Merge pull request #1828 from lightning-signer/2022-11-non-zero-fee-anchors
[rust-lightning] / lightning / src / ln / chan_utils.rs
index df0378938b42eeb0b1ff0fbd1413f6f140617a12..3a6e81e6399c804bed7fac94a8526ddef809e7df 100644 (file)
@@ -20,10 +20,10 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hashes::ripemd160::Hash as Ripemd160;
 use bitcoin::hash_types::{Txid, PubkeyHash};
 
-use ln::{PaymentHash, PaymentPreimage};
-use ln::msgs::DecodeError;
-use util::ser::{Readable, Writeable, Writer};
-use util::{byte_utils, transaction_utils};
+use crate::ln::{PaymentHash, PaymentPreimage};
+use crate::ln::msgs::DecodeError;
+use crate::util::ser::{Readable, Writeable, Writer};
+use crate::util::{byte_utils, transaction_utils};
 
 use bitcoin::hash_types::WPubkeyHash;
 use bitcoin::secp256k1::{SecretKey, PublicKey, Scalar};
@@ -31,15 +31,15 @@ use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature, Message};
 use bitcoin::secp256k1::Error as SecpError;
 use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness};
 
-use io;
-use prelude::*;
+use crate::io;
+use crate::prelude::*;
 use core::cmp;
-use ln::chan_utils;
-use util::transaction_utils::sort_outputs;
-use ln::channel::{INITIAL_COMMITMENT_NUMBER, ANCHOR_OUTPUT_VALUE_SATOSHI};
+use crate::ln::chan_utils;
+use crate::util::transaction_utils::sort_outputs;
+use crate::ln::channel::{INITIAL_COMMITMENT_NUMBER, ANCHOR_OUTPUT_VALUE_SATOSHI};
 use core::ops::Deref;
-use chain;
-use util::crypto::sign;
+use crate::chain;
+use crate::util::crypto::sign;
 
 pub(crate) const MAX_HTLCS: u16 = 483;
 pub(crate) const OFFERED_HTLC_SCRIPT_WEIGHT: usize = 133;
@@ -65,7 +65,7 @@ pub fn htlc_timeout_tx_weight(opt_anchors: bool) -> u64 {
        if opt_anchors { HTLC_TIMEOUT_ANCHOR_TX_WEIGHT } else { HTLC_TIMEOUT_TX_WEIGHT }
 }
 
-#[derive(PartialEq)]
+#[derive(PartialEq, Eq)]
 pub(crate) enum HTLCClaim {
        OfferedTimeout,
        OfferedPreimage,
@@ -208,6 +208,7 @@ pub struct CounterpartyCommitmentSecrets {
        old_secrets: [([u8; 32], u64); 49],
 }
 
+impl Eq for CounterpartyCommitmentSecrets {}
 impl PartialEq for CounterpartyCommitmentSecrets {
        fn eq(&self, other: &Self) -> bool {
                for (&(ref secret, ref idx), &(ref o_secret, ref o_idx)) in self.old_secrets.iter().zip(other.old_secrets.iter()) {
@@ -419,7 +420,7 @@ pub fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp2
 /// channel basepoints via the new function, or they were obtained via
 /// CommitmentTransaction.trust().keys() because we trusted the source of the
 /// pre-calculated keys.
-#[derive(PartialEq, Clone)]
+#[derive(PartialEq, Eq, Clone)]
 pub struct TxCreationKeys {
        /// The broadcaster's per-commitment public key which was used to derive the other keys.
        pub per_commitment_point: PublicKey,
@@ -444,7 +445,7 @@ impl_writeable_tlv_based!(TxCreationKeys, {
 });
 
 /// One counterparty's public keys which do not change over the life of a channel.
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct ChannelPublicKeys {
        /// The public key which is used to sign all commitment transactions, as it appears in the
        /// on-chain channel lock-in 2-of-2 multisig output.
@@ -525,8 +526,8 @@ pub fn get_revokeable_redeemscript(revocation_key: &PublicKey, contest_delay: u1
        res
 }
 
-#[derive(Clone, PartialEq)]
 /// Information about an HTLC as it appears in a commitment transaction
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct HTLCOutputInCommitment {
        /// Whether the HTLC was "offered" (ie outbound in relation to this commitment transaction).
        /// Note that this is not the same as whether it is ountbound *from us*. To determine that you
@@ -659,7 +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 {
@@ -676,7 +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;
@@ -726,6 +727,23 @@ pub fn get_anchor_redeemscript(funding_pubkey: &PublicKey) -> Script {
                .into_script()
 }
 
+#[cfg(anchors)]
+/// Locates the output with an anchor script paying to `funding_pubkey` within `commitment_tx`.
+pub(crate) fn get_anchor_output<'a>(commitment_tx: &'a Transaction, funding_pubkey: &PublicKey) -> Option<(u32, &'a TxOut)> {
+       let anchor_script = chan_utils::get_anchor_redeemscript(funding_pubkey).to_v0_p2wsh();
+       commitment_tx.output.iter().enumerate()
+               .find(|(_, txout)| txout.script_pubkey == anchor_script)
+               .map(|(idx, txout)| (idx as u32, txout))
+}
+
+/// Returns the witness required to satisfy and spend an anchor input.
+pub fn build_anchor_input_witness(funding_key: &PublicKey, funding_sig: &Signature) -> Witness {
+       let anchor_redeem_script = chan_utils::get_anchor_redeemscript(funding_key);
+       let mut funding_sig = funding_sig.serialize_der().to_vec();
+       funding_sig.push(EcdsaSighashType::All as u8);
+       Witness::from_vec(vec![funding_sig, anchor_redeem_script.to_bytes()])
+}
+
 /// Per-channel data used to build transactions in conjunction with the per-commitment data (CommitmentTransaction).
 /// The fields are organized by holder/counterparty.
 ///
@@ -747,7 +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.
@@ -802,6 +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
@@ -882,6 +905,7 @@ impl Deref for HolderCommitmentTransaction {
        fn deref(&self) -> &Self::Target { &self.inner }
 }
 
+impl Eq for HolderCommitmentTransaction {}
 impl PartialEq for HolderCommitmentTransaction {
        // We dont care whether we are signed in equality comparison
        fn eq(&self, o: &Self) -> bool {
@@ -923,7 +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());
@@ -1007,7 +1032,7 @@ impl BuiltCommitmentTransaction {
 ///
 /// This class can be used inside a signer implementation to generate a signature given the relevant
 /// secret key.
-#[derive(Clone, Hash, PartialEq)]
+#[derive(Clone, Hash, PartialEq, Eq)]
 pub struct ClosingTransaction {
        to_holder_value_sat: u64,
        to_counterparty_value_sat: u64,
@@ -1141,12 +1166,15 @@ 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()
        built: BuiltCommitmentTransaction,
 }
 
+impl Eq for CommitmentTransaction {}
 impl PartialEq for CommitmentTransaction {
        fn eq(&self, o: &Self) -> bool {
                let eq = self.commitment_number == o.commitment_number &&
@@ -1173,6 +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 {
@@ -1205,9 +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);
 
@@ -1472,7 +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);
 
@@ -1494,7 +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);
 
@@ -1561,15 +1599,15 @@ fn get_p2wpkh_redeemscript(key: &PublicKey) -> Script {
 #[cfg(test)]
 mod tests {
        use super::CounterpartyCommitmentSecrets;
-       use ::{hex, chain};
-       use prelude::*;
-       use ln::chan_utils::{get_htlc_redeemscript, get_to_countersignatory_with_anchors_redeemscript, get_p2wpkh_redeemscript, CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
+       use crate::{hex, chain};
+       use crate::prelude::*;
+       use crate::ln::chan_utils::{get_htlc_redeemscript, get_to_countersignatory_with_anchors_redeemscript, get_p2wpkh_redeemscript, CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
        use bitcoin::secp256k1::{PublicKey, SecretKey, Secp256k1};
-       use util::test_utils;
-       use chain::keysinterface::{KeysInterface, BaseSign};
+       use crate::util::test_utils;
+       use crate::chain::keysinterface::{KeysInterface, BaseSign};
        use bitcoin::{Network, Txid};
        use bitcoin::hashes::Hash;
-       use ln::PaymentHash;
+       use crate::ln::PaymentHash;
        use bitcoin::hashes::hex::ToHex;
 
        #[test]
@@ -1594,7 +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();