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

maxmouchet · 2021-03-26T17:34:41Z

BPO	43633
Nosy	@opavlyuk, @maxmouchet
PRs	gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses #29345

^{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 2021-03-26.17:34:40.530>
labels = ['type-feature', 'library']
title = 'Improve the textual representation of IPv4-mapped IPv6 addresses'
updated_at = <Date 2021-11-01.12:05:04.773>
user = 'https://github.com/maxmouchet'

bugs.python.org fields:

activity = <Date 2021-11-01.12:05:04.773>
actor = 'opavlyuk'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-03-26.17:34:40.530>
creator = 'maxmouchet'
dependencies = []
files = []
hgrepos = []
issue_num = 43633
keywords = ['patch']
message_count = 2.0
messages = ['389556', '405434']
nosy_count = 2.0
nosy_names = ['opavlyuk', 'maxmouchet']
pr_nums = ['29345']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue43633'
versions = []

Linked PRs

maxmouchet · 2021-03-26T17:34:40Z

Python supports IPv4-mapped IPv6 addresses as defined by RFC 4038:
"the IPv6 address ::FFFF:x.y.z.w represents the IPv4 address x.y.z.w.”

The current behavior is as follows:

   from ipaddress import ip_address
   addr = ip_address('::ffff:8.8.4.4') # IPv6Address('::ffff:808:404')
   addr.ipv4_mapped # IPv4Address('8.8.4.4')

Note that the textual representation of the IPv6Address is *not* in IPv4-mapped format.
It prints ::ffff:808:404 instead of ::ffff:8.8.4.4.
This is technically correct, but it’s somewhat frustrating as it makes it harder to read IPv4s embedded in IPv6 addresses.

My proposal would be to check, in __str__, if an IPv6 is an IPv4-mapped, and to return the appropriate representation :

   from ipaddress import ip_address
   addr = ip_address('::ffff:8.8.4.4')

   # Current behavior
   str(addr)  # '::ffff:808:404'
   repr(addr) # IPv6Address('::ffff:808:404')

   # Proposed behavior
   str(addr)  # '::ffff:8.8.4.4'
   repr(addr) # IPv6Address('::ffff:8.8.4.4')

A few data points:

Julia prints ::ffff:808:404 (current behavior)
C (glibc) and ClickHouse prints ::ffff:8.8.4.4 (proposed behavior)

opavlyuk · 2021-11-01T12:05:05Z

@maxmouchet, thank you for creating the issue.
For me it makes sense, and RFC 4291 calls such IPv6 text representation approach as "more convenient".

I'll try to fix this, if you don't mind.
P.S.: Sorry for providing PR before I asked.

…esses (#29345) 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). --------- Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

asvetlov · 2023-07-31T14:52:02Z

Done by #29345

kellyjonbrazil · 2024-08-01T22:10:01Z

Are there any tests for the reverse_pointer method? I'm seeing strange results with the new behavior:

IP Address: ::FFFF:192.168.1.35

Results in a reverse_pointer of:

5.3...1...8.6.1...2.9.1.f.f.f.f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa

instead of the old:

3.2.1.0.8.a.0.c.f.f.f.f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa

I'm not sure which one is more valid or if a pointer record is even relevant in the context of mapped addresses. The original way seems more correct to me if nothing for the fact that there are strange extra dots in the new output.

(I'll create a new issue for this since this one is closed)

GH-123419) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (gh-87799)

…dresses (pythonGH-123419) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (pythongh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

…ddresses (GH-123419) (#123606) gh-123409: fix `IPv6Address.reverse_pointer` for IPv4-mapped addresses (GH-123419) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (gh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

…6 addresses (pythonGH-29345) 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). --------- (cherry picked from commit f22bf8e) Co-authored-by: opavliuk <40970635+opavlyuk@users.noreply.github.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

…v6 addresses (GH-29345) (GH-135080) 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). (cherry picked from commit f22bf8e) Co-authored-by: opavliuk <40970635+opavlyuk@users.noreply.github.com> Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

…v6 addresses (GH-29345) (GH-135081) 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). (cherry picked from commit f22bf8e) Co-authored-by: opavliuk <40970635+opavlyuk@users.noreply.github.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

…6 addresses (GH-29345) (GH-135078) 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). (cherry picked from commit f22bf8e) Co-authored-by: opavliuk <40970635+opavlyuk@users.noreply.github.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

…dresses (pythonGH-123419) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (pythongh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

…v6 addresses (GH-29345) (GH-135079) 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). (cherry picked from commit f22bf8e) Co-authored-by: opavliuk <40970635+opavlyuk@users.noreply.github.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

…dresses (pythonGH-123419) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (pythongh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

…ddresses (GH-123419) (GH-135088) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (gh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

…ddresses (GH-123419) (GH-135087) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (gh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

…ddresses (GH-123419) (GH-135086) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (gh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

…dresses (GH-123419) (GH-135085) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (gh-87799) (cherry picked from commit 77a2fb4) Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

oprypin · 2025-06-04T15:11:14Z

I'd like to express my concern that this change got backported to all these patch releases of Python. Surely the feature is not so important that everyone needs to get it immediately? Compared to the tradeoff that this is supposed to be bugfixes-only?

As I'm rushing to apply the latest security release, I see that the patch release also changed our code that produces IPv6 addresses to now produce ::ffff:7.8.9.10 instead of ::ffff:708:90a.

maxmouchet mannequin added stdlib Python modules in the Lib dir type-feature A feature request or enhancement labels Mar 26, 2021

ezio-melotti transferred this issue from another repository Apr 10, 2022

bewing mentioned this issue Oct 12, 2022

refactor: replace netaddr with ipaddress napalm-automation/napalm#1767

Merged

bedevere-bot mentioned this issue Apr 13, 2023

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

Merged

arhadthedev added the 3.13 bugs and security fixes label May 13, 2023

asvetlov closed this as completed Jul 31, 2023

PallHaraldsson mentioned this issue Apr 21, 2024

Improve the textual representation of IPv4-mapped IPv6 addresses JuliaLang/julia#54179

Open

kellyjonbrazil mentioned this issue Aug 1, 2024

Python 3.13 test failure: test_ip_address_ipv6_ipv4_mapped kellyjonbrazil/jc#582

Closed

kellyjonbrazil mentioned this issue Aug 1, 2024

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

Closed

kellyjonbrazil mentioned this issue Aug 27, 2024

Incorrect ipaddress.ip_address.reverse_pointer with improved textual representation of IPv4-mapped IPv6 addresses #123409

Closed

encukou pushed a commit that referenced this issue Sep 2, 2024

gh-123409: fix IPv6Address.reverse_pointer for IPv4-mapped addresses (

77a2fb4

GH-123419) Fix functionality that was broken with better textual representation for IPv4-mapped addresses (gh-87799)

miss-islington mentioned this issue Sep 2, 2024

[3.13] gh-123409: fix IPv6Address.reverse_pointer for IPv4-mapped addresses (GH-123419) #123606

Merged

This was referenced Jun 3, 2025

[3.9] gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses (GH-29345) #135078

Merged

[3.10] gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses (GH-29345) #135079

Merged

This was referenced Jun 3, 2025

[3.11] gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses (GH-29345) #135080

Merged

[3.12] gh-87799: Improve the textual representation of IPv4-mapped IPv6 addresses (GH-29345) #135081

Merged

miss-islington mentioned this issue Jun 3, 2025

[3.9] gh-123409: fix IPv6Address.reverse_pointer for IPv4-mapped addresses (GH-123419) #135085

Merged

miss-islington mentioned this issue Jun 3, 2025

[3.12] gh-123409: fix IPv6Address.reverse_pointer for IPv4-mapped addresses (GH-123419) #135086

Merged

miss-islington mentioned this issue Jun 3, 2025

[3.11] gh-123409: fix IPv6Address.reverse_pointer for IPv4-mapped addresses (GH-123419) #135087

Merged

miss-islington mentioned this issue Jun 3, 2025

[3.10] gh-123409: fix IPv6Address.reverse_pointer for IPv4-mapped addresses (GH-123419) #135088

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Uh oh!

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

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

maxmouchet mannequin commented Mar 26, 2021 •

edited by bedevere-app bot

Loading

maxmouchet mannequin commented Mar 26, 2021

Uh oh!

opavlyuk mannequin commented Nov 1, 2021

Uh oh!

asvetlov commented Jul 31, 2023

Uh oh!

kellyjonbrazil commented Aug 1, 2024 •

edited

Loading

Uh oh!

oprypin commented Jun 4, 2025

Uh oh!

Uh oh!

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

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

Comments

maxmouchet mannequin commented Mar 26, 2021 • edited by bedevere-app bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Linked PRs

maxmouchet mannequin commented Mar 26, 2021

Uh oh!

opavlyuk mannequin commented Nov 1, 2021

Uh oh!

asvetlov commented Jul 31, 2023

Uh oh!

kellyjonbrazil commented Aug 1, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

oprypin commented Jun 4, 2025

Uh oh!

maxmouchet mannequin commented Mar 26, 2021 •

edited by bedevere-app bot

Loading

kellyjonbrazil commented Aug 1, 2024 •

edited

Loading