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 static const 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 static const struct tok tcp_option_values[] = {
 110         { TCPOPT_EOL, "eol" },
 111         { TCPOPT_NOP, "nop" },
 112         { TCPOPT_MAXSEG, "mss" },
 113         { TCPOPT_WSCALE, "wscale" },
 114         { TCPOPT_SACKOK, "sackOK" },
 115         { TCPOPT_SACK, "sack" },
 116         { TCPOPT_ECHO, "echo" },
 117         { TCPOPT_ECHOREPLY, "echoreply" },
 118         { TCPOPT_TIMESTAMP, "TS" },
 119         { TCPOPT_CC, "cc" },
 120         { TCPOPT_CCNEW, "ccnew" },
 121         { TCPOPT_CCECHO, "" },
 122         { TCPOPT_SIGNATURE, "md5" },
 123         { TCPOPT_AUTH, "enhanced auth" },
 124         { TCPOPT_UTO, "uto" },
 125         { TCPOPT_MPTCP, "mptcp" },
 126         { TCPOPT_EXPERIMENT2, "exp" },
 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         return (nextproto4_cksum(ip, (const u_int8_t *)tp, len,
 135             IPPROTO_TCP));
 136 }
 137
 138 void
 139 tcp_print(register const u_char *bp, register u_int length,
 140           register const u_char *bp2, int fragmented)
 141 {
 142         register const struct tcphdr *tp;
 143         register const struct ip *ip;
 144         register u_char flags;
 145         register u_int hlen;
 146         register char ch;
 147         u_int16_t sport, dport, win, urp;
 148         u_int32_t seq, ack, thseq, thack;
 149         u_int utoval;
 150         u_int16_t magic;
 151         int threv;
 152 #ifdef INET6
 153         register const struct ip6_hdr *ip6;
 154 #endif
 155
 156         tp = (struct tcphdr *)bp;
 157         ip = (struct ip *)bp2;
 158 #ifdef INET6
 159         if (IP_V(ip) == 6)
 160                 ip6 = (struct ip6_hdr *)bp2;
 161         else
 162                 ip6 = NULL;
 163 #endif /*INET6*/
 164         ch = '\0';
 165         if (!TTEST(tp->th_dport)) {
 166                 (void)printf("%s > %s: [|tcp]",
 167                              ipaddr_string(&ip->ip_src),
 168                              ipaddr_string(&ip->ip_dst));
 169                 return;
 170         }
 171
 172         sport = EXTRACT_16BITS(&tp->th_sport);
 173         dport = EXTRACT_16BITS(&tp->th_dport);
 174
 175         hlen = TH_OFF(tp) * 4;
 176
 177         /*
 178          * If data present, header length valid, and NFS port used,
 179          * assume NFS.
 180          * Pass offset of data plus 4 bytes for RPC TCP msg length
 181          * to NFS print routines.
 182          */
 183         if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
 184             (length - hlen) >= 4) {
 185                 u_char *fraglenp;
 186                 u_int32_t fraglen;
 187                 register struct sunrpc_msg *rp;
 188                 enum sunrpc_msg_type direction;
 189
 190                 fraglenp = (u_char *)tp + hlen;
 191                 if (TTEST2(*fraglenp, 4)) {
 192                         fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
 193                         if (fraglen > (length - hlen) - 4)
 194                                 fraglen = (length - hlen) - 4;
 195                         rp = (struct sunrpc_msg *)(fraglenp + 4);
 196                         if (TTEST(rp->rm_direction)) {
 197                                 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
 198                                 if (dport == NFS_PORT &&
 199                                     direction == SUNRPC_CALL) {
 200                                         nfsreq_print((u_char *)rp, fraglen,
 201                                             (u_char *)ip);
 202                                         return;
 203                                 }
 204                                 if (sport == NFS_PORT &&
 205                                     direction == SUNRPC_REPLY) {
 206                                         nfsreply_print((u_char *)rp, fraglen,
 207                                             (u_char *)ip);
 208                                         return;
 209                                 }
 210                         }
 211                 }
 212         }
 213 #ifdef INET6
 214         if (ip6) {
 215                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 216                         (void)printf("%s.%s > %s.%s: ",
 217                                      ip6addr_string(&ip6->ip6_src),
 218                                      tcpport_string(sport),
 219                                      ip6addr_string(&ip6->ip6_dst),
 220                                      tcpport_string(dport));
 221                 } else {
 222                         (void)printf("%s > %s: ",
 223                                      tcpport_string(sport), tcpport_string(dport));
 224                 }
 225         } else
 226 #endif /*INET6*/
 227         {
 228                 if (ip->ip_p == IPPROTO_TCP) {
 229                         (void)printf("%s.%s > %s.%s: ",
 230                                      ipaddr_string(&ip->ip_src),
 231                                      tcpport_string(sport),
 232                                      ipaddr_string(&ip->ip_dst),
 233                                      tcpport_string(dport));
 234                 } else {
 235                         (void)printf("%s > %s: ",
 236                                      tcpport_string(sport), tcpport_string(dport));
 237                 }
 238         }
 239
 240         if (hlen < sizeof(*tp)) {
 241                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 242                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 243                 return;
 244         }
 245
 246         TCHECK(*tp);
 247
 248         seq = EXTRACT_32BITS(&tp->th_seq);
 249         ack = EXTRACT_32BITS(&tp->th_ack);
 250         win = EXTRACT_16BITS(&tp->th_win);
 251         urp = EXTRACT_16BITS(&tp->th_urp);
 252
 253         if (qflag) {
 254                 (void)printf("tcp %d", length - hlen);
 255                 if (hlen > length) {
 256                         (void)printf(" [bad hdr length %u - too long, > %u]",
 257                                      hlen, length);
 258                 }
 259                 return;
 260         }
 261
 262         flags = tp->th_flags;
 263         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 264
 265         if (!Sflag && (flags & TH_ACK)) {
 266                 register struct tcp_seq_hash *th;
 267                 const void *src, *dst;
 268                 register int rev;
 269                 struct tha tha;
 270                 /*
 271                  * Find (or record) the initial sequence numbers for
 272                  * this conversation.  (we pick an arbitrary
 273                  * collating order so there's only one entry for
 274                  * both directions).
 275                  */
 276 #ifdef INET6
 277                 rev = 0;
 278                 if (ip6) {
 279                         src = &ip6->ip6_src;
 280                         dst = &ip6->ip6_dst;
 281                         if (sport > dport)
 282                                 rev = 1;
 283                         else if (sport == dport) {
 284                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 285                                         rev = 1;
 286                         }
 287                         if (rev) {
 288                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 289                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 290                                 tha.port = dport << 16 | sport;
 291                         } else {
 292                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 293                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 294                                 tha.port = sport << 16 | dport;
 295                         }
 296                 } else {
 297                         /*
 298                          * Zero out the tha structure; the src and dst
 299                          * fields are big enough to hold an IPv6
 300                          * address, but we only have IPv4 addresses
 301                          * and thus must clear out the remaining 124
 302                          * bits.
 303                          *
 304                          * XXX - should we just clear those bytes after
 305                          * copying the IPv4 addresses, rather than
 306                          * zeroing out the entire structure and then
 307                          * overwriting some of the zeroes?
 308                          *
 309                          * XXX - this could fail if we see TCP packets
 310                          * with an IPv6 address with the lower 124 bits
 311                          * all zero and also see TCP packes with an
 312                          * IPv4 address with the same 32 bits as the
 313                          * upper 32 bits of the IPv6 address in question.
 314                          * Can that happen?  Is it likely enough to be
 315                          * an issue?
 316                          */
 317                         memset(&tha, 0, sizeof(tha));
 318                         src = &ip->ip_src;
 319                         dst = &ip->ip_dst;
 320                         if (sport > dport)
 321                                 rev = 1;
 322                         else if (sport == dport) {
 323                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 324                                         rev = 1;
 325                         }
 326                         if (rev) {
 327                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 328                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 329                                 tha.port = dport << 16 | sport;
 330                         } else {
 331                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 332                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 333                                 tha.port = sport << 16 | dport;
 334                         }
 335                 }
 336 #else
 337                 rev = 0;
 338                 src = &ip->ip_src;
 339                 dst = &ip->ip_dst;
 340                 if (sport > dport)
 341                         rev = 1;
 342                 else if (sport == dport) {
 343                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 344                                 rev = 1;
 345                 }
 346                 if (rev) {
 347                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 348                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 349                         tha.port = dport << 16 | sport;
 350                 } else {
 351                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 352                         memcpy(&tha.src, src, sizeof ip->ip_src);
 353                         tha.port = sport << 16 | dport;
 354                 }
 355 #endif
 356
 357                 threv = rev;
 358                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 359                      th->nxt; th = th->nxt)
 360                         if (memcmp((char *)&tha, (char *)&th->addr,
 361                                    sizeof(th->addr)) == 0)
 362                                 break;
 363
 364                 if (!th->nxt || (flags & TH_SYN)) {
 365                         /* didn't find it or new conversation */
 366                         if (th->nxt == NULL) {
 367                                 th->nxt = (struct tcp_seq_hash *)
 368                                         calloc(1, sizeof(*th));
 369                                 if (th->nxt == NULL)
 370                                         error("tcp_print: calloc");
 371                         }
 372                         th->addr = tha;
 373                         if (rev)
 374                                 th->ack = seq, th->seq = ack - 1;
 375                         else
 376                                 th->seq = seq, th->ack = ack - 1;
 377                 } else {
 378                         if (rev)
 379                                 seq -= th->ack, ack -= th->seq;
 380                         else
 381                                 seq -= th->seq, ack -= th->ack;
 382                 }
 383
 384                 thseq = th->seq;
 385                 thack = th->ack;
 386         } else {
 387                 /*fool gcc*/
 388                 thseq = thack = threv = 0;
 389         }
 390         if (hlen > length) {
 391                 (void)printf(" [bad hdr length %u - too long, > %u]",
 392                              hlen, length);
 393                 return;
 394         }
 395
 396         if (vflag && !Kflag && !fragmented) {
 397                 /* Check the checksum, if possible. */
 398                 u_int16_t sum, tcp_sum;
 399
 400                 if (IP_V(ip) == 4) {
 401                         if (TTEST2(tp->th_sport, length)) {
 402                                 sum = tcp_cksum(ip, tp, length);
 403                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 404
 405                                 (void)printf(", cksum 0x%04x", tcp_sum);
 406                                 if (sum != 0)
 407                                         (void)printf(" (incorrect -> 0x%04x)",
 408                                             in_cksum_shouldbe(tcp_sum, sum));
 409                                 else
 410                                         (void)printf(" (correct)");
 411                         }
 412                 }
 413 #ifdef INET6
 414                 else if (IP_V(ip) == 6 && ip6->ip6_plen) {
 415                         if (TTEST2(tp->th_sport, length)) {
 416                                 sum = nextproto6_cksum(ip6, (const u_int8_t *)tp, length, IPPROTO_TCP);
 417                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 418
 419                                 (void)printf(", cksum 0x%04x", tcp_sum);
 420                                 if (sum != 0)
 421                                         (void)printf(" (incorrect -> 0x%04x)",
 422                                             in_cksum_shouldbe(tcp_sum, sum));
 423                                 else
 424                                         (void)printf(" (correct)");
 425
 426                         }
 427                 }
 428 #endif
 429         }
 430
 431         length -= hlen;
 432         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 433                 (void)printf(", seq %u", seq);
 434
 435                 if (length > 0) {
 436                         (void)printf(":%u", seq + length);
 437                 }
 438         }
 439
 440         if (flags & TH_ACK) {
 441                 (void)printf(", ack %u", ack);
 442         }
 443
 444         (void)printf(", win %d", win);
 445
 446         if (flags & TH_URG)
 447                 (void)printf(", urg %d", urp);
 448         /*
 449          * Handle any options.
 450          */
 451         if (hlen > sizeof(*tp)) {
 452                 register const u_char *cp;
 453                 register u_int i, opt, datalen;
 454                 register u_int len;
 455
 456                 hlen -= sizeof(*tp);
 457                 cp = (const u_char *)tp + sizeof(*tp);
 458                 printf(", options [");
 459                 while (hlen > 0) {
 460                         if (ch != '\0')
 461                                 putchar(ch);
 462                         TCHECK(*cp);
 463                         opt = *cp++;
 464                         if (ZEROLENOPT(opt))
 465                                 len = 1;
 466                         else {
 467                                 TCHECK(*cp);
 468                                 len = *cp++;    /* total including type, len */
 469                                 if (len < 2 || len > hlen)
 470                                         goto bad;
 471                                 --hlen;         /* account for length byte */
 472                         }
 473                         --hlen;                 /* account for type byte */
 474                         datalen = 0;
 475
 476 /* Bail if "l" bytes of data are not left or were not captured  */
 477 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 478
 479
 480                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 481
 482                         switch (opt) {
 483
 484                         case TCPOPT_MAXSEG:
 485                                 datalen = 2;
 486                                 LENCHECK(datalen);
 487                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 488                                 break;
 489
 490                         case TCPOPT_WSCALE:
 491                                 datalen = 1;
 492                                 LENCHECK(datalen);
 493                                 (void)printf(" %u", *cp);
 494                                 break;
 495
 496                         case TCPOPT_SACK:
 497                                 datalen = len - 2;
 498                                 if (datalen % 8 != 0) {
 499                                         (void)printf("malformed sack");
 500                                 } else {
 501                                         u_int32_t s, e;
 502
 503                                         (void)printf(" %d ", datalen / 8);
 504                                         for (i = 0; i < datalen; i += 8) {
 505                                                 LENCHECK(i + 4);
 506                                                 s = EXTRACT_32BITS(cp + i);
 507                                                 LENCHECK(i + 8);
 508                                                 e = EXTRACT_32BITS(cp + i + 4);
 509                                                 if (threv) {
 510                                                         s -= thseq;
 511                                                         e -= thseq;
 512                                                 } else {
 513                                                         s -= thack;
 514                                                         e -= thack;
 515                                                 }
 516                                                 (void)printf("{%u:%u}", s, e);
 517                                         }
 518                                 }
 519                                 break;
 520
 521                         case TCPOPT_CC:
 522                         case TCPOPT_CCNEW:
 523                         case TCPOPT_CCECHO:
 524                         case TCPOPT_ECHO:
 525                         case TCPOPT_ECHOREPLY:
 526
 527                                 /*
 528                                  * those options share their semantics.
 529                                  * fall through
 530                                  */
 531                                 datalen = 4;
 532                                 LENCHECK(datalen);
 533                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 534                                 break;
 535
 536                         case TCPOPT_TIMESTAMP:
 537                                 datalen = 8;
 538                                 LENCHECK(datalen);
 539                                 (void)printf(" val %u ecr %u",
 540                                              EXTRACT_32BITS(cp),
 541                                              EXTRACT_32BITS(cp + 4));
 542                                 break;
 543
 544                         case TCPOPT_SIGNATURE:
 545                                 datalen = TCP_SIGLEN;
 546                                 LENCHECK(datalen);
 547 #ifdef HAVE_LIBCRYPTO
 548                                 switch (tcp_verify_signature(ip, tp,
 549                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 550
 551                                 case SIGNATURE_VALID:
 552                                         (void)printf("valid");
 553                                         break;
 554
 555                                 case SIGNATURE_INVALID:
 556                                         (void)printf("invalid");
 557                                         break;
 558
 559                                 case CANT_CHECK_SIGNATURE:
 560                                         (void)printf("can't check - ");
 561                                         for (i = 0; i < TCP_SIGLEN; ++i)
 562                                                 (void)printf("%02x", cp[i]);
 563                                         break;
 564                                 }
 565 #else
 566                                 for (i = 0; i < TCP_SIGLEN; ++i)
 567                                         (void)printf("%02x", cp[i]);
 568 #endif
 569                                 break;
 570
 571                         case TCPOPT_AUTH:
 572                                 (void)printf("keyid %d", *cp++);
 573                                 datalen = len - 3;
 574                                 for (i = 0; i < datalen; ++i) {
 575                                         LENCHECK(i);
 576                                         (void)printf("%02x", cp[i]);
 577                                 }
 578                                 break;
 579
 580
 581                         case TCPOPT_EOL:
 582                         case TCPOPT_NOP:
 583                         case TCPOPT_SACKOK:
 584                                 /*
 585                                  * Nothing interesting.
 586                                  * fall through
 587                                  */
 588                                 break;
 589
 590                         case TCPOPT_UTO:
 591                                 datalen = 2;
 592                                 LENCHECK(datalen);
 593                                 utoval = EXTRACT_16BITS(cp);
 594                                 (void)printf("0x%x", utoval);
 595                                 if (utoval & 0x0001)
 596                                         utoval = (utoval >> 1) * 60;
 597                                 else
 598                                         utoval >>= 1;
 599                                 (void)printf(" %u", utoval);
 600                                 break;
 601
 602                         case TCPOPT_MPTCP:
 603                                 datalen = len - 2;
 604                                 LENCHECK(datalen);
 605                                 if (!mptcp_print(cp-2, len, flags))
 606                                         goto bad;
 607                                 break;
 608
 609                         case TCPOPT_EXPERIMENT2:
 610                                 datalen = len - 2;
 611                                 LENCHECK(datalen);
 612                                 if (datalen < 2)
 613                                         goto bad;
 614                                 magic = EXTRACT_16BITS(cp);
 615                                 (void)printf("-");
 616
 617                                 switch(magic) {
 618
 619                                 case 0xf989:
 620                                         /* TCP Fast Open: draft-ietf-tcpm-fastopen-04 */
 621                                         if (datalen == 2) {
 622                                                 /* Fast Open Cookie Request */
 623                                                 (void)printf("tfo cookiereq");
 624                                         } else {
 625                                                 /* Fast Open Cookie */
 626                                                 if (datalen % 2 != 0 || datalen < 6 || datalen > 18) {
 627                                                         (void)printf("tfo malformed");
 628                                                 } else {
 629                                                         (void)printf("tfo cookie ");
 630                                                         for (i = 2; i < datalen; ++i)
 631                                                                 (void)printf("%02x", cp[i]);
 632                                                 }
 633                                         }
 634                                         break;
 635
 636                                 default:
 637                                         /* Unknown magic number */
 638                                         (void)printf("%04x", magic);
 639                                         break;
 640                                 }
 641                                 break;
 642
 643                         default:
 644                                 datalen = len - 2;
 645                                 for (i = 0; i < datalen; ++i) {
 646                                         LENCHECK(i);
 647                                         (void)printf("%02x", cp[i]);
 648                                 }
 649                                 break;
 650                         }
 651
 652                         /* Account for data printed */
 653                         cp += datalen;
 654                         hlen -= datalen;
 655
 656                         /* Check specification against observed length */
 657                         ++datalen;                      /* option octet */
 658                         if (!ZEROLENOPT(opt))
 659                                 ++datalen;              /* size octet */
 660                         if (datalen != len)
 661                                 (void)printf("[len %d]", len);
 662                         ch = ',';
 663                         if (opt == TCPOPT_EOL)
 664                                 break;
 665                 }
 666                 putchar(']');
 667         }
 668
 669         /*
 670          * Print length field before crawling down the stack.
 671          */
 672         printf(", length %u", length);
 673
 674         if (length <= 0)
 675                 return;
 676
 677         /*
 678          * Decode payload if necessary.
 679          */
 680         bp += TH_OFF(tp) * 4;
 681         if ((flags & TH_RST) && vflag) {
 682                 print_tcp_rst_data(bp, length);
 683                 return;
 684         }
 685
 686         if (packettype) {
 687                 switch (packettype) {
 688                 case PT_ZMTP1:
 689                         zmtp1_print(bp, length);
 690                         break;
 691                 }
 692                 return;
 693         }
 694
 695         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 696                 if (!qflag && vflag)
 697                         telnet_print(bp, length);
 698         } else if (sport == BGP_PORT || dport == BGP_PORT)
 699                 bgp_print(bp, length);
 700         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 701                 pptp_print(bp);
 702 #ifdef TCPDUMP_DO_SMB
 703         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 704                 nbt_tcp_print(bp, length);
 705         else if (sport == SMB_PORT || dport == SMB_PORT)
 706                 smb_tcp_print(bp, length);
 707 #endif
 708         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 709                 beep_print(bp, length);
 710         else if (sport == OPENFLOW_PORT || dport == OPENFLOW_PORT)
 711                 openflow_print(bp, length);
 712         else if (length > 2 &&
 713                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 714                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 715                 /*
 716                  * TCP DNS query has 2byte length at the head.
 717                  * XXX packet could be unaligned, it can go strange
 718                  */
 719                 ns_print(bp + 2, length - 2, 0);
 720         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 721                 msdp_print(bp, length);
 722         } else if (sport == RPKI_RTR_PORT || dport == RPKI_RTR_PORT) {
 723                 rpki_rtr_print(bp, length);
 724         }
 725         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 726                 ldp_print(bp, length);
 727         }
 728
 729         return;
 730  bad:
 731         fputs("[bad opt]", stdout);
 732         if (ch != '\0')
 733                 putchar('>');
 734         return;
 735  trunc:
 736         fputs("[|tcp]", stdout);
 737         if (ch != '\0')
 738                 putchar('>');
 739 }
 740
 741 /*
 742  * RFC1122 says the following on data in RST segments:
 743  *
 744  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 745  *
 746  *            A TCP SHOULD allow a received RST segment to include data.
 747  *
 748  *            DISCUSSION
 749  *                 It has been suggested that a RST segment could contain
 750  *                 ASCII text that encoded and explained the cause of the
 751  *                 RST.  No standard has yet been established for such
 752  *                 data.
 753  *
 754  */
 755
 756 static void
 757 print_tcp_rst_data(register const u_char *sp, u_int length)
 758 {
 759         int c;
 760
 761         if (TTEST2(*sp, length))
 762                 printf(" [RST");
 763         else
 764                 printf(" [!RST");
 765         if (length > MAX_RST_DATA_LEN) {
 766                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 767                 putchar('+');                   /* indicate we truncate */
 768         }
 769         putchar(' ');
 770         while (length-- && sp <= snapend) {
 771                 c = *sp++;
 772                 safeputchar(c);
 773         }
 774         putchar(']');
 775 }
 776
 777 #ifdef HAVE_LIBCRYPTO
 778 static int
 779 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 780                      const u_char *data, int length, const u_char *rcvsig)
 781 {
 782         struct tcphdr tp1;
 783         u_char sig[TCP_SIGLEN];
 784         char zero_proto = 0;
 785         MD5_CTX ctx;
 786         u_int16_t savecsum, tlen;
 787 #ifdef INET6
 788         struct ip6_hdr *ip6;
 789         u_int32_t len32;
 790         u_int8_t nxt;
 791 #endif
 792
 793         if (data + length > snapend) {
 794                 printf("snaplen too short, ");
 795                 return (CANT_CHECK_SIGNATURE);
 796         }
 797
 798         tp1 = *tp;
 799
 800         if (sigsecret == NULL) {
 801                 printf("shared secret not supplied with -M, ");
 802                 return (CANT_CHECK_SIGNATURE);
 803         }
 804
 805         MD5_Init(&ctx);
 806         /*
 807          * Step 1: Update MD5 hash with IP pseudo-header.
 808          */
 809         if (IP_V(ip) == 4) {
 810                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 811                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 812                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 813                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 814                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 815                 tlen = htons(tlen);
 816                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 817 #ifdef INET6
 818         } else if (IP_V(ip) == 6) {
 819                 ip6 = (struct ip6_hdr *)ip;
 820                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 821                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 822                 len32 = htonl(EXTRACT_16BITS(&ip6->ip6_plen));
 823                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 824                 nxt = 0;
 825                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 826                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 827                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 828                 nxt = IPPROTO_TCP;
 829                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 830 #endif
 831         } else {
 832 #ifdef INET6
 833                 printf("IP version not 4 or 6, ");
 834 #else
 835                 printf("IP version not 4, ");
 836 #endif
 837                 return (CANT_CHECK_SIGNATURE);
 838         }
 839
 840         /*
 841          * Step 2: Update MD5 hash with TCP header, excluding options.
 842          * The TCP checksum must be set to zero.
 843          */
 844         savecsum = tp1.th_sum;
 845         tp1.th_sum = 0;
 846         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 847         tp1.th_sum = savecsum;
 848         /*
 849          * Step 3: Update MD5 hash with TCP segment data, if present.
 850          */
 851         if (length > 0)
 852                 MD5_Update(&ctx, data, length);
 853         /*
 854          * Step 4: Update MD5 hash with shared secret.
 855          */
 856         MD5_Update(&ctx, sigsecret, strlen(sigsecret));
 857         MD5_Final(sig, &ctx);
 858
 859         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 860                 return (SIGNATURE_VALID);
 861         else
 862                 return (SIGNATURE_INVALID);
 863 }
 864 #endif /* HAVE_LIBCRYPTO */
 865
 866 /*
 867  * Local Variables:
 868  * c-style: whitesmith
 869  * c-basic-offset: 8
 870  * End:
 871  */