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Add a man page for the DNS accept filter.

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dwmalone 2008-07-18 14:46:01 +00:00
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1
share/man/man9/Makefile
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@ -2,6 +2,7 @@
MAN= accept_filter.9 \
accf_data.9 \
accf_dns.9 \
accf_http.9 \
acl.9 \
alloc_unr.9 \

1
share/man/man9/accept_filter.9
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@ -131,6 +131,7 @@ macro.
.Sh SEE ALSO
.Xr setsockopt 2 ,
.Xr accf_data 9 ,
.Xr accf_dns 9 ,
.Xr accf_http 9 ,
.Xr malloc 9
.Sh HISTORY

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share/man/man9/accf_data.9
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@ -67,6 +67,7 @@ on the socket
.Sh SEE ALSO
.Xr setsockopt 2 ,
.Xr accept_filter 9 ,
.Xr accf_dns 9
.Xr accf_http 9
.Sh HISTORY
The accept filter mechanism and the

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share/man/man9/accf_dns.9 Normal file
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.\"
.\" Copyright (c) 2008 David Malone
.\"
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\" "
.Dd July 16, 2008
.Os
.Dt ACCF_DNS 9
.Sh NAME
.Nm accf_dns
.Nd buffer incoming DNS requests until the whole first request is present
.Sh SYNOPSIS
.Nm options INET
.Nm options ACCEPT_FILTER_DNS
.Nm kldload accf_dns
.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 a whole DNS request is available on the socket.
It does this by reading the first two bytes of the request,
to determine its size,
and waiting until the required amount of data is available to be read.
.Pp
The
.Fa ACCEPT_FILTER_DNS
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 EXAMPLES
If the
.Nm
module is available in the kernel,
the following code will enable the DNS accept filter
on a socket
.Fa sok .
.Bd -literal -offset 0i
struct accept_filter_arg afa;
bzero(&afa, sizeof(afa));
strcpy(afa.af_name, "dnsready");
setsockopt(sok, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));
.Ed
.Sh SEE ALSO
.Xr setsockopt 2 ,
.Xr accept_filter 9 ,
.Xr accf_http 9
.Xr accf_data 9
.Sh HISTORY
The accept filter mechanism was introduced in
.Fx 4.0 .
.Sh AUTHORS
This manual page and the filter were written by
.An David Malone .