New submission from karl:
For HTTP header field names parsing, see
http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-22#section-3.2.4
No whitespace is allowed between the header field-name and colon. In
the past, differences in the handling of such whitespace have led to
security vulnerabilities in request routing and response handling. A
server MUST reject any received request message that contains
whitespace between a header field-name and colon with a response code
of 400 (Bad Request). A proxy MUST remove any such whitespace from a
response message before forwarding the message downstream.
In python3.3 currently
>>> import urllib.request
>>> req = urllib.request.Request('http://www.example.com/')
>>> req.add_header('FoO ', 'Yeah')
>>> req.header_items()
[('Foo ', 'Yeah'), ('User-agent', 'Python-urllib/3.3'), ('Host',
'www.example.com')]
The space has not been removed. So we should fix that at least. This is a bug.
I'm not familiar with the specific security issues mentioned in the spec.
Note that many things can be done too: :/
>>> req.add_header('FoO \n blah', 'Yeah')
>>> req.add_header('Foo:Bar\nFoo2', 'Yeah')
>>> req.header_items()
[('Foo:bar\nfoo2', 'Yeah'), ('Foo \n blah', 'Yeah'), ('Foo ', 'Yeah'),
('User-agent', 'Python-urllib/3.3'), ('Host', 'www.example.com')]
I will check for making a patch tomorrow.
----------
components: Library (Lib)
messages: 183234
nosy: karlcow, orsenthil
priority: normal
severity: normal
status: open
title: urllib.request add_header() currently allows trailing spaces
versions: Python 3.3
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Python tracker <[email protected]>
<http://bugs.python.org/issue17322>
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