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 static const char tstr[] = "[|ARP]";
  38
  39 /*
  40  * Address Resolution Protocol.
  41  *
  42  * See RFC 826 for protocol description.  ARP packets are variable
  43  * in size; the arphdr structure defines the fixed-length portion.
  44  * Protocol type values are the same as those for 10 Mb/s Ethernet.
  45  * It is followed by the variable-sized fields ar_sha, arp_spa,
  46  * arp_tha and arp_tpa in that order, according to the lengths
  47  * specified.  Field names used correspond to RFC 826.
  48  */
  49 struct  arp_pkthdr {
  50         nd_uint16_t ar_hrd;     /* format of hardware address */
  51 #define ARPHRD_ETHER    1       /* ethernet hardware format */
  52 #define ARPHRD_IEEE802  6       /* token-ring hardware format */
  53 #define ARPHRD_ARCNET   7       /* arcnet hardware format */
  54 #define ARPHRD_FRELAY   15      /* frame relay hardware format */
  55 #define ARPHRD_ATM2225  19      /* ATM (RFC 2225) */
  56 #define ARPHRD_STRIP    23      /* Ricochet Starmode Radio hardware format */
  57 #define ARPHRD_IEEE1394 24      /* IEEE 1394 (FireWire) hardware format */
  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))+  EXTRACT_U_1((ap)->ar_hln))
  82 #define ar_tha(ap)      (((const u_char *)((ap)+1))+  EXTRACT_U_1((ap)->ar_hln)+EXTRACT_U_1((ap)->ar_pln))
  83 #define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*EXTRACT_U_1((ap)->ar_hln)+EXTRACT_U_1((ap)->ar_pln))
  84 };
  85
  86 #define ARP_HDRLEN      8
  87
  88 #define HRD(ap) EXTRACT_BE_U_2((ap)->ar_hrd)
  89 #define HRD_LEN(ap) EXTRACT_U_1((ap)->ar_hln)
  90 #define PROTO_LEN(ap) EXTRACT_U_1((ap)->ar_pln)
  91 #define OP(ap)  EXTRACT_BE_U_2((ap)->ar_op)
  92 #define PRO(ap) EXTRACT_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     { 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)  EXTRACT_BE_U_2((ap)->aar_hrd)
 156 #define ATMSHRD_LEN(ap) (EXTRACT_U_1((ap)->aar_shtl) & ATMARP_LEN_MASK)
 157 #define ATMSSLN(ap) (EXTRACT_U_1((ap)->aar_sstl) & ATMARP_LEN_MASK)
 158 #define ATMSPROTO_LEN(ap) EXTRACT_U_1((ap)->aar_spln)
 159 #define ATMOP(ap)   EXTRACT_BE_U_2((ap)->aar_op)
 160 #define ATMPRO(ap)  EXTRACT_BE_U_2((ap)->aar_pro)
 161 #define ATMTHRD_LEN(ap) (EXTRACT_U_1((ap)->aar_thtl) & ATMARP_LEN_MASK)
 162 #define ATMTSLN(ap) (EXTRACT_U_1((ap)->aar_tstl) & ATMARP_LEN_MASK)
 163 #define ATMTPROTO_LEN(ap) EXTRACT_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(const u_char *a, size_t len)
 181 {
 182         while (len > 0) {
 183                 if (EXTRACT_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", ipaddr_string(ndo, 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", ipaddr_string(ndo, 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", linkaddr_string(ndo, ha, LINKADDR_ATM, ha_len));
 224                 if (srca_len != 0)
 225                         ND_PRINT(",%s",
 226                                   linkaddr_string(ndo, 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", ipaddr_string(ndo, 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", ipaddr_string(ndo, 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         if (!ND_TTEST_LEN(aar_tpa(ap), ATMTPROTO_LEN(ap))) {
 269                 ND_PRINT("%s", tstr);
 270                 ND_DEFAULTPRINT((const u_char *)ap, length);
 271                 return;
 272         }
 273
 274         if (!ndo->ndo_eflag) {
 275             ND_PRINT("ARP, ");
 276         }
 277
 278         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 279             ATMSPROTO_LEN(ap) != 4 ||
 280             ATMTPROTO_LEN(ap) != 4 ||
 281             ndo->ndo_vflag) {
 282                 ND_PRINT("%s, %s (len %u/%u)",
 283                           tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 284                           tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 285                           ATMSPROTO_LEN(ap),
 286                           ATMTPROTO_LEN(ap));
 287
 288                 /* don't know know about the address formats */
 289                 if (!ndo->ndo_vflag) {
 290                     goto out;
 291                 }
 292         }
 293
 294         /* print operation */
 295         ND_PRINT("%s%s ",
 296                ndo->ndo_vflag ? ", " : "",
 297                tok2str(arpop_values, "Unknown (%u)", op));
 298
 299         switch (op) {
 300
 301         case ARPOP_REQUEST:
 302                 ND_PRINT("who-has ");
 303                 atmarp_tpaddr_print(ndo, ap, pro);
 304                 if (ATMTHRD_LEN(ap) != 0) {
 305                         ND_PRINT(" (");
 306                         atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
 307                             ATMTSA(ap), ATMTSLN(ap));
 308                         ND_PRINT(")");
 309                 }
 310                 ND_PRINT(" tell ");
 311                 atmarp_spaddr_print(ndo, ap, pro);
 312                 break;
 313
 314         case ARPOP_REPLY:
 315                 atmarp_spaddr_print(ndo, ap, pro);
 316                 ND_PRINT(" is-at ");
 317                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 318                                   ATMSSLN(ap));
 319                 break;
 320
 321         case ARPOP_INVREQUEST:
 322                 ND_PRINT("who-is ");
 323                 atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
 324                     ATMTSLN(ap));
 325                 ND_PRINT(" tell ");
 326                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 327                     ATMSSLN(ap));
 328                 break;
 329
 330         case ARPOP_INVREPLY:
 331                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 332                     ATMSSLN(ap));
 333                 ND_PRINT("at ");
 334                 atmarp_spaddr_print(ndo, ap, pro);
 335                 break;
 336
 337         case ARPOP_NAK:
 338                 ND_PRINT("for ");
 339                 atmarp_spaddr_print(ndo, ap, pro);
 340                 break;
 341
 342         default:
 343                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 344                 return;
 345         }
 346
 347  out:
 348         ND_PRINT(", length %u", length);
 349         return;
 350
 351 trunc:
 352         ND_PRINT("%s", tstr);
 353 }
 354
 355 void
 356 arp_print(netdissect_options *ndo,
 357           const u_char *bp, u_int length, u_int caplen)
 358 {
 359         const struct arp_pkthdr *ap;
 360         u_short pro, hrd, op, linkaddr;
 361
 362         ndo->ndo_protocol = "arp";
 363         ap = (const struct arp_pkthdr *)bp;
 364         ND_TCHECK_SIZE(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_TTEST_LEN(TPA(ap), PROTO_LEN(ap))) {
 389                 ND_PRINT("%s", tstr);
 390                 ND_DEFAULTPRINT((const u_char *)ap, length);
 391                 return;
 392         }
 393
 394         if (!ndo->ndo_eflag) {
 395             ND_PRINT("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("%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("%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("who-has ");
 424                 tpaddr_print_ip(ndo, ap, pro);
 425                 if (isnonzero((const u_char *)THA(ap), HRD_LEN(ap)))
 426                         ND_PRINT(" (%s)",
 427                                   linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)));
 428                 ND_PRINT(" 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(" is-at %s",
 435                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap)));
 436                 break;
 437
 438         case ARPOP_REVREQUEST:
 439                 ND_PRINT("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("%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("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("%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(", length %u", length);
 469
 470         return;
 471 trunc:
 472         ND_PRINT("%s", tstr);
 473 }