Parse an HTTP request Authorization header with Python

Question

I need to take a header like this:

 Authorization: Digest qop="chap",
     realm="[email protected]",
     username="Foobear",
     response="6629fae49393a05397450978507c4ef1",
     cnonce="5ccc069c403ebaf9f0171e9517f40e41"

And parse it into this using Python:

{'protocol':'Digest',
  'qop':'chap',
  'realm':'[email protected]',
  'username':'Foobear',
  'response':'6629fae49393a05397450978507c4ef1',
  'cnonce':'5ccc069c403ebaf9f0171e9517f40e41'}

Is there a library to do this, or something I could look at for inspiration?

I'm doing this on Google App Engine, and I'm not sure if the Pyparsing library is available, but maybe I could include it with my app if it is the best solution.

Currently I'm creating my own MyHeaderParser object and using it with reduce() on the header string. It's working, but very fragile.

Brilliant solution by nadia below:

import re

reg = re.compile('(\w+)[=] ?"?(\w+)"?')

s = """Digest
realm="stackoverflow.com", username="kixx"
"""

print str(dict(reg.findall(s)))

Answer 1

A little regex:

import re
reg=re.compile('(\w+)[:=] ?"?(\w+)"?')

>>>dict(reg.findall(headers))

{'username': 'Foobear', 'realm': 'testrealm', 'qop': 'chap', 'cnonce': '5ccc069c403ebaf9f0171e9517f40e41', 'response': '6629fae49393a05397450978507c4ef1', 'Authorization': 'Digest'}

Answer 2

You can also use urllib2 as [CheryPy][1] does.

here is the snippet:

input= """
 Authorization: Digest qop="chap",
     realm="[email protected]",
     username="Foobear",
     response="6629fae49393a05397450978507c4ef1",
     cnonce="5ccc069c403ebaf9f0171e9517f40e41"
"""
import urllib2
field, sep, value = input.partition("Authorization: Digest ")
if value:
    items = urllib2.parse_http_list(value)
    opts = urllib2.parse_keqv_list(items)
    opts['protocol'] = 'Digest'
    print opts

it outputs:

{'username': 'Foobear', 'protocol': 'Digest', 'qop': 'chap', 'cnonce': '5ccc069c403ebaf9f0171e9517f40e41', 'realm': '[email protected]', 'response': '6629fae49393a05397450978507c4ef1'}

[1]: https://web.archive.org/web/20130118133623/http://www.google.com:80/codesearch/p?hl=en#OQvO9n2mc04/CherryPy-3.0.1/cherrypy/lib/httpauth.py&q=Authorization Digest http lang:python