Test suite may crash with "Layer 'quic' does not exist in packet"

[koujaz]

Since recent addition of connectionmigration tests we started to observe a packet without quic layer in certain client/server combinations.
It will kill whole execution with the following exception:

...
Server: akamai-quic. Client: lsquic. Running test case: connectionmigration
    sys.exit(main())
  File "/quic-interop-runner/./run.py", line 179, in main
    ).run()
  File "/quic-interop-runner/interop.py", line 545, in run
    status = self._run_testcase(server, client, testcase)
  File "/quic-interop-runner/interop.py", line 365, in _run_testcase
    return self._run_test(server, client, None, test)[0]
  File "/quic-interop-runner/interop.py", line 465, in _run_test
    status = testcase.check()
  File "/quic-interop-runner/testcases.py", line 1469, in check
    super().check()
  File "/quic-interop-runner/testcases.py", line 1363, in check
    tr_server = self._server_trace()._get_packets(
  File "/quic-interop-runner/trace.py", line 123, in _get_packets
    if hasattr(p["quic"], "decryption_failed"):
  File "/usr/local/lib/python3.10/dist-packages/pyshark/packet/packet.py", line 52, in __getitem__
    raise KeyError('Layer does not exist in packet')
KeyError: 'Layer does not exist in packet'

Looking at the dump (see screenshot):

• client sends CC and closes the listening port immediately
• server responds ACK (to the CC)
• this ACK causes the return of "ICMPv6 Port unreachable" packet
• this returning packet contains original QUIC UDP packet as payload and this confuses packet parsing (packet is captured by filter but there is no QUIC layer - which is IMHO correct as this doesn't belong to QUIC communication)

Notes:

• using quic-interop-runner version from this commit: f57bcf2
• tshark built from this commit: v4.5.0rc0-1586-g0cea822e7889
• pyshark 0.6 (from pip)

[marten-seemann]

Probably need to add a check if it's actually a QUIC packet. Want to submit a patch?

[koujaz]

Yes, I'll submit a patch to skip packets w/o 'quic' layer.