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Produce FundingInfo::Contribution variants in ChannelMonitor #4498

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53569a7
Change FundingInfo::Contribution to expose contributed output scripts
wpaulino Mar 17, 2026
e07c154
Produce FundingInfo::Contribution variants in ChannelMonitor
wpaulino Mar 3, 2026
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95 changes: 76 additions & 19 deletions lightning/src/chain/channelmonitor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@ use crate::chain::package::{
use crate::chain::transaction::{OutPoint, TransactionData};
use crate::chain::{BlockLocator, WatchedOutput};
use crate::events::bump_transaction::{AnchorDescriptor, BumpTransactionEvent};
use crate::events::{ClosureReason, Event, EventHandler, ReplayEvent};
use crate::events::{ClosureReason, Event, EventHandler, FundingInfo, ReplayEvent};
use crate::ln::chan_utils::{
self, ChannelTransactionParameters, CommitmentTransaction, CounterpartyCommitmentSecrets,
HTLCClaim, HTLCOutputInCommitment, HolderCommitmentTransaction,
Expand All @@ -55,6 +55,7 @@ use crate::ln::channel_keys::{
RevocationKey,
};
use crate::ln::channelmanager::{HTLCSource, PaymentClaimDetails, SentHTLCId};
use crate::ln::funding::FundingContribution;
use crate::ln::msgs::DecodeError;
use crate::ln::types::ChannelId;
use crate::sign::{
Expand Down Expand Up @@ -688,6 +689,7 @@ pub(crate) enum ChannelMonitorUpdateStep {
channel_parameters: ChannelTransactionParameters,
holder_commitment_tx: HolderCommitmentTransaction,
counterparty_commitment_tx: CommitmentTransaction,
funding_contribution: Option<FundingContribution>,
},
RenegotiatedFundingLocked {
funding_txid: Txid,
Expand Down Expand Up @@ -773,6 +775,7 @@ impl_writeable_tlv_based_enum_upgradable!(ChannelMonitorUpdateStep,
(1, channel_parameters, (required: ReadableArgs, None)),
(3, holder_commitment_tx, required),
(5, counterparty_commitment_tx, required),
(7, funding_contribution, option),
},
(12, RenegotiatedFundingLocked) => {
(1, funding_txid, required),
Expand Down Expand Up @@ -1166,6 +1169,9 @@ struct FundingScope {
// transaction for which we have deleted claim information on some watchtowers.
current_holder_commitment_tx: HolderCommitmentTransaction,
prev_holder_commitment_tx: Option<HolderCommitmentTransaction>,

/// Our funding contribution when negotiating the corresponding funding transaction.
contribution: Option<FundingContribution>,
}

impl FundingScope {
Expand All @@ -1185,6 +1191,14 @@ impl FundingScope {
fn channel_type_features(&self) -> &ChannelTypeFeatures {
&self.channel_parameters.channel_type_features
}

fn contributed_inputs(&self) -> impl Iterator<Item = bitcoin::OutPoint> + '_ {
self.contribution.iter().flat_map(|contribution| contribution.contributed_inputs())
}

fn contributed_outputs(&self) -> impl Iterator<Item = &bitcoin::Script> + '_ {
self.contribution.iter().flat_map(|contribution| contribution.contributed_outputs())
}
}

impl_writeable_tlv_based!(FundingScope, {
Expand All @@ -1194,6 +1208,7 @@ impl_writeable_tlv_based!(FundingScope, {
(7, current_holder_commitment_tx, required),
(9, prev_holder_commitment_tx, option),
(11, counterparty_claimable_outpoints, required),
(13, contribution, option),
});

#[derive(Clone, PartialEq)]
Expand Down Expand Up @@ -1756,6 +1771,7 @@ pub(crate) fn write_chanmon_internal<Signer: EcdsaChannelSigner, W: Writer>(
(35, channel_monitor.is_manual_broadcast, required),
(37, channel_monitor.funding_seen_onchain, required),
(39, channel_monitor.best_block.previous_blocks, required),
(41, channel_monitor.funding.contribution, option),
});

Ok(())
Expand Down Expand Up @@ -1905,6 +1921,8 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitor<Signer> {

current_holder_commitment_tx: initial_holder_commitment_tx,
prev_holder_commitment_tx: None,

contribution: None,
},
pending_funding: vec![],

Expand Down Expand Up @@ -3959,6 +3977,7 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
&mut self, logger: &WithContext<L>, channel_parameters: &ChannelTransactionParameters,
alternative_holder_commitment_tx: &HolderCommitmentTransaction,
alternative_counterparty_commitment_tx: &CommitmentTransaction,
funding_contribution: &Option<FundingContribution>,
) -> Result<(), ()> {
let alternative_counterparty_commitment_txid =
alternative_counterparty_commitment_tx.trust().txid();
Expand Down Expand Up @@ -4025,6 +4044,7 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
counterparty_claimable_outpoints,
current_holder_commitment_tx: alternative_holder_commitment_tx.clone(),
prev_holder_commitment_tx: None,
contribution: funding_contribution.clone(),
};
let alternative_funding_outpoint = alternative_funding.funding_outpoint();

Expand Down Expand Up @@ -4081,6 +4101,37 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
Ok(())
}

fn queue_discard_funding_event(
&mut self, discarded_funding: impl Iterator<Item = FundingScope>,
) {
let (mut discarded_inputs, mut discarded_outputs) = (new_hash_set(), new_hash_set());
for funding in discarded_funding {
if funding.contribution.is_none() {
self.pending_events.push(Event::DiscardFunding {
channel_id: self.channel_id,
funding_info: FundingInfo::OutPoint { outpoint: funding.funding_outpoint() },
});
} else if let Some(contribution) = funding.contribution {
if let Some((inputs, outputs)) = contribution.into_unique_contributions(
self.funding.contributed_inputs(),
self.funding.contributed_outputs(),
) {
discarded_inputs.extend(inputs);
discarded_outputs.extend(outputs);
}
}
}
if !discarded_inputs.is_empty() || !discarded_outputs.is_empty() {
self.pending_events.push(Event::DiscardFunding {
channel_id: self.channel_id,
funding_info: FundingInfo::Contribution {
inputs: discarded_inputs.into_iter().collect(),
outputs: discarded_outputs.into_iter().collect(),
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},
});
Comment on lines +4125 to +4131
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@jkczyz jkczyz Apr 27, 2026

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Hmm... in channelmanager.rs, we make a separate DiscardFunding event for each attempt. Should we do the same here? It would remove the non-determinism introduced by the hash set.

}
}

fn promote_funding(&mut self, new_funding_txid: Txid) -> Result<(), ()> {
let prev_funding_txid = self.funding.funding_txid();

Expand Down Expand Up @@ -4111,18 +4162,20 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
let no_further_updates_allowed = self.no_further_updates_allowed();

// The swap above places the previous `FundingScope` into `pending_funding`.
for funding in self.pending_funding.drain(..) {
let funding_txid = funding.funding_txid();
self.outputs_to_watch.remove(&funding_txid);
if no_further_updates_allowed && funding_txid != prev_funding_txid {
self.pending_events.push(Event::DiscardFunding {
channel_id: self.channel_id,
funding_info: crate::events::FundingInfo::OutPoint {
outpoint: funding.funding_outpoint(),
},
});
}
for funding in &self.pending_funding {
self.outputs_to_watch.remove(&funding.funding_txid());
}
let mut discarded_funding = Vec::new();
mem::swap(&mut self.pending_funding, &mut discarded_funding);
let discarded_funding = discarded_funding
.into_iter()
// The previous funding is filtered out since it was already locked, so nothing needs to
// be discarded.
.filter(|funding| {
no_further_updates_allowed && funding.funding_txid() != prev_funding_txid
});
self.queue_discard_funding_event(discarded_funding);

if let Some((alternative_funding_txid, _)) = self.alternative_funding_confirmed.take() {
// In exceedingly rare cases, it's possible there was a reorg that caused a potential funding to
// be locked in that this `ChannelMonitor` has not yet seen. Thus, we avoid a runtime assertion
Expand Down Expand Up @@ -4239,11 +4292,13 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
},
ChannelMonitorUpdateStep::RenegotiatedFunding {
channel_parameters, holder_commitment_tx, counterparty_commitment_tx,
funding_contribution,
} => {
log_trace!(logger, "Updating ChannelMonitor with alternative holder and counterparty commitment transactions for funding txid {}",
channel_parameters.funding_outpoint.unwrap().txid);
if let Err(_) = self.renegotiated_funding(
logger, channel_parameters, holder_commitment_tx, counterparty_commitment_tx,
funding_contribution,
) {
ret = Err(());
}
Expand Down Expand Up @@ -5810,15 +5865,14 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
self.funding_spend_confirmed = Some(entry.txid);
self.confirmed_commitment_tx_counterparty_output = commitment_tx_to_counterparty_output;
if self.alternative_funding_confirmed.is_none() {
for funding in self.pending_funding.drain(..) {
// We saw a confirmed commitment for our currently locked funding, so
// discard all pending ones.
for funding in &self.pending_funding {
self.outputs_to_watch.remove(&funding.funding_txid());
self.pending_events.push(Event::DiscardFunding {
channel_id: self.channel_id,
funding_info: crate::events::FundingInfo::OutPoint {
outpoint: funding.funding_outpoint(),
},
});
}
let mut discarded_funding = Vec::new();
mem::swap(&mut self.pending_funding, &mut discarded_funding);
self.queue_discard_funding_event(discarded_funding.into_iter());
}
},
OnchainEvent::AlternativeFundingConfirmation {} => {
Expand Down Expand Up @@ -6696,6 +6750,7 @@ impl<'a, 'b, ES: EntropySource, SP: SignerProvider> ReadableArgs<(&'a ES, &'b SP
let mut is_manual_broadcast = RequiredWrapper(None);
let mut funding_seen_onchain = RequiredWrapper(None);
let mut best_block_previous_blocks = None;
let mut current_funding_contribution = None;
read_tlv_fields!(reader, {
(1, funding_spend_confirmed, option),
(3, htlcs_resolved_on_chain, optional_vec),
Expand All @@ -6719,6 +6774,7 @@ impl<'a, 'b, ES: EntropySource, SP: SignerProvider> ReadableArgs<(&'a ES, &'b SP
(35, is_manual_broadcast, (default_value, false)),
(37, funding_seen_onchain, (default_value, true)),
(39, best_block_previous_blocks, option), // Added and always set in 0.3
(41, current_funding_contribution, option),
});
if let Some(previous_blocks) = best_block_previous_blocks {
best_block.previous_blocks = previous_blocks;
Expand Down Expand Up @@ -6837,6 +6893,7 @@ impl<'a, 'b, ES: EntropySource, SP: SignerProvider> ReadableArgs<(&'a ES, &'b SP

current_holder_commitment_tx,
prev_holder_commitment_tx,
contribution: current_funding_contribution,
},
pending_funding: pending_funding.unwrap_or(vec![]),
is_manual_broadcast: is_manual_broadcast.0.unwrap(),
Expand Down
6 changes: 3 additions & 3 deletions lightning/src/events/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ use bitcoin::hashes::sha256::Hash as Sha256;
use bitcoin::hashes::Hash;
use bitcoin::script::ScriptBuf;
use bitcoin::secp256k1::PublicKey;
use bitcoin::{OutPoint, Transaction, TxOut};
use bitcoin::{OutPoint, Transaction};
use core::ops::Deref;

#[allow(unused_imports)]
Expand Down Expand Up @@ -81,8 +81,8 @@ pub enum FundingInfo {
Contribution {
/// UTXOs spent as inputs contributed to the funding transaction.
inputs: Vec<OutPoint>,
/// Outputs contributed to the funding transaction.
outputs: Vec<TxOut>,
/// Output scripts contributed to the funding transaction.
outputs: Vec<ScriptBuf>,
},
}

Expand Down
43 changes: 27 additions & 16 deletions lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3115,7 +3115,7 @@ impl PendingFunding {
self.contributions.iter().flat_map(|c| c.contributed_inputs())
}

fn contributed_outputs(&self) -> impl Iterator<Item = &TxOut> + '_ {
fn contributed_outputs(&self) -> impl Iterator<Item = &bitcoin::Script> + '_ {
self.contributions.iter().flat_map(|c| c.contributed_outputs())
}

Expand All @@ -3124,7 +3124,7 @@ impl PendingFunding {
self.contributions[..len.saturating_sub(1)].iter().flat_map(|c| c.contributed_inputs())
}

fn prior_contributed_outputs(&self) -> impl Iterator<Item = &TxOut> + '_ {
fn prior_contributed_outputs(&self) -> impl Iterator<Item = &bitcoin::Script> + '_ {
let len = self.contributions.len();
self.contributions[..len.saturating_sub(1)].iter().flat_map(|c| c.contributed_outputs())
}
Expand Down Expand Up @@ -3173,7 +3173,7 @@ pub(crate) enum QuiescentAction {

pub(super) enum QuiescentError {
DoNothing,
DiscardFunding { inputs: Vec<bitcoin::OutPoint>, outputs: Vec<bitcoin::TxOut> },
DiscardFunding { inputs: Vec<bitcoin::OutPoint>, outputs: Vec<ScriptBuf> },
FailSplice(SpliceFundingFailed),
}

Expand Down Expand Up @@ -6850,23 +6850,27 @@ impl FundingNegotiationContext {
}
}

fn into_contributed_inputs_and_outputs(self) -> (Vec<bitcoin::OutPoint>, Vec<TxOut>) {
fn into_contributed_inputs_and_outputs(self) -> (Vec<bitcoin::OutPoint>, Vec<ScriptBuf>) {
let contributed_inputs =
self.our_funding_inputs.into_iter().map(|input| input.utxo.outpoint).collect();
let contributed_outputs = self.our_funding_outputs;
let contributed_outputs =
self.our_funding_outputs.into_iter().map(|output| output.script_pubkey).collect();
(contributed_inputs, contributed_outputs)
}

fn contributed_inputs(&self) -> impl Iterator<Item = bitcoin::OutPoint> + '_ {
self.our_funding_inputs.iter().map(|input| input.utxo.outpoint)
}

fn contributed_outputs(&self) -> impl Iterator<Item = &TxOut> + '_ {
self.our_funding_outputs.iter()
fn contributed_outputs(&self) -> impl Iterator<Item = &bitcoin::Script> + '_ {
self.our_funding_outputs.iter().map(|output| output.script_pubkey.as_script())
}

fn to_contributed_inputs_and_outputs(&self) -> (Vec<bitcoin::OutPoint>, Vec<TxOut>) {
(self.contributed_inputs().collect(), self.contributed_outputs().cloned().collect())
fn to_contributed_inputs_and_outputs(&self) -> (Vec<bitcoin::OutPoint>, Vec<ScriptBuf>) {
(
self.contributed_inputs().collect(),
self.contributed_outputs().map(|script| script.into()).collect(),
)
}
}

Expand Down Expand Up @@ -7027,8 +7031,8 @@ pub struct SpliceFundingFailed {
/// UTXOs spent as inputs contributed to the splice transaction.
pub contributed_inputs: Vec<bitcoin::OutPoint>,

/// Outputs contributed to the splice transaction.
pub contributed_outputs: Vec<bitcoin::TxOut>,
/// Output scripts contributed to the splice transaction.
pub contributed_outputs: Vec<ScriptBuf>,
}

macro_rules! maybe_create_splice_funding_failed {
Expand Down Expand Up @@ -7068,7 +7072,7 @@ macro_rules! maybe_create_splice_funding_failed {
contributed_inputs.retain(|i| *i != input);
}
for output in pending_splice.prior_contributed_outputs() {
contributed_outputs.retain(|o| o.script_pubkey != output.script_pubkey);
contributed_outputs.retain(|i| i != output);
}
}

Expand Down Expand Up @@ -7119,7 +7123,7 @@ where
inputs.retain(|i| *i != input);
}
for output in pending_splice.contributed_outputs() {
outputs.retain(|o| o.script_pubkey != output.script_pubkey);
outputs.retain(|o| o.as_script() != output);
}
}
SpliceFundingFailed {
Expand Down Expand Up @@ -8314,12 +8318,12 @@ where
&mut self, msg: &msgs::CommitmentSigned, fee_estimator: &LowerBoundedFeeEstimator<F>,
logger: &L,
) -> Result<Option<ChannelMonitorUpdate>, ChannelError> {
debug_assert!(self
let signing_session = self
.context
.interactive_tx_signing_session
.as_ref()
.map(|signing_session| !signing_session.has_received_tx_signatures())
.unwrap_or(false));
.expect("Signing session must exist for negotiated pending splice");
debug_assert!(!signing_session.has_received_tx_signatures());
Comment on lines +8321 to +8326
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@ldk-claude-review-bot ldk-claude-review-bot Apr 27, 2026

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Nit: This changes from a debug_assert (no-op in release builds) to expect (panics in release builds). The old code combined the existence check and state check into a single debug assertion; now existence is enforced unconditionally while the state check remains debug-only.

This is arguably safer (fail-fast instead of silent invariant violation), but since signing_session isn't used beyond the debug_assert on the next line, consider whether returning a ChannelError would be more robust than panicking — consistent with how this function handles other missing state (e.g., the commitment_point error path at line 8340).


let pending_splice_funding = self
.pending_splice
Expand Down Expand Up @@ -8371,6 +8375,12 @@ where
);
}

let funding_contribution = self
.pending_splice
.as_ref()
.and_then(|pending_splice| pending_splice.contributions.last())
.cloned();

log_info!(
logger,
"Received splice initial commitment_signed from peer with funding txid {}",
Expand All @@ -8384,6 +8394,7 @@ where
channel_parameters: pending_splice_funding.channel_transaction_parameters.clone(),
holder_commitment_tx,
counterparty_commitment_tx,
funding_contribution,
}],
channel_id: Some(self.context.channel_id()),
};
Expand Down
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