ipaddress.IPv4Network allows prefix > 32

[JohnFlorian]

BPO	35989
Nosy	@pitrou, @matrixise, @jheiv, @remilapeyre, @tirkarthi
PRs	bpo-35989: Forbid a netmask > 32 for ipaddress.IPv4Network #11844

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

Show more details

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-02-13.16:13:55.267>
labels = ['3.7', 'type-bug', 'library']
title = 'ipaddress.IPv4Network allows prefix > 32'
updated_at = <Date 2019-05-18.12:19:37.025>
user = 'https://bugs.python.org/JohnFlorian'

bugs.python.org fields:

activity = <Date 2019-05-18.12:19:37.025>
actor = 'xtreak'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-02-13.16:13:55.267>
creator = 'John Florian'
dependencies = []
files = []
hgrepos = []
issue_num = 35989
keywords = ['patch']
message_count = 5.0
messages = ['335460', '335475', '337228', '337230', '342795']
nosy_count = 6.0
nosy_names = ['pitrou', 'matrixise', 'jedwards', 'John Florian', 'remi.lapeyre', 'xtreak']
pr_nums = ['11844']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue35989'
versions = ['Python 3.7']

[JohnFlorian]

I wanted a simple is_valid_ipv4_network() function, so I wrote one and a bunch of unit tests where I discovered that I can legally:

>>> n = IPv4Network(('192.168.123.234', 12345678))
>>> n
IPv4Network('192.168.123.234/12345678')
>>> n.prefixlen
12345678
>>> n.max_prefixlen
32

I assume this is a bug.

[matrixise]

I proposed my PR but I prefer a review because in the code of ipaddress, there is a function for the validation of an address with the netmask. Maybe we could use this function and try to refactor/improve the current code.

[remilapeyre]

Hi @maxtrixise, thanks for PR,

there is a function for the validation of an address with the netmask

Which one do you want to use?

[jheiv]

It may be worth also addressing the fact that IPv6Network makes no restriction on it's netmask (when specified as a tuple).

[tirkarthi]

See also bpo-36845 that seems to have fixed this.

[furkanonder]

See also bpo-36845 that seems to have fixed this.

Yes, the issue seems to be solved. I think we can close the issue.

>>> from ipaddress import IPv4Network
>>> n = IPv4Network(('192.168.123.234', 12345678))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.11/ipaddress.py", line 1513, in __init__
    self.netmask, self._prefixlen = self._make_netmask(mask)
                                    ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/ipaddress.py", line 1170, in _make_netmask
    cls._report_invalid_netmask(prefixlen)
  File "/usr/lib/python3.11/ipaddress.py", line 472, in _report_invalid_netmask
    raise NetmaskValueError(msg) from None
ipaddress.NetmaskValueError: 12345678 is not a valid netmask
>>> 

[devdanzin]

Seems completely fixed by #13298.