Fix to_remote output redeemscript when anchors enabled

Author: ksedgwic

lightning/src/ln/chan_utils.rs

@@ -608,6 +608,17 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
 	}
 }
 
+/// Gets the witnessScript for the to_remote output when anchors are enabled.
+#[inline]
+pub(crate) fn get_to_countersignatory_with_anchors_redeemscript(payment_point: &PublicKey) -> Script {
+	Builder::new()
+		.push_slice(&payment_point.serialize()[..])
+		.push_opcode(opcodes::all::OP_CHECKSIGVERIFY)
+		.push_int(1)
+		.push_opcode(opcodes::all::OP_CSV)
+		.into_script()
+}
+
 /// Gets the witnessScript for an anchor output from the funding public key.
 /// The witness in the spending input must be:
 /// <BIP 143 funding_signature>
@@ -1130,7 +1141,11 @@ impl CommitmentTransaction {
 		let mut txouts: Vec<(TxOut, Option<&mut HTLCOutputInCommitment>)> = Vec::new();
 
 		if to_countersignatory_value_sat > 0 {
-			let script = script_for_p2wpkh(&countersignatory_pubkeys.payment_point);
+			let script = if opt_anchors {
+			    get_to_countersignatory_with_anchors_redeemscript(&countersignatory_pubkeys.payment_point).to_v0_p2wsh()
+			} else {
+			    script_for_p2wpkh(&countersignatory_pubkeys.payment_point)
+			};
 			txouts.push((
 				TxOut {
 					script_pubkey: script.clone(),