Remove signing htlc transaction from ChannelMonitor

[rust-lightning] / lightning / src / chain / keysinterface.rs

diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs
index 5f1a307bf27dc9f7bba705961b8b3646b4393b12..e3e2d929447b129cd4e9664b7d54a1b7c15bea70 100644 (file)
--- a/lightning/src/chain/keysinterface.rs
+++ b/lightning/src/chain/keysinterface.rs
@@ -2,7 +2,7 @@
 //! spendable on-chain outputs which the user owns and is responsible for using just as any other
 //! on-chain output which is theirs.
 
-use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut};
+use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut, SigHashType};
 use bitcoin::blockdata::script::{Script, Builder};
 use bitcoin::blockdata::opcodes;
 use bitcoin::network::constants::Network;
@@ -25,6 +25,7 @@ use util::ser::{Writeable, Writer, Readable};
 
 use ln::chan_utils;
 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, LocalCommitmentTransaction};
+use ln::channelmanager::PaymentPreimage;
 use ln::msgs;
 
 use std::sync::Arc;
@@ -231,6 +232,11 @@ pub trait ChannelKeys : Send+Clone {
        #[cfg(test)]
        fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &mut LocalCommitmentTransaction, funding_redeemscript: &Script, channel_value_satoshis: u64, secp_ctx: &Secp256k1<T>);
 
+       /// Signs a transaction created by build_htlc_transaction. If the transaction is an
+       /// HTLC-Success transaction, preimage must be set!
+       /// TODO: should be merged with sign_local_commitment as a slice of HTLC transactions to sign
+       fn sign_htlc_transaction<T: secp256k1::Signing>(&self, htlc_tx: &mut Transaction, their_sig: &Signature, preimage: &Option<PaymentPreimage>, htlc: &HTLCOutputInCommitment, a_htlc_key: &PublicKey, b_htlc_key: &PublicKey, revocation_key: &PublicKey, per_commitment_point: &PublicKey, secp_ctx: &Secp256k1<T>);
+
        /// Create a signature for a (proposed) closing transaction.
        ///
        /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
@@ -367,6 +373,40 @@ impl ChannelKeys for InMemoryChannelKeys {
                local_commitment_tx.add_local_sig(&self.funding_key, funding_redeemscript, channel_value_satoshis, secp_ctx);
        }
 
+       fn sign_htlc_transaction<T: secp256k1::Signing>(&self, htlc_tx: &mut Transaction, their_sig: &Signature, preimage: &Option<PaymentPreimage>, htlc: &HTLCOutputInCommitment, a_htlc_key: &PublicKey, b_htlc_key: &PublicKey, revocation_key: &PublicKey, per_commitment_point: &PublicKey, secp_ctx: &Secp256k1<T>) {
+               if htlc_tx.input.len() != 1 { return; }
+               if htlc_tx.input[0].witness.len() != 0 { return; }
+
+               let htlc_redeemscript = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, a_htlc_key, b_htlc_key, revocation_key);
+
+               if let Ok(our_htlc_key) = chan_utils::derive_private_key(secp_ctx, per_commitment_point, &self.htlc_base_key) {
+                       let sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
+                       let local_tx = PublicKey::from_secret_key(&secp_ctx, &our_htlc_key) == *a_htlc_key;
+                       let our_sig = secp_ctx.sign(&sighash, &our_htlc_key);
+
+                       htlc_tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
+
+                       if local_tx { // b, then a
+                               htlc_tx.input[0].witness.push(their_sig.serialize_der().to_vec());
+                               htlc_tx.input[0].witness.push(our_sig.serialize_der().to_vec());
+                       } else {
+                               htlc_tx.input[0].witness.push(our_sig.serialize_der().to_vec());
+                               htlc_tx.input[0].witness.push(their_sig.serialize_der().to_vec());
+                       }
+                       htlc_tx.input[0].witness[1].push(SigHashType::All as u8);
+                       htlc_tx.input[0].witness[2].push(SigHashType::All as u8);
+
+                       if htlc.offered {
+                               htlc_tx.input[0].witness.push(Vec::new());
+                               assert!(preimage.is_none());
+                       } else {
+                               htlc_tx.input[0].witness.push(preimage.unwrap().0.to_vec());
+                       }
+
+                       htlc_tx.input[0].witness.push(htlc_redeemscript.as_bytes().to_vec());
+               } else { return; }
+       }
+
        fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
                if closing_tx.input.len() != 1 { return Err(()); }
                if closing_tx.input[0].witness.len() != 0 { return Err(()); }