[tanjiroK-coder]

Transfer-Encoding not recognized as chunked falls back to Content-Length

_httpUpdate keeps trailing whitespace on header values and httpGetLength only matches a Transfer-Encoding of exactly chunked, so Transfer-Encoding: chunked (trailing space) or two Transfer-Encoding headers (joined to chunked, chunked) are framed by Content-Length instead. A front end that follows RFC 9112 sees a chunked body, while a libcups server (ippeveprinter, PAPPL) reads Content-Length bytes and parses the rest of the chunk as the next request on the connection (TE.CL request smuggling).

Repro against master: POST with Transfer-Encoding: chunked , Content-Length: 4 and a chunk containing GET /smuggled HTTP/1.1. The body comes back as the 4 bytes 23\r\n and the next httpReadRequest returns GET /smuggled. With this change trailing OWS is trimmed (RFC 9110 section 5.5) and any other Transfer-Encoding is treated as a bad length rather than ignored (RFC 9112 section 6.1). The new testhttp cases fail 3 of 4 on master and pass here; the tools tests still pass.