Replace `opt_anchors` with `ChannelTypeFeatures`
[rust-lightning] / lightning / src / ln / chan_utils.rs
index adae41381d64756aad664f71f2297d757cc17e96..d570347fef879af540cdfea9f5a68e9b22f3f57f 100644 (file)
@@ -24,7 +24,7 @@ use bitcoin::hash_types::{Txid, PubkeyHash};
 use crate::sign::EntropySource;
 use crate::ln::{PaymentHash, PaymentPreimage};
 use crate::ln::msgs::DecodeError;
-use crate::util::ser::{Readable, Writeable, Writer};
+use crate::util::ser::{Readable, RequiredWrapper, Writeable, Writer};
 use crate::util::transaction_utils;
 
 use bitcoin::secp256k1::{SecretKey, PublicKey, Scalar};
@@ -69,18 +69,18 @@ pub const HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT: u64 = 327;
 
 /// Gets the weight for an HTLC-Success transaction.
 #[inline]
-pub fn htlc_success_tx_weight(opt_anchors: bool) -> u64 {
+pub fn htlc_success_tx_weight(channel_type_features: &ChannelTypeFeatures) -> u64 {
        const HTLC_SUCCESS_TX_WEIGHT: u64 = 703;
        const HTLC_SUCCESS_ANCHOR_TX_WEIGHT: u64 = 706;
-       if opt_anchors { HTLC_SUCCESS_ANCHOR_TX_WEIGHT } else { HTLC_SUCCESS_TX_WEIGHT }
+       if channel_type_features.supports_anchors_zero_fee_htlc_tx() { HTLC_SUCCESS_ANCHOR_TX_WEIGHT } else { HTLC_SUCCESS_TX_WEIGHT }
 }
 
 /// Gets the weight for an HTLC-Timeout transaction.
 #[inline]
-pub fn htlc_timeout_tx_weight(opt_anchors: bool) -> u64 {
+pub fn htlc_timeout_tx_weight(channel_type_features: &ChannelTypeFeatures) -> u64 {
        const HTLC_TIMEOUT_TX_WEIGHT: u64 = 663;
        const HTLC_TIMEOUT_ANCHOR_TX_WEIGHT: u64 = 666;
-       if opt_anchors { HTLC_TIMEOUT_ANCHOR_TX_WEIGHT } else { HTLC_TIMEOUT_TX_WEIGHT }
+       if channel_type_features.supports_anchors_zero_fee_htlc_tx() { HTLC_TIMEOUT_ANCHOR_TX_WEIGHT } else { HTLC_TIMEOUT_TX_WEIGHT }
 }
 
 /// Describes the type of HTLC claim as determined by analyzing the witness.
@@ -584,7 +584,7 @@ impl_writeable_tlv_based!(HTLCOutputInCommitment, {
 });
 
 #[inline]
-pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommitment, opt_anchors: bool, broadcaster_htlc_key: &PublicKey, countersignatory_htlc_key: &PublicKey, revocation_key: &PublicKey) -> Script {
+pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommitment, channel_type_features: &ChannelTypeFeatures, broadcaster_htlc_key: &PublicKey, countersignatory_htlc_key: &PublicKey, revocation_key: &PublicKey) -> Script {
        let payment_hash160 = Ripemd160::hash(&htlc.payment_hash.0[..]).into_inner();
        if htlc.offered {
                let mut bldr = Builder::new().push_opcode(opcodes::all::OP_DUP)
@@ -612,7 +612,7 @@ pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommit
                              .push_opcode(opcodes::all::OP_EQUALVERIFY)
                              .push_opcode(opcodes::all::OP_CHECKSIG)
                              .push_opcode(opcodes::all::OP_ENDIF);
-               if opt_anchors {
+               if channel_type_features.supports_anchors_zero_fee_htlc_tx() {
                        bldr = bldr.push_opcode(opcodes::all::OP_PUSHNUM_1)
                                .push_opcode(opcodes::all::OP_CSV)
                                .push_opcode(opcodes::all::OP_DROP);
@@ -648,7 +648,7 @@ pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommit
                              .push_opcode(opcodes::all::OP_DROP)
                              .push_opcode(opcodes::all::OP_CHECKSIG)
                              .push_opcode(opcodes::all::OP_ENDIF);
-               if opt_anchors {
+               if channel_type_features.supports_anchors_zero_fee_htlc_tx() {
                        bldr = bldr.push_opcode(opcodes::all::OP_PUSHNUM_1)
                                .push_opcode(opcodes::all::OP_CSV)
                                .push_opcode(opcodes::all::OP_DROP);
@@ -661,8 +661,8 @@ pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommit
 /// Gets the witness redeemscript for an HTLC output in a commitment transaction. Note that htlc
 /// does not need to have its previous_output_index filled.
 #[inline]
-pub fn get_htlc_redeemscript(htlc: &HTLCOutputInCommitment, opt_anchors: bool, keys: &TxCreationKeys) -> Script {
-       get_htlc_redeemscript_with_explicit_keys(htlc, opt_anchors, &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key)
+pub fn get_htlc_redeemscript(htlc: &HTLCOutputInCommitment, channel_type_features: &ChannelTypeFeatures, keys: &TxCreationKeys) -> Script {
+       get_htlc_redeemscript_with_explicit_keys(htlc, channel_type_features, &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key)
 }
 
 /// Gets the redeemscript for a funding output from the two funding public keys.
@@ -692,13 +692,13 @@ pub(crate) fn make_funding_redeemscript_from_slices(broadcaster_funding_key: &[u
 ///
 /// 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, use_non_zero_fee_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, channel_type_features: &ChannelTypeFeatures, broadcaster_delayed_payment_key: &PublicKey, revocation_key: &PublicKey) -> Transaction {
        let mut txins: Vec<TxIn> = Vec::new();
-       txins.push(build_htlc_input(commitment_txid, htlc, opt_anchors));
+       txins.push(build_htlc_input(commitment_txid, htlc, channel_type_features));
 
        let mut txouts: Vec<TxOut> = Vec::new();
        txouts.push(build_htlc_output(
-               feerate_per_kw, contest_delay, htlc, opt_anchors, use_non_zero_fee_anchors,
+               feerate_per_kw, contest_delay, htlc, channel_type_features,
                broadcaster_delayed_payment_key, revocation_key
        ));
 
@@ -710,28 +710,27 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
        }
 }
 
-pub(crate) fn build_htlc_input(commitment_txid: &Txid, htlc: &HTLCOutputInCommitment, opt_anchors: bool) -> TxIn {
+pub(crate) fn build_htlc_input(commitment_txid: &Txid, htlc: &HTLCOutputInCommitment, channel_type_features: &ChannelTypeFeatures) -> TxIn {
        TxIn {
                previous_output: OutPoint {
                        txid: commitment_txid.clone(),
                        vout: htlc.transaction_output_index.expect("Can't build an HTLC transaction for a dust output"),
                },
                script_sig: Script::new(),
-               sequence: Sequence(if opt_anchors { 1 } else { 0 }),
+               sequence: Sequence(if channel_type_features.supports_anchors_zero_fee_htlc_tx() { 1 } else { 0 }),
                witness: Witness::new(),
        }
 }
 
 pub(crate) fn build_htlc_output(
-       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
+       feerate_per_kw: u32, contest_delay: u16, htlc: &HTLCOutputInCommitment, channel_type_features: &ChannelTypeFeatures, broadcaster_delayed_payment_key: &PublicKey, revocation_key: &PublicKey
 ) -> TxOut {
        let weight = if htlc.offered {
-               htlc_timeout_tx_weight(opt_anchors)
+               htlc_timeout_tx_weight(channel_type_features)
        } else {
-               htlc_success_tx_weight(opt_anchors)
+               htlc_success_tx_weight(channel_type_features)
        };
-       let output_value = if opt_anchors && !use_non_zero_fee_anchors {
+       let output_value = if channel_type_features.supports_anchors_zero_fee_htlc_tx() && !channel_type_features.supports_anchors_nonzero_fee_htlc_tx() {
                htlc.amount_msat / 1000
        } else {
                let total_fee = feerate_per_kw as u64 * weight / 1000;
@@ -747,9 +746,9 @@ pub(crate) fn build_htlc_output(
 /// Returns the witness required to satisfy and spend a HTLC input.
 pub fn build_htlc_input_witness(
        local_sig: &Signature, remote_sig: &Signature, preimage: &Option<PaymentPreimage>,
-       redeem_script: &Script, opt_anchors: bool,
+       redeem_script: &Script, channel_type_features: &ChannelTypeFeatures,
 ) -> Witness {
-       let remote_sighash_type = if opt_anchors {
+       let remote_sighash_type = if channel_type_features.supports_anchors_zero_fee_htlc_tx() {
                EcdsaSighashType::SinglePlusAnyoneCanPay
        } else {
                EcdsaSighashType::All
@@ -867,13 +866,9 @@ pub struct ChannelTransactionParameters {
        pub counterparty_parameters: Option<CounterpartyChannelTransactionParameters>,
        /// The late-bound funding outpoint
        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<()>,
-       /// 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<()>,
+       /// This channel's type, as negotiated during channel open. For old objects where this field
+       /// wasn't serialized, it will default to static_remote_key at deserialization.
+       pub channel_type_features: ChannelTypeFeatures
 }
 
 /// Late-bound per-channel counterparty data used to build transactions.
@@ -921,15 +916,52 @@ impl_writeable_tlv_based!(CounterpartyChannelTransactionParameters, {
        (2, selected_contest_delay, required),
 });
 
-impl_writeable_tlv_based!(ChannelTransactionParameters, {
-       (0, holder_pubkeys, required),
-       (2, holder_selected_contest_delay, required),
-       (4, is_outbound_from_holder, required),
-       (6, counterparty_parameters, option),
-       (8, funding_outpoint, option),
-       (10, opt_anchors, option),
-       (12, opt_non_zero_fee_anchors, option),
-});
+impl Writeable for ChannelTransactionParameters {
+       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+               let legacy_deserialization_prevention_marker = legacy_deserialization_prevention_marker_for_channel_type_features(&self.channel_type_features);
+               write_tlv_fields!(writer, {
+                       (0, self.holder_pubkeys, required),
+                       (2, self.holder_selected_contest_delay, required),
+                       (4, self.is_outbound_from_holder, required),
+                       (6, self.counterparty_parameters, option),
+                       (8, self.funding_outpoint, option),
+                       (10, legacy_deserialization_prevention_marker, option),
+                       (11, self.channel_type_features, required),
+               });
+               Ok(())
+       }
+}
+
+impl Readable for ChannelTransactionParameters {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+               let mut holder_pubkeys = RequiredWrapper(None);
+               let mut holder_selected_contest_delay = RequiredWrapper(None);
+               let mut is_outbound_from_holder = RequiredWrapper(None);
+               let mut counterparty_parameters = None;
+               let mut funding_outpoint = None;
+               let mut legacy_deserialization_prevention_marker: Option<()> = None;
+               let mut channel_type_features = None;
+
+               read_tlv_fields!(reader, {
+                       (0, holder_pubkeys, required),
+                       (2, holder_selected_contest_delay, required),
+                       (4, is_outbound_from_holder, required),
+                       (6, counterparty_parameters, option),
+                       (8, funding_outpoint, option),
+                       (10, legacy_deserialization_prevention_marker, option),
+                       (11, channel_type_features, option),
+               });
+
+               Ok(Self {
+                       holder_pubkeys: holder_pubkeys.0.unwrap(),
+                       holder_selected_contest_delay: holder_selected_contest_delay.0.unwrap(),
+                       is_outbound_from_holder: is_outbound_from_holder.0.unwrap(),
+                       counterparty_parameters,
+                       funding_outpoint,
+                       channel_type_features: channel_type_features.unwrap_or(ChannelTypeFeatures::only_static_remote_key())
+               })
+       }
+}
 
 /// Static channel fields used to build transactions given per-commitment fields, organized by
 /// broadcaster/countersignatory.
@@ -983,8 +1015,8 @@ impl<'a> DirectedChannelTransactionParameters<'a> {
        }
 
        /// Whether to use anchors for this channel
-       pub fn opt_anchors(&self) -> bool {
-               self.inner.opt_anchors.is_some()
+       pub fn channel_type_features(&self) -> &ChannelTypeFeatures {
+               &self.inner.channel_type_features
        }
 }
 
@@ -1051,14 +1083,13 @@ 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_non_zero_fee_anchors: None,
+                       channel_type_features: ChannelTypeFeatures::only_static_remote_key(),
                };
                let mut counterparty_htlc_sigs = Vec::new();
                for _ in 0..htlcs.len() {
                        counterparty_htlc_sigs.push(dummy_sig);
                }
-               let inner = CommitmentTransaction::new_with_auxiliary_htlc_data(0, 0, 0, false, dummy_key.clone(), dummy_key.clone(), keys, 0, htlcs, &channel_parameters.as_counterparty_broadcastable());
+               let inner = CommitmentTransaction::new_with_auxiliary_htlc_data(0, 0, 0, dummy_key.clone(), dummy_key.clone(), keys, 0, htlcs, &channel_parameters.as_counterparty_broadcastable());
                htlcs.sort_by_key(|htlc| htlc.0.transaction_output_index);
                HolderCommitmentTransaction {
                        inner,
@@ -1276,10 +1307,8 @@ pub struct CommitmentTransaction {
        to_countersignatory_value_sat: u64,
        feerate_per_kw: u32,
        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<()>,
+       // Note that on upgrades, some features of existing outputs may be missed.
+       channel_type_features: ChannelTypeFeatures,
        // 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()
@@ -1294,7 +1323,7 @@ impl PartialEq for CommitmentTransaction {
                        self.to_countersignatory_value_sat == o.to_countersignatory_value_sat &&
                        self.feerate_per_kw == o.feerate_per_kw &&
                        self.htlcs == o.htlcs &&
-                       self.opt_anchors == o.opt_anchors &&
+                       self.channel_type_features == o.channel_type_features &&
                        self.keys == o.keys;
                if eq {
                        debug_assert_eq!(self.built.transaction, o.built.transaction);
@@ -1304,17 +1333,60 @@ impl PartialEq for CommitmentTransaction {
        }
 }
 
-impl_writeable_tlv_based!(CommitmentTransaction, {
-       (0, commitment_number, required),
-       (2, to_broadcaster_value_sat, required),
-       (4, to_countersignatory_value_sat, required),
-       (6, feerate_per_kw, required),
-       (8, keys, required),
-       (10, built, required),
-       (12, htlcs, vec_type),
-       (14, opt_anchors, option),
-       (16, opt_non_zero_fee_anchors, option),
-});
+impl Writeable for CommitmentTransaction {
+       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+               let legacy_deserialization_prevention_marker = legacy_deserialization_prevention_marker_for_channel_type_features(&self.channel_type_features);
+               write_tlv_fields!(writer, {
+                       (0, self.commitment_number, required),
+                       (2, self.to_broadcaster_value_sat, required),
+                       (4, self.to_countersignatory_value_sat, required),
+                       (6, self.feerate_per_kw, required),
+                       (8, self.keys, required),
+                       (10, self.built, required),
+                       (12, self.htlcs, vec_type),
+                       (14, legacy_deserialization_prevention_marker, option),
+                       (15, self.channel_type_features, required),
+               });
+               Ok(())
+       }
+}
+
+impl Readable for CommitmentTransaction {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+               let mut commitment_number = RequiredWrapper(None);
+               let mut to_broadcaster_value_sat = RequiredWrapper(None);
+               let mut to_countersignatory_value_sat = RequiredWrapper(None);
+               let mut feerate_per_kw = RequiredWrapper(None);
+               let mut keys = RequiredWrapper(None);
+               let mut built = RequiredWrapper(None);
+               _init_tlv_field_var!(htlcs, vec_type);
+               let mut legacy_deserialization_prevention_marker: Option<()> = None;
+               let mut channel_type_features = None;
+
+               read_tlv_fields!(reader, {
+                       (0, commitment_number, required),
+                       (2, to_broadcaster_value_sat, required),
+                       (4, to_countersignatory_value_sat, required),
+                       (6, feerate_per_kw, required),
+                       (8, keys, required),
+                       (10, built, required),
+                       (12, htlcs, vec_type),
+                       (14, legacy_deserialization_prevention_marker, option),
+                       (15, channel_type_features, option),
+               });
+
+               Ok(Self {
+                       commitment_number: commitment_number.0.unwrap(),
+                       to_broadcaster_value_sat: to_broadcaster_value_sat.0.unwrap(),
+                       to_countersignatory_value_sat: to_countersignatory_value_sat.0.unwrap(),
+                       feerate_per_kw: feerate_per_kw.0.unwrap(),
+                       keys: keys.0.unwrap(),
+                       built: built.0.unwrap(),
+                       htlcs: _init_tlv_based_struct_field!(htlcs, vec_type),
+                       channel_type_features: channel_type_features.unwrap_or(ChannelTypeFeatures::only_static_remote_key())
+               })
+       }
+}
 
 impl CommitmentTransaction {
        /// Construct an object of the class while assigning transaction output indices to HTLCs.
@@ -1327,9 +1399,9 @@ impl CommitmentTransaction {
        /// Only include HTLCs that are above the dust limit for the channel.
        ///
        /// This is not exported to bindings users due to the generic though we likely should expose a version without
-       pub fn new_with_auxiliary_htlc_data<T>(commitment_number: u64, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, opt_anchors: bool, broadcaster_funding_key: PublicKey, countersignatory_funding_key: PublicKey, keys: TxCreationKeys, feerate_per_kw: u32, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters) -> CommitmentTransaction {
+       pub fn new_with_auxiliary_htlc_data<T>(commitment_number: u64, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, broadcaster_funding_key: PublicKey, countersignatory_funding_key: PublicKey, keys: TxCreationKeys, feerate_per_kw: u32, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters) -> CommitmentTransaction {
                // Sort outputs and populate output indices while keeping track of the auxiliary data
-               let (outputs, htlcs) = Self::internal_build_outputs(&keys, to_broadcaster_value_sat, to_countersignatory_value_sat, htlcs_with_aux, channel_parameters, opt_anchors, &broadcaster_funding_key, &countersignatory_funding_key).unwrap();
+               let (outputs, htlcs) = Self::internal_build_outputs(&keys, to_broadcaster_value_sat, to_countersignatory_value_sat, htlcs_with_aux, channel_parameters, &broadcaster_funding_key, &countersignatory_funding_key).unwrap();
 
                let (obscured_commitment_transaction_number, txins) = Self::internal_build_inputs(commitment_number, channel_parameters);
                let transaction = Self::make_transaction(obscured_commitment_transaction_number, txins, outputs);
@@ -1340,13 +1412,12 @@ impl CommitmentTransaction {
                        to_countersignatory_value_sat,
                        feerate_per_kw,
                        htlcs,
-                       opt_anchors: if opt_anchors { Some(()) } else { None },
+                       channel_type_features: channel_parameters.channel_type_features().clone(),
                        keys,
                        built: BuiltCommitmentTransaction {
                                transaction,
                                txid
                        },
-                       opt_non_zero_fee_anchors: None,
                }
        }
 
@@ -1354,7 +1425,7 @@ impl CommitmentTransaction {
        ///
        /// This is not exported to bindings users 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.channel_type_features.set_anchors_nonzero_fee_htlc_tx_required();
                self
        }
 
@@ -1362,7 +1433,7 @@ impl CommitmentTransaction {
                let (obscured_commitment_transaction_number, txins) = Self::internal_build_inputs(self.commitment_number, channel_parameters);
 
                let mut htlcs_with_aux = self.htlcs.iter().map(|h| (h.clone(), ())).collect();
-               let (outputs, _) = Self::internal_build_outputs(keys, self.to_broadcaster_value_sat, self.to_countersignatory_value_sat, &mut htlcs_with_aux, channel_parameters, self.opt_anchors.is_some(), broadcaster_funding_key, countersignatory_funding_key)?;
+               let (outputs, _) = Self::internal_build_outputs(keys, self.to_broadcaster_value_sat, self.to_countersignatory_value_sat, &mut htlcs_with_aux, channel_parameters, broadcaster_funding_key, countersignatory_funding_key)?;
 
                let transaction = Self::make_transaction(obscured_commitment_transaction_number, txins, outputs);
                let txid = transaction.txid();
@@ -1386,14 +1457,14 @@ impl CommitmentTransaction {
        // - initial sorting of outputs / HTLCs in the constructor, in which case T is auxiliary data the
        //   caller needs to have sorted together with the HTLCs so it can keep track of the output index
        // - building of a bitcoin transaction during a verify() call, in which case T is just ()
-       fn internal_build_outputs<T>(keys: &TxCreationKeys, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters, opt_anchors: bool, broadcaster_funding_key: &PublicKey, countersignatory_funding_key: &PublicKey) -> Result<(Vec<TxOut>, Vec<HTLCOutputInCommitment>), ()> {
+       fn internal_build_outputs<T>(keys: &TxCreationKeys, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters, broadcaster_funding_key: &PublicKey, countersignatory_funding_key: &PublicKey) -> Result<(Vec<TxOut>, Vec<HTLCOutputInCommitment>), ()> {
                let countersignatory_pubkeys = channel_parameters.countersignatory_pubkeys();
                let contest_delay = channel_parameters.contest_delay();
 
                let mut txouts: Vec<(TxOut, Option<&mut HTLCOutputInCommitment>)> = Vec::new();
 
                if to_countersignatory_value_sat > 0 {
-                       let script = if opt_anchors {
+                       let script = if channel_parameters.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
                            get_to_countersignatory_with_anchors_redeemscript(&countersignatory_pubkeys.payment_point).to_v0_p2wsh()
                        } else {
                            Payload::p2wpkh(&BitcoinPublicKey::new(countersignatory_pubkeys.payment_point)).unwrap().script_pubkey()
@@ -1422,7 +1493,7 @@ impl CommitmentTransaction {
                        ));
                }
 
-               if opt_anchors {
+               if channel_parameters.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
                        if to_broadcaster_value_sat > 0 || !htlcs_with_aux.is_empty() {
                                let anchor_script = get_anchor_redeemscript(broadcaster_funding_key);
                                txouts.push((
@@ -1448,7 +1519,7 @@ impl CommitmentTransaction {
 
                let mut htlcs = Vec::with_capacity(htlcs_with_aux.len());
                for (htlc, _) in htlcs_with_aux {
-                       let script = chan_utils::get_htlc_redeemscript(&htlc, opt_anchors, &keys);
+                       let script = chan_utils::get_htlc_redeemscript(&htlc, &channel_parameters.channel_type_features(), &keys);
                        let txout = TxOut {
                                script_pubkey: script.to_v0_p2wsh(),
                                value: htlc.amount_msat / 1000,
@@ -1603,8 +1674,8 @@ impl<'a> TrustedCommitmentTransaction<'a> {
        }
 
        /// Should anchors be used.
-       pub fn opt_anchors(&self) -> bool {
-               self.opt_anchors.is_some()
+       pub fn channel_type_features(&self) -> &ChannelTypeFeatures {
+               &self.inner.channel_type_features
        }
 
        /// Get a signature for each HTLC which was included in the commitment transaction (ie for
@@ -1625,9 +1696,9 @@ 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(), self.opt_non_zero_fee_anchors.is_some(), &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.channel_type_features, &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);
+                       let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, &self.channel_type_features, &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key);
 
                        let sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, EcdsaSighashType::All).unwrap()[..]);
                        ret.push(sign_with_aux_rand(secp_ctx, &sighash, &holder_htlc_key, entropy_source));
@@ -1647,12 +1718,12 @@ 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(), self.opt_non_zero_fee_anchors.is_some(), &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.channel_type_features, &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);
+               let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, &self.channel_type_features, &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key);
 
                htlc_tx.input[0].witness = chan_utils::build_htlc_input_witness(
-                       signature, counterparty_signature, preimage, &htlc_redeemscript, self.opt_anchors(),
+                       signature, counterparty_signature, preimage, &htlc_redeemscript, &self.channel_type_features,
                );
                htlc_tx
        }
@@ -1703,6 +1774,7 @@ mod tests {
        use bitcoin::hashes::hex::ToHex;
        use bitcoin::util::address::Payload;
        use bitcoin::PublicKey as BitcoinPublicKey;
+       use crate::ln::features::ChannelTypeFeatures;
 
        #[test]
        fn test_anchors() {
@@ -1726,8 +1798,7 @@ 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_non_zero_fee_anchors: None,
+                       channel_type_features: ChannelTypeFeatures::only_static_remote_key(),
                };
 
                let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();
@@ -1735,7 +1806,6 @@ mod tests {
                // Generate broadcaster and counterparty outputs
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
                        0, 1000, 2000,
-                       false,
                        holder_pubkeys.funding_pubkey,
                        counterparty_pubkeys.funding_pubkey,
                        keys.clone(), 1,
@@ -1745,9 +1815,9 @@ mod tests {
                assert_eq!(tx.built.transaction.output[1].script_pubkey, Payload::p2wpkh(&BitcoinPublicKey::new(counterparty_pubkeys.payment_point)).unwrap().script_pubkey());
 
                // Generate broadcaster and counterparty outputs as well as two anchors
+               channel_parameters.channel_type_features = ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies();
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
                        0, 1000, 2000,
-                       true,
                        holder_pubkeys.funding_pubkey,
                        counterparty_pubkeys.funding_pubkey,
                        keys.clone(), 1,
@@ -1759,7 +1829,6 @@ mod tests {
                // Generate broadcaster output and anchor
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
                        0, 3000, 0,
-                       true,
                        holder_pubkeys.funding_pubkey,
                        counterparty_pubkeys.funding_pubkey,
                        keys.clone(), 1,
@@ -1770,7 +1839,6 @@ mod tests {
                // Generate counterparty output and anchor
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
                        0, 0, 3000,
-                       true,
                        holder_pubkeys.funding_pubkey,
                        counterparty_pubkeys.funding_pubkey,
                        keys.clone(), 1,
@@ -1795,9 +1863,9 @@ mod tests {
                };
 
                // Generate broadcaster output and received and offered HTLC outputs,  w/o anchors
+               channel_parameters.channel_type_features = ChannelTypeFeatures::only_static_remote_key();
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
                        0, 3000, 0,
-                       false,
                        holder_pubkeys.funding_pubkey,
                        counterparty_pubkeys.funding_pubkey,
                        keys.clone(), 1,
@@ -1805,18 +1873,17 @@ mod tests {
                        &channel_parameters.as_holder_broadcastable()
                );
                assert_eq!(tx.built.transaction.output.len(), 3);
-               assert_eq!(tx.built.transaction.output[0].script_pubkey, get_htlc_redeemscript(&received_htlc, false, &keys).to_v0_p2wsh());
-               assert_eq!(tx.built.transaction.output[1].script_pubkey, get_htlc_redeemscript(&offered_htlc, false, &keys).to_v0_p2wsh());
-               assert_eq!(get_htlc_redeemscript(&received_htlc, false, &keys).to_v0_p2wsh().to_hex(),
+               assert_eq!(tx.built.transaction.output[0].script_pubkey, get_htlc_redeemscript(&received_htlc, &ChannelTypeFeatures::only_static_remote_key(), &keys).to_v0_p2wsh());
+               assert_eq!(tx.built.transaction.output[1].script_pubkey, get_htlc_redeemscript(&offered_htlc, &ChannelTypeFeatures::only_static_remote_key(), &keys).to_v0_p2wsh());
+               assert_eq!(get_htlc_redeemscript(&received_htlc, &ChannelTypeFeatures::only_static_remote_key(), &keys).to_v0_p2wsh().to_hex(),
                                   "0020e43a7c068553003fe68fcae424fb7b28ec5ce48cd8b6744b3945631389bad2fb");
-               assert_eq!(get_htlc_redeemscript(&offered_htlc, false, &keys).to_v0_p2wsh().to_hex(),
+               assert_eq!(get_htlc_redeemscript(&offered_htlc, &ChannelTypeFeatures::only_static_remote_key(), &keys).to_v0_p2wsh().to_hex(),
                                   "0020215d61bba56b19e9eadb6107f5a85d7f99c40f65992443f69229c290165bc00d");
 
                // Generate broadcaster output and received and offered HTLC outputs,  with anchors
-               channel_parameters.opt_anchors = Some(());
+               channel_parameters.channel_type_features = ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies();
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
                        0, 3000, 0,
-                       true,
                        holder_pubkeys.funding_pubkey,
                        counterparty_pubkeys.funding_pubkey,
                        keys.clone(), 1,
@@ -1824,11 +1891,11 @@ mod tests {
                        &channel_parameters.as_holder_broadcastable()
                );
                assert_eq!(tx.built.transaction.output.len(), 5);
-               assert_eq!(tx.built.transaction.output[2].script_pubkey, get_htlc_redeemscript(&received_htlc, true, &keys).to_v0_p2wsh());
-               assert_eq!(tx.built.transaction.output[3].script_pubkey, get_htlc_redeemscript(&offered_htlc, true, &keys).to_v0_p2wsh());
-               assert_eq!(get_htlc_redeemscript(&received_htlc, true, &keys).to_v0_p2wsh().to_hex(),
+               assert_eq!(tx.built.transaction.output[2].script_pubkey, get_htlc_redeemscript(&received_htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &keys).to_v0_p2wsh());
+               assert_eq!(tx.built.transaction.output[3].script_pubkey, get_htlc_redeemscript(&offered_htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &keys).to_v0_p2wsh());
+               assert_eq!(get_htlc_redeemscript(&received_htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &keys).to_v0_p2wsh().to_hex(),
                                   "0020b70d0649c72b38756885c7a30908d912a7898dd5d79457a7280b8e9a20f3f2bc");
-               assert_eq!(get_htlc_redeemscript(&offered_htlc, true, &keys).to_v0_p2wsh().to_hex(),
+               assert_eq!(get_htlc_redeemscript(&offered_htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &keys).to_v0_p2wsh().to_hex(),
                                   "002087a3faeb1950a469c0e2db4a79b093a41b9526e5a6fc6ef5cb949bde3be379c7");
        }