Module http_server 

HTTP serve loop with connection limits (issue #3065).

serve replaces axum::serve. axum gives no access to the hyper builder. Thus axum cannot set a header-read timeout, a header size limit or an HTTP/2 stream limit. This loop applies HttpLimits from [server.http]. With default limits it behaves like axum::serve.

Timers

Each connection is in one of three phases:

• Head: the connection opened and no request arrived yet. header_read_timeout applies (if it is not set, keep_alive_timeout).
• Busy: at least one request is in flight. No timer applies. The request timeout layer limits handlers.
• Idle: no request in flight. keep_alive_timeout applies.

In every phase, an open head also starts header_read_timeout, and suspends the idle timer. The timer starts at the first byte of the head. More bytes do not restart it, so a slowloris client cannot keep the connection open. To find heads, the read path scans the client bytes:

• HTTP/1: a small framer skips bodies (Content-Length, chunked). A head runs from its first byte to its blank line, also when it is pipelined behind another request. CRLF between messages does not open a head.
• HTTP/2: a head is a header block (HEADERS and CONTINUATION frames, up to the payload of the END_HEADERS frame). Control frames (for example PING) do not open one.

The timers also run during a graceful drain.

Drain of a fresh connection

A connection that has received no request is not closed at the drain signal. Its request can be in flight, and a close would reset it. The server waits up to FRESH_CONN_GRACE (2 s) for the first request, or until the head timer ends. Then it starts the drain. Setup of an accepted connection (the make-service) gets the same grace after a shutdown, so a stuck one cannot hang the drain.

Structs

HttpLimits

Resolved [server.http] limits. 0 in the config means “off”.

IncomingStream

One accepted connection, given to the make-service.

KeepTunnel

Keeps an HTTP/2 WebSocket connection out of its idle timer.

Functions

serve

Serve make_service on listener until signal resolves, then drain.