add config variable to test update_fail_malformed_htlc

electrum/lnpeer.py

@@ -1495,6 +1495,7 @@ class Peer(Logger):
                     onion_packet_bytes = bytes.fromhex(onion_packet_hex)
                     onion_packet = None
                     try:
+                        if self.network.config.get('test_fail_malformed_htlc'): raise InvalidOnionPubkey()
                         onion_packet = OnionPacket.from_bytes(onion_packet_bytes)
                         processed_onion = process_onion_packet(onion_packet, associated_data=payment_hash, our_onion_private_key=self.privkey)
                     except UnsupportedOnionPacketVersion:

electrum/tests/regtest/regtest.sh

@@ -104,6 +104,7 @@ fi
 
 if [[ $1 == "configure_test_forwarding" ]]; then
     $bob setconfig --offline lightning_forward_payments true
+    # $carol setconfig --offline test_fail_malformed_htlc true # uncomment to test update_fail_malformed_htlc
 fi
 
 if [[ $1 == "open" ]]; then