The Tcpdump Group git mirrors - tcpdump/blob - print-arp.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 #ifndef lint
  23 static const char rcsid[] =
  24     "@(#) $Header: /tcpdump/master/tcpdump/print-arp.c,v 1.55 2002-08-01 08:53:00 risso Exp $ (LBL)";
  25 #endif
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <tcpdump-stdinc.h>
  32
  33 #include <stdio.h>
  34 #include <string.h>
  35
  36 #include "interface.h"
  37 #include "addrtoname.h"
  38 #include "ether.h"
  39 #include "ethertype.h"
  40 #include "extract.h"                    /* must come after interface.h */
  41
  42 /*
  43  * Address Resolution Protocol.
  44  *
  45  * See RFC 826 for protocol description.  ARP packets are variable
  46  * in size; the arphdr structure defines the fixed-length portion.
  47  * Protocol type values are the same as those for 10 Mb/s Ethernet.
  48  * It is followed by the variable-sized fields ar_sha, arp_spa,
  49  * arp_tha and arp_tpa in that order, according to the lengths
  50  * specified.  Field names used correspond to RFC 826.
  51  */
  52 struct  arp_pkthdr {
  53         u_short ar_hrd;         /* format of hardware address */
  54 #define ARPHRD_ETHER    1       /* ethernet hardware format */
  55 #define ARPHRD_IEEE802  6       /* token-ring hardware format */
  56 #define ARPHRD_ARCNET   7       /* arcnet hardware format */
  57 #define ARPHRD_FRELAY   15      /* frame relay hardware format */
  58 #define ARPHRD_STRIP    23      /* Ricochet Starmode Radio hardware format */
  59 #define ARPHRD_IEEE1394 24      /* IEEE 1394 (FireWire) hardware format */
  60         u_short ar_pro;         /* format of protocol address */
  61         u_char  ar_hln;         /* length of hardware address */
  62         u_char  ar_pln;         /* length of protocol address */
  63         u_short ar_op;          /* one of: */
  64 #define ARPOP_REQUEST   1       /* request to resolve address */
  65 #define ARPOP_REPLY     2       /* response to previous request */
  66 #define ARPOP_REVREQUEST 3      /* request protocol address given hardware */
  67 #define ARPOP_REVREPLY  4       /* response giving protocol address */
  68 #define ARPOP_INVREQUEST 8      /* request to identify peer */
  69 #define ARPOP_INVREPLY  9       /* response identifying peer */
  70 /*
  71  * The remaining fields are variable in size,
  72  * according to the sizes above.
  73  */
  74 #ifdef COMMENT_ONLY
  75         u_char  ar_sha[];       /* sender hardware address */
  76         u_char  ar_spa[];       /* sender protocol address */
  77         u_char  ar_tha[];       /* target hardware address */
  78         u_char  ar_tpa[];       /* target protocol address */
  79 #endif
  80 #define ar_sha(ap)      (((const u_char *)((ap)+1))+0)
  81 #define ar_spa(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln)
  82 #define ar_tha(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln+(ap)->ar_pln)
  83 #define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*(ap)->ar_hln+(ap)->ar_pln)
  84 };
  85
  86 #define ARP_HDRLEN      8
  87
  88 #define HRD(ap) ((ap)->ar_hrd)
  89 #define HLN(ap) ((ap)->ar_hln)
  90 #define PLN(ap) ((ap)->ar_pln)
  91 #define OP(ap)  ((ap)->ar_op)
  92 #define PRO(ap) ((ap)->ar_pro)
  93 #define SHA(ap) (ar_sha(ap))
  94 #define SPA(ap) (ar_spa(ap))
  95 #define THA(ap) (ar_tha(ap))
  96 #define TPA(ap) (ar_tpa(ap))
  97
  98 /*
  99  * ATM Address Resolution Protocol.
 100  *
 101  * See RFC 2225 for protocol description.  ARP packets are variable
 102  * in size; the arphdr structure defines the fixed-length portion.
 103  * Protocol type values are the same as those for 10 Mb/s Ethernet.
 104  * It is followed by the variable-sized fields ar_sha, arp_spa,
 105  * arp_tha and arp_tpa in that order, according to the lengths
 106  * specified.  Field names used correspond to RFC 826.
 107  */
 108 struct  atmarp_pkthdr {
 109         u_short ar_hrd;         /* format of hardware address */
 110 #define ARPHRD_ATM2225  19      /* ATM (RFC 2225) */
 111         u_short ar_pro;         /* format of protocol address */
 112         u_char  ar_shtl;        /* length of hardware address */
 113         u_char  ar_sstl;        /* length of hardware address */
 114         u_short ar_op;          /* same as regular ARP */
 115         u_char  ar_spln;
 116         u_char  ar_thtl;
 117         u_char  ar_tstl;
 118         u_char  ar_tpln;
 119 /*
 120  * The remaining fields are variable in size,
 121  * according to the sizes above.
 122  */
 123 #ifdef COMMENT_ONLY
 124         u_char  ar_sha[];       /* sender hardware address */
 125         u_char  ar_spa[];       /* sender protocol address */
 126         u_char  ar_tha[];       /* target hardware address */
 127         u_char  ar_tpa[];       /* target protocol address */
 128 #endif
 129 #define ar_sha(ap)      (((const u_char *)((ap)+1))+0)
 130 #define ar_spa(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln)
 131 #define ar_tha(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln+(ap)->ar_pln)
 132 #define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*(ap)->ar_hln+(ap)->ar_pln)
 133 };
 134
 135 static u_char ezero[6];
 136
 137 static void
 138 atmarp_print(const u_char *bp, u_int length, u_int caplen)
 139 {
 140         const struct arp_pkthdr *ap;
 141         u_short pro, hrd, op;
 142
 143         ap = (const struct arp_pkthdr *)bp;
 144         TCHECK(*ap);
 145         if ((const u_char *)(ar_tpa(ap) + PLN(ap)) > snapend) {
 146                 (void)printf("truncated-arp");
 147                 default_print((const u_char *)ap, length);
 148                 return;
 149         }
 150
 151         hrd = EXTRACT_16BITS(&HRD(ap));
 152         if (hrd == ARPHRD_ATM2225)
 153                 atmarp_print(bp, length, caplen);
 154         pro = EXTRACT_16BITS(&PRO(ap));
 155         op = EXTRACT_16BITS(&OP(ap));
 156
 157         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) {
 158                 (void)printf("arp-#%d for proto #%d (%d) hardware #%d (%d)",
 159                                 op, pro, PLN(ap), hrd, HLN(ap));
 160                 return;
 161         }
 162         if (pro == ETHERTYPE_TRAIL)
 163                 (void)printf("trailer-");
 164         switch (op) {
 165
 166         case ARPOP_REQUEST:
 167                 (void)printf("arp who-has %s", ipaddr_string(TPA(ap)));
 168                 if (memcmp((const char *)ezero, (const char *)THA(ap), HLN(ap)) != 0)
 169                         (void)printf(" (%s)",
 170                             linkaddr_string(THA(ap), HLN(ap)));
 171                 (void)printf(" tell %s", ipaddr_string(SPA(ap)));
 172                 break;
 173
 174         case ARPOP_REPLY:
 175                 (void)printf("arp reply %s", ipaddr_string(SPA(ap)));
 176                 (void)printf(" is-at %s", linkaddr_string(SHA(ap), HLN(ap)));
 177                 break;
 178
 179         case ARPOP_REVREQUEST:
 180                 (void)printf("rarp who-is %s tell %s",
 181                         linkaddr_string(THA(ap), HLN(ap)),
 182                         linkaddr_string(SHA(ap), HLN(ap)));
 183                 break;
 184
 185         case ARPOP_REVREPLY:
 186                 (void)printf("rarp reply %s at %s",
 187                         linkaddr_string(THA(ap), HLN(ap)),
 188                         ipaddr_string(TPA(ap)));
 189                 break;
 190
 191         case ARPOP_INVREQUEST:
 192                 (void)printf("invarp who-is %s tell %s",
 193                         linkaddr_string(THA(ap), HLN(ap)),
 194                         linkaddr_string(SHA(ap), HLN(ap)));
 195                 break;
 196
 197         case ARPOP_INVREPLY:
 198                 (void)printf("invarp reply %s at %s",
 199                         linkaddr_string(THA(ap), HLN(ap)),
 200                         ipaddr_string(TPA(ap)));
 201                 break;
 202
 203         default:
 204                 (void)printf("arp-#%d", op);
 205                 default_print((const u_char *)ap, caplen);
 206                 return;
 207         }
 208         if (hrd != ARPHRD_ETHER)
 209                 printf(" hardware #%d", hrd);
 210         return;
 211 trunc:
 212         (void)printf("[|arp]");
 213 }
 214
 215 void
 216 arp_print(const u_char *bp, u_int length, u_int caplen)
 217 {
 218         const struct arp_pkthdr *ap;
 219         u_short pro, hrd, op;
 220
 221         ap = (const struct arp_pkthdr *)bp;
 222         TCHECK(*ap);
 223         if ((const u_char *)(ar_tpa(ap) + PLN(ap)) > snapend) {
 224                 (void)printf("truncated-arp");
 225                 default_print((const u_char *)ap, length);
 226                 return;
 227         }
 228
 229         hrd = EXTRACT_16BITS(&HRD(ap));
 230         if (hrd == ARPHRD_ATM2225)
 231                 atmarp_print(bp, length, caplen);
 232         pro = EXTRACT_16BITS(&PRO(ap));
 233         op = EXTRACT_16BITS(&OP(ap));
 234
 235         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) {
 236                 (void)printf("arp-#%d for proto #%d (%d) hardware #%d (%d)",
 237                                 op, pro, PLN(ap), hrd, HLN(ap));
 238                 return;
 239         }
 240         if (pro == ETHERTYPE_TRAIL)
 241                 (void)printf("trailer-");
 242         switch (op) {
 243
 244         case ARPOP_REQUEST:
 245                 (void)printf("arp who-has %s", ipaddr_string(TPA(ap)));
 246                 if (memcmp((const char *)ezero, (const char *)THA(ap), HLN(ap)) != 0)
 247                         (void)printf(" (%s)",
 248                             linkaddr_string(THA(ap), HLN(ap)));
 249                 (void)printf(" tell %s", ipaddr_string(SPA(ap)));
 250                 break;
 251
 252         case ARPOP_REPLY:
 253                 (void)printf("arp reply %s", ipaddr_string(SPA(ap)));
 254                 (void)printf(" is-at %s", linkaddr_string(SHA(ap), HLN(ap)));
 255                 break;
 256
 257         case ARPOP_REVREQUEST:
 258                 (void)printf("rarp who-is %s tell %s",
 259                         linkaddr_string(THA(ap), HLN(ap)),
 260                         linkaddr_string(SHA(ap), HLN(ap)));
 261                 break;
 262
 263         case ARPOP_REVREPLY:
 264                 (void)printf("rarp reply %s at %s",
 265                         linkaddr_string(THA(ap), HLN(ap)),
 266                         ipaddr_string(TPA(ap)));
 267                 break;
 268
 269         case ARPOP_INVREQUEST:
 270                 (void)printf("invarp who-is %s tell %s",
 271                         linkaddr_string(THA(ap), HLN(ap)),
 272                         linkaddr_string(SHA(ap), HLN(ap)));
 273                 break;
 274
 275         case ARPOP_INVREPLY:
 276                 (void)printf("invarp reply %s at %s",
 277                         linkaddr_string(THA(ap), HLN(ap)),
 278                         ipaddr_string(TPA(ap)));
 279                 break;
 280
 281         default:
 282                 (void)printf("arp-#%d", op);
 283                 default_print((const u_char *)ap, caplen);
 284                 return;
 285         }
 286         if (hrd != ARPHRD_ETHER)
 287                 printf(" hardware #%d", hrd);
 288         return;
 289 trunc:
 290         (void)printf("[|arp]");
 291 }