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 void
 160 tcp_print(register const u_char *bp, register u_int length,
 161           register const u_char *bp2, int fragmented)
 162 {
 163         register const struct tcphdr *tp;
 164         register const struct ip *ip;
 165         register u_char flags;
 166         register u_int hlen;
 167         register char ch;
 168         u_int16_t sport, dport, win, urp;
 169         u_int32_t seq, ack, thseq, thack;
 170         u_int utoval;
 171         int threv;
 172 #ifdef INET6
 173         register const struct ip6_hdr *ip6;
 174 #endif
 175
 176         tp = (struct tcphdr *)bp;
 177         ip = (struct ip *)bp2;
 178 #ifdef INET6
 179         if (IP_V(ip) == 6)
 180                 ip6 = (struct ip6_hdr *)bp2;
 181         else
 182                 ip6 = NULL;
 183 #endif /*INET6*/
 184         ch = '\0';
 185         if (!TTEST(tp->th_dport)) {
 186                 (void)printf("%s > %s: [|tcp]",
 187                              ipaddr_string(&ip->ip_src),
 188                              ipaddr_string(&ip->ip_dst));
 189                 return;
 190         }
 191
 192         sport = EXTRACT_16BITS(&tp->th_sport);
 193         dport = EXTRACT_16BITS(&tp->th_dport);
 194
 195         hlen = TH_OFF(tp) * 4;
 196
 197         /*
 198          * If data present, header length valid, and NFS port used,
 199          * assume NFS.
 200          * Pass offset of data plus 4 bytes for RPC TCP msg length
 201          * to NFS print routines.
 202          */
 203         if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
 204             (length - hlen) >= 4) {
 205                 u_char *fraglenp;
 206                 u_int32_t fraglen;
 207                 register struct sunrpc_msg *rp;
 208                 enum sunrpc_msg_type direction;
 209
 210                 fraglenp = (u_char *)tp + hlen;
 211                 if (TTEST2(*fraglenp, 4)) {
 212                         fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
 213                         if (fraglen > (length - hlen) - 4)
 214                                 fraglen = (length - hlen) - 4;
 215                         rp = (struct sunrpc_msg *)(fraglenp + 4);
 216                         if (TTEST(rp->rm_direction)) {
 217                                 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
 218                                 if (dport == NFS_PORT &&
 219                                     direction == SUNRPC_CALL) {
 220                                         nfsreq_print((u_char *)rp, fraglen,
 221                                             (u_char *)ip);
 222                                         return;
 223                                 }
 224                                 if (sport == NFS_PORT &&
 225                                     direction == SUNRPC_REPLY) {
 226                                         nfsreply_print((u_char *)rp, fraglen,
 227                                             (u_char *)ip);
 228                                         return;
 229                                 }
 230                         }
 231                 }
 232         }
 233 #ifdef INET6
 234         if (ip6) {
 235                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 236                         (void)printf("%s.%s > %s.%s: ",
 237                                      ip6addr_string(&ip6->ip6_src),
 238                                      tcpport_string(sport),
 239                                      ip6addr_string(&ip6->ip6_dst),
 240                                      tcpport_string(dport));
 241                 } else {
 242                         (void)printf("%s > %s: ",
 243                                      tcpport_string(sport), tcpport_string(dport));
 244                 }
 245         } else
 246 #endif /*INET6*/
 247         {
 248                 if (ip->ip_p == IPPROTO_TCP) {
 249                         (void)printf("%s.%s > %s.%s: ",
 250                                      ipaddr_string(&ip->ip_src),
 251                                      tcpport_string(sport),
 252                                      ipaddr_string(&ip->ip_dst),
 253                                      tcpport_string(dport));
 254                 } else {
 255                         (void)printf("%s > %s: ",
 256                                      tcpport_string(sport), tcpport_string(dport));
 257                 }
 258         }
 259
 260         if (hlen < sizeof(*tp)) {
 261                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 262                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 263                 return;
 264         }
 265
 266         TCHECK(*tp);
 267
 268         seq = EXTRACT_32BITS(&tp->th_seq);
 269         ack = EXTRACT_32BITS(&tp->th_ack);
 270         win = EXTRACT_16BITS(&tp->th_win);
 271         urp = EXTRACT_16BITS(&tp->th_urp);
 272
 273         if (qflag) {
 274                 (void)printf("tcp %d", length - hlen);
 275                 if (hlen > length) {
 276                         (void)printf(" [bad hdr length %u - too long, > %u]",
 277                                      hlen, length);
 278                 }
 279                 return;
 280         }
 281
 282         flags = tp->th_flags;
 283         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 284
 285         if (!Sflag && (flags & TH_ACK)) {
 286                 register struct tcp_seq_hash *th;
 287                 const void *src, *dst;
 288                 register int rev;
 289                 struct tha tha;
 290                 /*
 291                  * Find (or record) the initial sequence numbers for
 292                  * this conversation.  (we pick an arbitrary
 293                  * collating order so there's only one entry for
 294                  * both directions).
 295                  */
 296 #ifdef INET6
 297                 rev = 0;
 298                 if (ip6) {
 299                         src = &ip6->ip6_src;
 300                         dst = &ip6->ip6_dst;
 301                         if (sport > dport)
 302                                 rev = 1;
 303                         else if (sport == dport) {
 304                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 305                                         rev = 1;
 306                         }
 307                         if (rev) {
 308                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 309                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 310                                 tha.port = dport << 16 | sport;
 311                         } else {
 312                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 313                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 314                                 tha.port = sport << 16 | dport;
 315                         }
 316                 } else {
 317                         /*
 318                          * Zero out the tha structure; the src and dst
 319                          * fields are big enough to hold an IPv6
 320                          * address, but we only have IPv4 addresses
 321                          * and thus must clear out the remaining 124
 322                          * bytes.
 323                          *
 324                          * XXX - should we just clear those bytes after
 325                          * copying the IPv4 addresses, rather than
 326                          * zeroing out the entire structure and then
 327                          * overwriting some of the zeroes?
 328                          */
 329                         memset(&tha, 0, sizeof(tha));
 330                         src = &ip->ip_src;
 331                         dst = &ip->ip_dst;
 332                         if (sport > dport)
 333                                 rev = 1;
 334                         else if (sport == dport) {
 335                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 336                                         rev = 1;
 337                         }
 338                         if (rev) {
 339                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 340                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 341                                 tha.port = dport << 16 | sport;
 342                         } else {
 343                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 344                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 345                                 tha.port = sport << 16 | dport;
 346                         }
 347                 }
 348 #else
 349                 rev = 0;
 350                 src = &ip->ip_src;
 351                 dst = &ip->ip_dst;
 352                 if (sport > dport)
 353                         rev = 1;
 354                 else if (sport == dport) {
 355                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 356                                 rev = 1;
 357                 }
 358                 if (rev) {
 359                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 360                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 361                         tha.port = dport << 16 | sport;
 362                 } else {
 363                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 364                         memcpy(&tha.src, src, sizeof ip->ip_src);
 365                         tha.port = sport << 16 | dport;
 366                 }
 367 #endif
 368
 369                 threv = rev;
 370                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 371                      th->nxt; th = th->nxt)
 372                         if (memcmp((char *)&tha, (char *)&th->addr,
 373                                    sizeof(th->addr)) == 0)
 374                                 break;
 375
 376                 if (!th->nxt || (flags & TH_SYN)) {
 377                         /* didn't find it or new conversation */
 378                         if (th->nxt == NULL) {
 379                                 th->nxt = (struct tcp_seq_hash *)
 380                                         calloc(1, sizeof(*th));
 381                                 if (th->nxt == NULL)
 382                                         error("tcp_print: calloc");
 383                         }
 384                         th->addr = tha;
 385                         if (rev)
 386                                 th->ack = seq, th->seq = ack - 1;
 387                         else
 388                                 th->seq = seq, th->ack = ack - 1;
 389                 } else {
 390                         if (rev)
 391                                 seq -= th->ack, ack -= th->seq;
 392                         else
 393                                 seq -= th->seq, ack -= th->ack;
 394                 }
 395
 396                 thseq = th->seq;
 397                 thack = th->ack;
 398         } else {
 399                 /*fool gcc*/
 400                 thseq = thack = threv = 0;
 401         }
 402         if (hlen > length) {
 403                 (void)printf(" [bad hdr length %u - too long, > %u]",
 404                              hlen, length);
 405                 return;
 406         }
 407
 408         if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 409                 u_int16_t sum, tcp_sum;
 410                 if (TTEST2(tp->th_sport, length)) {
 411                         sum = tcp_cksum(ip, tp, length);
 412
 413                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 414                         if (sum != 0) {
 415                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 416                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 417                         } else
 418                                 (void)printf(" (correct)");
 419                 }
 420         }
 421 #ifdef INET6
 422         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 423                 u_int16_t sum,tcp_sum;
 424                 if (TTEST2(tp->th_sport, length)) {
 425                         sum = nextproto6_cksum(ip6, (u_short *)tp, length, IPPROTO_TCP);
 426                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 427                         if (sum != 0) {
 428                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 429                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 430                         } else
 431                                 (void)printf(" (correct)");
 432
 433                 }
 434         }
 435 #endif
 436
 437         length -= hlen;
 438         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 439                 (void)printf(", seq %u", seq);
 440
 441                 if (length > 0) {
 442                         (void)printf(":%u", seq + length);
 443                 }
 444         }
 445
 446         if (flags & TH_ACK) {
 447                 (void)printf(", ack %u", ack);
 448         }
 449
 450         (void)printf(", win %d", win);
 451
 452         if (flags & TH_URG)
 453                 (void)printf(", urg %d", urp);
 454         /*
 455          * Handle any options.
 456          */
 457         if (hlen > sizeof(*tp)) {
 458                 register const u_char *cp;
 459                 register u_int i, opt, datalen;
 460                 register u_int len;
 461
 462                 hlen -= sizeof(*tp);
 463                 cp = (const u_char *)tp + sizeof(*tp);
 464                 printf(", options [");
 465                 while (hlen > 0) {
 466                         if (ch != '\0')
 467                                 putchar(ch);
 468                         TCHECK(*cp);
 469                         opt = *cp++;
 470                         if (ZEROLENOPT(opt))
 471                                 len = 1;
 472                         else {
 473                                 TCHECK(*cp);
 474                                 len = *cp++;    /* total including type, len */
 475                                 if (len < 2 || len > hlen)
 476                                         goto bad;
 477                                 --hlen;         /* account for length byte */
 478                         }
 479                         --hlen;                 /* account for type byte */
 480                         datalen = 0;
 481
 482 /* Bail if "l" bytes of data are not left or were not captured  */
 483 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 484
 485
 486                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 487
 488                         switch (opt) {
 489
 490                         case TCPOPT_MAXSEG:
 491                                 datalen = 2;
 492                                 LENCHECK(datalen);
 493                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 494                                 break;
 495
 496                         case TCPOPT_WSCALE:
 497                                 datalen = 1;
 498                                 LENCHECK(datalen);
 499                                 (void)printf(" %u", *cp);
 500                                 break;
 501
 502                         case TCPOPT_SACK:
 503                                 datalen = len - 2;
 504                                 if (datalen % 8 != 0) {
 505                                         (void)printf("malformed sack");
 506                                 } else {
 507                                         u_int32_t s, e;
 508
 509                                         (void)printf(" %d ", datalen / 8);
 510                                         for (i = 0; i < datalen; i += 8) {
 511                                                 LENCHECK(i + 4);
 512                                                 s = EXTRACT_32BITS(cp + i);
 513                                                 LENCHECK(i + 8);
 514                                                 e = EXTRACT_32BITS(cp + i + 4);
 515                                                 if (threv) {
 516                                                         s -= thseq;
 517                                                         e -= thseq;
 518                                                 } else {
 519                                                         s -= thack;
 520                                                         e -= thack;
 521                                                 }
 522                                                 (void)printf("{%u:%u}", s, e);
 523                                         }
 524                                 }
 525                                 break;
 526
 527                         case TCPOPT_CC:
 528                         case TCPOPT_CCNEW:
 529                         case TCPOPT_CCECHO:
 530                         case TCPOPT_ECHO:
 531                         case TCPOPT_ECHOREPLY:
 532
 533                                 /*
 534                                  * those options share their semantics.
 535                                  * fall through
 536                                  */
 537                                 datalen = 4;
 538                                 LENCHECK(datalen);
 539                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 540                                 break;
 541
 542                         case TCPOPT_TIMESTAMP:
 543                                 datalen = 8;
 544                                 LENCHECK(datalen);
 545                                 (void)printf(" val %u ecr %u",
 546                                              EXTRACT_32BITS(cp),
 547                                              EXTRACT_32BITS(cp + 4));
 548                                 break;
 549
 550                         case TCPOPT_SIGNATURE:
 551                                 datalen = TCP_SIGLEN;
 552                                 LENCHECK(datalen);
 553 #ifdef HAVE_LIBCRYPTO
 554                                 switch (tcp_verify_signature(ip, tp,
 555                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 556
 557                                 case SIGNATURE_VALID:
 558                                         (void)printf("valid");
 559                                         break;
 560
 561                                 case SIGNATURE_INVALID:
 562                                         (void)printf("invalid");
 563                                         break;
 564
 565                                 case CANT_CHECK_SIGNATURE:
 566                                         (void)printf("can't check - ");
 567                                         for (i = 0; i < TCP_SIGLEN; ++i)
 568                                                 (void)printf("%02x", cp[i]);
 569                                         break;
 570                                 }
 571 #else
 572                                 for (i = 0; i < TCP_SIGLEN; ++i)
 573                                         (void)printf("%02x", cp[i]);
 574 #endif
 575                                 break;
 576
 577                         case TCPOPT_AUTH:
 578                                 (void)printf("keyid %d", *cp++);
 579                                 datalen = len - 3;
 580                                 for (i = 0; i < datalen; ++i) {
 581                                         LENCHECK(i);
 582                                         (void)printf("%02x", cp[i]);
 583                                 }
 584                                 break;
 585
 586
 587                         case TCPOPT_EOL:
 588                         case TCPOPT_NOP:
 589                         case TCPOPT_SACKOK:
 590                                 /*
 591                                  * Nothing interesting.
 592                                  * fall through
 593                                  */
 594                                 break;
 595
 596                         case TCPOPT_UTO:
 597                                 datalen = 2;
 598                                 LENCHECK(datalen);
 599                                 utoval = EXTRACT_16BITS(cp);
 600                                 (void)printf("0x%x", utoval);
 601                                 if (utoval & 0x0001)
 602                                         utoval = (utoval >> 1) * 60;
 603                                 else
 604                                         utoval >>= 1;
 605                                 (void)printf(" %u", utoval);
 606                                 break;
 607
 608                         default:
 609                                 datalen = len - 2;
 610                                 for (i = 0; i < datalen; ++i) {
 611                                         LENCHECK(i);
 612                                         (void)printf("%02x", cp[i]);
 613                                 }
 614                                 break;
 615                         }
 616
 617                         /* Account for data printed */
 618                         cp += datalen;
 619                         hlen -= datalen;
 620
 621                         /* Check specification against observed length */
 622                         ++datalen;                      /* option octet */
 623                         if (!ZEROLENOPT(opt))
 624                                 ++datalen;              /* size octet */
 625                         if (datalen != len)
 626                                 (void)printf("[len %d]", len);
 627                         ch = ',';
 628                         if (opt == TCPOPT_EOL)
 629                                 break;
 630                 }
 631                 putchar(']');
 632         }
 633
 634         /*
 635          * Print length field before crawling down the stack.
 636          */
 637         printf(", length %u", length);
 638
 639         if (length <= 0)
 640                 return;
 641
 642         /*
 643          * Decode payload if necessary.
 644          */
 645         bp += TH_OFF(tp) * 4;
 646         if ((flags & TH_RST) && vflag) {
 647                 print_tcp_rst_data(bp, length);
 648                 return;
 649         }
 650
 651         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 652                 if (!qflag && vflag)
 653                         telnet_print(bp, length);
 654         } else if (sport == BGP_PORT || dport == BGP_PORT)
 655                 bgp_print(bp, length);
 656         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 657                 pptp_print(bp);
 658 #ifdef TCPDUMP_DO_SMB
 659         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 660                 nbt_tcp_print(bp, length);
 661         else if (sport == SMB_PORT || dport == SMB_PORT)
 662                 smb_tcp_print(bp, length);
 663 #endif
 664         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 665                 beep_print(bp, length);
 666         else if (length > 2 &&
 667                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 668                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 669                 /*
 670                  * TCP DNS query has 2byte length at the head.
 671                  * XXX packet could be unaligned, it can go strange
 672                  */
 673                 ns_print(bp + 2, length - 2, 0);
 674         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 675                 msdp_print(bp, length);
 676         }
 677         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 678                 ldp_print(bp, length);
 679         }
 680
 681         return;
 682  bad:
 683         fputs("[bad opt]", stdout);
 684         if (ch != '\0')
 685                 putchar('>');
 686         return;
 687  trunc:
 688         fputs("[|tcp]", stdout);
 689         if (ch != '\0')
 690                 putchar('>');
 691 }
 692
 693 /*
 694  * RFC1122 says the following on data in RST segments:
 695  *
 696  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 697  *
 698  *            A TCP SHOULD allow a received RST segment to include data.
 699  *
 700  *            DISCUSSION
 701  *                 It has been suggested that a RST segment could contain
 702  *                 ASCII text that encoded and explained the cause of the
 703  *                 RST.  No standard has yet been established for such
 704  *                 data.
 705  *
 706  */
 707
 708 static void
 709 print_tcp_rst_data(register const u_char *sp, u_int length)
 710 {
 711         int c;
 712
 713         if (TTEST2(*sp, length))
 714                 printf(" [RST");
 715         else
 716                 printf(" [!RST");
 717         if (length > MAX_RST_DATA_LEN) {
 718                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 719                 putchar('+');                   /* indicate we truncate */
 720         }
 721         putchar(' ');
 722         while (length-- && sp <= snapend) {
 723                 c = *sp++;
 724                 safeputchar(c);
 725         }
 726         putchar(']');
 727 }
 728
 729 #ifdef HAVE_LIBCRYPTO
 730 static int
 731 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 732                      const u_char *data, int length, const u_char *rcvsig)
 733 {
 734         struct tcphdr tp1;
 735         u_char sig[TCP_SIGLEN];
 736         char zero_proto = 0;
 737         MD5_CTX ctx;
 738         u_int16_t savecsum, tlen;
 739 #ifdef INET6
 740         struct ip6_hdr *ip6;
 741         u_int32_t len32;
 742         u_int8_t nxt;
 743 #endif
 744
 745         if (data + length > snapend) {
 746                 printf("snaplen too short, ");
 747                 return (CANT_CHECK_SIGNATURE);
 748         }
 749
 750         tp1 = *tp;
 751
 752         if (sigsecret == NULL) {
 753                 printf("shared secret not supplied with -M, ");
 754                 return (CANT_CHECK_SIGNATURE);
 755         }
 756
 757         MD5_Init(&ctx);
 758         /*
 759          * Step 1: Update MD5 hash with IP pseudo-header.
 760          */
 761         if (IP_V(ip) == 4) {
 762                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 763                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 764                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 765                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 766                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 767                 tlen = htons(tlen);
 768                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 769 #ifdef INET6
 770         } else if (IP_V(ip) == 6) {
 771                 ip6 = (struct ip6_hdr *)ip;
 772                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 773                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 774                 len32 = htonl(EXTRACT_16BITS(&ip6->ip6_plen));
 775                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 776                 nxt = 0;
 777                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 778                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 779                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 780                 nxt = IPPROTO_TCP;
 781                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 782 #endif
 783         } else {
 784 #ifdef INET6
 785                 printf("IP version not 4 or 6, ");
 786 #else
 787                 printf("IP version not 4, ");
 788 #endif
 789                 return (CANT_CHECK_SIGNATURE);
 790         }
 791
 792         /*
 793          * Step 2: Update MD5 hash with TCP header, excluding options.
 794          * The TCP checksum must be set to zero.
 795          */
 796         savecsum = tp1.th_sum;
 797         tp1.th_sum = 0;
 798         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 799         tp1.th_sum = savecsum;
 800         /*
 801          * Step 3: Update MD5 hash with TCP segment data, if present.
 802          */
 803         if (length > 0)
 804                 MD5_Update(&ctx, data, length);
 805         /*
 806          * Step 4: Update MD5 hash with shared secret.
 807          */
 808         MD5_Update(&ctx, sigsecret, strlen(sigsecret));
 809         MD5_Final(sig, &ctx);
 810
 811         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 812                 return (SIGNATURE_VALID);
 813         else
 814                 return (SIGNATURE_INVALID);
 815 }
 816 #endif /* HAVE_LIBCRYPTO */
 817
 818 /*
 819  * Local Variables:
 820  * c-style: whitesmith
 821  * c-basic-offset: 8
 822  * End:
 823  */