.\" $NetBSD: accf_data.9,v 1.6 2017/07/03 21:28:48 wiz Exp $
.\"
.\" Copyright (c) 2000 Alfred Perlstein
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.\" $FreeBSD: src/share/man/man9/accf_data.9,v 1.8 2005/01/18 20:52:51 ru Exp $
.\" "
.Dd August 10, 2008
.Dt ACCF_DATA 9
.Os
.Sh NAME
.Nm accf_data
.Nd buffer incoming connections until data arrives
.Sh SYNOPSIS
.Cd "options INET"
.Cd "pseudo-device 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.
.Sh EXAMPLES
If the
.Nm
accept filter is present in the kernel configuration,
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
.Nm
filter were introduced in
.Fx 4.0 .
They were ported to
.Nx
by Coyote Point Systems and appeared in
.Nx 5.0 .
.Sh AUTHORS
This manual page and the filter were written by
.An Alfred Perlstein .