The Tcpdump Group git mirrors - tcpdump/blob - print-ip.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: IP 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 "extract.h"
  35
  36 #include "ip.h"
  37 #include "ipproto.h"
  38
  39
  40 static const struct tok ip_option_values[] = {
  41     { IPOPT_EOL, "EOL" },
  42     { IPOPT_NOP, "NOP" },
  43     { IPOPT_TS, "timestamp" },
  44     { IPOPT_SECURITY, "security" },
  45     { IPOPT_RR, "RR" },
  46     { IPOPT_SSRR, "SSRR" },
  47     { IPOPT_LSRR, "LSRR" },
  48     { IPOPT_RA, "RA" },
  49     { IPOPT_RFC1393, "traceroute" },
  50     { 0, NULL }
  51 };
  52
  53 /*
  54  * print the recorded route in an IP RR, LSRR or SSRR option.
  55  */
  56 static int
  57 ip_printroute(netdissect_options *ndo,
  58               const u_char *cp, u_int length)
  59 {
  60         u_int ptr;
  61         u_int len;
  62
  63         if (length < 3) {
  64                 ND_PRINT(" [bad length %u]", length);
  65                 return (0);
  66         }
  67         if ((length + 1) & 3)
  68                 ND_PRINT(" [bad length %u]", length);
  69         ptr = GET_U_1(cp + 2) - 1;
  70         if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1)
  71                 ND_PRINT(" [bad ptr %u]", GET_U_1(cp + 2));
  72
  73         for (len = 3; len < length; len += 4) {
  74                 ND_PRINT(" %s", GET_IPADDR_STRING(cp + len));
  75                 if (ptr > len)
  76                         ND_PRINT(",");
  77         }
  78         return (0);
  79 }
  80
  81 /*
  82  * If source-routing is present and valid, return the final destination.
  83  * Otherwise, return IP destination.
  84  *
  85  * This is used for UDP and TCP pseudo-header in the checksum
  86  * calculation.
  87  */
  88 static uint32_t
  89 ip_finddst(netdissect_options *ndo,
  90            const struct ip *ip)
  91 {
  92         u_int length;
  93         u_int len;
  94         const u_char *cp;
  95
  96         cp = (const u_char *)(ip + 1);
  97         length = IP_HL(ip) * 4;
  98         if (length < sizeof(struct ip))
  99                 goto trunc;
 100         length -= sizeof(struct ip);
 101
 102         for (; length != 0; cp += len, length -= len) {
 103                 int tt;
 104
 105                 tt = GET_U_1(cp);
 106                 if (tt == IPOPT_EOL)
 107                         break;
 108                 else if (tt == IPOPT_NOP)
 109                         len = 1;
 110                 else {
 111                         len = GET_U_1(cp + 1);
 112                         if (len < 2)
 113                                 break;
 114                 }
 115                 if (length < len)
 116                         goto trunc;
 117                 ND_TCHECK_LEN(cp, len);
 118                 switch (tt) {
 119
 120                 case IPOPT_SSRR:
 121                 case IPOPT_LSRR:
 122                         if (len < 7)
 123                                 break;
 124                         return (GET_IPV4_TO_NETWORK_ORDER(cp + len - 4));
 125                 }
 126         }
 127 trunc:
 128         return (GET_IPV4_TO_NETWORK_ORDER(ip->ip_dst));
 129 }
 130
 131 /*
 132  * Compute a V4-style checksum by building a pseudoheader.
 133  */
 134 uint16_t
 135 nextproto4_cksum(netdissect_options *ndo,
 136                  const struct ip *ip, const uint8_t *data,
 137                  u_int len, u_int covlen, uint8_t next_proto)
 138 {
 139         struct phdr {
 140                 uint32_t src;
 141                 uint32_t dst;
 142                 uint8_t mbz;
 143                 uint8_t proto;
 144                 uint16_t len;
 145         } ph;
 146         struct cksum_vec vec[2];
 147
 148         /* pseudo-header.. */
 149         ph.len = htons((uint16_t)len);
 150         ph.mbz = 0;
 151         ph.proto = next_proto;
 152         ph.src = GET_IPV4_TO_NETWORK_ORDER(ip->ip_src);
 153         if (IP_HL(ip) == 5)
 154                 ph.dst = GET_IPV4_TO_NETWORK_ORDER(ip->ip_dst);
 155         else
 156                 ph.dst = ip_finddst(ndo, ip);
 157
 158         vec[0].ptr = (const uint8_t *)(void *)&ph;
 159         vec[0].len = sizeof(ph);
 160         vec[1].ptr = data;
 161         vec[1].len = covlen;
 162         return (in_cksum(vec, 2));
 163 }
 164
 165 static int
 166 ip_printts(netdissect_options *ndo,
 167            const u_char *cp, u_int length)
 168 {
 169         u_int ptr;
 170         u_int len;
 171         u_int hoplen;
 172         const char *type;
 173
 174         if (length < 4) {
 175                 ND_PRINT("[bad length %u]", length);
 176                 return (0);
 177         }
 178         ND_PRINT(" TS{");
 179         hoplen = ((GET_U_1(cp + 3) & 0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
 180         if ((length - 4) & (hoplen-1))
 181                 ND_PRINT("[bad length %u]", length);
 182         ptr = GET_U_1(cp + 2) - 1;
 183         len = 0;
 184         if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
 185                 ND_PRINT("[bad ptr %u]", GET_U_1(cp + 2));
 186         switch (GET_U_1(cp + 3)&0xF) {
 187         case IPOPT_TS_TSONLY:
 188                 ND_PRINT("TSONLY");
 189                 break;
 190         case IPOPT_TS_TSANDADDR:
 191                 ND_PRINT("TS+ADDR");
 192                 break;
 193         /*
 194          * prespecified should really be 3, but some ones might send 2
 195          * instead, and the IPOPT_TS_PRESPEC constant can apparently
 196          * have both values, so we have to hard-code it here.
 197          */
 198
 199         case 2:
 200                 ND_PRINT("PRESPEC2.0");
 201                 break;
 202         case 3:                 /* IPOPT_TS_PRESPEC */
 203                 ND_PRINT("PRESPEC");
 204                 break;
 205         default:
 206                 ND_PRINT("[bad ts type %u]", GET_U_1(cp + 3)&0xF);
 207                 goto done;
 208         }
 209
 210         type = " ";
 211         for (len = 4; len < length; len += hoplen) {
 212                 if (ptr == len)
 213                         type = " ^ ";
 214                 ND_TCHECK_LEN(cp + len, hoplen);
 215                 ND_PRINT("%s%u@%s", type, GET_BE_U_4(cp + len + hoplen - 4),
 216                           hoplen!=8 ? "" : GET_IPADDR_STRING(cp + len));
 217                 type = " ";
 218         }
 219
 220 done:
 221         ND_PRINT("%s", ptr == len ? " ^ " : "");
 222
 223         if (GET_U_1(cp + 3) >> 4)
 224                 ND_PRINT(" [%u hops not recorded]} ", GET_U_1(cp + 3)>>4);
 225         else
 226                 ND_PRINT("}");
 227         return (0);
 228
 229 trunc:
 230         return (-1);
 231 }
 232
 233 /*
 234  * print IP options.
 235    If truncated return -1, else 0.
 236  */
 237 static int
 238 ip_optprint(netdissect_options *ndo,
 239             const u_char *cp, u_int length)
 240 {
 241         u_int option_len;
 242         const char *sep = "";
 243
 244         for (; length > 0; cp += option_len, length -= option_len) {
 245                 u_int option_code;
 246
 247                 ND_PRINT("%s", sep);
 248                 sep = ",";
 249
 250                 option_code = GET_U_1(cp);
 251
 252                 ND_PRINT("%s",
 253                           tok2str(ip_option_values,"unknown %u",option_code));
 254
 255                 if (option_code == IPOPT_NOP ||
 256                     option_code == IPOPT_EOL)
 257                         option_len = 1;
 258
 259                 else {
 260                         option_len = GET_U_1(cp + 1);
 261                         if (option_len < 2) {
 262                                 ND_PRINT(" [bad length %u]", option_len);
 263                                 return 0;
 264                         }
 265                 }
 266
 267                 if (option_len > length) {
 268                         ND_PRINT(" [bad length %u]", option_len);
 269                         return 0;
 270                 }
 271
 272                 ND_TCHECK_LEN(cp, option_len);
 273
 274                 switch (option_code) {
 275                 case IPOPT_EOL:
 276                         return 0;
 277
 278                 case IPOPT_TS:
 279                         if (ip_printts(ndo, cp, option_len) == -1)
 280                                 goto trunc;
 281                         break;
 282
 283                 case IPOPT_RR:       /* fall through */
 284                 case IPOPT_SSRR:
 285                 case IPOPT_LSRR:
 286                         if (ip_printroute(ndo, cp, option_len) == -1)
 287                                 goto trunc;
 288                         break;
 289
 290                 case IPOPT_RA:
 291                         if (option_len < 4) {
 292                                 ND_PRINT(" [bad length %u]", option_len);
 293                                 break;
 294                         }
 295                         ND_TCHECK_1(cp + 3);
 296                         if (GET_BE_U_2(cp + 2) != 0)
 297                                 ND_PRINT(" value %u", GET_BE_U_2(cp + 2));
 298                         break;
 299
 300                 case IPOPT_NOP:       /* nothing to print - fall through */
 301                 case IPOPT_SECURITY:
 302                 default:
 303                         break;
 304                 }
 305         }
 306         return 0;
 307
 308 trunc:
 309         return -1;
 310 }
 311
 312 #define IP_RES 0x8000
 313
 314 static const struct tok ip_frag_values[] = {
 315         { IP_MF,        "+" },
 316         { IP_DF,        "DF" },
 317         { IP_RES,       "rsvd" }, /* The RFC3514 evil ;-) bit */
 318         { 0,            NULL }
 319 };
 320
 321
 322 /*
 323  * print an IP datagram.
 324  */
 325 void
 326 ip_print(netdissect_options *ndo,
 327          const u_char *bp,
 328          u_int length)
 329 {
 330         const struct ip *ip;
 331         u_int off;
 332         u_int hlen;
 333         u_int len;
 334         struct cksum_vec vec[1];
 335         uint8_t ip_tos, ip_ttl, ip_proto;
 336         uint16_t sum, ip_sum;
 337         const char *p_name;
 338         int truncated = 0;
 339
 340         ndo->ndo_protocol = "ip";
 341         ip = (const struct ip *)bp;
 342         if (IP_V(ip) != 4) { /* print version and fail if != 4 */
 343             if (IP_V(ip) == 6)
 344               ND_PRINT("IP6, wrong link-layer encapsulation");
 345             else
 346               ND_PRINT("IP%u", IP_V(ip));
 347             nd_print_invalid(ndo);
 348             return;
 349         }
 350         if (!ndo->ndo_eflag)
 351                 ND_PRINT("IP ");
 352
 353         ND_TCHECK_SIZE(ip);
 354         if (length < sizeof (struct ip)) {
 355                 ND_PRINT("truncated-ip %u", length);
 356                 return;
 357         }
 358         hlen = IP_HL(ip) * 4;
 359         if (hlen < sizeof (struct ip)) {
 360                 ND_PRINT("bad-hlen %u", hlen);
 361                 return;
 362         }
 363
 364         len = GET_BE_U_2(ip->ip_len);
 365         if (length < len)
 366                 ND_PRINT("truncated-ip - %u bytes missing! ",
 367                         len - length);
 368         if (len < hlen) {
 369 #ifdef GUESS_TSO
 370             if (len) {
 371                 ND_PRINT("bad-len %u", len);
 372                 return;
 373             }
 374             else {
 375                 /* we guess that it is a TSO send */
 376                 len = length;
 377             }
 378 #else
 379             ND_PRINT("bad-len %u", len);
 380             return;
 381 #endif /* GUESS_TSO */
 382         }
 383
 384         /*
 385          * Cut off the snapshot length to the end of the IP payload.
 386          */
 387         nd_push_snapend(ndo, bp + len);
 388
 389         len -= hlen;
 390
 391         off = GET_BE_U_2(ip->ip_off);
 392
 393         ip_proto = GET_U_1(ip->ip_p);
 394
 395         if (ndo->ndo_vflag) {
 396             ip_tos = GET_U_1(ip->ip_tos);
 397             ND_PRINT("(tos 0x%x", ip_tos);
 398             /* ECN bits */
 399             switch (ip_tos & 0x03) {
 400
 401             case 0:
 402                 break;
 403
 404             case 1:
 405                 ND_PRINT(",ECT(1)");
 406                 break;
 407
 408             case 2:
 409                 ND_PRINT(",ECT(0)");
 410                 break;
 411
 412             case 3:
 413                 ND_PRINT(",CE");
 414                 break;
 415             }
 416
 417             ip_ttl = GET_U_1(ip->ip_ttl);
 418             if (ip_ttl >= 1)
 419                 ND_PRINT(", ttl %u", ip_ttl);
 420
 421             /*
 422              * for the firewall guys, print id, offset.
 423              * On all but the last stick a "+" in the flags portion.
 424              * For unfragmented datagrams, note the don't fragment flag.
 425              */
 426             ND_PRINT(", id %u, offset %u, flags [%s], proto %s (%u)",
 427                          GET_BE_U_2(ip->ip_id),
 428                          (off & IP_OFFMASK) * 8,
 429                          bittok2str(ip_frag_values, "none", off & (IP_RES|IP_DF|IP_MF)),
 430                          tok2str(ipproto_values, "unknown", ip_proto),
 431                          ip_proto);
 432
 433             ND_PRINT(", length %u", GET_BE_U_2(ip->ip_len));
 434
 435             if ((hlen - sizeof(struct ip)) > 0) {
 436                 ND_PRINT(", options (");
 437                 if (ip_optprint(ndo, (const u_char *)(ip + 1),
 438                     hlen - sizeof(struct ip)) == -1) {
 439                         ND_PRINT(" [truncated-option]");
 440                         truncated = 1;
 441                 }
 442                 ND_PRINT(")");
 443             }
 444
 445             if (!ndo->ndo_Kflag && (const u_char *)ip + hlen <= ndo->ndo_snapend) {
 446                 vec[0].ptr = (const uint8_t *)(const void *)ip;
 447                 vec[0].len = hlen;
 448                 sum = in_cksum(vec, 1);
 449                 if (sum != 0) {
 450                     ip_sum = GET_BE_U_2(ip->ip_sum);
 451                     ND_PRINT(", bad cksum %x (->%x)!", ip_sum,
 452                              in_cksum_shouldbe(ip_sum, sum));
 453                 }
 454             }
 455
 456             ND_PRINT(")\n    ");
 457             if (truncated) {
 458                 ND_PRINT("%s > %s: ",
 459                          GET_IPADDR_STRING(ip->ip_src),
 460                          GET_IPADDR_STRING(ip->ip_dst));
 461                 nd_print_trunc(ndo);
 462                 nd_pop_packet_info(ndo);
 463                 return;
 464             }
 465         }
 466
 467         /*
 468          * If this is fragment zero, hand it to the next higher
 469          * level protocol.  Let them know whether there are more
 470          * fragments.
 471          */
 472         if ((off & IP_OFFMASK) == 0) {
 473                 uint8_t nh = GET_U_1(ip->ip_p);
 474
 475                 if (nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 476                     nh != IPPROTO_SCTP && nh != IPPROTO_DCCP) {
 477                         ND_PRINT("%s > %s: ",
 478                                      GET_IPADDR_STRING(ip->ip_src),
 479                                      GET_IPADDR_STRING(ip->ip_dst));
 480                 }
 481                 ip_demux_print(ndo, (const u_char *)ip + hlen, len, 4,
 482                     off & IP_MF, GET_U_1(ip->ip_ttl), nh, bp);
 483         } else {
 484                 /*
 485                  * Ultra quiet now means that all this stuff should be
 486                  * suppressed.
 487                  */
 488                 if (ndo->ndo_qflag > 1) {
 489                         nd_pop_packet_info(ndo);
 490                         return;
 491                 }
 492
 493                 /*
 494                  * This isn't the first frag, so we're missing the
 495                  * next level protocol header.  print the ip addr
 496                  * and the protocol.
 497                  */
 498                 ND_PRINT("%s > %s:", GET_IPADDR_STRING(ip->ip_src),
 499                           GET_IPADDR_STRING(ip->ip_dst));
 500                 if (!ndo->ndo_nflag && (p_name = netdb_protoname(ip_proto)) != NULL)
 501                         ND_PRINT(" %s", p_name);
 502                 else
 503                         ND_PRINT(" ip-proto-%u", ip_proto);
 504         }
 505         nd_pop_packet_info(ndo);
 506         return;
 507
 508 trunc:
 509         nd_print_trunc(ndo);
 510         return;
 511 }
 512
 513 void
 514 ipN_print(netdissect_options *ndo, const u_char *bp, u_int length)
 515 {
 516         ndo->ndo_protocol = "ipn";
 517         if (length < 1) {
 518                 ND_PRINT("truncated-ip %u", length);
 519                 return;
 520         }
 521
 522         switch (GET_U_1(bp) & 0xF0) {
 523         case 0x40:
 524                 ip_print(ndo, bp, length);
 525                 break;
 526         case 0x60:
 527                 ip6_print(ndo, bp, length);
 528                 break;
 529         default:
 530                 ND_PRINT("unknown ip %u", (GET_U_1(bp) & 0xF0) >> 4);
 531                 break;
 532         }
 533 }