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 "ethertype.h"
  35 #include "extract.h"
  36
  37
  38 /*
  39  * Address Resolution Protocol.
  40  *
  41  * See RFC 826 for protocol description.  ARP packets are variable
  42  * in size; the arphdr structure defines the fixed-length portion.
  43  * Protocol type values are the same as those for 10 Mb/s Ethernet.
  44  * It is followed by the variable-sized fields ar_sha, arp_spa,
  45  * arp_tha and arp_tpa in that order, according to the lengths
  46  * specified.  Field names used correspond to RFC 826.
  47  */
  48 struct  arp_pkthdr {
  49         nd_uint16_t ar_hrd;     /* format of hardware address */
  50 #define ARPHRD_ETHER    1       /* ethernet hardware format */
  51 #define ARPHRD_IEEE802  6       /* token-ring hardware format */
  52 #define ARPHRD_ARCNET   7       /* arcnet hardware format */
  53 #define ARPHRD_FRELAY   15      /* frame relay hardware format */
  54 #define ARPHRD_ATM2225  19      /* ATM (RFC 2225) */
  55 #define ARPHRD_STRIP    23      /* Ricochet Starmode Radio hardware format */
  56 #define ARPHRD_IEEE1394 24      /* IEEE 1394 (FireWire) hardware format */
  57 #define ARPHRD_INFINIBAND 32    /* InfiniBand RFC 4391 */
  58         nd_uint16_t ar_pro;     /* format of protocol address */
  59         nd_uint8_t  ar_hln;     /* length of hardware address */
  60         nd_uint8_t  ar_pln;     /* length of protocol address */
  61         nd_uint16_t ar_op;      /* one of: */
  62 #define ARPOP_REQUEST   1       /* request to resolve address */
  63 #define ARPOP_REPLY     2       /* response to previous request */
  64 #define ARPOP_REVREQUEST 3      /* request protocol address given hardware */
  65 #define ARPOP_REVREPLY  4       /* response giving protocol address */
  66 #define ARPOP_INVREQUEST 8      /* request to identify peer */
  67 #define ARPOP_INVREPLY  9       /* response identifying peer */
  68 #define ARPOP_NAK       10      /* NAK - only valif for ATM ARP */
  69
  70 /*
  71  * The remaining fields are variable in size,
  72  * according to the sizes above.
  73  */
  74 #ifdef COMMENT_ONLY
  75         nd_byte         ar_sha[];       /* sender hardware address */
  76         nd_byte         ar_spa[];       /* sender protocol address */
  77         nd_byte         ar_tha[];       /* target hardware address */
  78         nd_byte         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))+  GET_U_1((ap)->ar_hln))
  82 #define ar_tha(ap)      (((const u_char *)((ap)+1))+  GET_U_1((ap)->ar_hln)+GET_U_1((ap)->ar_pln))
  83 #define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*GET_U_1((ap)->ar_hln)+GET_U_1((ap)->ar_pln))
  84 };
  85
  86 #define ARP_HDRLEN      8
  87
  88 #define HRD(ap) GET_BE_U_2((ap)->ar_hrd)
  89 #define HRD_LEN(ap) GET_U_1((ap)->ar_hln)
  90 #define PROTO_LEN(ap) GET_U_1((ap)->ar_pln)
  91 #define OP(ap)  GET_BE_U_2((ap)->ar_op)
  92 #define PRO(ap) GET_BE_U_2((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 static const struct tok arpop_values[] = {
 100     { ARPOP_REQUEST, "Request" },
 101     { ARPOP_REPLY, "Reply" },
 102     { ARPOP_REVREQUEST, "Reverse Request" },
 103     { ARPOP_REVREPLY, "Reverse Reply" },
 104     { ARPOP_INVREQUEST, "Inverse Request" },
 105     { ARPOP_INVREPLY, "Inverse Reply" },
 106     { ARPOP_NAK, "NACK Reply" },
 107     { 0, NULL }
 108 };
 109
 110 static const struct tok arphrd_values[] = {
 111     { ARPHRD_ETHER, "Ethernet" },
 112     { ARPHRD_IEEE802, "TokenRing" },
 113     { ARPHRD_ARCNET, "ArcNet" },
 114     { ARPHRD_FRELAY, "FrameRelay" },
 115     { ARPHRD_STRIP, "Strip" },
 116     { ARPHRD_IEEE1394, "IEEE 1394" },
 117     { ARPHRD_ATM2225, "ATM" },
 118     { ARPHRD_INFINIBAND, "InfiniBand" },
 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         nd_uint16_t aar_hrd;    /* format of hardware address */
 133         nd_uint16_t aar_pro;    /* format of protocol address */
 134         nd_uint8_t  aar_shtl;   /* length of source ATM number */
 135         nd_uint8_t  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         nd_uint16_t aar_op;     /* same as regular ARP */
 139         nd_uint8_t  aar_spln;   /* length of source protocol address */
 140         nd_uint8_t  aar_thtl;   /* length of target ATM number */
 141         nd_uint8_t  aar_tstl;   /* length of target ATM subaddress */
 142         nd_uint8_t  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         nd_byte         aar_sha[];      /* source ATM number */
 149         nd_byte         aar_ssa[];      /* source ATM subaddress */
 150         nd_byte         aar_spa[];      /* sender protocol address */
 151         nd_byte         aar_tha[];      /* target ATM number */
 152         nd_byte         aar_tsa[];      /* target ATM subaddress */
 153         nd_byte         aar_tpa[];      /* target protocol address */
 154 #endif
 155
 156 #define ATMHRD(ap)  GET_BE_U_2((ap)->aar_hrd)
 157 #define ATMSHRD_LEN(ap) (GET_U_1((ap)->aar_shtl) & ATMARP_LEN_MASK)
 158 #define ATMSSLN(ap) (GET_U_1((ap)->aar_sstl) & ATMARP_LEN_MASK)
 159 #define ATMSPROTO_LEN(ap) GET_U_1((ap)->aar_spln)
 160 #define ATMOP(ap)   GET_BE_U_2((ap)->aar_op)
 161 #define ATMPRO(ap)  GET_BE_U_2((ap)->aar_pro)
 162 #define ATMTHRD_LEN(ap) (GET_U_1((ap)->aar_thtl) & ATMARP_LEN_MASK)
 163 #define ATMTSLN(ap) (GET_U_1((ap)->aar_tstl) & ATMARP_LEN_MASK)
 164 #define ATMTPROTO_LEN(ap) GET_U_1((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(netdissect_options *ndo, const u_char *a, size_t len)
 182 {
 183         while (len > 0) {
 184                 if (GET_U_1(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("<wrong proto type>");
 198         else if (PROTO_LEN(ap) != 4)
 199                 ND_PRINT("<wrong len>");
 200         else
 201                 ND_PRINT("%s", GET_IPADDR_STRING(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("<wrong proto type>");
 210         else if (PROTO_LEN(ap) != 4)
 211                 ND_PRINT("<wrong len>");
 212         else
 213                 ND_PRINT("%s", GET_IPADDR_STRING(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("<No address>");
 223         else {
 224                 ND_PRINT("%s", GET_LINKADDR_STRING(ha, LINKADDR_ATM, ha_len));
 225                 if (srca_len != 0)
 226                         ND_PRINT(",%s",
 227                                   GET_LINKADDR_STRING(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("<wrong proto type>");
 237         else if (ATMTPROTO_LEN(ap) != 4)
 238                 ND_PRINT("<wrong tplen>");
 239         else
 240                 ND_PRINT("%s", GET_IPADDR_STRING(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("<wrong proto type>");
 249         else if (ATMSPROTO_LEN(ap) != 4)
 250                 ND_PRINT("<wrong splen>");
 251         else
 252                 ND_PRINT("%s", GET_IPADDR_STRING(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_SIZE(ap);
 264
 265         hrd = ATMHRD(ap);
 266         pro = ATMPRO(ap);
 267         op = ATMOP(ap);
 268
 269         if (!ND_TTEST_LEN(aar_tpa(ap), ATMTPROTO_LEN(ap))) {
 270                 nd_print_trunc(ndo);
 271                 ND_DEFAULTPRINT((const u_char *)ap, length);
 272                 return;
 273         }
 274
 275         if (!ndo->ndo_eflag) {
 276             ND_PRINT("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("%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 about the address formats */
 290                 if (!ndo->ndo_vflag) {
 291                     goto out;
 292                 }
 293         }
 294
 295         /* print operation */
 296         ND_PRINT("%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("who-has ");
 304                 atmarp_tpaddr_print(ndo, ap, pro);
 305                 if (ATMTHRD_LEN(ap) != 0) {
 306                         ND_PRINT(" (");
 307                         atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
 308                             ATMTSA(ap), ATMTSLN(ap));
 309                         ND_PRINT(")");
 310                 }
 311                 ND_PRINT(" 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(" 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("who-is ");
 324                 atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
 325                     ATMTSLN(ap));
 326                 ND_PRINT(" 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("at ");
 335                 atmarp_spaddr_print(ndo, ap, pro);
 336                 break;
 337
 338         case ARPOP_NAK:
 339                 ND_PRINT("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(", length %u", length);
 350         return;
 351
 352 trunc:
 353         nd_print_trunc(ndo);
 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         ndo->ndo_protocol = "arp";
 364         ap = (const struct arp_pkthdr *)bp;
 365         ND_TCHECK_SIZE(ap);
 366
 367         hrd = HRD(ap);
 368         pro = PRO(ap);
 369         op = OP(ap);
 370
 371
 372         /* if its ATM then call the ATM ARP printer
 373            for Frame-relay ARP most of the fields
 374            are similar to Ethernet so overload the Ethernet Printer
 375            and set the linkaddr type for GET_LINKADDR_STRING() accordingly */
 376
 377         switch(hrd) {
 378         case ARPHRD_ATM2225:
 379             atmarp_print(ndo, bp, length, caplen);
 380             return;
 381         case ARPHRD_FRELAY:
 382             linkaddr = LINKADDR_FRELAY;
 383             break;
 384         default:
 385             linkaddr = LINKADDR_ETHER;
 386             break;
 387         }
 388
 389         if (!ND_TTEST_LEN(TPA(ap), PROTO_LEN(ap))) {
 390                 nd_print_trunc(ndo);
 391                 ND_DEFAULTPRINT((const u_char *)ap, length);
 392                 return;
 393         }
 394
 395         if (!ndo->ndo_eflag) {
 396             ND_PRINT("ARP, ");
 397         }
 398
 399         /* print hardware type/len and proto type/len */
 400         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 401             PROTO_LEN(ap) != 4 ||
 402             HRD_LEN(ap) == 0 ||
 403             ndo->ndo_vflag) {
 404             ND_PRINT("%s (len %u), %s (len %u)",
 405                       tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 406                       HRD_LEN(ap),
 407                       tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 408                       PROTO_LEN(ap));
 409
 410             /* don't know about the address formats */
 411             if (!ndo->ndo_vflag) {
 412                 goto out;
 413             }
 414         }
 415
 416         /* print operation */
 417         ND_PRINT("%s%s ",
 418                ndo->ndo_vflag ? ", " : "",
 419                tok2str(arpop_values, "Unknown (%u)", op));
 420
 421         switch (op) {
 422
 423         case ARPOP_REQUEST:
 424                 ND_PRINT("who-has ");
 425                 tpaddr_print_ip(ndo, ap, pro);
 426                 if (isnonzero(ndo, (const u_char *)THA(ap), HRD_LEN(ap)))
 427                         ND_PRINT(" (%s)",
 428                                   GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)));
 429                 ND_PRINT(" tell ");
 430                 spaddr_print_ip(ndo, ap, pro);
 431                 break;
 432
 433         case ARPOP_REPLY:
 434                 spaddr_print_ip(ndo, ap, pro);
 435                 ND_PRINT(" is-at %s",
 436                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 437                 break;
 438
 439         case ARPOP_REVREQUEST:
 440                 ND_PRINT("who-is %s tell %s",
 441                           GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)),
 442                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 443                 break;
 444
 445         case ARPOP_REVREPLY:
 446                 ND_PRINT("%s at ",
 447                           GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)));
 448                 tpaddr_print_ip(ndo, ap, pro);
 449                 break;
 450
 451         case ARPOP_INVREQUEST:
 452                 ND_PRINT("who-is %s tell %s",
 453                           GET_LINKADDR_STRING(THA(ap), linkaddr, HRD_LEN(ap)),
 454                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 455                 break;
 456
 457         case ARPOP_INVREPLY:
 458                 ND_PRINT("%s at ",
 459                           GET_LINKADDR_STRING(SHA(ap), linkaddr, HRD_LEN(ap)));
 460                 spaddr_print_ip(ndo, ap, pro);
 461                 break;
 462
 463         default:
 464                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 465                 return;
 466         }
 467
 468  out:
 469         ND_PRINT(", length %u", length);
 470
 471         return;
 472 trunc:
 473         nd_print_trunc(ndo);
 474 }