Unable to parse specifications involving nested messages

[isaahzorgh]

There is a bug in PyRFLX parsing specifications with Protocol::ascpect_of_protocol.
This bug happens while validating the TCP specification in https://github.com/Componolit/RecordFlux-specifications/tree/issue_27 but with the commented lines with the length restrictions uncommented.

[treiher]

Could you please provide a permanent link to the affected line of the specification file? What is the concrete error message?

[isaahzorgh]

The line in the specification would be: https://github.com/Componolit/RecordFlux-specifications/blob/db9b5317da6f5d7934ae5cb84314154d50760ab7/tcp.rflx#L57
with the following line in the same style showing the same bug and error message.

This error message would be:

Traceback (most recent call last):
  File "validate_spec.py", line 414, in <module>
    sys.exit(cli(sys.argv))
  File "validate_spec.py", line 120, in cli
    args.target_coverage,
  File "validate_spec.py", line 161, in validate
    validation_result = _validate_message(path, is_valid_directory, message_value)
  File "validate_spec.py", line 195, in _validate_message
    parser_result.parse(original_message)
  File "/PATH/TO/RecordFlux-specifications/venv/lib/python3.7/site-packages/rflx/pyrflx/typevalue.py", line 793, in parse
    ) = set_field_with_size(current_field_name, current_field_size)
  File "/PATH/TO/RecordFlux-specifications/venv/lib/python3.7/site-packages/rflx/pyrflx/typevalue.py", line 772, in set_field_with_size
    value[current_pos_in_bitstring : current_pos_in_bitstring + field_size],
  File "/PATH/TO/RecordFlux-specifications/venv/lib/python3.7/site-packages/rflx/pyrflx/typevalue.py", line 872, in set
    field.typeval.parse(value)
  File "/PATH/TO/RecordFlux-specifications/venv/lib/python3.7/site-packages/rflx/pyrflx/typevalue.py", line 453, in parse
    nested_message.parse(value, check)
  File "/PATH/TO/RecordFlux-specifications/venv/lib/python3.7/site-packages/rflx/pyrflx/typevalue.py", line 778, in parse
    current_field = self._fields[current_field_name]
KeyError: ''```

[treiher]

The expression in the referenced specification is invalid, as 'Size is missing on TCP::Shift_Cnt. So that is actually a bug in the message validation (#686).