email.utils.parsedate_tz raises UnboundLocalError if time has more than 2 dots in it

[benhoyt]

BPO	45239
Nosy	@warsaw, @benhoyt, @ambv, @miss-islington
PRs	bpo-45239: Fix parsedate_tz when time has more than 2 dots in it #28452 [3.9] bpo-45239: Fix parsedate_tz when time has more than 2 dots in it (GH-28452) #28928 [3.10] bpo-45239: Fix parsedate_tz when time has more than 2 dots in it (GH-28452) #28930

^{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 = None
closed_at = <Date 2021-10-13.17:12:48.420>
created_at = <Date 2021-09-18.22:35:53.284>
labels = ['type-bug', 'library', '3.10', '3.11']
title = 'email.utils.parsedate_tz raises UnboundLocalError if time has more than 2 dots in it'
updated_at = <Date 2021-10-13.17:12:48.418>
user = 'https://github.com/benhoyt'

bugs.python.org fields:

activity = <Date 2021-10-13.17:12:48.418>
actor = 'lukasz.langa'
assignee = 'none'
closed = True
closed_date = <Date 2021-10-13.17:12:48.420>
closer = 'lukasz.langa'
components = ['Library (Lib)']
creation = <Date 2021-09-18.22:35:53.284>
creator = 'benhoyt'
dependencies = []
files = []
hgrepos = []
issue_num = 45239
keywords = ['patch']
message_count = 6.0
messages = ['402140', '402141', '403847', '403852', '403856', '403857']
nosy_count = 4.0
nosy_names = ['barry', 'benhoyt', 'lukasz.langa', 'miss-islington']
pr_nums = ['28452', '28928', '28930']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue45239'
versions = ['Python 3.10', 'Python 3.11']

[benhoyt]

In going through some standard library code, I found that the email.utils.parsedate_tz() function (https://docs.python.org/3/library/email.utils.html#email.utils.parsedate_tz) has a bug if the time value is in dotted format and has more than 2 dots in it, for example: "12.34.56.78". Per the docs, it should return None in the case of invalid input.

This is happening because in the case that handles the '.' separator (instead of the normal ':'), there's no else clause to return None when there's not 2 or 3 segments.

From

cpython/Lib/email/_parseaddr.py

Lines 118 to 132 in dea59cf

	if len(tm) == 2:
	[thh, tmm] = tm
	tss = '0'
	elif len(tm) == 3:
	[thh, tmm, tss] = tm
	elif len(tm) == 1 and '.' in tm[0]:
	# Some non-compliant MUAs use '.' to separate time elements.
	tm = tm[0].split('.')
	if len(tm) == 2:
	[thh, tmm] = tm
	tss = 0
	elif len(tm) == 3:
	[thh, tmm, tss] = tm
	else:
	return None

:

    if len(tm) == 2:
        [thh, tmm] = tm
        tss = '0'
    elif len(tm) == 3:
        [thh, tmm, tss] = tm
    elif len(tm) == 1 and '.' in tm[0]:
        # Some non-compliant MUAs use '.' to separate time elements.
        tm = tm[0].split('.')
        if len(tm) == 2:
            [thh, tmm] = tm
            tss = 0
        elif len(tm) == 3:
            [thh, tmm, tss] = tm
        # HERE: need "else: return None"
    else:
        return None

We simply need to include that additional "else: return None" block in the '.' handling case.

I'll submit a pull request that fixes this soon (and adds a test for this case).

[benhoyt]

For reference, here's a repro case:

$ python3.10 -c 'import email.utils; \
    email.utils.parsedate_tz("Wed, 3 Apr 2002 12.34.56.78+0800")'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.10/email/_parseaddr.py", line 50, in parsedate_tz
    res = _parsedate_tz(data)
  File "/usr/local/lib/python3.10/email/_parseaddr.py", line 134, in _parsedate_tz
    thh = int(thh)
UnboundLocalError: local variable 'thh' referenced before assignment

[ambv]

New changeset b9e6876 by Ben Hoyt in branch 'main':
bpo-45239: Fix parsedate_tz when time has more than 2 dots in it (GH-28452)
b9e6876

[ambv]

New changeset 5638618 by Miss Islington (bot) in branch '3.9':
bpo-45239: Fix parsedate_tz when time has more than 2 dots in it (GH-28452) (GH-28928)
5638618

[ambv]

New changeset f8473f6 by Łukasz Langa in branch '3.10':
[3.10] bpo-45239: Fix parsedate_tz when time has more than 2 dots in it (GH-28452) (GH-28930)
f8473f6

[ambv]

Thanks, Ben! ✨ 🍰 ✨