned; no pending splice",
self.context.channel_id(),
"Channel {} has a pending splice negotiation with no contribution made",
self.context.channel_id()
),
})
});
}

// We typically don't reset the pending funding negotiation when we're in
// [`FundingNegotiation::AwaitingSignatures`] since we're able to resume it on
// re-establishment, so we still need to handle this case separately if the user wishes to
// cancel. If they've yet to call [`Channel::funding_transaction_signed`], then we can
// guarantee to never have sent any signatures to the counterparty, or have processed any
// signatures from them.
if matches!(funding_negotiation, FundingNegotiation::AwaitingSignatures { .. }) {
let already_signed = self
.context
.interactive_tx_signing_session
.as_ref()
.expect("We have a pending splice awaiting signatures")
.has_holder_tx_signatures();
if already_signed {
return Err(APIError::APIMisuseError {
err: format!(
"Channel {} has pending splice negotiation that was already signed",
self.context.channel_id(),
),
});
}
}

debug_assert!(self.context.channel_state.is_quiescent());
let splice_funding_failed = self.reset_pending_splice_state();
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@jkczyz jkczyz Mar 19, 2026

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Do we need to worry about updating PendingFunding::contributions when reseting? This may be a pre-existing issue, though.

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@wpaulino wpaulino Apr 8, 2026

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Already fixed in a547960.

debug_assert!(splice_funding_failed.is_some());
Ok(InteractiveTxMsgError {
err: ChannelError::Abort(AbortReason::ManualIntervention),
splice_funding_failed,
exited_quiescence: true,
})
}

/// Checks during handling splice_init
Expand Down Expand Up @@ -15377,7 +15425,7 @@ impl<SP: SignerProvider> Writeable for FundedChannel<SP> {
ChannelState::ChannelReady(_) => {
channel_state.clear_local_stfu_sent();
channel_state.clear_remote_stfu_sent();
if self.should_reset_pending_splice_state(false)
if self.should_reset_pending_splice_state(true)
|| !self.has_pending_splice_awaiting_signatures()
{
// We shouldn't be quiescent anymore upon reconnecting if:
Expand Down Expand Up @@ -15767,7 +15815,7 @@ impl<SP: SignerProvider> Writeable for FundedChannel<SP> {
// We don't have to worry about resetting the pending `FundingNegotiation` because we
// can only read `FundingNegotiation::AwaitingSignatures` variants anyway.
let pending_splice =
self.pending_splice.as_ref().filter(|_| !self.should_reset_pending_splice_state(false));
self.pending_splice.as_ref().filter(|_| !self.should_reset_pending_splice_state(true));

let monitor_pending_tx_signatures =
self.context.monitor_pending_tx_signatures.then_some(());
Expand Down
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