print-icmp.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1993, 1994, 1995, 1996
   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 #ifndef lint
  23 static const char rcsid[] _U_ =
  24     "@(#) $Header: /tcpdump/master/tcpdump/print-icmp.c,v 1.87 2007-09-13 17:42:31 guy Exp $ (LBL)";
  25 #endif
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <tcpdump-stdinc.h>
  32
  33 #include <stdio.h>
  34 #include <string.h>
  35
  36 #include "interface.h"
  37 #include "addrtoname.h"
  38 #include "extract.h"                    /* must come after interface.h */
  39
  40 #include "ip.h"
  41 #include "udp.h"
  42 #include "ipproto.h"
  43 #include "mpls.h"
  44
  45 /*
  46  * Interface Control Message Protocol Definitions.
  47  * Per RFC 792, September 1981.
  48  */
  49
  50 /*
  51  * Structure of an icmp header.
  52  */
  53 struct icmp {
  54         u_int8_t  icmp_type;            /* type of message, see below */
  55         u_int8_t  icmp_code;            /* type sub code */
  56         u_int16_t icmp_cksum;           /* ones complement cksum of struct */
  57         union {
  58                 u_int8_t ih_pptr;                       /* ICMP_PARAMPROB */
  59                 struct in_addr ih_gwaddr;       /* ICMP_REDIRECT */
  60                 struct ih_idseq {
  61                         u_int16_t icd_id;
  62                         u_int16_t icd_seq;
  63                 } ih_idseq;
  64                 u_int32_t ih_void;
  65         } icmp_hun;
  66 #define icmp_pptr       icmp_hun.ih_pptr
  67 #define icmp_gwaddr     icmp_hun.ih_gwaddr
  68 #define icmp_id         icmp_hun.ih_idseq.icd_id
  69 #define icmp_seq        icmp_hun.ih_idseq.icd_seq
  70 #define icmp_void       icmp_hun.ih_void
  71         union {
  72                 struct id_ts {
  73                         u_int32_t its_otime;
  74                         u_int32_t its_rtime;
  75                         u_int32_t its_ttime;
  76                 } id_ts;
  77                 struct id_ip  {
  78                         struct ip idi_ip;
  79                         /* options and then 64 bits of data */
  80                 } id_ip;
  81                 u_int32_t id_mask;
  82                 u_int8_t id_data[1];
  83         } icmp_dun;
  84 #define icmp_otime      icmp_dun.id_ts.its_otime
  85 #define icmp_rtime      icmp_dun.id_ts.its_rtime
  86 #define icmp_ttime      icmp_dun.id_ts.its_ttime
  87 #define icmp_ip         icmp_dun.id_ip.idi_ip
  88 #define icmp_mask       icmp_dun.id_mask
  89 #define icmp_data       icmp_dun.id_data
  90 };
  91
  92 #define ICMP_MPLS_EXT_EXTRACT_VERSION(x) (((x)&0xf0)>>4)
  93 #define ICMP_MPLS_EXT_VERSION 2
  94
  95 /*
  96  * Lower bounds on packet lengths for various types.
  97  * For the error advice packets must first insure that the
  98  * packet is large enought to contain the returned ip header.
  99  * Only then can we do the check to see if 64 bits of packet
 100  * data have been returned, since we need to check the returned
 101  * ip header length.
 102  */
 103 #define ICMP_MINLEN     8                               /* abs minimum */
 104 #define ICMP_EXTD_MINLEN (156 - sizeof (struct ip))     /* draft-bonica-internet-icmp-08 */
 105 #define ICMP_TSLEN      (8 + 3 * sizeof (u_int32_t))    /* timestamp */
 106 #define ICMP_MASKLEN    12                              /* address mask */
 107 #define ICMP_ADVLENMIN  (8 + sizeof (struct ip) + 8)    /* min */
 108 #define ICMP_ADVLEN(p)  (8 + (IP_HL(&(p)->icmp_ip) << 2) + 8)
 109         /* N.B.: must separately check that ip_hl >= 5 */
 110
 111 /*
 112  * Definition of type and code field values.
 113  */
 114 #define ICMP_ECHOREPLY          0               /* echo reply */
 115 #define ICMP_UNREACH            3               /* dest unreachable, codes: */
 116 #define         ICMP_UNREACH_NET        0               /* bad net */
 117 #define         ICMP_UNREACH_HOST       1               /* bad host */
 118 #define         ICMP_UNREACH_PROTOCOL   2               /* bad protocol */
 119 #define         ICMP_UNREACH_PORT       3               /* bad port */
 120 #define         ICMP_UNREACH_NEEDFRAG   4               /* IP_DF caused drop */
 121 #define         ICMP_UNREACH_SRCFAIL    5               /* src route failed */
 122 #define         ICMP_UNREACH_NET_UNKNOWN 6              /* unknown net */
 123 #define         ICMP_UNREACH_HOST_UNKNOWN 7             /* unknown host */
 124 #define         ICMP_UNREACH_ISOLATED   8               /* src host isolated */
 125 #define         ICMP_UNREACH_NET_PROHIB 9               /* prohibited access */
 126 #define         ICMP_UNREACH_HOST_PROHIB 10             /* ditto */
 127 #define         ICMP_UNREACH_TOSNET     11              /* bad tos for net */
 128 #define         ICMP_UNREACH_TOSHOST    12              /* bad tos for host */
 129 #define ICMP_SOURCEQUENCH       4               /* packet lost, slow down */
 130 #define ICMP_REDIRECT           5               /* shorter route, codes: */
 131 #define         ICMP_REDIRECT_NET       0               /* for network */
 132 #define         ICMP_REDIRECT_HOST      1               /* for host */
 133 #define         ICMP_REDIRECT_TOSNET    2               /* for tos and net */
 134 #define         ICMP_REDIRECT_TOSHOST   3               /* for tos and host */
 135 #define ICMP_ECHO               8               /* echo service */
 136 #define ICMP_ROUTERADVERT       9               /* router advertisement */
 137 #define ICMP_ROUTERSOLICIT      10              /* router solicitation */
 138 #define ICMP_TIMXCEED           11              /* time exceeded, code: */
 139 #define         ICMP_TIMXCEED_INTRANS   0               /* ttl==0 in transit */
 140 #define         ICMP_TIMXCEED_REASS     1               /* ttl==0 in reass */
 141 #define ICMP_PARAMPROB          12              /* ip header bad */
 142 #define         ICMP_PARAMPROB_OPTABSENT 1              /* req. opt. absent */
 143 #define ICMP_TSTAMP             13              /* timestamp request */
 144 #define ICMP_TSTAMPREPLY        14              /* timestamp reply */
 145 #define ICMP_IREQ               15              /* information request */
 146 #define ICMP_IREQREPLY          16              /* information reply */
 147 #define ICMP_MASKREQ            17              /* address mask request */
 148 #define ICMP_MASKREPLY          18              /* address mask reply */
 149
 150 #define ICMP_MAXTYPE            18
 151
 152 #define ICMP_INFOTYPE(type) \
 153         ((type) == ICMP_ECHOREPLY || (type) == ICMP_ECHO || \
 154         (type) == ICMP_ROUTERADVERT || (type) == ICMP_ROUTERSOLICIT || \
 155         (type) == ICMP_TSTAMP || (type) == ICMP_TSTAMPREPLY || \
 156         (type) == ICMP_IREQ || (type) == ICMP_IREQREPLY || \
 157         (type) == ICMP_MASKREQ || (type) == ICMP_MASKREPLY)
 158 #define ICMP_MPLS_EXT_TYPE(type) \
 159         ((type) == ICMP_UNREACH || \
 160          (type) == ICMP_TIMXCEED || \
 161          (type) == ICMP_PARAMPROB)
 162 /* rfc1700 */
 163 #ifndef ICMP_UNREACH_NET_UNKNOWN
 164 #define ICMP_UNREACH_NET_UNKNOWN        6       /* destination net unknown */
 165 #endif
 166 #ifndef ICMP_UNREACH_HOST_UNKNOWN
 167 #define ICMP_UNREACH_HOST_UNKNOWN       7       /* destination host unknown */
 168 #endif
 169 #ifndef ICMP_UNREACH_ISOLATED
 170 #define ICMP_UNREACH_ISOLATED           8       /* source host isolated */
 171 #endif
 172 #ifndef ICMP_UNREACH_NET_PROHIB
 173 #define ICMP_UNREACH_NET_PROHIB         9       /* admin prohibited net */
 174 #endif
 175 #ifndef ICMP_UNREACH_HOST_PROHIB
 176 #define ICMP_UNREACH_HOST_PROHIB        10      /* admin prohibited host */
 177 #endif
 178 #ifndef ICMP_UNREACH_TOSNET
 179 #define ICMP_UNREACH_TOSNET             11      /* tos prohibited net */
 180 #endif
 181 #ifndef ICMP_UNREACH_TOSHOST
 182 #define ICMP_UNREACH_TOSHOST            12      /* tos prohibited host */
 183 #endif
 184
 185 /* rfc1716 */
 186 #ifndef ICMP_UNREACH_FILTER_PROHIB
 187 #define ICMP_UNREACH_FILTER_PROHIB      13      /* admin prohibited filter */
 188 #endif
 189 #ifndef ICMP_UNREACH_HOST_PRECEDENCE
 190 #define ICMP_UNREACH_HOST_PRECEDENCE    14      /* host precedence violation */
 191 #endif
 192 #ifndef ICMP_UNREACH_PRECEDENCE_CUTOFF
 193 #define ICMP_UNREACH_PRECEDENCE_CUTOFF  15      /* precedence cutoff */
 194 #endif
 195
 196 /* Most of the icmp types */
 197 static struct tok icmp2str[] = {
 198         { ICMP_ECHOREPLY,               "echo reply" },
 199         { ICMP_SOURCEQUENCH,            "source quench" },
 200         { ICMP_ECHO,                    "echo request" },
 201         { ICMP_ROUTERSOLICIT,           "router solicitation" },
 202         { ICMP_TSTAMP,                  "time stamp request" },
 203         { ICMP_TSTAMPREPLY,             "time stamp reply" },
 204         { ICMP_IREQ,                    "information request" },
 205         { ICMP_IREQREPLY,               "information reply" },
 206         { ICMP_MASKREQ,                 "address mask request" },
 207         { 0,                            NULL }
 208 };
 209
 210 /* Formats for most of the ICMP_UNREACH codes */
 211 static struct tok unreach2str[] = {
 212         { ICMP_UNREACH_NET,             "net %s unreachable" },
 213         { ICMP_UNREACH_HOST,            "host %s unreachable" },
 214         { ICMP_UNREACH_SRCFAIL,
 215             "%s unreachable - source route failed" },
 216         { ICMP_UNREACH_NET_UNKNOWN,     "net %s unreachable - unknown" },
 217         { ICMP_UNREACH_HOST_UNKNOWN,    "host %s unreachable - unknown" },
 218         { ICMP_UNREACH_ISOLATED,
 219             "%s unreachable - source host isolated" },
 220         { ICMP_UNREACH_NET_PROHIB,
 221             "net %s unreachable - admin prohibited" },
 222         { ICMP_UNREACH_HOST_PROHIB,
 223             "host %s unreachable - admin prohibited" },
 224         { ICMP_UNREACH_TOSNET,
 225             "net %s unreachable - tos prohibited" },
 226         { ICMP_UNREACH_TOSHOST,
 227             "host %s unreachable - tos prohibited" },
 228         { ICMP_UNREACH_FILTER_PROHIB,
 229             "host %s unreachable - admin prohibited filter" },
 230         { ICMP_UNREACH_HOST_PRECEDENCE,
 231             "host %s unreachable - host precedence violation" },
 232         { ICMP_UNREACH_PRECEDENCE_CUTOFF,
 233             "host %s unreachable - precedence cutoff" },
 234         { 0,                            NULL }
 235 };
 236
 237 /* Formats for the ICMP_REDIRECT codes */
 238 static struct tok type2str[] = {
 239         { ICMP_REDIRECT_NET,            "redirect %s to net %s" },
 240         { ICMP_REDIRECT_HOST,           "redirect %s to host %s" },
 241         { ICMP_REDIRECT_TOSNET,         "redirect-tos %s to net %s" },
 242         { ICMP_REDIRECT_TOSHOST,        "redirect-tos %s to host %s" },
 243         { 0,                            NULL }
 244 };
 245
 246 /* rfc1191 */
 247 struct mtu_discovery {
 248         u_int16_t unused;
 249         u_int16_t nexthopmtu;
 250 };
 251
 252 /* rfc1256 */
 253 struct ih_rdiscovery {
 254         u_int8_t ird_addrnum;
 255         u_int8_t ird_addrsiz;
 256         u_int16_t ird_lifetime;
 257 };
 258
 259 struct id_rdiscovery {
 260         u_int32_t ird_addr;
 261         u_int32_t ird_pref;
 262 };
 263
 264 /*
 265  * draft-bonica-internet-icmp-08
 266  *
 267  * The Destination Unreachable, Time Exceeded
 268  * and Parameter Problem messages are slighly changed as per
 269  * the above draft. A new Length field gets added to give
 270  * the caller an idea about the length of the piggypacked
 271  * IP packet before the MPLS extension header starts.
 272  *
 273  * The Length field represents length of the padded "original datagram"
 274  * field  measured in 32-bit words.
 275  *
 276  * 0                   1                   2                   3
 277  * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 278  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 279  * |     Type      |     Code      |          Checksum             |
 280  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 281  * |     unused    |    Length     |          unused               |
 282  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 283  * |      Internet Header + leading octets of original datagram    |
 284  * |                                                               |
 285  * |                           //                                  |
 286  * |                                                               |
 287  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 288  */
 289
 290 struct icmp_ext_t {
 291     u_int8_t icmp_type;
 292     u_int8_t icmp_code;
 293     u_int8_t icmp_checksum[2];
 294     u_int8_t icmp_reserved;
 295     u_int8_t icmp_length;
 296     u_int8_t icmp_reserved2[2];
 297     u_int8_t icmp_ext_legacy_header[128]; /* extension header starts 128 bytes after ICMP header */
 298     u_int8_t icmp_ext_version_res[2];
 299     u_int8_t icmp_ext_checksum[2];
 300     u_int8_t icmp_ext_data[1];
 301 };
 302
 303 struct icmp_mpls_ext_object_header_t {
 304     u_int8_t length[2];
 305     u_int8_t class_num;
 306     u_int8_t ctype;
 307 };
 308
 309 static const struct tok icmp_mpls_ext_obj_values[] = {
 310     { 1, "MPLS Stack Entry" },
 311     { 2, "Extended Payload" },
 312     { 0, NULL}
 313 };
 314
 315 /* prototypes */
 316 const char *icmp_tstamp_print(u_int);
 317
 318 /* print the milliseconds since midnight UTC */
 319 const char *
 320 icmp_tstamp_print(u_int tstamp) {
 321     u_int msec,sec,min,hrs;
 322
 323     static char buf[64];
 324
 325     msec = tstamp % 1000;
 326     sec = tstamp / 1000;
 327     min = sec / 60; sec -= min * 60;
 328     hrs = min / 60; min -= hrs * 60;
 329     snprintf(buf, sizeof(buf), "%02u:%02u:%02u.%03u",hrs,min,sec,msec);
 330     return buf;
 331 }
 332
 333 void
 334 icmp_print(const u_char *bp, u_int plen, const u_char *bp2, int fragmented)
 335 {
 336         char *cp;
 337         const struct icmp *dp;
 338         const struct icmp_ext_t *ext_dp;
 339         const struct ip *ip;
 340         const char *str, *fmt;
 341         const struct ip *oip;
 342         const struct udphdr *ouh;
 343         const u_int8_t *obj_tptr;
 344         u_int32_t raw_label;
 345         const u_char *snapend_save;
 346         const struct icmp_mpls_ext_object_header_t *icmp_mpls_ext_object_header;
 347         u_int hlen, dport, mtu, obj_tlen, obj_class_num, obj_ctype;
 348         char buf[MAXHOSTNAMELEN + 100];
 349
 350         dp = (struct icmp *)bp;
 351         ext_dp = (struct icmp_ext_t *)bp;
 352         ip = (struct ip *)bp2;
 353         str = buf;
 354
 355         TCHECK(dp->icmp_code);
 356         switch (dp->icmp_type) {
 357
 358         case ICMP_ECHO:
 359         case ICMP_ECHOREPLY:
 360                 TCHECK(dp->icmp_seq);
 361                 (void)snprintf(buf, sizeof(buf), "echo %s, id %u, seq %u",
 362                                dp->icmp_type == ICMP_ECHO ?
 363                                "request" : "reply",
 364                                EXTRACT_16BITS(&dp->icmp_id),
 365                                EXTRACT_16BITS(&dp->icmp_seq));
 366                 break;
 367
 368         case ICMP_UNREACH:
 369                 TCHECK(dp->icmp_ip.ip_dst);
 370                 switch (dp->icmp_code) {
 371
 372                 case ICMP_UNREACH_PROTOCOL:
 373                         TCHECK(dp->icmp_ip.ip_p);
 374                         (void)snprintf(buf, sizeof(buf),
 375                             "%s protocol %d unreachable",
 376                             ipaddr_string(&dp->icmp_ip.ip_dst),
 377                             dp->icmp_ip.ip_p);
 378                         break;
 379
 380                 case ICMP_UNREACH_PORT:
 381                         TCHECK(dp->icmp_ip.ip_p);
 382                         oip = &dp->icmp_ip;
 383                         hlen = IP_HL(oip) * 4;
 384                         ouh = (struct udphdr *)(((u_char *)oip) + hlen);
 385                         TCHECK(ouh->uh_dport);
 386                         dport = EXTRACT_16BITS(&ouh->uh_dport);
 387                         switch (oip->ip_p) {
 388
 389                         case IPPROTO_TCP:
 390                                 (void)snprintf(buf, sizeof(buf),
 391                                         "%s tcp port %s unreachable",
 392                                         ipaddr_string(&oip->ip_dst),
 393                                         tcpport_string(dport));
 394                                 break;
 395
 396                         case IPPROTO_UDP:
 397                                 (void)snprintf(buf, sizeof(buf),
 398                                         "%s udp port %s unreachable",
 399                                         ipaddr_string(&oip->ip_dst),
 400                                         udpport_string(dport));
 401                                 break;
 402
 403                         default:
 404                                 (void)snprintf(buf, sizeof(buf),
 405                                         "%s protocol %d port %d unreachable",
 406                                         ipaddr_string(&oip->ip_dst),
 407                                         oip->ip_p, dport);
 408                                 break;
 409                         }
 410                         break;
 411
 412                 case ICMP_UNREACH_NEEDFRAG:
 413                     {
 414                         register const struct mtu_discovery *mp;
 415                         mp = (struct mtu_discovery *)(u_char *)&dp->icmp_void;
 416                         mtu = EXTRACT_16BITS(&mp->nexthopmtu);
 417                         if (mtu) {
 418                                 (void)snprintf(buf, sizeof(buf),
 419                                     "%s unreachable - need to frag (mtu %d)",
 420                                     ipaddr_string(&dp->icmp_ip.ip_dst), mtu);
 421                         } else {
 422                                 (void)snprintf(buf, sizeof(buf),
 423                                     "%s unreachable - need to frag",
 424                                     ipaddr_string(&dp->icmp_ip.ip_dst));
 425                         }
 426                     }
 427                         break;
 428
 429                 default:
 430                         fmt = tok2str(unreach2str, "#%d %%s unreachable",
 431                             dp->icmp_code);
 432                         (void)snprintf(buf, sizeof(buf), fmt,
 433                             ipaddr_string(&dp->icmp_ip.ip_dst));
 434                         break;
 435                 }
 436                 break;
 437
 438         case ICMP_REDIRECT:
 439                 TCHECK(dp->icmp_ip.ip_dst);
 440                 fmt = tok2str(type2str, "redirect-#%d %%s to net %%s",
 441                     dp->icmp_code);
 442                 (void)snprintf(buf, sizeof(buf), fmt,
 443                     ipaddr_string(&dp->icmp_ip.ip_dst),
 444                     ipaddr_string(&dp->icmp_gwaddr));
 445                 break;
 446
 447         case ICMP_ROUTERADVERT:
 448             {
 449                 register const struct ih_rdiscovery *ihp;
 450                 register const struct id_rdiscovery *idp;
 451                 u_int lifetime, num, size;
 452
 453                 (void)snprintf(buf, sizeof(buf), "router advertisement");
 454                 cp = buf + strlen(buf);
 455
 456                 ihp = (struct ih_rdiscovery *)&dp->icmp_void;
 457                 TCHECK(*ihp);
 458                 (void)strncpy(cp, " lifetime ", sizeof(buf) - (cp - buf));
 459                 cp = buf + strlen(buf);
 460                 lifetime = EXTRACT_16BITS(&ihp->ird_lifetime);
 461                 if (lifetime < 60) {
 462                         (void)snprintf(cp, sizeof(buf) - (cp - buf), "%u",
 463                             lifetime);
 464                 } else if (lifetime < 60 * 60) {
 465                         (void)snprintf(cp, sizeof(buf) - (cp - buf), "%u:%02u",
 466                             lifetime / 60, lifetime % 60);
 467                 } else {
 468                         (void)snprintf(cp, sizeof(buf) - (cp - buf),
 469                             "%u:%02u:%02u",
 470                             lifetime / 3600,
 471                             (lifetime % 3600) / 60,
 472                             lifetime % 60);
 473                 }
 474                 cp = buf + strlen(buf);
 475
 476                 num = ihp->ird_addrnum;
 477                 (void)snprintf(cp, sizeof(buf) - (cp - buf), " %d:", num);
 478                 cp = buf + strlen(buf);
 479
 480                 size = ihp->ird_addrsiz;
 481                 if (size != 2) {
 482                         (void)snprintf(cp, sizeof(buf) - (cp - buf),
 483                             " [size %d]", size);
 484                         break;
 485                 }
 486                 idp = (struct id_rdiscovery *)&dp->icmp_data;
 487                 while (num-- > 0) {
 488                         TCHECK(*idp);
 489                         (void)snprintf(cp, sizeof(buf) - (cp - buf), " {%s %u}",
 490                             ipaddr_string(&idp->ird_addr),
 491                             EXTRACT_32BITS(&idp->ird_pref));
 492                         cp = buf + strlen(buf);
 493                         ++idp;
 494                 }
 495             }
 496                 break;
 497
 498         case ICMP_TIMXCEED:
 499                 TCHECK(dp->icmp_ip.ip_dst);
 500                 switch (dp->icmp_code) {
 501
 502                 case ICMP_TIMXCEED_INTRANS:
 503                         str = "time exceeded in-transit";
 504                         break;
 505
 506                 case ICMP_TIMXCEED_REASS:
 507                         str = "ip reassembly time exceeded";
 508                         break;
 509
 510                 default:
 511                         (void)snprintf(buf, sizeof(buf), "time exceeded-#%d",
 512                             dp->icmp_code);
 513                         break;
 514                 }
 515                 break;
 516
 517         case ICMP_PARAMPROB:
 518                 if (dp->icmp_code)
 519                         (void)snprintf(buf, sizeof(buf),
 520                             "parameter problem - code %d", dp->icmp_code);
 521                 else {
 522                         TCHECK(dp->icmp_pptr);
 523                         (void)snprintf(buf, sizeof(buf),
 524                             "parameter problem - octet %d", dp->icmp_pptr);
 525                 }
 526                 break;
 527
 528         case ICMP_MASKREPLY:
 529                 TCHECK(dp->icmp_mask);
 530                 (void)snprintf(buf, sizeof(buf), "address mask is 0x%08x",
 531                     EXTRACT_32BITS(&dp->icmp_mask));
 532                 break;
 533
 534         case ICMP_TSTAMP:
 535                 TCHECK(dp->icmp_seq);
 536                 (void)snprintf(buf, sizeof(buf),
 537                     "time stamp query id %u seq %u",
 538                     EXTRACT_16BITS(&dp->icmp_id),
 539                     EXTRACT_16BITS(&dp->icmp_seq));
 540                 break;
 541
 542         case ICMP_TSTAMPREPLY:
 543                 TCHECK(dp->icmp_ttime);
 544                 (void)snprintf(buf, sizeof(buf),
 545                     "time stamp reply id %u seq %u: org %s",
 546                                EXTRACT_16BITS(&dp->icmp_id),
 547                                EXTRACT_16BITS(&dp->icmp_seq),
 548                                icmp_tstamp_print(EXTRACT_32BITS(&dp->icmp_otime)));
 549
 550                 (void)snprintf(buf+strlen(buf),sizeof(buf)-strlen(buf),", recv %s",
 551                          icmp_tstamp_print(EXTRACT_32BITS(&dp->icmp_rtime)));
 552                 (void)snprintf(buf+strlen(buf),sizeof(buf)-strlen(buf),", xmit %s",
 553                          icmp_tstamp_print(EXTRACT_32BITS(&dp->icmp_ttime)));
 554                 break;
 555
 556         default:
 557                 str = tok2str(icmp2str, "type-#%d", dp->icmp_type);
 558                 break;
 559         }
 560         (void)printf("ICMP %s, length %u", str, plen);
 561         if (vflag && !fragmented) { /* don't attempt checksumming if this is a frag */
 562                 u_int16_t sum, icmp_sum;
 563                 if (TTEST2(*bp, plen)) {
 564                         sum = in_cksum((u_short*)dp, plen, 0);
 565                         if (sum != 0) {
 566                                 icmp_sum = EXTRACT_16BITS(&dp->icmp_cksum);
 567                                 (void)printf(" (wrong icmp cksum %x (->%x)!)",
 568                                              icmp_sum,
 569                                              in_cksum_shouldbe(icmp_sum, sum));
 570                         }
 571                 }
 572         }
 573
 574         /*
 575          * print the remnants of the IP packet.
 576          * save the snaplength as this may get overidden in the IP printer.
 577          */
 578         if (vflag >= 1 && !ICMP_INFOTYPE(dp->icmp_type)) {
 579                 bp += 8;
 580                 (void)printf("\n\t");
 581                 ip = (struct ip *)bp;
 582                 snaplen = snapend - bp;
 583                 snapend_save = snapend;
 584                 ip_print(gndo, bp, EXTRACT_16BITS(&ip->ip_len));
 585                 snapend = snapend_save;
 586         }
 587
 588         /*
 589          * Attempt to decode the MPLS extensions only for some ICMP types.
 590          */
 591         if (vflag >= 1 && plen > ICMP_EXTD_MINLEN && ICMP_MPLS_EXT_TYPE(dp->icmp_type)) {
 592
 593             TCHECK(*ext_dp);
 594
 595             /*
 596              * Check first if the mpls extension header shows a non-zero length.
 597              * If the length field is not set then silently verify the checksum
 598              * to check if an extension header is present. This is expedient,
 599              * however not all implementations set the length field proper.
 600              */
 601             if (!ext_dp->icmp_length &&
 602                 in_cksum((const u_short *)&ext_dp->icmp_ext_version_res,
 603                          plen - ICMP_EXTD_MINLEN, 0)) {
 604                 return;
 605             }
 606
 607             printf("\n\tMPLS extension v%u",
 608                    ICMP_MPLS_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res)));
 609
 610             /*
 611              * Sanity checking of the header.
 612              */
 613             if (ICMP_MPLS_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res)) !=
 614                 ICMP_MPLS_EXT_VERSION) {
 615                 printf(" packet not supported");
 616                 return;
 617             }
 618
 619             hlen = plen - ICMP_EXTD_MINLEN;
 620             printf(", checksum 0x%04x (%scorrect), length %u",
 621                    EXTRACT_16BITS(ext_dp->icmp_ext_checksum),
 622                    in_cksum((const u_short *)&ext_dp->icmp_ext_version_res,
 623                             plen - ICMP_EXTD_MINLEN, 0) ? "in" : "",
 624                    hlen);
 625
 626             hlen -= 4; /* subtract common header size */
 627             obj_tptr = (u_int8_t *)ext_dp->icmp_ext_data;
 628
 629             while (hlen > sizeof(struct icmp_mpls_ext_object_header_t)) {
 630
 631                 icmp_mpls_ext_object_header = (struct icmp_mpls_ext_object_header_t *)obj_tptr;
 632                 TCHECK(*icmp_mpls_ext_object_header);
 633                 obj_tlen = EXTRACT_16BITS(icmp_mpls_ext_object_header->length);
 634                 obj_class_num = icmp_mpls_ext_object_header->class_num;
 635                 obj_ctype = icmp_mpls_ext_object_header->ctype;
 636                 obj_tptr += sizeof(struct icmp_mpls_ext_object_header_t);
 637
 638                 printf("\n\t  %s Object (%u), Class-Type: %u, length %u",
 639                        tok2str(icmp_mpls_ext_obj_values,"unknown",obj_class_num),
 640                        obj_class_num,
 641                        obj_ctype,
 642                        obj_tlen);
 643
 644                 hlen-=sizeof(struct icmp_mpls_ext_object_header_t); /* length field includes tlv header */
 645
 646                 /* infinite loop protection */
 647                 if ((obj_class_num == 0) ||
 648                     (obj_tlen < sizeof(struct icmp_mpls_ext_object_header_t))) {
 649                     return;
 650                 }
 651                 obj_tlen-=sizeof(struct icmp_mpls_ext_object_header_t);
 652
 653                 switch (obj_class_num) {
 654                 case 1:
 655                     switch(obj_ctype) {
 656                     case 1:
 657                         TCHECK2(*obj_tptr, 4);
 658                         raw_label = EXTRACT_32BITS(obj_tptr);
 659                         printf("\n\t    label %u, exp %u", MPLS_LABEL(raw_label), MPLS_EXP(raw_label));
 660                         if (MPLS_STACK(raw_label))
 661                             printf(", [S]");
 662                         printf(", ttl %u", MPLS_TTL(raw_label));
 663                         break;
 664                     default:
 665                         print_unknown_data(obj_tptr, "\n\t    ", obj_tlen);
 666                     }
 667                     break;
 668
 669                /*
 670                 *  FIXME those are the defined objects that lack a decoder
 671                 *  you are welcome to contribute code ;-)
 672                 */
 673                 case 2:
 674                 default:
 675                     print_unknown_data(obj_tptr, "\n\t    ", obj_tlen);
 676                     break;
 677                 }
 678                 if (hlen < obj_tlen)
 679                     break;
 680                 hlen -= obj_tlen;
 681                 obj_tptr += obj_tlen;
 682             }
 683         }
 684
 685         return;
 686 trunc:
 687         fputs("[|icmp]", stdout);
 688 }