f Add references to BIP 147 + 146

Author: TheBlueMatt

lightning/src/ln/chan_utils.rs

@@ -652,14 +652,16 @@ impl LocalCommitmentTransaction {
 
 		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);
 
-		htlc_tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
+		// First push the multisig dummy, note that due to BIP147 (NULLDUMMY) it must be a zero-length element.
+		htlc_tx.input[0].witness.push(Vec::new());
 
 		htlc_tx.input[0].witness.push(this_htlc.1.unwrap().serialize_der().to_vec());
 		htlc_tx.input[0].witness.push(signature.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 {
+			// Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
 			htlc_tx.input[0].witness.push(Vec::new());
 		} else {
 			htlc_tx.input[0].witness.push(preimage.unwrap().0.to_vec());