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[socket] Fix IPv6 compilation error on host platform#14101

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swoboda1337 merged 1 commit intoesphome:devfrom
swoboda1337:fix/socket-ipv6-host-compilation
Feb 19, 2026
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[socket] Fix IPv6 compilation error on host platform#14101
swoboda1337 merged 1 commit intoesphome:devfrom
swoboda1337:fix/socket-ipv6-host-compilation

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@swoboda1337 swoboda1337 commented Feb 19, 2026

What does this implement/fix?

When network: enable_ipv6: true is set on the host platform, compilation fails because format_sockaddr_to in socket.cpp accesses sin6_addr.un.u32_addr — an LWIP-specific struct layout — under a #ifndef USE_SOCKET_IMPL_LWIP_TCP guard that includes the host platform. The host platform uses POSIX struct in6_addr which only has s6_addr (no LWIP union).

ESP32-IDF is unaffected despite also using BSD sockets, because its LWIP headers provide the un.u32_addr union layout.

The fix narrows the preprocessor guard to USE_HOST and uses the standard IN6_IS_ADDR_V4MAPPED() macro with s6_addr[] for the host code path only. The existing LWIP code path for ESP32-IDF and LWIP sockets is unchanged.

Also adds socket component build tests for host and ESP32-IDF, with and without IPv6.

Types of changes

  • Bugfix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • Developer breaking change (an API change that could break external components)
  • Code quality improvements to existing code or addition of tests
  • Other

Related issue or feature (if applicable):

Pull request in esphome-docs with documentation (if applicable):

  • N/A

Test Environment

  • ESP32
  • ESP32 IDF
  • ESP8266
  • RP2040
  • BK72xx
  • RTL87xx
  • LN882x
  • nRF52840

Example entry for config.yaml:

esphome:
  name: test-host-ipv6

host:

network:
  enable_ipv6: true

Checklist:

  • The code change is tested and works locally.
  • Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

@swoboda1337 @claude
[socket] Fix IPv6 compilation error on host platform
f24c178 
The format_sockaddr_to function accessed sin6_addr.un.u32_addr (an
LWIP-specific struct layout) under a guard that included the host
platform, which uses POSIX struct in6_addr without the LWIP union.

Narrow the preprocessor guard to USE_HOST and use the standard
IN6_IS_ADDR_V4MAPPED() macro with s6_addr[] for the host code path.
ESP32-IDF is unaffected since its LWIP headers provide the union layout
even with BSD sockets.

Also adds socket component build tests for host and ESP32-IDF, with and
without IPv6.

Closes esphome#14097

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Copilot AI review requested due to automatic review settings February 19, 2026 15:06
@swoboda1337 swoboda1337 requested a review from a team as a code owner February 19, 2026 15:06
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github-actions bot commented Feb 19, 2026

To use the changes from this PR as an external component, add the following to your ESPHome configuration YAML file:

external_components:
  - source: github://pr#14101
    components: [socket]
    refresh: 1h

(Added by the PR bot)

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github-actions bot commented Feb 19, 2026

👋 Hi there! This PR modifies 1 file(s) with codeowners.

@esphome/core - As codeowner(s) of the affected files, your review would be appreciated! 🙏

Note: Automatic review request may have failed, but you're still welcome to review.

@bdraco bdraco added this to the 2026.2.1 milestone Feb 19, 2026
Copilot AI reviewed Feb 19, 2026
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Pull request overview

This PR fixes a compilation error when using IPv6 on the host platform. The issue stems from the host platform using POSIX struct in6_addr (which only has s6_addr[]) while the existing code attempted to access LWIP-specific un.u32_addr union members. ESP32-IDF is unaffected because it includes LWIP headers that provide the union layout despite using BSD sockets.

Changes:

  • Updated IPv4-mapped IPv6 address detection to use standard POSIX macros for host platform
  • Added platform-specific preprocessor guards to separate host and ESP32-IDF code paths
  • Added build tests for socket component on host and ESP32-IDF platforms with and without IPv6

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file
File Description
esphome/components/socket/socket.cpp Added USE_HOST-specific code path using IN6_IS_ADDR_V4MAPPED() and s6_addr[12] for IPv4-mapped address detection
tests/components/socket/common.yaml Shared test configuration with substitution for IPv6 enable flag
tests/components/socket/test.host.yaml Build test for socket component on host platform without IPv6
tests/components/socket/test.esp32-idf.yaml Build test for socket component on ESP32-IDF platform without IPv6
tests/components/socket/test-ipv6.host.yaml Build test for socket component on host platform with IPv6 enabled
tests/components/socket/test-ipv6.esp32-idf.yaml Build test for socket component on ESP32-IDF platform with IPv6 enabled

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codecov-commenter commented Feb 19, 2026 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.11%. Comparing base (4d05e4d) to head (f24c178).
⚠️ Report is 7 commits behind head on dev.

Additional details and impacted files 
@@           Coverage Diff           @@
##              dev   #14101   +/-   ##
=======================================
  Coverage   74.11%   74.11%           
=======================================
  Files          55       55           
  Lines       11590    11590           
  Branches     1578     1578           
=======================================
  Hits         8590     8590           
  Misses       2598     2598           
  Partials      402      402

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

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swoboda1337 commented Feb 19, 2026

Thanks

@swoboda1337 swoboda1337 enabled auto-merge (squash) February 19, 2026 15:34
@swoboda1337 swoboda1337 merged commit 5304750 into esphome:dev Feb 19, 2026
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swoboda1337 added a commit that referenced this pull request Feb 20, 2026
@swoboda1337 @claude
[socket] Fix IPv6 compilation error on host platform (#14101)
2d2178c 
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
@swoboda1337 swoboda1337 mentioned this pull request Feb 20, 2026
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bugfix cherry-picked component: socket has-tests

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network: enabling IPv6 when using host platform results in uncaught error

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