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/*
* Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* $FreeBSD$
*/
#ifndef lint
static const char rcsid[] =
"@(#) $Header: /tcpdump/master/tcpdump/print-arp.c,v 1.49 2000/10/10 05:05:07 guy Exp $ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/param.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include "interface.h"
#include "addrtoname.h"
#include "ether.h"
#include "ethertype.h"
#include "extract.h" /* must come after interface.h */
/*
* Address Resolution Protocol.
*
* See RFC 826 for protocol description. ARP packets are variable
* in size; the arphdr structure defines the fixed-length portion.
* Protocol type values are the same as those for 10 Mb/s Ethernet.
* It is followed by the variable-sized fields ar_sha, arp_spa,
* arp_tha and arp_tpa in that order, according to the lengths
* specified. Field names used correspond to RFC 826.
*/
struct arphdr {
u_short ar_hrd; /* format of hardware address */
#define ARPHRD_ETHER 1 /* ethernet hardware format */
#define ARPHRD_IEEE802 6 /* token-ring hardware format */
#define ARPHRD_FRELAY 15 /* frame relay hardware format */
u_short ar_pro; /* format of protocol address */
u_char ar_hln; /* length of hardware address */
u_char ar_pln; /* length of protocol address */
u_short ar_op; /* one of: */
#define ARPOP_REQUEST 1 /* request to resolve address */
#define ARPOP_REPLY 2 /* response to previous request */
#define ARPOP_REVREQUEST 3 /* request protocol address given hardware */
#define ARPOP_REVREPLY 4 /* response giving protocol address */
#define ARPOP_INVREQUEST 8 /* request to identify peer */
#define ARPOP_INVREPLY 9 /* response identifying peer */
/*
* The remaining fields are variable in size,
* according to the sizes above.
*/
#ifdef COMMENT_ONLY
u_char ar_sha[]; /* sender hardware address */
u_char ar_spa[]; /* sender protocol address */
u_char ar_tha[]; /* target hardware address */
u_char ar_tpa[]; /* target protocol address */
#endif
};
#define ARP_HDRLEN 8
/*
* Ethernet Address Resolution Protocol.
*
* See RFC 826 for protocol description. Structure below is adapted
* to resolving internet addresses. Field names used correspond to
* RFC 826.
*/
struct ether_arp {
struct arphdr ea_hdr; /* fixed-size header */
u_char arp_sha[6]; /* sender hardware address */
u_char arp_spa[4]; /* sender protocol address */
u_char arp_tha[6]; /* target hardware address */
u_char arp_tpa[4]; /* target protocol address */
};
#define arp_hrd ea_hdr.ar_hrd
#define arp_pro ea_hdr.ar_pro
#define arp_hln ea_hdr.ar_hln
#define arp_pln ea_hdr.ar_pln
#define arp_op ea_hdr.ar_op
#define ETHER_ARP_HDRLEN (ARP_HDRLEN + 6 + 4 + 6 + 4)
#define SHA(ap) ((ap)->arp_sha)
#define THA(ap) ((ap)->arp_tha)
#define SPA(ap) ((ap)->arp_spa)
#define TPA(ap) ((ap)->arp_tpa)
/* Compatibility */
#ifndef REVARP_REQUEST
#define REVARP_REQUEST 3
#endif
#ifndef REVARP_REPLY
#define REVARP_REPLY 4
#endif
static u_char ezero[6];
void
arp_print(register const u_char *bp, u_int length, u_int caplen)
{
register const struct ether_arp *ap;
register const struct ether_header *eh;
register u_short pro, hrd, op;
ap = (struct ether_arp *)bp;
if ((u_char *)(ap + 1) > snapend) {
printf("[|arp]");
return;
}
if (length < ETHER_ARP_HDRLEN) {
(void)printf("truncated-arp");
default_print((u_char *)ap, length);
return;
}
pro = EXTRACT_16BITS(&ap->arp_pro);
hrd = EXTRACT_16BITS(&ap->arp_hrd);
op = EXTRACT_16BITS(&ap->arp_op);
if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
|| ap->arp_hln != sizeof(SHA(ap))
|| ap->arp_pln != sizeof(SPA(ap))) {
(void)printf("arp-#%d for proto #%d (%d) hardware #%d (%d)",
op, pro, ap->arp_pln,
hrd, ap->arp_hln);
return;
}
if (pro == ETHERTYPE_TRAIL)
(void)printf("trailer-");
eh = (struct ether_header *)packetp;
switch (op) {
case ARPOP_REQUEST:
(void)printf("arp who-has %s", ipaddr_string(TPA(ap)));
if (memcmp((char *)ezero, (char *)THA(ap), 6) != 0)
(void)printf(" (%s)", etheraddr_string(THA(ap)));
(void)printf(" tell %s", ipaddr_string(SPA(ap)));
if (memcmp((char *)ESRC(eh), (char *)SHA(ap), 6) != 0)
(void)printf(" (%s)", etheraddr_string(SHA(ap)));
break;
case ARPOP_REPLY:
(void)printf("arp reply %s", ipaddr_string(SPA(ap)));
if (memcmp((char *)ESRC(eh), (char *)SHA(ap), 6) != 0)
(void)printf(" (%s)", etheraddr_string(SHA(ap)));
(void)printf(" is-at %s", etheraddr_string(SHA(ap)));
if (memcmp((char *)EDST(eh), (char *)THA(ap), 6) != 0)
(void)printf(" (%s)", etheraddr_string(THA(ap)));
break;
case REVARP_REQUEST:
(void)printf("rarp who-is %s tell %s",
etheraddr_string(THA(ap)),
etheraddr_string(SHA(ap)));
break;
case REVARP_REPLY:
(void)printf("rarp reply %s at %s",
etheraddr_string(THA(ap)),
ipaddr_string(TPA(ap)));
break;
default:
(void)printf("arp-#%d", op);
default_print((u_char *)ap, caplen);
return;
}
if (hrd != ARPHRD_ETHER)
printf(" hardware #%d", hrd);
}
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