agent: Drop valid but unmatched STUN packets
Rather than passing them through to the application. Invalid STUN packets are still passed through, but it causes unnecessary noise and corruption for higher-level applications to receive STUN packets they weren’t expecting. This is permitted by RFC 5389, §7.3.0: If any errors are detected, the message is silently discarded. In the case when STUN is being multiplexed with another protocol, an error may indicate that this is not really a STUN message; in this case, the agent should try to parse the message as a different protocol. where I interpret ‘error’ to mean ‘validation error’ rather than (e.g.) ‘unrecognised attribute’ or ‘unmatched response’ where the STUN packet is otherwise perfectly formed.