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print-arp.c

/*
 * 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.
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/tcpdump/print-arp.c,v 1.61.2.2 2003/11/16 08:51:10 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.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      arp_pkthdr {
      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_ARCNET   7     /* arcnet hardware format */
#define ARPHRD_FRELAY   15    /* frame relay hardware format */
#define ARPHRD_STRIP    23    /* Ricochet Starmode Radio hardware format */
#define ARPHRD_IEEE1394 24    /* IEEE 1394 (FireWire) 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 ar_sha(ap)      (((const u_char *)((ap)+1))+0)
#define ar_spa(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln)
#define ar_tha(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln+(ap)->ar_pln)
#define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*(ap)->ar_hln+(ap)->ar_pln)
};

#define ARP_HDRLEN      8

#define HRD(ap) EXTRACT_16BITS(&(ap)->ar_hrd)
#define HLN(ap) ((ap)->ar_hln)
#define PLN(ap) ((ap)->ar_pln)
#define OP(ap)  EXTRACT_16BITS(&(ap)->ar_op)
#define PRO(ap) EXTRACT_16BITS(&(ap)->ar_pro)
#define SHA(ap) (ar_sha(ap))
#define SPA(ap) (ar_spa(ap))
#define THA(ap) (ar_tha(ap))
#define TPA(ap) (ar_tpa(ap))

/*
 * ATM Address Resolution Protocol.
 *
 * See RFC 2225 for protocol description.  ATMARP packets are similar
 * to ARP packets, except that there are no length fields for the
 * protocol address - instead, there are type/length fields for
 * the ATM number and subaddress - and the hardware addresses consist
 * of an ATM number and an ATM subaddress.
 */
struct      atmarp_pkthdr {
      u_short     aar_hrd;    /* format of hardware address */
#define ARPHRD_ATM2225  19    /* ATM (RFC 2225) */
      u_short     aar_pro;    /* format of protocol address */
      u_char      aar_shtl;   /* length of source ATM number */
      u_char      aar_sstl;   /* length of source ATM subaddress */
#define ATMARP_IS_E164  0x40  /* bit in type/length for E.164 format */
#define ATMARP_LEN_MASK 0x3F  /* length of {sub}address in type/length */
      u_short     aar_op;           /* same as regular ARP */
#define ATMARPOP_NAK    10    /* NAK */
      u_char      aar_spln;   /* length of source protocol address */
      u_char      aar_thtl;   /* length of target ATM number */
      u_char      aar_tstl;   /* length of target ATM subaddress */
      u_char      aar_tpln;   /* length of target protocol address */
/*
 * The remaining fields are variable in size,
 * according to the sizes above.
 */
#ifdef COMMENT_ONLY
      u_char      aar_sha[];  /* source ATM number */
      u_char      aar_ssa[];  /* source ATM subaddress */
      u_char      aar_spa[];  /* sender protocol address */
      u_char      aar_tha[];  /* target ATM number */
      u_char      aar_tsa[];  /* target ATM subaddress */
      u_char      aar_tpa[];  /* target protocol address */
#endif

#define ATMHRD(ap)  EXTRACT_16BITS(&(ap)->aar_hrd)
#define ATMSHLN(ap) ((ap)->aar_shtl & ATMARP_LEN_MASK)
#define ATMSSLN(ap) ((ap)->aar_sstl & ATMARP_LEN_MASK)
#define ATMSPLN(ap) ((ap)->aar_spln)
#define ATMOP(ap)   EXTRACT_16BITS(&(ap)->aar_op)
#define ATMPRO(ap)  EXTRACT_16BITS(&(ap)->aar_pro)
#define ATMTHLN(ap) ((ap)->aar_thtl & ATMARP_LEN_MASK)
#define ATMTSLN(ap) ((ap)->aar_tstl & ATMARP_LEN_MASK)
#define ATMTPLN(ap) ((ap)->aar_tpln)
#define aar_sha(ap)     ((const u_char *)((ap)+1))
#define aar_ssa(ap)     (aar_sha(ap) + ATMSHLN(ap))
#define aar_spa(ap)     (aar_ssa(ap) + ATMSSLN(ap))
#define aar_tha(ap)     (aar_spa(ap) + ATMSPLN(ap))
#define aar_tsa(ap)     (aar_tha(ap) + ATMTHLN(ap))
#define aar_tpa(ap)     (aar_tsa(ap) + ATMTSLN(ap))
};

#define ATMSHA(ap) (aar_sha(ap))
#define ATMSSA(ap) (aar_ssa(ap))
#define ATMSPA(ap) (aar_spa(ap))
#define ATMTHA(ap) (aar_tha(ap))
#define ATMTSA(ap) (aar_tsa(ap))
#define ATMTPA(ap) (aar_tpa(ap))

static u_char ezero[6];

static void
atmarp_addr_print(const u_char *ha, u_int ha_len, const u_char *srca,
    u_int srca_len)
{
      if (ha_len == 0)
            (void)printf("<No address>");
      else {
            (void)printf("%s", linkaddr_string(ha, ha_len));
            if (srca_len != 0)
                  (void)printf(",%s", linkaddr_string(srca, srca_len));
      }
}

static void
atmarp_print(const u_char *bp, u_int length, u_int caplen)
{
      const struct atmarp_pkthdr *ap;
      u_short pro, hrd, op;

      ap = (const struct atmarp_pkthdr *)bp;
      TCHECK(*ap);

      hrd = ATMHRD(ap);
      pro = ATMPRO(ap);
      op = ATMOP(ap);

      if (!TTEST2(*aar_tpa(ap), ATMTPLN(ap))) {
            (void)printf("truncated-atmarp");
            default_print((const u_char *)ap, length);
            return;
      }

      if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
          ATMSPLN(ap) != 4 || ATMTPLN(ap) != 4) {
            (void)printf("atmarp-#%d for proto #%d (%d/%d) hardware #%d",
                        op, pro, ATMSPLN(ap), ATMTPLN(ap), hrd);
            return;
      }
      if (pro == ETHERTYPE_TRAIL)
            (void)printf("trailer-");
      switch (op) {

      case ARPOP_REQUEST:
            (void)printf("arp who-has %s", ipaddr_string(ATMTPA(ap)));
            if (ATMTHLN(ap) != 0) {
                  (void)printf(" (");
                  atmarp_addr_print(ATMTHA(ap), ATMTHLN(ap),
                      ATMTSA(ap), ATMTSLN(ap));
                  (void)printf(")");
            }
            (void)printf(" tell %s", ipaddr_string(ATMSPA(ap)));
            break;

      case ARPOP_REPLY:
            (void)printf("arp reply %s", ipaddr_string(ATMSPA(ap)));
            (void)printf(" is-at ");
            atmarp_addr_print(ATMSHA(ap), ATMSHLN(ap), ATMSSA(ap),
                ATMSSLN(ap));
            break;

      case ARPOP_INVREQUEST:
            (void)printf("invarp who-is ");
            atmarp_addr_print(ATMTHA(ap), ATMTHLN(ap), ATMTSA(ap),
                ATMTSLN(ap));
            (void)printf(" tell ");
            atmarp_addr_print(ATMSHA(ap), ATMSHLN(ap), ATMSSA(ap),
                ATMSSLN(ap));
            break;

      case ARPOP_INVREPLY:
            (void)printf("invarp reply ");
            atmarp_addr_print(ATMSHA(ap), ATMSHLN(ap), ATMSSA(ap),
                ATMSSLN(ap));
            (void)printf(" at %s", ipaddr_string(ATMSPA(ap)));
            break;

      case ATMARPOP_NAK:
            (void)printf("nak reply for %s",
                  ipaddr_string(ATMSPA(ap)));
            break;

      default:
            (void)printf("atmarp-#%d", op);
            default_print((const u_char *)ap, caplen);
            return;
      }
      return;
trunc:
      (void)printf("[|atmarp]");
}

void
arp_print(const u_char *bp, u_int length, u_int caplen)
{
      const struct arp_pkthdr *ap;
      u_short pro, hrd, op;

      ap = (const struct arp_pkthdr *)bp;
      TCHECK(*ap);
      hrd = HRD(ap);
      if (hrd == ARPHRD_ATM2225) {
            atmarp_print(bp, length, caplen);
            return;
      }
      pro = PRO(ap);
      op = OP(ap);

      if (!TTEST2(*ar_tpa(ap), PLN(ap))) {
            (void)printf("truncated-arp");
            default_print((const u_char *)ap, length);
            return;
      }

      if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
          PLN(ap) != 4 || HLN(ap) == 0) {
            (void)printf("arp-#%d for proto #%d (%d) hardware #%d (%d)",
                        op, pro, PLN(ap), hrd, HLN(ap));
            return;
      }
      if (pro == ETHERTYPE_TRAIL)
            (void)printf("trailer-");
      switch (op) {

      case ARPOP_REQUEST:
            (void)printf("arp who-has %s", ipaddr_string(TPA(ap)));
            if (memcmp((const char *)ezero, (const char *)THA(ap), HLN(ap)) != 0)
                  (void)printf(" (%s)",
                      linkaddr_string(THA(ap), HLN(ap)));
            (void)printf(" tell %s", ipaddr_string(SPA(ap)));
            break;

      case ARPOP_REPLY:
            (void)printf("arp reply %s", ipaddr_string(SPA(ap)));
            (void)printf(" is-at %s", linkaddr_string(SHA(ap), HLN(ap)));
            break;

      case ARPOP_REVREQUEST:
            (void)printf("rarp who-is %s tell %s",
                  linkaddr_string(THA(ap), HLN(ap)),
                  linkaddr_string(SHA(ap), HLN(ap)));
            break;

      case ARPOP_REVREPLY:
            (void)printf("rarp reply %s at %s",
                  linkaddr_string(THA(ap), HLN(ap)),
                  ipaddr_string(TPA(ap)));
            break;

      case ARPOP_INVREQUEST:
            (void)printf("invarp who-is %s tell %s",
                  linkaddr_string(THA(ap), HLN(ap)),
                  linkaddr_string(SHA(ap), HLN(ap)));
            break;

      case ARPOP_INVREPLY:
            (void)printf("invarp reply %s at %s",
                  linkaddr_string(THA(ap), HLN(ap)),
                  ipaddr_string(TPA(ap)));
            break;

      default:
            (void)printf("arp-#%d", op);
            default_print((const u_char *)ap, caplen);
            return;
      }
      if (hrd != ARPHRD_ETHER)
            printf(" hardware #%d", hrd);
      return;
trunc:
      (void)printf("[|arp]");
}

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