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Send repeated response headers as one line so Swoole keeps every value - #22
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Swoole keeps one value per header name: a second header() call for the same name replaces the first. sendResponseHeaders() called header() once per value, so a response with several Link, Vary or Cache-Control values reached the client with only the last one. In production a page carrying ten Link values (llms.txt, API catalog, MCP server card, agent skills, Vite preloads...) arrived with one, and Cloudflare Early Hints never had a preload link to cache. Repeated values now go out as one comma-separated field line (RFC 9110, section 5.3). Set-Cookie keeps its own path, one cookie() call per cookie. Verified on a real Swoole 6.3.0 server (PHP 8.3): before, Link carried only the last of three values; after, all three, with cookies and single-value headers unchanged.
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Problem
Swoole keeps one value per header name: a second
header()call for the same name replaces the first.SwooleClient::sendResponseHeaders()calledheader()once per value, so any repeated header (Link,Vary,Cache-Control…) reached the client with only its last value.Production impact (modelslab.com): the app sends 10
Linkvalues (llms.txt, llms-full.txt, api-catalog, OpenAPI, docs, MCP server card, agent skills, status, terms, privacy) plus Vitepreloadlinks; responses arrived with only</privacy-policy>; rel="privacy-policy". Cloudflare Early Hints never got a preload link to cache, so all ~42,200 Early Hints lookups a day were cache misses (504s) and no 103 was ever sent.Fix
Send repeated values as one comma-separated field line (RFC 9110 §5.3).
Set-Cookieis excluded — it already goes out onecookie()call per cookie.Verification
phpswoole/swoole:php8.3, Swoole 6.3.0RC1, PHP 8.3.35), response with threeLinkvalues, a single header and two cookies:Link: </privacy-policy>; rel="privacy-policy"(last value only)Link: </build/app.css>; rel=preload; as=style, </llms.txt>; rel="llms-txt", </privacy-policy>; rel="privacy-policy";X-Singleand bothSet-Cookielines unchangedtests/Unit/SwooleClientResponseHeadersTest.php(3 tests): repeated values joined into one call, single values unchanged, cookies never joined. Reverting the fix fails the first test.main(no new errors); full matrix with Swoole runs in CI.Need help on this PR? Tag
@codesmith-botwith what you need.