Synchronous HTTP/1.1

std/http owns validated HTTP/1.1 message values, the protocol's single transport-independent framing authority, and a synchronous one-request-per-connection client. The client composes the public URL, name-resolution, TCP, and I/O contracts; the codec remains independent of sockets, descriptors, DNS, and connection policy.

Request owns a parsed Url, method, ordered user fields, and complete byte body. Client adds a canonical Host, Connection: close, and one computed Content-Length. Callers cannot supply those fields or Transfer-Encoding, so request framing has one authority. HTTPS is rejected before name resolution because this release has no TLS transport. CONNECT is rejected because the API does not transfer tunnel ownership.

Client.send opens one connection and returns a uniquely owned Response. Ordinary informational responses are consumed before the final response is exposed; protocol-switching status 101 is rejected because the API does not transfer the upgraded stream. Response exposes the final status and fields and implements Reader for decoded body bytes. Completion, decoding or network failure, explicit close, and destruction of an unfinished response all close the connection. There is no pooling, redirect following, request replay, decompression, or connection reuse.

send_with_timeout applies one duration to the host-connection deadline and then as the timeout of each stream read and write operation. It is not a wall-clock deadline for the complete response.

Method preserves the exact case-sensitive token. HeaderName accepts the HTTP token alphabet, stores one lowercase canonical spelling, and hashes that canonical identity. HeaderValue stores exact bytes after removing wire optional whitespace at its edges; CR, LF, NUL, and other forbidden controls are rejected. Headers is ordered and preserves duplicates instead of silently combining fields.

RequestHead accepts only non-empty ASCII origin-form targets beginning with /; percent escapes must be complete hexadecimal triplets and characters outside the path/query grammar are rejected. The private wire encoder adds exactly one Content-Length selected from the bounded body and rejects caller fields that could introduce a second framing interpretation.

The response-head decoder accepts only HTTP/1.1 status lines and strict CRLF field lines. It owns its scan cursor, completed fields, framing evidence, and informational-response count across transport reads. Bytes and fields already accepted are therefore not rescanned or reconstructed when the next fragment arrives. It rejects obsolete line folding. It selects body framing once: HEAD, informational, 204, and 304 responses are bodyless; a supported final Transfer-Encoding selects chunked framing; one unambiguous Content-Length selects fixed framing; otherwise connection closure delimits the body. Equal comma-separated or repeated content lengths are accepted as one value. Conflicting lengths, simultaneous transfer encoding and content length, repeated chunked codings, unsupported codings, invalid decimal or hexadecimal sizes, and overflow are stable errors.

Chunk extensions follow the token and quoted-string grammar even though their values are ignored. Trailer fields are syntax-checked and bounded but are not merged into the response head; Content-Length and Transfer-Encoding are forbidden in trailers so framing cannot be revised after body bytes have been exposed.

Body decoding writes into caller-provided storage. Partial start lines, fields, chunk-size lines, chunk data, delimiters, and trailers retain an explicit incomplete state; they are never treated as end of input. Fixed and chunked bodies report premature EOF. Close-delimited bodies complete only when the transport reports EOF. The selected framing and its limit set enter one private body decoder together, so a transport consumer cannot reinterpret either decision.

Limits bounds the start line, each aggregate head, field count, informational-response count, individual field or trailer line, chunk-size line, and decoded body. The decoder checks these bounds before protocol-controlled growth. Bounding both each head and the number of informational heads also bounds their cumulative retained input and field storage. The standard defaults permit an 8 KiB start line, 64 KiB per head, 128 fields, 16 informational responses, 8 KiB field lines, 1 KiB chunk lines, and a 64 MiB decoded body.

The checked declarations in the module contract are the API authority.