There appears to be an odd networking issue with how urllib2 sends HTTP requests. Downloading an image from maw.liquifire.com gives an error:

$ python -c 'import urllib2 ; urllib2.urlopen("http://maw.liquifire.com/maw?set=image[2302.000.13314 a]&call=url[file:325x445]")'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/urllib2.py", line 126, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib/python2.7/urllib2.py", line 400, in open
    response = self._open(req, data)
  File "/usr/lib/python2.7/urllib2.py", line 418, in _open
    '_open', req)
  File "/usr/lib/python2.7/urllib2.py", line 378, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 1207, in http_open
    return self.do_open(httplib.HTTPConnection, req)
  File "/usr/lib/python2.7/urllib2.py", line 1180, in do_open
    r = h.getresponse(buffering=True)
  File "/usr/lib/python2.7/httplib.py", line 1030, in getresponse
    response.begin()
  File "/usr/lib/python2.7/httplib.py", line 407, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python2.7/httplib.py", line 365, in _read_status
    line = self.fp.readline()
  File "/usr/lib/python2.7/socket.py", line 447, in readline
    data = self._sock.recv(self._rbufsize)
socket.error: [Errno 104] Connection reset by peer

Downloading the same image using wget works fine:

$ wget 'http://maw.liquifire.com/maw?set=image[2302.000.13314 a]&call=url[file:325x445]'             
--2012-05-16 10:53:27--  http://maw.liquifire.com/maw?set=image[2302.000.13314%20a]&call=url[file:325x445]
Resolving maw.liquifire.com (maw.liquifire.com)... 184.169.78.6
Connecting to maw.liquifire.com (maw.liquifire.com)|184.169.78.6|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 11393 (11K) [image/jpeg]
Saving to: `maw?set=image[2302.000.13314 a]&call=url[file:325x445]'

100%[======================================>] 11,393      --.-K/s   in 0.003s  

2012-05-16 10:53:27 (3.49 MB/s) - `maw?set=image[2302.000.13314 a]&call=url[file:325x445]' saved [11393/11393]

http://maw.liquifire.com/maw?set=image[2302.000.13314%20a]&call=url[file:325x445] works properly. Notice the %20 instead of ' '

Here is a patch that uses the same quoting logic in urllib.request.Request.__init__ as is used by urllib.request.URLopener.open()

New changeset 01c8d800efd2 by Senthil Kumaran in branch '3.2':
Fix issue14826 - make urllib.request.Request quoted url consistent with URLOpener open method.
http://hg.python.org/cpython/rev/01c8d800efd2

New changeset e6bb919b2623 by Senthil Kumaran in branch 'default':
Fix issue14826 - make urllib.request.Request quoted url consistent with URLOpener open method.
http://hg.python.org/cpython/rev/e6bb919b2623

New changeset d931a3b64fd6 by Senthil Kumaran in branch '2.7':
Fix issue14826 - make urllib.request.Request quoted url consistent with URLOpener open method.
http://hg.python.org/cpython/rev/d931a3b64fd6

Thanks for the patch, Stephen.

It looks like this broke the build bots:
http://buildbot.python.org/all/builders/AMD64%20Ubuntu%20LTS%202.7/builds/66/steps/test/logs/stdio

Here's a followup patch that fixes the trunk build for me.

This will unbreak the builds as well as fixing this bug, but it should be investigated why URLopener calls to_bytes() and Request does not. Ideally this interface should be consistent.

It seems to me that toBytes in urllib was introduce to restrict the
allowance of urls which were sent as unicode strings. We wanted urls
to be ascii strings in Python2.

http://mail.python.org/pipermail/python-bugs-list/2000-November/002779.html

And quoting to toBytes / to_bytes is actually the problem here, as
cookielib test cases is sending a unicode character which ascii
encoding fails to operate on. I am thinking that we should arrive at a
solution which brings consistency and fixes any previous mistakes.  In
3.3, I think, rework of to_bytes may also be a good solution, in 2.7
and 3.2, I think stephen's attached patch is in good lines.
Practically, the quote is more important than the failure at toBytes
by sending an unicode url.

I’m not sure urllib should accept invalid (non-escaped) URLs; a higher-level application can do so, but for the low-level stdlib module it is more debatable.

Yeah, I am thinking so as well in that case, the test_cookielib.py
test case may need a change.

New changeset ee1828dc3bf6 by Senthil Kumaran in branch '3.2':
issue 14826 - Address the buildbot failure ( explanation msg164973)
http://hg.python.org/cpython/rev/ee1828dc3bf6

New changeset dc30111a5d7e by Senthil Kumaran in branch 'default':
issue 14826 - Address the buildbot failure quote of url is the required change ( explanation msg164973)
http://hg.python.org/cpython/rev/dc30111a5d7e

New changeset 224b27a8d9be by Senthil Kumaran in branch '2.7':
revert the changes done in d931a3b64fd6  - buildbot failure.
http://hg.python.org/cpython/rev/224b27a8d9be

The last change should settle the buildbots, But I would like to come
back to this issue again tomorrow with focus - 3.3    to see if we can
deal with removing to_bytes and then in 2.7 to see if something can
done to test_cookielib.py test case.

Senthil, do you read python-dev? I think this change was prematurate from the start (nevermind the fact that you didn't run the test suite before committing).

For example, if you have an URL with a non-ASCII domain name such as "http://وزارة-الأتصالات.مصر/", the domain name should IDNA-encoded, not %-encoded like the rest.

Furthermore, some people are certainly already quoting their URLs to workaround this issue, so "fixing" it will break their code by double-escaping the URLs. You've got to be more careful.

The docs [1] state that `url should be a string containing a valid URL.` An URL with a space ' ' is not a valid URL as the space must be quoted as %20. The brackets may also cause problems as they are not valid xs:anyURI chars.

I vote for reverting the chances as they break the API. You could improve the docs and emphasize that URLs must be quoted correctly as the module doesn't implement browser magic.

[1] http://docs.python.org/py3k/library/urllib.request.html#urllib.request.Request

On Sun, Jul 8, 2012 at 2:30 AM, Antoine Pitrou <report@bugs.python.org> wrote:
>
> Senthil, do you read python-dev? I think this change was prematurate from the start (nevermind the fact that you didn't run the test suite before committing).

I  thought that the other legacy URLOpen was quoting it correct and
then I wanted to see it can be made consistent.
It did get me thinking that why it was different for so long. I
realize that committing soon was a mistake.

> For example, if you have an URL with a non-ASCII domain name such as "http://وزارة-الأتصالات.مصر/", the domain name should IDNA-encoded, not %-encoded like the rest.

Agreed and understood.

> Furthermore, some people are certainly already quoting their URLs to workaround this issue, so "fixing" it will break their code by double-escaping the URLs. You've got to be more careful.

Oh. yes, the change may break an already quoted URL. I think, I shall
revert this back.

On Sun, Jul 8, 2012 at 9:42 AM, Christian Heimes <report@bugs.python.org> wrote:

> I vote for reverting the chances as they break the API. You could improve the docs and emphasize that URLs must be quoted correctly as the module doesn't implement browser magic.

Okay. But I do realize that in 3.3, we may have a FancyURLOpener /
URLOpener 's open method, which is not directly called by the apis,
but they seem to have quote behavior. I guess, I approached this
change as to making them consistent, but realize it is mistake, for
the reasons that you state and Antoine state.

New changeset ebd37273e0fe by Senthil Kumaran in branch '3.2':
revert the changes done for issue14826 - quoting witin Request is not desirable.
http://hg.python.org/cpython/rev/ebd37273e0fe

New changeset a4bdb637d818 by Senthil Kumaran in branch 'default':
revert the changes done for issue14826 - quoting witin Request is not desirable.
http://hg.python.org/cpython/rev/a4bdb637d818

FWIW urlopen() already handles space characters in the Location target of redirects; see HTTPRedirectHandler.redirect_request(). So I think it is reasonable to handle space characters in user-supplied URLs also, if it is done properly.

I think this should be treated as a feature, not a bug, since as Christian said, the documentation currently does not support this case.

urllib.request.URLopener() and FancyURLopener() automatically quote() URLs for the user.  Those APIs are marked deprecated since 3.3 but have no timeline for removal.

urllib.request.urlopen() does not use those, so URLs passed in are not auto-quoted.

i'll clarify the docs for URLopener.

New changeset 2fb2bc81c3f40d73945c6102569495140e1182c7 by Gregory P. Smith in branch 'master':
bpo-14826: document that URLopener quotes fullurl. (GH-12758)
https://github.com/python/cpython/commit/2fb2bc81c3f40d73945c6102569495140e1182c7

New changeset 9d2ccf173e2e8ff069153f603d2e5b1ea757e734 by Miss Islington (bot) in branch '3.7':
bpo-14826: document that URLopener quotes fullurl. (GH-12758)
https://github.com/python/cpython/commit/9d2ccf173e2e8ff069153f603d2e5b1ea757e734