100 lines
3.6 KiB
Groff
100 lines
3.6 KiB
Groff
.\" $NetBSD: pfil.9,v 1.3 1996/12/02 01:00:50 tls Exp $
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.\"
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.\" Copyright (c) 1996 Matthew R. Green.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Matthew R. Green for
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.\" the NetBSD Project.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd August 4, 1996
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.Dt PFIL 9
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.Os NetBSD
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.Sh NAME
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.Nm pfil
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.Nd packet filter interface
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.Sh SYNOPSIS
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.Fd #include <sys/param.h>
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.Fd #include <netinet/ip.h>
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.Ft struct packet_filter_hook *
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.Fn pfil_hook_get int
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.Ft void
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.Fn pfil_add_hook "int (*func)()" "int flags"
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.Ft void
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.Fn pfil_remove_hook "int (*func)()" "int flags"
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.\"(void *, int, struct ifnet *, int, struct mbuf **)
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.Sh DESCRIPTION
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The
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.Fn pfil
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interface allows a function to be called on every incoming, outgoing or
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bad packet. The hooks for these are embedded in the ip_input and ip_output
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routines. The
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.Fn pfil_hook_get
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function returns the first member of a particular hook, either the in, out
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or bad list. The
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.Fn pfil_add_hook
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function takes a function of the form below as it's first argument, and the
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flags for which lists to add the function to. The possible values for these
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flags are some combination of PFIL_IN, PFIL_OUT and PFIL_BAD. The
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.Fn pfil_remove_hook
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removes a hook from the specified lists.
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.Pp
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The
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.Va func
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argument is a function with the following prototype.
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.Pp
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.Fn func "void *data" "int hlen" "struct ifnet *net" "int dir" "struct mbuf **m"
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.Pp
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The
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.Va data
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describes the packet. Currently, this may only be a pointer to a ip structure. The
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.Va net
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and
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.Va m
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arguments describe the network interface and the mbuf holding data for this
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packet. The
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.Va dir
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is the direction; 0 for incoming packets and 1 for outgoing packets.
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.Pp
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The
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.Fn pfil
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interface is enabled in the kernel via the
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.Sy PFIL_HOOKS
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option.
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.Sh RETURN VALUES
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If successful
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.Fn pfil_hook_get
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returns the first member of the packet filter list,
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.Fn pfil_add_hook
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and
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.Fn pfil_remove_hook
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are expected to always succeed.
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.Sh HISTORY
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The pfil interface first appeared in NetBSD 1.2A.
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.Sh SEE ALSO
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.Xr bpf 4
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