Allowed a left byte of zero in mixed IPv4/IPv6 validation

[bshen]

Basically, IPv4-mapped IPv6 addresses in the CIDR block ::ffff:0.0.0.0/104 are validated as invalid when unpack_ipv4=False, yet is valid when the first IPv4 octet is non-zero or when unpack_ipv4=True.

# my.app.models
# Django==1.8.6
from django.db import models

class TestIPNoUnpack(models.Model):
    ip = models.GenericIPAddressField(null=False, protocol='both', unpack_ipv4=False)


class TestIPUnpack(models.Model):
    ip = models.GenericIPAddressField(null=False, protocol='both', unpack_ipv4=True)



> python manage.py shell

In [1]: from my.app.models import TestIPNoUnpack, TestIPUnpack

In [2]: testipunpack = TestIPUnpack(ip='::ffff:0.0.0.0')

In [3]: testipunpack.clean_fields()

In [4]: testipunpack.ip
Out[4]: '0.0.0.0'

In [5]: testipnounpack = TestIPNoUnpack(ip='::ffff:0.0.0.0')

In [6]: testipnounpack.clean_fields()

ValidationError: {'ip': [u'Enter a valid IPv4 or IPv6 address.']}

In [7]: testipnounpack2 = TestIPNoUnpack(ip='::ffff:0.255.255.255')

In [8]: testipnounpack2.clean_fields()

ValidationError: {'ip': [u'Enter a valid IPv4 or IPv6 address.']}

In [9]: testipnounpack3 = TestIPNoUnpack(ip='::ffff:1.0.0.0')

In [10]: testipnounpack3.clean_fields()

In [11]: testipnounpack3.ip
Out[11]: '::ffff:1.0.0.0'

[Tim Graham]

​PR

[bshen]

Is this the actual desired behavior? I don't think we want to have mixed IPv4 and IPv6 representation be invalid when unpack_ipv4 is False. Mixed IPv4 and IPv6 is still valid IPv6. In fact, this would probably break existing code written by others that depends on this functionality where the first IPv4 octet is not 0.

Furthermore, it appears that root cause of the inconsistency is not addressed, but rather a whole class of valid IPv6 addresses is now marked invalid.

[Amine Yaiche]

You are completely right. My apologies for the inconvenience. I was looking at the wrong problem.

[bshen]

This looks like the correct fix. Thanks for responding and fixing it quickly!

[Tim Graham]

Hi Amine, just wanted to mention for future reference that you don't need to attach a patch here when you also send a pull request.

[Tim Graham <timograham@…>]

In 32c8e43e:

Fixed #26378 -- Allowed a left byte of zero in mixed IPv4/IPv6 validation.