SyntaxError when parsing header set by Microsoft

[lukn]

AuthenticationResultsHeader.parse('Authentication-Results: spf=pass (sender IP is 0.0.0.0) smtp.mailfrom=example.com; dkim=pass (signature was verified) header.d=example.com;dmarc=pass action=none header.from=example.com;compauth=pass reason=100')

results in

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/xxx/venv/fuglu/lib/python3.9/site-packages/authres/__init__.py", line 206, in parse
    return authres.core.AuthenticationResultsHeader.parse(core_features(), string)
  File "/home/xxx/venv/fuglu/lib/python3.9/site-packages/authres/core.py", line 442, in parse
    return self.parse_value(feature_context, string)
  File "/home/xxx/venv/fuglu/lib/python3.9/site-packages/authres/core.py", line 454, in parse_value
    header._parse()
  File "/home/xxx/venv/fuglu/lib/python3.9/site-packages/authres/core.py", line 523, in _parse
    raise SyntaxError('Expected "none" or at least one resinfo', self._parse_text)
authres.core.SyntaxError: Syntax error: Expected "none" or at least one resinfo at: smtp.mailfrom=example.com; dkim=pass (si...

Obviously the world market leader is unable to create a header according to spec (we're all surprised, yes?). I guess once again it's easier if we bend and adjust to embrace, extend, extinguish rather than wasting our energy trying to get them to do things right.

[Scott Kitterman (kitterman)]

The error message isn't very helpful, but what's missing is the authserv-id. My recommendation would be to catch the error and discard the header field since it's not useful as is. Have a look at RFC 8601, Section 2.5 for an explanation of why it's required.

[lukn (lukn)]

Thank you for the quick response. In the end we needed to apply a bunch of tricks and patch the broken header to create a valid ARC signature that was accepted by Microsoft again:
https://gitlab.com/fumail/fuglu/-/blob/2b3412caf0c811d0d33186487cd8761b9830901c/fuglu/src/fuglu/plugins/domainauth.py#L302

-> problem solved!