urllib2 http authorization question

[Troels Therkelsen]

In article <slrnbtp86j.l9u.matt at overlook.homelinux.net>, Matthew Wilson wrote:

[snip]
>>>> lookup.mr814('username', 'password')
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
>   File "lookup.py", line 13, in mr814
>     for line in urllib2.urlopen(req):
>   File "/usr/lib/python2.3/urllib2.py", line 136, in urlopen
>     return _opener.open(url, data)
>   File "/usr/lib/python2.3/urllib2.py", line 333, in open
>     '_open', req)
>   File "/usr/lib/python2.3/urllib2.py", line 313, in _call_chain
>     result = func(*args)
>   File "/usr/lib/python2.3/urllib2.py", line 849, in http_open
>     return self.do_open(httplib.HTTP, req)
>   File "/usr/lib/python2.3/urllib2.py", line 843, in do_open
>     return self.parent.error('http', req, fp, code, msg, hdrs)
>   File "/usr/lib/python2.3/urllib2.py", line 359, in error
>     return self._call_chain(*args)
>   File "/usr/lib/python2.3/urllib2.py", line 313, in _call_chain
>     result = func(*args)
>   File "/usr/lib/python2.3/urllib2.py", line 419, in http_error_default
>     raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
> urllib2.HTTPError: HTTP Error 401: Unauthorized
>>>> lookup.mr814('admin', '54wins')
> '66.72.200.255'

To me, but maybe this is a copy-n-paste error, it looks like you aren't calling
lookup.mr814() with exactly the same args:

    >>> lookup.mr814('username', 'password')

versus

    >>> lookup.mr814('admin', '54wins')

?

> 
> This is baffling me.  Does the webserver ignore the AUTHORIZATION header
> on the first request?  Should I do something like this:
> 
>>>> try:
> ...     lookup.mr814('admin', '54wins')
> ... except urllib2.HTTPError: #I only want to catch 401 here, but how?
> ...     print "I got back the 401 error.  Trying again..."
> ...     lookup.mr814('admin', '54wins')
> ... except:
> ...     print "something else went wrong."
> 
> If that is recommended, how do I distinguish between 401 errors, vs
> other errors?

I don't know if it's recommended, but take a look at the source for the
urllib2.HTTPError class, at the definition of __str__ (which is used by the
traceback system):

    def __str__(self):
        return 'HTTP Error %s: %s' % (self.code, self.msg)

In other words, the actual HTTP error code is in self.code... you could check
for that something like this:

try:
    lookup.mr814('admin', '54wins')
except urllib2.HTTPError, err:
    if err.code != 401:
        raise

> 
> Thanks for the help.

I hope the above helps,

/Troels Therkelsen