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         { TCPOPT_MPTCP, "MPTCP" },
 126         { 0, NULL }
 127 };
 128
 129 static int tcp_cksum(register const struct ip *ip,
 130                      register const struct tcphdr *tp,
 131                      register u_int len)
 132 {
 133         return (nextproto4_cksum(ip, (const u_int8_t *)tp, len,
 134             IPPROTO_TCP));
 135 }
 136
 137 void
 138 tcp_print(register const u_char *bp, register u_int length,
 139           register const u_char *bp2, int fragmented)
 140 {
 141         register const struct tcphdr *tp;
 142         register const struct ip *ip;
 143         register u_char flags;
 144         register u_int hlen;
 145         register char ch;
 146         u_int16_t sport, dport, win, urp;
 147         u_int32_t seq, ack, thseq, thack;
 148         u_int utoval;
 149         int threv;
 150 #ifdef INET6
 151         register const struct ip6_hdr *ip6;
 152 #endif
 153
 154         tp = (struct tcphdr *)bp;
 155         ip = (struct ip *)bp2;
 156 #ifdef INET6
 157         if (IP_V(ip) == 6)
 158                 ip6 = (struct ip6_hdr *)bp2;
 159         else
 160                 ip6 = NULL;
 161 #endif /*INET6*/
 162         ch = '\0';
 163         if (!TTEST(tp->th_dport)) {
 164                 (void)printf("%s > %s: [|tcp]",
 165                              ipaddr_string(&ip->ip_src),
 166                              ipaddr_string(&ip->ip_dst));
 167                 return;
 168         }
 169
 170         sport = EXTRACT_16BITS(&tp->th_sport);
 171         dport = EXTRACT_16BITS(&tp->th_dport);
 172
 173         hlen = TH_OFF(tp) * 4;
 174
 175         /*
 176          * If data present, header length valid, and NFS port used,
 177          * assume NFS.
 178          * Pass offset of data plus 4 bytes for RPC TCP msg length
 179          * to NFS print routines.
 180          */
 181         if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
 182             (length - hlen) >= 4) {
 183                 u_char *fraglenp;
 184                 u_int32_t fraglen;
 185                 register struct sunrpc_msg *rp;
 186                 enum sunrpc_msg_type direction;
 187
 188                 fraglenp = (u_char *)tp + hlen;
 189                 if (TTEST2(*fraglenp, 4)) {
 190                         fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
 191                         if (fraglen > (length - hlen) - 4)
 192                                 fraglen = (length - hlen) - 4;
 193                         rp = (struct sunrpc_msg *)(fraglenp + 4);
 194                         if (TTEST(rp->rm_direction)) {
 195                                 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
 196                                 if (dport == NFS_PORT &&
 197                                     direction == SUNRPC_CALL) {
 198                                         nfsreq_print((u_char *)rp, fraglen,
 199                                             (u_char *)ip);
 200                                         return;
 201                                 }
 202                                 if (sport == NFS_PORT &&
 203                                     direction == SUNRPC_REPLY) {
 204                                         nfsreply_print((u_char *)rp, fraglen,
 205                                             (u_char *)ip);
 206                                         return;
 207                                 }
 208                         }
 209                 }
 210         }
 211 #ifdef INET6
 212         if (ip6) {
 213                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 214                         (void)printf("%s.%s > %s.%s: ",
 215                                      ip6addr_string(&ip6->ip6_src),
 216                                      tcpport_string(sport),
 217                                      ip6addr_string(&ip6->ip6_dst),
 218                                      tcpport_string(dport));
 219                 } else {
 220                         (void)printf("%s > %s: ",
 221                                      tcpport_string(sport), tcpport_string(dport));
 222                 }
 223         } else
 224 #endif /*INET6*/
 225         {
 226                 if (ip->ip_p == IPPROTO_TCP) {
 227                         (void)printf("%s.%s > %s.%s: ",
 228                                      ipaddr_string(&ip->ip_src),
 229                                      tcpport_string(sport),
 230                                      ipaddr_string(&ip->ip_dst),
 231                                      tcpport_string(dport));
 232                 } else {
 233                         (void)printf("%s > %s: ",
 234                                      tcpport_string(sport), tcpport_string(dport));
 235                 }
 236         }
 237
 238         if (hlen < sizeof(*tp)) {
 239                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 240                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 241                 return;
 242         }
 243
 244         TCHECK(*tp);
 245
 246         seq = EXTRACT_32BITS(&tp->th_seq);
 247         ack = EXTRACT_32BITS(&tp->th_ack);
 248         win = EXTRACT_16BITS(&tp->th_win);
 249         urp = EXTRACT_16BITS(&tp->th_urp);
 250
 251         if (qflag) {
 252                 (void)printf("tcp %d", length - hlen);
 253                 if (hlen > length) {
 254                         (void)printf(" [bad hdr length %u - too long, > %u]",
 255                                      hlen, length);
 256                 }
 257                 return;
 258         }
 259
 260         flags = tp->th_flags;
 261         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 262
 263         if (!Sflag && (flags & TH_ACK)) {
 264                 register struct tcp_seq_hash *th;
 265                 const void *src, *dst;
 266                 register int rev;
 267                 struct tha tha;
 268                 /*
 269                  * Find (or record) the initial sequence numbers for
 270                  * this conversation.  (we pick an arbitrary
 271                  * collating order so there's only one entry for
 272                  * both directions).
 273                  */
 274 #ifdef INET6
 275                 rev = 0;
 276                 if (ip6) {
 277                         src = &ip6->ip6_src;
 278                         dst = &ip6->ip6_dst;
 279                         if (sport > dport)
 280                                 rev = 1;
 281                         else if (sport == dport) {
 282                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 283                                         rev = 1;
 284                         }
 285                         if (rev) {
 286                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 287                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 288                                 tha.port = dport << 16 | sport;
 289                         } else {
 290                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 291                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 292                                 tha.port = sport << 16 | dport;
 293                         }
 294                 } else {
 295                         /*
 296                          * Zero out the tha structure; the src and dst
 297                          * fields are big enough to hold an IPv6
 298                          * address, but we only have IPv4 addresses
 299                          * and thus must clear out the remaining 124
 300                          * bits.
 301                          *
 302                          * XXX - should we just clear those bytes after
 303                          * copying the IPv4 addresses, rather than
 304                          * zeroing out the entire structure and then
 305                          * overwriting some of the zeroes?
 306                          *
 307                          * XXX - this could fail if we see TCP packets
 308                          * with an IPv6 address with the lower 124 bits
 309                          * all zero and also see TCP packes with an
 310                          * IPv4 address with the same 32 bits as the
 311                          * upper 32 bits of the IPv6 address in question.
 312                          * Can that happen?  Is it likely enough to be
 313                          * an issue?
 314                          */
 315                         memset(&tha, 0, sizeof(tha));
 316                         src = &ip->ip_src;
 317                         dst = &ip->ip_dst;
 318                         if (sport > dport)
 319                                 rev = 1;
 320                         else if (sport == dport) {
 321                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 322                                         rev = 1;
 323                         }
 324                         if (rev) {
 325                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 326                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 327                                 tha.port = dport << 16 | sport;
 328                         } else {
 329                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 330                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 331                                 tha.port = sport << 16 | dport;
 332                         }
 333                 }
 334 #else
 335                 rev = 0;
 336                 src = &ip->ip_src;
 337                 dst = &ip->ip_dst;
 338                 if (sport > dport)
 339                         rev = 1;
 340                 else if (sport == dport) {
 341                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 342                                 rev = 1;
 343                 }
 344                 if (rev) {
 345                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 346                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 347                         tha.port = dport << 16 | sport;
 348                 } else {
 349                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 350                         memcpy(&tha.src, src, sizeof ip->ip_src);
 351                         tha.port = sport << 16 | dport;
 352                 }
 353 #endif
 354
 355                 threv = rev;
 356                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 357                      th->nxt; th = th->nxt)
 358                         if (memcmp((char *)&tha, (char *)&th->addr,
 359                                    sizeof(th->addr)) == 0)
 360                                 break;
 361
 362                 if (!th->nxt || (flags & TH_SYN)) {
 363                         /* didn't find it or new conversation */
 364                         if (th->nxt == NULL) {
 365                                 th->nxt = (struct tcp_seq_hash *)
 366                                         calloc(1, sizeof(*th));
 367                                 if (th->nxt == NULL)
 368                                         error("tcp_print: calloc");
 369                         }
 370                         th->addr = tha;
 371                         if (rev)
 372                                 th->ack = seq, th->seq = ack - 1;
 373                         else
 374                                 th->seq = seq, th->ack = ack - 1;
 375                 } else {
 376                         if (rev)
 377                                 seq -= th->ack, ack -= th->seq;
 378                         else
 379                                 seq -= th->seq, ack -= th->ack;
 380                 }
 381
 382                 thseq = th->seq;
 383                 thack = th->ack;
 384         } else {
 385                 /*fool gcc*/
 386                 thseq = thack = threv = 0;
 387         }
 388         if (hlen > length) {
 389                 (void)printf(" [bad hdr length %u - too long, > %u]",
 390                              hlen, length);
 391                 return;
 392         }
 393
 394         if (vflag && !Kflag && !fragmented) {
 395                 /* Check the checksum, if possible. */
 396                 u_int16_t sum, tcp_sum;
 397
 398                 if (IP_V(ip) == 4) {
 399                         if (TTEST2(tp->th_sport, length)) {
 400                                 sum = tcp_cksum(ip, tp, length);
 401                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 402
 403                                 (void)printf(", cksum 0x%04x", tcp_sum);
 404                                 if (sum != 0)
 405                                         (void)printf(" (incorrect -> 0x%04x)",
 406                                             in_cksum_shouldbe(tcp_sum, sum));
 407                                 else
 408                                         (void)printf(" (correct)");
 409                         }
 410                 }
 411 #ifdef INET6
 412                 else if (IP_V(ip) == 6 && ip6->ip6_plen) {
 413                         if (TTEST2(tp->th_sport, length)) {
 414                                 sum = nextproto6_cksum(ip6, (const u_int8_t *)tp, length, IPPROTO_TCP);
 415                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 416
 417                                 (void)printf(", cksum 0x%04x", tcp_sum);
 418                                 if (sum != 0)
 419                                         (void)printf(" (incorrect -> 0x%04x)",
 420                                             in_cksum_shouldbe(tcp_sum, sum));
 421                                 else
 422                                         (void)printf(" (correct)");
 423
 424                         }
 425                 }
 426 #endif
 427         }
 428
 429         length -= hlen;
 430         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 431                 (void)printf(", seq %u", seq);
 432
 433                 if (length > 0) {
 434                         (void)printf(":%u", seq + length);
 435                 }
 436         }
 437
 438         if (flags & TH_ACK) {
 439                 (void)printf(", ack %u", ack);
 440         }
 441
 442         (void)printf(", win %d", win);
 443
 444         if (flags & TH_URG)
 445                 (void)printf(", urg %d", urp);
 446         /*
 447          * Handle any options.
 448          */
 449         if (hlen > sizeof(*tp)) {
 450                 register const u_char *cp;
 451                 register u_int i, opt, datalen;
 452                 register u_int len;
 453
 454                 hlen -= sizeof(*tp);
 455                 cp = (const u_char *)tp + sizeof(*tp);
 456                 printf(", options [");
 457                 while (hlen > 0) {
 458                         if (ch != '\0')
 459                                 putchar(ch);
 460                         TCHECK(*cp);
 461                         opt = *cp++;
 462                         if (ZEROLENOPT(opt))
 463                                 len = 1;
 464                         else {
 465                                 TCHECK(*cp);
 466                                 len = *cp++;    /* total including type, len */
 467                                 if (len < 2 || len > hlen)
 468                                         goto bad;
 469                                 --hlen;         /* account for length byte */
 470                         }
 471                         --hlen;                 /* account for type byte */
 472                         datalen = 0;
 473
 474 /* Bail if "l" bytes of data are not left or were not captured  */
 475 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 476
 477
 478                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 479
 480                         switch (opt) {
 481
 482                         case TCPOPT_MAXSEG:
 483                                 datalen = 2;
 484                                 LENCHECK(datalen);
 485                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 486                                 break;
 487
 488                         case TCPOPT_WSCALE:
 489                                 datalen = 1;
 490                                 LENCHECK(datalen);
 491                                 (void)printf(" %u", *cp);
 492                                 break;
 493
 494                         case TCPOPT_SACK:
 495                                 datalen = len - 2;
 496                                 if (datalen % 8 != 0) {
 497                                         (void)printf("malformed sack");
 498                                 } else {
 499                                         u_int32_t s, e;
 500
 501                                         (void)printf(" %d ", datalen / 8);
 502                                         for (i = 0; i < datalen; i += 8) {
 503                                                 LENCHECK(i + 4);
 504                                                 s = EXTRACT_32BITS(cp + i);
 505                                                 LENCHECK(i + 8);
 506                                                 e = EXTRACT_32BITS(cp + i + 4);
 507                                                 if (threv) {
 508                                                         s -= thseq;
 509                                                         e -= thseq;
 510                                                 } else {
 511                                                         s -= thack;
 512                                                         e -= thack;
 513                                                 }
 514                                                 (void)printf("{%u:%u}", s, e);
 515                                         }
 516                                 }
 517                                 break;
 518
 519                         case TCPOPT_CC:
 520                         case TCPOPT_CCNEW:
 521                         case TCPOPT_CCECHO:
 522                         case TCPOPT_ECHO:
 523                         case TCPOPT_ECHOREPLY:
 524
 525                                 /*
 526                                  * those options share their semantics.
 527                                  * fall through
 528                                  */
 529                                 datalen = 4;
 530                                 LENCHECK(datalen);
 531                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 532                                 break;
 533
 534                         case TCPOPT_TIMESTAMP:
 535                                 datalen = 8;
 536                                 LENCHECK(datalen);
 537                                 (void)printf(" val %u ecr %u",
 538                                              EXTRACT_32BITS(cp),
 539                                              EXTRACT_32BITS(cp + 4));
 540                                 break;
 541
 542                         case TCPOPT_SIGNATURE:
 543                                 datalen = TCP_SIGLEN;
 544                                 LENCHECK(datalen);
 545 #ifdef HAVE_LIBCRYPTO
 546                                 switch (tcp_verify_signature(ip, tp,
 547                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 548
 549                                 case SIGNATURE_VALID:
 550                                         (void)printf("valid");
 551                                         break;
 552
 553                                 case SIGNATURE_INVALID:
 554                                         (void)printf("invalid");
 555                                         break;
 556
 557                                 case CANT_CHECK_SIGNATURE:
 558                                         (void)printf("can't check - ");
 559                                         for (i = 0; i < TCP_SIGLEN; ++i)
 560                                                 (void)printf("%02x", cp[i]);
 561                                         break;
 562                                 }
 563 #else
 564                                 for (i = 0; i < TCP_SIGLEN; ++i)
 565                                         (void)printf("%02x", cp[i]);
 566 #endif
 567                                 break;
 568
 569                         case TCPOPT_AUTH:
 570                                 (void)printf("keyid %d", *cp++);
 571                                 datalen = len - 3;
 572                                 for (i = 0; i < datalen; ++i) {
 573                                         LENCHECK(i);
 574                                         (void)printf("%02x", cp[i]);
 575                                 }
 576                                 break;
 577
 578
 579                         case TCPOPT_EOL:
 580                         case TCPOPT_NOP:
 581                         case TCPOPT_SACKOK:
 582                                 /*
 583                                  * Nothing interesting.
 584                                  * fall through
 585                                  */
 586                                 break;
 587
 588                         case TCPOPT_UTO:
 589                                 datalen = 2;
 590                                 LENCHECK(datalen);
 591                                 utoval = EXTRACT_16BITS(cp);
 592                                 (void)printf("0x%x", utoval);
 593                                 if (utoval & 0x0001)
 594                                         utoval = (utoval >> 1) * 60;
 595                                 else
 596                                         utoval >>= 1;
 597                                 (void)printf(" %u", utoval);
 598                                 break;
 599
 600                         case TCPOPT_MPTCP:
 601                                 datalen = len - 2;
 602                                 if (!mptcp_print(cp-2, len))
 603                                         goto bad;
 604                                 break;
 605
 606                         default:
 607                                 datalen = len - 2;
 608                                 for (i = 0; i < datalen; ++i) {
 609                                         LENCHECK(i);
 610                                         (void)printf("%02x", cp[i]);
 611                                 }
 612                                 break;
 613                         }
 614
 615                         /* Account for data printed */
 616                         cp += datalen;
 617                         hlen -= datalen;
 618
 619                         /* Check specification against observed length */
 620                         ++datalen;                      /* option octet */
 621                         if (!ZEROLENOPT(opt))
 622                                 ++datalen;              /* size octet */
 623                         if (datalen != len)
 624                                 (void)printf("[len %d]", len);
 625                         ch = ',';
 626                         if (opt == TCPOPT_EOL)
 627                                 break;
 628                 }
 629                 putchar(']');
 630         }
 631
 632         /*
 633          * Print length field before crawling down the stack.
 634          */
 635         printf(", length %u", length);
 636
 637         if (length <= 0)
 638                 return;
 639
 640         /*
 641          * Decode payload if necessary.
 642          */
 643         bp += TH_OFF(tp) * 4;
 644         if ((flags & TH_RST) && vflag) {
 645                 print_tcp_rst_data(bp, length);
 646                 return;
 647         }
 648
 649         if (packettype) {
 650                 switch (packettype) {
 651                 case PT_ZMTP1:
 652                         zmtp1_print(bp, length);
 653                         break;
 654                 }
 655                 return;
 656         }
 657
 658         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 659                 if (!qflag && vflag)
 660                         telnet_print(bp, length);
 661         } else if (sport == BGP_PORT || dport == BGP_PORT)
 662                 bgp_print(bp, length);
 663         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 664                 pptp_print(bp);
 665 #ifdef TCPDUMP_DO_SMB
 666         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 667                 nbt_tcp_print(bp, length);
 668         else if (sport == SMB_PORT || dport == SMB_PORT)
 669                 smb_tcp_print(bp, length);
 670 #endif
 671         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 672                 beep_print(bp, length);
 673         else if (length > 2 &&
 674                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 675                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 676                 /*
 677                  * TCP DNS query has 2byte length at the head.
 678                  * XXX packet could be unaligned, it can go strange
 679                  */
 680                 ns_print(bp + 2, length - 2, 0);
 681         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 682                 msdp_print(bp, length);
 683         } else if (sport == RPKI_RTR_PORT || dport == RPKI_RTR_PORT) {
 684                 rpki_rtr_print(bp, length);
 685         }
 686         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 687                 ldp_print(bp, length);
 688         }
 689
 690         return;
 691  bad:
 692         fputs("[bad opt]", stdout);
 693         if (ch != '\0')
 694                 putchar('>');
 695         return;
 696  trunc:
 697         fputs("[|tcp]", stdout);
 698         if (ch != '\0')
 699                 putchar('>');
 700 }
 701
 702 /*
 703  * RFC1122 says the following on data in RST segments:
 704  *
 705  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 706  *
 707  *            A TCP SHOULD allow a received RST segment to include data.
 708  *
 709  *            DISCUSSION
 710  *                 It has been suggested that a RST segment could contain
 711  *                 ASCII text that encoded and explained the cause of the
 712  *                 RST.  No standard has yet been established for such
 713  *                 data.
 714  *
 715  */
 716
 717 static void
 718 print_tcp_rst_data(register const u_char *sp, u_int length)
 719 {
 720         int c;
 721
 722         if (TTEST2(*sp, length))
 723                 printf(" [RST");
 724         else
 725                 printf(" [!RST");
 726         if (length > MAX_RST_DATA_LEN) {
 727                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 728                 putchar('+');                   /* indicate we truncate */
 729         }
 730         putchar(' ');
 731         while (length-- && sp <= snapend) {
 732                 c = *sp++;
 733                 safeputchar(c);
 734         }
 735         putchar(']');
 736 }
 737
 738 #ifdef HAVE_LIBCRYPTO
 739 static int
 740 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 741                      const u_char *data, int length, const u_char *rcvsig)
 742 {
 743         struct tcphdr tp1;
 744         u_char sig[TCP_SIGLEN];
 745         char zero_proto = 0;
 746         MD5_CTX ctx;
 747         u_int16_t savecsum, tlen;
 748 #ifdef INET6
 749         struct ip6_hdr *ip6;
 750         u_int32_t len32;
 751         u_int8_t nxt;
 752 #endif
 753
 754         if (data + length > snapend) {
 755                 printf("snaplen too short, ");
 756                 return (CANT_CHECK_SIGNATURE);
 757         }
 758
 759         tp1 = *tp;
 760
 761         if (sigsecret == NULL) {
 762                 printf("shared secret not supplied with -M, ");
 763                 return (CANT_CHECK_SIGNATURE);
 764         }
 765
 766         MD5_Init(&ctx);
 767         /*
 768          * Step 1: Update MD5 hash with IP pseudo-header.
 769          */
 770         if (IP_V(ip) == 4) {
 771                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 772                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 773                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 774                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 775                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 776                 tlen = htons(tlen);
 777                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 778 #ifdef INET6
 779         } else if (IP_V(ip) == 6) {
 780                 ip6 = (struct ip6_hdr *)ip;
 781                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 782                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 783                 len32 = htonl(EXTRACT_16BITS(&ip6->ip6_plen));
 784                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 785                 nxt = 0;
 786                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 787                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 788                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 789                 nxt = IPPROTO_TCP;
 790                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 791 #endif
 792         } else {
 793 #ifdef INET6
 794                 printf("IP version not 4 or 6, ");
 795 #else
 796                 printf("IP version not 4, ");
 797 #endif
 798                 return (CANT_CHECK_SIGNATURE);
 799         }
 800
 801         /*
 802          * Step 2: Update MD5 hash with TCP header, excluding options.
 803          * The TCP checksum must be set to zero.
 804          */
 805         savecsum = tp1.th_sum;
 806         tp1.th_sum = 0;
 807         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 808         tp1.th_sum = savecsum;
 809         /*
 810          * Step 3: Update MD5 hash with TCP segment data, if present.
 811          */
 812         if (length > 0)
 813                 MD5_Update(&ctx, data, length);
 814         /*
 815          * Step 4: Update MD5 hash with shared secret.
 816          */
 817         MD5_Update(&ctx, sigsecret, strlen(sigsecret));
 818         MD5_Final(sig, &ctx);
 819
 820         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 821                 return (SIGNATURE_VALID);
 822         else
 823                 return (SIGNATURE_INVALID);
 824 }
 825 #endif /* HAVE_LIBCRYPTO */
 826
 827 /*
 828  * Local Variables:
 829  * c-style: whitesmith
 830  * c-basic-offset: 8
 831  * End:
 832  */