+
+ /// Add local signature for a htlc transaction, do nothing if a cached signed transaction is
+ /// already present
+ pub fn add_htlc_sig<T: secp256k1::Signing>(&mut self, htlc_base_key: &SecretKey, htlc_index: u32, preimage: Option<PaymentPreimage>, local_csv: u16, secp_ctx: &Secp256k1<T>) {
+ let txid = self.txid();
+ for this_htlc in self.per_htlc.iter_mut() {
+ if this_htlc.0.transaction_output_index == Some(htlc_index) {
+ if this_htlc.2.is_some() { return; } // we already have a cached htlc transaction at provided index
+ let mut htlc_tx = build_htlc_transaction(&txid, self.feerate_per_kw, local_csv, &this_htlc.0, &self.local_keys.a_delayed_payment_key, &self.local_keys.revocation_key);
+ if !this_htlc.0.offered && preimage.is_none() { return; } // if we don't have preimage for HTLC-Success, don't try to generate
+ let htlc_secret = if !this_htlc.0.offered { preimage } else { None }; // if we have a preimage for HTLC-Timeout, don't use it that's likely a duplicate HTLC hash
+ if this_htlc.1.is_none() { return; } // we don't have any remote signature for this htlc
+ if htlc_tx.input.len() != 1 { return; }
+ if htlc_tx.input[0].witness.len() != 0 { return; }
+
+ let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc.0, &self.local_keys.a_htlc_key, &self.local_keys.b_htlc_key, &self.local_keys.revocation_key);
+
+ if let Ok(our_htlc_key) = derive_private_key(secp_ctx, &self.local_keys.per_commitment_point, htlc_base_key) {
+ let sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, this_htlc.0.amount_msat / 1000)[..]);
+ let our_sig = secp_ctx.sign(&sighash, &our_htlc_key);
+
+ htlc_tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
+
+ htlc_tx.input[0].witness.push(this_htlc.1.unwrap().serialize_der().to_vec());
+ htlc_tx.input[0].witness.push(our_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 this_htlc.0.offered {
+ htlc_tx.input[0].witness.push(Vec::new());
+ assert!(htlc_secret.is_none());
+ } else {
+ htlc_tx.input[0].witness.push(htlc_secret.unwrap().0.to_vec());
+ }
+
+ htlc_tx.input[0].witness.push(htlc_redeemscript.as_bytes().to_vec());
+
+ this_htlc.2 = Some(htlc_tx);
+ } else { return; }
+ }
+ }
+ }
+ /// Expose raw htlc transaction, guarante witness is complete if non-empty
+ pub fn htlc_with_valid_witness(&self, htlc_index: u32) -> &Option<Transaction> {
+ for this_htlc in self.per_htlc.iter() {
+ if this_htlc.0.transaction_output_index.unwrap() == htlc_index {
+ return &this_htlc.2;
+ }
+ }
+ &None
+ }