andrewbonney / mdns-debugger Goto Github PK

Just played with your package a bit and noticed that most of my traffic doesn't show up in the printed summary (and it displays way more received packets than actually displayed).

Problem lies in the dpkt package which doesn't support parsing the ResourceRecord NSEC (47). NSEC is heavily used in mdns and is defined to be a negative response. AFAIK mDNSResponder includes a NSEC record in every response it sends, or at least pretty much all of my Apple Bonjour certified accessories.
The problem is that dpkt doesn't just ignore that one record it can't parse, but completely refuses to continue to parse the packet and throws a UnpackError: RR type 47 is not supported.

The error bubbles up into parse_packet where it is silently ignored

A new python3 has been released and it caused a breaking change in 3.10

Traceback (most recent call last):
  File "/mnt/disk0/Users/user/Nextcloud/PC-SYNC/Projects/_source_codes/github/mdns-debugger/mdns-debugger.py", line 464, in <module>
    (header, packet) = cap.next()
SystemError: PY_SSIZE_T_CLEAN macro must be defined for '#' formats