CGI modules need automatic chunked transfer encoding with Keep-Alive

[mgrossmann]

Summary

CGI modules call http_printf() without setting Content-Length or Transfer-Encoding: chunked. With Connection: keep-alive, the browser waits until KEEPALIVE_TIMEOUT (~5s) because it has no way to know when the response body ends.

curl: no chunk, no close, no size. Assume close to signal end

Affected Modules

HTTPDMTT, HTTPDSRV, HTTPDM, HTTPJES2, HTTPDSL, HTTPLUA, HTTPREXX

mvsMF is not affected (sets Content-Length itself via sendDefaultHeaders()).

Root Cause

The chunked fallback is only implemented in httpget.c for static files. CGI modules take a different code path and don't get automatic chunked encoding.

Proposed Fix

The chunked fallback must happen at a central point — not just in httpget.c. When response headers have been sent without Content-Length or Transfer-Encoding, HTTPD must automatically insert Transfer-Encoding: chunked and set httpc->chunked = 1.

Option A: An http_end_headers() function that all code paths (httpget.c, CGI modules) pass through before sending body data. This function checks whether Content-Length or chunked is set, and inserts the chunked header if needed.

Option B: In httpsend.c — when the first data chunk is sent and neither content_length_set nor chunked is set, automatically send the Transfer-Encoding: chunked header and switch to chunked mode.

Important: HTTP/1.0 clients must not receive chunked encoding (as before).

Acceptance Criteria

• CGI responses include Transfer-Encoding: chunked
• Browser renders CGI pages immediately, no timeout waiting
• mvsMF continues to use Content-Length
• Static files continue to use Content-Length
• HTTP/1.0 clients do not receive chunked encoding