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_16BITS(&(ap)->ar_hrd)
  90 #define HRD_LEN(ap) ((ap)->ar_hln)
  91 #define PROTO_LEN(ap) ((ap)->ar_pln)
  92 #define OP(ap)  EXTRACT_16BITS(&(ap)->ar_op)
  93 #define PRO(ap) EXTRACT_16BITS(&(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_16BITS(&(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_16BITS(&(ap)->aar_op)
 161 #define ATMPRO(ap)  EXTRACT_16BITS(&(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 atmarp_addr_print(netdissect_options *ndo,
 194                   const u_char *ha, u_int ha_len, const u_char *srca,
 195     u_int srca_len)
 196 {
 197         if (ha_len == 0)
 198                 ND_PRINT((ndo, "<No address>"));
 199         else {
 200                 ND_PRINT((ndo, "%s", linkaddr_string(ndo, ha, LINKADDR_ATM, ha_len)));
 201                 if (srca_len != 0)
 202                         ND_PRINT((ndo, ",%s",
 203                                   linkaddr_string(ndo, srca, LINKADDR_ATM, srca_len)));
 204         }
 205 }
 206
 207 static void
 208 atmarp_print(netdissect_options *ndo,
 209              const u_char *bp, u_int length, u_int caplen)
 210 {
 211         const struct atmarp_pkthdr *ap;
 212         u_short pro, hrd, op;
 213
 214         ap = (const struct atmarp_pkthdr *)bp;
 215         ND_TCHECK(*ap);
 216
 217         hrd = ATMHRD(ap);
 218         pro = ATMPRO(ap);
 219         op = ATMOP(ap);
 220
 221         if (!ND_TTEST2(*aar_tpa(ap), ATMTPROTO_LEN(ap))) {
 222                 ND_PRINT((ndo, "%s", tstr));
 223                 ND_DEFAULTPRINT((const u_char *)ap, length);
 224                 return;
 225         }
 226
 227         if (!ndo->ndo_eflag) {
 228             ND_PRINT((ndo, "ARP, "));
 229         }
 230
 231         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 232             ATMSPROTO_LEN(ap) != 4 ||
 233             ATMTPROTO_LEN(ap) != 4 ||
 234             ndo->ndo_vflag) {
 235                 ND_PRINT((ndo, "%s, %s (len %u/%u)",
 236                           tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 237                           tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 238                           ATMSPROTO_LEN(ap),
 239                           ATMTPROTO_LEN(ap)));
 240
 241                 /* don't know know about the address formats */
 242                 if (!ndo->ndo_vflag) {
 243                     goto out;
 244                 }
 245         }
 246
 247         /* print operation */
 248         ND_PRINT((ndo, "%s%s ",
 249                ndo->ndo_vflag ? ", " : "",
 250                tok2str(arpop_values, "Unknown (%u)", op)));
 251
 252         switch (op) {
 253
 254         case ARPOP_REQUEST:
 255                 ND_PRINT((ndo, "who-has %s", ipaddr_string(ndo, ATMTPA(ap))));
 256                 if (ATMTHRD_LEN(ap) != 0) {
 257                         ND_PRINT((ndo, " ("));
 258                         atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
 259                             ATMTSA(ap), ATMTSLN(ap));
 260                         ND_PRINT((ndo, ")"));
 261                 }
 262                 ND_PRINT((ndo, "tell %s", ipaddr_string(ndo, ATMSPA(ap))));
 263                 break;
 264
 265         case ARPOP_REPLY:
 266                 ND_PRINT((ndo, "%s is-at ", ipaddr_string(ndo, ATMSPA(ap))));
 267                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 268                                   ATMSSLN(ap));
 269                 break;
 270
 271         case ARPOP_INVREQUEST:
 272                 ND_PRINT((ndo, "who-is "));
 273                 atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
 274                     ATMTSLN(ap));
 275                 ND_PRINT((ndo, " tell "));
 276                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 277                     ATMSSLN(ap));
 278                 break;
 279
 280         case ARPOP_INVREPLY:
 281                 atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
 282                     ATMSSLN(ap));
 283                 ND_PRINT((ndo, "at %s", ipaddr_string(ndo, ATMSPA(ap))));
 284                 break;
 285
 286         case ARPOP_NAK:
 287                 ND_PRINT((ndo, "for %s", ipaddr_string(ndo, ATMSPA(ap))));
 288                 break;
 289
 290         default:
 291                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 292                 return;
 293         }
 294
 295  out:
 296         ND_PRINT((ndo, ", length %u", length));
 297         return;
 298
 299 trunc:
 300         ND_PRINT((ndo, "%s", tstr));
 301 }
 302
 303 void
 304 arp_print(netdissect_options *ndo,
 305           const u_char *bp, u_int length, u_int caplen)
 306 {
 307         const struct arp_pkthdr *ap;
 308         u_short pro, hrd, op, linkaddr;
 309
 310         ap = (const struct arp_pkthdr *)bp;
 311         ND_TCHECK(*ap);
 312
 313         hrd = HRD(ap);
 314         pro = PRO(ap);
 315         op = OP(ap);
 316
 317
 318         /* if its ATM then call the ATM ARP printer
 319            for Frame-relay ARP most of the fields
 320            are similar to Ethernet so overload the Ethernet Printer
 321            and set the linkaddr type for linkaddr_string(ndo, ) accordingly */
 322
 323         switch(hrd) {
 324         case ARPHRD_ATM2225:
 325             atmarp_print(ndo, bp, length, caplen);
 326             return;
 327         case ARPHRD_FRELAY:
 328             linkaddr = LINKADDR_FRELAY;
 329             break;
 330         default:
 331             linkaddr = LINKADDR_ETHER;
 332             break;
 333         }
 334
 335         if (!ND_TTEST2(*ar_tpa(ap), PROTO_LEN(ap))) {
 336                 ND_PRINT((ndo, "%s", tstr));
 337                 ND_DEFAULTPRINT((const u_char *)ap, length);
 338                 return;
 339         }
 340
 341         if (!ndo->ndo_eflag) {
 342             ND_PRINT((ndo, "ARP, "));
 343         }
 344
 345         /* print hardware type/len and proto type/len */
 346         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
 347             PROTO_LEN(ap) != 4 ||
 348             HRD_LEN(ap) == 0 ||
 349             ndo->ndo_vflag) {
 350             ND_PRINT((ndo, "%s (len %u), %s (len %u)",
 351                       tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
 352                       HRD_LEN(ap),
 353                       tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
 354                       PROTO_LEN(ap)));
 355
 356             /* don't know know about the address formats */
 357             if (!ndo->ndo_vflag) {
 358                 goto out;
 359             }
 360         }
 361
 362         /* print operation */
 363         ND_PRINT((ndo, "%s%s ",
 364                ndo->ndo_vflag ? ", " : "",
 365                tok2str(arpop_values, "Unknown (%u)", op)));
 366
 367         switch (op) {
 368
 369         case ARPOP_REQUEST:
 370                 ND_PRINT((ndo, "who-has %s", ipaddr_string(ndo, TPA(ap))));
 371                 if (isnonzero((const u_char *)THA(ap), HRD_LEN(ap)))
 372                         ND_PRINT((ndo, " (%s)",
 373                                   linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap))));
 374                 ND_PRINT((ndo, " tell %s", ipaddr_string(ndo, SPA(ap))));
 375                 break;
 376
 377         case ARPOP_REPLY:
 378                 ND_PRINT((ndo, "%s is-at %s",
 379                           ipaddr_string(ndo, SPA(ap)),
 380                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
 381                 break;
 382
 383         case ARPOP_REVREQUEST:
 384                 ND_PRINT((ndo, "who-is %s tell %s",
 385                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
 386                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
 387                 break;
 388
 389         case ARPOP_REVREPLY:
 390                 ND_PRINT((ndo, "%s at %s",
 391                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
 392                           ipaddr_string(ndo, TPA(ap))));
 393                 break;
 394
 395         case ARPOP_INVREQUEST:
 396                 ND_PRINT((ndo, "who-is %s tell %s",
 397                           linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
 398                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
 399                 break;
 400
 401         case ARPOP_INVREPLY:
 402                 ND_PRINT((ndo,"%s at %s",
 403                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap)),
 404                           ipaddr_string(ndo, SPA(ap))));
 405                 break;
 406
 407         default:
 408                 ND_DEFAULTPRINT((const u_char *)ap, caplen);
 409                 return;
 410         }
 411
 412  out:
 413         ND_PRINT((ndo, ", length %u", length));
 414
 415         return;
 416 trunc:
 417         ND_PRINT((ndo, "%s", tstr));
 418 }
 419
 420 /*
 421  * Local Variables:
 422  * c-style: bsd
 423  * End:
 424  */
 425