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 1.130 2007-08-29 02:31:44 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
  62 #define SIGNATURE_VALID         0
  63 #define SIGNATURE_INVALID       1
  64 #define CANT_CHECK_SIGNATURE    2
  65
  66 static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
  67                                 const u_char *data, int length, const u_char *rcvsig);
  68 #endif
  69
  70 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  71
  72 #define MAX_RST_DATA_LEN        30
  73
  74
  75 struct tha {
  76 #ifndef INET6
  77         struct in_addr src;
  78         struct in_addr dst;
  79 #else
  80         struct in6_addr src;
  81         struct in6_addr dst;
  82 #endif /*INET6*/
  83         u_int port;
  84 };
  85
  86 struct tcp_seq_hash {
  87         struct tcp_seq_hash *nxt;
  88         struct tha addr;
  89         tcp_seq seq;
  90         tcp_seq ack;
  91 };
  92
  93 #define TSEQ_HASHSIZE 919
  94
  95 /* These tcp optinos do not have the size octet */
  96 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
  97
  98 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
  99
 100 struct tok tcp_flag_values[] = {
 101         { TH_FIN, "F" },
 102         { TH_SYN, "S" },
 103         { TH_RST, "R" },
 104         { TH_PUSH, "P" },
 105         { TH_ACK, "." },
 106         { TH_URG, "U" },
 107         { TH_ECNECHO, "E" },
 108         { TH_CWR, "W" },
 109         { 0, NULL }
 110 };
 111
 112 struct tok tcp_option_values[] = {
 113         { TCPOPT_EOL, "eol" },
 114         { TCPOPT_NOP, "nop" },
 115         { TCPOPT_MAXSEG, "mss" },
 116         { TCPOPT_WSCALE, "wscale" },
 117         { TCPOPT_SACKOK, "sackOK" },
 118         { TCPOPT_SACK, "sack" },
 119         { TCPOPT_ECHO, "echo" },
 120         { TCPOPT_ECHOREPLY, "echoreply" },
 121         { TCPOPT_TIMESTAMP, "TS" },
 122         { TCPOPT_CC, "cc" },
 123         { TCPOPT_CCNEW, "ccnew" },
 124         { TCPOPT_CCECHO, "" },
 125         { TCPOPT_SIGNATURE, "md5" },
 126         { TCPOPT_AUTH, "enhanced auth" },
 127         { 0, NULL }
 128 };
 129
 130 static int tcp_cksum(register const struct ip *ip,
 131                      register const struct tcphdr *tp,
 132                      register u_int len)
 133 {
 134         union phu {
 135                 struct phdr {
 136                         u_int32_t src;
 137                         u_int32_t dst;
 138                         u_char mbz;
 139                         u_char proto;
 140                         u_int16_t len;
 141                 } ph;
 142                 u_int16_t pa[6];
 143         } phu;
 144         const u_int16_t *sp;
 145
 146         /* pseudo-header.. */
 147         phu.ph.len = htons((u_int16_t)len);
 148         phu.ph.mbz = 0;
 149         phu.ph.proto = IPPROTO_TCP;
 150         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 151         if (IP_HL(ip) == 5)
 152                 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 153         else
 154                 phu.ph.dst = ip_finddst(ip);
 155
 156         sp = &phu.pa[0];
 157         return in_cksum((u_short *)tp, len,
 158                         sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
 159 }
 160
 161 #ifdef INET6
 162 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 163                       u_int len)
 164 {
 165         size_t i;
 166         u_int32_t sum = 0;
 167         union {
 168                 struct {
 169                         struct in6_addr ph_src;
 170                         struct in6_addr ph_dst;
 171                         u_int32_t       ph_len;
 172                         u_int8_t        ph_zero[3];
 173                         u_int8_t        ph_nxt;
 174                 } ph;
 175                 u_int16_t pa[20];
 176         } phu;
 177
 178         /* pseudo-header */
 179         memset(&phu, 0, sizeof(phu));
 180         phu.ph.ph_src = ip6->ip6_src;
 181         phu.ph.ph_dst = ip6->ip6_dst;
 182         phu.ph.ph_len = htonl(len);
 183         phu.ph.ph_nxt = IPPROTO_TCP;
 184
 185         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 186                 sum += phu.pa[i];
 187
 188         return in_cksum((u_short *)tp, len, sum);
 189 }
 190 #endif
 191
 192 void
 193 tcp_print(register const u_char *bp, register u_int length,
 194           register const u_char *bp2, int fragmented)
 195 {
 196         register const struct tcphdr *tp;
 197         register const struct ip *ip;
 198         register u_char flags;
 199         register u_int hlen;
 200         register char ch;
 201         u_int16_t sport, dport, win, urp;
 202         u_int32_t seq, ack, thseq, thack;
 203         int threv;
 204 #ifdef INET6
 205         register const struct ip6_hdr *ip6;
 206 #endif
 207
 208         tp = (struct tcphdr *)bp;
 209         ip = (struct ip *)bp2;
 210 #ifdef INET6
 211         if (IP_V(ip) == 6)
 212                 ip6 = (struct ip6_hdr *)bp2;
 213         else
 214                 ip6 = NULL;
 215 #endif /*INET6*/
 216         ch = '\0';
 217         if (!TTEST(tp->th_dport)) {
 218                 (void)printf("%s > %s: [|tcp]",
 219                              ipaddr_string(&ip->ip_src),
 220                              ipaddr_string(&ip->ip_dst));
 221                 return;
 222         }
 223
 224         sport = EXTRACT_16BITS(&tp->th_sport);
 225         dport = EXTRACT_16BITS(&tp->th_dport);
 226
 227         hlen = TH_OFF(tp) * 4;
 228
 229         /*
 230          * If data present, header length valid, and NFS port used,
 231          * assume NFS.
 232          * Pass offset of data plus 4 bytes for RPC TCP msg length
 233          * to NFS print routines.
 234          */
 235         if (!qflag && hlen >= sizeof(*tp) && hlen <= length) {
 236                 if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg) <= snapend &&
 237                     dport == NFS_PORT) {
 238                         nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
 239                                      (u_char *)ip);
 240                         return;
 241                 } else if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg)
 242                            <= snapend &&
 243                            sport == NFS_PORT) {
 244                         nfsreply_print((u_char *)tp + hlen + 4, length - hlen,
 245                                        (u_char *)ip);
 246                         return;
 247                 }
 248         }
 249 #ifdef INET6
 250         if (ip6) {
 251                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 252                         (void)printf("%s.%s > %s.%s: ",
 253                                      ip6addr_string(&ip6->ip6_src),
 254                                      tcpport_string(sport),
 255                                      ip6addr_string(&ip6->ip6_dst),
 256                                      tcpport_string(dport));
 257                 } else {
 258                         (void)printf("%s > %s: ",
 259                                      tcpport_string(sport), tcpport_string(dport));
 260                 }
 261         } else
 262 #endif /*INET6*/
 263         {
 264                 if (ip->ip_p == IPPROTO_TCP) {
 265                         (void)printf("%s.%s > %s.%s: ",
 266                                      ipaddr_string(&ip->ip_src),
 267                                      tcpport_string(sport),
 268                                      ipaddr_string(&ip->ip_dst),
 269                                      tcpport_string(dport));
 270                 } else {
 271                         (void)printf("%s > %s: ",
 272                                      tcpport_string(sport), tcpport_string(dport));
 273                 }
 274         }
 275
 276         if (hlen < sizeof(*tp)) {
 277                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 278                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 279                 return;
 280         }
 281
 282         TCHECK(*tp);
 283
 284         seq = EXTRACT_32BITS(&tp->th_seq);
 285         ack = EXTRACT_32BITS(&tp->th_ack);
 286         win = EXTRACT_16BITS(&tp->th_win);
 287         urp = EXTRACT_16BITS(&tp->th_urp);
 288
 289         if (qflag) {
 290                 (void)printf("tcp %d", length - hlen);
 291                 if (hlen > length) {
 292                         (void)printf(" [bad hdr length %u - too long, > %u]",
 293                                      hlen, length);
 294                 }
 295                 return;
 296         }
 297
 298         flags = tp->th_flags;
 299         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 300
 301         if (!Sflag && (flags & TH_ACK)) {
 302                 register struct tcp_seq_hash *th;
 303                 const void *src, *dst;
 304                 register int rev;
 305                 struct tha tha;
 306                 /*
 307                  * Find (or record) the initial sequence numbers for
 308                  * this conversation.  (we pick an arbitrary
 309                  * collating order so there's only one entry for
 310                  * both directions).
 311                  */
 312 #ifdef INET6
 313                 memset(&tha, 0, sizeof(tha));
 314                 rev = 0;
 315                 if (ip6) {
 316                         src = &ip6->ip6_src;
 317                         dst = &ip6->ip6_dst;
 318                         if (sport > dport)
 319                                 rev = 1;
 320                         else if (sport == dport) {
 321                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 322                                         rev = 1;
 323                         }
 324                         if (rev) {
 325                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 326                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 327                                 tha.port = dport << 16 | sport;
 328                         } else {
 329                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 330                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 331                                 tha.port = sport << 16 | dport;
 332                         }
 333                 } else {
 334                         src = &ip->ip_src;
 335                         dst = &ip->ip_dst;
 336                         if (sport > dport)
 337                                 rev = 1;
 338                         else if (sport == dport) {
 339                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 340                                         rev = 1;
 341                         }
 342                         if (rev) {
 343                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 344                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 345                                 tha.port = dport << 16 | sport;
 346                         } else {
 347                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 348                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 349                                 tha.port = sport << 16 | dport;
 350                         }
 351                 }
 352 #else
 353                 rev = 0;
 354                 src = &ip->ip_src;
 355                 dst = &ip->ip_dst;
 356                 if (sport > dport)
 357                         rev = 1;
 358                 else if (sport == dport) {
 359                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 360                                 rev = 1;
 361                 }
 362                 if (rev) {
 363                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 364                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 365                         tha.port = dport << 16 | sport;
 366                 } else {
 367                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 368                         memcpy(&tha.src, src, sizeof ip->ip_src);
 369                         tha.port = sport << 16 | dport;
 370                 }
 371 #endif
 372
 373                 threv = rev;
 374                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 375                      th->nxt; th = th->nxt)
 376                         if (memcmp((char *)&tha, (char *)&th->addr,
 377                                    sizeof(th->addr)) == 0)
 378                                 break;
 379
 380                 if (!th->nxt || (flags & TH_SYN)) {
 381                         /* didn't find it or new conversation */
 382                         if (th->nxt == NULL) {
 383                                 th->nxt = (struct tcp_seq_hash *)
 384                                         calloc(1, sizeof(*th));
 385                                 if (th->nxt == NULL)
 386                                         error("tcp_print: calloc");
 387                         }
 388                         th->addr = tha;
 389                         if (rev)
 390                                 th->ack = seq, th->seq = ack - 1;
 391                         else
 392                                 th->seq = seq, th->ack = ack - 1;
 393                 } else {
 394                         if (rev)
 395                                 seq -= th->ack, ack -= th->seq;
 396                         else
 397                                 seq -= th->seq, ack -= th->ack;
 398                 }
 399
 400                 thseq = th->seq;
 401                 thack = th->ack;
 402         } else {
 403                 /*fool gcc*/
 404                 thseq = thack = threv = 0;
 405         }
 406         if (hlen > length) {
 407                 (void)printf(" [bad hdr length %u - too long, > %u]",
 408                              hlen, length);
 409                 return;
 410         }
 411
 412         if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 413                 u_int16_t sum, tcp_sum;
 414                 if (TTEST2(tp->th_sport, length)) {
 415                         sum = tcp_cksum(ip, tp, length);
 416
 417                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 418                         if (sum != 0) {
 419                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 420                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 421                         } else
 422                                 (void)printf(" (correct)");
 423                 }
 424         }
 425 #ifdef INET6
 426         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 427                 u_int16_t sum,tcp_sum;
 428                 if (TTEST2(tp->th_sport, length)) {
 429                         sum = tcp6_cksum(ip6, tp, length);
 430                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 431                         if (sum != 0) {
 432                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 433                                 (void)printf(" (incorrect (-> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 434                         } else
 435                                 (void)printf(" (correct)");
 436
 437                 }
 438         }
 439 #endif
 440
 441         length -= hlen;
 442         if (vflag > 1 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 443                 (void)printf(", seq %u", seq);
 444
 445                 if (length > 0) {
 446                         (void)printf(":%u", seq + length);
 447                 }
 448         }
 449
 450         if (flags & TH_ACK) {
 451                 (void)printf(", ack %u", ack);
 452         }
 453
 454         (void)printf(", win %d", win);
 455
 456         if (flags & TH_URG)
 457                 (void)printf(", urg %d", urp);
 458         /*
 459          * Handle any options.
 460          */
 461         if (hlen > sizeof(*tp)) {
 462                 register const u_char *cp;
 463                 register u_int i, opt, datalen;
 464                 register u_int len;
 465
 466                 hlen -= sizeof(*tp);
 467                 cp = (const u_char *)tp + sizeof(*tp);
 468                 printf(", options [");
 469                 while (hlen > 0) {
 470                         if (ch != '\0')
 471                                 putchar(ch);
 472                         TCHECK(*cp);
 473                         opt = *cp++;
 474                         if (ZEROLENOPT(opt))
 475                                 len = 1;
 476                         else {
 477                                 TCHECK(*cp);
 478                                 len = *cp++;    /* total including type, len */
 479                                 if (len < 2 || len > hlen)
 480                                         goto bad;
 481                                 --hlen;         /* account for length byte */
 482                         }
 483                         --hlen;                 /* account for type byte */
 484                         datalen = 0;
 485
 486 /* Bail if "l" bytes of data are not left or were not captured  */
 487 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 488
 489
 490                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 491
 492                         switch (opt) {
 493
 494                         case TCPOPT_MAXSEG:
 495                                 datalen = 2;
 496                                 LENCHECK(datalen);
 497                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 498                                 break;
 499
 500                         case TCPOPT_WSCALE:
 501                                 datalen = 1;
 502                                 LENCHECK(datalen);
 503                                 (void)printf(" %u", *cp);
 504                                 break;
 505
 506                         case TCPOPT_SACK:
 507                                 datalen = len - 2;
 508                                 if (datalen % 8 != 0) {
 509                                         (void)printf("malformed sack");
 510                                 } else {
 511                                         u_int32_t s, e;
 512
 513                                         (void)printf(" %d ", datalen / 8);
 514                                         for (i = 0; i < datalen; i += 8) {
 515                                                 LENCHECK(i + 4);
 516                                                 s = EXTRACT_32BITS(cp + i);
 517                                                 LENCHECK(i + 8);
 518                                                 e = EXTRACT_32BITS(cp + i + 4);
 519                                                 if (threv) {
 520                                                         s -= thseq;
 521                                                         e -= thseq;
 522                                                 } else {
 523                                                         s -= thack;
 524                                                         e -= thack;
 525                                                 }
 526                                                 (void)printf("{%u:%u}", s, e);
 527                                         }
 528                                 }
 529                                 break;
 530
 531                         case TCPOPT_CC:
 532                         case TCPOPT_CCNEW:
 533                         case TCPOPT_CCECHO:
 534                         case TCPOPT_ECHO:
 535                         case TCPOPT_ECHOREPLY:
 536
 537                                 /*
 538                                  * those options share their semantics.
 539                                  * fall through
 540                                  */
 541                                 datalen = 4;
 542                                 LENCHECK(datalen);
 543                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 544                                 break;
 545
 546                         case TCPOPT_TIMESTAMP:
 547                                 datalen = 8;
 548                                 LENCHECK(datalen);
 549                                 (void)printf(" val %u ecr %u",
 550                                              EXTRACT_32BITS(cp),
 551                                              EXTRACT_32BITS(cp + 4));
 552                                 break;
 553
 554                         case TCPOPT_SIGNATURE:
 555                                 datalen = TCP_SIGLEN;
 556                                 LENCHECK(datalen);
 557 #ifdef HAVE_LIBCRYPTO
 558                                 switch (tcp_verify_signature(ip, tp,
 559                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 560
 561                                 case SIGNATURE_VALID:
 562                                         (void)printf("valid");
 563                                         break;
 564
 565                                 case SIGNATURE_INVALID:
 566                                         (void)printf("invalid");
 567                                         break;
 568
 569                                 case CANT_CHECK_SIGNATURE:
 570                                         (void)printf("can't check - ");
 571                                         for (i = 0; i < TCP_SIGLEN; ++i)
 572                                                 (void)printf("%02x", cp[i]);
 573                                         break;
 574                                 }
 575 #else
 576                                 for (i = 0; i < TCP_SIGLEN; ++i)
 577                                         (void)printf("%02x", cp[i]);
 578 #endif
 579                                 break;
 580
 581                         case TCPOPT_AUTH:
 582                                 (void)printf("keyid %d", *cp++);
 583                                 datalen = len - 3;
 584                                 for (i = 0; i < datalen; ++i) {
 585                                         LENCHECK(i);
 586                                         (void)printf("%02x", cp[i]);
 587                                 }
 588                                 break;
 589
 590
 591                         case TCPOPT_EOL:
 592                         case TCPOPT_NOP:
 593                         case TCPOPT_SACKOK:
 594                                 /*
 595                                  * Nothing interesting.
 596                                  * fall through
 597                                  */
 598                                 break;
 599
 600                         default:
 601                                 datalen = len - 2;
 602                                 for (i = 0; i < datalen; ++i) {
 603                                         LENCHECK(i);
 604                                         (void)printf("%02x", cp[i]);
 605                                 }
 606                                 break;
 607                         }
 608
 609                         /* Account for data printed */
 610                         cp += datalen;
 611                         hlen -= datalen;
 612
 613                         /* Check specification against observed length */
 614                         ++datalen;                      /* option octet */
 615                         if (!ZEROLENOPT(opt))
 616                                 ++datalen;              /* size octet */
 617                         if (datalen != len)
 618                                 (void)printf("[len %d]", len);
 619                         ch = ',';
 620                         if (opt == TCPOPT_EOL)
 621                                 break;
 622                 }
 623                 putchar(']');
 624         }
 625
 626         /*
 627          * Print length field before crawling down the stack.
 628          */
 629         printf(", length %u", length);
 630
 631         if (length <= 0)
 632                 return;
 633
 634         /*
 635          * Decode payload if necessary.
 636          */
 637         bp += TH_OFF(tp) * 4;
 638         if ((flags & TH_RST) && vflag) {
 639                 print_tcp_rst_data(bp, length);
 640                 return;
 641         }
 642
 643         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 644                 if (!qflag && vflag)
 645                         telnet_print(bp, length);
 646         } else if (sport == BGP_PORT || dport == BGP_PORT)
 647                 bgp_print(bp, length);
 648         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 649                 pptp_print(bp);
 650 #ifdef TCPDUMP_DO_SMB
 651         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 652                 nbt_tcp_print(bp, length);
 653 #endif
 654         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 655                 beep_print(bp, length);
 656         else if (length > 2 &&
 657                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 658                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 659                 /*
 660                  * TCP DNS query has 2byte length at the head.
 661                  * XXX packet could be unaligned, it can go strange
 662                  */
 663                 ns_print(bp + 2, length - 2, 0);
 664         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 665                 msdp_print(bp, length);
 666         }
 667         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 668                 ldp_print(bp, length);
 669         }
 670
 671         return;
 672  bad:
 673         fputs("[bad opt]", stdout);
 674         if (ch != '\0')
 675                 putchar('>');
 676         return;
 677  trunc:
 678         fputs("[|tcp]", stdout);
 679         if (ch != '\0')
 680                 putchar('>');
 681 }
 682
 683 /*
 684  * RFC1122 says the following on data in RST segments:
 685  *
 686  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 687  *
 688  *            A TCP SHOULD allow a received RST segment to include data.
 689  *
 690  *            DISCUSSION
 691  *                 It has been suggested that a RST segment could contain
 692  *                 ASCII text that encoded and explained the cause of the
 693  *                 RST.  No standard has yet been established for such
 694  *                 data.
 695  *
 696  */
 697
 698 static void
 699 print_tcp_rst_data(register const u_char *sp, u_int length)
 700 {
 701         int c;
 702
 703         if (TTEST2(*sp, length))
 704                 printf(" [RST");
 705         else
 706                 printf(" [!RST");
 707         if (length > MAX_RST_DATA_LEN) {
 708                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 709                 putchar('+');                   /* indicate we truncate */
 710         }
 711         putchar(' ');
 712         while (length-- && sp <= snapend) {
 713                 c = *sp++;
 714                 safeputchar(c);
 715         }
 716         putchar(']');
 717 }
 718
 719 #ifdef HAVE_LIBCRYPTO
 720 static int
 721 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 722                      const u_char *data, int length, const u_char *rcvsig)
 723 {
 724         struct tcphdr tp1;
 725         u_char sig[TCP_SIGLEN];
 726         char zero_proto = 0;
 727         MD5_CTX ctx;
 728         u_int16_t savecsum, tlen;
 729 #ifdef INET6
 730         struct ip6_hdr *ip6;
 731         u_int32_t len32;
 732         u_int8_t nxt;
 733 #endif
 734
 735         tp1 = *tp;
 736
 737         if (tcpmd5secret == NULL)
 738                 return (CANT_CHECK_SIGNATURE);
 739
 740         MD5_Init(&ctx);
 741         /*
 742          * Step 1: Update MD5 hash with IP pseudo-header.
 743          */
 744         if (IP_V(ip) == 4) {
 745                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 746                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 747                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 748                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 749                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 750                 tlen = htons(tlen);
 751                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 752 #ifdef INET6
 753         } else if (IP_V(ip) == 6) {
 754                 ip6 = (struct ip6_hdr *)ip;
 755                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 756                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 757                 len32 = htonl(ntohs(ip6->ip6_plen));
 758                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 759                 nxt = 0;
 760                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 761                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 762                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 763                 nxt = IPPROTO_TCP;
 764                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 765 #endif
 766         } else
 767                 return (CANT_CHECK_SIGNATURE);
 768
 769         /*
 770          * Step 2: Update MD5 hash with TCP header, excluding options.
 771          * The TCP checksum must be set to zero.
 772          */
 773         savecsum = tp1.th_sum;
 774         tp1.th_sum = 0;
 775         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 776         tp1.th_sum = savecsum;
 777         /*
 778          * Step 3: Update MD5 hash with TCP segment data, if present.
 779          */
 780         if (length > 0)
 781                 MD5_Update(&ctx, data, length);
 782         /*
 783          * Step 4: Update MD5 hash with shared secret.
 784          */
 785         MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
 786         MD5_Final(sig, &ctx);
 787
 788         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 789                 return (SIGNATURE_VALID);
 790         else
 791                 return (SIGNATURE_INVALID);
 792 }
 793 #endif /* HAVE_LIBCRYPTO */
 794
 795 /*
 796  * Local Variables:
 797  * c-style: whitesmith
 798  * c-basic-offset: 8
 799  * End:
 800  */