Implement claiming of revoked HTLC transactions by ChannelMonitor
authorAntoine Riard <ariard@student.42.fr>
Tue, 11 Sep 2018 01:40:53 +0000 (01:40 +0000)
committerAntoine Riard <ariard@student.42.fr>
Wed, 12 Sep 2018 23:50:58 +0000 (23:50 +0000)
Refactor check_spend_remote_transaction in part to check_spend_remote_htlc to
avoid lock mess in block_connected. We need
remote_commitment_txn_on_chain to match remote HTLC tx

src/ln/channelmonitor.rs

index 81efedcbffd1408e0f6b8268b8e7b4eed9a5279a..6de0a63609ac6a4c8333796ad6da639f0c0760fe 100644 (file)
@@ -924,8 +924,7 @@ impl ChannelMonitor {
        /// Attempts to claim a remote commitment transaction's outputs using the revocation key and
        /// data in remote_claimable_outpoints. Will directly claim any HTLC outputs which expire at a
        /// height > height + CLTV_SHARED_CLAIM_BUFFER. In any case, will install monitoring for
-       /// HTLC-Success/HTLC-Timeout transactions, and claim them using the revocation key (if
-       /// applicable) as well.
+       /// HTLC-Success/HTLC-Timeout transactions.
        fn check_spend_remote_transaction(&self, tx: &Transaction, height: u32) -> (Vec<Transaction>, (Sha256dHash, Vec<TxOut>)) {
                // Most secp and related errors trying to create keys means we have no hope of constructing
                // a spend transaction...so we return no transactions to broadcast
@@ -1205,13 +1204,97 @@ impl ChannelMonitor {
                                        txn_to_broadcast.push(spend_tx);
                                }
                        }
-               } else {
-                       //TODO: For each input check if its in our remote_commitment_txn_on_chain map!
                }
 
                (txn_to_broadcast, (commitment_txid, watch_outputs))
        }
 
+       /// Attempst to claim a remote HTLC-Success/HTLC-Timeout s outputs using the revocation key
+       fn check_spend_remote_htlc(&self, tx: &Transaction, commitment_number: u64) -> Vec<Transaction> {
+               let mut txn_to_broadcast = Vec::new();
+
+               let htlc_txid = tx.txid(); //TODO: This is gonna be a performance bottleneck for watchtowers!
+
+               macro_rules! ignore_error {
+                       ( $thing : expr ) => {
+                               match $thing {
+                                       Ok(a) => a,
+                                       Err(_) => return txn_to_broadcast
+                               }
+                       };
+               }
+
+               let secret = self.get_secret(commitment_number).unwrap();
+               let per_commitment_key = ignore_error!(SecretKey::from_slice(&self.secp_ctx, &secret));
+               let revocation_pubkey = match self.key_storage {
+                       KeyStorage::PrivMode { ref revocation_base_key, .. } => {
+                               let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key);
+                               ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &PublicKey::from_secret_key(&self.secp_ctx, &revocation_base_key)))
+                       },
+                       KeyStorage::SigsMode { ref revocation_base_key, .. } => {
+                               let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key);
+                               ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &revocation_base_key))
+                       },
+               };
+               let delayed_key = match self.their_delayed_payment_base_key {
+                       None => return txn_to_broadcast,
+                       Some(their_delayed_payment_base_key) => ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key), &their_delayed_payment_base_key)),
+               };
+               let redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.their_to_self_delay.unwrap(), &delayed_key);
+               let revokeable_p2wsh = redeemscript.to_v0_p2wsh();
+
+               let mut inputs = Vec::new();
+               let mut amount = 0;
+
+               if tx.output[0].script_pubkey == revokeable_p2wsh { //HTLC transactions have one txin, one txout
+                       inputs.push(TxIn {
+                               previous_output: BitcoinOutPoint {
+                                       txid: htlc_txid,
+                                       vout: 0,
+                               },
+                               script_sig: Script::new(),
+                               sequence: 0xfffffffd,
+                               witness: Vec::new(),
+                       });
+                       amount = tx.output[0].value;
+               }
+
+               if !inputs.is_empty() {
+                       let outputs = vec!(TxOut {
+                               script_pubkey: self.destination_script.clone(),
+                               value: amount, //TODO: - fee
+                       });
+
+                       let mut spend_tx = Transaction {
+                               version: 2,
+                               lock_time: 0,
+                               input: inputs,
+                               output: outputs,
+                       };
+
+
+                       let sighash_parts = bip143::SighashComponents::new(&spend_tx);
+
+                       let sig = match self.key_storage {
+                               KeyStorage::PrivMode { ref revocation_base_key, .. } => {
+                                       let sighash = ignore_error!(Message::from_slice(&sighash_parts.sighash_all(&spend_tx.input[0], &redeemscript, amount)[..]));
+                                       let revocation_key = ignore_error!(chan_utils::derive_private_revocation_key(&self.secp_ctx, &per_commitment_key, &revocation_base_key));
+                                       self.secp_ctx.sign(&sighash, &revocation_key)
+                               }
+                               KeyStorage::SigsMode { .. } => {
+                                       unimplemented!();
+                               }
+                       };
+                       spend_tx.input[0].witness.push(sig.serialize_der(&self.secp_ctx).to_vec());
+                       spend_tx.input[0].witness[0].push(SigHashType::All as u8);
+                       spend_tx.input[0].witness.push(vec!(1));
+                       spend_tx.input[0].witness.push(redeemscript.into_bytes());
+
+                       txn_to_broadcast.push(spend_tx);
+               }
+               txn_to_broadcast
+       }
+
        fn broadcast_by_local_state(&self, local_tx: &LocalSignedTx) -> Vec<Transaction> {
                let mut res = Vec::with_capacity(local_tx.htlc_outputs.len());
 
@@ -1273,19 +1356,26 @@ impl ChannelMonitor {
        fn block_connected(&self, txn_matched: &[&Transaction], height: u32, broadcaster: &BroadcasterInterface)-> Vec<(Sha256dHash, Vec<TxOut>)> {
                let mut watch_outputs = Vec::new();
                for tx in txn_matched {
+                       let mut txn: Vec<Transaction> = Vec::new();
                        for txin in tx.input.iter() {
                                if self.funding_txo.is_none() || (txin.previous_output.txid == self.funding_txo.as_ref().unwrap().0.txid && txin.previous_output.vout == self.funding_txo.as_ref().unwrap().0.index as u32) {
-                                       let (mut txn, new_outputs) = self.check_spend_remote_transaction(tx, height);
+                                       let (remote_txn, new_outputs) = self.check_spend_remote_transaction(tx, height);
+                                       txn = remote_txn;
                                        if !new_outputs.1.is_empty() {
                                                watch_outputs.push(new_outputs);
                                        }
                                        if txn.is_empty() {
                                                txn = self.check_spend_local_transaction(tx, height);
                                        }
-                                       for tx in txn.iter() {
-                                               broadcaster.broadcast_transaction(tx);
+                               } else {
+                                       let remote_commitment_txn_on_chain = self.remote_commitment_txn_on_chain.lock().unwrap();
+                                       for commitment_number in remote_commitment_txn_on_chain.get(&txin.previous_output.txid) {
+                                               txn =  self.check_spend_remote_htlc(tx, *commitment_number);
                                        }
                                }
+                               for tx in txn.iter() {
+                                       broadcaster.broadcast_transaction(tx);
+                               }
                        }
                }
                if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx {