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_TCHECK_4(cp + len);  /* Needed to print the IP addresses */
  75                 ND_PRINT(" %s", GET_IPADDR_STRING(cp + len));
  76                 if (ptr > len)
  77                         ND_PRINT(",");
  78         }
  79         return (0);
  80
  81 trunc:
  82         return (-1);
  83 }
  84
  85 /*
  86  * If source-routing is present and valid, return the final destination.
  87  * Otherwise, return IP destination.
  88  *
  89  * This is used for UDP and TCP pseudo-header in the checksum
  90  * calculation.
  91  */
  92 static uint32_t
  93 ip_finddst(netdissect_options *ndo,
  94            const struct ip *ip)
  95 {
  96         u_int length;
  97         u_int len;
  98         const u_char *cp;
  99
 100         cp = (const u_char *)(ip + 1);
 101         length = IP_HL(ip) * 4;
 102         if (length < sizeof(struct ip))
 103                 goto trunc;
 104         length -= sizeof(struct ip);
 105
 106         for (; length != 0; cp += len, length -= len) {
 107                 int tt;
 108
 109                 tt = GET_U_1(cp);
 110                 if (tt == IPOPT_EOL)
 111                         break;
 112                 else if (tt == IPOPT_NOP)
 113                         len = 1;
 114                 else {
 115                         len = GET_U_1(cp + 1);
 116                         if (len < 2)
 117                                 break;
 118                 }
 119                 if (length < len)
 120                         goto trunc;
 121                 ND_TCHECK_LEN(cp, len);
 122                 switch (tt) {
 123
 124                 case IPOPT_SSRR:
 125                 case IPOPT_LSRR:
 126                         if (len < 7)
 127                                 break;
 128                         return (GET_IPV4_TO_NETWORK_ORDER(cp + len - 4));
 129                 }
 130         }
 131 trunc:
 132         return (GET_IPV4_TO_NETWORK_ORDER(ip->ip_dst));
 133 }
 134
 135 /*
 136  * Compute a V4-style checksum by building a pseudoheader.
 137  */
 138 uint16_t
 139 nextproto4_cksum(netdissect_options *ndo,
 140                  const struct ip *ip, const uint8_t *data,
 141                  u_int len, u_int covlen, uint8_t next_proto)
 142 {
 143         struct phdr {
 144                 uint32_t src;
 145                 uint32_t dst;
 146                 uint8_t mbz;
 147                 uint8_t proto;
 148                 uint16_t len;
 149         } ph;
 150         struct cksum_vec vec[2];
 151
 152         /* pseudo-header.. */
 153         ph.len = htons((uint16_t)len);
 154         ph.mbz = 0;
 155         ph.proto = next_proto;
 156         ph.src = GET_IPV4_TO_NETWORK_ORDER(ip->ip_src);
 157         if (IP_HL(ip) == 5)
 158                 ph.dst = GET_IPV4_TO_NETWORK_ORDER(ip->ip_dst);
 159         else
 160                 ph.dst = ip_finddst(ndo, ip);
 161
 162         vec[0].ptr = (const uint8_t *)(void *)&ph;
 163         vec[0].len = sizeof(ph);
 164         vec[1].ptr = data;
 165         vec[1].len = covlen;
 166         return (in_cksum(vec, 2));
 167 }
 168
 169 static int
 170 ip_printts(netdissect_options *ndo,
 171            const u_char *cp, u_int length)
 172 {
 173         u_int ptr;
 174         u_int len;
 175         u_int hoplen;
 176         const char *type;
 177
 178         if (length < 4) {
 179                 ND_PRINT("[bad length %u]", length);
 180                 return (0);
 181         }
 182         ND_PRINT(" TS{");
 183         hoplen = ((GET_U_1(cp + 3) & 0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
 184         if ((length - 4) & (hoplen-1))
 185                 ND_PRINT("[bad length %u]", length);
 186         ptr = GET_U_1(cp + 2) - 1;
 187         len = 0;
 188         if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
 189                 ND_PRINT("[bad ptr %u]", GET_U_1(cp + 2));
 190         switch (GET_U_1(cp + 3)&0xF) {
 191         case IPOPT_TS_TSONLY:
 192                 ND_PRINT("TSONLY");
 193                 break;
 194         case IPOPT_TS_TSANDADDR:
 195                 ND_PRINT("TS+ADDR");
 196                 break;
 197         case IPOPT_TS_PRESPEC:
 198                 ND_PRINT("PRESPEC");
 199                 break;
 200         default:
 201                 ND_PRINT("[bad ts type %u]", GET_U_1(cp + 3)&0xF);
 202                 goto done;
 203         }
 204
 205         type = " ";
 206         for (len = 4; len < length; len += hoplen) {
 207                 if (ptr == len)
 208                         type = " ^ ";
 209                 ND_TCHECK_LEN(cp + len, hoplen);
 210                 ND_PRINT("%s%u@%s", type, GET_BE_U_4(cp + len + hoplen - 4),
 211                           hoplen!=8 ? "" : GET_IPADDR_STRING(cp + len));
 212                 type = " ";
 213         }
 214
 215 done:
 216         ND_PRINT("%s", ptr == len ? " ^ " : "");
 217
 218         if (GET_U_1(cp + 3) >> 4)
 219                 ND_PRINT(" [%u hops not recorded]} ", GET_U_1(cp + 3)>>4);
 220         else
 221                 ND_PRINT("}");
 222         return (0);
 223
 224 trunc:
 225         return (-1);
 226 }
 227
 228 /*
 229  * print IP options.
 230    If truncated return -1, else 0.
 231  */
 232 static int
 233 ip_optprint(netdissect_options *ndo,
 234             const u_char *cp, u_int length)
 235 {
 236         u_int option_len;
 237         const char *sep = "";
 238
 239         for (; length > 0; cp += option_len, length -= option_len) {
 240                 u_int option_code;
 241
 242                 ND_PRINT("%s", sep);
 243                 sep = ",";
 244
 245                 option_code = GET_U_1(cp);
 246
 247                 ND_PRINT("%s",
 248                           tok2str(ip_option_values,"unknown %u",option_code));
 249
 250                 if (option_code == IPOPT_NOP ||
 251                     option_code == IPOPT_EOL)
 252                         option_len = 1;
 253
 254                 else {
 255                         option_len = GET_U_1(cp + 1);
 256                         if (option_len < 2) {
 257                                 ND_PRINT(" [bad length %u]", option_len);
 258                                 return 0;
 259                         }
 260                 }
 261
 262                 if (option_len > length) {
 263                         ND_PRINT(" [bad length %u]", option_len);
 264                         return 0;
 265                 }
 266
 267                 ND_TCHECK_LEN(cp, option_len);
 268
 269                 switch (option_code) {
 270                 case IPOPT_EOL:
 271                         return 0;
 272
 273                 case IPOPT_TS:
 274                         if (ip_printts(ndo, cp, option_len) == -1)
 275                                 goto trunc;
 276                         break;
 277
 278                 case IPOPT_RR:       /* fall through */
 279                 case IPOPT_SSRR:
 280                 case IPOPT_LSRR:
 281                         if (ip_printroute(ndo, cp, option_len) == -1)
 282                                 goto trunc;
 283                         break;
 284
 285                 case IPOPT_RA:
 286                         if (option_len < 4) {
 287                                 ND_PRINT(" [bad length %u]", option_len);
 288                                 break;
 289                         }
 290                         ND_TCHECK_1(cp + 3);
 291                         if (GET_BE_U_2(cp + 2) != 0)
 292                                 ND_PRINT(" value %u", GET_BE_U_2(cp + 2));
 293                         break;
 294
 295                 case IPOPT_NOP:       /* nothing to print - fall through */
 296                 case IPOPT_SECURITY:
 297                 default:
 298                         break;
 299                 }
 300         }
 301         return 0;
 302
 303 trunc:
 304         return -1;
 305 }
 306
 307 #define IP_RES 0x8000
 308
 309 static const struct tok ip_frag_values[] = {
 310         { IP_MF,        "+" },
 311         { IP_DF,        "DF" },
 312         { IP_RES,       "rsvd" }, /* The RFC3514 evil ;-) bit */
 313         { 0,            NULL }
 314 };
 315
 316
 317 /*
 318  * print an IP datagram.
 319  */
 320 void
 321 ip_print(netdissect_options *ndo,
 322          const u_char *bp,
 323          u_int length)
 324 {
 325         const struct ip *ip;
 326         u_int off;
 327         u_int hlen;
 328         u_int len;
 329         struct cksum_vec vec[1];
 330         uint8_t ip_tos, ip_ttl, ip_proto;
 331         uint16_t sum, ip_sum;
 332         const char *p_name;
 333         int truncated = 0;
 334
 335         ndo->ndo_protocol = "ip";
 336         ip = (const struct ip *)bp;
 337         if (IP_V(ip) != 4) { /* print version and fail if != 4 */
 338             if (IP_V(ip) == 6)
 339               ND_PRINT("IP6, wrong link-layer encapsulation");
 340             else
 341               ND_PRINT("IP%u", IP_V(ip));
 342             nd_print_invalid(ndo);
 343             return;
 344         }
 345         if (!ndo->ndo_eflag)
 346                 ND_PRINT("IP ");
 347
 348         ND_TCHECK_SIZE(ip);
 349         if (length < sizeof (struct ip)) {
 350                 ND_PRINT("truncated-ip %u", length);
 351                 return;
 352         }
 353         hlen = IP_HL(ip) * 4;
 354         if (hlen < sizeof (struct ip)) {
 355                 ND_PRINT("bad-hlen %u", hlen);
 356                 return;
 357         }
 358
 359         len = GET_BE_U_2(ip->ip_len);
 360         if (length < len)
 361                 ND_PRINT("truncated-ip - %u bytes missing! ",
 362                         len - length);
 363         if (len < hlen) {
 364 #ifdef GUESS_TSO
 365             if (len) {
 366                 ND_PRINT("bad-len %u", len);
 367                 return;
 368             }
 369             else {
 370                 /* we guess that it is a TSO send */
 371                 len = length;
 372             }
 373 #else
 374             ND_PRINT("bad-len %u", len);
 375             return;
 376 #endif /* GUESS_TSO */
 377         }
 378
 379         /*
 380          * Cut off the snapshot length to the end of the IP payload.
 381          */
 382         nd_push_snapend(ndo, bp + len);
 383
 384         len -= hlen;
 385
 386         off = GET_BE_U_2(ip->ip_off);
 387
 388         ip_proto = GET_U_1(ip->ip_p);
 389
 390         if (ndo->ndo_vflag) {
 391             ip_tos = GET_U_1(ip->ip_tos);
 392             ND_PRINT("(tos 0x%x", ip_tos);
 393             /* ECN bits */
 394             switch (ip_tos & 0x03) {
 395
 396             case 0:
 397                 break;
 398
 399             case 1:
 400                 ND_PRINT(",ECT(1)");
 401                 break;
 402
 403             case 2:
 404                 ND_PRINT(",ECT(0)");
 405                 break;
 406
 407             case 3:
 408                 ND_PRINT(",CE");
 409                 break;
 410             }
 411
 412             ip_ttl = GET_U_1(ip->ip_ttl);
 413             if (ip_ttl >= 1)
 414                 ND_PRINT(", ttl %u", ip_ttl);
 415
 416             /*
 417              * for the firewall guys, print id, offset.
 418              * On all but the last stick a "+" in the flags portion.
 419              * For unfragmented datagrams, note the don't fragment flag.
 420              */
 421             ND_PRINT(", id %u, offset %u, flags [%s], proto %s (%u)",
 422                          GET_BE_U_2(ip->ip_id),
 423                          (off & IP_OFFMASK) * 8,
 424                          bittok2str(ip_frag_values, "none", off & (IP_RES|IP_DF|IP_MF)),
 425                          tok2str(ipproto_values, "unknown", ip_proto),
 426                          ip_proto);
 427
 428             ND_PRINT(", length %u", GET_BE_U_2(ip->ip_len));
 429
 430             if ((hlen - sizeof(struct ip)) > 0) {
 431                 ND_PRINT(", options (");
 432                 if (ip_optprint(ndo, (const u_char *)(ip + 1),
 433                     hlen - sizeof(struct ip)) == -1) {
 434                         ND_PRINT(" [truncated-option]");
 435                         truncated = 1;
 436                 }
 437                 ND_PRINT(")");
 438             }
 439
 440             if (!ndo->ndo_Kflag && (const u_char *)ip + hlen <= ndo->ndo_snapend) {
 441                 vec[0].ptr = (const uint8_t *)(const void *)ip;
 442                 vec[0].len = hlen;
 443                 sum = in_cksum(vec, 1);
 444                 if (sum != 0) {
 445                     ip_sum = GET_BE_U_2(ip->ip_sum);
 446                     ND_PRINT(", bad cksum %x (->%x)!", ip_sum,
 447                              in_cksum_shouldbe(ip_sum, sum));
 448                 }
 449             }
 450
 451             ND_PRINT(")\n    ");
 452             if (truncated) {
 453                 ND_PRINT("%s > %s: ",
 454                          GET_IPADDR_STRING(ip->ip_src),
 455                          GET_IPADDR_STRING(ip->ip_dst));
 456                 nd_print_trunc(ndo);
 457                 nd_pop_packet_info(ndo);
 458                 return;
 459             }
 460         }
 461
 462         /*
 463          * If this is fragment zero, hand it to the next higher
 464          * level protocol.  Let them know whether there are more
 465          * fragments.
 466          */
 467         if ((off & IP_OFFMASK) == 0) {
 468                 uint8_t nh = GET_U_1(ip->ip_p);
 469
 470                 if (nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 471                     nh != IPPROTO_SCTP && nh != IPPROTO_DCCP) {
 472                         ND_PRINT("%s > %s: ",
 473                                      GET_IPADDR_STRING(ip->ip_src),
 474                                      GET_IPADDR_STRING(ip->ip_dst));
 475                 }
 476                 ip_demux_print(ndo, (const u_char *)ip + hlen, len, 4,
 477                     off & IP_MF, GET_U_1(ip->ip_ttl), nh, bp);
 478         } else {
 479                 /*
 480                  * Ultra quiet now means that all this stuff should be
 481                  * suppressed.
 482                  */
 483                 if (ndo->ndo_qflag > 1) {
 484                         nd_pop_packet_info(ndo);
 485                         return;
 486                 }
 487
 488                 /*
 489                  * This isn't the first frag, so we're missing the
 490                  * next level protocol header.  print the ip addr
 491                  * and the protocol.
 492                  */
 493                 ND_PRINT("%s > %s:", GET_IPADDR_STRING(ip->ip_src),
 494                           GET_IPADDR_STRING(ip->ip_dst));
 495                 if (!ndo->ndo_nflag && (p_name = netdb_protoname(ip_proto)) != NULL)
 496                         ND_PRINT(" %s", p_name);
 497                 else
 498                         ND_PRINT(" ip-proto-%u", ip_proto);
 499         }
 500         nd_pop_packet_info(ndo);
 501         return;
 502
 503 trunc:
 504         nd_print_trunc(ndo);
 505         return;
 506 }
 507
 508 void
 509 ipN_print(netdissect_options *ndo, const u_char *bp, u_int length)
 510 {
 511         ndo->ndo_protocol = "ipn";
 512         if (length < 1) {
 513                 ND_PRINT("truncated-ip %u", length);
 514                 return;
 515         }
 516
 517         switch (GET_U_1(bp) & 0xF0) {
 518         case 0x40:
 519                 ip_print(ndo, bp, length);
 520                 break;
 521         case 0x60:
 522                 ip6_print(ndo, bp, length);
 523                 break;
 524         default:
 525                 ND_PRINT("unknown ip %u", (GET_U_1(bp) & 0xF0) >> 4);
 526                 break;
 527         }
 528 }