Preserve all X-Forwarded-For header lines - #581
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Correct fix, LGTM.
Header.Get → strings.Join(Header.Values(…), ", ") is the standard Go idiom for folding multi-line headers and directly addresses the regression from the Director→Rewrite migration in #573. No behavioral change for the single-header case. The new test cleanly reproduces the bug.
Minor note (not a blocker): X-Forwarded-Proto and X-Forwarded-Host at proxy.go:150,153 use the same Header.Get pattern. Less likely to arrive as multiple lines in practice, but worth a follow-up issue if that's plausible in your deployment topology.
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Fixes #580
Summary
Restores handling of
X-Forwarded-Forwhen it arrives as multiple header lines by joiningHeader.Values("X-Forwarded-For")instead of reading only the first line viaHeader.Get, a regression introduced with theDirector→Rewritemigration in #573. Fixes #580.Backward Compatibility
Breaking Change? No
Note on AI Usage
Parts of this code and tests were developed with assistance from Claude Code (claude-opus-4.8).