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ACCF_HTTP(9)	       FreeBSD Kernel Developer's Manual	  ACCF_HTTP(9)

NAME
     accf_http -- buffer incoming connections until a certain complete HTTP
     requests arrive

SYNOPSIS
     options INET
     options ACCEPT_FILTER_HTTP
     kldload accf_http

DESCRIPTION
     This is a filter to be placed on a	socket that will be using accept() to
     receive incoming HTTP connections.

     It	prevents the application from receiving	the connected descriptor via
     accept() until either a full HTTP/1.0 or HTTP/1.1 HEAD or GET request has
     been buffered by the kernel.

     If	something other	than a HTTP/1.0	or HTTP/1.1 HEAD or GET	request	is
     received the kernel will allow the	application to receive the connection
     descriptor	via accept().

     The utility of accf_http is such that a server will not have to context
     switch several times before performing the	initial	parsing	of the
     request.  This effectively	reduces	the amount of required CPU utilization
     to	handle incoming	requests by keeping active processes in	preforking
     servers such as Apache low	and reducing the size of the file descriptor
     set that needs to be managed by interfaces	such as	select(), poll() or
     kevent() based servers.

     The accf_http kernel option is also a module that can be enabled at run-
     time via kldload(8) if the	INET option has	been compiled into the kernel.

EXAMPLES
     Assuming ACCEPT_FILTER_HTTP has been included in the kernel config	file
     or	the accf_http module has been loaded, this will	enable the http	accept
     filter on the socket sok.

	     struct accept_filter_arg afa;

	     bzero(&afa, sizeof(afa));
	     strcpy(afa.af_name, "httpready");
	     setsockopt(sok, SOL_SOCKET, SO_ACCEPTFILTER, &afa,	sizeof(afa));

SEE ALSO
     setsockopt(2), accept_filter(9)

HISTORY
     The accept	filter mechanism and the accf_http filter were introduced in
     FreeBSD 4.0.

AUTHORS
     This manual page and the filter were written by Alfred Perlstein.

FreeBSD	9.2		       November	15, 2000		   FreeBSD 9.2

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | HISTORY | AUTHORS

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