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         int advance;
  52         u_int nh;
  53         const struct in6_addr *dst_addr;
  54         const struct ip6_rthdr *dp;
  55         const struct ip6_rthdr0 *dp0;
  56         const struct in6_addr *addr;
  57         int i, len;
  58
  59         cp = (const u_char *)ip6;
  60         advance = sizeof(struct ip6_hdr);
  61         nh = ip6->ip6_nxt;
  62         dst_addr = &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_TCHECK2(*cp, 2);
  80                         advance = (int)((*(cp + 1) + 1) << 3);
  81                         nh = *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_TCHECK2(*cp, 1);
  91                         advance = sizeof(struct ip6_frag);
  92                         nh = *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(*dp);
 101                         len = dp->ip6r_len;
 102                         switch (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                                 addr = &dp0->ip6r0_addr[0];
 111                                 for (i = 0; i < len; i++) {
 112                                         if ((const u_char *)(addr + 1) > ndo->ndo_snapend)
 113                                                 goto trunc;
 114
 115                                         dst_addr = addr;
 116                                         addr++;
 117                                 }
 118                                 break;
 119
 120                         default:
 121                                 break;
 122                         }
 123
 124                         /*
 125                          * Only one routing header to a customer.
 126                          */
 127                         goto done;
 128
 129                 case IPPROTO_AH:
 130                 case IPPROTO_ESP:
 131                 case IPPROTO_IPCOMP:
 132                 default:
 133                         /*
 134                          * AH and ESP are, in the RFCs that describe them,
 135                          * described as being "viewed as an end-to-end
 136                          * payload" "in the IPv6 context, so that they
 137                          * "should appear after hop-by-hop, routing, and
 138                          * fragmentation extension headers".  We assume
 139                          * that's the case, and stop as soon as we see
 140                          * one.  (We can't handle an ESP header in
 141                          * the general case anyway, as its length depends
 142                          * on the encryption algorithm.)
 143                          *
 144                          * IPComp is also "viewed as an end-to-end
 145                          * payload" "in the IPv6 context".
 146                          *
 147                          * All other protocols are assumed to be the final
 148                          * protocol.
 149                          */
 150                         goto done;
 151                 }
 152         }
 153
 154 done:
 155 trunc:
 156         UNALIGNED_MEMCPY(dst, dst_addr, sizeof(struct in6_addr));
 157 }
 158
 159 /*
 160  * Compute a V6-style checksum by building a pseudoheader.
 161  */
 162 int
 163 nextproto6_cksum(netdissect_options *ndo,
 164                  const struct ip6_hdr *ip6, const uint8_t *data,
 165                  u_int len, u_int covlen, u_int next_proto)
 166 {
 167         struct {
 168                 struct in6_addr ph_src;
 169                 struct in6_addr ph_dst;
 170                 uint32_t       ph_len;
 171                 uint8_t        ph_zero[3];
 172                 uint8_t        ph_nxt;
 173         } ph;
 174         struct cksum_vec vec[2];
 175
 176         /* pseudo-header */
 177         memset(&ph, 0, sizeof(ph));
 178         UNALIGNED_MEMCPY(&ph.ph_src, &ip6->ip6_src, sizeof (struct in6_addr));
 179         switch (ip6->ip6_nxt) {
 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, sizeof (struct in6_addr));
 197                 break;
 198         }
 199         ph.ph_len = htonl(len);
 200         ph.ph_nxt = next_proto;
 201
 202         vec[0].ptr = (const uint8_t *)(void *)&ph;
 203         vec[0].len = sizeof(ph);
 204         vec[1].ptr = data;
 205         vec[1].len = covlen;
 206
 207         return in_cksum(vec, 2);
 208 }
 209
 210 /*
 211  * print an IP6 datagram.
 212  */
 213 void
 214 ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
 215 {
 216         register const struct ip6_hdr *ip6;
 217         register int advance;
 218         u_int len;
 219         const u_char *ipend;
 220         register const u_char *cp;
 221         register u_int payload_len;
 222         int nh;
 223         int fragmented = 0;
 224         u_int flow;
 225
 226         ip6 = (const struct ip6_hdr *)bp;
 227
 228         ND_TCHECK(*ip6);
 229         if (length < sizeof (struct ip6_hdr)) {
 230                 ND_PRINT((ndo, "truncated-ip6 %u", length));
 231                 return;
 232         }
 233
 234         if (!ndo->ndo_eflag)
 235             ND_PRINT((ndo, "IP6 "));
 236
 237         if (IP6_VERSION(ip6) != 6) {
 238           ND_PRINT((ndo,"version error: %u != 6", IP6_VERSION(ip6)));
 239           return;
 240         }
 241
 242         payload_len = EXTRACT_16BITS(&ip6->ip6_plen);
 243         len = payload_len + sizeof(struct ip6_hdr);
 244         if (length < len)
 245                 ND_PRINT((ndo, "truncated-ip6 - %u bytes missing!",
 246                         len - length));
 247
 248         if (ndo->ndo_vflag) {
 249             flow = EXTRACT_32BITS(&ip6->ip6_flow);
 250             ND_PRINT((ndo, "("));
 251 #if 0
 252             /* rfc1883 */
 253             if (flow & 0x0f000000)
 254                 ND_PRINT((ndo, "pri 0x%02x, ", (flow & 0x0f000000) >> 24));
 255             if (flow & 0x00ffffff)
 256                 ND_PRINT((ndo, "flowlabel 0x%06x, ", flow & 0x00ffffff));
 257 #else
 258             /* RFC 2460 */
 259             if (flow & 0x0ff00000)
 260                 ND_PRINT((ndo, "class 0x%02x, ", (flow & 0x0ff00000) >> 20));
 261             if (flow & 0x000fffff)
 262                 ND_PRINT((ndo, "flowlabel 0x%05x, ", flow & 0x000fffff));
 263 #endif
 264
 265             ND_PRINT((ndo, "hlim %u, next-header %s (%u) payload length: %u) ",
 266                          ip6->ip6_hlim,
 267                          tok2str(ipproto_values,"unknown",ip6->ip6_nxt),
 268                          ip6->ip6_nxt,
 269                          payload_len));
 270         }
 271
 272         /*
 273          * Cut off the snapshot length to the end of the IP payload.
 274          */
 275         ipend = bp + len;
 276         if (ipend < ndo->ndo_snapend)
 277                 ndo->ndo_snapend = ipend;
 278
 279         cp = (const u_char *)ip6;
 280         advance = sizeof(struct ip6_hdr);
 281         nh = ip6->ip6_nxt;
 282         while (cp < ndo->ndo_snapend && advance > 0) {
 283                 cp += advance;
 284                 len -= advance;
 285
 286                 if (cp == (const u_char *)(ip6 + 1) &&
 287                     nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 288                     nh != IPPROTO_DCCP && nh != IPPROTO_SCTP) {
 289                         ND_PRINT((ndo, "%s > %s: ", ip6addr_string(ndo, &ip6->ip6_src),
 290                                      ip6addr_string(ndo, &ip6->ip6_dst)));
 291                 }
 292
 293                 switch (nh) {
 294                 case IPPROTO_HOPOPTS:
 295                         advance = hbhopt_print(ndo, cp);
 296                         if (advance < 0)
 297                                 return;
 298                         nh = *cp;
 299                         break;
 300                 case IPPROTO_DSTOPTS:
 301                         advance = dstopt_print(ndo, cp);
 302                         if (advance < 0)
 303                                 return;
 304                         nh = *cp;
 305                         break;
 306                 case IPPROTO_FRAGMENT:
 307                         advance = frag6_print(ndo, cp, (const u_char *)ip6);
 308                         if (advance < 0 || ndo->ndo_snapend <= cp + advance)
 309                                 return;
 310                         nh = *cp;
 311                         fragmented = 1;
 312                         break;
 313
 314                 case IPPROTO_MOBILITY_OLD:
 315                 case IPPROTO_MOBILITY:
 316                         /*
 317                          * XXX - we don't use "advance"; RFC 3775 says that
 318                          * the next header field in a mobility header
 319                          * should be IPPROTO_NONE, but speaks of
 320                          * the possiblity of a future extension in
 321                          * which payload can be piggybacked atop a
 322                          * mobility header.
 323                          */
 324                         advance = mobility_print(ndo, cp, (const u_char *)ip6);
 325                         nh = *cp;
 326                         return;
 327                 case IPPROTO_ROUTING:
 328                         advance = rt6_print(ndo, cp, (const u_char *)ip6);
 329                         nh = *cp;
 330                         break;
 331                 case IPPROTO_SCTP:
 332                         sctp_print(ndo, cp, (const u_char *)ip6, len);
 333                         return;
 334                 case IPPROTO_DCCP:
 335                         dccp_print(ndo, cp, (const u_char *)ip6, len);
 336                         return;
 337                 case IPPROTO_TCP:
 338                         tcp_print(ndo, cp, len, (const u_char *)ip6, fragmented);
 339                         return;
 340                 case IPPROTO_UDP:
 341                         udp_print(ndo, cp, len, (const u_char *)ip6, fragmented);
 342                         return;
 343                 case IPPROTO_ICMPV6:
 344                         icmp6_print(ndo, cp, len, (const u_char *)ip6, fragmented);
 345                         return;
 346                 case IPPROTO_AH:
 347                         advance = ah_print(ndo, cp);
 348                         nh = *cp;
 349                         break;
 350                 case IPPROTO_ESP:
 351                     {
 352                         int enh, padlen;
 353                         advance = esp_print(ndo, cp, len, (const u_char *)ip6, &enh, &padlen);
 354                         nh = enh & 0xff;
 355                         len -= padlen;
 356                         break;
 357                     }
 358                 case IPPROTO_IPCOMP:
 359                     {
 360                         ipcomp_print(ndo, cp);
 361                         /*
 362                          * Either this has decompressed the payload and
 363                          * printed it, in which case there's nothing more
 364                          * to do, or it hasn't, in which case there's
 365                          * nothing more to do.
 366                          */
 367                         advance = -1;
 368                         break;
 369                     }
 370
 371                 case IPPROTO_PIM:
 372                         pim_print(ndo, cp, len, (const u_char *)ip6);
 373                         return;
 374
 375                 case IPPROTO_OSPF:
 376                         ospf6_print(ndo, cp, len);
 377                         return;
 378
 379                 case IPPROTO_IPV6:
 380                         ip6_print(ndo, cp, len);
 381                         return;
 382
 383                 case IPPROTO_IPV4:
 384                         ip_print(ndo, cp, len);
 385                         return;
 386
 387                 case IPPROTO_PGM:
 388                         pgm_print(ndo, cp, len, (const u_char *)ip6);
 389                         return;
 390
 391                 case IPPROTO_GRE:
 392                         gre_print(ndo, cp, len);
 393                         return;
 394
 395                 case IPPROTO_RSVP:
 396                         rsvp_print(ndo, cp, len);
 397                         return;
 398
 399                 case IPPROTO_NONE:
 400                         ND_PRINT((ndo, "no next header"));
 401                         return;
 402
 403                 default:
 404                         ND_PRINT((ndo, "ip-proto-%d %d", nh, len));
 405                         return;
 406                 }
 407         }
 408
 409         return;
 410 trunc:
 411         ND_PRINT((ndo, "[|ip6]"));
 412 }