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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
@@ -3453,6 +3453,132 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
34533453
!matches!(self.channel_state, ChannelState::AwaitingChannelReady(flags) if flags.is_set(AwaitingChannelReadyFlags::WAITING_FOR_BATCH))
34543454
}
34553455

3456+
fn validate_commitment_signed<L: Deref>(
3457+
&self, funding: &FundingScope, holder_commitment_point: &HolderCommitmentPoint,
3458+
msg: &msgs::CommitmentSigned, logger: &L,
3459+
) -> Result<LatestHolderCommitmentTXInfo, ChannelError>
3460+
where
3461+
L::Target: Logger,
3462+
{
3463+
let funding_script = funding.get_funding_redeemscript();
3464+
3465+
let keys = self.build_holder_transaction_keys(funding, holder_commitment_point.current_point());
3466+
3467+
let commitment_stats = self.build_commitment_transaction(funding, holder_commitment_point.transaction_number(), &keys, true, false, logger);
3468+
let commitment_txid = {
3469+
let trusted_tx = commitment_stats.tx.trust();
3470+
let bitcoin_tx = trusted_tx.built_transaction();
3471+
let sighash = bitcoin_tx.get_sighash_all(&funding_script, funding.get_value_satoshis());
3472+
3473+
log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
3474+
log_bytes!(msg.signature.serialize_compact()[..]),
3475+
log_bytes!(funding.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
3476+
log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), &self.channel_id());
3477+
if let Err(_) = self.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &funding.counterparty_funding_pubkey()) {
3478+
return Err(ChannelError::close("Invalid commitment tx signature from peer".to_owned()));
3479+
}
3480+
bitcoin_tx.txid
3481+
};
3482+
let mut htlcs_cloned: Vec<_> = commitment_stats.htlcs_included.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
3483+
3484+
// If our counterparty updated the channel fee in this commitment transaction, check that
3485+
// they can actually afford the new fee now.
3486+
let update_fee = if let Some((_, update_state)) = self.pending_update_fee {
3487+
update_state == FeeUpdateState::RemoteAnnounced
3488+
} else { false };
3489+
if update_fee {
3490+
debug_assert!(!funding.is_outbound());
3491+
let counterparty_reserve_we_require_msat = funding.holder_selected_channel_reserve_satoshis * 1000;
3492+
if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
3493+
return Err(ChannelError::close("Funding remote cannot afford proposed new fee".to_owned()));
3494+
}
3495+
}
3496+
#[cfg(any(test, fuzzing))]
3497+
{
3498+
if funding.is_outbound() {
3499+
let projected_commit_tx_info = funding.next_local_commitment_tx_fee_info_cached.lock().unwrap().take();
3500+
*funding.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
3501+
if let Some(info) = projected_commit_tx_info {
3502+
let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len()
3503+
+ self.holding_cell_htlc_updates.len();
3504+
if info.total_pending_htlcs == total_pending_htlcs
3505+
&& info.next_holder_htlc_id == self.next_holder_htlc_id
3506+
&& info.next_counterparty_htlc_id == self.next_counterparty_htlc_id
3507+
&& info.feerate == self.feerate_per_kw {
3508+
assert_eq!(commitment_stats.total_fee_sat, info.fee / 1000);
3509+
}
3510+
}
3511+
}
3512+
}
3513+
3514+
if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
3515+
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)));
3516+
}
3517+
3518+
// Up to LDK 0.0.115, HTLC information was required to be duplicated in the
3519+
// `htlcs_and_sigs` vec and in the `holder_commitment_tx` itself, both of which were passed
3520+
// in the `ChannelMonitorUpdate`. In 0.0.115, support for having a separate set of
3521+
// outbound-non-dust-HTLCSources in the `ChannelMonitorUpdate` was added, however for
3522+
// backwards compatibility, we never use it in production. To provide test coverage, here,
3523+
// we randomly decide (in test/fuzzing builds) to use the new vec sometimes.
3524+
#[allow(unused_assignments, unused_mut)]
3525+
let mut separate_nondust_htlc_sources = false;
3526+
#[cfg(all(feature = "std", any(test, fuzzing)))] {
3527+
use core::hash::{BuildHasher, Hasher};
3528+
// Get a random value using the only std API to do so - the DefaultHasher
3529+
let rand_val = std::collections::hash_map::RandomState::new().build_hasher().finish();
3530+
separate_nondust_htlc_sources = rand_val % 2 == 0;
3531+
}
3532+
3533+
let mut nondust_htlc_sources = Vec::with_capacity(htlcs_cloned.len());
3534+
let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
3535+
for (idx, (htlc, mut source_opt)) in htlcs_cloned.drain(..).enumerate() {
3536+
if let Some(_) = htlc.transaction_output_index {
3537+
let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
3538+
funding.get_counterparty_selected_contest_delay().unwrap(), &htlc, &self.channel_type,
3539+
&keys.broadcaster_delayed_payment_key, &keys.revocation_key);
3540+
3541+
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &self.channel_type, &keys);
3542+
let htlc_sighashtype = if self.channel_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
3543+
let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).p2wsh_signature_hash(0, &htlc_redeemscript, htlc.to_bitcoin_amount(), htlc_sighashtype).unwrap()[..]);
3544+
log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}.",
3545+
log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.to_public_key().serialize()),
3546+
encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), &self.channel_id());
3547+
if let Err(_) = self.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key.to_public_key()) {
3548+
return Err(ChannelError::close("Invalid HTLC tx signature from peer".to_owned()));
3549+
}
3550+
if !separate_nondust_htlc_sources {
3551+
htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
3552+
}
3553+
} else {
3554+
htlcs_and_sigs.push((htlc, None, source_opt.take()));
3555+
}
3556+
if separate_nondust_htlc_sources {
3557+
if let Some(source) = source_opt.take() {
3558+
nondust_htlc_sources.push(source);
3559+
}
3560+
}
3561+
debug_assert!(source_opt.is_none(), "HTLCSource should have been put somewhere");
3562+
}
3563+
3564+
let holder_commitment_tx = HolderCommitmentTransaction::new(
3565+
commitment_stats.tx,
3566+
msg.signature,
3567+
msg.htlc_signatures.clone(),
3568+
&funding.get_holder_pubkeys().funding_pubkey,
3569+
funding.counterparty_funding_pubkey()
3570+
);
3571+
3572+
self.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, commitment_stats.outbound_htlc_preimages)
3573+
.map_err(|_| ChannelError::close("Failed to validate our commitment".to_owned()))?;
3574+
3575+
Ok(LatestHolderCommitmentTXInfo {
3576+
commitment_tx: holder_commitment_tx,
3577+
htlc_outputs: htlcs_and_sigs,
3578+
nondust_htlc_sources,
3579+
})
3580+
}
3581+
34563582
/// Transaction nomenclature is somewhat confusing here as there are many different cases - a
34573583
/// transaction is referred to as "a's transaction" implying that a will be able to broadcast
34583584
/// the transaction. Thus, b will generally be sending a signature over such a transaction to
@@ -4708,7 +4834,7 @@ struct CommitmentTxInfoCached {
47084834
}
47094835

47104836
/// Partial data from ChannelMonitorUpdateStep::LatestHolderCommitmentTXInfo used to simplify the
4711-
/// return type of `FundedChannel::validate_commitment_signed`.
4837+
/// return type of `ChannelContext::validate_commitment_signed`.
47124838
struct LatestHolderCommitmentTXInfo {
47134839
pub commitment_tx: HolderCommitmentTransaction,
47144840
pub htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Signature>, Option<HTLCSource>)>,
@@ -5503,128 +5629,6 @@ impl<SP: Deref> FundedChannel<SP> where
55035629
Ok(channel_monitor)
55045630
}
55055631

5506-
fn validate_commitment_signed<L: Deref>(&self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<LatestHolderCommitmentTXInfo, ChannelError>
5507-
where L::Target: Logger
5508-
{
5509-
let funding_script = self.funding.get_funding_redeemscript();
5510-
5511-
let keys = self.context.build_holder_transaction_keys(&self.funding, self.holder_commitment_point.current_point());
5512-
5513-
let commitment_stats = self.context.build_commitment_transaction(&self.funding, self.holder_commitment_point.transaction_number(), &keys, true, false, logger);
5514-
let commitment_txid = {
5515-
let trusted_tx = commitment_stats.tx.trust();
5516-
let bitcoin_tx = trusted_tx.built_transaction();
5517-
let sighash = bitcoin_tx.get_sighash_all(&funding_script, self.funding.get_value_satoshis());
5518-
5519-
log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
5520-
log_bytes!(msg.signature.serialize_compact()[..]),
5521-
log_bytes!(self.funding.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
5522-
log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), &self.context.channel_id());
5523-
if let Err(_) = self.context.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &self.funding.counterparty_funding_pubkey()) {
5524-
return Err(ChannelError::close("Invalid commitment tx signature from peer".to_owned()));
5525-
}
5526-
bitcoin_tx.txid
5527-
};
5528-
let mut htlcs_cloned: Vec<_> = commitment_stats.htlcs_included.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
5529-
5530-
// If our counterparty updated the channel fee in this commitment transaction, check that
5531-
// they can actually afford the new fee now.
5532-
let update_fee = if let Some((_, update_state)) = self.context.pending_update_fee {
5533-
update_state == FeeUpdateState::RemoteAnnounced
5534-
} else { false };
5535-
if update_fee {
5536-
debug_assert!(!self.funding.is_outbound());
5537-
let counterparty_reserve_we_require_msat = self.funding.holder_selected_channel_reserve_satoshis * 1000;
5538-
if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
5539-
return Err(ChannelError::close("Funding remote cannot afford proposed new fee".to_owned()));
5540-
}
5541-
}
5542-
#[cfg(any(test, fuzzing))]
5543-
{
5544-
if self.funding.is_outbound() {
5545-
let projected_commit_tx_info = self.funding.next_local_commitment_tx_fee_info_cached.lock().unwrap().take();
5546-
*self.funding.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
5547-
if let Some(info) = projected_commit_tx_info {
5548-
let total_pending_htlcs = self.context.pending_inbound_htlcs.len() + self.context.pending_outbound_htlcs.len()
5549-
+ self.context.holding_cell_htlc_updates.len();
5550-
if info.total_pending_htlcs == total_pending_htlcs
5551-
&& info.next_holder_htlc_id == self.context.next_holder_htlc_id
5552-
&& info.next_counterparty_htlc_id == self.context.next_counterparty_htlc_id
5553-
&& info.feerate == self.context.feerate_per_kw {
5554-
assert_eq!(commitment_stats.total_fee_sat, info.fee / 1000);
5555-
}
5556-
}
5557-
}
5558-
}
5559-
5560-
if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
5561-
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)));
5562-
}
5563-
5564-
// Up to LDK 0.0.115, HTLC information was required to be duplicated in the
5565-
// `htlcs_and_sigs` vec and in the `holder_commitment_tx` itself, both of which were passed
5566-
// in the `ChannelMonitorUpdate`. In 0.0.115, support for having a separate set of
5567-
// outbound-non-dust-HTLCSources in the `ChannelMonitorUpdate` was added, however for
5568-
// backwards compatibility, we never use it in production. To provide test coverage, here,
5569-
// we randomly decide (in test/fuzzing builds) to use the new vec sometimes.
5570-
#[allow(unused_assignments, unused_mut)]
5571-
let mut separate_nondust_htlc_sources = false;
5572-
#[cfg(all(feature = "std", any(test, fuzzing)))] {
5573-
use core::hash::{BuildHasher, Hasher};
5574-
// Get a random value using the only std API to do so - the DefaultHasher
5575-
let rand_val = std::collections::hash_map::RandomState::new().build_hasher().finish();
5576-
separate_nondust_htlc_sources = rand_val % 2 == 0;
5577-
}
5578-
5579-
let mut nondust_htlc_sources = Vec::with_capacity(htlcs_cloned.len());
5580-
let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
5581-
for (idx, (htlc, mut source_opt)) in htlcs_cloned.drain(..).enumerate() {
5582-
if let Some(_) = htlc.transaction_output_index {
5583-
let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
5584-
self.funding.get_counterparty_selected_contest_delay().unwrap(), &htlc, &self.context.channel_type,
5585-
&keys.broadcaster_delayed_payment_key, &keys.revocation_key);
5586-
5587-
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &self.context.channel_type, &keys);
5588-
let htlc_sighashtype = if self.context.channel_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
5589-
let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).p2wsh_signature_hash(0, &htlc_redeemscript, htlc.to_bitcoin_amount(), htlc_sighashtype).unwrap()[..]);
5590-
log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}.",
5591-
log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.to_public_key().serialize()),
5592-
encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), &self.context.channel_id());
5593-
if let Err(_) = self.context.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key.to_public_key()) {
5594-
return Err(ChannelError::close("Invalid HTLC tx signature from peer".to_owned()));
5595-
}
5596-
if !separate_nondust_htlc_sources {
5597-
htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
5598-
}
5599-
} else {
5600-
htlcs_and_sigs.push((htlc, None, source_opt.take()));
5601-
}
5602-
if separate_nondust_htlc_sources {
5603-
if let Some(source) = source_opt.take() {
5604-
nondust_htlc_sources.push(source);
5605-
}
5606-
}
5607-
debug_assert!(source_opt.is_none(), "HTLCSource should have been put somewhere");
5608-
}
5609-
5610-
let holder_commitment_tx = HolderCommitmentTransaction::new(
5611-
commitment_stats.tx,
5612-
msg.signature,
5613-
msg.htlc_signatures.clone(),
5614-
&self.funding.get_holder_pubkeys().funding_pubkey,
5615-
self.funding.counterparty_funding_pubkey()
5616-
);
5617-
5618-
self.context.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, commitment_stats.outbound_htlc_preimages)
5619-
.map_err(|_| ChannelError::close("Failed to validate our commitment".to_owned()))?;
5620-
5621-
Ok(LatestHolderCommitmentTXInfo {
5622-
commitment_tx: holder_commitment_tx,
5623-
htlc_outputs: htlcs_and_sigs,
5624-
nondust_htlc_sources,
5625-
})
5626-
}
5627-
56285632
pub fn commitment_signed<L: Deref>(&mut self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<Option<ChannelMonitorUpdate>, ChannelError>
56295633
where L::Target: Logger
56305634
{
@@ -5641,7 +5645,7 @@ impl<SP: Deref> FundedChannel<SP> where
56415645
return Err(ChannelError::close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned()));
56425646
}
56435647

5644-
let commitment_tx_info = self.validate_commitment_signed(msg, logger)?;
5648+
let commitment_tx_info = self.context.validate_commitment_signed(&self.funding, &self.holder_commitment_point, msg, logger)?;
56455649

56465650
// Update state now that we've passed all the can-fail calls...
56475651
let mut need_commitment = false;

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