Build witness_script for remote htlc transactions inside
authorAntoine Riard <ariard@student.42.fr>
Tue, 24 Mar 2020 18:47:37 +0000 (14:47 -0400)
committerAntoine Riard <ariard@student.42.fr>
Sat, 9 May 2020 00:47:06 +0000 (20:47 -0400)
OnchainTxHandler

By moving script generation inside OnchainTxHandler, we may dry-up
further ChannelMonitor in next commits

Comment MINIMALIF rule

lightning/src/ln/channelmonitor.rs
lightning/src/ln/onchaintx.rs

index fc1c5e826a1d2ed3be91e279ae9777a71733b0ae..d35dbdab9d45ffcb5eca2862daa70b0977f435f1 100644 (file)
@@ -430,7 +430,7 @@ pub(crate) enum InputMaterial {
                amount: u64,
        },
        RemoteHTLC {
-               witness_script: Script,
+               per_commitment_point: PublicKey,
                key: SecretKey,
                preimage: Option<PaymentPreimage>,
                amount: u64,
@@ -455,9 +455,9 @@ impl Writeable for InputMaterial  {
                                input_descriptor.write(writer)?;
                                writer.write_all(&byte_utils::be64_to_array(*amount))?;
                        },
-                       &InputMaterial::RemoteHTLC { ref witness_script, ref key, ref preimage, ref amount, ref locktime } => {
+                       &InputMaterial::RemoteHTLC { ref per_commitment_point, ref key, ref preimage, ref amount, ref locktime } => {
                                writer.write_all(&[1; 1])?;
-                               witness_script.write(writer)?;
+                               per_commitment_point.write(writer)?;
                                key.write(writer)?;
                                preimage.write(writer)?;
                                writer.write_all(&byte_utils::be64_to_array(*amount))?;
@@ -493,13 +493,13 @@ impl Readable for InputMaterial {
                                }
                        },
                        1 => {
-                               let witness_script = Readable::read(reader)?;
+                               let per_commitment_point = Readable::read(reader)?;
                                let key = Readable::read(reader)?;
                                let preimage = Readable::read(reader)?;
                                let amount = Readable::read(reader)?;
                                let locktime = Readable::read(reader)?;
                                InputMaterial::RemoteHTLC {
-                                       witness_script,
+                                       per_commitment_point,
                                        key,
                                        preimage,
                                        amount,
@@ -1556,24 +1556,26 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                                                if revocation_points.0 == commitment_number + 1 { Some(point) } else { None }
                                        } else { None };
                                if let Some(revocation_point) = revocation_point_option {
-                                       let revocation_pubkey = ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, revocation_point, &self.keys.pubkeys().revocation_basepoint));
-                                       let b_htlc_key = ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, revocation_point, &self.keys.pubkeys().htlc_basepoint));
                                        let htlc_privkey = ignore_error!(chan_utils::derive_private_key(&self.secp_ctx, revocation_point, &self.keys.htlc_base_key()));
-                                       let a_htlc_key = ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, revocation_point, &self.their_htlc_base_key));
+
+                                       self.remote_payment_script = {
+                                               // Note that the Network here is ignored as we immediately drop the address for the
+                                               // script_pubkey version
+                                               let payment_hash160 = WPubkeyHash::hash(&PublicKey::from_secret_key(&self.secp_ctx, &self.keys.payment_key()).serialize());
+                                               Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&payment_hash160[..]).into_script()
+                                       };
 
                                        // Then, try to find htlc outputs
                                        for (_, &(ref htlc, _)) in per_commitment_data.iter().enumerate() {
                                                if let Some(transaction_output_index) = htlc.transaction_output_index {
-                                                       let expected_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &a_htlc_key, &b_htlc_key, &revocation_pubkey);
                                                        if transaction_output_index as usize >= tx.output.len() ||
-                                                                       tx.output[transaction_output_index as usize].value != htlc.amount_msat / 1000 ||
-                                                                       tx.output[transaction_output_index as usize].script_pubkey != expected_script.to_v0_p2wsh() {
+                                                                       tx.output[transaction_output_index as usize].value != htlc.amount_msat / 1000 {
                                                                return (claimable_outpoints, (commitment_txid, watch_outputs)); // Corrupted per_commitment_data, fuck this user
                                                        }
                                                        let preimage = if htlc.offered { if let Some(p) = self.payment_preimages.get(&htlc.payment_hash) { Some(*p) } else { None } } else { None };
                                                        let aggregable = if !htlc.offered { false } else { true };
                                                        if preimage.is_some() || !htlc.offered {
-                                                               let witness_data = InputMaterial::RemoteHTLC { witness_script: expected_script, key: htlc_privkey, preimage, amount: htlc.amount_msat / 1000, locktime: htlc.cltv_expiry };
+                                                               let witness_data = InputMaterial::RemoteHTLC { per_commitment_point: *revocation_point, key: htlc_privkey, preimage, amount: htlc.amount_msat / 1000, locktime: htlc.cltv_expiry };
                                                                claimable_outpoints.push(ClaimRequest { absolute_timelock: htlc.cltv_expiry, aggregable, outpoint: BitcoinOutPoint { txid: commitment_txid, vout: transaction_output_index }, witness_data });
                                                        }
                                                }
index cb06fcbae5674d6239b959b7d8550bd0b6a4bb38..aee25ef6d27c6cf7a8f0647c6e86b4748ca7595a 100644 (file)
@@ -673,20 +673,34 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                                                        log_trace!(self, "Going to broadcast Penalty Transaction {} claiming revoked {} output {} from {} with new feerate {}...", bumped_tx.txid(), if *input_descriptor == InputDescriptors::RevokedOutput { "to_local" } else if *input_descriptor == InputDescriptors::RevokedOfferedHTLC { "offered" } else if *input_descriptor == InputDescriptors::RevokedReceivedHTLC { "received" } else { "" }, outp.vout, outp.txid, new_feerate);
                                                }
                                        },
-                                       &InputMaterial::RemoteHTLC { ref witness_script, ref key, ref preimage, ref amount, ref locktime } => {
-                                               if !preimage.is_some() { bumped_tx.lock_time = *locktime }; // Right now we don't aggregate time-locked transaction, if we do we should set lock_time before to avoid breaking hash computation
-                                               let sighash_parts = bip143::SighashComponents::new(&bumped_tx);
-                                               let sighash = hash_to_message!(&sighash_parts.sighash_all(&bumped_tx.input[i], &witness_script, *amount)[..]);
-                                               let sig = self.secp_ctx.sign(&sighash, &key);
-                                               bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
-                                               bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
-                                               if let &Some(preimage) = preimage {
-                                                       bumped_tx.input[i].witness.push(preimage.clone().0.to_vec());
-                                               } else {
-                                                       bumped_tx.input[i].witness.push(vec![]);
+                                       &InputMaterial::RemoteHTLC { ref per_commitment_point, ref key, ref preimage, ref amount, ref locktime } => {
+                                               if let Ok(chan_keys) = TxCreationKeys::new(&self.secp_ctx, &per_commitment_point, &self.remote_tx_cache.remote_delayed_payment_base_key, &self.remote_tx_cache.remote_htlc_base_key, &self.key_storage.pubkeys().revocation_basepoint, &self.key_storage.pubkeys().htlc_basepoint) {
+                                                       let mut this_htlc = None;
+                                                       if let Some(htlcs) = self.remote_tx_cache.per_htlc.get(&outp.txid) {
+                                                               for htlc in htlcs {
+                                                                       if htlc.transaction_output_index.unwrap() == outp.vout {
+                                                                               this_htlc = Some(htlc);
+                                                                       }
+                                                               }
+                                                       }
+                                                       if this_htlc.is_none() { return None; }
+                                                       let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&this_htlc.unwrap(), &chan_keys.a_htlc_key, &chan_keys.b_htlc_key, &chan_keys.revocation_key);
+
+                                                       if !preimage.is_some() { bumped_tx.lock_time = *locktime }; // Right now we don't aggregate time-locked transaction, if we do we should set lock_time before to avoid breaking hash computation
+                                                       let sighash_parts = bip143::SighashComponents::new(&bumped_tx);
+                                                       let sighash = hash_to_message!(&sighash_parts.sighash_all(&bumped_tx.input[i], &witness_script, *amount)[..]);
+                                                       let sig = self.secp_ctx.sign(&sighash, &key);
+                                                       bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
+                                                       bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
+                                                       if let &Some(preimage) = preimage {
+                                                               bumped_tx.input[i].witness.push(preimage.clone().0.to_vec());
+                                                       } else {
+                                                               // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
+                                                               bumped_tx.input[i].witness.push(vec![]);
+                                                       }
+                                                       bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
+                                                       log_trace!(self, "Going to broadcast Claim Transaction {} claiming remote {} htlc output {} from {} with new feerate {}...", bumped_tx.txid(), if preimage.is_some() { "offered" } else { "received" }, outp.vout, outp.txid, new_feerate);
                                                }
-                                               bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
-                                               log_trace!(self, "Going to broadcast Claim Transaction {} claiming remote {} htlc output {} from {} with new feerate {}...", bumped_tx.txid(), if preimage.is_some() { "offered" } else { "received" }, outp.vout, outp.txid, new_feerate);
                                        },
                                        _ => unreachable!()
                                }