Let ChannelSigner set commit tx htlc output script pubkey

Author: tankyleo

lightning/src/ln/chan_utils.rs

@@ -1557,9 +1557,8 @@ impl CommitmentTransaction {
 
 		let mut htlcs = Vec::with_capacity(htlcs_with_aux.len());
 		for (htlc, _) in htlcs_with_aux {
-			let script = get_htlc_redeemscript(&htlc, &channel_parameters.channel_type_features(), &keys);
 			let txout = TxOut {
-				script_pubkey: script.to_p2wsh(),
+				script_pubkey: signer.get_htlc_spk(htlc, is_holder_tx, &keys.per_commitment_point, secp_ctx),
 				value: htlc.to_bitcoin_amount(),
 			};
 			txouts.push((txout, Some(htlc)));

lightning/src/sign/mod.rs

@@ -952,6 +952,12 @@ pub trait ChannelSigner {
 	/// Gets the weight of the witness of the input that spends the htlc output of a
 	/// holder commitment transaction
 	fn get_holder_htlc_transaction_witness_weight(&self, offered: bool) -> u64;
+
+	/// Gets the script pubkey of a htlc output in a commitment transaction
+	fn get_htlc_spk(
+		&self, htlc: &HTLCOutputInCommitment, is_holder_tx: bool, per_commitment_point: &PublicKey,
+		secp_ctx: &Secp256k1<secp256k1::All>,
+	) -> ScriptBuf;
 }
 
 /// Specifies the recipient of an invoice.
@@ -1812,6 +1818,25 @@ impl ChannelSigner for InMemorySigner {
 			chan_utils::HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT
 		}
 	}
+
+	fn get_htlc_spk(
+		&self, htlc: &HTLCOutputInCommitment, is_holder_tx: bool, per_commitment_point: &PublicKey,
+		secp_ctx: &Secp256k1<secp256k1::All>,
+	) -> ScriptBuf {
+		let params = if is_holder_tx {
+			self.channel_parameters.as_ref().unwrap().as_holder_broadcastable()
+		} else {
+			self.channel_parameters.as_ref().unwrap().as_counterparty_broadcastable()
+		};
+		let keys = TxCreationKeys::from_channel_static_keys(
+			per_commitment_point,
+			params.broadcaster_pubkeys(),
+			params.countersignatory_pubkeys(),
+			secp_ctx,
+		);
+		let script = chan_utils::get_htlc_redeemscript(htlc, params.channel_type_features(), &keys);
+		script.to_p2wsh()
+	}
 }
 
 const MISSING_PARAMS_ERR: &'static str =

lightning/src/util/test_channel_signer.rs

@@ -353,6 +353,10 @@ impl ChannelSigner for TestChannelSigner {
 	fn get_holder_htlc_transaction_witness_weight(&self, offered: bool) -> u64 {
 		self.inner.get_holder_htlc_transaction_witness_weight(offered)
 	}
+
+	fn get_htlc_spk(&self, htlc: &HTLCOutputInCommitment, holder_tx: bool, per_commitment_point: &PublicKey, secp_ctx: &Secp256k1<secp256k1::All>) -> ScriptBuf {
+		self.inner.get_htlc_spk(htlc, holder_tx, per_commitment_point, secp_ctx)
+	}
 }
 
 impl EcdsaChannelSigner for TestChannelSigner {