urlencode produces bad output from ssl.CERT_NONE and friends that chokes decoders

[vitaly-krugl]

BPO	33025
Nosy	@warsaw, @tiran, @ethanfurman, @vitaly-krugl

^{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/ethanfurman'
closed_at = None
created_at = <Date 2018-03-08.06:57:47.318>
labels = ['3.8', 'type-bug', 'library', '3.9', '3.10']
title = 'urlencode produces bad output from ssl.CERT_NONE and friends that chokes decoders'
updated_at = <Date 2021-06-29.20:16:30.558>
user = 'https://github.com/vitaly-krugl'

bugs.python.org fields:

activity = <Date 2021-06-29.20:16:30.558>
actor = 'barry'
assignee = 'ethan.furman'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2018-03-08.06:57:47.318>
creator = 'vitaly.krug'
dependencies = []
files = []
hgrepos = []
issue_num = 33025
keywords = []
message_count = 5.0
messages = ['313424', '313732', '391439', '391440', '391441']
nosy_count = 4.0
nosy_names = ['barry', 'christian.heimes', 'ethan.furman', 'vitaly.krug']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue33025'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

[vitaly-krugl]

In [9]: from urllib.parse import urlencode, parse_qs

In [10]: import ast, ssl

In [11]: d = dict(cert_reqs=ssl.CERT_NONE)

In [12]: urlencode(d)
Out[12]: 'cert_reqs=VerifyMode.CERT_NONE'

In [25]: parse_qs('cert_reqs=VerifyMode.CERT_NONE')
Out[25]: {'cert_reqs': ['VerifyMode.CERT_NONE']}
In [29]: ast.literal_eval('VerifyMode.CERT_NONE')
Traceback (most recent call last)
...
ValueError: malformed node or string: <_ast.Attribute object at 0x105c22358>

This used to work fine and produce 'cert_reqs=0' on Python 2.7, allowing it to be decoded properly downstream. However, 'cert_reqs=VerifyMode.CERT_NONE' can't be decoded generically. So, something it's that used to work in prior python versions that is breaking now.

Additional information. json.dumps() actually dumps that value as a number instead of 'VerifyMode.CERT_NONE'.

It appears that urlencode doesn't work properly with enums, where I would expect it to emit the numeric value of the enum.

[tiran]

Ethan, please take a look.

[ethanfurman]

IIUC, the issue is that

  urlencode( {'cert_reqs': ssl.CERT_NONE} )

no longer produces

'cert_reqs=0'

?

[tiran]

I guess so.

We turned CERT_NONE into an IntFlag enum many years ago. urlencode() uses repr to convert integer enums.

[ethanfurman]

Actually, I think it uses str(). An easy fix would be to use format() for all non-bytes objects instead -- the question then becomes how many objects (besides Enums with mixed-in data types) have a different str() vs format() display?