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         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))+  EXTRACT_U_1((ap)->ar_hln))
  81 #define ar_tha(ap)      (((const u_char *)((ap)+1))+  EXTRACT_U_1((ap)->ar_hln)+EXTRACT_U_1((ap)->ar_pln))
  82 #define ar_tpa(ap)      (((const u_char *)((ap)+1))+2*EXTRACT_U_1((ap)->ar_hln)+EXTRACT_U_1((ap)->ar_pln))
  83 };
  84
  85 #define ARP_HDRLEN      8
  86
  87 #define HRD(ap) EXTRACT_BE_U_2((ap)->ar_hrd)
  88 #define HRD_LEN(ap) EXTRACT_U_1((ap)->ar_hln)
  89 #define PROTO_LEN(ap) EXTRACT_U_1((ap)->ar_pln)
  90 #define OP(ap)  EXTRACT_BE_U_2((ap)->ar_op)
  91 #define PRO(ap) EXTRACT_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     { 0, NULL }
 118 };
 119
 120 /*
 121  * ATM Address Resolution Protocol.
 122  *
 123  * See RFC 2225 for protocol description.  ATMARP packets are similar
 124  * to ARP packets, except that there are no length fields for the
 125  * protocol address - instead, there are type/length fields for
 126  * the ATM number and subaddress - and the hardware addresses consist
 127  * of an ATM number and an ATM subaddress.
 128  */
 129 struct  atmarp_pkthdr {
 130         nd_uint16_t aar_hrd;    /* format of hardware address */
 131         nd_uint16_t aar_pro;    /* format of protocol address */
 132         nd_uint8_t  aar_shtl;   /* length of source ATM number */
 133         nd_uint8_t  aar_sstl;   /* length of source ATM subaddress */
 134 #define ATMARP_IS_E164  0x40    /* bit in type/length for E.164 format */
 135 #define ATMARP_LEN_MASK 0x3F    /* length of {sub}address in type/length */
 136         nd_uint16_t aar_op;     /* same as regular ARP */
 137         nd_uint8_t  aar_spln;   /* length of source protocol address */
 138         nd_uint8_t  aar_thtl;   /* length of target ATM number */
 139         nd_uint8_t  aar_tstl;   /* length of target ATM subaddress */
 140         nd_uint8_t  aar_tpln;   /* length of target protocol address */
 141 /*
 142  * The remaining fields are variable in size,
 143  * according to the sizes above.
 144  */
 145 #ifdef COMMENT_ONLY
 146         nd_byte         aar_sha[];      /* source ATM number */
 147         nd_byte         aar_ssa[];      /* source ATM subaddress */
 148         nd_byte         aar_spa[];      /* sender protocol address */
 149         nd_byte         aar_tha[];      /* target ATM number */
 150         nd_byte         aar_tsa[];      /* target ATM subaddress */
 151         nd_byte         aar_tpa[];      /* target protocol address */
 152 #endif
 153
 154 #define ATMHRD(ap)  EXTRACT_BE_U_2((ap)->aar_hrd)
 155 #define ATMSHRD_LEN(ap) (EXTRACT_U_1((ap)->aar_shtl) & ATMARP_LEN_MASK)
 156 #define ATMSSLN(ap) (EXTRACT_U_1((ap)->aar_sstl) & ATMARP_LEN_MASK)
 157 #define ATMSPROTO_LEN(ap) EXTRACT_U_1((ap)->aar_spln)
 158 #define ATMOP(ap)   EXTRACT_BE_U_2((ap)->aar_op)
 159 #define ATMPRO(ap)  EXTRACT_BE_U_2((ap)->aar_pro)
 160 #define ATMTHRD_LEN(ap) (EXTRACT_U_1((ap)->aar_thtl) & ATMARP_LEN_MASK)
 161 #define ATMTSLN(ap) (EXTRACT_U_1((ap)->aar_tstl) & ATMARP_LEN_MASK)
 162 #define ATMTPROTO_LEN(ap) EXTRACT_U_1((ap)->aar_tpln)
 163 #define aar_sha(ap)     ((const u_char *)((ap)+1))
 164 #define aar_ssa(ap)     (aar_sha(ap) + ATMSHRD_LEN(ap))
 165 #define aar_spa(ap)     (aar_ssa(ap) + ATMSSLN(ap))
 166 #define aar_tha(ap)     (aar_spa(ap) + ATMSPROTO_LEN(ap))
 167 #define aar_tsa(ap)     (aar_tha(ap) + ATMTHRD_LEN(ap))
 168 #define aar_tpa(ap)     (aar_tsa(ap) + ATMTSLN(ap))
 169 };
 170
 171 #define ATMSHA(ap) (aar_sha(ap))
 172 #define ATMSSA(ap) (aar_ssa(ap))
 173 #define ATMSPA(ap) (aar_spa(ap))
 174 #define ATMTHA(ap) (aar_tha(ap))
 175 #define ATMTSA(ap) (aar_tsa(ap))
 176 #define ATMTPA(ap) (aar_tpa(ap))
 177
 178 static int
 179 isnonzero(const u_char *a, size_t len)
 180 {
 181         while (len > 0) {
 182                 if (EXTRACT_U_1(a) != 0)
 183                         return (1);
 184                 a++;
 185                 len--;
 186         }
 187         return (0);
 188 }
 189
 190 static void
 191 tpaddr_print_ip(netdissect_options *ndo,
 192                 const struct arp_pkthdr *ap, u_short pro)
 193 {
 194         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 195                 ND_PRINT("<wrong proto type>");
 196         else if (PROTO_LEN(ap) != 4)
 197                 ND_PRINT("<wrong len>");
 198         else
 199                 ND_PRINT("%s", ipaddr_string(ndo, TPA(ap)));
 200 }
 201
 202 static void
 203 spaddr_print_ip(netdissect_options *ndo,
 204                 const struct arp_pkthdr *ap, u_short pro)
 205 {
 206         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 207                 ND_PRINT("<wrong proto type>");
 208         else if (PROTO_LEN(ap) != 4)
 209                 ND_PRINT("<wrong len>");
 210         else
 211                 ND_PRINT("%s", ipaddr_string(ndo, SPA(ap)));
 212 }
 213
 214 static void
 215 atmarp_addr_print(netdissect_options *ndo,
 216                   const u_char *ha, u_int ha_len, const u_char *srca,
 217     u_int srca_len)
 218 {
 219         if (ha_len == 0)
 220                 ND_PRINT("<No address>");
 221         else {
 222                 ND_PRINT("%s", linkaddr_string(ndo, ha, LINKADDR_ATM, ha_len));
 223                 if (srca_len != 0)
 224                         ND_PRINT(",%s",
 225                                   linkaddr_string(ndo, srca, LINKADDR_ATM, srca_len));
 226         }
 227 }
 228
 229 static void
 230 atmarp_tpaddr_print(netdissect_options *ndo,
 231                     const struct atmarp_pkthdr *ap, u_short pro)
 232 {
 233         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 234                 ND_PRINT("<wrong proto type>");
 235         else if (ATMTPROTO_LEN(ap) != 4)
 236                 ND_PRINT("<wrong tplen>");
 237         else
 238                 ND_PRINT("%s", ipaddr_string(ndo, ATMTPA(ap)));
 239 }
 240
 241 static void
 242 atmarp_spaddr_print(netdissect_options *ndo,
 243                     const struct atmarp_pkthdr *ap, u_short pro)
 244 {
 245         if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
 246                 ND_PRINT("<wrong proto type>");
 247         else if (ATMSPROTO_LEN(ap) != 4)
 248                 ND_PRINT("<wrong splen>");
 249         else
 250                 ND_PRINT("%s", ipaddr_string(ndo, ATMSPA(ap)));
 251 }
 252
 253 static void
 254 atmarp_print(netdissect_options *ndo,
 255              const u_char *bp, u_int length, u_int caplen)
 256 {
 257         const struct atmarp_pkthdr *ap;
 258         u_short pro, hrd, op;
 259
 260         ap = (const struct atmarp_pkthdr *)bp;
 261         ND_TCHECK_SIZE(ap);
 262
 263         hrd = ATMHRD(ap);
 264         pro = ATMPRO(ap);
 265         op = ATMOP(ap);
 266
 267         if (!ND_TTEST_LEN(aar_tpa(ap), ATMTPROTO_LEN(ap))) {
 268                 nd_print_trunc(ndo);
 269                 ND_DEFAULTPRINT((const u_char *)ap, length);
 270                 return;
 271         }
 272
 273         if (!ndo->ndo_eflag) {
 274             ND_PRINT("ARP, ");
 275         }
 276
 277         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 278             ATMSPROTO_LEN(ap) != 4 ||
 279             ATMTPROTO_LEN(ap) != 4 ||
 280             ndo->ndo_vflag) {
 281                 ND_PRINT("%s, %s (len %u/%u)",
 282                           tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 283                           tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 284                           ATMSPROTO_LEN(ap),
 285                           ATMTPROTO_LEN(ap));
 286
 287                 /* don't know know about the address formats */
 288                 if (!ndo->ndo_vflag) {
 289                     goto out;
 290                 }
 291         }
 292
 293         /* print operation */
 294         ND_PRINT("%s%s ",
 295                ndo->ndo_vflag ? ", " : "",
 296                tok2str(arpop_values, "Unknown (%u)", op));
 297
 298         switch (op) {
 299
 300         case ARPOP_REQUEST:
 301                 ND_PRINT("who-has ");
 302                 atmarp_tpaddr_print(ndo, ap, pro);
 303                 if (ATMTHRD_LEN(ap) != 0) {
 304                         ND_PRINT(" (");
 305                         atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
 306                             ATMTSA(ap), ATMTSLN(ap));
 307                         ND_PRINT(")");
 308                 }
 309                 ND_PRINT(" tell ");
 310                 atmarp_spaddr_print(ndo, ap, pro);
 311                 break;
 312
 313         case ARPOP_REPLY:
 314                 atmarp_spaddr_print(ndo, ap, pro);
 315                 ND_PRINT(" is-at ");
 316                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 317                                   ATMSSLN(ap));
 318                 break;
 319
 320         case ARPOP_INVREQUEST:
 321                 ND_PRINT("who-is ");
 322                 atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
 323                     ATMTSLN(ap));
 324                 ND_PRINT(" tell ");
 325                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 326                     ATMSSLN(ap));
 327                 break;
 328
 329         case ARPOP_INVREPLY:
 330                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 331                     ATMSSLN(ap));
 332                 ND_PRINT("at ");
 333                 atmarp_spaddr_print(ndo, ap, pro);
 334                 break;
 335
 336         case ARPOP_NAK:
 337                 ND_PRINT("for ");
 338                 atmarp_spaddr_print(ndo, ap, pro);
 339                 break;
 340
 341         default:
 342                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 343                 return;
 344         }
 345
 346  out:
 347         ND_PRINT(", length %u", length);
 348         return;
 349
 350 trunc:
 351         nd_print_trunc(ndo);
 352 }
 353
 354 void
 355 arp_print(netdissect_options *ndo,
 356           const u_char *bp, u_int length, u_int caplen)
 357 {
 358         const struct arp_pkthdr *ap;
 359         u_short pro, hrd, op, linkaddr;
 360
 361         ndo->ndo_protocol = "arp";
 362         ap = (const struct arp_pkthdr *)bp;
 363         ND_TCHECK_SIZE(ap);
 364
 365         hrd = HRD(ap);
 366         pro = PRO(ap);
 367         op = OP(ap);
 368
 369
 370         /* if its ATM then call the ATM ARP printer
 371            for Frame-relay ARP most of the fields
 372            are similar to Ethernet so overload the Ethernet Printer
 373            and set the linkaddr type for linkaddr_string(ndo, ) accordingly */
 374
 375         switch(hrd) {
 376         case ARPHRD_ATM2225:
 377             atmarp_print(ndo, bp, length, caplen);
 378             return;
 379         case ARPHRD_FRELAY:
 380             linkaddr = LINKADDR_FRELAY;
 381             break;
 382         default:
 383             linkaddr = LINKADDR_ETHER;
 384             break;
 385         }
 386
 387         if (!ND_TTEST_LEN(TPA(ap), PROTO_LEN(ap))) {
 388                 nd_print_trunc(ndo);
 389                 ND_DEFAULTPRINT((const u_char *)ap, length);
 390                 return;
 391         }
 392
 393         if (!ndo->ndo_eflag) {
 394             ND_PRINT("ARP, ");
 395         }
 396
 397         /* print hardware type/len and proto type/len */
 398         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 399             PROTO_LEN(ap) != 4 ||
 400             HRD_LEN(ap) == 0 ||
 401             ndo->ndo_vflag) {
 402             ND_PRINT("%s (len %u), %s (len %u)",
 403                       tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 404                       HRD_LEN(ap),
 405                       tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 406                       PROTO_LEN(ap));
 407
 408             /* don't know know about the address formats */
 409             if (!ndo->ndo_vflag) {
 410                 goto out;
 411             }
 412         }
 413
 414         /* print operation */
 415         ND_PRINT("%s%s ",
 416                ndo->ndo_vflag ? ", " : "",
 417                tok2str(arpop_values, "Unknown (%u)", op));
 418
 419         switch (op) {
 420
 421         case ARPOP_REQUEST:
 422                 ND_PRINT("who-has ");
 423                 tpaddr_print_ip(ndo, ap, pro);
 424                 if (isnonzero((const u_char *)THA(ap), HRD_LEN(ap)))
 425                         ND_PRINT(" (%s)",
 426                                   linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)));
 427                 ND_PRINT(" tell ");
 428                 spaddr_print_ip(ndo, ap, pro);
 429                 break;
 430
 431         case ARPOP_REPLY:
 432                 spaddr_print_ip(ndo, ap, pro);
 433                 ND_PRINT(" is-at %s",
 434                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap)));
 435                 break;
 436
 437         case ARPOP_REVREQUEST:
 438                 ND_PRINT("who-is %s tell %s",
 439                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
 440                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap)));
 441                 break;
 442
 443         case ARPOP_REVREPLY:
 444                 ND_PRINT("%s at ",
 445                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)));
 446                 tpaddr_print_ip(ndo, ap, pro);
 447                 break;
 448
 449         case ARPOP_INVREQUEST:
 450                 ND_PRINT("who-is %s tell %s",
 451                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
 452                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap)));
 453                 break;
 454
 455         case ARPOP_INVREPLY:
 456                 ND_PRINT("%s at ",
 457                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap)));
 458                 spaddr_print_ip(ndo, ap, pro);
 459                 break;
 460
 461         default:
 462                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 463                 return;
 464         }
 465
 466  out:
 467         ND_PRINT(", length %u", length);
 468
 469         return;
 470 trunc:
 471         nd_print_trunc(ndo);
 472 }