gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses #29345

opavlyuk · 2021-10-31T15:52:09Z

https://bugs.python.org/issue43633

Issue: Improve the textual representation of IPv4-mapped IPv6 addresses #87799

opavlyuk · 2021-11-09T14:05:37Z

@maxmouchet, @ykvch guys, please take a look on this PR when you get a chance.
I'll greatly appreciate initial review, before someone from core developers gets here.

maxmouchet · 2021-11-09T20:45:50Z

Thanks for tackling this! This looks good to me.

Maybe the __str__ method could be simplified a little as I think (need to find a source) that an IPv4-mapped IPv6 address will never have a scope identifier.

opavlyuk · 2021-11-10T10:04:00Z

Maybe the __str__ method could be simplified a little as I think (need to find a source) that an IPv4-mapped IPv6 address will never have a scope identifier.

Thanks! Lets discuss it.
Indeed, according to RFC 4007 Section 11.1, IPv6 address 'scoped' format is meaningless and should not be used for global addresses.
At the same time,

This document, however, does not prohibit an implementation from using the format for those special addresses for implementation dependent purposes.

In addition, RFC 4007 Section 4 says that

[1] defines IPv6 addresses with embedded IPv4 addresses as being part
of global addresses. Thus, those addresses have global scope, with
regard to the IPv6 scoped address architecture. However, an
implementation may use those addresses as if they had other scopes
for convenience. For instance, [6] assigns link-local scope to IPv4
auto-configured link-local addresses (the addresses from the prefix
169.254.0.0/16 [7]) and converts those addresses into IPv4-mapped
IPv6 addresses in order to perform destination address selection
among IPv4 and IPv6 addresses. This would implicitly mean that the
IPv4-mapped IPv6 addresses equivalent to the IPv4 auto-configuration
link-local addresses have link-local scope. This document does not
preclude such a usage, as long as it is limited within the
implementation.

That is all I managed to find regarding the subject.

Please, let me know what you think about it.

opavlyuk · 2021-11-10T11:39:35Z

Noticed, that ipaddress.IPv6Address.exploded behavior differs from expected after the patch:

>>> addr = IPv6Address('::ffff:8.8.4.4')
# Expected
>>> addr.exploded
'0000:0000:0000:0000:0000:ffff:8.8.4.4'
# Actual
>>> addr.exploded
'0000:0000:0000:0000:0000:ffff:0808:0404'

I'm in progress fixing that.

github-actions · 2021-12-11T00:06:07Z

This PR is stale because it has been open for 30 days with no activity.

MaxwellDupre

Ran 203 tests in 0.198s

OK

== Tests result: SUCCESS ==
And I get:
>>> addr.exploded '0000:0000:0000:0000:0000:ffff:8.8.4.4'
Looks good to me.

cpython-cla-bot · 2022-05-03T16:54:16Z

All commit authors signed the Contributor License Agreement.

…esses Represent IPv4-mapped IPv6 address as x:x:x:x:x:x:d.d.d.d, where the 'x's are the hexadecimal values of the six high-order 16-bit pieces of the address, and the 'd's are the decimal values of the four low-order 8-bit pieces of the address (standard IPv4 representation).

arhadthedev · 2023-04-13T11:11:27Z

@opavlyuk Could you sign the new CLA by clicking not signed button in the cpython-cla-bot's message, please?

opavlyuk · 2023-04-13T12:07:31Z

@arhadthedev Thanks for letting me know! I initially used the wrong SSH key for the commits, but I've fixed it and the CLA is now marked as signed.
Could you suggest what should I do next to move forward with this PR? Should I contact the python-dev mailing list or take any other steps?

arhadthedev · 2023-04-13T12:21:58Z

For now, we need to wait.

Until 3.12b1 is out next month, core devs with network expertise can be busy with release blockers and PEP-grade features
Core devs need time to process through their unread notification queue after work (a couple of days or so, maybe sooner, it depends)
There is a feedback gathering month to give everybody a chance to participate in the PR.

opavlyuk · 2023-04-13T12:31:08Z

@arhadthedev Thanks for clearing things up! Then I'll watch out for the 3.12b1 release and return to the PR once all obstacles are cleared.
It's been waiting here for a while, so I'd like to kindly help it move along when the time is right 🙂

opavlyuk · 2023-05-16T09:44:09Z

@arhadthedev it appears a month has passed since the last update to the PR, during which time we haven't received further feedback. Also, I noticed that version 3.12.0a7 was released just yesterday.
I understand everyone is likely quite busy. Given these circumstances, do you think it might be appropriate to send a gentle reminder to our PR, in order to possibly draw the attention of the core developers?

opavlyuk · 2023-06-01T09:32:19Z

@encukou as you may recall, we had a conversation during PyCon SK 2022 where you kindly offered your guidance and support. I'm now writing to kindly ask if you could take a look at this PR. I would greatly appreciate your review, or if you could suggest someone who might be the right person for this task. Thank you for your time and consideration!

opavlyuk · 2023-07-06T13:17:12Z

@asvetlov could you please review this PR at your earliest convenience?
I understand that the ipaddress module has been without a maintainer for a while 😞
I'd appreciate if you could either take a look yourself or recommend someone appropriate for the task.

asvetlov · 2023-07-30T13:24:07Z

The patch is good but I see a small problem.

>>> from ipaddress import IPv6Address
>>> str(IPv6Address("::1.2.3.4"))
'::102:304'

According to RFC 4291 section 2.2 part 3 the representation should be ::13.1.68.3.

Did I miss something?

asvetlov · 2023-07-31T13:04:37Z

Ok, ::1.2.3.4 is not IPv4-Mapped IPv6 Address but IPv4-Compatible IPv6 Address.

The ipaddress library knows nothing about this subset of ipv6 addresses. I guess that the proper implementation should add .ipv4_compat property (similar to the already existing .ipv4_mapped) and check this property in __str()__ implementation.

It is doable but definitely not a part of this PR.

asvetlov · 2023-07-31T14:51:24Z

@opavlyuk thanks for the patch!

opavlyuk · 2023-07-31T15:00:00Z

@asvetlov Apologies for the delayed response - I've just returned to my laptop after a long weekend and unfortunately missed your earlier comments.
I appreciate your support and find collaborating with you an absolute pleasure!

opavlyuk · 2023-07-31T15:08:16Z

The ipaddress library knows nothing about this subset of ipv6 addresses. I guess that the proper implementation should add .ipv4_compat property (similar to the already existing .ipv4_mapped) and check this property in str() implementation.
It is doable but definitely not a part of this PR.

@asvetlov You're making good sense. Could you kindly provide some guidance on the best approach to address this, assuming it doesn't consume too much of your time?
Would it be proper to initiate a thread in python-ideas, or should we create a PR first before escalating the discussion? Perhaps there's an even more effective strategy?

asvetlov · 2023-08-01T12:21:44Z

I don't think that a thread in python-ideas will draw attention. It is a relatively rarely used thing.

You can just make a PR, and after a review it could be merged.

The PR should contain the new property definition, using it in all places where ipv4_mapped is accessed (__str__, .exploded, .is_private). Plus tests and documentation for the new property.

It doesn't sound like a lot of work.

the-knights-who-say-ni added the CLA signed label Oct 31, 2021

bedevere-bot added the awaiting review label Oct 31, 2021

📜🤖 Added by blurb_it.

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opavlyuk force-pushed the fix-issue-43633 branch from 3117395 to 03cefda Compare November 9, 2021 13:46

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opavlyuk force-pushed the fix-issue-43633 branch from 03cefda to b0f362c Compare January 5, 2022 16:55

MaxwellDupre approved these changes Mar 3, 2022

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opavlyuk added 3 commits April 13, 2023 12:59

bpo-43633 Update tests

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bpo-43633 Fix tests

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opavlyuk force-pushed the fix-issue-43633 branch from 68d0359 to 669cc90 Compare April 13, 2023 11:04

arhadthedev changed the title ~~bpo-43633 Improve the textual representation of IPv4-mapped IPv6 addresses~~ gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses Apr 13, 2023

arhadthedev added the stdlib Python modules in the Lib dir label Apr 13, 2023

Merge branch 'main' into fix-issue-43633

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Merge branch 'main' into fix-issue-43633

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asvetlov added 5 commits July 31, 2023 13:19

Add failed test

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Merge branch 'main' into fix-issue-43633

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User shorter variable names

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Revert test back

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Merge branch 'main' into fix-issue-43633

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asvetlov approved these changes Jul 31, 2023

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asvetlov added 2 commits July 31, 2023 15:28

Update 2021-10-31-16-06-28.bpo-43633.vflwXv.rst

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Update 2021-10-31-16-06-28.bpo-43633.vflwXv.rst

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asvetlov enabled auto-merge (squash) July 31, 2023 13:30

asvetlov merged commit f22bf8e into python:main Jul 31, 2023
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asvetlov mentioned this pull request Jul 31, 2023

Improve the textual representation of IPv4-mapped IPv6 addresses #87799

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This was referenced Aug 1, 2024

Python 3.13 test failure: test_ip_address_ipv6_ipv4_mapped kellyjonbrazil/jc#582

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Incorrect ipaddress.reverse_pointer with improved textual representation of IPv4-mapped IPv6 addresses #122589

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gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses #29345

gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses #29345

opavlyuk commented Oct 31, 2021 •

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gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses #29345

gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses #29345

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