net: recognize bare IPv6 loopback addresses in isLoopback

[watilde]

isLoopback() only matched bracket-wrapped IPv6 loopback addresses ([::1], [0:0:0:0:0:0:0:1]), but not the bare forms (::1, 0:0:0:0:0:0:0:1) that can appear when callers strip the brackets before passing the host string.

This change adds the two bare forms to the check so isLoopback returns true regardless of whether the IPv6 address is bracket-wrapped or not.

[nodejs-github-bot]

Review requested:

• @nodejs/net

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.14%. Comparing base (db3a8d8) to head (467c34b).
⚠️ Report is 550 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #63619   +/-   ##
=======================================
  Coverage   90.14%   90.14%           
=======================================
  Files         741      741           
  Lines      242133   242135    +2     
  Branches    45568    45559    -9     
=======================================
+ Hits       218265   218269    +4     
+ Misses      15371    15364    -7     
- Partials     8497     8502    +5     

Files with missing lines	Coverage Δ
lib/internal/net.js	100.00% <100.00%> (ø)

... and 26 files with indirect coverage changes

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[Ethan-Arrowood]

I believe this change is a valid patch. Can you update the PR description? And maybe add some cases to th eloopbackNot array like ::2 and 0:0:0:0:0:0:0:2 ?

[watilde]

@Ethan-Arrowood Thanks for your comment, I've updated.

[Ethan-Arrowood]

lgtm

[nodejs-github-bot]

Commit Queue failed

   ⚠  Commits were pushed after the last Full PR CI run:
   ⚠  - net: recognize bare IPv6 loopback addresses in isLoopback
   ⚠  - test: add non-loopback IPv6 cases to isLoopback test
   ✘  6 failure(s) on the last Jenkins CI run

The pull request was removed from the Commit Queue and labeled commit-queue-failed An error occurred while landing this pull request using GitHub Actions. . After resolving the failure, remove that label and add commit-queue Add this label to land a pull request using GitHub Actions. to retry.

Full Commit Queue output

- Loading data for nodejs/node/pull/63619
✔  Done loading data for nodejs/node/pull/63619
----------------------------------- PR info ------------------------------------
Title      net: recognize bare IPv6 loopback addresses in isLoopback (#63619)
Author     Daijiro Wachi <daijiro.wachi@gmail.com> (@watilde)
Branch     watilde:fixes-net -> nodejs:main
Labels     net, author ready, needs-ci, commit-queue, commit-queue-squash
Commits    2
 - net: recognize bare IPv6 loopback addresses in isLoopback
 - test: add non-loopback IPv6 cases to isLoopback test
Committers 1
 - Daijiro Wachi <daijiro.wachi@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/63619
Reviewed-By: Ethan Arrowood <ethan@arrowood.dev>
Reviewed-By: James M Snell <jasnell@gmail.com>
------------------------------ Generated metadata ------------------------------
PR-URL: https://github.com/nodejs/node/pull/63619
Reviewed-By: Ethan Arrowood <ethan@arrowood.dev>
Reviewed-By: James M Snell <jasnell@gmail.com>
--------------------------------------------------------------------------------
   ℹ  This PR was created on Thu, 28 May 2026 13:22:55 GMT
   ✔  Approvals: 2
   ✔  - Ethan Arrowood (@Ethan-Arrowood): https://github.com/nodejs/node/pull/63619#pullrequestreview-4695314656
   ✔  - James M Snell (@jasnell) (TSC): https://github.com/nodejs/node/pull/63619#pullrequestreview-4749855586
   ✔  Last GitHub CI successful
   ℹ  Last Full PR CI on 2026-07-21T00:52:57Z: https://ci.nodejs.org/job/node-test-pull-request/74934/
   ⚠  Commits were pushed after the last Full PR CI run:
   ⚠  - net: recognize bare IPv6 loopback addresses in isLoopback
   ⚠  - test: add non-loopback IPv6 cases to isLoopback test
- Querying data for job/node-test-pull-request/74934/
✔  Build data downloaded
- Querying failures of job/node-test-commit/89607/
✔  Data downloaded
   ✘  6 failure(s) on the last Jenkins CI run
--------------------------------------------------------------------------------
   ✔  Aborted `git node land` session in /home/runner/work/node/node/.ncu

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