Replace opt_anchors with ChannelTypeFeatures

This change modifies six structs that were keeping
track of anchors features with an `opt_anchors` field,
as well as another field keeping track of nonzero-fee-
anchor-support.

Its scope is rather pervasive throughout the unit tests, but the basis for the changes is mostly contained within package.rs, channelmonitor.rs, and channel.rs. The original struct that was meant to be changed here was `ChannelTransactionParameters`.

Author: arik-so

lightning/src/chain/channelmonitor.rs

@@ -1600,7 +1600,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 					debug_assert!(htlc_input_idx_opt.is_some());
 					BitcoinOutPoint::new(*txid, htlc_input_idx_opt.unwrap_or(0))
 				} else {
-					debug_assert!(!self.onchain_tx_handler.opt_anchors());
+					debug_assert!(!self.onchain_tx_handler.channel_type_features().supports_anchors_zero_fee_htlc_tx());
 					BitcoinOutPoint::new(*txid, 0)
 				}
 			} else {
@@ -2459,10 +2459,10 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 						// If the channel supports anchor outputs, we'll need to emit an external
 						// event to be consumed such that a child transaction is broadcast with a
 						// high enough feerate for the parent commitment transaction to confirm.
-						if self.onchain_tx_handler.opt_anchors() {
+						if self.onchain_tx_handler.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 							let funding_output = HolderFundingOutput::build(
 								self.funding_redeemscript.clone(), self.channel_value_satoshis,
-								self.onchain_tx_handler.opt_anchors(),
+								self.onchain_tx_handler.channel_type_features(),
 							);
 							let best_block_height = self.best_block.height();
 							let commitment_package = PackageTemplate::build_package(
@@ -2653,7 +2653,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 			// First, process non-htlc outputs (to_holder & to_counterparty)
 			for (idx, outp) in tx.output.iter().enumerate() {
 				if outp.script_pubkey == revokeable_p2wsh {
-					let revk_outp = RevokedOutput::build(per_commitment_point, self.counterparty_commitment_params.counterparty_delayed_payment_base_key, self.counterparty_commitment_params.counterparty_htlc_base_key, per_commitment_key, outp.value, self.counterparty_commitment_params.on_counterparty_tx_csv, self.onchain_tx_handler.opt_anchors());
+					let revk_outp = RevokedOutput::build(per_commitment_point, self.counterparty_commitment_params.counterparty_delayed_payment_base_key, self.counterparty_commitment_params.counterparty_htlc_base_key, per_commitment_key, outp.value, self.counterparty_commitment_params.on_counterparty_tx_csv, self.onchain_tx_handler.channel_type_features().supports_anchors_zero_fee_htlc_tx());
 					let justice_package = PackageTemplate::build_package(commitment_txid, idx as u32, PackageSolvingData::RevokedOutput(revk_outp), height + self.counterparty_commitment_params.on_counterparty_tx_csv as u32, height);
 					claimable_outpoints.push(justice_package);
 					to_counterparty_output_info =
@@ -2671,7 +2671,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 							return (claimable_outpoints, (commitment_txid, watch_outputs),
 								to_counterparty_output_info);
 						}
-						let revk_htlc_outp = RevokedHTLCOutput::build(per_commitment_point, self.counterparty_commitment_params.counterparty_delayed_payment_base_key, self.counterparty_commitment_params.counterparty_htlc_base_key, per_commitment_key, htlc.amount_msat / 1000, htlc.clone(), self.onchain_tx_handler.channel_transaction_parameters.opt_anchors.is_some());
+						let revk_htlc_outp = RevokedHTLCOutput::build(per_commitment_point, self.counterparty_commitment_params.counterparty_delayed_payment_base_key, self.counterparty_commitment_params.counterparty_htlc_base_key, per_commitment_key, htlc.amount_msat / 1000, htlc.clone(), &self.onchain_tx_handler.channel_transaction_parameters.channel_type_features);
 						let justice_package = PackageTemplate::build_package(commitment_txid, transaction_output_index, PackageSolvingData::RevokedHTLCOutput(revk_htlc_outp), htlc.cltv_expiry, height);
 						claimable_outpoints.push(justice_package);
 					}
@@ -2789,13 +2789,13 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 							CounterpartyOfferedHTLCOutput::build(*per_commitment_point,
 								self.counterparty_commitment_params.counterparty_delayed_payment_base_key,
 								self.counterparty_commitment_params.counterparty_htlc_base_key,
-								preimage.unwrap(), htlc.clone(), self.onchain_tx_handler.opt_anchors()))
+								preimage.unwrap(), htlc.clone(), self.onchain_tx_handler.channel_type_features()))
 					} else {
 						PackageSolvingData::CounterpartyReceivedHTLCOutput(
 							CounterpartyReceivedHTLCOutput::build(*per_commitment_point,
 								self.counterparty_commitment_params.counterparty_delayed_payment_base_key,
 								self.counterparty_commitment_params.counterparty_htlc_base_key,
-								htlc.clone(), self.onchain_tx_handler.opt_anchors()))
+								htlc.clone(), self.onchain_tx_handler.channel_type_features()))
 					};
 					let counterparty_package = PackageTemplate::build_package(commitment_txid, transaction_output_index, counterparty_htlc_outp, htlc.cltv_expiry, 0);
 					claimable_outpoints.push(counterparty_package);
@@ -2866,7 +2866,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 			if let Some(transaction_output_index) = htlc.transaction_output_index {
 				let htlc_output = if htlc.offered {
 					let htlc_output = HolderHTLCOutput::build_offered(
-						htlc.amount_msat, htlc.cltv_expiry, self.onchain_tx_handler.opt_anchors()
+						htlc.amount_msat, htlc.cltv_expiry, self.onchain_tx_handler.channel_type_features()
 					);
 					htlc_output
 				} else {
@@ -2877,7 +2877,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 						continue;
 					};
 					let htlc_output = HolderHTLCOutput::build_accepted(
-						payment_preimage, htlc.amount_msat, self.onchain_tx_handler.opt_anchors()
+						payment_preimage, htlc.amount_msat, self.onchain_tx_handler.channel_type_features()
 					);
 					htlc_output
 				};
@@ -2961,7 +2961,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 		let mut holder_transactions = vec![commitment_tx];
 		// When anchor outputs are present, the HTLC transactions are only valid once the commitment
 		// transaction confirms.
-		if self.onchain_tx_handler.opt_anchors() {
+		if self.onchain_tx_handler.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 			return holder_transactions;
 		}
 		for htlc in self.current_holder_commitment_tx.htlc_outputs.iter() {
@@ -2999,7 +2999,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 		let mut holder_transactions = vec![commitment_tx];
 		// When anchor outputs are present, the HTLC transactions are only final once the commitment
 		// transaction confirms due to the CSV 1 encumberance.
-		if self.onchain_tx_handler.opt_anchors() {
+		if self.onchain_tx_handler.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 			return holder_transactions;
 		}
 		for htlc in self.current_holder_commitment_tx.htlc_outputs.iter() {
@@ -3223,7 +3223,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 
 		let should_broadcast = self.should_broadcast_holder_commitment_txn(logger);
 		if should_broadcast {
-			let funding_outp = HolderFundingOutput::build(self.funding_redeemscript.clone(), self.channel_value_satoshis, self.onchain_tx_handler.opt_anchors());
+			let funding_outp = HolderFundingOutput::build(self.funding_redeemscript.clone(), self.channel_value_satoshis, self.onchain_tx_handler.channel_type_features());
 			let commitment_package = PackageTemplate::build_package(self.funding_info.0.txid.clone(), self.funding_info.0.index as u32, PackageSolvingData::HolderFundingOutput(funding_outp), self.best_block.height(), self.best_block.height());
 			claimable_outpoints.push(commitment_package);
 			self.pending_monitor_events.push(MonitorEvent::CommitmentTxConfirmed(self.funding_info.0));
@@ -3232,7 +3232,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 			// We can't broadcast our HTLC transactions while the commitment transaction is
 			// unconfirmed. We'll delay doing so until we detect the confirmed commitment in
 			// `transactions_confirmed`.
-			if !self.onchain_tx_handler.opt_anchors() {
+			if !self.onchain_tx_handler.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 				// Because we're broadcasting a commitment transaction, we should construct the package
 				// assuming it gets confirmed in the next block. Sadly, we have code which considers
 				// "not yet confirmed" things as discardable, so we cannot do that here.
@@ -4160,6 +4160,7 @@ mod tests {
 	use crate::sync::{Arc, Mutex};
 	use crate::io;
 	use bitcoin::{PackedLockTime, Sequence, Witness};
+	use crate::ln::features::ChannelTypeFeatures;
 	use crate::prelude::*;
 
 	fn do_test_funding_spend_refuses_updates(use_local_txn: bool) {
@@ -4333,8 +4334,7 @@ mod tests {
 				selected_contest_delay: 67,
 			}),
 			funding_outpoint: Some(funding_outpoint),
-			opt_anchors: None,
-			opt_non_zero_fee_anchors: None,
+			channel_type_features: ChannelTypeFeatures::only_static_remote_key()
 		};
 		// Prune with one old state and a holder commitment tx holding a few overlaps with the
 		// old state.
@@ -4450,7 +4450,7 @@ mod tests {
 		let txid = Txid::from_hex("56944c5d3f98413ef45cf54545538103cc9f298e0575820ad3591376e2e0f65d").unwrap();
 
 		// Justice tx with 1 to_holder, 2 revoked offered HTLCs, 1 revoked received HTLCs
-		for &opt_anchors in [false, true].iter() {
+		for channel_type_features in [ChannelTypeFeatures::only_static_remote_key(), ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies()].iter() {
 			let mut claim_tx = Transaction { version: 0, lock_time: PackedLockTime::ZERO, input: Vec::new(), output: Vec::new() };
 			let mut sum_actual_sigs = 0;
 			for i in 0..4 {
@@ -4469,20 +4469,20 @@ mod tests {
 				value: 0,
 			});
 			let base_weight = claim_tx.weight();
-			let inputs_weight = vec![WEIGHT_REVOKED_OUTPUT, weight_revoked_offered_htlc(opt_anchors), weight_revoked_offered_htlc(opt_anchors), weight_revoked_received_htlc(opt_anchors)];
+			let inputs_weight = vec![WEIGHT_REVOKED_OUTPUT, weight_revoked_offered_htlc(channel_type_features), weight_revoked_offered_htlc(channel_type_features), weight_revoked_received_htlc(channel_type_features)];
 			let mut inputs_total_weight = 2; // count segwit flags
 			{
 				let mut sighash_parts = sighash::SighashCache::new(&mut claim_tx);
 				for (idx, inp) in inputs_weight.iter().enumerate() {
-					sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, opt_anchors);
+					sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, channel_type_features);
 					inputs_total_weight += inp;
 				}
 			}
 			assert_eq!(base_weight + inputs_total_weight as usize,  claim_tx.weight() + /* max_length_sig */ (73 * inputs_weight.len() - sum_actual_sigs));
 		}
 
 		// Claim tx with 1 offered HTLCs, 3 received HTLCs
-		for &opt_anchors in [false, true].iter() {
+		for channel_type_features in [ChannelTypeFeatures::only_static_remote_key(), ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies()].iter() {
 			let mut claim_tx = Transaction { version: 0, lock_time: PackedLockTime::ZERO, input: Vec::new(), output: Vec::new() };
 			let mut sum_actual_sigs = 0;
 			for i in 0..4 {
@@ -4501,20 +4501,20 @@ mod tests {
 				value: 0,
 			});
 			let base_weight = claim_tx.weight();
-			let inputs_weight = vec![weight_offered_htlc(opt_anchors), weight_received_htlc(opt_anchors), weight_received_htlc(opt_anchors), weight_received_htlc(opt_anchors)];
+			let inputs_weight = vec![weight_offered_htlc(channel_type_features), weight_received_htlc(channel_type_features), weight_received_htlc(channel_type_features), weight_received_htlc(channel_type_features)];
 			let mut inputs_total_weight = 2; // count segwit flags
 			{
 				let mut sighash_parts = sighash::SighashCache::new(&mut claim_tx);
 				for (idx, inp) in inputs_weight.iter().enumerate() {
-					sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, opt_anchors);
+					sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, channel_type_features);
 					inputs_total_weight += inp;
 				}
 			}
 			assert_eq!(base_weight + inputs_total_weight as usize,  claim_tx.weight() + /* max_length_sig */ (73 * inputs_weight.len() - sum_actual_sigs));
 		}
 
 		// Justice tx with 1 revoked HTLC-Success tx output
-		for &opt_anchors in [false, true].iter() {
+		for channel_type_features in [ChannelTypeFeatures::only_static_remote_key(), ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies()].iter() {
 			let mut claim_tx = Transaction { version: 0, lock_time: PackedLockTime::ZERO, input: Vec::new(), output: Vec::new() };
 			let mut sum_actual_sigs = 0;
 			claim_tx.input.push(TxIn {
@@ -4536,7 +4536,7 @@ mod tests {
 			{
 				let mut sighash_parts = sighash::SighashCache::new(&mut claim_tx);
 				for (idx, inp) in inputs_weight.iter().enumerate() {
-					sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, opt_anchors);
+					sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, channel_type_features);
 					inputs_total_weight += inp;
 				}
 			}

lightning/src/chain/onchaintx.rs

@@ -52,6 +52,7 @@ use core::ops::Deref;
 use core::mem::replace;
 #[cfg(anchors)]
 use core::mem::swap;
+use crate::ln::features::ChannelTypeFeatures;
 
 const MAX_ALLOC_SIZE: usize = 64*1024;
 
@@ -1215,8 +1216,8 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 			.or_else(|| self.prev_holder_commitment.as_ref().map(|c| find_htlc(c)).flatten())
 	}
 
-	pub(crate) fn opt_anchors(&self) -> bool {
-		self.channel_transaction_parameters.opt_anchors.is_some()
+	pub(crate) fn channel_type_features(&self) -> ChannelTypeFeatures {
+		self.channel_transaction_parameters.channel_type_features.clone()
 	}
 
 	#[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]