The Tcpdump Group git mirrors - tcpdump/blob - print-tcp.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  * Copyright (c) 1999-2004 The tcpdump.org project
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that: (1) source code distributions
   9  * retain the above copyright notice and this paragraph in its entirety, (2)
  10  * distributions including binary code include the above copyright notice and
  11  * this paragraph in its entirety in the documentation or other materials
  12  * provided with the distribution, and (3) all advertising materials mentioning
  13  * features or use of this software display the following acknowledgement:
  14  * ``This product includes software developed by the University of California,
  15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  16  * the University nor the names of its contributors may be used to endorse
  17  * or promote products derived from this software without specific prior
  18  * written permission.
  19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  22  */
  23
  24 #ifndef lint
  25 static const char rcsid[] _U_ =
  26     "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.126 2006-11-02 08:56:16 hannes Exp $ (LBL)";
  27 #endif
  28
  29 #ifdef HAVE_CONFIG_H
  30 #include "config.h"
  31 #endif
  32
  33 #include <tcpdump-stdinc.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #include "interface.h"
  40 #include "addrtoname.h"
  41 #include "extract.h"
  42
  43 #include "tcp.h"
  44
  45 #include "ip.h"
  46 #ifdef INET6
  47 #include "ip6.h"
  48 #endif
  49 #include "ipproto.h"
  50 #include "rpc_auth.h"
  51 #include "rpc_msg.h"
  52
  53 #include "nameser.h"
  54
  55 #ifdef HAVE_LIBCRYPTO
  56 #include <openssl/md5.h>
  57
  58 #define SIGNATURE_VALID         0
  59 #define SIGNATURE_INVALID       1
  60 #define CANT_CHECK_SIGNATURE    2
  61
  62 static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
  63     const u_char *data, int length, const u_char *rcvsig);
  64 #endif
  65
  66 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  67
  68 #define MAX_RST_DATA_LEN        30
  69
  70
  71 struct tha {
  72 #ifndef INET6
  73         struct in_addr src;
  74         struct in_addr dst;
  75 #else
  76         struct in6_addr src;
  77         struct in6_addr dst;
  78 #endif /*INET6*/
  79         u_int port;
  80 };
  81
  82 struct tcp_seq_hash {
  83         struct tcp_seq_hash *nxt;
  84         struct tha addr;
  85         tcp_seq seq;
  86         tcp_seq ack;
  87 };
  88
  89 #define TSEQ_HASHSIZE 919
  90
  91 /* These tcp optinos do not have the size octet */
  92 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
  93
  94 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
  95
  96
  97 #ifndef TELNET_PORT
  98 #define TELNET_PORT     23
  99 #endif
 100 #ifndef BGP_PORT
 101 #define BGP_PORT        179
 102 #endif
 103 #define NETBIOS_SSN_PORT 139
 104 #ifndef PPTP_PORT
 105 #define PPTP_PORT       1723
 106 #endif
 107 #define BEEP_PORT        10288
 108 #ifndef NFS_PORT
 109 #define NFS_PORT        2049
 110 #endif
 111 #define MSDP_PORT       639
 112 #define LDP_PORT        646
 113
 114 static int tcp_cksum(register const struct ip *ip,
 115                      register const struct tcphdr *tp,
 116                      register u_int len)
 117 {
 118         union phu {
 119                 struct phdr {
 120                         u_int32_t src;
 121                         u_int32_t dst;
 122                         u_char mbz;
 123                         u_char proto;
 124                         u_int16_t len;
 125                 } ph;
 126                 u_int16_t pa[6];
 127         } phu;
 128         const u_int16_t *sp;
 129
 130         /* pseudo-header.. */
 131         phu.ph.len = htons((u_int16_t)len);
 132         phu.ph.mbz = 0;
 133         phu.ph.proto = IPPROTO_TCP;
 134         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 135         if (IP_HL(ip) == 5)
 136                 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 137         else
 138                 phu.ph.dst = ip_finddst(ip);
 139
 140         sp = &phu.pa[0];
 141         return in_cksum((u_short *)tp, len,
 142                         sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
 143 }
 144
 145 #ifdef INET6
 146 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 147         u_int len)
 148 {
 149         size_t i;
 150         u_int32_t sum = 0;
 151         union {
 152                 struct {
 153                         struct in6_addr ph_src;
 154                         struct in6_addr ph_dst;
 155                         u_int32_t       ph_len;
 156                         u_int8_t        ph_zero[3];
 157                         u_int8_t        ph_nxt;
 158                 } ph;
 159                 u_int16_t pa[20];
 160         } phu;
 161
 162         /* pseudo-header */
 163         memset(&phu, 0, sizeof(phu));
 164         phu.ph.ph_src = ip6->ip6_src;
 165         phu.ph.ph_dst = ip6->ip6_dst;
 166         phu.ph.ph_len = htonl(len);
 167         phu.ph.ph_nxt = IPPROTO_TCP;
 168
 169         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 170                 sum += phu.pa[i];
 171
 172         return in_cksum((u_short *)tp, len, sum);
 173 }
 174 #endif
 175
 176 void
 177 tcp_print(register const u_char *bp, register u_int length,
 178           register const u_char *bp2, int fragmented)
 179 {
 180         register const struct tcphdr *tp;
 181         register const struct ip *ip;
 182         register u_char flags;
 183         register u_int hlen;
 184         register char ch;
 185         u_int16_t sport, dport, win, urp;
 186         u_int32_t seq, ack, thseq, thack;
 187         int threv;
 188 #ifdef INET6
 189         register const struct ip6_hdr *ip6;
 190 #endif
 191
 192         tp = (struct tcphdr *)bp;
 193         ip = (struct ip *)bp2;
 194 #ifdef INET6
 195         if (IP_V(ip) == 6)
 196                 ip6 = (struct ip6_hdr *)bp2;
 197         else
 198                 ip6 = NULL;
 199 #endif /*INET6*/
 200         ch = '\0';
 201         if (!TTEST(tp->th_dport)) {
 202                 (void)printf("%s > %s: [|tcp]",
 203                         ipaddr_string(&ip->ip_src),
 204                         ipaddr_string(&ip->ip_dst));
 205                 return;
 206         }
 207
 208         sport = EXTRACT_16BITS(&tp->th_sport);
 209         dport = EXTRACT_16BITS(&tp->th_dport);
 210
 211         hlen = TH_OFF(tp) * 4;
 212
 213         /*
 214          * If data present, header length valid, and NFS port used,
 215          * assume NFS.
 216          * Pass offset of data plus 4 bytes for RPC TCP msg length
 217          * to NFS print routines.
 218          */
 219         if (!qflag && hlen >= sizeof(*tp) && hlen <= length) {
 220                 if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg) <= snapend &&
 221                     dport == NFS_PORT) {
 222                         nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
 223                                      (u_char *)ip);
 224                         return;
 225                 } else if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg)
 226                            <= snapend &&
 227                            sport == NFS_PORT) {
 228                         nfsreply_print((u_char *)tp + hlen + 4, length - hlen,
 229                                        (u_char *)ip);
 230                         return;
 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         if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
 282                                       TH_ECNECHO|TH_CWR)) {
 283                 if (flags & TH_SYN)
 284                         putchar('S');
 285                 if (flags & TH_FIN)
 286                         putchar('F');
 287                 if (flags & TH_RST)
 288                         putchar('R');
 289                 if (flags & TH_PUSH)
 290                         putchar('P');
 291                 if (flags & TH_CWR)
 292                         putchar('W');   /* congestion _W_indow reduced (ECN) */
 293                 if (flags & TH_ECNECHO)
 294                         putchar('E');   /* ecn _E_cho sent (ECN) */
 295         } else
 296                 putchar('.');
 297
 298         if (!Sflag && (flags & TH_ACK)) {
 299                 register struct tcp_seq_hash *th;
 300                 const void *src, *dst;
 301                 register int rev;
 302                 struct tha tha;
 303                 /*
 304                  * Find (or record) the initial sequence numbers for
 305                  * this conversation.  (we pick an arbitrary
 306                  * collating order so there's only one entry for
 307                  * both directions).
 308                  */
 309 #ifdef INET6
 310                 memset(&tha, 0, sizeof(tha));
 311                 rev = 0;
 312                 if (ip6) {
 313                         src = &ip6->ip6_src;
 314                         dst = &ip6->ip6_dst;
 315                         if (sport > dport)
 316                                 rev = 1;
 317                         else if (sport == dport) {
 318                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 319                                         rev = 1;
 320                         }
 321                         if (rev) {
 322                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 323                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 324                                 tha.port = dport << 16 | sport;
 325                         } else {
 326                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 327                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 328                                 tha.port = sport << 16 | dport;
 329                         }
 330                 } else {
 331                         src = &ip->ip_src;
 332                         dst = &ip->ip_dst;
 333                         if (sport > dport)
 334                                 rev = 1;
 335                         else if (sport == dport) {
 336                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 337                                         rev = 1;
 338                         }
 339                         if (rev) {
 340                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 341                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 342                                 tha.port = dport << 16 | sport;
 343                         } else {
 344                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 345                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 346                                 tha.port = sport << 16 | dport;
 347                         }
 348                 }
 349 #else
 350                 rev = 0;
 351                 src = &ip->ip_src;
 352                 dst = &ip->ip_dst;
 353                 if (sport > dport)
 354                         rev = 1;
 355                 else if (sport == dport) {
 356                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 357                                 rev = 1;
 358                 }
 359                 if (rev) {
 360                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 361                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 362                         tha.port = dport << 16 | sport;
 363                 } else {
 364                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 365                         memcpy(&tha.src, src, sizeof ip->ip_src);
 366                         tha.port = sport << 16 | dport;
 367                 }
 368 #endif
 369
 370                 threv = rev;
 371                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 372                      th->nxt; th = th->nxt)
 373                         if (memcmp((char *)&tha, (char *)&th->addr,
 374                                   sizeof(th->addr)) == 0)
 375                                 break;
 376
 377                 if (!th->nxt || (flags & TH_SYN)) {
 378                         /* didn't find it or new conversation */
 379                         if (th->nxt == NULL) {
 380                                 th->nxt = (struct tcp_seq_hash *)
 381                                         calloc(1, sizeof(*th));
 382                                 if (th->nxt == NULL)
 383                                         error("tcp_print: calloc");
 384                         }
 385                         th->addr = tha;
 386                         if (rev)
 387                                 th->ack = seq, th->seq = ack - 1;
 388                         else
 389                                 th->seq = seq, th->ack = ack - 1;
 390                 } else {
 391                         if (rev)
 392                                 seq -= th->ack, ack -= th->seq;
 393                         else
 394                                 seq -= th->seq, ack -= th->ack;
 395                 }
 396
 397                 thseq = th->seq;
 398                 thack = th->ack;
 399         } else {
 400                 /*fool gcc*/
 401                 thseq = thack = threv = 0;
 402         }
 403         if (hlen > length) {
 404                 (void)printf(" [bad hdr length %u - too long, > %u]",
 405                     hlen, length);
 406                 return;
 407         }
 408
 409         if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 410                 u_int16_t sum, tcp_sum;
 411                 if (TTEST2(tp->th_sport, length)) {
 412                         sum = tcp_cksum(ip, tp, length);
 413
 414                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 415                         if (sum != 0) {
 416                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 417                                 (void)printf(" (incorrect -> 0x%04x),",in_cksum_shouldbe(tcp_sum, sum));
 418                         } else
 419                                 (void)printf(" (correct),");
 420                 }
 421         }
 422 #ifdef INET6
 423         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 424                 u_int16_t sum,tcp_sum;
 425                 if (TTEST2(tp->th_sport, length)) {
 426                         sum = tcp6_cksum(ip6, tp, length);
 427                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 428                         if (sum != 0) {
 429                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 430                                 (void)printf(" (incorrect (-> 0x%04x),",in_cksum_shouldbe(tcp_sum, sum));
 431                         } else
 432                                 (void)printf(" (correct),");
 433
 434                 }
 435         }
 436 #endif
 437
 438         length -= hlen;
 439         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
 440                 (void)printf(" %u:%u(%u)", seq, seq + length, length);
 441         if (flags & TH_ACK)
 442                 (void)printf(" ack %u", ack);
 443
 444         (void)printf(" win %d", win);
 445
 446         if (flags & TH_URG)
 447                 (void)printf(" urg %d", urp);
 448         /*
 449          * Handle any options.
 450          */
 451         if (hlen > sizeof(*tp)) {
 452                 register const u_char *cp;
 453                 register u_int i, opt, datalen;
 454                 register u_int len;
 455
 456                 hlen -= sizeof(*tp);
 457                 cp = (const u_char *)tp + sizeof(*tp);
 458                 putchar(' ');
 459                 ch = '<';
 460                 while (hlen > 0) {
 461                         putchar(ch);
 462                         TCHECK(*cp);
 463                         opt = *cp++;
 464                         if (ZEROLENOPT(opt))
 465                                 len = 1;
 466                         else {
 467                                 TCHECK(*cp);
 468                                 len = *cp++;    /* total including type, len */
 469                                 if (len < 2 || len > hlen)
 470                                         goto bad;
 471                                 --hlen;         /* account for length byte */
 472                         }
 473                         --hlen;                 /* account for type byte */
 474                         datalen = 0;
 475
 476 /* Bail if "l" bytes of data are not left or were not captured  */
 477 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 478
 479                         switch (opt) {
 480
 481                         case TCPOPT_MAXSEG:
 482                                 (void)printf("mss");
 483                                 datalen = 2;
 484                                 LENCHECK(datalen);
 485                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 486
 487                                 break;
 488
 489                         case TCPOPT_EOL:
 490                                 (void)printf("eol");
 491                                 break;
 492
 493                         case TCPOPT_NOP:
 494                                 (void)printf("nop");
 495                                 break;
 496
 497                         case TCPOPT_WSCALE:
 498                                 (void)printf("wscale");
 499                                 datalen = 1;
 500                                 LENCHECK(datalen);
 501                                 (void)printf(" %u", *cp);
 502                                 break;
 503
 504                         case TCPOPT_SACKOK:
 505                                 (void)printf("sackOK");
 506                                 break;
 507
 508                         case TCPOPT_SACK:
 509                                 datalen = len - 2;
 510                                 if (datalen % 8 != 0) {
 511                                         (void)printf("malformed sack");
 512                                 } else {
 513                                         u_int32_t s, e;
 514
 515                                         (void)printf("sack %d ", datalen / 8);
 516                                         for (i = 0; i < datalen; i += 8) {
 517                                                 LENCHECK(i + 4);
 518                                                 s = EXTRACT_32BITS(cp + i);
 519                                                 LENCHECK(i + 8);
 520                                                 e = EXTRACT_32BITS(cp + i + 4);
 521                                                 if (threv) {
 522                                                         s -= thseq;
 523                                                         e -= thseq;
 524                                                 } else {
 525                                                         s -= thack;
 526                                                         e -= thack;
 527                                                 }
 528                                                 (void)printf("{%u:%u}", s, e);
 529                                         }
 530                                 }
 531                                 break;
 532
 533                         case TCPOPT_ECHO:
 534                                 (void)printf("echo");
 535                                 datalen = 4;
 536                                 LENCHECK(datalen);
 537                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 538                                 break;
 539
 540                         case TCPOPT_ECHOREPLY:
 541                                 (void)printf("echoreply");
 542                                 datalen = 4;
 543                                 LENCHECK(datalen);
 544                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 545                                 break;
 546
 547                         case TCPOPT_TIMESTAMP:
 548                                 (void)printf("timestamp");
 549                                 datalen = 8;
 550                                 LENCHECK(4);
 551                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 552                                 LENCHECK(datalen);
 553                                 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
 554                                 break;
 555
 556                         case TCPOPT_CC:
 557                                 (void)printf("cc");
 558                                 datalen = 4;
 559                                 LENCHECK(datalen);
 560                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 561                                 break;
 562
 563                         case TCPOPT_CCNEW:
 564                                 (void)printf("ccnew");
 565                                 datalen = 4;
 566                                 LENCHECK(datalen);
 567                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 568                                 break;
 569
 570                         case TCPOPT_CCECHO:
 571                                 (void)printf("ccecho");
 572                                 datalen = 4;
 573                                 LENCHECK(datalen);
 574                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 575                                 break;
 576
 577                         case TCPOPT_SIGNATURE:
 578                                 (void)printf("md5:");
 579                                 datalen = TCP_SIGLEN;
 580                                 LENCHECK(datalen);
 581 #ifdef HAVE_LIBCRYPTO
 582                                 switch (tcp_verify_signature(ip, tp,
 583                                     bp + TH_OFF(tp) * 4, length, cp)) {
 584
 585                                 case SIGNATURE_VALID:
 586                                         (void)printf("valid");
 587                                         break;
 588
 589                                 case SIGNATURE_INVALID:
 590                                         (void)printf("invalid");
 591                                         break;
 592
 593                                 case CANT_CHECK_SIGNATURE:
 594                                         (void)printf("can't check - ");
 595                                         for (i = 0; i < TCP_SIGLEN; ++i)
 596                                                 (void)printf("%02x", cp[i]);
 597                                         break;
 598                                 }
 599 #else
 600                                 for (i = 0; i < TCP_SIGLEN; ++i)
 601                                         (void)printf("%02x", cp[i]);
 602 #endif
 603                                 break;
 604
 605                         case TCPOPT_AUTH:
 606                                 (void)printf("Enhanced Auth: keyid %d", *cp++);
 607                                 datalen = len - 3;
 608                                 for (i = 0; i < datalen; ++i) {
 609                                     LENCHECK(i);
 610                                     (void)printf("%02x", cp[i]);
 611                                 }
 612                             break;
 613
 614                         default:
 615                                 (void)printf("opt-%u:", opt);
 616                                 datalen = len - 2;
 617                                 for (i = 0; i < datalen; ++i) {
 618                                         LENCHECK(i);
 619                                         (void)printf("%02x", cp[i]);
 620                                 }
 621                                 break;
 622                         }
 623
 624                         /* Account for data printed */
 625                         cp += datalen;
 626                         hlen -= datalen;
 627
 628                         /* Check specification against observed length */
 629                         ++datalen;                      /* option octet */
 630                         if (!ZEROLENOPT(opt))
 631                                 ++datalen;              /* size octet */
 632                         if (datalen != len)
 633                                 (void)printf("[len %d]", len);
 634                         ch = ',';
 635                         if (opt == TCPOPT_EOL)
 636                                 break;
 637                 }
 638                 putchar('>');
 639         }
 640
 641         if (length <= 0)
 642                 return;
 643
 644         /*
 645          * Decode payload if necessary.
 646          */
 647         bp += TH_OFF(tp) * 4;
 648         if (flags & TH_RST) {
 649                 if (vflag)
 650                         print_tcp_rst_data(bp, length);
 651         } else {
 652                 if (sport == TELNET_PORT || dport == TELNET_PORT) {
 653                         if (!qflag && vflag)
 654                                 telnet_print(bp, length);
 655                 } else if (sport == BGP_PORT || dport == BGP_PORT)
 656                         bgp_print(bp, length);
 657                 else if (sport == PPTP_PORT || dport == PPTP_PORT)
 658                         pptp_print(bp);
 659 #ifdef TCPDUMP_DO_SMB
 660                 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 661                         nbt_tcp_print(bp, length);
 662 #endif
 663                 else if (sport == BEEP_PORT || dport == BEEP_PORT)
 664                         beep_print(bp, length);
 665                 else if (length > 2 &&
 666                     (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 667                      sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 668                         /*
 669                          * TCP DNS query has 2byte length at the head.
 670                          * XXX packet could be unaligned, it can go strange
 671                          */
 672                         ns_print(bp + 2, length - 2, 0);
 673                 } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 674                         msdp_print(bp, length);
 675                 }
 676                 else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 677                         ldp_print(bp, length);
 678                 }
 679         }
 680         return;
 681 bad:
 682         fputs("[bad opt]", stdout);
 683         if (ch != '\0')
 684                 putchar('>');
 685         return;
 686 trunc:
 687         fputs("[|tcp]", stdout);
 688         if (ch != '\0')
 689                 putchar('>');
 690 }
 691
 692 /*
 693  * RFC1122 says the following on data in RST segments:
 694  *
 695  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 696  *
 697  *            A TCP SHOULD allow a received RST segment to include data.
 698  *
 699  *            DISCUSSION
 700  *                 It has been suggested that a RST segment could contain
 701  *                 ASCII text that encoded and explained the cause of the
 702  *                 RST.  No standard has yet been established for such
 703  *                 data.
 704  *
 705  */
 706
 707 static void
 708 print_tcp_rst_data(register const u_char *sp, u_int length)
 709 {
 710         int c;
 711
 712         if (TTEST2(*sp, length))
 713                 printf(" [RST");
 714         else
 715                 printf(" [!RST");
 716         if (length > MAX_RST_DATA_LEN) {
 717                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 718                 putchar('+');                   /* indicate we truncate */
 719         }
 720         putchar(' ');
 721         while (length-- && sp <= snapend) {
 722                 c = *sp++;
 723                 safeputchar(c);
 724         }
 725         putchar(']');
 726 }
 727
 728 #ifdef HAVE_LIBCRYPTO
 729 static int
 730 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 731     const u_char *data, int length, const u_char *rcvsig)
 732 {
 733         struct tcphdr tp1;
 734         u_char sig[TCP_SIGLEN];
 735         char zero_proto = 0;
 736         MD5_CTX ctx;
 737         u_int16_t savecsum, tlen;
 738 #ifdef INET6
 739         struct ip6_hdr *ip6;
 740 #endif
 741         u_int32_t len32;
 742         u_int8_t nxt;
 743
 744         tp1 = *tp;
 745
 746         if (tcpmd5secret == NULL)
 747                 return (CANT_CHECK_SIGNATURE);
 748
 749         MD5_Init(&ctx);
 750         /*
 751          * Step 1: Update MD5 hash with IP pseudo-header.
 752          */
 753         if (IP_V(ip) == 4) {
 754                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 755                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 756                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 757                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 758                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 759                 tlen = htons(tlen);
 760                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 761 #ifdef INET6
 762         } else if (IP_V(ip) == 6) {
 763                 ip6 = (struct ip6_hdr *)ip;
 764                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 765                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 766                 len32 = htonl(ntohs(ip6->ip6_plen));
 767                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 768                 nxt = 0;
 769                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 770                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 771                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 772                 nxt = IPPROTO_TCP;
 773                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 774 #endif
 775         } else
 776                 return (CANT_CHECK_SIGNATURE);
 777
 778         /*
 779          * Step 2: Update MD5 hash with TCP header, excluding options.
 780          * The TCP checksum must be set to zero.
 781          */
 782         savecsum = tp1.th_sum;
 783         tp1.th_sum = 0;
 784         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 785         tp1.th_sum = savecsum;
 786         /*
 787          * Step 3: Update MD5 hash with TCP segment data, if present.
 788          */
 789         if (length > 0)
 790                 MD5_Update(&ctx, data, length);
 791         /*
 792          * Step 4: Update MD5 hash with shared secret.
 793          */
 794         MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
 795         MD5_Final(sig, &ctx);
 796
 797         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 798                 return (SIGNATURE_VALID);
 799         else
 800                 return (SIGNATURE_INVALID);
 801 }
 802 #endif /* HAVE_LIBCRYPTO */