Apache Module mod_reqtimeout

Description:	Set timeout and minimum data rate for receiving requests
Status:	Extension
Module Identifier:	reqtimeout_module
Source File:	mod_reqtimeout.c
Compatibility:	Available in IBM HTTP Server 6.1.0.41, 7.0.0.21, 8.0.0.2 and later

Directives

RequestReadTimeout

Topics

Limitations
Examples

Limitations

Under many circumstances, a 408 (HTTP Request Timeout) status code cannot be issued to the client nor logged based on limitations of the Apache HTTP Server API.
Requests often persist for some small amount of time while being gracefully shut down, so there is no expectation that end-to-end request times will be precisely limited by the configured timeouts.
In IBM HTTP Server 6.1, the native environment variable 'IHS_ENABLE_408' is required to properly issue 408 in some scenarios (added in 6.1.0.31).

Examples

Allow 10 seconds to receive the request including the headers and 30 seconds for receiving the request body:
RequestReadTimeout header=10 body=30
Allow at least 10 seconds to receive the request body. If the client sends data, increase the timeout by 1 second for every 1000 bytes received, with no upper limit for the timeout (exept for the limit given indirectly by LimitRequestBody):
RequestReadTimeout body=10,MinRate=1000
Allow at least 10 seconds to receive the request including the headers. If the client sends data, increase the timeout by 1 second for every 500 bytes received. But do not allow more than 30 seconds for the request including the headers:
RequestReadTimeout header=10-30,MinRate=500
Usually, a server should have both header and body timeouts configured. If a common configuration is used for http and https virtual hosts, the timeouts should not be set too low:
RequestReadTimeout header=20-40,MinRate=500 body=20,MinRate=500

RequestReadTimeout Directive

Description:	Set timeout values for receiving request headers and body from client.
Syntax:	`RequestReadTimeout [header=timeout[[-maxtimeout],MinRate=rate] [body=timeout[[-maxtimeout],MinRate=rate]`
Default:	`Unset; no limit`
Context:	server config, virtual host
Status:	Extension
Module:	mod_reqtimeout

This directive can set various timeouts for receiving the request headers and the request body from the client. If the client fails to send headers or body within the configured time, a 408 REQUEST TIME OUT error is sent.

For SSL virtual hosts, the header timeout values include the time needed to do the initial SSL handshake. If the user's browser is configured to query certificate revocation lists and the CRL server is not reachable, the initial SSL handshake may take a significant time until the browser gives up waiting for the CRL. Therefore the header timeout values should not be set to very low values for SSL virtual hosts. The body timeout values include the time needed for SSL renegotiation (if necessary).

When an AcceptFilter is in use (usually the case on Linux and FreeBSD), the socket is not sent to the server process before at least one byte (or the whole request for httpready) is received. The header timeout configured with RequestReadTimeout is only effective after the server process has received the socket.

For each of the two timeout types (header or body), there are three ways to specify the timeout:

Fixed timeout value:

type=timeout

The time in seconds allowed for reading all of the request headers or body, respectively. A value of 0 means no limit.
Timeout value that is increased when data is received:

type=timeout,MinRate=data_rate

Same as above, but whenever data is received, the timeout value is increased according to the specified minimum data rate (in bytes per second).
Timeout value that is increased when data is received, with an upper bound:

type=timeout-maxtimeout,MinRate=data_rate

Same as above, but the timeout will not be increased above the second value of the specified timeout range.