[Custom Transactions] Demo the TxBuilder trait

lightning/src/chain/channelmonitor.rs

@@ -547,6 +547,9 @@ pub(crate) enum ChannelMonitorUpdateStep {
 		feerate_per_kw: Option<u32>,
 		to_broadcaster_value_sat: Option<u64>,
 		to_countersignatory_value_sat: Option<u64>,
+		// See docs for `CommitmentStats`, and `ChannelContext::build_commitment_transaction`
+		value_to_self_with_offset_msat: Option<u64>,
+		counterparty_dust_limit_satoshis: Option<u64>,
 	},
 	PaymentPreimage {
 		payment_preimage: PaymentPreimage,
@@ -598,6 +601,8 @@ impl_writeable_tlv_based_enum_upgradable!(ChannelMonitorUpdateStep,
 		(4, their_per_commitment_point, required),
 		(5, to_countersignatory_value_sat, option),
 		(6, htlc_outputs, required_vec),
+		(7, value_to_self_with_offset_msat, option),
+		(9, counterparty_dust_limit_satoshis, option),
 	},
 	(2, PaymentPreimage) => {
 		(0, payment_preimage, required),
@@ -1024,8 +1029,8 @@ pub(crate) struct ChannelMonitorImpl<Signer: EcdsaChannelSigner> {
 	/// monitors created after 0.0.117.
 	///
 	/// Ordering of tuple data: (their_per_commitment_point, feerate_per_kw, to_broadcaster_sats,
-	/// to_countersignatory_sats)
-	initial_counterparty_commitment_info: Option<(PublicKey, u32, u64, u64)>,
+	/// to_countersignatory_sats, value_to_self_with_offset_msat, counterparty_dust_limit_satoshis)
+	initial_counterparty_commitment_info: Option<(PublicKey, u32, u64, u64, u64, u64)>,
 
 	/// The first block height at which we had no remaining claimable balances.
 	balances_empty_height: Option<u32>,
@@ -1501,15 +1506,16 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitor<Signer> {
 	pub(crate) fn provide_initial_counterparty_commitment_tx<L: Deref>(
 		&self, txid: Txid, htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Box<HTLCSource>>)>,
 		commitment_number: u64, their_cur_per_commitment_point: PublicKey, feerate_per_kw: u32,
-		to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, logger: &L,
+		to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, value_to_self_with_offset_msat: u64, counterparty_dust_limit_satoshis: u64,
+		logger: &L,
 	)
 	where L::Target: Logger
 	{
 		let mut inner = self.inner.lock().unwrap();
 		let logger = WithChannelMonitor::from_impl(logger, &*inner, None);
 		inner.provide_initial_counterparty_commitment_tx(txid,
 			htlc_outputs, commitment_number, their_cur_per_commitment_point, feerate_per_kw,
-			to_broadcaster_value_sat, to_countersignatory_value_sat, &logger);
+			to_broadcaster_value_sat, to_countersignatory_value_sat, value_to_self_with_offset_msat, counterparty_dust_limit_satoshis, &logger);
 	}
 
 	/// Informs this monitor of the latest counterparty (ie non-broadcastable) commitment transaction.
@@ -2874,10 +2880,11 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 	fn provide_initial_counterparty_commitment_tx<L: Deref>(
 		&mut self, txid: Txid, htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Box<HTLCSource>>)>,
 		commitment_number: u64, their_per_commitment_point: PublicKey, feerate_per_kw: u32,
-		to_broadcaster_value: u64, to_countersignatory_value: u64, logger: &WithChannelMonitor<L>,
+		to_broadcaster_value: u64, to_countersignatory_value: u64, value_to_self_with_offset_msat: u64, counterparty_dust_limit_satoshis: u64,
+		logger: &WithChannelMonitor<L>,
 	) where L::Target: Logger {
 		self.initial_counterparty_commitment_info = Some((their_per_commitment_point.clone(),
-			feerate_per_kw, to_broadcaster_value, to_countersignatory_value));
+			feerate_per_kw, to_broadcaster_value, to_countersignatory_value, value_to_self_with_offset_msat, counterparty_dust_limit_satoshis));
 
 		#[cfg(debug_assertions)] {
 			let rebuilt_commitment_tx = self.initial_counterparty_commitment_tx().unwrap();
@@ -3437,14 +3444,17 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 	}
 
 	fn initial_counterparty_commitment_tx(&mut self) -> Option<CommitmentTransaction> {
-		let (their_per_commitment_point, feerate_per_kw, to_broadcaster_value,
-			to_countersignatory_value) = self.initial_counterparty_commitment_info?;
+		let (their_per_commitment_point, feerate_per_kw, _to_broadcaster_value,
+			_to_countersignatory_value, value_to_self_with_offset_msat, counterparty_dust_limit_satoshis) = self.initial_counterparty_commitment_info?;
+		let channel_transaction_parameters = &self.onchain_tx_handler.channel_transaction_parameters;
 		let htlc_outputs = vec![];
 
-		let commitment_tx = self.build_counterparty_commitment_tx(INITIAL_COMMITMENT_NUMBER,
-			&their_per_commitment_point, to_broadcaster_value, to_countersignatory_value,
-			feerate_per_kw, htlc_outputs);
-		Some(commitment_tx)
+		use crate::sign::tx_builder::{SpecTxBuilder, TxBuilder};
+		let stats = TxBuilder::build_commitment_transaction(&SpecTxBuilder {}, false, INITIAL_COMMITMENT_NUMBER,
+			&their_per_commitment_point, channel_transaction_parameters, &self.onchain_tx_handler.secp_ctx,
+			self.channel_value_satoshis, value_to_self_with_offset_msat, htlc_outputs, feerate_per_kw, counterparty_dust_limit_satoshis);
+
+		Some(stats.tx)
 	}
 
 	fn build_counterparty_commitment_tx(
@@ -3477,7 +3487,8 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 					ref htlc_outputs, commitment_number, their_per_commitment_point,
 					feerate_per_kw: Some(feerate_per_kw),
 					to_broadcaster_value_sat: Some(to_broadcaster_value),
-					to_countersignatory_value_sat: Some(to_countersignatory_value) } => {
+					to_countersignatory_value_sat: Some(to_countersignatory_value),
+					value_to_self_with_offset_msat: None, counterparty_dust_limit_satoshis: None } => {
 
 					let nondust_htlcs = htlc_outputs.iter().filter_map(|(htlc, _)| {
 						htlc.transaction_output_index.map(|_| (htlc.clone(), None))
@@ -3491,6 +3502,25 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 
 					Some(commitment_tx)
 				},
+				&ChannelMonitorUpdateStep::LatestCounterpartyCommitmentTXInfo { commitment_txid,
+					ref htlc_outputs, commitment_number, their_per_commitment_point,
+					feerate_per_kw: Some(feerate_per_kw),
+					to_broadcaster_value_sat: Some(_to_broadcaster_value),
+					to_countersignatory_value_sat: Some(_to_countersignatory_value),
+					value_to_self_with_offset_msat: Some(value_to_self_with_offset), counterparty_dust_limit_satoshis: Some(dust_limit_satoshis) } => {
+
+					let channel_transaction_parameters = &self.onchain_tx_handler.channel_transaction_parameters;
+					let htlc_outputs = htlc_outputs.iter().map(|(htlc, source)| (htlc.clone(), source.as_ref().map(|s| s.as_ref()))).collect();
+
+					use crate::sign::tx_builder::{SpecTxBuilder, TxBuilder};
+					let stats = TxBuilder::build_commitment_transaction(&SpecTxBuilder {}, false, commitment_number, &their_per_commitment_point,
+						channel_transaction_parameters, &self.onchain_tx_handler.secp_ctx, self.channel_value_satoshis, value_to_self_with_offset,
+						htlc_outputs, feerate_per_kw, dust_limit_satoshis);
+
+					debug_assert_eq!(stats.tx.trust().txid(), commitment_txid);
+
+					Some(stats.tx)
+				},
 				_ => None,
 			}
 		}).collect()