The Tcpdump Group git mirrors - tcpdump/blob - print-tcp.c

   1 /*      $NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky Exp $     */
   2
   3 /*
   4  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Copyright (c) 1999-2004 The tcpdump.org project
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that: (1) source code distributions
  11  * retain the above copyright notice and this paragraph in its entirety, (2)
  12  * distributions including binary code include the above copyright notice and
  13  * this paragraph in its entirety in the documentation or other materials
  14  * provided with the distribution, and (3) all advertising materials mentioning
  15  * features or use of this software display the following acknowledgement:
  16  * ``This product includes software developed by the University of California,
  17  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  18  * the University nor the names of its contributors may be used to endorse
  19  * or promote products derived from this software without specific prior
  20  * written permission.
  21  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  22  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  23  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  24  */
  25
  26 #ifndef lint
  27 static const char rcsid[] _U_ =
  28 "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.135 2008-11-09 23:35:03 mcr Exp $ (LBL)";
  29 #else
  30 __RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $");
  31 #endif
  32
  33 #ifdef HAVE_CONFIG_H
  34 #include "config.h"
  35 #endif
  36
  37 #include <tcpdump-stdinc.h>
  38
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #include "interface.h"
  44 #include "addrtoname.h"
  45 #include "extract.h"
  46
  47 #include "tcp.h"
  48
  49 #include "ip.h"
  50 #ifdef INET6
  51 #include "ip6.h"
  52 #endif
  53 #include "ipproto.h"
  54 #include "rpc_auth.h"
  55 #include "rpc_msg.h"
  56
  57 #include "nameser.h"
  58
  59 #ifdef HAVE_LIBCRYPTO
  60 #include <openssl/md5.h>
  61 #include <signature.h>
  62
  63 static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
  64                                 const u_char *data, int length, const u_char *rcvsig);
  65 #endif
  66
  67 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  68
  69 #define MAX_RST_DATA_LEN        30
  70
  71
  72 struct tha {
  73 #ifndef INET6
  74         struct in_addr src;
  75         struct in_addr dst;
  76 #else
  77         struct in6_addr src;
  78         struct in6_addr dst;
  79 #endif /*INET6*/
  80         u_int port;
  81 };
  82
  83 struct tcp_seq_hash {
  84         struct tcp_seq_hash *nxt;
  85         struct tha addr;
  86         tcp_seq seq;
  87         tcp_seq ack;
  88 };
  89
  90 #define TSEQ_HASHSIZE 919
  91
  92 /* These tcp optinos do not have the size octet */
  93 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
  94
  95 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
  96
  97 struct tok tcp_flag_values[] = {
  98         { TH_FIN, "F" },
  99         { TH_SYN, "S" },
 100         { TH_RST, "R" },
 101         { TH_PUSH, "P" },
 102         { TH_ACK, "." },
 103         { TH_URG, "U" },
 104         { TH_ECNECHO, "E" },
 105         { TH_CWR, "W" },
 106         { 0, NULL }
 107 };
 108
 109 struct tok tcp_option_values[] = {
 110         { TCPOPT_EOL, "eol" },
 111         { TCPOPT_NOP, "nop" },
 112         { TCPOPT_MAXSEG, "mss" },
 113         { TCPOPT_WSCALE, "wscale" },
 114         { TCPOPT_SACKOK, "sackOK" },
 115         { TCPOPT_SACK, "sack" },
 116         { TCPOPT_ECHO, "echo" },
 117         { TCPOPT_ECHOREPLY, "echoreply" },
 118         { TCPOPT_TIMESTAMP, "TS" },
 119         { TCPOPT_CC, "cc" },
 120         { TCPOPT_CCNEW, "ccnew" },
 121         { TCPOPT_CCECHO, "" },
 122         { TCPOPT_SIGNATURE, "md5" },
 123         { TCPOPT_AUTH, "enhanced auth" },
 124         { TCPOPT_UTO, "uto" },
 125         { 0, NULL }
 126 };
 127
 128 static int tcp_cksum(register const struct ip *ip,
 129                      register const struct tcphdr *tp,
 130                      register u_int len)
 131 {
 132         union phu {
 133                 struct phdr {
 134                         u_int32_t src;
 135                         u_int32_t dst;
 136                         u_char mbz;
 137                         u_char proto;
 138                         u_int16_t len;
 139                 } ph;
 140                 u_int16_t pa[6];
 141         } phu;
 142         const u_int16_t *sp;
 143
 144         /* pseudo-header.. */
 145         phu.ph.len = htons((u_int16_t)len);
 146         phu.ph.mbz = 0;
 147         phu.ph.proto = IPPROTO_TCP;
 148         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 149         if (IP_HL(ip) == 5)
 150                 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 151         else
 152                 phu.ph.dst = ip_finddst(ip);
 153
 154         sp = &phu.pa[0];
 155         return in_cksum((u_short *)tp, len,
 156                         sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
 157 }
 158
 159 #ifdef INET6
 160 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 161                       u_int len)
 162 {
 163         size_t i;
 164         u_int32_t sum = 0;
 165         union {
 166                 struct {
 167                         struct in6_addr ph_src;
 168                         struct in6_addr ph_dst;
 169                         u_int32_t       ph_len;
 170                         u_int8_t        ph_zero[3];
 171                         u_int8_t        ph_nxt;
 172                 } ph;
 173                 u_int16_t pa[20];
 174         } phu;
 175
 176         /* pseudo-header */
 177         memset(&phu, 0, sizeof(phu));
 178         phu.ph.ph_src = ip6->ip6_src;
 179         phu.ph.ph_dst = ip6->ip6_dst;
 180         phu.ph.ph_len = htonl(len);
 181         phu.ph.ph_nxt = IPPROTO_TCP;
 182
 183         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 184                 sum += phu.pa[i];
 185
 186         return in_cksum((u_short *)tp, len, sum);
 187 }
 188 #endif
 189
 190 void
 191 tcp_print(register const u_char *bp, register u_int length,
 192           register const u_char *bp2, int fragmented)
 193 {
 194         register const struct tcphdr *tp;
 195         register const struct ip *ip;
 196         register u_char flags;
 197         register u_int hlen;
 198         register char ch;
 199         u_int16_t sport, dport, win, urp;
 200         u_int32_t seq, ack, thseq, thack;
 201         u_int utoval;
 202         int threv;
 203 #ifdef INET6
 204         register const struct ip6_hdr *ip6;
 205 #endif
 206
 207         tp = (struct tcphdr *)bp;
 208         ip = (struct ip *)bp2;
 209 #ifdef INET6
 210         if (IP_V(ip) == 6)
 211                 ip6 = (struct ip6_hdr *)bp2;
 212         else
 213                 ip6 = NULL;
 214 #endif /*INET6*/
 215         ch = '\0';
 216         if (!TTEST(tp->th_dport)) {
 217                 (void)printf("%s > %s: [|tcp]",
 218                              ipaddr_string(&ip->ip_src),
 219                              ipaddr_string(&ip->ip_dst));
 220                 return;
 221         }
 222
 223         sport = EXTRACT_16BITS(&tp->th_sport);
 224         dport = EXTRACT_16BITS(&tp->th_dport);
 225
 226         hlen = TH_OFF(tp) * 4;
 227
 228         /*
 229          * If data present, header length valid, and NFS port used,
 230          * assume NFS.
 231          * Pass offset of data plus 4 bytes for RPC TCP msg length
 232          * to NFS print routines.
 233          */
 234         if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
 235             (length - hlen) >= 4) {
 236                 u_char *fraglenp;
 237                 u_int32_t fraglen;
 238                 register struct sunrpc_msg *rp;
 239                 enum sunrpc_msg_type direction;
 240
 241                 fraglenp = (u_char *)tp + hlen;
 242                 if (TTEST2(*fraglenp, 4)) {
 243                         fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
 244                         if (fraglen > (length - hlen) - 4)
 245                                 fraglen = (length - hlen) - 4;
 246                         rp = (struct sunrpc_msg *)(fraglenp + 4);
 247                         if (TTEST(rp->rm_direction)) {
 248                                 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
 249                                 if (dport == NFS_PORT &&
 250                                     direction == SUNRPC_CALL) {
 251                                         nfsreq_print((u_char *)rp, fraglen,
 252                                             (u_char *)ip);
 253                                         return;
 254                                 }
 255                                 if (sport == NFS_PORT &&
 256                                     direction == SUNRPC_REPLY) {
 257                                         nfsreply_print((u_char *)rp, fraglen,
 258                                             (u_char *)ip);
 259                                         return;
 260                                 }
 261                         }
 262                 }
 263         }
 264 #ifdef INET6
 265         if (ip6) {
 266                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 267                         (void)printf("%s.%s > %s.%s: ",
 268                                      ip6addr_string(&ip6->ip6_src),
 269                                      tcpport_string(sport),
 270                                      ip6addr_string(&ip6->ip6_dst),
 271                                      tcpport_string(dport));
 272                 } else {
 273                         (void)printf("%s > %s: ",
 274                                      tcpport_string(sport), tcpport_string(dport));
 275                 }
 276         } else
 277 #endif /*INET6*/
 278         {
 279                 if (ip->ip_p == IPPROTO_TCP) {
 280                         (void)printf("%s.%s > %s.%s: ",
 281                                      ipaddr_string(&ip->ip_src),
 282                                      tcpport_string(sport),
 283                                      ipaddr_string(&ip->ip_dst),
 284                                      tcpport_string(dport));
 285                 } else {
 286                         (void)printf("%s > %s: ",
 287                                      tcpport_string(sport), tcpport_string(dport));
 288                 }
 289         }
 290
 291         if (hlen < sizeof(*tp)) {
 292                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 293                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 294                 return;
 295         }
 296
 297         TCHECK(*tp);
 298
 299         seq = EXTRACT_32BITS(&tp->th_seq);
 300         ack = EXTRACT_32BITS(&tp->th_ack);
 301         win = EXTRACT_16BITS(&tp->th_win);
 302         urp = EXTRACT_16BITS(&tp->th_urp);
 303
 304         if (qflag) {
 305                 (void)printf("tcp %d", length - hlen);
 306                 if (hlen > length) {
 307                         (void)printf(" [bad hdr length %u - too long, > %u]",
 308                                      hlen, length);
 309                 }
 310                 return;
 311         }
 312
 313         flags = tp->th_flags;
 314         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 315
 316         if (!Sflag && (flags & TH_ACK)) {
 317                 register struct tcp_seq_hash *th;
 318                 const void *src, *dst;
 319                 register int rev;
 320                 struct tha tha;
 321                 /*
 322                  * Find (or record) the initial sequence numbers for
 323                  * this conversation.  (we pick an arbitrary
 324                  * collating order so there's only one entry for
 325                  * both directions).
 326                  */
 327 #ifdef INET6
 328                 memset(&tha, 0, sizeof(tha));
 329                 rev = 0;
 330                 if (ip6) {
 331                         src = &ip6->ip6_src;
 332                         dst = &ip6->ip6_dst;
 333                         if (sport > dport)
 334                                 rev = 1;
 335                         else if (sport == dport) {
 336                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 337                                         rev = 1;
 338                         }
 339                         if (rev) {
 340                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 341                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 342                                 tha.port = dport << 16 | sport;
 343                         } else {
 344                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 345                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 346                                 tha.port = sport << 16 | dport;
 347                         }
 348                 } else {
 349                         src = &ip->ip_src;
 350                         dst = &ip->ip_dst;
 351                         if (sport > dport)
 352                                 rev = 1;
 353                         else if (sport == dport) {
 354                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 355                                         rev = 1;
 356                         }
 357                         if (rev) {
 358                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 359                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 360                                 tha.port = dport << 16 | sport;
 361                         } else {
 362                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 363                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 364                                 tha.port = sport << 16 | dport;
 365                         }
 366                 }
 367 #else
 368                 rev = 0;
 369                 src = &ip->ip_src;
 370                 dst = &ip->ip_dst;
 371                 if (sport > dport)
 372                         rev = 1;
 373                 else if (sport == dport) {
 374                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 375                                 rev = 1;
 376                 }
 377                 if (rev) {
 378                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 379                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 380                         tha.port = dport << 16 | sport;
 381                 } else {
 382                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 383                         memcpy(&tha.src, src, sizeof ip->ip_src);
 384                         tha.port = sport << 16 | dport;
 385                 }
 386 #endif
 387
 388                 threv = rev;
 389                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 390                      th->nxt; th = th->nxt)
 391                         if (memcmp((char *)&tha, (char *)&th->addr,
 392                                    sizeof(th->addr)) == 0)
 393                                 break;
 394
 395                 if (!th->nxt || (flags & TH_SYN)) {
 396                         /* didn't find it or new conversation */
 397                         if (th->nxt == NULL) {
 398                                 th->nxt = (struct tcp_seq_hash *)
 399                                         calloc(1, sizeof(*th));
 400                                 if (th->nxt == NULL)
 401                                         error("tcp_print: calloc");
 402                         }
 403                         th->addr = tha;
 404                         if (rev)
 405                                 th->ack = seq, th->seq = ack - 1;
 406                         else
 407                                 th->seq = seq, th->ack = ack - 1;
 408                 } else {
 409                         if (rev)
 410                                 seq -= th->ack, ack -= th->seq;
 411                         else
 412                                 seq -= th->seq, ack -= th->ack;
 413                 }
 414
 415                 thseq = th->seq;
 416                 thack = th->ack;
 417         } else {
 418                 /*fool gcc*/
 419                 thseq = thack = threv = 0;
 420         }
 421         if (hlen > length) {
 422                 (void)printf(" [bad hdr length %u - too long, > %u]",
 423                              hlen, length);
 424                 return;
 425         }
 426
 427         if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 428                 u_int16_t sum, tcp_sum;
 429                 if (TTEST2(tp->th_sport, length)) {
 430                         sum = tcp_cksum(ip, tp, length);
 431
 432                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 433                         if (sum != 0) {
 434                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 435                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 436                         } else
 437                                 (void)printf(" (correct)");
 438                 }
 439         }
 440 #ifdef INET6
 441         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 442                 u_int16_t sum,tcp_sum;
 443                 if (TTEST2(tp->th_sport, length)) {
 444                         sum = tcp6_cksum(ip6, tp, length);
 445                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 446                         if (sum != 0) {
 447                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 448                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 449                         } else
 450                                 (void)printf(" (correct)");
 451
 452                 }
 453         }
 454 #endif
 455
 456         length -= hlen;
 457         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 458                 (void)printf(", seq %u", seq);
 459
 460                 if (length > 0) {
 461                         (void)printf(":%u", seq + length);
 462                 }
 463         }
 464
 465         if (flags & TH_ACK) {
 466                 (void)printf(", ack %u", ack);
 467         }
 468
 469         (void)printf(", win %d", win);
 470
 471         if (flags & TH_URG)
 472                 (void)printf(", urg %d", urp);
 473         /*
 474          * Handle any options.
 475          */
 476         if (hlen > sizeof(*tp)) {
 477                 register const u_char *cp;
 478                 register u_int i, opt, datalen;
 479                 register u_int len;
 480
 481                 hlen -= sizeof(*tp);
 482                 cp = (const u_char *)tp + sizeof(*tp);
 483                 printf(", options [");
 484                 while (hlen > 0) {
 485                         if (ch != '\0')
 486                                 putchar(ch);
 487                         TCHECK(*cp);
 488                         opt = *cp++;
 489                         if (ZEROLENOPT(opt))
 490                                 len = 1;
 491                         else {
 492                                 TCHECK(*cp);
 493                                 len = *cp++;    /* total including type, len */
 494                                 if (len < 2 || len > hlen)
 495                                         goto bad;
 496                                 --hlen;         /* account for length byte */
 497                         }
 498                         --hlen;                 /* account for type byte */
 499                         datalen = 0;
 500
 501 /* Bail if "l" bytes of data are not left or were not captured  */
 502 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 503
 504
 505                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 506
 507                         switch (opt) {
 508
 509                         case TCPOPT_MAXSEG:
 510                                 datalen = 2;
 511                                 LENCHECK(datalen);
 512                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 513                                 break;
 514
 515                         case TCPOPT_WSCALE:
 516                                 datalen = 1;
 517                                 LENCHECK(datalen);
 518                                 (void)printf(" %u", *cp);
 519                                 break;
 520
 521                         case TCPOPT_SACK:
 522                                 datalen = len - 2;
 523                                 if (datalen % 8 != 0) {
 524                                         (void)printf("malformed sack");
 525                                 } else {
 526                                         u_int32_t s, e;
 527
 528                                         (void)printf(" %d ", datalen / 8);
 529                                         for (i = 0; i < datalen; i += 8) {
 530                                                 LENCHECK(i + 4);
 531                                                 s = EXTRACT_32BITS(cp + i);
 532                                                 LENCHECK(i + 8);
 533                                                 e = EXTRACT_32BITS(cp + i + 4);
 534                                                 if (threv) {
 535                                                         s -= thseq;
 536                                                         e -= thseq;
 537                                                 } else {
 538                                                         s -= thack;
 539                                                         e -= thack;
 540                                                 }
 541                                                 (void)printf("{%u:%u}", s, e);
 542                                         }
 543                                 }
 544                                 break;
 545
 546                         case TCPOPT_CC:
 547                         case TCPOPT_CCNEW:
 548                         case TCPOPT_CCECHO:
 549                         case TCPOPT_ECHO:
 550                         case TCPOPT_ECHOREPLY:
 551
 552                                 /*
 553                                  * those options share their semantics.
 554                                  * fall through
 555                                  */
 556                                 datalen = 4;
 557                                 LENCHECK(datalen);
 558                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 559                                 break;
 560
 561                         case TCPOPT_TIMESTAMP:
 562                                 datalen = 8;
 563                                 LENCHECK(datalen);
 564                                 (void)printf(" val %u ecr %u",
 565                                              EXTRACT_32BITS(cp),
 566                                              EXTRACT_32BITS(cp + 4));
 567                                 break;
 568
 569                         case TCPOPT_SIGNATURE:
 570                                 datalen = TCP_SIGLEN;
 571                                 LENCHECK(datalen);
 572 #ifdef HAVE_LIBCRYPTO
 573                                 switch (tcp_verify_signature(ip, tp,
 574                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 575
 576                                 case SIGNATURE_VALID:
 577                                         (void)printf("valid");
 578                                         break;
 579
 580                                 case SIGNATURE_INVALID:
 581                                         (void)printf("invalid");
 582                                         break;
 583
 584                                 case CANT_CHECK_SIGNATURE:
 585                                         (void)printf("can't check - ");
 586                                         for (i = 0; i < TCP_SIGLEN; ++i)
 587                                                 (void)printf("%02x", cp[i]);
 588                                         break;
 589                                 }
 590 #else
 591                                 for (i = 0; i < TCP_SIGLEN; ++i)
 592                                         (void)printf("%02x", cp[i]);
 593 #endif
 594                                 break;
 595
 596                         case TCPOPT_AUTH:
 597                                 (void)printf("keyid %d", *cp++);
 598                                 datalen = len - 3;
 599                                 for (i = 0; i < datalen; ++i) {
 600                                         LENCHECK(i);
 601                                         (void)printf("%02x", cp[i]);
 602                                 }
 603                                 break;
 604
 605
 606                         case TCPOPT_EOL:
 607                         case TCPOPT_NOP:
 608                         case TCPOPT_SACKOK:
 609                                 /*
 610                                  * Nothing interesting.
 611                                  * fall through
 612                                  */
 613                                 break;
 614
 615                         case TCPOPT_UTO:
 616                                 datalen = 2;
 617                                 LENCHECK(datalen);
 618                                 utoval = EXTRACT_16BITS(cp);
 619                                 (void)printf("0x%x", utoval);
 620                                 if (utoval & 0x0001)
 621                                         utoval = (utoval >> 1) * 60;
 622                                 else
 623                                         utoval >>= 1;
 624                                 (void)printf(" %u", utoval);
 625                                 break;
 626
 627                         default:
 628                                 datalen = len - 2;
 629                                 for (i = 0; i < datalen; ++i) {
 630                                         LENCHECK(i);
 631                                         (void)printf("%02x", cp[i]);
 632                                 }
 633                                 break;
 634                         }
 635
 636                         /* Account for data printed */
 637                         cp += datalen;
 638                         hlen -= datalen;
 639
 640                         /* Check specification against observed length */
 641                         ++datalen;                      /* option octet */
 642                         if (!ZEROLENOPT(opt))
 643                                 ++datalen;              /* size octet */
 644                         if (datalen != len)
 645                                 (void)printf("[len %d]", len);
 646                         ch = ',';
 647                         if (opt == TCPOPT_EOL)
 648                                 break;
 649                 }
 650                 putchar(']');
 651         }
 652
 653         /*
 654          * Print length field before crawling down the stack.
 655          */
 656         printf(", length %u", length);
 657
 658         if (length <= 0)
 659                 return;
 660
 661         /*
 662          * Decode payload if necessary.
 663          */
 664         bp += TH_OFF(tp) * 4;
 665         if ((flags & TH_RST) && vflag) {
 666                 print_tcp_rst_data(bp, length);
 667                 return;
 668         }
 669
 670         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 671                 if (!qflag && vflag)
 672                         telnet_print(bp, length);
 673         } else if (sport == BGP_PORT || dport == BGP_PORT)
 674                 bgp_print(bp, length);
 675         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 676                 pptp_print(bp);
 677 #ifdef TCPDUMP_DO_SMB
 678         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 679                 nbt_tcp_print(bp, length);
 680         else if (sport == SMB_PORT || dport == SMB_PORT)
 681                 smb_tcp_print(bp, length);
 682 #endif
 683         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 684                 beep_print(bp, length);
 685         else if (length > 2 &&
 686                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 687                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 688                 /*
 689                  * TCP DNS query has 2byte length at the head.
 690                  * XXX packet could be unaligned, it can go strange
 691                  */
 692                 ns_print(bp + 2, length - 2, 0);
 693         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 694                 msdp_print(bp, length);
 695         }
 696         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 697                 ldp_print(bp, length);
 698         }
 699
 700         return;
 701  bad:
 702         fputs("[bad opt]", stdout);
 703         if (ch != '\0')
 704                 putchar('>');
 705         return;
 706  trunc:
 707         fputs("[|tcp]", stdout);
 708         if (ch != '\0')
 709                 putchar('>');
 710 }
 711
 712 /*
 713  * RFC1122 says the following on data in RST segments:
 714  *
 715  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 716  *
 717  *            A TCP SHOULD allow a received RST segment to include data.
 718  *
 719  *            DISCUSSION
 720  *                 It has been suggested that a RST segment could contain
 721  *                 ASCII text that encoded and explained the cause of the
 722  *                 RST.  No standard has yet been established for such
 723  *                 data.
 724  *
 725  */
 726
 727 static void
 728 print_tcp_rst_data(register const u_char *sp, u_int length)
 729 {
 730         int c;
 731
 732         if (TTEST2(*sp, length))
 733                 printf(" [RST");
 734         else
 735                 printf(" [!RST");
 736         if (length > MAX_RST_DATA_LEN) {
 737                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 738                 putchar('+');                   /* indicate we truncate */
 739         }
 740         putchar(' ');
 741         while (length-- && sp <= snapend) {
 742                 c = *sp++;
 743                 safeputchar(c);
 744         }
 745         putchar(']');
 746 }
 747
 748 #ifdef HAVE_LIBCRYPTO
 749 static int
 750 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 751                      const u_char *data, int length, const u_char *rcvsig)
 752 {
 753         struct tcphdr tp1;
 754         u_char sig[TCP_SIGLEN];
 755         char zero_proto = 0;
 756         MD5_CTX ctx;
 757         u_int16_t savecsum, tlen;
 758 #ifdef INET6
 759         struct ip6_hdr *ip6;
 760         u_int32_t len32;
 761         u_int8_t nxt;
 762 #endif
 763
 764         if (data + length > snapend) {
 765                 printf("snaplen too short, ");
 766                 return (CANT_CHECK_SIGNATURE);
 767         }
 768
 769         tp1 = *tp;
 770
 771         if (sigsecret == NULL) {
 772                 printf("shared secret not supplied with -M, ");
 773                 return (CANT_CHECK_SIGNATURE);
 774         }
 775
 776         MD5_Init(&ctx);
 777         /*
 778          * Step 1: Update MD5 hash with IP pseudo-header.
 779          */
 780         if (IP_V(ip) == 4) {
 781                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 782                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 783                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 784                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 785                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 786                 tlen = htons(tlen);
 787                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 788 #ifdef INET6
 789         } else if (IP_V(ip) == 6) {
 790                 ip6 = (struct ip6_hdr *)ip;
 791                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 792                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 793                 len32 = htonl(ntohs(ip6->ip6_plen));
 794                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 795                 nxt = 0;
 796                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 797                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 798                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 799                 nxt = IPPROTO_TCP;
 800                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 801 #endif
 802         } else {
 803 #ifdef INET6
 804                 printf("IP version not 4 or 6, ");
 805 #else
 806                 printf("IP version not 4, ");
 807 #endif
 808                 return (CANT_CHECK_SIGNATURE);
 809         }
 810
 811         /*
 812          * Step 2: Update MD5 hash with TCP header, excluding options.
 813          * The TCP checksum must be set to zero.
 814          */
 815         savecsum = tp1.th_sum;
 816         tp1.th_sum = 0;
 817         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 818         tp1.th_sum = savecsum;
 819         /*
 820          * Step 3: Update MD5 hash with TCP segment data, if present.
 821          */
 822         if (length > 0)
 823                 MD5_Update(&ctx, data, length);
 824         /*
 825          * Step 4: Update MD5 hash with shared secret.
 826          */
 827         MD5_Update(&ctx, sigsecret, strlen(sigsecret));
 828         MD5_Final(sig, &ctx);
 829
 830         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 831                 return (SIGNATURE_VALID);
 832         else
 833                 return (SIGNATURE_INVALID);
 834 }
 835 #endif /* HAVE_LIBCRYPTO */
 836
 837 /*
 838  * Local Variables:
 839  * c-style: whitesmith
 840  * c-basic-offset: 8
 841  * End:
 842  */