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 1.126 2003-05-25 16:40:48 hannes 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
  43 /* Compatibility */
  44 #ifndef IPPROTO_ND
  45 #define IPPROTO_ND      77
  46 #endif
  47
  48 /*
  49  * print the recorded route in an IP RR, LSRR or SSRR option.
  50  */
  51 static void
  52 ip_printroute(const char *type, register const u_char *cp, u_int length)
  53 {
  54         register u_int ptr = cp[2] - 1;
  55         register u_int len;
  56
  57         printf(" %s{", type);
  58         if ((length + 1) & 3)
  59                 printf(" [bad length %d]", length);
  60         if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1)
  61                 printf(" [bad ptr %d]", cp[2]);
  62
  63         type = "";
  64         for (len = 3; len < length; len += 4) {
  65                 if (ptr == len)
  66                         type = "#";
  67                 printf("%s%s", type, ipaddr_string(&cp[len]));
  68                 type = " ";
  69         }
  70         printf("%s}", ptr == len? "#" : "");
  71 }
  72
  73 /*
  74  * If source-routing is present, return the final destination.
  75  * Otherwise, return IP destination.
  76  *
  77  * This is used for UDP and TCP pseudo-header in the checksum
  78  * calculation.
  79  */
  80 u_int32_t
  81 ip_finddst(const struct ip *ip)
  82 {
  83         int length;
  84         int len;
  85         const u_char *cp;
  86         u_int32_t retval;
  87
  88         cp = (const u_char *)(ip + 1);
  89         length = (IP_HL(ip) << 2) - sizeof(struct ip);
  90
  91         for (; length > 0; cp += len, length -= len) {
  92                 int tt = *cp;
  93
  94                 if (tt == IPOPT_NOP || tt == IPOPT_EOL)
  95                         len = 1;
  96                 else {
  97                         if (&cp[1] >= snapend) {
  98                                 return 0;
  99                         }
 100                         len = cp[1];
 101                 }
 102                 if (len <= 0) {
 103                         return 0;
 104                 }
 105                 if (&cp[1] >= snapend || cp + len > snapend) {
 106                         return 0;
 107                 }
 108                 switch (tt) {
 109
 110                 case IPOPT_SSRR:
 111                 case IPOPT_LSRR:
 112                         memcpy(&retval, cp + len - 4, 4);
 113                         return retval;
 114                 }
 115         }
 116         return ip->ip_dst.s_addr;
 117 }
 118
 119 static void
 120 ip_printts(register const u_char *cp, u_int length)
 121 {
 122         register u_int ptr = cp[2] - 1;
 123         register u_int len = 0;
 124         int hoplen;
 125         const char *type;
 126
 127         printf(" TS{");
 128         hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
 129         if ((length - 4) & (hoplen-1))
 130                 printf("[bad length %d]", length);
 131         if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
 132                 printf("[bad ptr %d]", cp[2]);
 133         switch (cp[3]&0xF) {
 134         case IPOPT_TS_TSONLY:
 135                 printf("TSONLY");
 136                 break;
 137         case IPOPT_TS_TSANDADDR:
 138                 printf("TS+ADDR");
 139                 break;
 140         /*
 141          * prespecified should really be 3, but some ones might send 2
 142          * instead, and the IPOPT_TS_PRESPEC constant can apparently
 143          * have both values, so we have to hard-code it here.
 144          */
 145
 146         case 2:
 147                 printf("PRESPEC2.0");
 148                 break;
 149         case 3:                 /* IPOPT_TS_PRESPEC */
 150                 printf("PRESPEC");
 151                 break;
 152         default:
 153                 printf("[bad ts type %d]", cp[3]&0xF);
 154                 goto done;
 155         }
 156
 157         type = " ";
 158         for (len = 4; len < length; len += hoplen) {
 159                 if (ptr == len)
 160                         type = " ^ ";
 161                 printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]),
 162                        hoplen!=8 ? "" : ipaddr_string(&cp[len]));
 163                 type = " ";
 164         }
 165
 166 done:
 167         printf("%s", ptr == len ? " ^ " : "");
 168
 169         if (cp[3]>>4)
 170                 printf(" [%d hops not recorded]} ", cp[3]>>4);
 171         else
 172                 printf("}");
 173 }
 174
 175 /*
 176  * print IP options.
 177  */
 178 static void
 179 ip_optprint(register const u_char *cp, u_int length)
 180 {
 181         register u_int len;
 182
 183         for (; length > 0; cp += len, length -= len) {
 184                 int tt = *cp;
 185
 186                 if (tt == IPOPT_NOP || tt == IPOPT_EOL)
 187                         len = 1;
 188                 else {
 189                         if (&cp[1] >= snapend) {
 190                                 printf("[|ip]");
 191                                 return;
 192                         }
 193                         len = cp[1];
 194                 }
 195                 if (len <= 0) {
 196                         printf("[|ip op len %d]", len);
 197                         return;
 198                 }
 199                 if (&cp[1] >= snapend || cp + len > snapend) {
 200                         printf("[|ip]");
 201                         return;
 202                 }
 203                 switch (tt) {
 204
 205                 case IPOPT_EOL:
 206                         printf(" EOL");
 207                         if (length > 1)
 208                                 printf("-%d", length - 1);
 209                         return;
 210
 211                 case IPOPT_NOP:
 212                         printf(" NOP");
 213                         break;
 214
 215                 case IPOPT_TS:
 216                         ip_printts(cp, len);
 217                         break;
 218
 219 #ifndef IPOPT_SECURITY
 220 #define IPOPT_SECURITY 130
 221 #endif /* IPOPT_SECURITY */
 222                 case IPOPT_SECURITY:
 223                         printf(" SECURITY{%d}", len);
 224                         break;
 225
 226                 case IPOPT_RR:
 227                         ip_printroute("RR", cp, len);
 228                         break;
 229
 230                 case IPOPT_SSRR:
 231                         ip_printroute("SSRR", cp, len);
 232                         break;
 233
 234                 case IPOPT_LSRR:
 235                         ip_printroute("LSRR", cp, len);
 236                         break;
 237
 238 #ifndef IPOPT_RA
 239 #define IPOPT_RA 148            /* router alert */
 240 #endif
 241                 case IPOPT_RA:
 242                         printf(" RA");
 243                         if (len != 4)
 244                                 printf("{%d}", len);
 245                         else if (cp[2] || cp[3])
 246                                 printf("%d.%d", cp[2], cp[3]);
 247                         break;
 248
 249                 default:
 250                         printf(" IPOPT-%d{%d}", cp[0], len);
 251                         break;
 252                 }
 253         }
 254 }
 255
 256 /*
 257  * compute an IP header checksum.
 258  * don't modifiy the packet.
 259  */
 260 u_short
 261 in_cksum(const u_short *addr, register u_int len, int csum)
 262 {
 263         int nleft = len;
 264         const u_short *w = addr;
 265         u_short answer;
 266         int sum = csum;
 267
 268         /*
 269          *  Our algorithm is simple, using a 32 bit accumulator (sum),
 270          *  we add sequential 16 bit words to it, and at the end, fold
 271          *  back all the carry bits from the top 16 bits into the lower
 272          *  16 bits.
 273          */
 274         while (nleft > 1)  {
 275                 sum += *w++;
 276                 nleft -= 2;
 277         }
 278         if (nleft == 1)
 279                 sum += htons(*(u_char *)w<<8);
 280
 281         /*
 282          * add back carry outs from top 16 bits to low 16 bits
 283          */
 284         sum = (sum >> 16) + (sum & 0xffff);     /* add hi 16 to low 16 */
 285         sum += (sum >> 16);                     /* add carry */
 286         answer = ~sum;                          /* truncate to 16 bits */
 287         return (answer);
 288 }
 289
 290 /*
 291  * Given the host-byte-order value of the checksum field in a packet
 292  * header, and the network-byte-order computed checksum of the data
 293  * that the checksum covers (including the checksum itself), compute
 294  * what the checksum field *should* have been.
 295  */
 296 u_int16_t
 297 in_cksum_shouldbe(u_int16_t sum, u_int16_t computed_sum)
 298 {
 299         u_int32_t shouldbe;
 300
 301         /*
 302          * The value that should have gone into the checksum field
 303          * is the negative of the value gotten by summing up everything
 304          * *but* the checksum field.
 305          *
 306          * We can compute that by subtracting the value of the checksum
 307          * field from the sum of all the data in the packet, and then
 308          * computing the negative of that value.
 309          *
 310          * "sum" is the value of the checksum field, and "computed_sum"
 311          * is the negative of the sum of all the data in the packets,
 312          * so that's -(-computed_sum - sum), or (sum + computed_sum).
 313          *
 314          * All the arithmetic in question is one's complement, so the
 315          * addition must include an end-around carry; we do this by
 316          * doing the arithmetic in 32 bits (with no sign-extension),
 317          * and then adding the upper 16 bits of the sum, which contain
 318          * the carry, to the lower 16 bits of the sum, and then do it
 319          * again in case *that* sum produced a carry.
 320          *
 321          * As RFC 1071 notes, the checksum can be computed without
 322          * byte-swapping the 16-bit words; summing 16-bit words
 323          * on a big-endian machine gives a big-endian checksum, which
 324          * can be directly stuffed into the big-endian checksum fields
 325          * in protocol headers, and summing words on a little-endian
 326          * machine gives a little-endian checksum, which must be
 327          * byte-swapped before being stuffed into a big-endian checksum
 328          * field.
 329          *
 330          * "computed_sum" is a network-byte-order value, so we must put
 331          * it in host byte order before subtracting it from the
 332          * host-byte-order value from the header; the adjusted checksum
 333          * will be in host byte order, which is what we'll return.
 334          */
 335         shouldbe = sum;
 336         shouldbe += ntohs(computed_sum);
 337         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 338         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 339         return shouldbe;
 340 }
 341
 342 #ifndef IP_MF
 343 #define IP_MF 0x2000
 344 #endif /* IP_MF */
 345 #ifndef IP_DF
 346 #define IP_DF 0x4000
 347 #endif /* IP_DF */
 348 #define IP_RES 0x8000
 349
 350 static struct tok ip_frag_values[] = {
 351         { IP_MF,        "+" },
 352         { IP_DF,        "DF" },
 353         { IP_RES,       "rsvd" }, /* The RFC3514 evil ;-) bit */
 354         { 0,            NULL }
 355 };
 356
 357 /*
 358  * print an IP datagram.
 359  */
 360 void
 361 ip_print(register const u_char *bp, register u_int length)
 362 {
 363         register const struct ip *ip;
 364         register u_int hlen, len, len0, off;
 365         register const u_char *cp;
 366         u_char nh;
 367         int advance;
 368         struct protoent *proto;
 369         u_int16_t sum, ip_sum;
 370         const char *sep = "";
 371
 372         ip = (const struct ip *)bp;
 373         if (IP_V(ip) != 4) { /* print version if != 4 */
 374             printf("IP%u ", IP_V(ip));
 375             if (IP_V(ip) == 6)
 376                 printf(", wrong link-layer encapsulation");
 377         }
 378         else
 379             printf("IP ");
 380
 381         if ((u_char *)(ip + 1) > snapend) {
 382                 printf("[|ip]");
 383                 return;
 384         }
 385         if (length < sizeof (struct ip)) {
 386                 (void)printf("truncated-ip %d", length);
 387                 return;
 388         }
 389         hlen = IP_HL(ip) * 4;
 390         if (hlen < sizeof (struct ip)) {
 391                 (void)printf("bad-hlen %d", hlen);
 392                 return;
 393         }
 394
 395         len = EXTRACT_16BITS(&ip->ip_len);
 396         if (length < len)
 397                 (void)printf("truncated-ip - %d bytes missing! ",
 398                         len - length);
 399         len -= hlen;
 400         len0 = len;
 401
 402         off = EXTRACT_16BITS(&ip->ip_off);
 403
 404         if (vflag) {
 405             (void)printf("(tos 0x%x", (int)ip->ip_tos);
 406             /* ECN bits */
 407             if (ip->ip_tos & 0x03) {
 408                 switch (ip->ip_tos & 0x03) {
 409                 case 1:
 410                     (void)printf(",ECT(1)");
 411                     break;
 412                 case 2:
 413                     (void)printf(",ECT(0)");
 414                     break;
 415                 case 3:
 416                     (void)printf(",CE");
 417                 }
 418             }
 419
 420             if (ip->ip_ttl >= 1)
 421                 (void)printf(", ttl %3u", ip->ip_ttl);
 422
 423             /*
 424              * for the firewall guys, print id, offset.
 425              * On all but the last stick a "+" in the flags portion.
 426              * For unfragmented datagrams, note the don't fragment flag.
 427              */
 428
 429             (void)printf(", id %u, offset %u, flags [%s]",
 430                              EXTRACT_16BITS(&ip->ip_id),
 431                              (off & 0x1fff) * 8,
 432                              bittok2str(ip_frag_values, "none", off & 0xe000 ));
 433
 434             (void)printf(", length: %u", EXTRACT_16BITS(&ip->ip_len));
 435
 436             if ((hlen - sizeof(struct ip)) > 0) {
 437                 (void)printf(", optlength: %u (", hlen - (u_int)sizeof(struct ip));
 438                 ip_optprint((u_char *)(ip + 1), hlen - sizeof(struct ip));
 439                 printf(" )");
 440             }
 441
 442             if ((u_char *)ip + hlen <= snapend) {
 443                 sum = in_cksum((const u_short *)ip, hlen, 0);
 444                 if (sum != 0) {
 445                     ip_sum = EXTRACT_16BITS(&ip->ip_sum);
 446                     (void)printf("%sbad cksum %x (->%x)!", sep,
 447                              ip_sum,
 448                              in_cksum_shouldbe(ip_sum, sum));
 449                     sep = ", ";
 450                 }
 451             }
 452
 453             printf(") ");
 454         }
 455
 456         /*
 457          * If this is fragment zero, hand it to the next higher
 458          * level protocol.
 459          */
 460         if ((off & 0x1fff) == 0) {
 461                 cp = (const u_char *)ip + hlen;
 462                 nh = ip->ip_p;
 463
 464 #ifndef IPPROTO_SCTP
 465 #define IPPROTO_SCTP 132
 466 #endif
 467                 if (nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 468                     nh != IPPROTO_SCTP) {
 469                         (void)printf("%s > %s: ", ipaddr_string(&ip->ip_src),
 470                                 ipaddr_string(&ip->ip_dst));
 471                 }
 472 again:
 473                 switch (nh) {
 474
 475 #ifndef IPPROTO_AH
 476 #define IPPROTO_AH      51
 477 #endif
 478                 case IPPROTO_AH:
 479                         nh = *cp;
 480                         advance = ah_print(cp);
 481                         cp += advance;
 482                         len -= advance;
 483                         goto again;
 484
 485 #ifndef IPPROTO_ESP
 486 #define IPPROTO_ESP     50
 487 #endif
 488                 case IPPROTO_ESP:
 489                     {
 490                         int enh, padlen;
 491                         advance = esp_print(cp, (const u_char *)ip, &enh, &padlen);
 492                         cp += advance;
 493                         len -= advance + padlen;
 494                         if (enh < 0)
 495                                 break;
 496                         nh = enh & 0xff;
 497                         goto again;
 498                     }
 499
 500 #ifndef IPPROTO_IPCOMP
 501 #define IPPROTO_IPCOMP  108
 502 #endif
 503                 case IPPROTO_IPCOMP:
 504                     {
 505                         int enh;
 506                         advance = ipcomp_print(cp, &enh);
 507                         cp += advance;
 508                         len -= advance;
 509                         if (enh < 0)
 510                                 break;
 511                         nh = enh & 0xff;
 512                         goto again;
 513                     }
 514
 515                 case IPPROTO_SCTP:
 516                         sctp_print(cp, (const u_char *)ip, len);
 517                         break;
 518
 519                 case IPPROTO_TCP:
 520                         tcp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 521                         break;
 522
 523                 case IPPROTO_UDP:
 524                         udp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 525                         break;
 526
 527                 case IPPROTO_ICMP:
 528                         /* pass on the MF bit plus the offset to detect fragments */
 529                         icmp_print(cp, len, (const u_char *)ip, (off & 0x3fff));
 530                         break;
 531
 532 #ifndef IPPROTO_IGRP
 533 #define IPPROTO_IGRP 9
 534 #endif
 535                 case IPPROTO_IGRP:
 536                         igrp_print(cp, len, (const u_char *)ip);
 537                         break;
 538
 539                 case IPPROTO_ND:
 540                         (void)printf(" nd %d", len);
 541                         break;
 542
 543                 case IPPROTO_EGP:
 544                         egp_print(cp);
 545                         break;
 546
 547 #ifndef IPPROTO_OSPF
 548 #define IPPROTO_OSPF 89
 549 #endif
 550                 case IPPROTO_OSPF:
 551                         ospf_print(cp, len, (const u_char *)ip);
 552                         break;
 553
 554 #ifndef IPPROTO_IGMP
 555 #define IPPROTO_IGMP 2
 556 #endif
 557                 case IPPROTO_IGMP:
 558                         igmp_print(cp, len);
 559                         break;
 560
 561                 case 4:
 562                         /* DVMRP multicast tunnel (ip-in-ip encapsulation) */
 563                         ip_print(cp, len);
 564                         if (! vflag) {
 565                                 printf(" (ipip-proto-4)");
 566                                 return;
 567                         }
 568                         break;
 569
 570 #ifdef INET6
 571 #ifndef IP6PROTO_ENCAP
 572 #define IP6PROTO_ENCAP 41
 573 #endif
 574                 case IP6PROTO_ENCAP:
 575                         /* ip6-in-ip encapsulation */
 576                         ip6_print(cp, len);
 577                         break;
 578 #endif /*INET6*/
 579
 580 #ifndef IPPROTO_RSVP
 581 #define IPPROTO_RSVP 46
 582 #endif
 583                 case IPPROTO_RSVP:
 584                         rsvp_print(cp, len);
 585                         break;
 586
 587 #ifndef IPPROTO_GRE
 588 #define IPPROTO_GRE 47
 589 #endif
 590                 case IPPROTO_GRE:
 591                         /* do it */
 592                         gre_print(cp, len);
 593                         break;
 594
 595 #ifndef IPPROTO_MOBILE
 596 #define IPPROTO_MOBILE 55
 597 #endif
 598                 case IPPROTO_MOBILE:
 599                         mobile_print(cp, len);
 600                         break;
 601
 602 #ifndef IPPROTO_PIM
 603 #define IPPROTO_PIM     103
 604 #endif
 605                 case IPPROTO_PIM:
 606                         pim_print(cp, len);
 607                         break;
 608
 609 #ifndef IPPROTO_VRRP
 610 #define IPPROTO_VRRP    112
 611 #endif
 612                 case IPPROTO_VRRP:
 613                         vrrp_print(cp, len, ip->ip_ttl);
 614                         break;
 615
 616                 default:
 617                         if ((proto = getprotobynumber(nh)) != NULL)
 618                                 (void)printf(" %s", proto->p_name);
 619                         else
 620                                 (void)printf(" ip-proto-%d", nh);
 621                         printf(" %d", len);
 622                         break;
 623                 }
 624         } else {
 625             /* Ultra quiet now means that all this stuff should be suppressed */
 626             if (qflag > 1) return;
 627
 628             /*
 629              * if this isn't the first frag, we're missing the
 630              * next level protocol header.  print the ip addr
 631              * and the protocol.
 632              */
 633             if (off & 0x1fff) {
 634                 (void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
 635                              ipaddr_string(&ip->ip_dst));
 636                 if ((proto = getprotobynumber(ip->ip_p)) != NULL)
 637                     (void)printf(" %s", proto->p_name);
 638                 else
 639                     (void)printf(" ip-proto-%d", ip->ip_p);
 640             }
 641         }
 642 }
 643
 644 void
 645 ipN_print(register const u_char *bp, register u_int length)
 646 {
 647         struct ip *ip, hdr;
 648
 649         ip = (struct ip *)bp;
 650         if (length < 4) {
 651                 (void)printf("truncated-ip %d", length);
 652                 return;
 653         }
 654         memcpy (&hdr, (char *)ip, 4);
 655         switch (IP_V(&hdr)) {
 656         case 4:
 657                 ip_print (bp, length);
 658                 return;
 659 #ifdef INET6
 660         case 6:
 661                 ip6_print (bp, length);
 662                 return;
 663 #endif
 664         default:
 665                 (void)printf("unknown ip %d", IP_V(&hdr));
 666                 return;
 667         }
 668 }
 669
 670
 671