The Tcpdump Group git mirrors - tcpdump/blob - print-tcp.c

   1 /*      $NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky Exp $     */
   2
   3 /*
   4  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Copyright (c) 1999-2004 The tcpdump.org project
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that: (1) source code distributions
  11  * retain the above copyright notice and this paragraph in its entirety, (2)
  12  * distributions including binary code include the above copyright notice and
  13  * this paragraph in its entirety in the documentation or other materials
  14  * provided with the distribution, and (3) all advertising materials mentioning
  15  * features or use of this software display the following acknowledgement:
  16  * ``This product includes software developed by the University of California,
  17  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  18  * the University nor the names of its contributors may be used to endorse
  19  * or promote products derived from this software without specific prior
  20  * written permission.
  21  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  22  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  23  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  24  */
  25
  26 #ifndef lint
  27 static const char rcsid[] _U_ =
  28 "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.135 2008-11-09 23:35:03 mcr Exp $ (LBL)";
  29 #else
  30 __RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $");
  31 #endif
  32
  33 #ifdef HAVE_CONFIG_H
  34 #include "config.h"
  35 #endif
  36
  37 #include <tcpdump-stdinc.h>
  38
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #include "interface.h"
  44 #include "addrtoname.h"
  45 #include "extract.h"
  46
  47 #include "tcp.h"
  48
  49 #include "ip.h"
  50 #ifdef INET6
  51 #include "ip6.h"
  52 #endif
  53 #include "ipproto.h"
  54 #include "rpc_auth.h"
  55 #include "rpc_msg.h"
  56
  57 #include "nameser.h"
  58
  59 #ifdef HAVE_LIBCRYPTO
  60 #include <openssl/md5.h>
  61 #include <signature.h>
  62
  63 static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
  64                                 const u_char *data, int length, const u_char *rcvsig);
  65 #endif
  66
  67 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  68
  69 #define MAX_RST_DATA_LEN        30
  70
  71
  72 struct tha {
  73 #ifndef INET6
  74         struct in_addr src;
  75         struct in_addr dst;
  76 #else
  77         struct in6_addr src;
  78         struct in6_addr dst;
  79 #endif /*INET6*/
  80         u_int port;
  81 };
  82
  83 struct tcp_seq_hash {
  84         struct tcp_seq_hash *nxt;
  85         struct tha addr;
  86         tcp_seq seq;
  87         tcp_seq ack;
  88 };
  89
  90 #define TSEQ_HASHSIZE 919
  91
  92 /* These tcp optinos do not have the size octet */
  93 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
  94
  95 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
  96
  97 struct tok tcp_flag_values[] = {
  98         { TH_FIN, "F" },
  99         { TH_SYN, "S" },
 100         { TH_RST, "R" },
 101         { TH_PUSH, "P" },
 102         { TH_ACK, "." },
 103         { TH_URG, "U" },
 104         { TH_ECNECHO, "E" },
 105         { TH_CWR, "W" },
 106         { 0, NULL }
 107 };
 108
 109 struct tok tcp_option_values[] = {
 110         { TCPOPT_EOL, "eol" },
 111         { TCPOPT_NOP, "nop" },
 112         { TCPOPT_MAXSEG, "mss" },
 113         { TCPOPT_WSCALE, "wscale" },
 114         { TCPOPT_SACKOK, "sackOK" },
 115         { TCPOPT_SACK, "sack" },
 116         { TCPOPT_ECHO, "echo" },
 117         { TCPOPT_ECHOREPLY, "echoreply" },
 118         { TCPOPT_TIMESTAMP, "TS" },
 119         { TCPOPT_CC, "cc" },
 120         { TCPOPT_CCNEW, "ccnew" },
 121         { TCPOPT_CCECHO, "" },
 122         { TCPOPT_SIGNATURE, "md5" },
 123         { TCPOPT_AUTH, "enhanced auth" },
 124         { TCPOPT_UTO, "uto" },
 125         { 0, NULL }
 126 };
 127
 128 static int tcp_cksum(register const struct ip *ip,
 129                      register const struct tcphdr *tp,
 130                      register u_int len)
 131 {
 132         union phu {
 133                 struct phdr {
 134                         u_int32_t src;
 135                         u_int32_t dst;
 136                         u_char mbz;
 137                         u_char proto;
 138                         u_int16_t len;
 139                 } ph;
 140                 u_int16_t pa[6];
 141         } phu;
 142         const u_int16_t *sp;
 143
 144         /* pseudo-header.. */
 145         phu.ph.len = htons((u_int16_t)len);
 146         phu.ph.mbz = 0;
 147         phu.ph.proto = IPPROTO_TCP;
 148         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 149         if (IP_HL(ip) == 5)
 150                 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 151         else
 152                 phu.ph.dst = ip_finddst(ip);
 153
 154         sp = &phu.pa[0];
 155         return in_cksum((u_short *)tp, len,
 156                         sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
 157 }
 158
 159 #ifdef INET6
 160 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 161                       u_int len)
 162 {
 163         size_t i;
 164         u_int32_t sum = 0;
 165         union {
 166                 struct {
 167                         struct in6_addr ph_src;
 168                         struct in6_addr ph_dst;
 169                         u_int32_t       ph_len;
 170                         u_int8_t        ph_zero[3];
 171                         u_int8_t        ph_nxt;
 172                 } ph;
 173                 u_int16_t pa[20];
 174         } phu;
 175
 176         /* pseudo-header */
 177         memset(&phu, 0, sizeof(phu));
 178         phu.ph.ph_src = ip6->ip6_src;
 179         phu.ph.ph_dst = ip6->ip6_dst;
 180         phu.ph.ph_len = htonl(len);
 181         phu.ph.ph_nxt = IPPROTO_TCP;
 182
 183         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 184                 sum += phu.pa[i];
 185
 186         return in_cksum((u_short *)tp, len, sum);
 187 }
 188 #endif
 189
 190 void
 191 tcp_print(register const u_char *bp, register u_int length,
 192           register const u_char *bp2, int fragmented)
 193 {
 194         register const struct tcphdr *tp;
 195         register const struct ip *ip;
 196         register u_char flags;
 197         register u_int hlen;
 198         register char ch;
 199         u_int16_t sport, dport, win, urp;
 200         u_int32_t seq, ack, thseq, thack;
 201         int threv;
 202 #ifdef INET6
 203         register const struct ip6_hdr *ip6;
 204 #endif
 205
 206         tp = (struct tcphdr *)bp;
 207         ip = (struct ip *)bp2;
 208 #ifdef INET6
 209         if (IP_V(ip) == 6)
 210                 ip6 = (struct ip6_hdr *)bp2;
 211         else
 212                 ip6 = NULL;
 213 #endif /*INET6*/
 214         ch = '\0';
 215         if (!TTEST(tp->th_dport)) {
 216                 (void)printf("%s > %s: [|tcp]",
 217                              ipaddr_string(&ip->ip_src),
 218                              ipaddr_string(&ip->ip_dst));
 219                 return;
 220         }
 221
 222         sport = EXTRACT_16BITS(&tp->th_sport);
 223         dport = EXTRACT_16BITS(&tp->th_dport);
 224
 225         hlen = TH_OFF(tp) * 4;
 226
 227         /*
 228          * If data present, header length valid, and NFS port used,
 229          * assume NFS.
 230          * Pass offset of data plus 4 bytes for RPC TCP msg length
 231          * to NFS print routines.
 232          */
 233         if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
 234             (length - hlen) >= 4) {
 235                 u_char *fraglenp;
 236                 u_int32_t fraglen;
 237                 register struct sunrpc_msg *rp;
 238                 enum sunrpc_msg_type direction;
 239
 240                 fraglenp = (u_char *)tp + hlen;
 241                 if (TTEST2(*fraglenp, 4)) {
 242                         fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
 243                         if (fraglen > (length - hlen) - 4)
 244                                 fraglen = (length - hlen) - 4;
 245                         rp = (struct sunrpc_msg *)(fraglenp + 4);
 246                         if (TTEST(rp->rm_direction)) {
 247                                 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
 248                                 if (dport == NFS_PORT &&
 249                                     direction == SUNRPC_CALL) {
 250                                         nfsreq_print((u_char *)rp, fraglen,
 251                                             (u_char *)ip);
 252                                         return;
 253                                 }
 254                                 if (sport == NFS_PORT &&
 255                                     direction == SUNRPC_REPLY) {
 256                                         nfsreply_print((u_char *)rp, fraglen,
 257                                             (u_char *)ip);
 258                                         return;
 259                                 }
 260                         }
 261                 }
 262         }
 263 #ifdef INET6
 264         if (ip6) {
 265                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 266                         (void)printf("%s.%s > %s.%s: ",
 267                                      ip6addr_string(&ip6->ip6_src),
 268                                      tcpport_string(sport),
 269                                      ip6addr_string(&ip6->ip6_dst),
 270                                      tcpport_string(dport));
 271                 } else {
 272                         (void)printf("%s > %s: ",
 273                                      tcpport_string(sport), tcpport_string(dport));
 274                 }
 275         } else
 276 #endif /*INET6*/
 277         {
 278                 if (ip->ip_p == IPPROTO_TCP) {
 279                         (void)printf("%s.%s > %s.%s: ",
 280                                      ipaddr_string(&ip->ip_src),
 281                                      tcpport_string(sport),
 282                                      ipaddr_string(&ip->ip_dst),
 283                                      tcpport_string(dport));
 284                 } else {
 285                         (void)printf("%s > %s: ",
 286                                      tcpport_string(sport), tcpport_string(dport));
 287                 }
 288         }
 289
 290         if (hlen < sizeof(*tp)) {
 291                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 292                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 293                 return;
 294         }
 295
 296         TCHECK(*tp);
 297
 298         seq = EXTRACT_32BITS(&tp->th_seq);
 299         ack = EXTRACT_32BITS(&tp->th_ack);
 300         win = EXTRACT_16BITS(&tp->th_win);
 301         urp = EXTRACT_16BITS(&tp->th_urp);
 302
 303         if (qflag) {
 304                 (void)printf("tcp %d", length - hlen);
 305                 if (hlen > length) {
 306                         (void)printf(" [bad hdr length %u - too long, > %u]",
 307                                      hlen, length);
 308                 }
 309                 return;
 310         }
 311
 312         flags = tp->th_flags;
 313         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 314
 315         if (!Sflag && (flags & TH_ACK)) {
 316                 register struct tcp_seq_hash *th;
 317                 const void *src, *dst;
 318                 register int rev;
 319                 struct tha tha;
 320                 /*
 321                  * Find (or record) the initial sequence numbers for
 322                  * this conversation.  (we pick an arbitrary
 323                  * collating order so there's only one entry for
 324                  * both directions).
 325                  */
 326 #ifdef INET6
 327                 memset(&tha, 0, sizeof(tha));
 328                 rev = 0;
 329                 if (ip6) {
 330                         src = &ip6->ip6_src;
 331                         dst = &ip6->ip6_dst;
 332                         if (sport > dport)
 333                                 rev = 1;
 334                         else if (sport == dport) {
 335                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 336                                         rev = 1;
 337                         }
 338                         if (rev) {
 339                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 340                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 341                                 tha.port = dport << 16 | sport;
 342                         } else {
 343                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 344                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 345                                 tha.port = sport << 16 | dport;
 346                         }
 347                 } else {
 348                         src = &ip->ip_src;
 349                         dst = &ip->ip_dst;
 350                         if (sport > dport)
 351                                 rev = 1;
 352                         else if (sport == dport) {
 353                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 354                                         rev = 1;
 355                         }
 356                         if (rev) {
 357                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 358                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 359                                 tha.port = dport << 16 | sport;
 360                         } else {
 361                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 362                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 363                                 tha.port = sport << 16 | dport;
 364                         }
 365                 }
 366 #else
 367                 rev = 0;
 368                 src = &ip->ip_src;
 369                 dst = &ip->ip_dst;
 370                 if (sport > dport)
 371                         rev = 1;
 372                 else if (sport == dport) {
 373                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 374                                 rev = 1;
 375                 }
 376                 if (rev) {
 377                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 378                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 379                         tha.port = dport << 16 | sport;
 380                 } else {
 381                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 382                         memcpy(&tha.src, src, sizeof ip->ip_src);
 383                         tha.port = sport << 16 | dport;
 384                 }
 385 #endif
 386
 387                 threv = rev;
 388                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 389                      th->nxt; th = th->nxt)
 390                         if (memcmp((char *)&tha, (char *)&th->addr,
 391                                    sizeof(th->addr)) == 0)
 392                                 break;
 393
 394                 if (!th->nxt || (flags & TH_SYN)) {
 395                         /* didn't find it or new conversation */
 396                         if (th->nxt == NULL) {
 397                                 th->nxt = (struct tcp_seq_hash *)
 398                                         calloc(1, sizeof(*th));
 399                                 if (th->nxt == NULL)
 400                                         error("tcp_print: calloc");
 401                         }
 402                         th->addr = tha;
 403                         if (rev)
 404                                 th->ack = seq, th->seq = ack - 1;
 405                         else
 406                                 th->seq = seq, th->ack = ack - 1;
 407                 } else {
 408                         if (rev)
 409                                 seq -= th->ack, ack -= th->seq;
 410                         else
 411                                 seq -= th->seq, ack -= th->ack;
 412                 }
 413
 414                 thseq = th->seq;
 415                 thack = th->ack;
 416         } else {
 417                 /*fool gcc*/
 418                 thseq = thack = threv = 0;
 419         }
 420         if (hlen > length) {
 421                 (void)printf(" [bad hdr length %u - too long, > %u]",
 422                              hlen, length);
 423                 return;
 424         }
 425
 426         if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 427                 u_int16_t sum, tcp_sum;
 428                 if (TTEST2(tp->th_sport, length)) {
 429                         sum = tcp_cksum(ip, tp, length);
 430
 431                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 432                         if (sum != 0) {
 433                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 434                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 435                         } else
 436                                 (void)printf(" (correct)");
 437                 }
 438         }
 439 #ifdef INET6
 440         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 441                 u_int16_t sum,tcp_sum;
 442                 if (TTEST2(tp->th_sport, length)) {
 443                         sum = tcp6_cksum(ip6, tp, length);
 444                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 445                         if (sum != 0) {
 446                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 447                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 448                         } else
 449                                 (void)printf(" (correct)");
 450
 451                 }
 452         }
 453 #endif
 454
 455         length -= hlen;
 456         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 457                 (void)printf(", seq %u", seq);
 458
 459                 if (length > 0) {
 460                         (void)printf(":%u", seq + length);
 461                 }
 462         }
 463
 464         if (flags & TH_ACK) {
 465                 (void)printf(", ack %u", ack);
 466         }
 467
 468         (void)printf(", win %d", win);
 469
 470         if (flags & TH_URG)
 471                 (void)printf(", urg %d", urp);
 472         /*
 473          * Handle any options.
 474          */
 475         if (hlen > sizeof(*tp)) {
 476                 register const u_char *cp;
 477                 register u_int i, opt, datalen;
 478                 register u_int len;
 479
 480                 hlen -= sizeof(*tp);
 481                 cp = (const u_char *)tp + sizeof(*tp);
 482                 printf(", options [");
 483                 while (hlen > 0) {
 484                         if (ch != '\0')
 485                                 putchar(ch);
 486                         TCHECK(*cp);
 487                         opt = *cp++;
 488                         if (ZEROLENOPT(opt))
 489                                 len = 1;
 490                         else {
 491                                 TCHECK(*cp);
 492                                 len = *cp++;    /* total including type, len */
 493                                 if (len < 2 || len > hlen)
 494                                         goto bad;
 495                                 --hlen;         /* account for length byte */
 496                         }
 497                         --hlen;                 /* account for type byte */
 498                         datalen = 0;
 499
 500 /* Bail if "l" bytes of data are not left or were not captured  */
 501 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 502
 503
 504                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 505
 506                         switch (opt) {
 507
 508                         case TCPOPT_MAXSEG:
 509                                 datalen = 2;
 510                                 LENCHECK(datalen);
 511                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 512                                 break;
 513
 514                         case TCPOPT_WSCALE:
 515                                 datalen = 1;
 516                                 LENCHECK(datalen);
 517                                 (void)printf(" %u", *cp);
 518                                 break;
 519
 520                         case TCPOPT_SACK:
 521                                 datalen = len - 2;
 522                                 if (datalen % 8 != 0) {
 523                                         (void)printf("malformed sack");
 524                                 } else {
 525                                         u_int32_t s, e;
 526
 527                                         (void)printf(" %d ", datalen / 8);
 528                                         for (i = 0; i < datalen; i += 8) {
 529                                                 LENCHECK(i + 4);
 530                                                 s = EXTRACT_32BITS(cp + i);
 531                                                 LENCHECK(i + 8);
 532                                                 e = EXTRACT_32BITS(cp + i + 4);
 533                                                 if (threv) {
 534                                                         s -= thseq;
 535                                                         e -= thseq;
 536                                                 } else {
 537                                                         s -= thack;
 538                                                         e -= thack;
 539                                                 }
 540                                                 (void)printf("{%u:%u}", s, e);
 541                                         }
 542                                 }
 543                                 break;
 544
 545                         case TCPOPT_CC:
 546                         case TCPOPT_CCNEW:
 547                         case TCPOPT_CCECHO:
 548                         case TCPOPT_ECHO:
 549                         case TCPOPT_ECHOREPLY:
 550
 551                                 /*
 552                                  * those options share their semantics.
 553                                  * fall through
 554                                  */
 555                                 datalen = 4;
 556                                 LENCHECK(datalen);
 557                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 558                                 break;
 559
 560                         case TCPOPT_TIMESTAMP:
 561                                 datalen = 8;
 562                                 LENCHECK(datalen);
 563                                 (void)printf(" val %u ecr %u",
 564                                              EXTRACT_32BITS(cp),
 565                                              EXTRACT_32BITS(cp + 4));
 566                                 break;
 567
 568                         case TCPOPT_SIGNATURE:
 569                                 datalen = TCP_SIGLEN;
 570                                 LENCHECK(datalen);
 571 #ifdef HAVE_LIBCRYPTO
 572                                 switch (tcp_verify_signature(ip, tp,
 573                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 574
 575                                 case SIGNATURE_VALID:
 576                                         (void)printf("valid");
 577                                         break;
 578
 579                                 case SIGNATURE_INVALID:
 580                                         (void)printf("invalid");
 581                                         break;
 582
 583                                 case CANT_CHECK_SIGNATURE:
 584                                         (void)printf("can't check - ");
 585                                         for (i = 0; i < TCP_SIGLEN; ++i)
 586                                                 (void)printf("%02x", cp[i]);
 587                                         break;
 588                                 }
 589 #else
 590                                 for (i = 0; i < TCP_SIGLEN; ++i)
 591                                         (void)printf("%02x", cp[i]);
 592 #endif
 593                                 break;
 594
 595                         case TCPOPT_AUTH:
 596                                 (void)printf("keyid %d", *cp++);
 597                                 datalen = len - 3;
 598                                 for (i = 0; i < datalen; ++i) {
 599                                         LENCHECK(i);
 600                                         (void)printf("%02x", cp[i]);
 601                                 }
 602                                 break;
 603
 604
 605                         case TCPOPT_EOL:
 606                         case TCPOPT_NOP:
 607                         case TCPOPT_SACKOK:
 608                                 /*
 609                                  * Nothing interesting.
 610                                  * fall through
 611                                  */
 612                                 break;
 613
 614                         case TCPOPT_UTO:
 615                                 datalen = 2;
 616                                 LENCHECK(datalen);
 617                                 uint utoval = EXTRACT_16BITS(cp);
 618                                 (void)printf("0x%x", utoval);
 619                                 if (utoval & 0x0001)
 620                                         utoval = (utoval >> 1) * 60;
 621                                 else
 622                                         utoval >>= 1;
 623                                 (void)printf(" %u", utoval);
 624                                 break;
 625
 626                         default:
 627                                 datalen = len - 2;
 628                                 for (i = 0; i < datalen; ++i) {
 629                                         LENCHECK(i);
 630                                         (void)printf("%02x", cp[i]);
 631                                 }
 632                                 break;
 633                         }
 634
 635                         /* Account for data printed */
 636                         cp += datalen;
 637                         hlen -= datalen;
 638
 639                         /* Check specification against observed length */
 640                         ++datalen;                      /* option octet */
 641                         if (!ZEROLENOPT(opt))
 642                                 ++datalen;              /* size octet */
 643                         if (datalen != len)
 644                                 (void)printf("[len %d]", len);
 645                         ch = ',';
 646                         if (opt == TCPOPT_EOL)
 647                                 break;
 648                 }
 649                 putchar(']');
 650         }
 651
 652         /*
 653          * Print length field before crawling down the stack.
 654          */
 655         printf(", length %u", length);
 656
 657         if (length <= 0)
 658                 return;
 659
 660         /*
 661          * Decode payload if necessary.
 662          */
 663         bp += TH_OFF(tp) * 4;
 664         if ((flags & TH_RST) && vflag) {
 665                 print_tcp_rst_data(bp, length);
 666                 return;
 667         }
 668
 669         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 670                 if (!qflag && vflag)
 671                         telnet_print(bp, length);
 672         } else if (sport == BGP_PORT || dport == BGP_PORT)
 673                 bgp_print(bp, length);
 674         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 675                 pptp_print(bp);
 676 #ifdef TCPDUMP_DO_SMB
 677         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 678                 nbt_tcp_print(bp, length);
 679         else if (sport == SMB_PORT || dport == SMB_PORT)
 680                 smb_tcp_print(bp, length);
 681 #endif
 682         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 683                 beep_print(bp, length);
 684         else if (length > 2 &&
 685                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 686                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 687                 /*
 688                  * TCP DNS query has 2byte length at the head.
 689                  * XXX packet could be unaligned, it can go strange
 690                  */
 691                 ns_print(bp + 2, length - 2, 0);
 692         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 693                 msdp_print(bp, length);
 694         }
 695         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 696                 ldp_print(bp, length);
 697         }
 698
 699         return;
 700  bad:
 701         fputs("[bad opt]", stdout);
 702         if (ch != '\0')
 703                 putchar('>');
 704         return;
 705  trunc:
 706         fputs("[|tcp]", stdout);
 707         if (ch != '\0')
 708                 putchar('>');
 709 }
 710
 711 /*
 712  * RFC1122 says the following on data in RST segments:
 713  *
 714  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 715  *
 716  *            A TCP SHOULD allow a received RST segment to include data.
 717  *
 718  *            DISCUSSION
 719  *                 It has been suggested that a RST segment could contain
 720  *                 ASCII text that encoded and explained the cause of the
 721  *                 RST.  No standard has yet been established for such
 722  *                 data.
 723  *
 724  */
 725
 726 static void
 727 print_tcp_rst_data(register const u_char *sp, u_int length)
 728 {
 729         int c;
 730
 731         if (TTEST2(*sp, length))
 732                 printf(" [RST");
 733         else
 734                 printf(" [!RST");
 735         if (length > MAX_RST_DATA_LEN) {
 736                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 737                 putchar('+');                   /* indicate we truncate */
 738         }
 739         putchar(' ');
 740         while (length-- && sp <= snapend) {
 741                 c = *sp++;
 742                 safeputchar(c);
 743         }
 744         putchar(']');
 745 }
 746
 747 #ifdef HAVE_LIBCRYPTO
 748 static int
 749 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 750                      const u_char *data, int length, const u_char *rcvsig)
 751 {
 752         struct tcphdr tp1;
 753         u_char sig[TCP_SIGLEN];
 754         char zero_proto = 0;
 755         MD5_CTX ctx;
 756         u_int16_t savecsum, tlen;
 757 #ifdef INET6
 758         struct ip6_hdr *ip6;
 759         u_int32_t len32;
 760         u_int8_t nxt;
 761 #endif
 762
 763         if (data + length > snapend) {
 764                 printf("snaplen too short, ");
 765                 return (CANT_CHECK_SIGNATURE);
 766         }
 767
 768         tp1 = *tp;
 769
 770         if (sigsecret == NULL) {
 771                 printf("shared secret not supplied with -M, ");
 772                 return (CANT_CHECK_SIGNATURE);
 773         }
 774
 775         MD5_Init(&ctx);
 776         /*
 777          * Step 1: Update MD5 hash with IP pseudo-header.
 778          */
 779         if (IP_V(ip) == 4) {
 780                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 781                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 782                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 783                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 784                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 785                 tlen = htons(tlen);
 786                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 787 #ifdef INET6
 788         } else if (IP_V(ip) == 6) {
 789                 ip6 = (struct ip6_hdr *)ip;
 790                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 791                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 792                 len32 = htonl(ntohs(ip6->ip6_plen));
 793                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 794                 nxt = 0;
 795                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 796                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 797                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 798                 nxt = IPPROTO_TCP;
 799                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 800 #endif
 801         } else {
 802 #ifdef INET6
 803                 printf("IP version not 4 or 6, ");
 804 #else
 805                 printf("IP version not 4, ");
 806 #endif
 807                 return (CANT_CHECK_SIGNATURE);
 808         }
 809
 810         /*
 811          * Step 2: Update MD5 hash with TCP header, excluding options.
 812          * The TCP checksum must be set to zero.
 813          */
 814         savecsum = tp1.th_sum;
 815         tp1.th_sum = 0;
 816         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 817         tp1.th_sum = savecsum;
 818         /*
 819          * Step 3: Update MD5 hash with TCP segment data, if present.
 820          */
 821         if (length > 0)
 822                 MD5_Update(&ctx, data, length);
 823         /*
 824          * Step 4: Update MD5 hash with shared secret.
 825          */
 826         MD5_Update(&ctx, sigsecret, strlen(sigsecret));
 827         MD5_Final(sig, &ctx);
 828
 829         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 830                 return (SIGNATURE_VALID);
 831         else
 832                 return (SIGNATURE_INVALID);
 833 }
 834 #endif /* HAVE_LIBCRYPTO */
 835
 836 /*
 837  * Local Variables:
 838  * c-style: whitesmith
 839  * c-basic-offset: 8
 840  * End:
 841  */