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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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2 files changed

+142
-138
lines changed

2 files changed

+142
-138
lines changed

‎lightning/src/chain/channelmonitor.rs‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -530,9 +530,9 @@ impl_writeable_tlv_based_enum_upgradable!(OnchainEvent,
530530
);
531531

532532
/// Partial data from ChannelMonitorUpdateStep::LatestHolderCommitmentTXInfo used to simplify the
533-
/// return type of [`FundedChannel::commitment_signed_check`].
533+
/// return type of [`ChannelContext::commitment_signed_check`].
534534
///
535-
/// [`FundedChannel::commitment_signed_check`]: crate::ln::channel::FundedChannel::commitment_signed_check
535+
/// [`ChannelContext::commitment_signed_check`]: crate::ln::channel::ChannelContext::commitment_signed_check
536536
pub(crate) struct LatestHolderCommitmentTXInfo {
537537
pub commitment_tx: HolderCommitmentTransaction,
538538
pub htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Signature>, Option<HTLCSource>)>,

‎lightning/src/ln/channel.rs‎

Lines changed: 140 additions & 136 deletions
Original file line numberDiff line numberDiff line change
@@ -3452,6 +3452,145 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
34523452
!matches!(self.channel_state, ChannelState::AwaitingChannelReady(flags) if flags.is_set(AwaitingChannelReadyFlags::WAITING_FOR_BATCH))
34533453
}
34543454

3455+
fn commitment_signed_check<L: Deref>(
3456+
&self, funding: &FundingScope, holder_commitment_point: &HolderCommitmentPoint,
3457+
msg: &msgs::CommitmentSigned, logger: &L,
3458+
) -> Result<LatestHolderCommitmentTXInfo, ChannelError>
3459+
where
3460+
L::Target: Logger,
3461+
{
3462+
if self.channel_state.is_quiescent() {
3463+
return Err(ChannelError::WarnAndDisconnect("Got commitment_signed message while quiescent".to_owned()));
3464+
}
3465+
if !matches!(self.channel_state, ChannelState::ChannelReady(_)) {
3466+
return Err(ChannelError::close("Got commitment signed message when channel was not in an operational state".to_owned()));
3467+
}
3468+
if self.channel_state.is_peer_disconnected() {
3469+
return Err(ChannelError::close("Peer sent commitment_signed when we needed a channel_reestablish".to_owned()));
3470+
}
3471+
if self.channel_state.is_both_sides_shutdown() && self.last_sent_closing_fee.is_some() {
3472+
return Err(ChannelError::close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned()));
3473+
}
3474+
3475+
let funding_script = funding.get_funding_redeemscript();
3476+
3477+
let keys = self.build_holder_transaction_keys(funding, holder_commitment_point.current_point());
3478+
3479+
let commitment_stats = self.build_commitment_transaction(funding, holder_commitment_point.transaction_number(), &keys, true, false, logger);
3480+
let commitment_txid = {
3481+
let trusted_tx = commitment_stats.tx.trust();
3482+
let bitcoin_tx = trusted_tx.built_transaction();
3483+
let sighash = bitcoin_tx.get_sighash_all(&funding_script, funding.get_value_satoshis());
3484+
3485+
log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
3486+
log_bytes!(msg.signature.serialize_compact()[..]),
3487+
log_bytes!(funding.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
3488+
log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), &self.channel_id());
3489+
if let Err(_) = self.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &funding.counterparty_funding_pubkey()) {
3490+
return Err(ChannelError::close("Invalid commitment tx signature from peer".to_owned()));
3491+
}
3492+
bitcoin_tx.txid
3493+
};
3494+
let mut htlcs_cloned: Vec<_> = commitment_stats.htlcs_included.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
3495+
3496+
// If our counterparty updated the channel fee in this commitment transaction, check that
3497+
// they can actually afford the new fee now.
3498+
let update_fee = if let Some((_, update_state)) = self.pending_update_fee {
3499+
update_state == FeeUpdateState::RemoteAnnounced
3500+
} else { false };
3501+
if update_fee {
3502+
debug_assert!(!funding.is_outbound());
3503+
let counterparty_reserve_we_require_msat = funding.holder_selected_channel_reserve_satoshis * 1000;
3504+
if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
3505+
return Err(ChannelError::close("Funding remote cannot afford proposed new fee".to_owned()));
3506+
}
3507+
}
3508+
#[cfg(any(test, fuzzing))]
3509+
{
3510+
if funding.is_outbound() {
3511+
let projected_commit_tx_info = funding.next_local_commitment_tx_fee_info_cached.lock().unwrap().take();
3512+
*funding.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
3513+
if let Some(info) = projected_commit_tx_info {
3514+
let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len()
3515+
+ self.holding_cell_htlc_updates.len();
3516+
if info.total_pending_htlcs == total_pending_htlcs
3517+
&& info.next_holder_htlc_id == self.next_holder_htlc_id
3518+
&& info.next_counterparty_htlc_id == self.next_counterparty_htlc_id
3519+
&& info.feerate == self.feerate_per_kw {
3520+
assert_eq!(commitment_stats.total_fee_sat, info.fee / 1000);
3521+
}
3522+
}
3523+
}
3524+
}
3525+
3526+
if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
3527+
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)));
3528+
}
3529+
3530+
// Up to LDK 0.0.115, HTLC information was required to be duplicated in the
3531+
// `htlcs_and_sigs` vec and in the `holder_commitment_tx` itself, both of which were passed
3532+
// in the `ChannelMonitorUpdate`. In 0.0.115, support for having a separate set of
3533+
// outbound-non-dust-HTLCSources in the `ChannelMonitorUpdate` was added, however for
3534+
// backwards compatibility, we never use it in production. To provide test coverage, here,
3535+
// we randomly decide (in test/fuzzing builds) to use the new vec sometimes.
3536+
#[allow(unused_assignments, unused_mut)]
3537+
let mut separate_nondust_htlc_sources = false;
3538+
#[cfg(all(feature = "std", any(test, fuzzing)))] {
3539+
use core::hash::{BuildHasher, Hasher};
3540+
// Get a random value using the only std API to do so - the DefaultHasher
3541+
let rand_val = std::collections::hash_map::RandomState::new().build_hasher().finish();
3542+
separate_nondust_htlc_sources = rand_val % 2 == 0;
3543+
}
3544+
3545+
let mut nondust_htlc_sources = Vec::with_capacity(htlcs_cloned.len());
3546+
let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
3547+
for (idx, (htlc, mut source_opt)) in htlcs_cloned.drain(..).enumerate() {
3548+
if let Some(_) = htlc.transaction_output_index {
3549+
let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
3550+
funding.get_counterparty_selected_contest_delay().unwrap(), &htlc, &self.channel_type,
3551+
&keys.broadcaster_delayed_payment_key, &keys.revocation_key);
3552+
3553+
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &self.channel_type, &keys);
3554+
let htlc_sighashtype = if self.channel_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
3555+
let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).p2wsh_signature_hash(0, &htlc_redeemscript, htlc.to_bitcoin_amount(), htlc_sighashtype).unwrap()[..]);
3556+
log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}.",
3557+
log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.to_public_key().serialize()),
3558+
encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), &self.channel_id());
3559+
if let Err(_) = self.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key.to_public_key()) {
3560+
return Err(ChannelError::close("Invalid HTLC tx signature from peer".to_owned()));
3561+
}
3562+
if !separate_nondust_htlc_sources {
3563+
htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
3564+
}
3565+
} else {
3566+
htlcs_and_sigs.push((htlc, None, source_opt.take()));
3567+
}
3568+
if separate_nondust_htlc_sources {
3569+
if let Some(source) = source_opt.take() {
3570+
nondust_htlc_sources.push(source);
3571+
}
3572+
}
3573+
debug_assert!(source_opt.is_none(), "HTLCSource should have been put somewhere");
3574+
}
3575+
3576+
let holder_commitment_tx = HolderCommitmentTransaction::new(
3577+
commitment_stats.tx,
3578+
msg.signature,
3579+
msg.htlc_signatures.clone(),
3580+
&funding.get_holder_pubkeys().funding_pubkey,
3581+
funding.counterparty_funding_pubkey()
3582+
);
3583+
3584+
self.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, commitment_stats.outbound_htlc_preimages)
3585+
.map_err(|_| ChannelError::close("Failed to validate our commitment".to_owned()))?;
3586+
3587+
Ok(LatestHolderCommitmentTXInfo {
3588+
commitment_tx: holder_commitment_tx,
3589+
htlc_outputs: htlcs_and_sigs,
3590+
nondust_htlc_sources,
3591+
})
3592+
}
3593+
34553594
/// Transaction nomenclature is somewhat confusing here as there are many different cases - a
34563595
/// transaction is referred to as "a's transaction" implying that a will be able to broadcast
34573596
/// the transaction. Thus, b will generally be sending a signature over such a transaction to
@@ -5494,145 +5633,10 @@ impl<SP: Deref> FundedChannel<SP> where
54945633
Ok(channel_monitor)
54955634
}
54965635

5497-
fn commitment_signed_check<L: Deref>(&self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<LatestHolderCommitmentTXInfo, ChannelError>
5498-
where L::Target: Logger
5499-
{
5500-
if self.context.channel_state.is_quiescent() {
5501-
return Err(ChannelError::WarnAndDisconnect("Got commitment_signed message while quiescent".to_owned()));
5502-
}
5503-
if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
5504-
return Err(ChannelError::close("Got commitment signed message when channel was not in an operational state".to_owned()));
5505-
}
5506-
if self.context.channel_state.is_peer_disconnected() {
5507-
return Err(ChannelError::close("Peer sent commitment_signed when we needed a channel_reestablish".to_owned()));
5508-
}
5509-
if self.context.channel_state.is_both_sides_shutdown() && self.context.last_sent_closing_fee.is_some() {
5510-
return Err(ChannelError::close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned()));
5511-
}
5512-
5513-
let funding_script = self.funding.get_funding_redeemscript();
5514-
5515-
let keys = self.context.build_holder_transaction_keys(&self.funding, self.holder_commitment_point.current_point());
5516-
5517-
let commitment_stats = self.context.build_commitment_transaction(&self.funding, self.holder_commitment_point.transaction_number(), &keys, true, false, logger);
5518-
let commitment_txid = {
5519-
let trusted_tx = commitment_stats.tx.trust();
5520-
let bitcoin_tx = trusted_tx.built_transaction();
5521-
let sighash = bitcoin_tx.get_sighash_all(&funding_script, self.funding.get_value_satoshis());
5522-
5523-
log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
5524-
log_bytes!(msg.signature.serialize_compact()[..]),
5525-
log_bytes!(self.funding.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
5526-
log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), &self.context.channel_id());
5527-
if let Err(_) = self.context.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &self.funding.counterparty_funding_pubkey()) {
5528-
return Err(ChannelError::close("Invalid commitment tx signature from peer".to_owned()));
5529-
}
5530-
bitcoin_tx.txid
5531-
};
5532-
let mut htlcs_cloned: Vec<_> = commitment_stats.htlcs_included.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
5533-
5534-
// If our counterparty updated the channel fee in this commitment transaction, check that
5535-
// they can actually afford the new fee now.
5536-
let update_fee = if let Some((_, update_state)) = self.context.pending_update_fee {
5537-
update_state == FeeUpdateState::RemoteAnnounced
5538-
} else { false };
5539-
if update_fee {
5540-
debug_assert!(!self.funding.is_outbound());
5541-
let counterparty_reserve_we_require_msat = self.funding.holder_selected_channel_reserve_satoshis * 1000;
5542-
if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
5543-
return Err(ChannelError::close("Funding remote cannot afford proposed new fee".to_owned()));
5544-
}
5545-
}
5546-
#[cfg(any(test, fuzzing))]
5547-
{
5548-
if self.funding.is_outbound() {
5549-
let projected_commit_tx_info = self.funding.next_local_commitment_tx_fee_info_cached.lock().unwrap().take();
5550-
*self.funding.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
5551-
if let Some(info) = projected_commit_tx_info {
5552-
let total_pending_htlcs = self.context.pending_inbound_htlcs.len() + self.context.pending_outbound_htlcs.len()
5553-
+ self.context.holding_cell_htlc_updates.len();
5554-
if info.total_pending_htlcs == total_pending_htlcs
5555-
&& info.next_holder_htlc_id == self.context.next_holder_htlc_id
5556-
&& info.next_counterparty_htlc_id == self.context.next_counterparty_htlc_id
5557-
&& info.feerate == self.context.feerate_per_kw {
5558-
assert_eq!(commitment_stats.total_fee_sat, info.fee / 1000);
5559-
}
5560-
}
5561-
}
5562-
}
5563-
5564-
if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
5565-
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)));
5566-
}
5567-
5568-
// Up to LDK 0.0.115, HTLC information was required to be duplicated in the
5569-
// `htlcs_and_sigs` vec and in the `holder_commitment_tx` itself, both of which were passed
5570-
// in the `ChannelMonitorUpdate`. In 0.0.115, support for having a separate set of
5571-
// outbound-non-dust-HTLCSources in the `ChannelMonitorUpdate` was added, however for
5572-
// backwards compatibility, we never use it in production. To provide test coverage, here,
5573-
// we randomly decide (in test/fuzzing builds) to use the new vec sometimes.
5574-
#[allow(unused_assignments, unused_mut)]
5575-
let mut separate_nondust_htlc_sources = false;
5576-
#[cfg(all(feature = "std", any(test, fuzzing)))] {
5577-
use core::hash::{BuildHasher, Hasher};
5578-
// Get a random value using the only std API to do so - the DefaultHasher
5579-
let rand_val = std::collections::hash_map::RandomState::new().build_hasher().finish();
5580-
separate_nondust_htlc_sources = rand_val % 2 == 0;
5581-
}
5582-
5583-
let mut nondust_htlc_sources = Vec::with_capacity(htlcs_cloned.len());
5584-
let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
5585-
for (idx, (htlc, mut source_opt)) in htlcs_cloned.drain(..).enumerate() {
5586-
if let Some(_) = htlc.transaction_output_index {
5587-
let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
5588-
self.funding.get_counterparty_selected_contest_delay().unwrap(), &htlc, &self.context.channel_type,
5589-
&keys.broadcaster_delayed_payment_key, &keys.revocation_key);
5590-
5591-
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &self.context.channel_type, &keys);
5592-
let htlc_sighashtype = if self.context.channel_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
5593-
let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).p2wsh_signature_hash(0, &htlc_redeemscript, htlc.to_bitcoin_amount(), htlc_sighashtype).unwrap()[..]);
5594-
log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}.",
5595-
log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.to_public_key().serialize()),
5596-
encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), &self.context.channel_id());
5597-
if let Err(_) = self.context.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key.to_public_key()) {
5598-
return Err(ChannelError::close("Invalid HTLC tx signature from peer".to_owned()));
5599-
}
5600-
if !separate_nondust_htlc_sources {
5601-
htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
5602-
}
5603-
} else {
5604-
htlcs_and_sigs.push((htlc, None, source_opt.take()));
5605-
}
5606-
if separate_nondust_htlc_sources {
5607-
if let Some(source) = source_opt.take() {
5608-
nondust_htlc_sources.push(source);
5609-
}
5610-
}
5611-
debug_assert!(source_opt.is_none(), "HTLCSource should have been put somewhere");
5612-
}
5613-
5614-
let holder_commitment_tx = HolderCommitmentTransaction::new(
5615-
commitment_stats.tx,
5616-
msg.signature,
5617-
msg.htlc_signatures.clone(),
5618-
&self.funding.get_holder_pubkeys().funding_pubkey,
5619-
self.funding.counterparty_funding_pubkey()
5620-
);
5621-
5622-
self.context.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, commitment_stats.outbound_htlc_preimages)
5623-
.map_err(|_| ChannelError::close("Failed to validate our commitment".to_owned()))?;
5624-
5625-
Ok(LatestHolderCommitmentTXInfo {
5626-
commitment_tx: holder_commitment_tx,
5627-
htlc_outputs: htlcs_and_sigs,
5628-
nondust_htlc_sources,
5629-
})
5630-
}
5631-
56325636
pub fn commitment_signed<L: Deref>(&mut self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<Option<ChannelMonitorUpdate>, ChannelError>
56335637
where L::Target: Logger
56345638
{
5635-
let commitment_tx_info = self.commitment_signed_check(msg, logger)?;
5639+
let commitment_tx_info = self.context.commitment_signed_check(&self.funding, &self.holder_commitment_point, msg, logger)?;
56365640

56375641
// Update state now that we've passed all the can-fail calls...
56385642
let mut need_commitment = false;

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