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 #ifndef lint
  23 static const char rcsid[] _U_ =
  24     "@(#) $Header: /tcpdump/master/tcpdump/print-ip.c,v 1.135 2004-03-24 09:00:08 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 <stdlib.h>
  35 #include <string.h>
  36
  37 #include "addrtoname.h"
  38 #include "interface.h"
  39 #include "extract.h"                    /* must come after interface.h */
  40
  41 #include "ip.h"
  42 #include "ipproto.h"
  43
  44 /*
  45  * print the recorded route in an IP RR, LSRR or SSRR option.
  46  */
  47 static void
  48 ip_printroute(const char *type, register const u_char *cp, u_int length)
  49 {
  50         register u_int ptr;
  51         register u_int len;
  52
  53         if (length < 3) {
  54                 printf(" [bad length %u]", length);
  55                 return;
  56         }
  57         printf(" %s{", type);
  58         if ((length + 1) & 3)
  59                 printf(" [bad length %u]", length);
  60         ptr = cp[2] - 1;
  61         if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1)
  62                 printf(" [bad ptr %u]", cp[2]);
  63
  64         type = "";
  65         for (len = 3; len < length; len += 4) {
  66                 if (ptr == len)
  67                         type = "#";
  68                 printf("%s%s", type, ipaddr_string(&cp[len]));
  69                 type = " ";
  70         }
  71         printf("%s}", ptr == len? "#" : "");
  72 }
  73
  74 /*
  75  * If source-routing is present, return the final destination.
  76  * Otherwise, return IP destination.
  77  *
  78  * This is used for UDP and TCP pseudo-header in the checksum
  79  * calculation.
  80  */
  81 u_int32_t
  82 ip_finddst(const struct ip *ip)
  83 {
  84         int length;
  85         int len;
  86         const u_char *cp;
  87         u_int32_t retval;
  88
  89         cp = (const u_char *)(ip + 1);
  90         length = (IP_HL(ip) << 2) - sizeof(struct ip);
  91
  92         for (; length > 0; cp += len, length -= len) {
  93                 int tt;
  94
  95                 TCHECK(*cp);
  96                 tt = *cp;
  97                 if (tt == IPOPT_NOP || tt == IPOPT_EOL)
  98                         len = 1;
  99                 else {
 100                         TCHECK(cp[1]);
 101                         len = cp[1];
 102                 }
 103                 if (len < 2) {
 104                         return 0;
 105                 }
 106                 TCHECK2(*cp, len);
 107                 switch (tt) {
 108
 109                 case IPOPT_SSRR:
 110                 case IPOPT_LSRR:
 111                         if (len < 7)
 112                                 return 0;
 113                         memcpy(&retval, cp + len - 4, 4);
 114                         return retval;
 115                 }
 116         }
 117         return ip->ip_dst.s_addr;
 118
 119 trunc:
 120         return 0;
 121 }
 122
 123 static void
 124 ip_printts(register const u_char *cp, u_int length)
 125 {
 126         register u_int ptr;
 127         register u_int len;
 128         int hoplen;
 129         const char *type;
 130
 131         if (length < 4) {
 132                 printf("[bad length %d]", length);
 133                 return;
 134         }
 135         printf(" TS{");
 136         hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
 137         if ((length - 4) & (hoplen-1))
 138                 printf("[bad length %d]", length);
 139         ptr = cp[2] - 1;
 140         len = 0;
 141         if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
 142                 printf("[bad ptr %d]", cp[2]);
 143         switch (cp[3]&0xF) {
 144         case IPOPT_TS_TSONLY:
 145                 printf("TSONLY");
 146                 break;
 147         case IPOPT_TS_TSANDADDR:
 148                 printf("TS+ADDR");
 149                 break;
 150         /*
 151          * prespecified should really be 3, but some ones might send 2
 152          * instead, and the IPOPT_TS_PRESPEC constant can apparently
 153          * have both values, so we have to hard-code it here.
 154          */
 155
 156         case 2:
 157                 printf("PRESPEC2.0");
 158                 break;
 159         case 3:                 /* IPOPT_TS_PRESPEC */
 160                 printf("PRESPEC");
 161                 break;
 162         default:
 163                 printf("[bad ts type %d]", cp[3]&0xF);
 164                 goto done;
 165         }
 166
 167         type = " ";
 168         for (len = 4; len < length; len += hoplen) {
 169                 if (ptr == len)
 170                         type = " ^ ";
 171                 printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]),
 172                        hoplen!=8 ? "" : ipaddr_string(&cp[len]));
 173                 type = " ";
 174         }
 175
 176 done:
 177         printf("%s", ptr == len ? " ^ " : "");
 178
 179         if (cp[3]>>4)
 180                 printf(" [%d hops not recorded]} ", cp[3]>>4);
 181         else
 182                 printf("}");
 183 }
 184
 185 /*
 186  * print IP options.
 187  */
 188 static void
 189 ip_optprint(register const u_char *cp, u_int length)
 190 {
 191         register u_int len;
 192
 193         for (; length > 0; cp += len, length -= len) {
 194                 int tt;
 195
 196                 TCHECK(*cp);
 197                 tt = *cp;
 198                 if (tt == IPOPT_NOP || tt == IPOPT_EOL)
 199                         len = 1;
 200                 else {
 201                         TCHECK(cp[1]);
 202                         len = cp[1];
 203                         if (len < 2) {
 204                                 printf("[|ip op len %d]", len);
 205                                 return;
 206                         }
 207                         TCHECK2(*cp, len);
 208                 }
 209                 switch (tt) {
 210
 211                 case IPOPT_EOL:
 212                         printf(" EOL");
 213                         if (length > 1)
 214                                 printf("-%d", length - 1);
 215                         return;
 216
 217                 case IPOPT_NOP:
 218                         printf(" NOP");
 219                         break;
 220
 221                 case IPOPT_TS:
 222                         ip_printts(cp, len);
 223                         break;
 224
 225 #ifndef IPOPT_SECURITY
 226 #define IPOPT_SECURITY 130
 227 #endif /* IPOPT_SECURITY */
 228                 case IPOPT_SECURITY:
 229                         printf(" SECURITY{%d}", len);
 230                         break;
 231
 232                 case IPOPT_RR:
 233                         ip_printroute("RR", cp, len);
 234                         break;
 235
 236                 case IPOPT_SSRR:
 237                         ip_printroute("SSRR", cp, len);
 238                         break;
 239
 240                 case IPOPT_LSRR:
 241                         ip_printroute("LSRR", cp, len);
 242                         break;
 243
 244 #ifndef IPOPT_RA
 245 #define IPOPT_RA 148            /* router alert */
 246 #endif
 247                 case IPOPT_RA:
 248                         printf(" RA");
 249                         if (len != 4)
 250                                 printf("{%d}", len);
 251                         else {
 252                                 TCHECK(cp[3]);
 253                                 if (cp[2] || cp[3])
 254                                         printf("%d.%d", cp[2], cp[3]);
 255                         }
 256                         break;
 257
 258                 default:
 259                         printf(" IPOPT-%d{%d}", cp[0], len);
 260                         break;
 261                 }
 262         }
 263         return;
 264
 265 trunc:
 266         printf("[|ip]");
 267 }
 268
 269 /*
 270  * compute an IP header checksum.
 271  * don't modifiy the packet.
 272  */
 273 u_short
 274 in_cksum(const u_short *addr, register u_int len, int csum)
 275 {
 276         int nleft = len;
 277         const u_short *w = addr;
 278         u_short answer;
 279         int sum = csum;
 280
 281         /*
 282          *  Our algorithm is simple, using a 32 bit accumulator (sum),
 283          *  we add sequential 16 bit words to it, and at the end, fold
 284          *  back all the carry bits from the top 16 bits into the lower
 285          *  16 bits.
 286          */
 287         while (nleft > 1)  {
 288                 sum += *w++;
 289                 nleft -= 2;
 290         }
 291         if (nleft == 1)
 292                 sum += htons(*(u_char *)w<<8);
 293
 294         /*
 295          * add back carry outs from top 16 bits to low 16 bits
 296          */
 297         sum = (sum >> 16) + (sum & 0xffff);     /* add hi 16 to low 16 */
 298         sum += (sum >> 16);                     /* add carry */
 299         answer = ~sum;                          /* truncate to 16 bits */
 300         return (answer);
 301 }
 302
 303 /*
 304  * Given the host-byte-order value of the checksum field in a packet
 305  * header, and the network-byte-order computed checksum of the data
 306  * that the checksum covers (including the checksum itself), compute
 307  * what the checksum field *should* have been.
 308  */
 309 u_int16_t
 310 in_cksum_shouldbe(u_int16_t sum, u_int16_t computed_sum)
 311 {
 312         u_int32_t shouldbe;
 313
 314         /*
 315          * The value that should have gone into the checksum field
 316          * is the negative of the value gotten by summing up everything
 317          * *but* the checksum field.
 318          *
 319          * We can compute that by subtracting the value of the checksum
 320          * field from the sum of all the data in the packet, and then
 321          * computing the negative of that value.
 322          *
 323          * "sum" is the value of the checksum field, and "computed_sum"
 324          * is the negative of the sum of all the data in the packets,
 325          * so that's -(-computed_sum - sum), or (sum + computed_sum).
 326          *
 327          * All the arithmetic in question is one's complement, so the
 328          * addition must include an end-around carry; we do this by
 329          * doing the arithmetic in 32 bits (with no sign-extension),
 330          * and then adding the upper 16 bits of the sum, which contain
 331          * the carry, to the lower 16 bits of the sum, and then do it
 332          * again in case *that* sum produced a carry.
 333          *
 334          * As RFC 1071 notes, the checksum can be computed without
 335          * byte-swapping the 16-bit words; summing 16-bit words
 336          * on a big-endian machine gives a big-endian checksum, which
 337          * can be directly stuffed into the big-endian checksum fields
 338          * in protocol headers, and summing words on a little-endian
 339          * machine gives a little-endian checksum, which must be
 340          * byte-swapped before being stuffed into a big-endian checksum
 341          * field.
 342          *
 343          * "computed_sum" is a network-byte-order value, so we must put
 344          * it in host byte order before subtracting it from the
 345          * host-byte-order value from the header; the adjusted checksum
 346          * will be in host byte order, which is what we'll return.
 347          */
 348         shouldbe = sum;
 349         shouldbe += ntohs(computed_sum);
 350         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 351         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 352         return shouldbe;
 353 }
 354
 355 #ifndef IP_MF
 356 #define IP_MF 0x2000
 357 #endif /* IP_MF */
 358 #ifndef IP_DF
 359 #define IP_DF 0x4000
 360 #endif /* IP_DF */
 361 #define IP_RES 0x8000
 362
 363 static struct tok ip_frag_values[] = {
 364         { IP_MF,        "+" },
 365         { IP_DF,        "DF" },
 366         { IP_RES,       "rsvd" }, /* The RFC3514 evil ;-) bit */
 367         { 0,            NULL }
 368 };
 369
 370 /*
 371  * print an IP datagram.
 372  */
 373 void
 374 ip_print(register const u_char *bp, register u_int length)
 375 {
 376         register const struct ip *ip;
 377         register u_int hlen, len, len0, off;
 378         const u_char *ipend;
 379         register const u_char *cp;
 380         u_char nh;
 381         int advance;
 382         struct protoent *proto;
 383         u_int16_t sum, ip_sum;
 384
 385         ip = (const struct ip *)bp;
 386         if (IP_V(ip) != 4) { /* print version if != 4 */
 387             printf("IP%u ", IP_V(ip));
 388             if (IP_V(ip) == 6)
 389                 printf(", wrong link-layer encapsulation");
 390         }
 391         else
 392             printf("IP ");
 393
 394         if ((u_char *)(ip + 1) > snapend) {
 395                 printf("[|ip]");
 396                 return;
 397         }
 398         if (length < sizeof (struct ip)) {
 399                 (void)printf("truncated-ip %d", length);
 400                 return;
 401         }
 402         hlen = IP_HL(ip) * 4;
 403         if (hlen < sizeof (struct ip)) {
 404                 (void)printf("bad-hlen %u", hlen);
 405                 return;
 406         }
 407
 408         len = EXTRACT_16BITS(&ip->ip_len);
 409         if (length < len)
 410                 (void)printf("truncated-ip - %u bytes missing! ",
 411                         len - length);
 412         if (len < hlen) {
 413                 (void)printf("bad-len %u", len);
 414                 return;
 415         }
 416
 417         /*
 418          * Cut off the snapshot length to the end of the IP payload.
 419          */
 420         ipend = bp + len;
 421         if (ipend < snapend)
 422                 snapend = ipend;
 423
 424         len -= hlen;
 425         len0 = len;
 426
 427         off = EXTRACT_16BITS(&ip->ip_off);
 428
 429         if (vflag) {
 430             (void)printf("(tos 0x%x", (int)ip->ip_tos);
 431             /* ECN bits */
 432             if (ip->ip_tos & 0x03) {
 433                 switch (ip->ip_tos & 0x03) {
 434                 case 1:
 435                     (void)printf(",ECT(1)");
 436                     break;
 437                 case 2:
 438                     (void)printf(",ECT(0)");
 439                     break;
 440                 case 3:
 441                     (void)printf(",CE");
 442                 }
 443             }
 444
 445             if (ip->ip_ttl >= 1)
 446                 (void)printf(", ttl %3u", ip->ip_ttl);
 447
 448             /*
 449              * for the firewall guys, print id, offset.
 450              * On all but the last stick a "+" in the flags portion.
 451              * For unfragmented datagrams, note the don't fragment flag.
 452              */
 453
 454             (void)printf(", id %u, offset %u, flags [%s], proto %u",
 455                              EXTRACT_16BITS(&ip->ip_id),
 456                              (off & 0x1fff) * 8,
 457                              bittok2str(ip_frag_values, "none", off & 0xe000 ),
 458                              ip->ip_p);
 459
 460             (void)printf(", length: %u", EXTRACT_16BITS(&ip->ip_len));
 461
 462             if ((hlen - sizeof(struct ip)) > 0) {
 463                 (void)printf(", optlength: %u (", hlen - (u_int)sizeof(struct ip));
 464                 ip_optprint((u_char *)(ip + 1), hlen - sizeof(struct ip));
 465                 printf(" )");
 466             }
 467
 468             if ((u_char *)ip + hlen <= snapend) {
 469                 sum = in_cksum((const u_short *)ip, hlen, 0);
 470                 if (sum != 0) {
 471                     ip_sum = EXTRACT_16BITS(&ip->ip_sum);
 472                     (void)printf(", bad cksum %x (->%x)!", ip_sum,
 473                              in_cksum_shouldbe(ip_sum, sum));
 474                 }
 475             }
 476
 477             printf(") ");
 478         }
 479
 480         /*
 481          * If this is fragment zero, hand it to the next higher
 482          * level protocol.
 483          */
 484         if ((off & 0x1fff) == 0) {
 485                 cp = (const u_char *)ip + hlen;
 486                 nh = ip->ip_p;
 487
 488                 if (nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 489                     nh != IPPROTO_SCTP) {
 490                         (void)printf("%s > %s: ", ipaddr_string(&ip->ip_src),
 491                                 ipaddr_string(&ip->ip_dst));
 492                 }
 493 again:
 494                 switch (nh) {
 495
 496                 case IPPROTO_AH:
 497                         nh = *cp;
 498                         advance = ah_print(cp);
 499                         if (advance <= 0)
 500                                 break;
 501                         cp += advance;
 502                         len -= advance;
 503                         goto again;
 504
 505                 case IPPROTO_ESP:
 506                     {
 507                         int enh, padlen;
 508                         advance = esp_print(cp, (const u_char *)ip, &enh, &padlen);
 509                         if (advance <= 0)
 510                                 break;
 511                         cp += advance;
 512                         len -= advance + padlen;
 513                         nh = enh & 0xff;
 514                         goto again;
 515                     }
 516
 517                 case IPPROTO_IPCOMP:
 518                     {
 519                         int enh;
 520                         advance = ipcomp_print(cp, &enh);
 521                         if (advance <= 0)
 522                                 break;
 523                         cp += advance;
 524                         len -= advance;
 525                         nh = enh & 0xff;
 526                         goto again;
 527                     }
 528
 529                 case IPPROTO_SCTP:
 530                         sctp_print(cp, (const u_char *)ip, len);
 531                         break;
 532
 533                 case IPPROTO_TCP:
 534                         tcp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 535                         break;
 536
 537                 case IPPROTO_UDP:
 538                         udp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 539                         break;
 540
 541                 case IPPROTO_ICMP:
 542                         /* pass on the MF bit plus the offset to detect fragments */
 543                         icmp_print(cp, len, (const u_char *)ip, (off & 0x3fff));
 544                         break;
 545
 546                 case IPPROTO_IGRP:
 547                         igrp_print(cp, len, (const u_char *)ip);
 548                         break;
 549
 550                 case IPPROTO_ND:
 551                         (void)printf(" nd %d", len);
 552                         break;
 553
 554                 case IPPROTO_EGP:
 555                         egp_print(cp);
 556                         break;
 557
 558                 case IPPROTO_OSPF:
 559                         ospf_print(cp, len, (const u_char *)ip);
 560                         break;
 561
 562                 case IPPROTO_IGMP:
 563                         igmp_print(cp, len);
 564                         break;
 565
 566                 case IPPROTO_IPV4:
 567                         /* DVMRP multicast tunnel (ip-in-ip encapsulation) */
 568                         ip_print(cp, len);
 569                         if (! vflag) {
 570                                 printf(" (ipip-proto-4)");
 571                                 return;
 572                         }
 573                         break;
 574
 575 #ifdef INET6
 576                 case IPPROTO_IPV6:
 577                         /* ip6-in-ip encapsulation */
 578                         ip6_print(cp, len);
 579                         break;
 580 #endif /*INET6*/
 581
 582                 case IPPROTO_RSVP:
 583                         rsvp_print(cp, len);
 584                         break;
 585
 586                 case IPPROTO_GRE:
 587                         /* do it */
 588                         gre_print(cp, len);
 589                         break;
 590
 591                 case IPPROTO_MOBILE:
 592                         mobile_print(cp, len);
 593                         break;
 594
 595                 case IPPROTO_PIM:
 596                         pim_print(cp, len);
 597                         break;
 598
 599                 case IPPROTO_VRRP:
 600                         vrrp_print(cp, len, ip->ip_ttl);
 601                         break;
 602
 603                 default:
 604                         if ((proto = getprotobynumber(nh)) != NULL)
 605                                 (void)printf(" %s", proto->p_name);
 606                         else
 607                                 (void)printf(" ip-proto-%d", nh);
 608                         printf(" %d", len);
 609                         break;
 610                 }
 611         } else {
 612             /* Ultra quiet now means that all this stuff should be suppressed */
 613             if (qflag > 1) return;
 614
 615             /*
 616              * if this isn't the first frag, we're missing the
 617              * next level protocol header.  print the ip addr
 618              * and the protocol.
 619              */
 620             if (off & 0x1fff) {
 621                 (void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
 622                              ipaddr_string(&ip->ip_dst));
 623                 if ((proto = getprotobynumber(ip->ip_p)) != NULL)
 624                     (void)printf(" %s", proto->p_name);
 625                 else
 626                     (void)printf(" ip-proto-%d", ip->ip_p);
 627             }
 628         }
 629 }
 630
 631 void
 632 ipN_print(register const u_char *bp, register u_int length)
 633 {
 634         struct ip *ip, hdr;
 635
 636         ip = (struct ip *)bp;
 637         if (length < 4) {
 638                 (void)printf("truncated-ip %d", length);
 639                 return;
 640         }
 641         memcpy (&hdr, (char *)ip, 4);
 642         switch (IP_V(&hdr)) {
 643         case 4:
 644                 ip_print (bp, length);
 645                 return;
 646 #ifdef INET6
 647         case 6:
 648                 ip6_print (bp, length);
 649                 return;
 650 #endif
 651         default:
 652                 (void)printf("unknown ip %d", IP_V(&hdr));
 653                 return;
 654         }
 655 }
 656
 657
 658