urlapi: handle redirect without set scheme with default-scheme

[bagder]

Reported-by: mulan_dh on hackerone

[testclutch]

Analysis of PR #21632 at a6650300:

Test 2402 failed, which has NOT been flaky recently, so there could be a real issue in this PR. Note that this test has failed in 12 different CI jobs (the link just goes to one of them). Note that this CI job has had a number of other flaky tests recently (2, to be exact) so it may be that this failure is rather a systemic issue with this job and not with this specific PR.

Generated by Testclutch

[Copilot]

Pull request overview

This PR updates URL API redirect handling so a relative redirect can be applied when the URL handle has no stored scheme but CURLU_DEFAULT_SCHEME is in use.

Changes:

• Falls back to DEFAULT_SCHEME when computing redirect URL offsets if u->scheme is unset.
• Adds a new libtest regression case for default-scheme redirects.
• Registers the new test source and test data.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
lib/urlapi.c	Uses the default scheme when deriving the protocol separator during relative redirect handling.
tests/libtest/lib1921.c	Adds a regression test for redirecting a URL handle without a stored scheme.
tests/libtest/Makefile.inc	Adds lib1921.c to the libtest build list.
tests/data/test1921	Defines the new URL API regression test.
tests/data/Makefile.am	Adds test1921 to the test data list.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.