Running HTTP/2 client.

Client configuration

The default client config.

The authority field will be used to set the HTTP2 :authority pseudo-header. In most cases you will want to override it to be equal to host.

Further background on authority: RFC 3986 also allows host:port, and most servers will accept this too. However, when using TLS, many servers will expect the TLS SNI server name and the :authority pseudo-header to be equal, and for TLS SNI the server name should not include the port. Note that HTTP2 explicitly disallows using userinfo@ as part of the authority.

>>> defaultClientConfig
ClientConfig {scheme = "http", authority = "localhost", cacheLimit = 64, connectionWindowSize = 16777216, settings = Settings {headerTableSize = 4096, enablePush = True, maxConcurrentStreams = Just 64, initialWindowSize = 262144, maxFrameSize = 16384, maxHeaderListSize = Just 65536, pingRateLimit = 10, emptyFrameRateLimit = 4, settingsRateLimit = 4, rstRateLimit = 4}}

https or http

Server name

The maximum number of incoming streams on the net

The window size of connection.

Settings

HTTP/2 settings. See https://datatracker.ietf.org/doc/html/rfc9113#name-defined-settings.

The default settings.

>>> defaultSettings
Settings {headerTableSize = 4096, enablePush = True, maxConcurrentStreams = Just 64, initialWindowSize = 262144, maxFrameSize = 16384, maxHeaderListSize = Just 65536, pingRateLimit = 10, emptyFrameRateLimit = 4, settingsRateLimit = 4, rstRateLimit = 4}

SETTINGS_HEADER_TABLE_SIZE

SETTINGS_ENABLE_PUSH

SETTINGS_MAX_CONCURRENT_STREAMS

SETTINGS_INITIAL_WINDOW_SIZE

SETTINGS_MAX_FRAME_SIZE

SETTINGS_MAX_HEADER_LIST_SIZE. Our own value is also enforced: a field block whose decoded size (RFC 9113 section 6.5.2: the length of each field's name plus its value plus 32) exceeds it resets the stream. With Nothing, nothing is advertised but a limit of 64 KiB is enforced all the same (CVE-2026-49975).

Maximum number of pings allowed per second (CVE-2019-9512)

Maximum number of settings frames allowed per second (CVE-2019-9515)

Maximum number of empty data frames allowed per second (CVE-2019-9518)

Maximum number of streams reset per second, whether by the peer's RST_STREAM (CVE-2023-44487) or by ours in answer to a stream error the peer caused (CVE-2025-8671)

HTTP/2 configuration.

Default config. This is just a template to modify via field names. Don't use this without modifications.

This is used only by frameSender. This MUST be freed after frameSender is terminated.

The size of the write buffer. We assume that the read buffer is the same size. So, this value is announced via SETTINGS_MAX_FRAME_SIZE to the peer.

This is copied into Aux, if exist, on server.

This is copied into Aux, if exist, on server.

Client only: called when a 1xx informational response (e.g. 103 Early Hints) is received on the given stream, ahead of the final response. No-op by default.

Since: 5.4.2

Making simple configuration whose IO is not efficient. A write buffer is allocated internally. WAI timeout manger is initialized with 30_000_000 microseconds.

Making simple configuration whose IO is not efficient. A write buffer is allocated internally. The third argument is microseconds to initialize WAI timeout manager.

allocSimpleConfig' whose receive the caller can give up on. The STM action is waited for beside each receive; when it fires, the reader ends as it does at end of input. Nothing is closed and no thread is interrupted to make it return.

Since: 5.4.11

Deallocating the resource of the simple configuration.

This does not cancel timeout actions registered with confTimeoutManager. Since time-manager 0.3, a manager holds no registrations, so there is nothing to kill: an action registered with register runs even after this returns unless it is cancelled with cancel. Use withHandle, which cancels it when the scope ends.

The connection error or the stream error. A stream error resets that stream and the connection carries on, as RFC 9113 section 5.4.2 asks. One kind of trouble is a connection error even though the spec calls it a stream error, because this implementation cannot carry on through it: a field block abandoned part-way leaves the HPACK tables disagreeing with the peer's, and nothing sent afterwards would decode. ErrorCode in connection errors should be the highest stream identifier but in this implementation it identifies the stream that caused this error.

The type for raw error code.