Merge pull request #1176 from lightning-signer/2021-11-htlc-anchors
[rust-lightning] / lightning / src / ln / chan_utils.rs
index 9be58a9cc894e2ec04500e6a75518b6ee92dbe1e..ef106cc195ab80780d72d070219060e42d7136a1 100644 (file)
@@ -45,6 +45,20 @@ pub(crate) const MAX_HTLCS: u16 = 483;
 pub(super) const HTLC_SUCCESS_TX_WEIGHT: u64 = 703;
 pub(super) const HTLC_TIMEOUT_TX_WEIGHT: u64 = 663;
 
+/// Gets the weight for an HTLC-Success transaction.
+#[inline]
+pub fn htlc_success_tx_weight(opt_anchors: bool) -> u64 {
+       const HTLC_SUCCESS_ANCHOR_TX_WEIGHT: u64 = 706;
+       if opt_anchors { 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 {
+       const HTLC_TIMEOUT_ANCHOR_TX_WEIGHT: u64 = 666;
+       if opt_anchors { HTLC_TIMEOUT_ANCHOR_TX_WEIGHT } else { HTLC_TIMEOUT_TX_WEIGHT }
+}
+
 #[derive(PartialEq)]
 pub(crate) enum HTLCType {
        AcceptedHTLC,
@@ -482,10 +496,10 @@ impl_writeable_tlv_based!(HTLCOutputInCommitment, {
 });
 
 #[inline]
-pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommitment, broadcaster_htlc_key: &PublicKey, countersignatory_htlc_key: &PublicKey, revocation_key: &PublicKey) -> Script {
+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 {
        let payment_hash160 = Ripemd160::hash(&htlc.payment_hash.0[..]).into_inner();
        if htlc.offered {
-               Builder::new().push_opcode(opcodes::all::OP_DUP)
+               let mut bldr = Builder::new().push_opcode(opcodes::all::OP_DUP)
                              .push_opcode(opcodes::all::OP_HASH160)
                              .push_slice(&PubkeyHash::hash(&revocation_key.serialize())[..])
                              .push_opcode(opcodes::all::OP_EQUAL)
@@ -509,11 +523,16 @@ pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommit
                              .push_slice(&payment_hash160)
                              .push_opcode(opcodes::all::OP_EQUALVERIFY)
                              .push_opcode(opcodes::all::OP_CHECKSIG)
-                             .push_opcode(opcodes::all::OP_ENDIF)
-                             .push_opcode(opcodes::all::OP_ENDIF)
-                             .into_script()
+                             .push_opcode(opcodes::all::OP_ENDIF);
+               if opt_anchors {
+                       bldr = bldr.push_opcode(opcodes::all::OP_PUSHNUM_1)
+                               .push_opcode(opcodes::all::OP_CSV)
+                               .push_opcode(opcodes::all::OP_DROP);
+               }
+               bldr.push_opcode(opcodes::all::OP_ENDIF)
+                       .into_script()
        } else {
-               Builder::new().push_opcode(opcodes::all::OP_DUP)
+                       let mut bldr = Builder::new().push_opcode(opcodes::all::OP_DUP)
                              .push_opcode(opcodes::all::OP_HASH160)
                              .push_slice(&PubkeyHash::hash(&revocation_key.serialize())[..])
                              .push_opcode(opcodes::all::OP_EQUAL)
@@ -540,17 +559,22 @@ pub(crate) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommit
                              .push_opcode(opcodes::all::OP_CLTV)
                              .push_opcode(opcodes::all::OP_DROP)
                              .push_opcode(opcodes::all::OP_CHECKSIG)
-                             .push_opcode(opcodes::all::OP_ENDIF)
-                             .push_opcode(opcodes::all::OP_ENDIF)
-                             .into_script()
+                             .push_opcode(opcodes::all::OP_ENDIF);
+               if opt_anchors {
+                       bldr = bldr.push_opcode(opcodes::all::OP_PUSHNUM_1)
+                               .push_opcode(opcodes::all::OP_CSV)
+                               .push_opcode(opcodes::all::OP_DROP);
+               }
+               bldr.push_opcode(opcodes::all::OP_ENDIF)
+                       .into_script()
        }
 }
 
 /// 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, keys: &TxCreationKeys) -> Script {
-       get_htlc_redeemscript_with_explicit_keys(htlc, &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key)
+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)
 }
 
 /// Gets the redeemscript for a funding output from the two funding public keys.
@@ -576,7 +600,7 @@ 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, 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, broadcaster_delayed_payment_key: &PublicKey, revocation_key: &PublicKey) -> Transaction {
        let mut txins: Vec<TxIn> = Vec::new();
        txins.push(TxIn {
                previous_output: OutPoint {
@@ -584,15 +608,16 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
                        vout: htlc.transaction_output_index.expect("Can't build an HTLC transaction for a dust output"),
                },
                script_sig: Script::new(),
-               sequence: 0,
+               sequence: if opt_anchors { 1 } else { 0 },
                witness: Vec::new(),
        });
 
-       let total_fee = if htlc.offered {
-                       feerate_per_kw as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000
-               } else {
-                       feerate_per_kw as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000
-               };
+       let weight = if htlc.offered {
+               htlc_timeout_tx_weight(opt_anchors)
+       } else {
+               htlc_success_tx_weight(opt_anchors)
+       };
+       let total_fee = feerate_per_kw as u64 * weight / 1000;
 
        let mut txouts: Vec<TxOut> = Vec::new();
        txouts.push(TxOut {
@@ -626,7 +651,7 @@ pub(crate) fn get_to_countersignatory_with_anchors_redeemscript(payment_point: &
 /// <>
 /// (empty vector required to satisfy compliance with MINIMALIF-standard rule)
 #[inline]
-pub(crate) fn get_anchor_redeemscript(funding_pubkey: &PublicKey) -> Script {
+pub fn get_anchor_redeemscript(funding_pubkey: &PublicKey) -> Script {
        Builder::new().push_slice(&funding_pubkey.serialize()[..])
                .push_opcode(opcodes::all::OP_CHECKSIG)
                .push_opcode(opcodes::all::OP_IFDUP)
@@ -656,6 +681,8 @@ pub struct ChannelTransactionParameters {
        pub counterparty_parameters: Option<CounterpartyChannelTransactionParameters>,
        /// The late-bound funding outpoint
        pub funding_outpoint: Option<chain::transaction::OutPoint>,
+       /// Are anchors used for this channel.  Boolean is serialization backwards-compatible
+       pub opt_anchors: Option<()>
 }
 
 /// Late-bound per-channel counterparty data used to build transactions.
@@ -709,6 +736,7 @@ impl_writeable_tlv_based!(ChannelTransactionParameters, {
        (4, is_outbound_from_holder, required),
        (6, counterparty_parameters, option),
        (8, funding_outpoint, option),
+       (10, opt_anchors, option),
 });
 
 /// Static channel fields used to build transactions given per-commitment fields, organized by
@@ -761,6 +789,11 @@ impl<'a> DirectedChannelTransactionParameters<'a> {
        pub fn funding_outpoint(&self) -> OutPoint {
                self.inner.funding_outpoint.unwrap().into_bitcoin_outpoint()
        }
+
+       /// Whether to use anchors for this channel
+       pub fn opt_anchors(&self) -> bool {
+               self.inner.opt_anchors.is_some()
+       }
 }
 
 /// Information needed to build and sign a holder's commitment transaction.
@@ -824,7 +857,8 @@ impl HolderCommitmentTransaction {
                        holder_selected_contest_delay: 0,
                        is_outbound_from_holder: false,
                        counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: channel_pubkeys.clone(), selected_contest_delay: 0 }),
-                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 })
+                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 }),
+                       opt_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());
@@ -1196,7 +1230,7 @@ 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, &keys);
+                       let script = chan_utils::get_htlc_redeemscript(&htlc, opt_anchors, &keys);
                        let txout = TxOut {
                                script_pubkey: script.to_v0_p2wsh(),
                                value: htlc.amount_msat / 1000,
@@ -1350,6 +1384,11 @@ impl<'a> TrustedCommitmentTransaction<'a> {
                &self.inner.keys
        }
 
+       /// Should anchors be used.
+       pub fn opt_anchors(&self) -> bool {
+               self.opt_anchors.is_some()
+       }
+
        /// Get a signature for each HTLC which was included in the commitment transaction (ie for
        /// which HTLCOutputInCommitment::transaction_output_index.is_some()).
        ///
@@ -1363,9 +1402,9 @@ 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, &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(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
-                       let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_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 sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]);
                        ret.push(secp_ctx.sign(&sighash, &holder_htlc_key));
@@ -1385,9 +1424,9 @@ 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, &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(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
-               let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_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);
 
                // First push the multisig dummy, note that due to BIP147 (NULLDUMMY) it must be a zero-length element.
                htlc_tx.input[0].witness.push(Vec::new());
@@ -1450,12 +1489,13 @@ mod tests {
        use super::CounterpartyCommitmentSecrets;
        use ::{hex, chain};
        use prelude::*;
-       use ln::chan_utils::{get_to_countersignatory_with_anchors_redeemscript, get_p2wpkh_redeemscript, CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
+       use 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 bitcoin::Network;
        use ln::PaymentHash;
+       use bitcoin::hashes::hex::ToHex;
 
        #[test]
        fn test_anchors() {
@@ -1473,12 +1513,13 @@ mod tests {
                let holder_pubkeys = signer.pubkeys();
                let counterparty_pubkeys = counterparty_signer.pubkeys();
                let keys = TxCreationKeys::derive_new(&secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint).unwrap();
-               let channel_parameters = ChannelTransactionParameters {
+               let mut channel_parameters = ChannelTransactionParameters {
                        holder_pubkeys: holder_pubkeys.clone(),
                        holder_selected_contest_delay: 0,
                        is_outbound_from_holder: false,
                        counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: counterparty_pubkeys.clone(), selected_contest_delay: 0 }),
-                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 })
+                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 }),
+                       opt_anchors: None
                };
 
                let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();
@@ -1529,25 +1570,58 @@ mod tests {
                );
                assert_eq!(tx.built.transaction.output.len(), 2);
 
-               // Generate broadcaster output, an HTLC output and two anchors
-               let payment_hash = PaymentHash([42; 32]);
-               let htlc_info = HTLCOutputInCommitment {
+               let received_htlc = HTLCOutputInCommitment {
                        offered: false,
-                       amount_msat: 1000000,
+                       amount_msat: 400000,
+                       cltv_expiry: 100,
+                       payment_hash: PaymentHash([42; 32]),
+                       transaction_output_index: None,
+               };
+
+               let offered_htlc = HTLCOutputInCommitment {
+                       offered: true,
+                       amount_msat: 600000,
                        cltv_expiry: 100,
-                       payment_hash,
+                       payment_hash: PaymentHash([43; 32]),
                        transaction_output_index: None,
                };
 
+               // Generate broadcaster output and received and offered HTLC outputs,  w/o anchors
+               let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
+                       0, 3000, 0,
+                       false,
+                       holder_pubkeys.funding_pubkey,
+                       counterparty_pubkeys.funding_pubkey,
+                       keys.clone(), 1,
+                       &mut vec![(received_htlc.clone(), ()), (offered_htlc.clone(), ())],
+                       &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(),
+                                  "002085cf52e41ba7c099a39df504e7b61f6de122971ceb53b06731876eaeb85e8dc5");
+               assert_eq!(get_htlc_redeemscript(&offered_htlc, false, &keys).to_v0_p2wsh().to_hex(),
+                                  "002049f0736bb335c61a04d2623a24df878a7592a3c51fa7258d41b2c85318265e73");
+
+               // Generate broadcaster output and received and offered HTLC outputs,  with anchors
+               channel_parameters.opt_anchors = Some(());
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
                        0, 3000, 0,
                        true,
                        holder_pubkeys.funding_pubkey,
                        counterparty_pubkeys.funding_pubkey,
                        keys.clone(), 1,
-                       &mut vec![(htlc_info, ())], &channel_parameters.as_holder_broadcastable()
+                       &mut vec![(received_htlc.clone(), ()), (offered_htlc.clone(), ())],
+                       &channel_parameters.as_holder_broadcastable()
                );
-               assert_eq!(tx.built.transaction.output.len(), 4);
+               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(),
+                                  "002067114123af3f95405bae4fd930fc95de03e3c86baaee8b2dd29b43dd26cf613c");
+               assert_eq!(get_htlc_redeemscript(&offered_htlc, true, &keys).to_v0_p2wsh().to_hex(),
+                                  "0020a06e3b0d4fcf704f2b9c41e16a70099e39989466c3142b8573a1154542f28f57");
        }
 
        #[test]