contrib/tcpdump/print-tcp.c

   1 /*      $NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky Exp $     */
   2
   3 /*
   4  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Copyright (c) 1999-2004 The tcpdump.org project
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that: (1) source code distributions
  11  * retain the above copyright notice and this paragraph in its entirety, (2)
  12  * distributions including binary code include the above copyright notice and
  13  * this paragraph in its entirety in the documentation or other materials
  14  * provided with the distribution, and (3) all advertising materials mentioning
  15  * features or use of this software display the following acknowledgement:
  16  * ``This product includes software developed by the University of California,
  17  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  18  * the University nor the names of its contributors may be used to endorse
  19  * or promote products derived from this software without specific prior
  20  * written permission.
  21  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  22  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  23  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  24  */
  25
  26 #ifndef lint
  27 static const char rcsid[] _U_ =
  28 "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.130.2.3 2007-12-22 03:08:45 guy 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         { TCPOPT_UTO, "uto" },
 128         { 0, NULL }
 129 };
 130
 131 static int tcp_cksum(register const struct ip *ip,
 132                      register const struct tcphdr *tp,
 133                      register u_int len)
 134 {
 135         union phu {
 136                 struct phdr {
 137                         u_int32_t src;
 138                         u_int32_t dst;
 139                         u_char mbz;
 140                         u_char proto;
 141                         u_int16_t len;
 142                 } ph;
 143                 u_int16_t pa[6];
 144         } phu;
 145         const u_int16_t *sp;
 146
 147         /* pseudo-header.. */
 148         phu.ph.len = htons((u_int16_t)len);
 149         phu.ph.mbz = 0;
 150         phu.ph.proto = IPPROTO_TCP;
 151         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 152         if (IP_HL(ip) == 5)
 153                 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 154         else
 155                 phu.ph.dst = ip_finddst(ip);
 156
 157         sp = &phu.pa[0];
 158         return in_cksum((u_short *)tp, len,
 159                         sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
 160 }
 161
 162 #ifdef INET6
 163 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 164                       u_int len)
 165 {
 166         size_t i;
 167         u_int32_t sum = 0;
 168         union {
 169                 struct {
 170                         struct in6_addr ph_src;
 171                         struct in6_addr ph_dst;
 172                         u_int32_t       ph_len;
 173                         u_int8_t        ph_zero[3];
 174                         u_int8_t        ph_nxt;
 175                 } ph;
 176                 u_int16_t pa[20];
 177         } phu;
 178
 179         /* pseudo-header */
 180         memset(&phu, 0, sizeof(phu));
 181         phu.ph.ph_src = ip6->ip6_src;
 182         phu.ph.ph_dst = ip6->ip6_dst;
 183         phu.ph.ph_len = htonl(len);
 184         phu.ph.ph_nxt = IPPROTO_TCP;
 185
 186         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 187                 sum += phu.pa[i];
 188
 189         return in_cksum((u_short *)tp, len, sum);
 190 }
 191 #endif
 192
 193 void
 194 tcp_print(register const u_char *bp, register u_int length,
 195           register const u_char *bp2, int fragmented)
 196 {
 197         register const struct tcphdr *tp;
 198         register const struct ip *ip;
 199         register u_char flags;
 200         register u_int hlen;
 201         register char ch;
 202         u_int16_t sport, dport, win, urp;
 203         u_int32_t seq, ack, thseq, thack;
 204         int threv;
 205 #ifdef INET6
 206         register const struct ip6_hdr *ip6;
 207 #endif
 208
 209         tp = (struct tcphdr *)bp;
 210         ip = (struct ip *)bp2;
 211 #ifdef INET6
 212         if (IP_V(ip) == 6)
 213                 ip6 = (struct ip6_hdr *)bp2;
 214         else
 215                 ip6 = NULL;
 216 #endif /*INET6*/
 217         ch = '\0';
 218         if (!TTEST(tp->th_dport)) {
 219                 (void)printf("%s > %s: [|tcp]",
 220                              ipaddr_string(&ip->ip_src),
 221                              ipaddr_string(&ip->ip_dst));
 222                 return;
 223         }
 224
 225         sport = EXTRACT_16BITS(&tp->th_sport);
 226         dport = EXTRACT_16BITS(&tp->th_dport);
 227
 228         hlen = TH_OFF(tp) * 4;
 229
 230         /*
 231          * If data present, header length valid, and NFS port used,
 232          * assume NFS.
 233          * Pass offset of data plus 4 bytes for RPC TCP msg length
 234          * to NFS print routines.
 235          */
 236         if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
 237             (length - hlen) >= 4) {
 238                 u_char *fraglenp;
 239                 u_int32_t fraglen;
 240                 register struct sunrpc_msg *rp;
 241                 enum sunrpc_msg_type direction;
 242
 243                 fraglenp = (u_char *)tp + hlen;
 244                 if (TTEST2(*fraglenp, 4)) {
 245                         fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
 246                         if (fraglen > (length - hlen) - 4)
 247                                 fraglen = (length - hlen) - 4;
 248                         rp = (struct sunrpc_msg *)(fraglenp + 4);
 249                         if (TTEST(rp->rm_direction)) {
 250                                 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
 251                                 if (dport == NFS_PORT &&
 252                                     direction == SUNRPC_CALL) {
 253                                         nfsreq_print((u_char *)rp, fraglen,
 254                                             (u_char *)ip);
 255                                         return;
 256                                 }
 257                                 if (sport == NFS_PORT &&
 258                                     direction == SUNRPC_REPLY) {
 259                                         nfsreply_print((u_char *)rp, fraglen,
 260                                             (u_char *)ip);
 261                                         return;
 262                                 }
 263                         }
 264                 }
 265         }
 266 #ifdef INET6
 267         if (ip6) {
 268                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 269                         (void)printf("%s.%s > %s.%s: ",
 270                                      ip6addr_string(&ip6->ip6_src),
 271                                      tcpport_string(sport),
 272                                      ip6addr_string(&ip6->ip6_dst),
 273                                      tcpport_string(dport));
 274                 } else {
 275                         (void)printf("%s > %s: ",
 276                                      tcpport_string(sport), tcpport_string(dport));
 277                 }
 278         } else
 279 #endif /*INET6*/
 280         {
 281                 if (ip->ip_p == IPPROTO_TCP) {
 282                         (void)printf("%s.%s > %s.%s: ",
 283                                      ipaddr_string(&ip->ip_src),
 284                                      tcpport_string(sport),
 285                                      ipaddr_string(&ip->ip_dst),
 286                                      tcpport_string(dport));
 287                 } else {
 288                         (void)printf("%s > %s: ",
 289                                      tcpport_string(sport), tcpport_string(dport));
 290                 }
 291         }
 292
 293         if (hlen < sizeof(*tp)) {
 294                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 295                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 296                 return;
 297         }
 298
 299         TCHECK(*tp);
 300
 301         seq = EXTRACT_32BITS(&tp->th_seq);
 302         ack = EXTRACT_32BITS(&tp->th_ack);
 303         win = EXTRACT_16BITS(&tp->th_win);
 304         urp = EXTRACT_16BITS(&tp->th_urp);
 305
 306         if (qflag) {
 307                 (void)printf("tcp %d", length - hlen);
 308                 if (hlen > length) {
 309                         (void)printf(" [bad hdr length %u - too long, > %u]",
 310                                      hlen, length);
 311                 }
 312                 return;
 313         }
 314
 315         flags = tp->th_flags;
 316         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 317
 318         if (!Sflag && (flags & TH_ACK)) {
 319                 register struct tcp_seq_hash *th;
 320                 const void *src, *dst;
 321                 register int rev;
 322                 struct tha tha;
 323                 /*
 324                  * Find (or record) the initial sequence numbers for
 325                  * this conversation.  (we pick an arbitrary
 326                  * collating order so there's only one entry for
 327                  * both directions).
 328                  */
 329 #ifdef INET6
 330                 memset(&tha, 0, sizeof(tha));
 331                 rev = 0;
 332                 if (ip6) {
 333                         src = &ip6->ip6_src;
 334                         dst = &ip6->ip6_dst;
 335                         if (sport > dport)
 336                                 rev = 1;
 337                         else if (sport == dport) {
 338                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 339                                         rev = 1;
 340                         }
 341                         if (rev) {
 342                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 343                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 344                                 tha.port = dport << 16 | sport;
 345                         } else {
 346                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 347                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 348                                 tha.port = sport << 16 | dport;
 349                         }
 350                 } else {
 351                         src = &ip->ip_src;
 352                         dst = &ip->ip_dst;
 353                         if (sport > dport)
 354                                 rev = 1;
 355                         else if (sport == dport) {
 356                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 357                                         rev = 1;
 358                         }
 359                         if (rev) {
 360                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 361                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 362                                 tha.port = dport << 16 | sport;
 363                         } else {
 364                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 365                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 366                                 tha.port = sport << 16 | dport;
 367                         }
 368                 }
 369 #else
 370                 rev = 0;
 371                 src = &ip->ip_src;
 372                 dst = &ip->ip_dst;
 373                 if (sport > dport)
 374                         rev = 1;
 375                 else if (sport == dport) {
 376                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 377                                 rev = 1;
 378                 }
 379                 if (rev) {
 380                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 381                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 382                         tha.port = dport << 16 | sport;
 383                 } else {
 384                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 385                         memcpy(&tha.src, src, sizeof ip->ip_src);
 386                         tha.port = sport << 16 | dport;
 387                 }
 388 #endif
 389
 390                 threv = rev;
 391                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 392                      th->nxt; th = th->nxt)
 393                         if (memcmp((char *)&tha, (char *)&th->addr,
 394                                    sizeof(th->addr)) == 0)
 395                                 break;
 396
 397                 if (!th->nxt || (flags & TH_SYN)) {
 398                         /* didn't find it or new conversation */
 399                         if (th->nxt == NULL) {
 400                                 th->nxt = (struct tcp_seq_hash *)
 401                                         calloc(1, sizeof(*th));
 402                                 if (th->nxt == NULL)
 403                                         error("tcp_print: calloc");
 404                         }
 405                         th->addr = tha;
 406                         if (rev)
 407                                 th->ack = seq, th->seq = ack - 1;
 408                         else
 409                                 th->seq = seq, th->ack = ack - 1;
 410                 } else {
 411                         if (rev)
 412                                 seq -= th->ack, ack -= th->seq;
 413                         else
 414                                 seq -= th->seq, ack -= th->ack;
 415                 }
 416
 417                 thseq = th->seq;
 418                 thack = th->ack;
 419         } else {
 420                 /*fool gcc*/
 421                 thseq = thack = threv = 0;
 422         }
 423         if (hlen > length) {
 424                 (void)printf(" [bad hdr length %u - too long, > %u]",
 425                              hlen, length);
 426                 return;
 427         }
 428
 429         if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 430                 u_int16_t sum, tcp_sum;
 431                 if (TTEST2(tp->th_sport, length)) {
 432                         sum = tcp_cksum(ip, tp, length);
 433
 434                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 435                         if (sum != 0) {
 436                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 437                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 438                         } else
 439                                 (void)printf(" (correct)");
 440                 }
 441         }
 442 #ifdef INET6
 443         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 444                 u_int16_t sum,tcp_sum;
 445                 if (TTEST2(tp->th_sport, length)) {
 446                         sum = tcp6_cksum(ip6, tp, length);
 447                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 448                         if (sum != 0) {
 449                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 450                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 451                         } else
 452                                 (void)printf(" (correct)");
 453
 454                 }
 455         }
 456 #endif
 457
 458         length -= hlen;
 459         if (vflag > 1 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 460                 (void)printf(", seq %u", seq);
 461
 462                 if (length > 0) {
 463                         (void)printf(":%u", seq + length);
 464                 }
 465         }
 466
 467         if (flags & TH_ACK) {
 468                 (void)printf(", ack %u", ack);
 469         }
 470
 471         (void)printf(", win %d", win);
 472
 473         if (flags & TH_URG)
 474                 (void)printf(", urg %d", urp);
 475         /*
 476          * Handle any options.
 477          */
 478         if (hlen > sizeof(*tp)) {
 479                 register const u_char *cp;
 480                 register u_int i, opt, datalen;
 481                 register u_int len;
 482
 483                 hlen -= sizeof(*tp);
 484                 cp = (const u_char *)tp + sizeof(*tp);
 485                 printf(", options [");
 486                 while (hlen > 0) {
 487                         if (ch != '\0')
 488                                 putchar(ch);
 489                         TCHECK(*cp);
 490                         opt = *cp++;
 491                         if (ZEROLENOPT(opt))
 492                                 len = 1;
 493                         else {
 494                                 TCHECK(*cp);
 495                                 len = *cp++;    /* total including type, len */
 496                                 if (len < 2 || len > hlen)
 497                                         goto bad;
 498                                 --hlen;         /* account for length byte */
 499                         }
 500                         --hlen;                 /* account for type byte */
 501                         datalen = 0;
 502
 503 /* Bail if "l" bytes of data are not left or were not captured  */
 504 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 505
 506
 507                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 508
 509                         switch (opt) {
 510
 511                         case TCPOPT_MAXSEG:
 512                                 datalen = 2;
 513                                 LENCHECK(datalen);
 514                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 515                                 break;
 516
 517                         case TCPOPT_WSCALE:
 518                                 datalen = 1;
 519                                 LENCHECK(datalen);
 520                                 (void)printf(" %u", *cp);
 521                                 break;
 522
 523                         case TCPOPT_SACK:
 524                                 datalen = len - 2;
 525                                 if (datalen % 8 != 0) {
 526                                         (void)printf("malformed sack");
 527                                 } else {
 528                                         u_int32_t s, e;
 529
 530                                         (void)printf(" %d ", datalen / 8);
 531                                         for (i = 0; i < datalen; i += 8) {
 532                                                 LENCHECK(i + 4);
 533                                                 s = EXTRACT_32BITS(cp + i);
 534                                                 LENCHECK(i + 8);
 535                                                 e = EXTRACT_32BITS(cp + i + 4);
 536                                                 if (threv) {
 537                                                         s -= thseq;
 538                                                         e -= thseq;
 539                                                 } else {
 540                                                         s -= thack;
 541                                                         e -= thack;
 542                                                 }
 543                                                 (void)printf("{%u:%u}", s, e);
 544                                         }
 545                                 }
 546                                 break;
 547
 548                         case TCPOPT_CC:
 549                         case TCPOPT_CCNEW:
 550                         case TCPOPT_CCECHO:
 551                         case TCPOPT_ECHO:
 552                         case TCPOPT_ECHOREPLY:
 553
 554                                 /*
 555                                  * those options share their semantics.
 556                                  * fall through
 557                                  */
 558                                 datalen = 4;
 559                                 LENCHECK(datalen);
 560                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 561                                 break;
 562
 563                         case TCPOPT_TIMESTAMP:
 564                                 datalen = 8;
 565                                 LENCHECK(datalen);
 566                                 (void)printf(" val %u ecr %u",
 567                                              EXTRACT_32BITS(cp),
 568                                              EXTRACT_32BITS(cp + 4));
 569                                 break;
 570
 571                         case TCPOPT_SIGNATURE:
 572                                 datalen = TCP_SIGLEN;
 573                                 LENCHECK(datalen);
 574 #ifdef HAVE_LIBCRYPTO
 575                                 switch (tcp_verify_signature(ip, tp,
 576                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 577
 578                                 case SIGNATURE_VALID:
 579                                         (void)printf("valid");
 580                                         break;
 581
 582                                 case SIGNATURE_INVALID:
 583                                         (void)printf("invalid");
 584                                         break;
 585
 586                                 case CANT_CHECK_SIGNATURE:
 587                                         (void)printf("can't check - ");
 588                                         for (i = 0; i < TCP_SIGLEN; ++i)
 589                                                 (void)printf("%02x", cp[i]);
 590                                         break;
 591                                 }
 592 #else
 593                                 for (i = 0; i < TCP_SIGLEN; ++i)
 594                                         (void)printf("%02x", cp[i]);
 595 #endif
 596                                 break;
 597
 598                         case TCPOPT_AUTH:
 599                                 (void)printf("keyid %d", *cp++);
 600                                 datalen = len - 3;
 601                                 for (i = 0; i < datalen; ++i) {
 602                                         LENCHECK(i);
 603                                         (void)printf("%02x", cp[i]);
 604                                 }
 605                                 break;
 606
 607
 608                         case TCPOPT_EOL:
 609                         case TCPOPT_NOP:
 610                         case TCPOPT_SACKOK:
 611                                 /*
 612                                  * Nothing interesting.
 613                                  * fall through
 614                                  */
 615                                 break;
 616
 617                         case TCPOPT_UTO:
 618                                 datalen = 2;
 619                                 LENCHECK(datalen);
 620                                 uint utoval = EXTRACT_16BITS(cp);
 621                                 if (utoval & 0x0001)
 622                                         utoval = (utoval >> 1) * 60;
 623                                 else
 624                                         utoval >>= 1;
 625                                 (void)printf(" %u", utoval);
 626                                 break;
 627
 628                         default:
 629                                 datalen = len - 2;
 630                                 for (i = 0; i < datalen; ++i) {
 631                                         LENCHECK(i);
 632                                         (void)printf("%02x", cp[i]);
 633                                 }
 634                                 break;
 635                         }
 636
 637                         /* Account for data printed */
 638                         cp += datalen;
 639                         hlen -= datalen;
 640
 641                         /* Check specification against observed length */
 642                         ++datalen;                      /* option octet */
 643                         if (!ZEROLENOPT(opt))
 644                                 ++datalen;              /* size octet */
 645                         if (datalen != len)
 646                                 (void)printf("[len %d]", len);
 647                         ch = ',';
 648                         if (opt == TCPOPT_EOL)
 649                                 break;
 650                 }
 651                 putchar(']');
 652         }
 653
 654         /*
 655          * Print length field before crawling down the stack.
 656          */
 657         printf(", length %u", length);
 658
 659         if (length <= 0)
 660                 return;
 661
 662         /*
 663          * Decode payload if necessary.
 664          */
 665         bp += TH_OFF(tp) * 4;
 666         if ((flags & TH_RST) && vflag) {
 667                 print_tcp_rst_data(bp, length);
 668                 return;
 669         }
 670
 671         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 672                 if (!qflag && vflag)
 673                         telnet_print(bp, length);
 674         } else if (sport == BGP_PORT || dport == BGP_PORT)
 675                 bgp_print(bp, length);
 676         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 677                 pptp_print(bp);
 678 #ifdef TCPDUMP_DO_SMB
 679         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 680                 nbt_tcp_print(bp, length);
 681         else if (sport == SMB_PORT || dport == SMB_PORT)
 682                 smb_tcp_print(bp, length);
 683 #endif
 684         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 685                 beep_print(bp, length);
 686         else if (length > 2 &&
 687                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 688                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 689                 /*
 690                  * TCP DNS query has 2byte length at the head.
 691                  * XXX packet could be unaligned, it can go strange
 692                  */
 693                 ns_print(bp + 2, length - 2, 0);
 694         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 695                 msdp_print(bp, length);
 696         }
 697         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 698                 ldp_print(bp, length);
 699         }
 700
 701         return;
 702  bad:
 703         fputs("[bad opt]", stdout);
 704         if (ch != '\0')
 705                 putchar('>');
 706         return;
 707  trunc:
 708         fputs("[|tcp]", stdout);
 709         if (ch != '\0')
 710                 putchar('>');
 711 }
 712
 713 /*
 714  * RFC1122 says the following on data in RST segments:
 715  *
 716  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 717  *
 718  *            A TCP SHOULD allow a received RST segment to include data.
 719  *
 720  *            DISCUSSION
 721  *                 It has been suggested that a RST segment could contain
 722  *                 ASCII text that encoded and explained the cause of the
 723  *                 RST.  No standard has yet been established for such
 724  *                 data.
 725  *
 726  */
 727
 728 static void
 729 print_tcp_rst_data(register const u_char *sp, u_int length)
 730 {
 731         int c;
 732
 733         if (TTEST2(*sp, length))
 734                 printf(" [RST");
 735         else
 736                 printf(" [!RST");
 737         if (length > MAX_RST_DATA_LEN) {
 738                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 739                 putchar('+');                   /* indicate we truncate */
 740         }
 741         putchar(' ');
 742         while (length-- && sp <= snapend) {
 743                 c = *sp++;
 744                 safeputchar(c);
 745         }
 746         putchar(']');
 747 }
 748
 749 #ifdef HAVE_LIBCRYPTO
 750 static int
 751 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 752                      const u_char *data, int length, const u_char *rcvsig)
 753 {
 754         struct tcphdr tp1;
 755         u_char sig[TCP_SIGLEN];
 756         char zero_proto = 0;
 757         MD5_CTX ctx;
 758         u_int16_t savecsum, tlen;
 759 #ifdef INET6
 760         struct ip6_hdr *ip6;
 761         u_int32_t len32;
 762         u_int8_t nxt;
 763 #endif
 764
 765         tp1 = *tp;
 766
 767         if (tcpmd5secret == NULL)
 768                 return (CANT_CHECK_SIGNATURE);
 769
 770         MD5_Init(&ctx);
 771         /*
 772          * Step 1: Update MD5 hash with IP pseudo-header.
 773          */
 774         if (IP_V(ip) == 4) {
 775                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 776                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 777                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 778                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 779                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 780                 tlen = htons(tlen);
 781                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 782 #ifdef INET6
 783         } else if (IP_V(ip) == 6) {
 784                 ip6 = (struct ip6_hdr *)ip;
 785                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 786                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 787                 len32 = htonl(ntohs(ip6->ip6_plen));
 788                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 789                 nxt = 0;
 790                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 791                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 792                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 793                 nxt = IPPROTO_TCP;
 794                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 795 #endif
 796         } else
 797                 return (CANT_CHECK_SIGNATURE);
 798
 799         /*
 800          * Step 2: Update MD5 hash with TCP header, excluding options.
 801          * The TCP checksum must be set to zero.
 802          */
 803         savecsum = tp1.th_sum;
 804         tp1.th_sum = 0;
 805         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 806         tp1.th_sum = savecsum;
 807         /*
 808          * Step 3: Update MD5 hash with TCP segment data, if present.
 809          */
 810         if (length > 0)
 811                 MD5_Update(&ctx, data, length);
 812         /*
 813          * Step 4: Update MD5 hash with shared secret.
 814          */
 815         MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
 816         MD5_Final(sig, &ctx);
 817
 818         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 819                 return (SIGNATURE_VALID);
 820         else
 821                 return (SIGNATURE_INVALID);
 822 }
 823 #endif /* HAVE_LIBCRYPTO */
 824
 825 /*
 826  * Local Variables:
 827  * c-style: whitesmith
 828  * c-basic-offset: 8
 829  * End:
 830  */