Patch attached with test.

In summary:

A request to the url b'/\x80' appears to the application as a request to b'\xc2\x80' -- The issue being the latin1 decoded PATH_INFO is re-encoded as UTF-8 and then decoded as latin1

(on the wire) b'\x80' -(decode latin1)-> u'\x80' -(encode utf-8)-> b'\xc2\x80' -(decode latin1)-> b'\xc2\x80'

My patch cuts out the encode(utf-8)->decode(latin1)

A few typos in my previous comment, pressed enter too quickly, here's an updated comment:

Patch attached with test.

In summary:

A request to the url b'/\x80' appears to the application as a request to b'/\xc2\x80' -- The issue being the latin1 decoded PATH_INFO is re-encoded as UTF-8 and then decoded as latin1

    (on the wire) b'\x80' -(decode latin1)-> u'\x80' -(encode utf-8)-> b'\xc2\x80' -(decode latin1)-> u'\xc2\x80'

My patch cuts out the encode(utf-8)->decode(latin1):

    (on the wire) b'\x80' -(decode latin1) -> u'\x80'

Oops, broke b'/%80'.

Here's a better fix that now takes:

    (on the wire) b'\x80' -(decode latin1)-> u'\x80' -(encode utf-8)-> b'\xc2\x80' -(decode latin1)-> u'\xc2\x80'

to:

    (on the wire) b'\x80' -(decode latin1)-> u'\x80' -(encode latin1) -> b'\x80' -(decode latin1)-> u'\x80'

I was going to say your original fix was the reverse of a change in r86146. But you seem to be fixing the problems before I express them :)

For the fix I would suggest something like unquote(path, "latin-1") would be simpler. I left some other review comments about the tests.

Updates after review.

Thanks, this version looks pretty good to me.

Forgot to remove the pyver code (leaning a bit too much on pre-commit)

New changeset 1f2cfcd5a83f by Martin Panter in branch '3.5':
Issue #26717: Stop encoding Latin-1-ized WSGI paths with UTF-8
https://hg.python.org/cpython/rev/1f2cfcd5a83f

New changeset 815a4ac67e68 by Martin Panter in branch 'default':
Issue #26717: Merge wsgiref fix from 3.5
https://hg.python.org/cpython/rev/815a4ac67e68

Why wsgiref uses latin1? It must use utf-8.

PEP3333 states that environ variables are str variables decoded using
latin1:
https://www.python.org/dev/peps/pep-3333/#id19

Therefore, to get the original bytes, one must encode using latin1
On Apr 20, 2016 3:46 AM, "Александр Эри" <report@bugs.python.org> wrote:

>
> Александр Эри added the comment:
>
> Why wsgiref uses latin1? It must use utf-8.
>
> ----------
> keywords: +patch
> nosy: +Александр Эри
> Added file: http://bugs.python.org/file42531/simple_server.py.diff
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <http://bugs.python.org/issue26717>
> _______________________________________
>