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 #define ND_LONGJMP_FROM_TCHECK
  31 #include "netdissect.h"
  32 #include "addrtoname.h"
  33 #include "ethertype.h"
  34 #include "extract.h"
  35
  36
  37 /*
  38  * Address Resolution Protocol.
  39  *
  40  * See RFC 826 for protocol description.  ARP packets are variable
  41  * in size; the arphdr structure defines the fixed-length portion.
  42  * Protocol type values are the same as those for 10 Mb/s Ethernet.
  43  * It is followed by the variable-sized fields ar_sha, arp_spa,
  44  * arp_tha and arp_tpa in that order, according to the lengths
  45  * specified.  Field names used correspond to RFC 826.
  46  */
  47 struct  arp_pkthdr {
  48         nd_uint16_t ar_hrd;     /* format of hardware address */
  49 #define ARPHRD_ETHER    1       /* ethernet hardware format */
  50 #define ARPHRD_IEEE802  6       /* token-ring hardware format */
  51 #define ARPHRD_ARCNET   7       /* arcnet hardware format */
  52 #define ARPHRD_FRELAY   15      /* frame relay hardware format */
  53 #define ARPHRD_ATM2225  19      /* ATM (RFC 2225) */
  54 #define ARPHRD_STRIP    23      /* Ricochet Starmode Radio hardware format */
  55 #define ARPHRD_IEEE1394 24      /* IEEE 1394 (FireWire) hardware format */
  56 #define ARPHRD_INFINIBAND 32    /* InfiniBand RFC 4391 */
  57         nd_uint16_t ar_pro;     /* format of protocol address */
  58         nd_uint8_t  ar_hln;     /* length of hardware address */
  59         nd_uint8_t  ar_pln;     /* length of protocol address */
  60         nd_uint16_t ar_op;      /* one of: */
  61 #define ARPOP_REQUEST   1       /* request to resolve address */
  62 #define ARPOP_REPLY     2       /* response to previous request */
  63 #define ARPOP_REVREQUEST 3      /* request protocol address given hardware */
  64 #define ARPOP_REVREPLY  4       /* response giving protocol address */
  65 #define ARPOP_INVREQUEST 8      /* request to identify peer */
  66 #define ARPOP_INVREPLY  9       /* response identifying peer */
  67 #define ARPOP_NAK       10      /* NAK - only valif for ATM ARP */
  68
  69 /*
  70  * The remaining fields are variable in size,
  71  * according to the sizes above.
  72  */
  73 #ifdef COMMENT_ONLY
  74         nd_byte         ar_sha[];       /* sender hardware address */
  75         nd_byte         ar_spa[];       /* sender protocol address */
  76         nd_byte         ar_tha[];       /* target hardware address */
  77         nd_byte         ar_tpa[];       /* target protocol address */
  78 #endif
  79 #define ar_sha(ap)      (((const u_char *)((ap)+1))+  0)
  80 #define ar_spa(ap)      (((const u_char *)((ap)+1))+  GET_U_1((ap)->ar_hln))
  81 #define ar_tha(ap)      (((const u_char *)((ap)+1))+  GET_U_1((ap)->ar_hln)+GET_U_1((ap)->ar_pln))
  82 #define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*GET_U_1((ap)->ar_hln)+GET_U_1((ap)->ar_pln))
  83 };
  84
  85 #define ARP_HDRLEN      8
  86
  87 #define HRD(ap) GET_BE_U_2((ap)->ar_hrd)
  88 #define HRD_LEN(ap) GET_U_1((ap)->ar_hln)
  89 #define PROTO_LEN(ap) GET_U_1((ap)->ar_pln)
  90 #define OP(ap)  GET_BE_U_2((ap)->ar_op)
  91 #define PRO(ap) GET_BE_U_2((ap)->ar_pro)
  92 #define SHA(ap) (ar_sha(ap))
  93 #define SPA(ap) (ar_spa(ap))
  94 #define THA(ap) (ar_tha(ap))
  95 #define TPA(ap) (ar_tpa(ap))
  96
  97
  98 static const struct tok arpop_values[] = {
  99     { ARPOP_REQUEST, "Request" },
 100     { ARPOP_REPLY, "Reply" },
 101     { ARPOP_REVREQUEST, "Reverse Request" },
 102     { ARPOP_REVREPLY, "Reverse Reply" },
 103     { ARPOP_INVREQUEST, "Inverse Request" },
 104     { ARPOP_INVREPLY, "Inverse Reply" },
 105     { ARPOP_NAK, "NACK Reply" },
 106     { 0, NULL }
 107 };
 108
 109 static const struct tok arphrd_values[] = {
 110     { ARPHRD_ETHER, "Ethernet" },
 111     { ARPHRD_IEEE802, "TokenRing" },
 112     { ARPHRD_ARCNET, "ArcNet" },
 113     { ARPHRD_FRELAY, "FrameRelay" },
 114     { ARPHRD_STRIP, "Strip" },
 115     { ARPHRD_IEEE1394, "IEEE 1394" },
 116     { ARPHRD_ATM2225, "ATM" },
 117     { ARPHRD_INFINIBAND, "InfiniBand" },
 118     { 0, NULL }
 119 };
 120
 121 /*
 122  * ATM Address Resolution Protocol.
 123  *
 124  * See RFC 2225 for protocol description.  ATMARP packets are similar
 125  * to ARP packets, except that there are no length fields for the
 126  * protocol address - instead, there are type/length fields for
 127  * the ATM number and subaddress - and the hardware addresses consist
 128  * of an ATM number and an ATM subaddress.
 129  */
 130 struct  atmarp_pkthdr {
 131         nd_uint16_t aar_hrd;    /* format of hardware address */
 132         nd_uint16_t aar_pro;    /* format of protocol address */
 133         nd_uint8_t  aar_shtl;   /* length of source ATM number */
 134         nd_uint8_t  aar_sstl;   /* length of source ATM subaddress */
 135 #define ATMARP_IS_E164  0x40    /* bit in type/length for E.164 format */
 136 #define ATMARP_LEN_MASK 0x3F    /* length of {sub}address in type/length */
 137         nd_uint16_t aar_op;     /* same as regular ARP */
 138         nd_uint8_t  aar_spln;   /* length of source protocol address */
 139         nd_uint8_t  aar_thtl;   /* length of target ATM number */
 140         nd_uint8_t  aar_tstl;   /* length of target ATM subaddress */
 141         nd_uint8_t  aar_tpln;   /* length of target protocol address */
 142 /*
 143  * The remaining fields are variable in size,
 144  * according to the sizes above.
 145  */
 146 #ifdef COMMENT_ONLY
 147         nd_byte         aar_sha[];      /* source ATM number */
 148         nd_byte         aar_ssa[];      /* source ATM subaddress */
 149         nd_byte         aar_spa[];      /* sender protocol address */
 150         nd_byte         aar_tha[];      /* target ATM number */
 151         nd_byte         aar_tsa[];      /* target ATM subaddress */
 152         nd_byte         aar_tpa[];      /* target protocol address */
 153 #endif
 154
 155 #define ATMHRD(ap)  GET_BE_U_2((ap)->aar_hrd)
 156 #define ATMSHRD_LEN(ap) (GET_U_1((ap)->aar_shtl) & ATMARP_LEN_MASK)
 157 #define ATMSSLN(ap) (GET_U_1((ap)->aar_sstl) & ATMARP_LEN_MASK)
 158 #define ATMSPROTO_LEN(ap) GET_U_1((ap)->aar_spln)
 159 #define ATMOP(ap)   GET_BE_U_2((ap)->aar_op)
 160 #define ATMPRO(ap)  GET_BE_U_2((ap)->aar_pro)
 161 #define ATMTHRD_LEN(ap) (GET_U_1((ap)->aar_thtl) & ATMARP_LEN_MASK)
 162 #define ATMTSLN(ap) (GET_U_1((ap)->aar_tstl) & ATMARP_LEN_MASK)
 163 #define ATMTPROTO_LEN(ap) GET_U_1((ap)->aar_tpln)
 164 #define aar_sha(ap)     ((const u_char *)((ap)+1))
 165 #define aar_ssa(ap)     (aar_sha(ap) + ATMSHRD_LEN(ap))
 166 #define aar_spa(ap)     (aar_ssa(ap) + ATMSSLN(ap))
 167 #define aar_tha(ap)     (aar_spa(ap) + ATMSPROTO_LEN(ap))
 168 #define aar_tsa(ap)     (aar_tha(ap) + ATMTHRD_LEN(ap))
 169 #define aar_tpa(ap)     (aar_tsa(ap) + ATMTSLN(ap))
 170 };
 171
 172 #define ATMSHA(ap) (aar_sha(ap))
 173 #define ATMSSA(ap) (aar_ssa(ap))
 174 #define ATMSPA(ap) (aar_spa(ap))
 175 #define ATMTHA(ap) (aar_tha(ap))
 176 #define ATMTSA(ap) (aar_tsa(ap))
 177 #define ATMTPA(ap) (aar_tpa(ap))
 178
 179 static int
 180 isnonzero(netdissect_options *ndo, const u_char *a, size_t len)
 181 {
 182         while (len > 0) {
 183                 if (GET_U_1(a) != 0)
 184                         return (1);
 185                 a++;
 186                 len--;
 187         }
 188         return (0);
 189 }
 190
 191 static void
 192 tpaddr_print_ip(netdissect_options *ndo,
 193                 const struct arp_pkthdr *ap, u_short pro)
 194 {
 195         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 196                 ND_PRINT("<wrong proto type>");
 197         else if (PROTO_LEN(ap) != 4)
 198                 ND_PRINT("<wrong len>");
 199         else
 200                 ND_PRINT("%s", GET_IPADDR_STRING(TPA(ap)));
 201 }
 202
 203 static void
 204 spaddr_print_ip(netdissect_options *ndo,
 205                 const struct arp_pkthdr *ap, u_short pro)
 206 {
 207         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 208                 ND_PRINT("<wrong proto type>");
 209         else if (PROTO_LEN(ap) != 4)
 210                 ND_PRINT("<wrong len>");
 211         else
 212                 ND_PRINT("%s", GET_IPADDR_STRING(SPA(ap)));
 213 }
 214
 215 static void
 216 atmarp_addr_print(netdissect_options *ndo,
 217                   const u_char *ha, u_int ha_len, const u_char *srca,
 218     u_int srca_len)
 219 {
 220         if (ha_len == 0)
 221                 ND_PRINT("<No address>");
 222         else {
 223                 ND_PRINT("%s", GET_LINKADDR_STRING(ha, LINKADDR_ATM, ha_len));
 224                 if (srca_len != 0)
 225                         ND_PRINT(",%s",
 226                                   GET_LINKADDR_STRING(srca, LINKADDR_ATM, srca_len));
 227         }
 228 }
 229
 230 static void
 231 atmarp_tpaddr_print(netdissect_options *ndo,
 232                     const struct atmarp_pkthdr *ap, u_short pro)
 233 {
 234         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 235                 ND_PRINT("<wrong proto type>");
 236         else if (ATMTPROTO_LEN(ap) != 4)
 237                 ND_PRINT("<wrong tplen>");
 238         else
 239                 ND_PRINT("%s", GET_IPADDR_STRING(ATMTPA(ap)));
 240 }
 241
 242 static void
 243 atmarp_spaddr_print(netdissect_options *ndo,
 244                     const struct atmarp_pkthdr *ap, u_short pro)
 245 {
 246         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 247                 ND_PRINT("<wrong proto type>");
 248         else if (ATMSPROTO_LEN(ap) != 4)
 249                 ND_PRINT("<wrong splen>");
 250         else
 251                 ND_PRINT("%s", GET_IPADDR_STRING(ATMSPA(ap)));
 252 }
 253
 254 static void
 255 atmarp_print(netdissect_options *ndo,
 256              const u_char *bp, u_int length, u_int caplen)
 257 {
 258         const struct atmarp_pkthdr *ap;
 259         u_short pro, hrd, op;
 260
 261         ap = (const struct atmarp_pkthdr *)bp;
 262         ND_TCHECK_SIZE(ap);
 263
 264         hrd = ATMHRD(ap);
 265         pro = ATMPRO(ap);
 266         op = ATMOP(ap);
 267
 268         ND_TCHECK_LEN(ATMTPA(ap), ATMTPROTO_LEN(ap));
 269
 270         if (!ndo->ndo_eflag) {
 271             ND_PRINT("ARP, ");
 272         }
 273
 274         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 275             ATMSPROTO_LEN(ap) != 4 ||
 276             ATMTPROTO_LEN(ap) != 4 ||
 277             ndo->ndo_vflag) {
 278                 ND_PRINT("%s, %s (len %u/%u)",
 279                           tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 280                           tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 281                           ATMSPROTO_LEN(ap),
 282                           ATMTPROTO_LEN(ap));
 283
 284                 /* don't know about the address formats */
 285                 if (!ndo->ndo_vflag) {
 286                     goto out;
 287                 }
 288         }
 289
 290         /* print operation */
 291         ND_PRINT("%s%s ",
 292                ndo->ndo_vflag ? ", " : "",
 293                tok2str(arpop_values, "Unknown (%u)", op));
 294
 295         switch (op) {
 296
 297         case ARPOP_REQUEST:
 298                 ND_PRINT("who-has ");
 299                 atmarp_tpaddr_print(ndo, ap, pro);
 300                 if (ATMTHRD_LEN(ap) != 0) {
 301                         ND_PRINT(" (");
 302                         atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
 303                             ATMTSA(ap), ATMTSLN(ap));
 304                         ND_PRINT(")");
 305                 }
 306                 ND_PRINT(" tell ");
 307                 atmarp_spaddr_print(ndo, ap, pro);
 308                 break;
 309
 310         case ARPOP_REPLY:
 311                 atmarp_spaddr_print(ndo, ap, pro);
 312                 ND_PRINT(" is-at ");
 313                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 314                                   ATMSSLN(ap));
 315                 break;
 316
 317         case ARPOP_INVREQUEST:
 318                 ND_PRINT("who-is ");
 319                 atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
 320                     ATMTSLN(ap));
 321                 ND_PRINT(" tell ");
 322                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 323                     ATMSSLN(ap));
 324                 break;
 325
 326         case ARPOP_INVREPLY:
 327                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 328                     ATMSSLN(ap));
 329                 ND_PRINT("at ");
 330                 atmarp_spaddr_print(ndo, ap, pro);
 331                 break;
 332
 333         case ARPOP_NAK:
 334                 ND_PRINT("for ");
 335                 atmarp_spaddr_print(ndo, ap, pro);
 336                 break;
 337
 338         default:
 339                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 340                 return;
 341         }
 342
 343  out:
 344         ND_PRINT(", length %u", length);
 345 }
 346
 347 void
 348 arp_print(netdissect_options *ndo,
 349           const u_char *bp, u_int length, u_int caplen)
 350 {
 351         const struct arp_pkthdr *ap;
 352         u_short pro, hrd, op, linkaddr;
 353
 354         ndo->ndo_protocol = "arp";
 355         ap = (const struct arp_pkthdr *)bp;
 356         ND_TCHECK_SIZE(ap);
 357
 358         hrd = HRD(ap);
 359         pro = PRO(ap);
 360         op = OP(ap);
 361
 362
 363         /* if its ATM then call the ATM ARP printer
 364            for Frame-relay ARP most of the fields
 365            are similar to Ethernet so overload the Ethernet Printer
 366            and set the linkaddr type for GET_LINKADDR_STRING() accordingly */
 367
 368         switch(hrd) {
 369         case ARPHRD_ATM2225:
 370             atmarp_print(ndo, bp, length, caplen);
 371             return;
 372         case ARPHRD_FRELAY:
 373             linkaddr = LINKADDR_FRELAY;
 374             break;
 375         default:
 376             linkaddr = LINKADDR_ETHER;
 377             break;
 378         }
 379
 380         ND_TCHECK_LEN(TPA(ap), PROTO_LEN(ap));
 381
 382         if (!ndo->ndo_eflag) {
 383             ND_PRINT("ARP, ");
 384         }
 385
 386         /* print hardware type/len and proto type/len */
 387         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 388             PROTO_LEN(ap) != 4 ||
 389             HRD_LEN(ap) == 0 ||
 390             ndo->ndo_vflag) {
 391             ND_PRINT("%s (len %u), %s (len %u)",
 392                       tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 393                       HRD_LEN(ap),
 394                       tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 395                       PROTO_LEN(ap));
 396
 397             /* don't know about the address formats */
 398             if (!ndo->ndo_vflag) {
 399                 goto out;
 400             }
 401         }
 402
 403         /* print operation */
 404         ND_PRINT("%s%s ",
 405                ndo->ndo_vflag ? ", " : "",
 406                tok2str(arpop_values, "Unknown (%u)", op));
 407
 408         switch (op) {
 409
 410         case ARPOP_REQUEST:
 411                 ND_PRINT("who-has ");
 412                 tpaddr_print_ip(ndo, ap, pro);
 413                 if (isnonzero(ndo, (const u_char *)THA(ap), HRD_LEN(ap)))
 414                         ND_PRINT(" (%s)",
 415                                   GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)));
 416                 ND_PRINT(" tell ");
 417                 spaddr_print_ip(ndo, ap, pro);
 418                 break;
 419
 420         case ARPOP_REPLY:
 421                 spaddr_print_ip(ndo, ap, pro);
 422                 ND_PRINT(" is-at %s",
 423                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 424                 break;
 425
 426         case ARPOP_REVREQUEST:
 427                 /*
 428                  * XXX - GET_LINKADDR_STRING() may return a pointer to
 429                  * a static buffer, so we only have one call to it per
 430                  * ND_PRINT() call.
 431                  *
 432                  * This should be done in a cleaner fashion.
 433                  */
 434                 ND_PRINT("who-is %s",
 435                           GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)));
 436                 ND_PRINT(" tell %s",
 437                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 438                 break;
 439
 440         case ARPOP_REVREPLY:
 441                 ND_PRINT("%s at ",
 442                           GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)));
 443                 tpaddr_print_ip(ndo, ap, pro);
 444                 break;
 445
 446         case ARPOP_INVREQUEST:
 447                 /*
 448                  * XXX - GET_LINKADDR_STRING() may return a pointer to
 449                  * a static buffer, so we only have one call to it per
 450                  * ND_PRINT() call.
 451                  *
 452                  * This should be done in a cleaner fashion.
 453                  */
 454                 ND_PRINT("who-is %s",
 455                           GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)));
 456                 ND_PRINT(" tell %s",
 457                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 458                 break;
 459
 460         case ARPOP_INVREPLY:
 461                 ND_PRINT("%s at ",
 462                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 463                 spaddr_print_ip(ndo, ap, pro);
 464                 break;
 465
 466         default:
 467                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 468                 return;
 469         }
 470
 471  out:
 472         ND_PRINT(", length %u", length);
 473 }