Merge pull request #1828 from lightning-signer/2022-11-non-zero-fee-anchors

Re-add support for non-zero-fee-anchors to chan_utils

Author: TheBlueMatt

fuzz/src/full_stack.rs

@@ -311,7 +311,7 @@ impl KeysInterface for KeyProvider {
 				SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, ctr]).unwrap(),
 				[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, ctr],
 				channel_value_satoshis,
-				[0; 32]
+				[0; 32],
 			)
 		} else {
 			InMemorySigner::new(
@@ -324,7 +324,7 @@ impl KeysInterface for KeyProvider {
 				SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, ctr]).unwrap(),
 				[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, ctr],
 				channel_value_satoshis,
-				[0; 32]
+				[0; 32],
 			)
 		})
 	}

lightning/src/chain/channelmonitor.rs

@@ -4044,7 +4044,7 @@ mod tests {
 			SecretKey::from_slice(&[41; 32]).unwrap(),
 			[41; 32],
 			0,
-			[0; 32]
+			[0; 32],
 		);
 
 		let counterparty_pubkeys = ChannelPublicKeys {
@@ -4065,6 +4065,7 @@ mod tests {
 			}),
 			funding_outpoint: Some(funding_outpoint),
 			opt_anchors: None,
+			opt_non_zero_fee_anchors: None,
 		};
 		// Prune with one old state and a holder commitment tx holding a few overlaps with the
 		// old state.

lightning/src/chain/keysinterface.rs

@@ -533,7 +533,8 @@ impl InMemorySigner {
 		htlc_base_key: SecretKey,
 		commitment_seed: [u8; 32],
 		channel_value_satoshis: u64,
-		channel_keys_id: [u8; 32]) -> InMemorySigner {
+		channel_keys_id: [u8; 32],
+	) -> InMemorySigner {
 		let holder_channel_pubkeys =
 			InMemorySigner::make_holder_keys(secp_ctx, &funding_key, &revocation_base_key,
 			                                     &payment_key, &delayed_payment_base_key,
@@ -704,7 +705,8 @@ impl BaseSign for InMemorySigner {
 
 		let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
 		for htlc in commitment_tx.htlcs() {
-			let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+			let channel_parameters = self.get_channel_parameters();
+			let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, self.opt_anchors(), channel_parameters.opt_non_zero_fee_anchors.is_some(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &keys);
 			let htlc_sighashtype = if self.opt_anchors() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
 			let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, htlc_sighashtype).unwrap()[..]);
@@ -1035,7 +1037,7 @@ impl KeysManager {
 			htlc_base_key,
 			commitment_seed,
 			channel_value_satoshis,
-			params.clone()
+			params.clone(),
 		)
 	}
 

lightning/src/ln/chan_utils.rs

@@ -660,7 +660,7 @@ pub fn make_funding_redeemscript(broadcaster: &PublicKey, countersignatory: &Pub
 ///
 /// Panics if htlc.transaction_output_index.is_none() (as such HTLCs do not appear in the
 /// commitment transaction).
-pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, contest_delay: u16, htlc: &HTLCOutputInCommitment, opt_anchors: bool, broadcaster_delayed_payment_key: &PublicKey, revocation_key: &PublicKey) -> Transaction {
+pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, contest_delay: u16, htlc: &HTLCOutputInCommitment, opt_anchors: bool, use_non_zero_fee_anchors: bool, broadcaster_delayed_payment_key: &PublicKey, revocation_key: &PublicKey) -> Transaction {
 	let mut txins: Vec<TxIn> = Vec::new();
 	txins.push(TxIn {
 		previous_output: OutPoint {
@@ -677,7 +677,7 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
 	} else {
 		htlc_success_tx_weight(opt_anchors)
 	};
-	let output_value = if opt_anchors {
+	let output_value = if opt_anchors && !use_non_zero_fee_anchors {
 		htlc.amount_msat / 1000
 	} else {
 		let total_fee = feerate_per_kw as u64 * weight / 1000;
@@ -765,7 +765,11 @@ pub struct ChannelTransactionParameters {
 	pub funding_outpoint: Option<chain::transaction::OutPoint>,
 	/// Are anchors (zero fee HTLC transaction variant) used for this channel. Boolean is
 	/// serialization backwards-compatible.
-	pub opt_anchors: Option<()>
+	pub opt_anchors: Option<()>,
+	/// Are non-zero-fee anchors are enabled (used in conjuction with opt_anchors)
+	/// It is intended merely for backwards compatibility with signers that need it.
+	/// There is no support for this feature in LDK channel negotiation.
+	pub opt_non_zero_fee_anchors: Option<()>,
 }
 
 /// Late-bound per-channel counterparty data used to build transactions.
@@ -820,6 +824,7 @@ impl_writeable_tlv_based!(ChannelTransactionParameters, {
 	(6, counterparty_parameters, option),
 	(8, funding_outpoint, option),
 	(10, opt_anchors, option),
+	(12, opt_non_zero_fee_anchors, option),
 });
 
 /// Static channel fields used to build transactions given per-commitment fields, organized by
@@ -942,7 +947,8 @@ impl HolderCommitmentTransaction {
 			is_outbound_from_holder: false,
 			counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: channel_pubkeys.clone(), selected_contest_delay: 0 }),
 			funding_outpoint: Some(chain::transaction::OutPoint { txid: Txid::all_zeros(), index: 0 }),
-			opt_anchors: None
+			opt_anchors: None,
+			opt_non_zero_fee_anchors: None,
 		};
 		let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();
 		let inner = CommitmentTransaction::new_with_auxiliary_htlc_data(0, 0, 0, false, dummy_key.clone(), dummy_key.clone(), keys, 0, &mut htlcs_with_aux, &channel_parameters.as_counterparty_broadcastable());
@@ -1160,6 +1166,8 @@ pub struct CommitmentTransaction {
 	htlcs: Vec<HTLCOutputInCommitment>,
 	// A boolean that is serialization backwards-compatible
 	opt_anchors: Option<()>,
+	// Whether non-zero-fee anchors should be used
+	opt_non_zero_fee_anchors: Option<()>,
 	// A cache of the parties' pubkeys required to construct the transaction, see doc for trust()
 	keys: TxCreationKeys,
 	// For access to the pre-built transaction, see doc for trust()
@@ -1193,6 +1201,7 @@ impl_writeable_tlv_based!(CommitmentTransaction, {
 	(10, built, required),
 	(12, htlcs, vec_type),
 	(14, opt_anchors, option),
+	(16, opt_non_zero_fee_anchors, option),
 });
 
 impl CommitmentTransaction {
@@ -1225,9 +1234,18 @@ impl CommitmentTransaction {
 				transaction,
 				txid
 			},
+			opt_non_zero_fee_anchors: None,
 		}
 	}
 
+	/// Use non-zero fee anchors
+	///
+	/// (C-not exported) due to move, and also not likely to be useful for binding users
+	pub fn with_non_zero_fee_anchors(mut self) -> Self {
+		self.opt_non_zero_fee_anchors = Some(());
+		self
+	}
+
 	fn internal_rebuild_transaction(&self, keys: &TxCreationKeys, channel_parameters: &DirectedChannelTransactionParameters, broadcaster_funding_key: &PublicKey, countersignatory_funding_key: &PublicKey) -> Result<BuiltCommitmentTransaction, ()> {
 		let (obscured_commitment_transaction_number, txins) = Self::internal_build_inputs(self.commitment_number, channel_parameters);
 
@@ -1492,7 +1510,7 @@ impl<'a> TrustedCommitmentTransaction<'a> {
 
 		for this_htlc in inner.htlcs.iter() {
 			assert!(this_htlc.transaction_output_index.is_some());
-			let htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+			let htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), self.opt_non_zero_fee_anchors.is_some(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
 			let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, self.opt_anchors(), &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key);
 
@@ -1514,7 +1532,7 @@ impl<'a> TrustedCommitmentTransaction<'a> {
 		// Further, we should never be provided the preimage for an HTLC-Timeout transaction.
 		if  this_htlc.offered && preimage.is_some() { unreachable!(); }
 
-		let mut htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+		let mut htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), self.opt_non_zero_fee_anchors.is_some(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
 		let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, self.opt_anchors(), &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key);
 
@@ -1614,7 +1632,8 @@ mod tests {
 			is_outbound_from_holder: false,
 			counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: counterparty_pubkeys.clone(), selected_contest_delay: 0 }),
 			funding_outpoint: Some(chain::transaction::OutPoint { txid: Txid::all_zeros(), index: 0 }),
-			opt_anchors: None
+			opt_anchors: None,
+			opt_non_zero_fee_anchors: None,
 		};
 
 		let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();

lightning/src/ln/channel.rs

@@ -1038,6 +1038,7 @@ impl<Signer: Sign> Channel<Signer> {
 				counterparty_parameters: None,
 				funding_outpoint: None,
 				opt_anchors: if opt_anchors { Some(()) } else { None },
+				opt_non_zero_fee_anchors: None
 			},
 			funding_transaction: None,
 
@@ -1383,6 +1384,7 @@ impl<Signer: Sign> Channel<Signer> {
 				}),
 				funding_outpoint: None,
 				opt_anchors: if opt_anchors { Some(()) } else { None },
+				opt_non_zero_fee_anchors: None
 			},
 			funding_transaction: None,
 
@@ -3016,7 +3018,7 @@ impl<Signer: Sign> Channel<Signer> {
 			if let Some(_) = htlc.transaction_output_index {
 				let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
 					self.get_counterparty_selected_contest_delay().unwrap(), &htlc, self.opt_anchors(),
-					&keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+					false, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
 				let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &keys);
 				let htlc_sighashtype = if self.opt_anchors() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
@@ -5743,7 +5745,7 @@ impl<Signer: Sign> Channel<Signer> {
 
 			for (ref htlc_sig, ref htlc) in htlc_signatures.iter().zip(htlcs) {
 				log_trace!(logger, "Signed remote HTLC tx {} with redeemscript {} with pubkey {} -> {} in channel {}",
-					encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_txid, commitment_stats.feerate_per_kw, self.get_holder_selected_contest_delay(), htlc, self.opt_anchors(), &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
+					encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_txid, commitment_stats.feerate_per_kw, self.get_holder_selected_contest_delay(), htlc, self.opt_anchors(), false, &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
 					encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &counterparty_keys)),
 					log_bytes!(counterparty_keys.broadcaster_htlc_key.serialize()),
 					log_bytes!(htlc_sig.serialize_compact()[..]), log_bytes!(self.channel_id()));
@@ -7250,7 +7252,7 @@ mod tests {
 			// These aren't set in the test vectors:
 			[0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff],
 			10_000_000,
-			[0; 32]
+			[0; 32],
 		);
 
 		assert_eq!(signer.pubkeys().funding_pubkey.serialize()[..],
@@ -7368,7 +7370,7 @@ mod tests {
 					let ref htlc = htlcs[$htlc_idx];
 					let htlc_tx = chan_utils::build_htlc_transaction(&unsigned_tx.txid, chan.feerate_per_kw,
 						chan.get_counterparty_selected_contest_delay().unwrap(),
-						&htlc, $opt_anchors, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+						&htlc, $opt_anchors, false, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 					let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, $opt_anchors, &keys);
 					let htlc_sighashtype = if $opt_anchors { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
 					let htlc_sighash = Message::from_slice(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, htlc_sighashtype).unwrap()[..]).unwrap();

lightning/src/util/enforcing_trait_impls.rs

@@ -157,7 +157,7 @@ impl BaseSign for EnforcingSigner {
 		for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) {
 			assert!(this_htlc.transaction_output_index.is_some());
 			let keys = trusted_tx.keys();
-			let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, trusted_tx.feerate_per_kw(), holder_csv, &this_htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+			let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, trusted_tx.feerate_per_kw(), holder_csv, &this_htlc, self.opt_anchors(), false, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
 			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, self.opt_anchors(), &keys);