The Tcpdump Group git mirrors - tcpdump/blob - print-ip6.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994
   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: IPv6 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 "ip6.h"
  37 #include "ipproto.h"
  38
  39 /*
  40  * If routing headers are presend and valid, set dst to the final destination.
  41  * Otherwise, set it to the IPv6 destination.
  42  *
  43  * This is used for UDP and TCP pseudo-header in the checksum
  44  * calculation.
  45  */
  46 static void
  47 ip6_finddst(netdissect_options *ndo, struct in6_addr *dst,
  48             const struct ip6_hdr *ip6)
  49 {
  50         const u_char *cp;
  51         u_int advance;
  52         u_int nh;
  53         const void *dst_addr;
  54         const struct ip6_rthdr *dp;
  55         const struct ip6_rthdr0 *dp0;
  56         const u_char *p;
  57         int i, len;
  58
  59         cp = (const u_char *)ip6;
  60         advance = sizeof(struct ip6_hdr);
  61         nh = EXTRACT_U_1(ip6->ip6_nxt);
  62         dst_addr = (const void *)ip6->ip6_dst;
  63
  64         while (cp < ndo->ndo_snapend) {
  65                 cp += advance;
  66
  67                 switch (nh) {
  68
  69                 case IPPROTO_HOPOPTS:
  70                 case IPPROTO_DSTOPTS:
  71                 case IPPROTO_MOBILITY_OLD:
  72                 case IPPROTO_MOBILITY:
  73                         /*
  74                          * These have a header length byte, following
  75                          * the next header byte, giving the length of
  76                          * the header, in units of 8 octets, excluding
  77                          * the first 8 octets.
  78                          */
  79                         ND_TCHECK_2(cp);
  80                         advance = (EXTRACT_U_1(cp + 1) + 1) << 3;
  81                         nh = EXTRACT_U_1(cp);
  82                         break;
  83
  84                 case IPPROTO_FRAGMENT:
  85                         /*
  86                          * The byte following the next header byte is
  87                          * marked as reserved, and the header is always
  88                          * the same size.
  89                          */
  90                         ND_TCHECK_1(cp);
  91                         advance = sizeof(struct ip6_frag);
  92                         nh = EXTRACT_U_1(cp);
  93                         break;
  94
  95                 case IPPROTO_ROUTING:
  96                         /*
  97                          * OK, we found it.
  98                          */
  99                         dp = (const struct ip6_rthdr *)cp;
 100                         ND_TCHECK_SIZE(dp);
 101                         len = EXTRACT_U_1(dp->ip6r_len);
 102                         switch (EXTRACT_U_1(dp->ip6r_type)) {
 103
 104                         case IPV6_RTHDR_TYPE_0:
 105                         case IPV6_RTHDR_TYPE_2:         /* Mobile IPv6 ID-20 */
 106                                 dp0 = (const struct ip6_rthdr0 *)dp;
 107                                 if (len % 2 == 1)
 108                                         goto trunc;
 109                                 len >>= 1;
 110                                 p = (const u_char *) dp0->ip6r0_addr;
 111                                 for (i = 0; i < len; i++) {
 112                                         ND_TCHECK_16(p);
 113                                         dst_addr = (const void *)p;
 114                                         p += 16;
 115                                 }
 116                                 break;
 117
 118                         default:
 119                                 break;
 120                         }
 121
 122                         /*
 123                          * Only one routing header to a customer.
 124                          */
 125                         goto done;
 126
 127                 case IPPROTO_AH:
 128                 case IPPROTO_ESP:
 129                 case IPPROTO_IPCOMP:
 130                 default:
 131                         /*
 132                          * AH and ESP are, in the RFCs that describe them,
 133                          * described as being "viewed as an end-to-end
 134                          * payload" "in the IPv6 context, so that they
 135                          * "should appear after hop-by-hop, routing, and
 136                          * fragmentation extension headers".  We assume
 137                          * that's the case, and stop as soon as we see
 138                          * one.  (We can't handle an ESP header in
 139                          * the general case anyway, as its length depends
 140                          * on the encryption algorithm.)
 141                          *
 142                          * IPComp is also "viewed as an end-to-end
 143                          * payload" "in the IPv6 context".
 144                          *
 145                          * All other protocols are assumed to be the final
 146                          * protocol.
 147                          */
 148                         goto done;
 149                 }
 150         }
 151
 152 done:
 153 trunc:
 154         UNALIGNED_MEMCPY(dst, dst_addr, sizeof(nd_ipv6));
 155 }
 156
 157 /*
 158  * Compute a V6-style checksum by building a pseudoheader.
 159  */
 160 uint16_t
 161 nextproto6_cksum(netdissect_options *ndo,
 162                  const struct ip6_hdr *ip6, const uint8_t *data,
 163                  u_int len, u_int covlen, u_int next_proto)
 164 {
 165         struct {
 166                 struct in6_addr ph_src;
 167                 struct in6_addr ph_dst;
 168                 uint32_t       ph_len;
 169                 uint8_t        ph_zero[3];
 170                 uint8_t        ph_nxt;
 171         } ph;
 172         struct cksum_vec vec[2];
 173         u_int nh;
 174
 175         /* pseudo-header */
 176         memset(&ph, 0, sizeof(ph));
 177         UNALIGNED_MEMCPY(&ph.ph_src, ip6->ip6_src, sizeof (struct in6_addr));
 178         nh = EXTRACT_U_1(ip6->ip6_nxt);
 179         switch (nh) {
 180
 181         case IPPROTO_HOPOPTS:
 182         case IPPROTO_DSTOPTS:
 183         case IPPROTO_MOBILITY_OLD:
 184         case IPPROTO_MOBILITY:
 185         case IPPROTO_FRAGMENT:
 186         case IPPROTO_ROUTING:
 187                 /*
 188                  * The next header is either a routing header or a header
 189                  * after which there might be a routing header, so scan
 190                  * for a routing header.
 191                  */
 192                 ip6_finddst(ndo, &ph.ph_dst, ip6);
 193                 break;
 194
 195         default:
 196                 UNALIGNED_MEMCPY(&ph.ph_dst, ip6->ip6_dst,
 197                                  sizeof (struct in6_addr));
 198                 break;
 199         }
 200         ph.ph_len = htonl(len);
 201         ph.ph_nxt = next_proto;
 202
 203         vec[0].ptr = (const uint8_t *)(void *)&ph;
 204         vec[0].len = sizeof(ph);
 205         vec[1].ptr = data;
 206         vec[1].len = covlen;
 207
 208         return in_cksum(vec, 2);
 209 }
 210
 211 /*
 212  * print an IP6 datagram.
 213  */
 214 void
 215 ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
 216 {
 217         const struct ip6_hdr *ip6;
 218         int advance;
 219         u_int len;
 220         const u_char *ipend;
 221         const u_char *cp;
 222         u_int payload_len;
 223         u_int nh;
 224         int fragmented = 0;
 225         u_int flow;
 226
 227         ndo->ndo_protocol = "ip6";
 228         ip6 = (const struct ip6_hdr *)bp;
 229
 230         ND_TCHECK_SIZE(ip6);
 231         if (length < sizeof (struct ip6_hdr)) {
 232                 ND_PRINT("truncated-ip6 %u", length);
 233                 return;
 234         }
 235
 236         if (!ndo->ndo_eflag)
 237             ND_PRINT("IP6 ");
 238
 239         if (IP6_VERSION(ip6) != 6) {
 240           ND_PRINT("version error: %u != 6", IP6_VERSION(ip6));
 241           return;
 242         }
 243
 244         payload_len = EXTRACT_BE_U_2(ip6->ip6_plen);
 245         len = payload_len + sizeof(struct ip6_hdr);
 246         if (length < len)
 247                 ND_PRINT("truncated-ip6 - %u bytes missing!",
 248                         len - length);
 249
 250         nh = EXTRACT_U_1(ip6->ip6_nxt);
 251         if (ndo->ndo_vflag) {
 252             flow = EXTRACT_BE_U_4(ip6->ip6_flow);
 253             ND_PRINT("(");
 254 #if 0
 255             /* rfc1883 */
 256             if (flow & 0x0f000000)
 257                 ND_PRINT("pri 0x%02x, ", (flow & 0x0f000000) >> 24);
 258             if (flow & 0x00ffffff)
 259                 ND_PRINT("flowlabel 0x%06x, ", flow & 0x00ffffff);
 260 #else
 261             /* RFC 2460 */
 262             if (flow & 0x0ff00000)
 263                 ND_PRINT("class 0x%02x, ", (flow & 0x0ff00000) >> 20);
 264             if (flow & 0x000fffff)
 265                 ND_PRINT("flowlabel 0x%05x, ", flow & 0x000fffff);
 266 #endif
 267
 268             ND_PRINT("hlim %u, next-header %s (%u) payload length: %u) ",
 269                          EXTRACT_U_1(ip6->ip6_hlim),
 270                          tok2str(ipproto_values,"unknown",nh),
 271                          nh,
 272                          payload_len);
 273         }
 274
 275         /*
 276          * Cut off the snapshot length to the end of the IP payload.
 277          */
 278         ipend = bp + len;
 279         if (ipend < ndo->ndo_snapend)
 280                 ndo->ndo_snapend = ipend;
 281
 282         cp = (const u_char *)ip6;
 283         advance = sizeof(struct ip6_hdr);
 284         while (cp < ndo->ndo_snapend && advance > 0) {
 285                 if (len < (u_int)advance)
 286                         goto trunc;
 287                 cp += advance;
 288                 len -= advance;
 289
 290                 if (cp == (const u_char *)(ip6 + 1) &&
 291                     nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 292                     nh != IPPROTO_DCCP && nh != IPPROTO_SCTP) {
 293                         ND_PRINT("%s > %s: ", ip6addr_string(ndo, ip6->ip6_src),
 294                                      ip6addr_string(ndo, ip6->ip6_dst));
 295                 }
 296
 297                 switch (nh) {
 298                 case IPPROTO_HOPOPTS:
 299                         advance = hbhopt_print(ndo, cp);
 300                         if (advance < 0)
 301                                 return;
 302                         nh = EXTRACT_U_1(cp);
 303                         break;
 304                 case IPPROTO_DSTOPTS:
 305                         advance = dstopt_print(ndo, cp);
 306                         if (advance < 0)
 307                                 return;
 308                         nh = EXTRACT_U_1(cp);
 309                         break;
 310                 case IPPROTO_FRAGMENT:
 311                         advance = frag6_print(ndo, cp, (const u_char *)ip6);
 312                         if (advance < 0 || ndo->ndo_snapend <= cp + advance)
 313                                 return;
 314                         nh = EXTRACT_U_1(cp);
 315                         fragmented = 1;
 316                         break;
 317
 318                 case IPPROTO_MOBILITY_OLD:
 319                 case IPPROTO_MOBILITY:
 320                         /*
 321                          * XXX - we don't use "advance"; RFC 3775 says that
 322                          * the next header field in a mobility header
 323                          * should be IPPROTO_NONE, but speaks of
 324                          * the possiblity of a future extension in
 325                          * which payload can be piggybacked atop a
 326                          * mobility header.
 327                          */
 328                         advance = mobility_print(ndo, cp, (const u_char *)ip6);
 329                         if (advance < 0)
 330                                 return;
 331                         nh = EXTRACT_U_1(cp);
 332                         return;
 333                 case IPPROTO_ROUTING:
 334                         ND_TCHECK_1(cp);
 335                         advance = rt6_print(ndo, cp, (const u_char *)ip6);
 336                         if (advance < 0)
 337                                 return;
 338                         nh = EXTRACT_U_1(cp);
 339                         break;
 340                 case IPPROTO_SCTP:
 341                         sctp_print(ndo, cp, (const u_char *)ip6, len);
 342                         return;
 343                 case IPPROTO_DCCP:
 344                         dccp_print(ndo, cp, (const u_char *)ip6, len);
 345                         return;
 346                 case IPPROTO_TCP:
 347                         tcp_print(ndo, cp, len, (const u_char *)ip6, fragmented);
 348                         return;
 349                 case IPPROTO_UDP:
 350                         udp_print(ndo, cp, len, (const u_char *)ip6, fragmented);
 351                         return;
 352                 case IPPROTO_ICMPV6:
 353                         icmp6_print(ndo, cp, len, (const u_char *)ip6, fragmented);
 354                         return;
 355                 case IPPROTO_AH:
 356                         advance = ah_print(ndo, cp);
 357                         if (advance < 0)
 358                                 return;
 359                         nh = EXTRACT_U_1(cp);
 360                         break;
 361                 case IPPROTO_ESP:
 362                     {
 363                         u_int enh, padlen;
 364                         advance = esp_print(ndo, cp, len, (const u_char *)ip6, &enh, &padlen);
 365                         if (advance < 0)
 366                                 return;
 367                         nh = enh & 0xff;
 368                         len -= padlen;
 369                         break;
 370                     }
 371                 case IPPROTO_IPCOMP:
 372                     {
 373                         ipcomp_print(ndo, cp);
 374                         /*
 375                          * Either this has decompressed the payload and
 376                          * printed it, in which case there's nothing more
 377                          * to do, or it hasn't, in which case there's
 378                          * nothing more to do.
 379                          */
 380                         advance = -1;
 381                         break;
 382                     }
 383
 384                 case IPPROTO_PIM:
 385                         pim_print(ndo, cp, len, (const u_char *)ip6);
 386                         return;
 387
 388                 case IPPROTO_OSPF:
 389                         ospf6_print(ndo, cp, len);
 390                         return;
 391
 392                 case IPPROTO_IPV6:
 393                         ip6_print(ndo, cp, len);
 394                         return;
 395
 396                 case IPPROTO_IPV4:
 397                         ip_print(ndo, cp, len);
 398                         return;
 399
 400                 case IPPROTO_PGM:
 401                         pgm_print(ndo, cp, len, (const u_char *)ip6);
 402                         return;
 403
 404                 case IPPROTO_GRE:
 405                         gre_print(ndo, cp, len);
 406                         return;
 407
 408                 case IPPROTO_RSVP:
 409                         rsvp_print(ndo, cp, len);
 410                         return;
 411
 412                 case IPPROTO_EIGRP:
 413                         eigrp_print(ndo, cp, len);
 414                         return;
 415
 416                 case IPPROTO_NONE:
 417                         ND_PRINT("no next header");
 418                         return;
 419
 420                 default:
 421                         ND_PRINT("ip-proto-%u %u", nh, len);
 422                         return;
 423                 }
 424
 425                 /* ndo_protocol reassignment after xxx_print() calls */
 426                 ndo->ndo_protocol = "ip6";
 427         }
 428
 429         return;
 430 trunc:
 431         nd_print_trunc(ndo);
 432 }