145 lines
4.6 KiB
Groff
145 lines
4.6 KiB
Groff
.\" $NetBSD: arp.9,v 1.22 2004/10/04 19:12:52 rumble Exp $
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.\"
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.\" Copyright (c) 1997 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Ignatios Souvatzis.
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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 the NetBSD
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.\" Foundation, Inc. and its contributors.
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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 FOUNDATION OR CONTRIBUTORS
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.\" BE 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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.\"
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.Dd March 3, 1997
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.Dt ARP 9
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.Os
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.Sh NAME
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.Nm arp ,
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.Nm arp_ifinit ,
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.Nm arpresolve ,
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.Nm arpintr
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.Nd externally visible ARP functions
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.Sh SYNOPSIS
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.In netinet/if_inarp.h
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.Ft void
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.Fn arp_ifinit "struct ifnet *ifp" "struct ifaddr *ifa"
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.Ft int
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.Fn arpresolve "struct ifnet *ifp" "struct rtentry *rt" "struct mbuf *m" "struct sockaddr *dst" "u_char *desten"
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.Ft void
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.Fn arpintr
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.Sh DESCRIPTION
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The
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.Nm
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functions provide the interface between the
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.Nm
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module and the network drivers which need
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.Nm
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functionality.
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Such drivers must request the
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.Ar arp
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attribute in their "files" declaration.
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.Bl -tag -width "arp_ifinit()"
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.It Fn arp_ifinit
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Sets up the
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.Nm
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specific fields in
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.Fa ifa .
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Additionally, it sends out a gratuitous
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.Nm
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request on
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.Fa ifp ,
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so that other machines are warned that we have a (new) address and
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duplicate addresses can be detected.
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.Pp
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You must call this in your drivers' ioctl function when you get a
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SIOCSIFADDR request with an AF_INET address family.
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.It Fn arpresolve
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is called by network output functions to resolve an IPv4 address.
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If no
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.Fa rt
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is given, a new one is looked up or created.
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If the passed or found
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.Fa rt
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does not contain a valid gateway link level address, a pointer to the packet
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in
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.Fa m
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is stored in the route entry, possibly replacing older stored packets, and an
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.Nm
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request is sent instead.
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When an
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.Nm
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reply is received, the last held packet is send.
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Otherwise, the looked up address is returned and written into the storage
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.Fa desten
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points to.
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.Fn arpresolve
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returns 1, if a valid address was stored to
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.Fa desten ,
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and the packet can be sent immediately.
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Else a 0 is returned.
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.It Fn arpintr
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When an
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.Nm
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packet is received, the network driver (class) input interrupt handler queues
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the packet on the arpintrq queue, and requests an
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.Fn arpintr
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soft interrupt callback.
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.Fn arpintr
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dequeues the packets, performs sanity checks and calls (for IPv4
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.Nm
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packets, which are the only ones supported currently) the
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.Fn in_arpinput
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function.
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.Fn in_arpinput
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either generates a reply to request packets, and adds the sender address
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translation to the routing table, if a matching route entry is found.
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If the route entry contained a pointer to a held packet, that packet is
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sent.
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.El
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.Sh SEE ALSO
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.Xr ether_ifattach 9
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.\" .Xr fddi_ifattach 9 ,
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.\" .Xr arc_ifattach 9
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.br
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Plummer, D., "RFC826", An Ethernet Address Resolution Protocol.
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.Sh AUTHORS
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UCB CSRG (original implementation)
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.br
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Ignatios Souvatzis (support for non-Ethernet)
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.Sh CODE REFERENCES
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The ARP code is implemented in
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.Pa sys/net/if_arp.h ,
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.Pa sys/netinet/if_inarp.h
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and
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.Pa sys/netinet/if_arp.c .
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.Sh STANDARDS
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RFC 826
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.Sh HISTORY
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Rewritten to support other than Ethernet link level addresses in
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.Nx 1.3 .
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