urllib: no_proxy variable values with leading dot not properly handled

[tloetzer]

BPO	29142
Nosy	@berkerpeksag, @vadmium, @zvyn, @zhangyangyu
PRs	curses: use tempfile.TemporaryFile for get/putwin #53 [Do Not Merge] Convert Misc/NEWS so that it is managed by towncrier #552
Files	ignore_dots-v1.patch ignore_dots-v2.patch: removed unitended refactoring ignore_dots-v3.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/zhangyangyu'
closed_at = <Date 2017-01-09.05:37:34.866>
created_at = <Date 2017-01-03.14:09:49.099>
labels = ['3.7', 'type-bug', 'library']
title = 'urllib: no_proxy variable values with leading dot not properly handled'
updated_at = <Date 2017-03-31.16:36:22.740>
user = 'https://bugs.python.org/tloetzer'

bugs.python.org fields:

activity = <Date 2017-03-31.16:36:22.740>
actor = 'dstufft'
assignee = 'xiang.zhang'
closed = True
closed_date = <Date 2017-01-09.05:37:34.866>
closer = 'xiang.zhang'
components = ['Library (Lib)']
creation = <Date 2017-01-03.14:09:49.099>
creator = 'tloetzer'
dependencies = []
files = ['46154', '46168', '46207']
hgrepos = []
issue_num = 29142
keywords = ['patch']
message_count = 10.0
messages = ['284565', '284702', '284705', '284714', '284717', '284811', '284967', '285016', '285019', '285023']
nosy_count = 6.0
nosy_names = ['python-dev', 'berker.peksag', 'martin.panter', 'zvyn', 'xiang.zhang', 'tloetzer']
pr_nums = ['53', '552']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29142'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6', 'Python 3.7']

[tloetzer]

Hi,

the fix for bpo-26864 changed the behavior of urllib for no_proxy values with a leading dot to no longer match anything. This seems to be caused by always adding an additional dot between the hostname being checked and the entry.

Example:
no_proxy = '.company.internal'

I would expect 'somehost.company.internal' to be accessed without proxy, but this is not actually the case. Changing no_proxy to company.internal changes this and the host is accessed without proxy.

Python 2.7.11 and curl both handle this case fine and the proxy is not used.

Regards,
Thomas

[zvyn]

I added a line stripping dots from name, I think it makes sense to strip at the end as well (example.com is the same domain as example.com.).

[berkerpeksag]

Note: We don't officially use pull requests yet. Current way of contributing to Python is documented at https://docs.python.org/devguide/patch.html

[zvyn]

Too bad, I was all exited when I saw that I can paste a PR link here :)

I downloaded the patch from the commit using github, I hope that works?

[berkerpeksag]

Yes, thanks!

[zhangyangyu]

I think it makes sense to strip at the end as well (example.com is the same domain as example.com.).

Are your sure the host checked against the list is FQDN? With and without the trailing dot are different.

[zvyn]

Thanks for the feedback!

I changed the patch to use lstrip so that the FQDN "example.com." would match the NOPROXY entry "example.com.". I don't think we get FQDNs, but that's just my guess.

I think ideally "example.com" would also match "example.com." but that's a different issue.

[zhangyangyu]

LGTM.