Detect OpenID discovery errors and return proper error message

[François Marier]

When OpenID fails to parse the HTML page it was given, we don't get any useful debugging information:

Traceback (most recent call last):

  File "/usr/lib/pymodules/python2.6/django/core/handlers/base.py", line 100, in get_response
    response = callback(request, *callback_args, **callback_kwargs)

  File "/usr/lib/pymodules/python2.6/django/contrib/auth/decorators.py", line 25, in _wrapped_view
    return view_func(request, *args, **kwargs)

  File "/usr/share/libravatar/libravatar/account/views.py", line 276, in redirect_openid
    auth_request = openid_consumer.begin(user_url)

  File "/usr/lib/pymodules/python2.6/openid/consumer/consumer.py", line 345, in begin
    service = disco.getNextService(self._discover)

  File "/usr/lib/pymodules/python2.6/openid/yadis/manager.py", line 105, in getNextService
    yadis_url, services = discover(self.url)

  File "/usr/lib/pymodules/python2.6/openid/consumer/discover.py", line 470, in discover
    return discoverURI(identifier)

  File "/usr/lib/pymodules/python2.6/openid/consumer/discover.py", line 462, in discoverURI
    claimed_id, openid_services = discoverYadis(uri)

  File "/usr/lib/pymodules/python2.6/openid/consumer/discover.py", line 389, in discoverYadis
    response = yadisDiscover(uri)

  File "/usr/lib/pymodules/python2.6/openid/yadis/discover.py", line 83, in discover
    result.xrds_uri = whereIsYadis(resp)

  File "/usr/lib/pymodules/python2.6/openid/yadis/discover.py", line 130, in whereIsYadis
    yadis_loc = findHTMLMeta(StringIO(resp.body))

  File "/usr/lib/pymodules/python2.6/openid/yadis/parsehtml.py", line 182, in findHTMLMeta
    parser.feed(chunk)

  File "/usr/lib/pymodules/python2.6/openid/yadis/parsehtml.py", line 156, in feed
    return HTMLParser.feed(self, chars)

  File "/usr/lib/python2.6/HTMLParser.py", line 108, in feed
    self.goahead(0)

  File "/usr/lib/python2.6/HTMLParser.py", line 148, in goahead
    k = self.parse_starttag(i)

  File "/usr/lib/python2.6/HTMLParser.py", line 252, in parse_starttag
    attrvalue = self.unescape(attrvalue)

  File "/usr/lib/python2.6/HTMLParser.py", line 390, in unescape
    return re.sub(r"&(#?[xX]?(?:[0-9a-fA-F]+|\w{1,8}));", replaceEntities, s)

  File "/usr/lib/python2.6/re.py", line 151, in sub
    return _compile(pattern, 0).sub(repl, string, count)

UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 15: ordinal not in range(128)

We need to catch that error (UnicodeDecodeError?) so that we can display a better error to the user than a 500.

Also, we need to find a way to add these to the error message:

- user ID
- Open ID URL