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 1.109 2002-07-21 20:48:26 guy 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 static void
  80 ip_printts(register const u_char *cp, u_int length)
  81 {
  82         register u_int ptr = cp[2] - 1;
  83         register u_int len = 0;
  84         int hoplen;
  85         char *type;
  86
  87         printf(" TS{");
  88         hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
  89         if ((length - 4) & (hoplen-1))
  90                 printf("[bad length %d]", length);
  91         if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
  92                 printf("[bad ptr %d]", cp[2]);
  93         switch (cp[3]&0xF) {
  94         case IPOPT_TS_TSONLY:
  95                 printf("TSONLY");
  96                 break;
  97         case IPOPT_TS_TSANDADDR:
  98                 printf("TS+ADDR");
  99                 break;
 100         /*
 101          * prespecified should really be 3, but some ones might send 2
 102          * instead, and the IPOPT_TS_PRESPEC constant can apparently
 103          * have both values, so we have to hard-code it here.
 104          */
 105
 106         case 2:
 107                 printf("PRESPEC2.0");
 108                 break;
 109         case 3:                 /* IPOPT_TS_PRESPEC */
 110                 printf("PRESPEC");
 111                 break;
 112         default:
 113                 printf("[bad ts type %d]", cp[3]&0xF);
 114                 goto done;
 115         }
 116
 117         type = " ";
 118         for (len = 4; len < length; len += hoplen) {
 119                 if (ptr == len)
 120                         type = " ^ ";
 121                 printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]),
 122                        hoplen!=8 ? "" : ipaddr_string(&cp[len]));
 123                 type = " ";
 124         }
 125
 126 done:
 127         printf("%s", ptr == len ? " ^ " : "");
 128
 129         if (cp[3]>>4)
 130                 printf(" [%d hops not recorded]} ", cp[3]>>4);
 131         else
 132                 printf("}");
 133 }
 134
 135 /*
 136  * print IP options.
 137  */
 138 static void
 139 ip_optprint(register const u_char *cp, u_int length)
 140 {
 141         register u_int len;
 142
 143         for (; length > 0; cp += len, length -= len) {
 144                 int tt = *cp;
 145
 146                 if (tt == IPOPT_NOP || tt == IPOPT_EOL)
 147                         len = 1;
 148                 else {
 149                         if (&cp[1] >= snapend) {
 150                                 printf("[|ip]");
 151                                 return;
 152                         }
 153                         len = cp[1];
 154                 }
 155                 if (len <= 0) {
 156                         printf("[|ip op len %d]", len);
 157                         return;
 158                 }
 159                 if (&cp[1] >= snapend || cp + len > snapend) {
 160                         printf("[|ip]");
 161                         return;
 162                 }
 163                 switch (tt) {
 164
 165                 case IPOPT_EOL:
 166                         printf(" EOL");
 167                         if (length > 1)
 168                                 printf("-%d", length - 1);
 169                         return;
 170
 171                 case IPOPT_NOP:
 172                         printf(" NOP");
 173                         break;
 174
 175                 case IPOPT_TS:
 176                         ip_printts(cp, len);
 177                         break;
 178
 179 #ifndef IPOPT_SECURITY
 180 #define IPOPT_SECURITY 130
 181 #endif /* IPOPT_SECURITY */
 182                 case IPOPT_SECURITY:
 183                         printf(" SECURITY{%d}", len);
 184                         break;
 185
 186                 case IPOPT_RR:
 187                         ip_printroute("RR", cp, len);
 188                         break;
 189
 190                 case IPOPT_SSRR:
 191                         ip_printroute("SSRR", cp, len);
 192                         break;
 193
 194                 case IPOPT_LSRR:
 195                         ip_printroute("LSRR", cp, len);
 196                         break;
 197
 198 #ifndef IPOPT_RA
 199 #define IPOPT_RA 148            /* router alert */
 200 #endif
 201                 case IPOPT_RA:
 202                         printf(" RA");
 203                         if (len != 4)
 204                                 printf("{%d}", len);
 205                         else if (cp[2] || cp[3])
 206                                 printf("%d.%d", cp[2], cp[3]);
 207                         break;
 208
 209                 default:
 210                         printf(" IPOPT-%d{%d}", cp[0], len);
 211                         break;
 212                 }
 213         }
 214 }
 215
 216 /*
 217  * compute an IP header checksum.
 218  * don't modifiy the packet.
 219  */
 220 u_short
 221 in_cksum(const u_short *addr, register u_int len, int csum)
 222 {
 223         int nleft = len;
 224         const u_short *w = addr;
 225         u_short answer;
 226         int sum = csum;
 227
 228         /*
 229          *  Our algorithm is simple, using a 32 bit accumulator (sum),
 230          *  we add sequential 16 bit words to it, and at the end, fold
 231          *  back all the carry bits from the top 16 bits into the lower
 232          *  16 bits.
 233          */
 234         while (nleft > 1)  {
 235                 sum += *w++;
 236                 nleft -= 2;
 237         }
 238         if (nleft == 1)
 239                 sum += htons(*(u_char *)w<<8);
 240
 241         /*
 242          * add back carry outs from top 16 bits to low 16 bits
 243          */
 244         sum = (sum >> 16) + (sum & 0xffff);     /* add hi 16 to low 16 */
 245         sum += (sum >> 16);                     /* add carry */
 246         answer = ~sum;                          /* truncate to 16 bits */
 247         return (answer);
 248 }
 249
 250 /*
 251  * Given the host-byte-order value of the checksum field in a packet
 252  * header, and the network-byte-order computed checksum of the data
 253  * that the checksum covers (including the checksum itself), compute
 254  * what the checksum field *should* have been.
 255  */
 256 u_int16_t
 257 in_cksum_shouldbe(u_int16_t sum, u_int16_t computed_sum)
 258 {
 259         u_int32_t shouldbe;
 260
 261         /*
 262          * The value that should have gone into the checksum field
 263          * is the negative of the value gotten by summing up everything
 264          * *but* the checksum field.
 265          *
 266          * We can compute that by subtracting the value of the checksum
 267          * field from the sum of all the data in the packet, and then
 268          * computing the negative of that value.
 269          *
 270          * "sum" is the value of the checksum field, and "computed_sum"
 271          * is the negative of the sum of all the data in the packets,
 272          * so that's -(-computed_sum - sum), or (sum + computed_sum).
 273          *
 274          * All the arithmetic in question is one's complement, so the
 275          * addition must include an end-around carry; we do this by
 276          * doing the arithmetic in 32 bits (with no sign-extension),
 277          * and then adding the upper 16 bits of the sum, which contain
 278          * the carry, to the lower 16 bits of the sum, and then do it
 279          * again in case *that* sum produced a carry.
 280          *
 281          * As RFC 1071 notes, the checksum can be computed without
 282          * byte-swapping the 16-bit words; summing 16-bit words
 283          * on a big-endian machine gives a big-endian checksum, which
 284          * can be directly stuffed into the big-endian checksum fields
 285          * in protocol headers, and summing words on a little-endian
 286          * machine gives a little-endian checksum, which must be
 287          * byte-swapped before being stuffed into a big-endian checksum
 288          * field.
 289          *
 290          * "computed_sum" is a network-byte-order value, so we must put
 291          * it in host byte order before subtracting it from the
 292          * host-byte-order value from the header; the adjusted checksum
 293          * will be in host byte order, which is what we'll return.
 294          */
 295         shouldbe = sum;
 296         shouldbe += ntohs(computed_sum);
 297         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 298         shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16);
 299         return shouldbe;
 300 }
 301
 302 /*
 303  * print an IP datagram.
 304  */
 305 void
 306 ip_print(register const u_char *bp, register u_int length)
 307 {
 308         register const struct ip *ip;
 309         register u_int hlen, len, len0, off;
 310         register const u_char *cp;
 311         u_char nh;
 312         int advance;
 313         struct protoent *proto;
 314
 315         ip = (const struct ip *)bp;
 316 #ifdef LBL_ALIGN
 317         /*
 318          * If the IP header is not aligned, copy into abuf.
 319          */
 320         if ((long)ip & 3) {
 321                 static u_char *abuf = NULL;
 322                 static int didwarn = 0;
 323
 324                 if (abuf == NULL) {
 325                         abuf = (u_char *)malloc(snaplen);
 326                         if (abuf == NULL)
 327                                 error("ip_print: malloc");
 328                 }
 329                 memcpy((char *)abuf, (char *)ip, min(length, snaplen));
 330                 snapend += abuf - (u_char *)ip;
 331                 packetp = abuf;
 332                 ip = (struct ip *)abuf;
 333                 /* We really want libpcap to give us aligned packets */
 334                 if (!didwarn) {
 335                         warning("compensating for unaligned libpcap packets");
 336                         ++didwarn;
 337                 }
 338         }
 339 #endif
 340         if ((u_char *)(ip + 1) > snapend) {
 341                 printf("[|ip]");
 342                 return;
 343         }
 344         if (length < sizeof (struct ip)) {
 345                 (void)printf("truncated-ip %d", length);
 346                 return;
 347         }
 348         hlen = IP_HL(ip) * 4;
 349         if (hlen < sizeof (struct ip)) {
 350                 (void)printf("bad-hlen %d", hlen);
 351                 return;
 352         }
 353
 354         len = ntohs(ip->ip_len);
 355         if (length < len)
 356                 (void)printf("truncated-ip - %d bytes missing! ",
 357                         len - length);
 358         len -= hlen;
 359         len0 = len;
 360
 361         printf("IP ");
 362
 363         off = ntohs(ip->ip_off);
 364
 365         if (vflag) {
 366             (void)printf("(tos 0x%x", (int)ip->ip_tos);
 367             /* ECN bits */
 368             if (ip->ip_tos & 0x03) {
 369                 switch (ip->ip_tos & 0x03) {
 370                 case 1:
 371                     (void)printf(",ECT(1)");
 372                     break;
 373                 case 2:
 374                     (void)printf(",ECT(0)");
 375                     break;
 376                 case 3:
 377                     (void)printf(",CE");
 378                 }
 379             }
 380
 381             if (ip->ip_ttl >= 1)
 382                 (void)printf(", ttl %d", (int)ip->ip_ttl);
 383
 384             if ((off & 0x3fff) == 0)
 385                 (void)printf(", id %d", (int)ntohs(ip->ip_id));
 386             (void)printf(", len %d) ", (int)ntohs(ip->ip_len));
 387         }
 388
 389         /*
 390          * If this is fragment zero, hand it to the next higher
 391          * level protocol.
 392          */
 393         if ((off & 0x1fff) == 0) {
 394                 cp = (const u_char *)ip + hlen;
 395                 nh = ip->ip_p;
 396
 397 #ifndef IPPROTO_SCTP
 398 #define IPPROTO_SCTP 132
 399 #endif
 400                 if (nh != IPPROTO_TCP && nh != IPPROTO_UDP &&
 401                     nh != IPPROTO_SCTP) {
 402                         (void)printf("%s > %s: ", ipaddr_string(&ip->ip_src),
 403                                 ipaddr_string(&ip->ip_dst));
 404                 }
 405 again:
 406                 switch (nh) {
 407
 408 #ifndef IPPROTO_AH
 409 #define IPPROTO_AH      51
 410 #endif
 411                 case IPPROTO_AH:
 412                         nh = *cp;
 413                         advance = ah_print(cp, (const u_char *)ip);
 414                         cp += advance;
 415                         len -= advance;
 416                         goto again;
 417
 418 #ifndef IPPROTO_ESP
 419 #define IPPROTO_ESP     50
 420 #endif
 421                 case IPPROTO_ESP:
 422                     {
 423                         int enh, padlen;
 424                         advance = esp_print(cp, (const u_char *)ip, &enh, &padlen);
 425                         cp += advance;
 426                         len -= advance + padlen;
 427                         if (enh < 0)
 428                                 break;
 429                         nh = enh & 0xff;
 430                         goto again;
 431                     }
 432
 433 #ifndef IPPROTO_IPCOMP
 434 #define IPPROTO_IPCOMP  108
 435 #endif
 436                 case IPPROTO_IPCOMP:
 437                     {
 438                         int enh;
 439                         advance = ipcomp_print(cp, (const u_char *)ip, &enh);
 440                         cp += advance;
 441                         len -= advance;
 442                         if (enh < 0)
 443                                 break;
 444                         nh = enh & 0xff;
 445                         goto again;
 446                     }
 447
 448                 case IPPROTO_SCTP:
 449                         sctp_print(cp, (const u_char *)ip, len);
 450                         break;
 451
 452                 case IPPROTO_TCP:
 453                         tcp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 454                         break;
 455
 456                 case IPPROTO_UDP:
 457                         udp_print(cp, len, (const u_char *)ip, (off &~ 0x6000));
 458                         break;
 459
 460                 case IPPROTO_ICMP:
 461                         icmp_print(cp, len, (const u_char *)ip);
 462                         break;
 463
 464 #ifndef IPPROTO_IGRP
 465 #define IPPROTO_IGRP 9
 466 #endif
 467                 case IPPROTO_IGRP:
 468                         igrp_print(cp, len, (const u_char *)ip);
 469                         break;
 470
 471                 case IPPROTO_ND:
 472                         (void)printf(" nd %d", len);
 473                         break;
 474
 475                 case IPPROTO_EGP:
 476                         egp_print(cp, len, (const u_char *)ip);
 477                         break;
 478
 479 #ifndef IPPROTO_OSPF
 480 #define IPPROTO_OSPF 89
 481 #endif
 482                 case IPPROTO_OSPF:
 483                         ospf_print(cp, len, (const u_char *)ip);
 484                         break;
 485
 486 #ifndef IPPROTO_IGMP
 487 #define IPPROTO_IGMP 2
 488 #endif
 489                 case IPPROTO_IGMP:
 490                         igmp_print(cp, len);
 491                         break;
 492
 493                 case 4:
 494                         /* DVMRP multicast tunnel (ip-in-ip encapsulation) */
 495                         ip_print(cp, len);
 496                         if (! vflag) {
 497                                 printf(" (ipip-proto-4)");
 498                                 return;
 499                         }
 500                         break;
 501
 502 #ifdef INET6
 503 #ifndef IP6PROTO_ENCAP
 504 #define IP6PROTO_ENCAP 41
 505 #endif
 506                 case IP6PROTO_ENCAP:
 507                         /* ip6-in-ip encapsulation */
 508                         ip6_print(cp, len);
 509                         break;
 510 #endif /*INET6*/
 511
 512
 513 #ifndef IPPROTO_GRE
 514 #define IPPROTO_GRE 47
 515 #endif
 516                 case IPPROTO_GRE:
 517                         /* do it */
 518                         gre_print(cp, len);
 519                         break;
 520
 521 #ifndef IPPROTO_MOBILE
 522 #define IPPROTO_MOBILE 55
 523 #endif
 524                 case IPPROTO_MOBILE:
 525                         mobile_print(cp, len);
 526                         break;
 527
 528 #ifndef IPPROTO_PIM
 529 #define IPPROTO_PIM     103
 530 #endif
 531                 case IPPROTO_PIM:
 532                         pim_print(cp, len);
 533                         break;
 534
 535 #ifndef IPPROTO_VRRP
 536 #define IPPROTO_VRRP    112
 537 #endif
 538                 case IPPROTO_VRRP:
 539                         vrrp_print(cp, len, ip->ip_ttl);
 540                         break;
 541
 542                 default:
 543                         if ((proto = getprotobynumber(nh)) != NULL)
 544                                 (void)printf(" %s", proto->p_name);
 545                         else
 546                                 (void)printf(" ip-proto-%d", nh);
 547                         printf(" %d", len);
 548                         break;
 549                 }
 550         }
 551
 552         /* Ultra quiet now means that all this stuff should be suppressed */
 553         /* res 3-Nov-98 */
 554         if (qflag > 1) return;
 555
 556
 557         /*
 558          * for fragmented datagrams, print id:size@offset.  On all
 559          * but the last stick a "+".  For unfragmented datagrams, note
 560          * the don't fragment flag.
 561          */
 562         len = len0;     /* get the original length */
 563         if (off & 0x3fff) {
 564                 /*
 565                  * if this isn't the first frag, we're missing the
 566                  * next level protocol header.  print the ip addr
 567                  * and the protocol.
 568                  */
 569                 if (off & 0x1fff) {
 570                         (void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
 571                                       ipaddr_string(&ip->ip_dst));
 572                         if ((proto = getprotobynumber(ip->ip_p)) != NULL)
 573                                 (void)printf(" %s", proto->p_name);
 574                         else
 575                                 (void)printf(" ip-proto-%d", ip->ip_p);
 576                 }
 577 #ifndef IP_MF
 578 #define IP_MF 0x2000
 579 #endif /* IP_MF */
 580 #ifndef IP_DF
 581 #define IP_DF 0x4000
 582 #endif /* IP_DF */
 583                 (void)printf(" (frag %d:%u@%d%s)", ntohs(ip->ip_id), len,
 584                         (off & 0x1fff) * 8,
 585                         (off & IP_MF)? "+" : "");
 586
 587         } else if (off & IP_DF)
 588                 (void)printf(" (DF)");
 589
 590         if (vflag) {
 591                 u_int16_t sum, ip_sum;
 592                 char *sep = "";
 593
 594                 if ((u_char *)ip + hlen <= snapend) {
 595                         sum = in_cksum((const u_short *)ip, hlen, 0);
 596                         if (sum != 0) {
 597                                 ip_sum = ntohs(ip->ip_sum);
 598                                 (void)printf("%sbad cksum %x (->%x)!", sep,
 599                                              ip_sum,
 600                                              in_cksum_shouldbe(ip_sum, sum));
 601                                 sep = ", ";
 602                         }
 603                 }
 604                 if ((hlen -= sizeof(struct ip)) > 0) {
 605                         (void)printf("%soptlen=%d", sep, hlen);
 606                         ip_optprint((u_char *)(ip + 1), hlen);
 607                 }
 608         }
 609
 610 }
 611
 612 void
 613 ipN_print(register const u_char *bp, register u_int length)
 614 {
 615         struct ip *ip, hdr;
 616
 617         ip = (struct ip *)bp;
 618         if (length < 4) {
 619                 (void)printf("truncated-ip %d", length);
 620                 return;
 621         }
 622         memcpy (&hdr, (char *)ip, 4);
 623         switch (IP_V(&hdr)) {
 624         case 4:
 625                 ip_print (bp, length);
 626                 return;
 627 #ifdef INET6
 628         case 6:
 629                 ip6_print (bp, length);
 630                 return;
 631 #endif
 632         default:
 633                 (void)printf("unknown ip %d", IP_V(&hdr));
 634                 return;
 635         }
 636 }
 637
 638