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

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Copyright (c) 1999-2004 The tcpdump.org project
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that: (1) source code distributions
   9  * retain the above copyright notice and this paragraph in its entirety, (2)
  10  * distributions including binary code include the above copyright notice and
  11  * this paragraph in its entirety in the documentation or other materials
  12  * provided with the distribution, and (3) all advertising materials mentioning
  13  * features or use of this software display the following acknowledgement:
  14  * ``This product includes software developed by the University of California,
  15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  16  * the University nor the names of its contributors may be used to endorse
  17  * or promote products derived from this software without specific prior
  18  * written permission.
  19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  22  */
  23
  24 #ifndef lint
  25 static const char rcsid[] _U_ =
  26 "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.129 2007-04-03 20:02:56 guy Exp $ (LBL)";
  27 #endif
  28
  29 #ifdef HAVE_CONFIG_H
  30 #include "config.h"
  31 #endif
  32
  33 #include <tcpdump-stdinc.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #include "interface.h"
  40 #include "addrtoname.h"
  41 #include "extract.h"
  42
  43 #include "tcp.h"
  44
  45 #include "ip.h"
  46 #ifdef INET6
  47 #include "ip6.h"
  48 #endif
  49 #include "ipproto.h"
  50 #include "rpc_auth.h"
  51 #include "rpc_msg.h"
  52
  53 #include "nameser.h"
  54
  55 #ifdef HAVE_LIBCRYPTO
  56 #include <openssl/md5.h>
  57
  58 #define SIGNATURE_VALID         0
  59 #define SIGNATURE_INVALID       1
  60 #define CANT_CHECK_SIGNATURE    2
  61
  62 static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
  63                                 const u_char *data, int length, const u_char *rcvsig);
  64 #endif
  65
  66 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  67
  68 #define MAX_RST_DATA_LEN        30
  69
  70
  71 struct tha {
  72 #ifndef INET6
  73         struct in_addr src;
  74         struct in_addr dst;
  75 #else
  76         struct in6_addr src;
  77         struct in6_addr dst;
  78 #endif /*INET6*/
  79         u_int port;
  80 };
  81
  82 struct tcp_seq_hash {
  83         struct tcp_seq_hash *nxt;
  84         struct tha addr;
  85         tcp_seq seq;
  86         tcp_seq ack;
  87 };
  88
  89 #define TSEQ_HASHSIZE 919
  90
  91 /* These tcp optinos do not have the size octet */
  92 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
  93
  94 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
  95
  96 struct tok tcp_flag_values[] = {
  97         { TH_FIN, "F" },
  98         { TH_SYN, "S" },
  99         { TH_RST, "R" },
 100         { TH_PUSH, "P" },
 101         { TH_ACK, "." },
 102         { TH_URG, "U" },
 103         { TH_ECNECHO, "E" },
 104         { TH_CWR, "W" },
 105         { 0, NULL }
 106 };
 107
 108 struct tok tcp_option_values[] = {
 109         { TCPOPT_EOL, "eol" },
 110         { TCPOPT_NOP, "nop" },
 111         { TCPOPT_MAXSEG, "mss" },
 112         { TCPOPT_WSCALE, "wscale" },
 113         { TCPOPT_SACKOK, "sackOK" },
 114         { TCPOPT_SACK, "sack" },
 115         { TCPOPT_ECHO, "echo" },
 116         { TCPOPT_ECHOREPLY, "echoreply" },
 117         { TCPOPT_TIMESTAMP, "TS" },
 118         { TCPOPT_CC, "cc" },
 119         { TCPOPT_CCNEW, "ccnew" },
 120         { TCPOPT_CCECHO, "" },
 121         { TCPOPT_SIGNATURE, "md5" },
 122         { TCPOPT_AUTH, "enhanced auth" },
 123         { 0, NULL }
 124 };
 125
 126 static int tcp_cksum(register const struct ip *ip,
 127                      register const struct tcphdr *tp,
 128                      register u_int len)
 129 {
 130         union phu {
 131                 struct phdr {
 132                         u_int32_t src;
 133                         u_int32_t dst;
 134                         u_char mbz;
 135                         u_char proto;
 136                         u_int16_t len;
 137                 } ph;
 138                 u_int16_t pa[6];
 139         } phu;
 140         const u_int16_t *sp;
 141
 142         /* pseudo-header.. */
 143         phu.ph.len = htons((u_int16_t)len);
 144         phu.ph.mbz = 0;
 145         phu.ph.proto = IPPROTO_TCP;
 146         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 147         if (IP_HL(ip) == 5)
 148                 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 149         else
 150                 phu.ph.dst = ip_finddst(ip);
 151
 152         sp = &phu.pa[0];
 153         return in_cksum((u_short *)tp, len,
 154                         sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
 155 }
 156
 157 #ifdef INET6
 158 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 159                       u_int len)
 160 {
 161         size_t i;
 162         u_int32_t sum = 0;
 163         union {
 164                 struct {
 165                         struct in6_addr ph_src;
 166                         struct in6_addr ph_dst;
 167                         u_int32_t       ph_len;
 168                         u_int8_t        ph_zero[3];
 169                         u_int8_t        ph_nxt;
 170                 } ph;
 171                 u_int16_t pa[20];
 172         } phu;
 173
 174         /* pseudo-header */
 175         memset(&phu, 0, sizeof(phu));
 176         phu.ph.ph_src = ip6->ip6_src;
 177         phu.ph.ph_dst = ip6->ip6_dst;
 178         phu.ph.ph_len = htonl(len);
 179         phu.ph.ph_nxt = IPPROTO_TCP;
 180
 181         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 182                 sum += phu.pa[i];
 183
 184         return in_cksum((u_short *)tp, len, sum);
 185 }
 186 #endif
 187
 188 void
 189 tcp_print(register const u_char *bp, register u_int length,
 190           register const u_char *bp2, int fragmented)
 191 {
 192         register const struct tcphdr *tp;
 193         register const struct ip *ip;
 194         register u_char flags;
 195         register u_int hlen;
 196         register char ch;
 197         u_int16_t sport, dport, win, urp;
 198         u_int32_t seq, ack, thseq, thack;
 199         int threv;
 200 #ifdef INET6
 201         register const struct ip6_hdr *ip6;
 202 #endif
 203
 204         tp = (struct tcphdr *)bp;
 205         ip = (struct ip *)bp2;
 206 #ifdef INET6
 207         if (IP_V(ip) == 6)
 208                 ip6 = (struct ip6_hdr *)bp2;
 209         else
 210                 ip6 = NULL;
 211 #endif /*INET6*/
 212         ch = '\0';
 213         if (!TTEST(tp->th_dport)) {
 214                 (void)printf("%s > %s: [|tcp]",
 215                              ipaddr_string(&ip->ip_src),
 216                              ipaddr_string(&ip->ip_dst));
 217                 return;
 218         }
 219
 220         sport = EXTRACT_16BITS(&tp->th_sport);
 221         dport = EXTRACT_16BITS(&tp->th_dport);
 222
 223         hlen = TH_OFF(tp) * 4;
 224
 225         /*
 226          * If data present, header length valid, and NFS port used,
 227          * assume NFS.
 228          * Pass offset of data plus 4 bytes for RPC TCP msg length
 229          * to NFS print routines.
 230          */
 231         if (!qflag && hlen >= sizeof(*tp) && hlen <= length) {
 232                 if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg) <= snapend &&
 233                     dport == NFS_PORT) {
 234                         nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
 235                                      (u_char *)ip);
 236                         return;
 237                 } else if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg)
 238                            <= snapend &&
 239                            sport == NFS_PORT) {
 240                         nfsreply_print((u_char *)tp + hlen + 4, length - hlen,
 241                                        (u_char *)ip);
 242                         return;
 243                 }
 244         }
 245 #ifdef INET6
 246         if (ip6) {
 247                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 248                         (void)printf("%s.%s > %s.%s: ",
 249                                      ip6addr_string(&ip6->ip6_src),
 250                                      tcpport_string(sport),
 251                                      ip6addr_string(&ip6->ip6_dst),
 252                                      tcpport_string(dport));
 253                 } else {
 254                         (void)printf("%s > %s: ",
 255                                      tcpport_string(sport), tcpport_string(dport));
 256                 }
 257         } else
 258 #endif /*INET6*/
 259         {
 260                 if (ip->ip_p == IPPROTO_TCP) {
 261                         (void)printf("%s.%s > %s.%s: ",
 262                                      ipaddr_string(&ip->ip_src),
 263                                      tcpport_string(sport),
 264                                      ipaddr_string(&ip->ip_dst),
 265                                      tcpport_string(dport));
 266                 } else {
 267                         (void)printf("%s > %s: ",
 268                                      tcpport_string(sport), tcpport_string(dport));
 269                 }
 270         }
 271
 272         if (hlen < sizeof(*tp)) {
 273                 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
 274                              length - hlen, hlen, (unsigned long)sizeof(*tp));
 275                 return;
 276         }
 277
 278         TCHECK(*tp);
 279
 280         seq = EXTRACT_32BITS(&tp->th_seq);
 281         ack = EXTRACT_32BITS(&tp->th_ack);
 282         win = EXTRACT_16BITS(&tp->th_win);
 283         urp = EXTRACT_16BITS(&tp->th_urp);
 284
 285         if (qflag) {
 286                 (void)printf("tcp %d", length - hlen);
 287                 if (hlen > length) {
 288                         (void)printf(" [bad hdr length %u - too long, > %u]",
 289                                      hlen, length);
 290                 }
 291                 return;
 292         }
 293
 294         flags = tp->th_flags;
 295         printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 296
 297         if (!Sflag && (flags & TH_ACK)) {
 298                 register struct tcp_seq_hash *th;
 299                 const void *src, *dst;
 300                 register int rev;
 301                 struct tha tha;
 302                 /*
 303                  * Find (or record) the initial sequence numbers for
 304                  * this conversation.  (we pick an arbitrary
 305                  * collating order so there's only one entry for
 306                  * both directions).
 307                  */
 308 #ifdef INET6
 309                 memset(&tha, 0, sizeof(tha));
 310                 rev = 0;
 311                 if (ip6) {
 312                         src = &ip6->ip6_src;
 313                         dst = &ip6->ip6_dst;
 314                         if (sport > dport)
 315                                 rev = 1;
 316                         else if (sport == dport) {
 317                                 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
 318                                         rev = 1;
 319                         }
 320                         if (rev) {
 321                                 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
 322                                 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
 323                                 tha.port = dport << 16 | sport;
 324                         } else {
 325                                 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
 326                                 memcpy(&tha.src, src, sizeof ip6->ip6_src);
 327                                 tha.port = sport << 16 | dport;
 328                         }
 329                 } else {
 330                         src = &ip->ip_src;
 331                         dst = &ip->ip_dst;
 332                         if (sport > dport)
 333                                 rev = 1;
 334                         else if (sport == dport) {
 335                                 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 336                                         rev = 1;
 337                         }
 338                         if (rev) {
 339                                 memcpy(&tha.src, dst, sizeof ip->ip_dst);
 340                                 memcpy(&tha.dst, src, sizeof ip->ip_src);
 341                                 tha.port = dport << 16 | sport;
 342                         } else {
 343                                 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 344                                 memcpy(&tha.src, src, sizeof ip->ip_src);
 345                                 tha.port = sport << 16 | dport;
 346                         }
 347                 }
 348 #else
 349                 rev = 0;
 350                 src = &ip->ip_src;
 351                 dst = &ip->ip_dst;
 352                 if (sport > dport)
 353                         rev = 1;
 354                 else if (sport == dport) {
 355                         if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
 356                                 rev = 1;
 357                 }
 358                 if (rev) {
 359                         memcpy(&tha.src, dst, sizeof ip->ip_dst);
 360                         memcpy(&tha.dst, src, sizeof ip->ip_src);
 361                         tha.port = dport << 16 | sport;
 362                 } else {
 363                         memcpy(&tha.dst, dst, sizeof ip->ip_dst);
 364                         memcpy(&tha.src, src, sizeof ip->ip_src);
 365                         tha.port = sport << 16 | dport;
 366                 }
 367 #endif
 368
 369                 threv = rev;
 370                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 371                      th->nxt; th = th->nxt)
 372                         if (memcmp((char *)&tha, (char *)&th->addr,
 373                                    sizeof(th->addr)) == 0)
 374                                 break;
 375
 376                 if (!th->nxt || (flags & TH_SYN)) {
 377                         /* didn't find it or new conversation */
 378                         if (th->nxt == NULL) {
 379                                 th->nxt = (struct tcp_seq_hash *)
 380                                         calloc(1, sizeof(*th));
 381                                 if (th->nxt == NULL)
 382                                         error("tcp_print: calloc");
 383                         }
 384                         th->addr = tha;
 385                         if (rev)
 386                                 th->ack = seq, th->seq = ack - 1;
 387                         else
 388                                 th->seq = seq, th->ack = ack - 1;
 389                 } else {
 390                         if (rev)
 391                                 seq -= th->ack, ack -= th->seq;
 392                         else
 393                                 seq -= th->seq, ack -= th->ack;
 394                 }
 395
 396                 thseq = th->seq;
 397                 thack = th->ack;
 398         } else {
 399                 /*fool gcc*/
 400                 thseq = thack = threv = 0;
 401         }
 402         if (hlen > length) {
 403                 (void)printf(" [bad hdr length %u - too long, > %u]",
 404                              hlen, length);
 405                 return;
 406         }
 407
 408         if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 409                 u_int16_t sum, tcp_sum;
 410                 if (TTEST2(tp->th_sport, length)) {
 411                         sum = tcp_cksum(ip, tp, length);
 412
 413                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 414                         if (sum != 0) {
 415                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 416                                 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 417                         } else
 418                                 (void)printf(" (correct)");
 419                 }
 420         }
 421 #ifdef INET6
 422         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 423                 u_int16_t sum,tcp_sum;
 424                 if (TTEST2(tp->th_sport, length)) {
 425                         sum = tcp6_cksum(ip6, tp, length);
 426                         (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
 427                         if (sum != 0) {
 428                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 429                                 (void)printf(" (incorrect (-> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
 430                         } else
 431                                 (void)printf(" (correct)");
 432
 433                 }
 434         }
 435 #endif
 436
 437         length -= hlen;
 438         if (vflag > 1 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 439                 (void)printf(", seq %u", seq);
 440
 441                 if (length > 0) {
 442                         (void)printf(":%u", seq + length);
 443                 }
 444         }
 445
 446         if (flags & TH_ACK) {
 447                 (void)printf(", ack %u", ack);
 448         }
 449
 450         (void)printf(", win %d", win);
 451
 452         if (flags & TH_URG)
 453                 (void)printf(", urg %d", urp);
 454         /*
 455          * Handle any options.
 456          */
 457         if (hlen > sizeof(*tp)) {
 458                 register const u_char *cp;
 459                 register u_int i, opt, datalen;
 460                 register u_int len;
 461
 462                 hlen -= sizeof(*tp);
 463                 cp = (const u_char *)tp + sizeof(*tp);
 464                 printf(", options [");
 465                 while (hlen > 0) {
 466                         if (ch != '\0')
 467                                 putchar(ch);
 468                         TCHECK(*cp);
 469                         opt = *cp++;
 470                         if (ZEROLENOPT(opt))
 471                                 len = 1;
 472                         else {
 473                                 TCHECK(*cp);
 474                                 len = *cp++;    /* total including type, len */
 475                                 if (len < 2 || len > hlen)
 476                                         goto bad;
 477                                 --hlen;         /* account for length byte */
 478                         }
 479                         --hlen;                 /* account for type byte */
 480                         datalen = 0;
 481
 482 /* Bail if "l" bytes of data are not left or were not captured  */
 483 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 484
 485
 486                         printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
 487
 488                         switch (opt) {
 489
 490                         case TCPOPT_MAXSEG:
 491                                 datalen = 2;
 492                                 LENCHECK(datalen);
 493                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 494                                 break;
 495
 496                         case TCPOPT_WSCALE:
 497                                 datalen = 1;
 498                                 LENCHECK(datalen);
 499                                 (void)printf(" %u", *cp);
 500                                 break;
 501
 502                         case TCPOPT_SACK:
 503                                 datalen = len - 2;
 504                                 if (datalen % 8 != 0) {
 505                                         (void)printf("malformed sack");
 506                                 } else {
 507                                         u_int32_t s, e;
 508
 509                                         (void)printf(" %d ", datalen / 8);
 510                                         for (i = 0; i < datalen; i += 8) {
 511                                                 LENCHECK(i + 4);
 512                                                 s = EXTRACT_32BITS(cp + i);
 513                                                 LENCHECK(i + 8);
 514                                                 e = EXTRACT_32BITS(cp + i + 4);
 515                                                 if (threv) {
 516                                                         s -= thseq;
 517                                                         e -= thseq;
 518                                                 } else {
 519                                                         s -= thack;
 520                                                         e -= thack;
 521                                                 }
 522                                                 (void)printf("{%u:%u}", s, e);
 523                                         }
 524                                 }
 525                                 break;
 526
 527                         case TCPOPT_CC:
 528                         case TCPOPT_CCNEW:
 529                         case TCPOPT_CCECHO:
 530                         case TCPOPT_ECHO:
 531                         case TCPOPT_ECHOREPLY:
 532
 533                                 /*
 534                                  * those options share their semantics.
 535                                  * fall through
 536                                  */
 537                                 datalen = 4;
 538                                 LENCHECK(datalen);
 539                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 540                                 break;
 541
 542                         case TCPOPT_TIMESTAMP:
 543                                 datalen = 8;
 544                                 LENCHECK(datalen);
 545                                 (void)printf(" val %u ecr %u",
 546                                              EXTRACT_32BITS(cp),
 547                                              EXTRACT_32BITS(cp + 4));
 548                                 break;
 549
 550                         case TCPOPT_SIGNATURE:
 551                                 datalen = TCP_SIGLEN;
 552                                 LENCHECK(datalen);
 553 #ifdef HAVE_LIBCRYPTO
 554                                 switch (tcp_verify_signature(ip, tp,
 555                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 556
 557                                 case SIGNATURE_VALID:
 558                                         (void)printf("valid");
 559                                         break;
 560
 561                                 case SIGNATURE_INVALID:
 562                                         (void)printf("invalid");
 563                                         break;
 564
 565                                 case CANT_CHECK_SIGNATURE:
 566                                         (void)printf("can't check - ");
 567                                         for (i = 0; i < TCP_SIGLEN; ++i)
 568                                                 (void)printf("%02x", cp[i]);
 569                                         break;
 570                                 }
 571 #else
 572                                 for (i = 0; i < TCP_SIGLEN; ++i)
 573                                         (void)printf("%02x", cp[i]);
 574 #endif
 575                                 break;
 576
 577                         case TCPOPT_AUTH:
 578                                 (void)printf("keyid %d", *cp++);
 579                                 datalen = len - 3;
 580                                 for (i = 0; i < datalen; ++i) {
 581                                         LENCHECK(i);
 582                                         (void)printf("%02x", cp[i]);
 583                                 }
 584                                 break;
 585
 586
 587                         case TCPOPT_EOL:
 588                         case TCPOPT_NOP:
 589                         case TCPOPT_SACKOK:
 590                                 /*
 591                                  * Nothing interesting.
 592                                  * fall through
 593                                  */
 594                                 break;
 595
 596                         default:
 597                                 datalen = len - 2;
 598                                 for (i = 0; i < datalen; ++i) {
 599                                         LENCHECK(i);
 600                                         (void)printf("%02x", cp[i]);
 601                                 }
 602                                 break;
 603                         }
 604
 605                         /* Account for data printed */
 606                         cp += datalen;
 607                         hlen -= datalen;
 608
 609                         /* Check specification against observed length */
 610                         ++datalen;                      /* option octet */
 611                         if (!ZEROLENOPT(opt))
 612                                 ++datalen;              /* size octet */
 613                         if (datalen != len)
 614                                 (void)printf("[len %d]", len);
 615                         ch = ',';
 616                         if (opt == TCPOPT_EOL)
 617                                 break;
 618                 }
 619                 putchar(']');
 620         }
 621
 622         /*
 623          * Print length field before crawling down the stack.
 624          */
 625         printf(", length %u", length);
 626
 627         if (length <= 0)
 628                 return;
 629
 630         /*
 631          * Decode payload if necessary.
 632          */
 633         bp += TH_OFF(tp) * 4;
 634         if ((flags & TH_RST) && vflag) {
 635                 print_tcp_rst_data(bp, length);
 636                 return;
 637         }
 638
 639         if (sport == TELNET_PORT || dport == TELNET_PORT) {
 640                 if (!qflag && vflag)
 641                         telnet_print(bp, length);
 642         } else if (sport == BGP_PORT || dport == BGP_PORT)
 643                 bgp_print(bp, length);
 644         else if (sport == PPTP_PORT || dport == PPTP_PORT)
 645                 pptp_print(bp);
 646 #ifdef TCPDUMP_DO_SMB
 647         else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 648                 nbt_tcp_print(bp, length);
 649 #endif
 650         else if (sport == BEEP_PORT || dport == BEEP_PORT)
 651                 beep_print(bp, length);
 652         else if (length > 2 &&
 653                  (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
 654                   sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
 655                 /*
 656                  * TCP DNS query has 2byte length at the head.
 657                  * XXX packet could be unaligned, it can go strange
 658                  */
 659                 ns_print(bp + 2, length - 2, 0);
 660         } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 661                 msdp_print(bp, length);
 662         }
 663         else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
 664                 ldp_print(bp, length);
 665         }
 666
 667         return;
 668  bad:
 669         fputs("[bad opt]", stdout);
 670         if (ch != '\0')
 671                 putchar('>');
 672         return;
 673  trunc:
 674         fputs("[|tcp]", stdout);
 675         if (ch != '\0')
 676                 putchar('>');
 677 }
 678
 679 /*
 680  * RFC1122 says the following on data in RST segments:
 681  *
 682  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 683  *
 684  *            A TCP SHOULD allow a received RST segment to include data.
 685  *
 686  *            DISCUSSION
 687  *                 It has been suggested that a RST segment could contain
 688  *                 ASCII text that encoded and explained the cause of the
 689  *                 RST.  No standard has yet been established for such
 690  *                 data.
 691  *
 692  */
 693
 694 static void
 695 print_tcp_rst_data(register const u_char *sp, u_int length)
 696 {
 697         int c;
 698
 699         if (TTEST2(*sp, length))
 700                 printf(" [RST");
 701         else
 702                 printf(" [!RST");
 703         if (length > MAX_RST_DATA_LEN) {
 704                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 705                 putchar('+');                   /* indicate we truncate */
 706         }
 707         putchar(' ');
 708         while (length-- && sp <= snapend) {
 709                 c = *sp++;
 710                 safeputchar(c);
 711         }
 712         putchar(']');
 713 }
 714
 715 #ifdef HAVE_LIBCRYPTO
 716 static int
 717 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
 718                      const u_char *data, int length, const u_char *rcvsig)
 719 {
 720         struct tcphdr tp1;
 721         u_char sig[TCP_SIGLEN];
 722         char zero_proto = 0;
 723         MD5_CTX ctx;
 724         u_int16_t savecsum, tlen;
 725 #ifdef INET6
 726         struct ip6_hdr *ip6;
 727 #endif
 728         u_int32_t len32;
 729         u_int8_t nxt;
 730
 731         tp1 = *tp;
 732
 733         if (tcpmd5secret == NULL)
 734                 return (CANT_CHECK_SIGNATURE);
 735
 736         MD5_Init(&ctx);
 737         /*
 738          * Step 1: Update MD5 hash with IP pseudo-header.
 739          */
 740         if (IP_V(ip) == 4) {
 741                 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
 742                 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
 743                 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
 744                 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
 745                 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
 746                 tlen = htons(tlen);
 747                 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
 748 #ifdef INET6
 749         } else if (IP_V(ip) == 6) {
 750                 ip6 = (struct ip6_hdr *)ip;
 751                 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 752                 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 753                 len32 = htonl(ntohs(ip6->ip6_plen));
 754                 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
 755                 nxt = 0;
 756                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 757                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 758                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 759                 nxt = IPPROTO_TCP;
 760                 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
 761 #endif
 762         } else
 763                 return (CANT_CHECK_SIGNATURE);
 764
 765         /*
 766          * Step 2: Update MD5 hash with TCP header, excluding options.
 767          * The TCP checksum must be set to zero.
 768          */
 769         savecsum = tp1.th_sum;
 770         tp1.th_sum = 0;
 771         MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
 772         tp1.th_sum = savecsum;
 773         /*
 774          * Step 3: Update MD5 hash with TCP segment data, if present.
 775          */
 776         if (length > 0)
 777                 MD5_Update(&ctx, data, length);
 778         /*
 779          * Step 4: Update MD5 hash with shared secret.
 780          */
 781         MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
 782         MD5_Final(sig, &ctx);
 783
 784         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 785                 return (SIGNATURE_VALID);
 786         else
 787                 return (SIGNATURE_INVALID);
 788 }
 789 #endif /* HAVE_LIBCRYPTO */
 790
 791 /*
 792  * Local Variables:
 793  * c-style: whitesmith
 794  * c-basic-offset: 8
 795  * End:
 796  */