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