.\"
.\" Copyright (c) 2000 Alfred Perlstein
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.\" $FreeBSD: src/share/man/man9/accf_data.9,v 1.1.2.4 2001/08/17 13:08:54 ru Exp $
.\" $DragonFly: src/share/man/man9/accf_data.9,v 1.2 2003/06/17 04:37:01 dillon Exp $
.\" "
.Dd November 15, 2000
.Os
.Dt ACCF_DATA 9
.Sh NAME
.Nm accf_data
.Nd buffer incoming connections until data arrives
.Sh SYNOPSIS
.Nm options INET
.Nm options ACCEPT_FILTER_DATA
.Nm kldload accf_data
.Sh DESCRIPTION
This is a filter to be placed on a socket that will be using
.Fn accept
to receive incoming connections.
.Pp
It prevents the application from receiving the connected descriptor via
.Fn accept
until data arrives on the connection.
.Pp
The
.Fa ACCEPT_FILTER_DATA
kernel option is also a module that can be enabled at runtime via
.Xr kldload 8
if the INET option has been compiled into the kernel.
.Sh EXAMPLE
Assuming ACCEPT_FILTER_DATA has been included in the kernel config
file or the module
.Xr accf_data 9
has been loaded, this will enable the data accept filter
on the socket
.Fa sok .
.Bd -literal -offset 0i
	struct accept_filter_arg afa;

	bzero(&afa, sizeof(afa));
	strcpy(afa.af_name, "dataready");
	setsockopt(sok, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));
.Ed
.Sh SEE ALSO
.Xr setsockopt 2 ,
.Xr accept_filter 9 ,
.Xr accf_http 9
.Sh HISTORY
The accept filter mechanism and the
accf_data filter were introduced in
.Fx 4.0 .
.Sh AUTHORS
This manual page and the filter were written by
.An Alfred Perlstein .