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[] =
  24     "@(#) $Header: /tcpdump/master/tcpdump/print-ip.c,v 1.110 2002-07-28 04:14:21 fenner Exp $ (LBL)";
  25 #endif
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <sys/param.h>
  32 #include <sys/time.h>
  33 #include <sys/socket.h>
  34
  35 #include <netinet/in.h>
  36
  37 #include <netdb.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42
  43 #include "addrtoname.h"
  44 #include "interface.h"
  45 #include "extract.h"                    /* must come after interface.h */
  46
  47 #include "ip.h"
  48
  49 /* Compatibility */
  50 #ifndef IPPROTO_ND
  51 #define IPPROTO_ND      77
  52 #endif
  53
  54 /*
  55  * print the recorded route in an IP RR, LSRR or SSRR option.
  56  */
  57 static void
  58 ip_printroute(const char *type, register const u_char *cp, u_int length)
  59 {
  60         register u_int ptr = cp[2] - 1;
  61         register u_int len;
  62
  63         printf(" %s{", type);
  64         if ((length + 1) & 3)
  65                 printf(" [bad length %d]", length);
  66         if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1)
  67                 printf(" [bad ptr %d]", cp[2]);
  68
  69         type = "";
  70         for (len = 3; len < length; len += 4) {
  71                 if (ptr == len)
  72                         type = "#";
  73                 printf("%s%s", type, ipaddr_string(&cp[len]));
  74                 type = " ";
  75         }
  76         printf("%s}", ptr == len? "#" : "");
  77 }
  78
  79 /*
  80  * If source-routing is present, return the final destination.
  81  * Otherwise, return IP destination.
  82  *
  83  * This is used for UDP and TCP pseudo-header in the checksum
  84  * calculation.
  85  */
  86 u_int32_t
  87 ip_finddst(const struct ip *ip)
  88 {
  89         int length;
  90         int len;
  91         const u_char *cp;
  92         uint32_t retval;
  93
  94         cp = (const u_char *)(ip + 1);
  95         length = (IP_HL(ip) << 2) - sizeof(struct ip);
  96
  97         for (; length > 0; cp += len, length -= len) {
  98                 int tt = *cp;
  99
 100                 if (tt == IPOPT_NOP || tt == IPOPT_EOL)
 101                         len = 1;
 102                 else {
 103                         if (&cp[1] >= snapend) {
 104                                 return 0;
 105                         }
 106                         len = cp[1];
 107                 }
 108                 if (len <= 0) {
 109                         return 0;
 110                 }
 111                 if (&cp[1] >= snapend || cp + len > snapend) {
 112                         return 0;
 113                 }
 114                 switch (tt) {
 115
 116                 case IPOPT_SSRR:
 117                 case IPOPT_LSRR:
 118                         memcpy(&retval, cp + len - 4, 4);
 119                         return retval;
 120                 }
 121         }
 122         return ip->ip_dst.s_addr;
 123 }
 124
 125 static void
 126 ip_printts(register const u_char *cp, u_int length)
 127 {
 128         register u_int ptr = cp[2] - 1;
 129         register u_int len = 0;
 130         int hoplen;
 131         char *type;
 132
 133         printf(" TS{");
 134         hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
 135         if ((length - 4) & (hoplen-1))
 136                 printf("[bad length %d]", length);
 137         if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
 138                 printf("[bad ptr %d]", cp[2]);
 139         switch (cp[3]&0xF) {
 140         case IPOPT_TS_TSONLY:
 141                 printf("TSONLY");
 142                 break;
 143         case IPOPT_TS_TSANDADDR:
 144                 printf("TS+ADDR");
 145                 break;
 146         /*
 147          * prespecified should really be 3, but some ones might send 2
 148          * instead, and the IPOPT_TS_PRESPEC constant can apparently
 149          * have both values, so we have to hard-code it here.
 150          */
 151
 152         case 2:
 153                 printf("PRESPEC2.0");
 154                 break;
 155         case 3:                 /* IPOPT_TS_PRESPEC */
 156                 printf("PRESPEC");
 157                 break;
 158         default:
 159                 printf("[bad ts type %d]", cp[3]&0xF);
 160                 goto done;
 161         }
 162
 163         type = " ";
 164         for (len = 4; len < length; len += hoplen) {
 165                 if (ptr == len)
 166                         type = " ^ ";
 167                 printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]),
 168                        hoplen!=8 ? "" : ipaddr_string(&cp[len]));
 169                 type = " ";
 170         }
 171
 172 done:
 173         printf("%s", ptr == len ? " ^ " : "");
 174
 175         if (cp[3]>>4)
 176                 printf(" [%d hops not recorded]} ", cp[3]>>4);
 177         else
 178                 printf("}");
 179 }
 180
 181 /*
 182  * print IP options.
 183  */
 184 static void
 185 ip_optprint(register const u_char *cp, u_int length)
 186 {
 187         register u_int len;
 188
 189         for (; length > 0; cp += len, length -= len) {
 190                 int tt = *cp;
 191
 192                 if (tt == IPOPT_NOP || tt == IPOPT_EOL)
 193                         len = 1;
 194                 else {
 195                         if (&cp[1] >= snapend) {
 196                                 printf("[|ip]");
 197                                 return;
 198                         }
 199                         len = cp[1];
 200                 }
 201                 if (len <= 0) {
 202                         printf("[|ip op len %d]", len);
 203                         return;
 204                 }
 205                 if (&cp[1] >= snapend || cp + len > snapend) {
 206                         printf("[|ip]");
 207                         return;
 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 if (cp[2] || cp[3])
 252                                 printf("%d.%d", cp[2], cp[3]);
 253                         break;
 254
 255                 default:
 256                         printf(" IPOPT-%d{%d}", cp[0], len);
 257                         break;
 258                 }
 259         }
 260 }
 261
 262 /*
 263  * compute an IP header checksum.
 264  * don't modifiy the packet.
 265  */
 266 u_short
 267 in_cksum(const u_short *addr, register u_int len, int csum)
 268 {
 269         int nleft = len;
 270         const u_short *w = addr;
 271         u_short answer;
 272         int sum = csum;
 273
 274         /*
 275          *  Our algorithm is simple, using a 32 bit accumulator (sum),
 276          *  we add sequential 16 bit words to it, and at the end, fold
 277          *  back all the carry bits from the top 16 bits into the lower
 278          *  16 bits.
 279          */
 280         while (nleft > 1)  {
 281                 sum += *w++;
 282                 nleft -= 2;
 283         }
 284         if (nleft == 1)
 285                 sum += htons(*(u_char *)w<<8);
 286
 287         /*
 288          * add back carry outs from top 16 bits to low 16 bits
 289          */
 290         sum = (sum >> 16) + (sum & 0xffff);     /* add hi 16 to low 16 */
 291         sum += (sum >> 16);                     /* add carry */
 292         answer = ~sum;                          /* truncate to 16 bits */
 293         return (answer);
 294 }
 295
 296 /*
 297  * Given the host-byte-order value of the checksum field in a packet
 298  * header, and the network-byte-order computed checksum of the data
 299  * that the checksum covers (including the checksum itself), compute
 300  * what the checksum field *should* have been.
 301  */
 302 u_int16_t
 303 in_cksum_shouldbe(u_int16_t sum, u_int16_t computed_sum)
 304 {
 305         u_int32_t shouldbe;
 306
 307         /*
 308          * The value that should have gone into the checksum field
 309          * is the negative of the value gotten by summing up everything
 310          * *but* the checksum field.
 311          *
 312          * We can compute that by subtracting the value of the checksum
 313          * field from the sum of all the data in the packet, and then
 314          * computing the negative of that value.
 315          *
 316          * "sum" is the value of the checksum field, and "computed_sum"
 317          * is the negative of the sum of all the data in the packets,
 318          * so that's -(-computed_sum - sum), or (sum + computed_sum).
 319          *
 320          * All the arithmetic in question is one's complement, so the
 321          * addition must include an end-around carry; we do this by
 322          * doing the arithmetic in 32 bits (with no sign-extension),
 323          * and then adding the upper 16 bits of the sum, which contain
 324          * the carry, to the lower 16 bits of the sum, and then do it
 325          * again in case *that* sum produced a carry.
 326          *
 327          * As RFC 1071 notes, the checksum can be computed without
 328          * byte-swapping the 16-bit words; summing 16-bit words
 329          * on a big-endian machine gives a big-endian checksum, which
 330          * can be directly stuffed into the big-endian checksum fields
 331          * in protocol headers, and summing words on a little-endian
 332          * machine gives a little-endian checksum, which must be
 333          * byte-swapped before being stuffed into a big-endian checksum
 334          * field.
 335          *
 336          * "computed_sum" is a network-byte-order value, so we must put
 337          * it in host byte order before subtracting it from the
 338          * host-byte-order value from the header; the adjusted checksum
 339          * will be in host byte order, which is what we'll return.
 340          */
 341         shouldbe = sum;
 342         shouldbe += ntohs(computed_sum);
 343         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 344         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 345         return shouldbe;
 346 }
 347
 348 /*
 349  * print an IP datagram.
 350  */
 351 void
 352 ip_print(register const u_char *bp, register u_int length)
 353 {
 354         register const struct ip *ip;
 355         register u_int hlen, len, len0, off;
 356         register const u_char *cp;
 357         u_char nh;
 358         int advance;
 359         struct protoent *proto;
 360
 361         ip = (const struct ip *)bp;
 362 #ifdef LBL_ALIGN
 363         /*
 364          * If the IP header is not aligned, copy into abuf.
 365          */
 366         if ((long)ip & 3) {
 367                 static u_char *abuf = NULL;
 368                 static int didwarn = 0;
 369
 370                 if (abuf == NULL) {
 371                         abuf = (u_char *)malloc(snaplen);
 372                         if (abuf == NULL)
 373                                 error("ip_print: malloc");
 374                 }
 375                 memcpy((char *)abuf, (char *)ip, min(length, snaplen));
 376                 snapend += abuf - (u_char *)ip;
 377                 packetp = abuf;
 378                 ip = (struct ip *)abuf;
 379                 /* We really want libpcap to give us aligned packets */
 380                 if (!didwarn) {
 381                         warning("compensating for unaligned libpcap packets");
 382                         ++didwarn;
 383                 }
 384         }
 385 #endif
 386         if ((u_char *)(ip + 1) > snapend) {
 387                 printf("[|ip]");
 388                 return;
 389         }
 390         if (length < sizeof (struct ip)) {
 391                 (void)printf("truncated-ip %d", length);
 392                 return;
 393         }
 394         hlen = IP_HL(ip) * 4;
 395         if (hlen < sizeof (struct ip)) {
 396                 (void)printf("bad-hlen %d", hlen);
 397                 return;
 398         }
 399
 400         len = ntohs(ip->ip_len);
 401         if (length < len)
 402                 (void)printf("truncated-ip - %d bytes missing! ",
 403                         len - length);
 404         len -= hlen;
 405         len0 = len;
 406
 407         printf("IP ");
 408
 409         off = ntohs(ip->ip_off);
 410
 411         if (vflag) {
 412             (void)printf("(tos 0x%x", (int)ip->ip_tos);
 413             /* ECN bits */
 414             if (ip->ip_tos & 0x03) {
 415                 switch (ip->ip_tos & 0x03) {
 416                 case 1:
 417                     (void)printf(",ECT(1)");
 418                     break;
 419                 case 2:
 420                     (void)printf(",ECT(0)");
 421                     break;
 422                 case 3:
 423                     (void)printf(",CE");
 424                 }
 425             }
 426
 427             if (ip->ip_ttl >= 1)
 428                 (void)printf(", ttl %d", (int)ip->ip_ttl);
 429
 430             if ((off & 0x3fff) == 0)
 431                 (void)printf(", id %d", (int)ntohs(ip->ip_id));
 432             (void)printf(", len %d) ", (int)ntohs(ip->ip_len));
 433         }
 434
 435         /*
 436          * If this is fragment zero, hand it to the next higher
 437          * level protocol.
 438          */
 439         if ((off & 0x1fff) == 0) {
 440                 cp = (const u_char *)ip + hlen;
 441                 nh = ip->ip_p;
 442
 443 #ifndef IPPROTO_SCTP
 444 #define IPPROTO_SCTP 132
 445 #endif
 446                 if (nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 447                     nh != IPPROTO_SCTP) {
 448                         (void)printf("%s > %s: ", ipaddr_string(&ip->ip_src),
 449                                 ipaddr_string(&ip->ip_dst));
 450                 }
 451 again:
 452                 switch (nh) {
 453
 454 #ifndef IPPROTO_AH
 455 #define IPPROTO_AH      51
 456 #endif
 457                 case IPPROTO_AH:
 458                         nh = *cp;
 459                         advance = ah_print(cp, (const u_char *)ip);
 460                         cp += advance;
 461                         len -= advance;
 462                         goto again;
 463
 464 #ifndef IPPROTO_ESP
 465 #define IPPROTO_ESP     50
 466 #endif
 467                 case IPPROTO_ESP:
 468                     {
 469                         int enh, padlen;
 470                         advance = esp_print(cp, (const u_char *)ip, &enh, &padlen);
 471                         cp += advance;
 472                         len -= advance + padlen;
 473                         if (enh < 0)
 474                                 break;
 475                         nh = enh & 0xff;
 476                         goto again;
 477                     }
 478
 479 #ifndef IPPROTO_IPCOMP
 480 #define IPPROTO_IPCOMP  108
 481 #endif
 482                 case IPPROTO_IPCOMP:
 483                     {
 484                         int enh;
 485                         advance = ipcomp_print(cp, (const u_char *)ip, &enh);
 486                         cp += advance;
 487                         len -= advance;
 488                         if (enh < 0)
 489                                 break;
 490                         nh = enh & 0xff;
 491                         goto again;
 492                     }
 493
 494                 case IPPROTO_SCTP:
 495                         sctp_print(cp, (const u_char *)ip, len);
 496                         break;
 497
 498                 case IPPROTO_TCP:
 499                         tcp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 500                         break;
 501
 502                 case IPPROTO_UDP:
 503                         udp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 504                         break;
 505
 506                 case IPPROTO_ICMP:
 507                         icmp_print(cp, len, (const u_char *)ip);
 508                         break;
 509
 510 #ifndef IPPROTO_IGRP
 511 #define IPPROTO_IGRP 9
 512 #endif
 513                 case IPPROTO_IGRP:
 514                         igrp_print(cp, len, (const u_char *)ip);
 515                         break;
 516
 517                 case IPPROTO_ND:
 518                         (void)printf(" nd %d", len);
 519                         break;
 520
 521                 case IPPROTO_EGP:
 522                         egp_print(cp, len, (const u_char *)ip);
 523                         break;
 524
 525 #ifndef IPPROTO_OSPF
 526 #define IPPROTO_OSPF 89
 527 #endif
 528                 case IPPROTO_OSPF:
 529                         ospf_print(cp, len, (const u_char *)ip);
 530                         break;
 531
 532 #ifndef IPPROTO_IGMP
 533 #define IPPROTO_IGMP 2
 534 #endif
 535                 case IPPROTO_IGMP:
 536                         igmp_print(cp, len);
 537                         break;
 538
 539                 case 4:
 540                         /* DVMRP multicast tunnel (ip-in-ip encapsulation) */
 541                         ip_print(cp, len);
 542                         if (! vflag) {
 543                                 printf(" (ipip-proto-4)");
 544                                 return;
 545                         }
 546                         break;
 547
 548 #ifdef INET6
 549 #ifndef IP6PROTO_ENCAP
 550 #define IP6PROTO_ENCAP 41
 551 #endif
 552                 case IP6PROTO_ENCAP:
 553                         /* ip6-in-ip encapsulation */
 554                         ip6_print(cp, len);
 555                         break;
 556 #endif /*INET6*/
 557
 558
 559 #ifndef IPPROTO_GRE
 560 #define IPPROTO_GRE 47
 561 #endif
 562                 case IPPROTO_GRE:
 563                         /* do it */
 564                         gre_print(cp, len);
 565                         break;
 566
 567 #ifndef IPPROTO_MOBILE
 568 #define IPPROTO_MOBILE 55
 569 #endif
 570                 case IPPROTO_MOBILE:
 571                         mobile_print(cp, len);
 572                         break;
 573
 574 #ifndef IPPROTO_PIM
 575 #define IPPROTO_PIM     103
 576 #endif
 577                 case IPPROTO_PIM:
 578                         pim_print(cp, len);
 579                         break;
 580
 581 #ifndef IPPROTO_VRRP
 582 #define IPPROTO_VRRP    112
 583 #endif
 584                 case IPPROTO_VRRP:
 585                         vrrp_print(cp, len, ip->ip_ttl);
 586                         break;
 587
 588                 default:
 589                         if ((proto = getprotobynumber(nh)) != NULL)
 590                                 (void)printf(" %s", proto->p_name);
 591                         else
 592                                 (void)printf(" ip-proto-%d", nh);
 593                         printf(" %d", len);
 594                         break;
 595                 }
 596         }
 597
 598         /* Ultra quiet now means that all this stuff should be suppressed */
 599         /* res 3-Nov-98 */
 600         if (qflag > 1) return;
 601
 602
 603         /*
 604          * for fragmented datagrams, print id:size@offset.  On all
 605          * but the last stick a "+".  For unfragmented datagrams, note
 606          * the don't fragment flag.
 607          */
 608         len = len0;     /* get the original length */
 609         if (off & 0x3fff) {
 610                 /*
 611                  * if this isn't the first frag, we're missing the
 612                  * next level protocol header.  print the ip addr
 613                  * and the protocol.
 614                  */
 615                 if (off & 0x1fff) {
 616                         (void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
 617                                       ipaddr_string(&ip->ip_dst));
 618                         if ((proto = getprotobynumber(ip->ip_p)) != NULL)
 619                                 (void)printf(" %s", proto->p_name);
 620                         else
 621                                 (void)printf(" ip-proto-%d", ip->ip_p);
 622                 }
 623 #ifndef IP_MF
 624 #define IP_MF 0x2000
 625 #endif /* IP_MF */
 626 #ifndef IP_DF
 627 #define IP_DF 0x4000
 628 #endif /* IP_DF */
 629                 (void)printf(" (frag %d:%u@%d%s)", ntohs(ip->ip_id), len,
 630                         (off & 0x1fff) * 8,
 631                         (off & IP_MF)? "+" : "");
 632
 633         } else if (off & IP_DF)
 634                 (void)printf(" (DF)");
 635
 636         if (vflag) {
 637                 u_int16_t sum, ip_sum;
 638                 char *sep = "";
 639
 640                 if ((u_char *)ip + hlen <= snapend) {
 641                         sum = in_cksum((const u_short *)ip, hlen, 0);
 642                         if (sum != 0) {
 643                                 ip_sum = ntohs(ip->ip_sum);
 644                                 (void)printf("%sbad cksum %x (->%x)!", sep,
 645                                              ip_sum,
 646                                              in_cksum_shouldbe(ip_sum, sum));
 647                                 sep = ", ";
 648                         }
 649                 }
 650                 if ((hlen -= sizeof(struct ip)) > 0) {
 651                         (void)printf("%soptlen=%d", sep, hlen);
 652                         ip_optprint((u_char *)(ip + 1), hlen);
 653                 }
 654         }
 655
 656 }
 657
 658 void
 659 ipN_print(register const u_char *bp, register u_int length)
 660 {
 661         struct ip *ip, hdr;
 662
 663         ip = (struct ip *)bp;
 664         if (length < 4) {
 665                 (void)printf("truncated-ip %d", length);
 666                 return;
 667         }
 668         memcpy (&hdr, (char *)ip, 4);
 669         switch (IP_V(&hdr)) {
 670         case 4:
 671                 ip_print (bp, length);
 672                 return;
 673 #ifdef INET6
 674         case 6:
 675                 ip6_print (bp, length);
 676                 return;
 677 #endif
 678         default:
 679                 (void)printf("unknown ip %d", IP_V(&hdr));
 680                 return;
 681         }
 682 }
 683
 684