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 /* \summary: Address Resolution Protocol (ARP) printer */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include "config.h"
  26 #endif
  27
  28 #include <netdissect-stdinc.h>
  29
  30 #include <string.h>
  31
  32 #include "netdissect.h"
  33 #include "addrtoname.h"
  34 #include "ether.h"
  35 #include "ethertype.h"
  36 #include "extract.h"
  37
  38 static const char tstr[] = "[|ARP]";
  39
  40 /*
  41  * Address Resolution Protocol.
  42  *
  43  * See RFC 826 for protocol description.  ARP packets are variable
  44  * in size; the arphdr structure defines the fixed-length portion.
  45  * Protocol type values are the same as those for 10 Mb/s Ethernet.
  46  * It is followed by the variable-sized fields ar_sha, arp_spa,
  47  * arp_tha and arp_tpa in that order, according to the lengths
  48  * specified.  Field names used correspond to RFC 826.
  49  */
  50 struct  arp_pkthdr {
  51         u_short ar_hrd;         /* format of hardware address */
  52 #define ARPHRD_ETHER    1       /* ethernet hardware format */
  53 #define ARPHRD_IEEE802  6       /* token-ring hardware format */
  54 #define ARPHRD_ARCNET   7       /* arcnet hardware format */
  55 #define ARPHRD_FRELAY   15      /* frame relay hardware format */
  56 #define ARPHRD_ATM2225  19      /* ATM (RFC 2225) */
  57 #define ARPHRD_STRIP    23      /* Ricochet Starmode Radio hardware format */
  58 #define ARPHRD_IEEE1394 24      /* IEEE 1394 (FireWire) hardware format */
  59         u_short ar_pro;         /* format of protocol address */
  60         u_char  ar_hln;         /* length of hardware address */
  61         u_char  ar_pln;         /* length of protocol address */
  62         u_short ar_op;          /* one of: */
  63 #define ARPOP_REQUEST   1       /* request to resolve address */
  64 #define ARPOP_REPLY     2       /* response to previous request */
  65 #define ARPOP_REVREQUEST 3      /* request protocol address given hardware */
  66 #define ARPOP_REVREPLY  4       /* response giving protocol address */
  67 #define ARPOP_INVREQUEST 8      /* request to identify peer */
  68 #define ARPOP_INVREPLY  9       /* response identifying peer */
  69 #define ARPOP_NAK       10      /* NAK - only valif for ATM ARP */
  70
  71 /*
  72  * The remaining fields are variable in size,
  73  * according to the sizes above.
  74  */
  75 #ifdef COMMENT_ONLY
  76         u_char  ar_sha[];       /* sender hardware address */
  77         u_char  ar_spa[];       /* sender protocol address */
  78         u_char  ar_tha[];       /* target hardware address */
  79         u_char  ar_tpa[];       /* target protocol address */
  80 #endif
  81 #define ar_sha(ap)      (((const u_char *)((ap)+1))+  0)
  82 #define ar_spa(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln)
  83 #define ar_tha(ap)      (((const u_char *)((ap)+1))+  (ap)->ar_hln+(ap)->ar_pln)
  84 #define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*(ap)->ar_hln+(ap)->ar_pln)
  85 };
  86
  87 #define ARP_HDRLEN      8
  88
  89 #define HRD(ap) EXTRACT_BE_U_2(&(ap)->ar_hrd)
  90 #define HRD_LEN(ap) ((ap)->ar_hln)
  91 #define PROTO_LEN(ap) ((ap)->ar_pln)
  92 #define OP(ap)  EXTRACT_BE_U_2(&(ap)->ar_op)
  93 #define PRO(ap) EXTRACT_BE_U_2(&(ap)->ar_pro)
  94 #define SHA(ap) (ar_sha(ap))
  95 #define SPA(ap) (ar_spa(ap))
  96 #define THA(ap) (ar_tha(ap))
  97 #define TPA(ap) (ar_tpa(ap))
  98
  99
 100 static const struct tok arpop_values[] = {
 101     { ARPOP_REQUEST, "Request" },
 102     { ARPOP_REPLY, "Reply" },
 103     { ARPOP_REVREQUEST, "Reverse Request" },
 104     { ARPOP_REVREPLY, "Reverse Reply" },
 105     { ARPOP_INVREQUEST, "Inverse Request" },
 106     { ARPOP_INVREPLY, "Inverse Reply" },
 107     { ARPOP_NAK, "NACK Reply" },
 108     { 0, NULL }
 109 };
 110
 111 static const struct tok arphrd_values[] = {
 112     { ARPHRD_ETHER, "Ethernet" },
 113     { ARPHRD_IEEE802, "TokenRing" },
 114     { ARPHRD_ARCNET, "ArcNet" },
 115     { ARPHRD_FRELAY, "FrameRelay" },
 116     { ARPHRD_STRIP, "Strip" },
 117     { ARPHRD_IEEE1394, "IEEE 1394" },
 118     { ARPHRD_ATM2225, "ATM" },
 119     { 0, NULL }
 120 };
 121
 122 /*
 123  * ATM Address Resolution Protocol.
 124  *
 125  * See RFC 2225 for protocol description.  ATMARP packets are similar
 126  * to ARP packets, except that there are no length fields for the
 127  * protocol address - instead, there are type/length fields for
 128  * the ATM number and subaddress - and the hardware addresses consist
 129  * of an ATM number and an ATM subaddress.
 130  */
 131 struct  atmarp_pkthdr {
 132         u_short aar_hrd;        /* format of hardware address */
 133         u_short aar_pro;        /* format of protocol address */
 134         u_char  aar_shtl;       /* length of source ATM number */
 135         u_char  aar_sstl;       /* length of source ATM subaddress */
 136 #define ATMARP_IS_E164  0x40    /* bit in type/length for E.164 format */
 137 #define ATMARP_LEN_MASK 0x3F    /* length of {sub}address in type/length */
 138         u_short aar_op;         /* same as regular ARP */
 139         u_char  aar_spln;       /* length of source protocol address */
 140         u_char  aar_thtl;       /* length of target ATM number */
 141         u_char  aar_tstl;       /* length of target ATM subaddress */
 142         u_char  aar_tpln;       /* length of target protocol address */
 143 /*
 144  * The remaining fields are variable in size,
 145  * according to the sizes above.
 146  */
 147 #ifdef COMMENT_ONLY
 148         u_char  aar_sha[];      /* source ATM number */
 149         u_char  aar_ssa[];      /* source ATM subaddress */
 150         u_char  aar_spa[];      /* sender protocol address */
 151         u_char  aar_tha[];      /* target ATM number */
 152         u_char  aar_tsa[];      /* target ATM subaddress */
 153         u_char  aar_tpa[];      /* target protocol address */
 154 #endif
 155
 156 #define ATMHRD(ap)  EXTRACT_BE_U_2(&(ap)->aar_hrd)
 157 #define ATMSHRD_LEN(ap) ((ap)->aar_shtl & ATMARP_LEN_MASK)
 158 #define ATMSSLN(ap) ((ap)->aar_sstl & ATMARP_LEN_MASK)
 159 #define ATMSPROTO_LEN(ap) ((ap)->aar_spln)
 160 #define ATMOP(ap)   EXTRACT_BE_U_2(&(ap)->aar_op)
 161 #define ATMPRO(ap)  EXTRACT_BE_U_2(&(ap)->aar_pro)
 162 #define ATMTHRD_LEN(ap) ((ap)->aar_thtl & ATMARP_LEN_MASK)
 163 #define ATMTSLN(ap) ((ap)->aar_tstl & ATMARP_LEN_MASK)
 164 #define ATMTPROTO_LEN(ap) ((ap)->aar_tpln)
 165 #define aar_sha(ap)     ((const u_char *)((ap)+1))
 166 #define aar_ssa(ap)     (aar_sha(ap) + ATMSHRD_LEN(ap))
 167 #define aar_spa(ap)     (aar_ssa(ap) + ATMSSLN(ap))
 168 #define aar_tha(ap)     (aar_spa(ap) + ATMSPROTO_LEN(ap))
 169 #define aar_tsa(ap)     (aar_tha(ap) + ATMTHRD_LEN(ap))
 170 #define aar_tpa(ap)     (aar_tsa(ap) + ATMTSLN(ap))
 171 };
 172
 173 #define ATMSHA(ap) (aar_sha(ap))
 174 #define ATMSSA(ap) (aar_ssa(ap))
 175 #define ATMSPA(ap) (aar_spa(ap))
 176 #define ATMTHA(ap) (aar_tha(ap))
 177 #define ATMTSA(ap) (aar_tsa(ap))
 178 #define ATMTPA(ap) (aar_tpa(ap))
 179
 180 static int
 181 isnonzero(const u_char *a, size_t len)
 182 {
 183         while (len > 0) {
 184                 if (*a != 0)
 185                         return (1);
 186                 a++;
 187                 len--;
 188         }
 189         return (0);
 190 }
 191
 192 static void
 193 tpaddr_print_ip(netdissect_options *ndo,
 194                 const struct arp_pkthdr *ap, u_short pro)
 195 {
 196         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 197                 ND_PRINT((ndo, "<wrong proto type>"));
 198         else if (PROTO_LEN(ap) != 4)
 199                 ND_PRINT((ndo, "<wrong len>"));
 200         else
 201                 ND_PRINT((ndo, "%s", ipaddr_string(ndo, TPA(ap))));
 202 }
 203
 204 static void
 205 spaddr_print_ip(netdissect_options *ndo,
 206                 const struct arp_pkthdr *ap, u_short pro)
 207 {
 208         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 209                 ND_PRINT((ndo, "<wrong proto type>"));
 210         else if (PROTO_LEN(ap) != 4)
 211                 ND_PRINT((ndo, "<wrong len>"));
 212         else
 213                 ND_PRINT((ndo, "%s", ipaddr_string(ndo, SPA(ap))));
 214 }
 215
 216 static void
 217 atmarp_addr_print(netdissect_options *ndo,
 218                   const u_char *ha, u_int ha_len, const u_char *srca,
 219     u_int srca_len)
 220 {
 221         if (ha_len == 0)
 222                 ND_PRINT((ndo, "<No address>"));
 223         else {
 224                 ND_PRINT((ndo, "%s", linkaddr_string(ndo, ha, LINKADDR_ATM, ha_len)));
 225                 if (srca_len != 0)
 226                         ND_PRINT((ndo, ",%s",
 227                                   linkaddr_string(ndo, srca, LINKADDR_ATM, srca_len)));
 228         }
 229 }
 230
 231 static void
 232 atmarp_tpaddr_print(netdissect_options *ndo,
 233                     const struct atmarp_pkthdr *ap, u_short pro)
 234 {
 235         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 236                 ND_PRINT((ndo, "<wrong proto type>"));
 237         else if (ATMTPROTO_LEN(ap) != 4)
 238                 ND_PRINT((ndo, "<wrong tplen>"));
 239         else
 240                 ND_PRINT((ndo, "%s", ipaddr_string(ndo, ATMTPA(ap))));
 241 }
 242
 243 static void
 244 atmarp_spaddr_print(netdissect_options *ndo,
 245                     const struct atmarp_pkthdr *ap, u_short pro)
 246 {
 247         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 248                 ND_PRINT((ndo, "<wrong proto type>"));
 249         else if (ATMSPROTO_LEN(ap) != 4)
 250                 ND_PRINT((ndo, "<wrong splen>"));
 251         else
 252                 ND_PRINT((ndo, "%s", ipaddr_string(ndo, ATMSPA(ap))));
 253 }
 254
 255 static void
 256 atmarp_print(netdissect_options *ndo,
 257              const u_char *bp, u_int length, u_int caplen)
 258 {
 259         const struct atmarp_pkthdr *ap;
 260         u_short pro, hrd, op;
 261
 262         ap = (const struct atmarp_pkthdr *)bp;
 263         ND_TCHECK(*ap);
 264
 265         hrd = ATMHRD(ap);
 266         pro = ATMPRO(ap);
 267         op = ATMOP(ap);
 268
 269         if (!ND_TTEST2(*aar_tpa(ap), ATMTPROTO_LEN(ap))) {
 270                 ND_PRINT((ndo, "%s", tstr));
 271                 ND_DEFAULTPRINT((const u_char *)ap, length);
 272                 return;
 273         }
 274
 275         if (!ndo->ndo_eflag) {
 276             ND_PRINT((ndo, "ARP, "));
 277         }
 278
 279         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 280             ATMSPROTO_LEN(ap) != 4 ||
 281             ATMTPROTO_LEN(ap) != 4 ||
 282             ndo->ndo_vflag) {
 283                 ND_PRINT((ndo, "%s, %s (len %u/%u)",
 284                           tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 285                           tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 286                           ATMSPROTO_LEN(ap),
 287                           ATMTPROTO_LEN(ap)));
 288
 289                 /* don't know know about the address formats */
 290                 if (!ndo->ndo_vflag) {
 291                     goto out;
 292                 }
 293         }
 294
 295         /* print operation */
 296         ND_PRINT((ndo, "%s%s ",
 297                ndo->ndo_vflag ? ", " : "",
 298                tok2str(arpop_values, "Unknown (%u)", op)));
 299
 300         switch (op) {
 301
 302         case ARPOP_REQUEST:
 303                 ND_PRINT((ndo, "who-has "));
 304                 atmarp_tpaddr_print(ndo, ap, pro);
 305                 if (ATMTHRD_LEN(ap) != 0) {
 306                         ND_PRINT((ndo, " ("));
 307                         atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
 308                             ATMTSA(ap), ATMTSLN(ap));
 309                         ND_PRINT((ndo, ")"));
 310                 }
 311                 ND_PRINT((ndo, " tell "));
 312                 atmarp_spaddr_print(ndo, ap, pro);
 313                 break;
 314
 315         case ARPOP_REPLY:
 316                 atmarp_spaddr_print(ndo, ap, pro);
 317                 ND_PRINT((ndo, " is-at "));
 318                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 319                                   ATMSSLN(ap));
 320                 break;
 321
 322         case ARPOP_INVREQUEST:
 323                 ND_PRINT((ndo, "who-is "));
 324                 atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
 325                     ATMTSLN(ap));
 326                 ND_PRINT((ndo, " tell "));
 327                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 328                     ATMSSLN(ap));
 329                 break;
 330
 331         case ARPOP_INVREPLY:
 332                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 333                     ATMSSLN(ap));
 334                 ND_PRINT((ndo, "at "));
 335                 atmarp_spaddr_print(ndo, ap, pro);
 336                 break;
 337
 338         case ARPOP_NAK:
 339                 ND_PRINT((ndo, "for "));
 340                 atmarp_spaddr_print(ndo, ap, pro);
 341                 break;
 342
 343         default:
 344                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 345                 return;
 346         }
 347
 348  out:
 349         ND_PRINT((ndo, ", length %u", length));
 350         return;
 351
 352 trunc:
 353         ND_PRINT((ndo, "%s", tstr));
 354 }
 355
 356 void
 357 arp_print(netdissect_options *ndo,
 358           const u_char *bp, u_int length, u_int caplen)
 359 {
 360         const struct arp_pkthdr *ap;
 361         u_short pro, hrd, op, linkaddr;
 362
 363         ap = (const struct arp_pkthdr *)bp;
 364         ND_TCHECK(*ap);
 365
 366         hrd = HRD(ap);
 367         pro = PRO(ap);
 368         op = OP(ap);
 369
 370
 371         /* if its ATM then call the ATM ARP printer
 372            for Frame-relay ARP most of the fields
 373            are similar to Ethernet so overload the Ethernet Printer
 374            and set the linkaddr type for linkaddr_string(ndo, ) accordingly */
 375
 376         switch(hrd) {
 377         case ARPHRD_ATM2225:
 378             atmarp_print(ndo, bp, length, caplen);
 379             return;
 380         case ARPHRD_FRELAY:
 381             linkaddr = LINKADDR_FRELAY;
 382             break;
 383         default:
 384             linkaddr = LINKADDR_ETHER;
 385             break;
 386         }
 387
 388         if (!ND_TTEST2(*TPA(ap), PROTO_LEN(ap))) {
 389                 ND_PRINT((ndo, "%s", tstr));
 390                 ND_DEFAULTPRINT((const u_char *)ap, length);
 391                 return;
 392         }
 393
 394         if (!ndo->ndo_eflag) {
 395             ND_PRINT((ndo, "ARP, "));
 396         }
 397
 398         /* print hardware type/len and proto type/len */
 399         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 400             PROTO_LEN(ap) != 4 ||
 401             HRD_LEN(ap) == 0 ||
 402             ndo->ndo_vflag) {
 403             ND_PRINT((ndo, "%s (len %u), %s (len %u)",
 404                       tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 405                       HRD_LEN(ap),
 406                       tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 407                       PROTO_LEN(ap)));
 408
 409             /* don't know know about the address formats */
 410             if (!ndo->ndo_vflag) {
 411                 goto out;
 412             }
 413         }
 414
 415         /* print operation */
 416         ND_PRINT((ndo, "%s%s ",
 417                ndo->ndo_vflag ? ", " : "",
 418                tok2str(arpop_values, "Unknown (%u)", op)));
 419
 420         switch (op) {
 421
 422         case ARPOP_REQUEST:
 423                 ND_PRINT((ndo, "who-has "));
 424                 tpaddr_print_ip(ndo, ap, pro);
 425                 if (isnonzero((const u_char *)THA(ap), HRD_LEN(ap)))
 426                         ND_PRINT((ndo, " (%s)",
 427                                   linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap))));
 428                 ND_PRINT((ndo, " tell "));
 429                 spaddr_print_ip(ndo, ap, pro);
 430                 break;
 431
 432         case ARPOP_REPLY:
 433                 spaddr_print_ip(ndo, ap, pro);
 434                 ND_PRINT((ndo, " is-at %s",
 435                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
 436                 break;
 437
 438         case ARPOP_REVREQUEST:
 439                 ND_PRINT((ndo, "who-is %s tell %s",
 440                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
 441                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
 442                 break;
 443
 444         case ARPOP_REVREPLY:
 445                 ND_PRINT((ndo, "%s at ",
 446                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap))));
 447                 tpaddr_print_ip(ndo, ap, pro);
 448                 break;
 449
 450         case ARPOP_INVREQUEST:
 451                 ND_PRINT((ndo, "who-is %s tell %s",
 452                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
 453                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
 454                 break;
 455
 456         case ARPOP_INVREPLY:
 457                 ND_PRINT((ndo,"%s at ",
 458                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
 459                 spaddr_print_ip(ndo, ap, pro);
 460                 break;
 461
 462         default:
 463                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 464                 return;
 465         }
 466
 467  out:
 468         ND_PRINT((ndo, ", length %u", length));
 469
 470         return;
 471 trunc:
 472         ND_PRINT((ndo, "%s", tstr));
 473 }
 474
 475 /*
 476  * Local Variables:
 477  * c-style: bsd
 478  * End:
 479  */
 480