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Move commitment_signed_check to ChannelContext
Now that commitment_signed is split into check and accept methods, move the check portion from FundedChannel to ChannelContext. This allows calling it with a different FundingScope when there are pending splices and RBF attempts.
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‎lightning/src/ln/channel.rs‎

Lines changed: 128 additions & 124 deletions
Original file line numberDiff line numberDiff line change
@@ -3451,6 +3451,132 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
34513451
!matches!(self.channel_state, ChannelState::AwaitingChannelReady(flags) if flags.is_set(AwaitingChannelReadyFlags::WAITING_FOR_BATCH))
34523452
}
34533453

3454+
fn validate_commitment_signed<L: Deref>(
3455+
&self, funding: &FundingScope, holder_commitment_point: &HolderCommitmentPoint,
3456+
msg: &msgs::CommitmentSigned, logger: &L,
3457+
) -> Result<LatestHolderCommitmentTXInfo, ChannelError>
3458+
where
3459+
L::Target: Logger,
3460+
{
3461+
let funding_script = funding.get_funding_redeemscript();
3462+
3463+
let keys = self.build_holder_transaction_keys(funding, holder_commitment_point.current_point());
3464+
3465+
let commitment_stats = self.build_commitment_transaction(funding, holder_commitment_point.transaction_number(), &keys, true, false, logger);
3466+
let commitment_txid = {
3467+
let trusted_tx = commitment_stats.tx.trust();
3468+
let bitcoin_tx = trusted_tx.built_transaction();
3469+
let sighash = bitcoin_tx.get_sighash_all(&funding_script, funding.get_value_satoshis());
3470+
3471+
log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
3472+
log_bytes!(msg.signature.serialize_compact()[..]),
3473+
log_bytes!(funding.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
3474+
log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), &self.channel_id());
3475+
if let Err(_) = self.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &funding.counterparty_funding_pubkey()) {
3476+
return Err(ChannelError::close("Invalid commitment tx signature from peer".to_owned()));
3477+
}
3478+
bitcoin_tx.txid
3479+
};
3480+
let mut htlcs_cloned: Vec<_> = commitment_stats.htlcs_included.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
3481+
3482+
// If our counterparty updated the channel fee in this commitment transaction, check that
3483+
// they can actually afford the new fee now.
3484+
let update_fee = if let Some((_, update_state)) = self.pending_update_fee {
3485+
update_state == FeeUpdateState::RemoteAnnounced
3486+
} else { false };
3487+
if update_fee {
3488+
debug_assert!(!funding.is_outbound());
3489+
let counterparty_reserve_we_require_msat = funding.holder_selected_channel_reserve_satoshis * 1000;
3490+
if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
3491+
return Err(ChannelError::close("Funding remote cannot afford proposed new fee".to_owned()));
3492+
}
3493+
}
3494+
#[cfg(any(test, fuzzing))]
3495+
{
3496+
if funding.is_outbound() {
3497+
let projected_commit_tx_info = funding.next_local_commitment_tx_fee_info_cached.lock().unwrap().take();
3498+
*funding.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
3499+
if let Some(info) = projected_commit_tx_info {
3500+
let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len()
3501+
+ self.holding_cell_htlc_updates.len();
3502+
if info.total_pending_htlcs == total_pending_htlcs
3503+
&& info.next_holder_htlc_id == self.next_holder_htlc_id
3504+
&& info.next_counterparty_htlc_id == self.next_counterparty_htlc_id
3505+
&& info.feerate == self.feerate_per_kw {
3506+
assert_eq!(commitment_stats.total_fee_sat, info.fee / 1000);
3507+
}
3508+
}
3509+
}
3510+
}
3511+
3512+
if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
3513+
return Err(ChannelError::close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), commitment_stats.num_nondust_htlcs)));
3514+
}
3515+
3516+
// Up to LDK 0.0.115, HTLC information was required to be duplicated in the
3517+
// `htlcs_and_sigs` vec and in the `holder_commitment_tx` itself, both of which were passed
3518+
// in the `ChannelMonitorUpdate`. In 0.0.115, support for having a separate set of
3519+
// outbound-non-dust-HTLCSources in the `ChannelMonitorUpdate` was added, however for
3520+
// backwards compatibility, we never use it in production. To provide test coverage, here,
3521+
// we randomly decide (in test/fuzzing builds) to use the new vec sometimes.
3522+
#[allow(unused_assignments, unused_mut)]
3523+
let mut separate_nondust_htlc_sources = false;
3524+
#[cfg(all(feature = "std", any(test, fuzzing)))] {
3525+
use core::hash::{BuildHasher, Hasher};
3526+
// Get a random value using the only std API to do so - the DefaultHasher
3527+
let rand_val = std::collections::hash_map::RandomState::new().build_hasher().finish();
3528+
separate_nondust_htlc_sources = rand_val % 2 == 0;
3529+
}
3530+
3531+
let mut nondust_htlc_sources = Vec::with_capacity(htlcs_cloned.len());
3532+
let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
3533+
for (idx, (htlc, mut source_opt)) in htlcs_cloned.drain(..).enumerate() {
3534+
if let Some(_) = htlc.transaction_output_index {
3535+
let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
3536+
funding.get_counterparty_selected_contest_delay().unwrap(), &htlc, &self.channel_type,
3537+
&keys.broadcaster_delayed_payment_key, &keys.revocation_key);
3538+
3539+
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &self.channel_type, &keys);
3540+
let htlc_sighashtype = if self.channel_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
3541+
let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).p2wsh_signature_hash(0, &htlc_redeemscript, htlc.to_bitcoin_amount(), htlc_sighashtype).unwrap()[..]);
3542+
log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}.",
3543+
log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.to_public_key().serialize()),
3544+
encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), &self.channel_id());
3545+
if let Err(_) = self.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key.to_public_key()) {
3546+
return Err(ChannelError::close("Invalid HTLC tx signature from peer".to_owned()));
3547+
}
3548+
if !separate_nondust_htlc_sources {
3549+
htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
3550+
}
3551+
} else {
3552+
htlcs_and_sigs.push((htlc, None, source_opt.take()));
3553+
}
3554+
if separate_nondust_htlc_sources {
3555+
if let Some(source) = source_opt.take() {
3556+
nondust_htlc_sources.push(source);
3557+
}
3558+
}
3559+
debug_assert!(source_opt.is_none(), "HTLCSource should have been put somewhere");
3560+
}
3561+
3562+
let holder_commitment_tx = HolderCommitmentTransaction::new(
3563+
commitment_stats.tx,
3564+
msg.signature,
3565+
msg.htlc_signatures.clone(),
3566+
&funding.get_holder_pubkeys().funding_pubkey,
3567+
funding.counterparty_funding_pubkey()
3568+
);
3569+
3570+
self.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, commitment_stats.outbound_htlc_preimages)
3571+
.map_err(|_| ChannelError::close("Failed to validate our commitment".to_owned()))?;
3572+
3573+
Ok(LatestHolderCommitmentTXInfo {
3574+
commitment_tx: holder_commitment_tx,
3575+
htlc_outputs: htlcs_and_sigs,
3576+
nondust_htlc_sources,
3577+
})
3578+
}
3579+
34543580
/// Transaction nomenclature is somewhat confusing here as there are many different cases - a
34553581
/// transaction is referred to as "a's transaction" implying that a will be able to broadcast
34563582
/// the transaction. Thus, b will generally be sending a signature over such a transaction to
@@ -4706,7 +4832,7 @@ struct CommitmentTxInfoCached {
47064832
}
47074833

47084834
/// Partial data from ChannelMonitorUpdateStep::LatestHolderCommitmentTXInfo used to simplify the
4709-
/// return type of `FundedChannel::validate_commitment_signed`.
4835+
/// return type of `ChannelContext::validate_commitment_signed`.
47104836
struct LatestHolderCommitmentTXInfo {
47114837
pub commitment_tx: HolderCommitmentTransaction,
47124838
pub htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Signature>, Option<HTLCSource>)>,
@@ -5501,128 +5627,6 @@ impl<SP: Deref> FundedChannel<SP> where
55015627
Ok(channel_monitor)
55025628
}
55035629

5504-
fn validate_commitment_signed<L: Deref>(&self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<LatestHolderCommitmentTXInfo, ChannelError>
5505-
where L::Target: Logger
5506-
{
5507-
let funding_script = self.funding.get_funding_redeemscript();
5508-
5509-
let keys = self.context.build_holder_transaction_keys(&self.funding, self.holder_commitment_point.current_point());
5510-
5511-
let commitment_stats = self.context.build_commitment_transaction(&self.funding, self.holder_commitment_point.transaction_number(), &keys, true, false, logger);
5512-
let commitment_txid = {
5513-
let trusted_tx = commitment_stats.tx.trust();
5514-
let bitcoin_tx = trusted_tx.built_transaction();
5515-
let sighash = bitcoin_tx.get_sighash_all(&funding_script, self.funding.get_value_satoshis());
5516-
5517-
log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
5518-
log_bytes!(msg.signature.serialize_compact()[..]),
5519-
log_bytes!(self.funding.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
5520-
log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), &self.context.channel_id());
5521-
if let Err(_) = self.context.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &self.funding.counterparty_funding_pubkey()) {
5522-
return Err(ChannelError::close("Invalid commitment tx signature from peer".to_owned()));
5523-
}
5524-
bitcoin_tx.txid
5525-
};
5526-
let mut htlcs_cloned: Vec<_> = commitment_stats.htlcs_included.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
5527-
5528-
// If our counterparty updated the channel fee in this commitment transaction, check that
5529-
// they can actually afford the new fee now.
5530-
let update_fee = if let Some((_, update_state)) = self.context.pending_update_fee {
5531-
update_state == FeeUpdateState::RemoteAnnounced
5532-
} else { false };
5533-
if update_fee {
5534-
debug_assert!(!self.funding.is_outbound());
5535-
let counterparty_reserve_we_require_msat = self.funding.holder_selected_channel_reserve_satoshis * 1000;
5536-
if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
5537-
return Err(ChannelError::close("Funding remote cannot afford proposed new fee".to_owned()));
5538-
}
5539-
}
5540-
#[cfg(any(test, fuzzing))]
5541-
{
5542-
if self.funding.is_outbound() {
5543-
let projected_commit_tx_info = self.funding.next_local_commitment_tx_fee_info_cached.lock().unwrap().take();
5544-
*self.funding.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
5545-
if let Some(info) = projected_commit_tx_info {
5546-
let total_pending_htlcs = self.context.pending_inbound_htlcs.len() + self.context.pending_outbound_htlcs.len()
5547-
+ self.context.holding_cell_htlc_updates.len();
5548-
if info.total_pending_htlcs == total_pending_htlcs
5549-
&& info.next_holder_htlc_id == self.context.next_holder_htlc_id
5550-
&& info.next_counterparty_htlc_id == self.context.next_counterparty_htlc_id
5551-
&& info.feerate == self.context.feerate_per_kw {
5552-
assert_eq!(commitment_stats.total_fee_sat, info.fee / 1000);
5553-
}
5554-
}
5555-
}
5556-
}
5557-
5558-
if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
5559-
return Err(ChannelError::close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), commitment_stats.num_nondust_htlcs)));
5560-
}
5561-
5562-
// Up to LDK 0.0.115, HTLC information was required to be duplicated in the
5563-
// `htlcs_and_sigs` vec and in the `holder_commitment_tx` itself, both of which were passed
5564-
// in the `ChannelMonitorUpdate`. In 0.0.115, support for having a separate set of
5565-
// outbound-non-dust-HTLCSources in the `ChannelMonitorUpdate` was added, however for
5566-
// backwards compatibility, we never use it in production. To provide test coverage, here,
5567-
// we randomly decide (in test/fuzzing builds) to use the new vec sometimes.
5568-
#[allow(unused_assignments, unused_mut)]
5569-
let mut separate_nondust_htlc_sources = false;
5570-
#[cfg(all(feature = "std", any(test, fuzzing)))] {
5571-
use core::hash::{BuildHasher, Hasher};
5572-
// Get a random value using the only std API to do so - the DefaultHasher
5573-
let rand_val = std::collections::hash_map::RandomState::new().build_hasher().finish();
5574-
separate_nondust_htlc_sources = rand_val % 2 == 0;
5575-
}
5576-
5577-
let mut nondust_htlc_sources = Vec::with_capacity(htlcs_cloned.len());
5578-
let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
5579-
for (idx, (htlc, mut source_opt)) in htlcs_cloned.drain(..).enumerate() {
5580-
if let Some(_) = htlc.transaction_output_index {
5581-
let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
5582-
self.funding.get_counterparty_selected_contest_delay().unwrap(), &htlc, &self.context.channel_type,
5583-
&keys.broadcaster_delayed_payment_key, &keys.revocation_key);
5584-
5585-
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &self.context.channel_type, &keys);
5586-
let htlc_sighashtype = if self.context.channel_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
5587-
let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).p2wsh_signature_hash(0, &htlc_redeemscript, htlc.to_bitcoin_amount(), htlc_sighashtype).unwrap()[..]);
5588-
log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}.",
5589-
log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.to_public_key().serialize()),
5590-
encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), &self.context.channel_id());
5591-
if let Err(_) = self.context.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key.to_public_key()) {
5592-
return Err(ChannelError::close("Invalid HTLC tx signature from peer".to_owned()));
5593-
}
5594-
if !separate_nondust_htlc_sources {
5595-
htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
5596-
}
5597-
} else {
5598-
htlcs_and_sigs.push((htlc, None, source_opt.take()));
5599-
}
5600-
if separate_nondust_htlc_sources {
5601-
if let Some(source) = source_opt.take() {
5602-
nondust_htlc_sources.push(source);
5603-
}
5604-
}
5605-
debug_assert!(source_opt.is_none(), "HTLCSource should have been put somewhere");
5606-
}
5607-
5608-
let holder_commitment_tx = HolderCommitmentTransaction::new(
5609-
commitment_stats.tx,
5610-
msg.signature,
5611-
msg.htlc_signatures.clone(),
5612-
&self.funding.get_holder_pubkeys().funding_pubkey,
5613-
self.funding.counterparty_funding_pubkey()
5614-
);
5615-
5616-
self.context.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, commitment_stats.outbound_htlc_preimages)
5617-
.map_err(|_| ChannelError::close("Failed to validate our commitment".to_owned()))?;
5618-
5619-
Ok(LatestHolderCommitmentTXInfo {
5620-
commitment_tx: holder_commitment_tx,
5621-
htlc_outputs: htlcs_and_sigs,
5622-
nondust_htlc_sources,
5623-
})
5624-
}
5625-
56265630
pub fn commitment_signed<L: Deref>(&mut self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<Option<ChannelMonitorUpdate>, ChannelError>
56275631
where L::Target: Logger
56285632
{
@@ -5639,7 +5643,7 @@ impl<SP: Deref> FundedChannel<SP> where
56395643
return Err(ChannelError::close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned()));
56405644
}
56415645

5642-
let commitment_tx_info = self.validate_commitment_signed(msg, logger)?;
5646+
let commitment_tx_info = self.context.validate_commitment_signed(&self.funding, &self.holder_commitment_point, msg, logger)?;
56435647

56445648
// Update state now that we've passed all the can-fail calls...
56455649
let mut need_commitment = false;

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