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 /* \summary: TCP printer */
  27
  28 #ifndef lint
  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 "netdissect-stdinc.h"
  38
  39 #include <stdlib.h>
  40 #include <string.h>
  41
  42 #define ND_LONGJMP_FROM_TCHECK
  43 #include "netdissect.h"
  44 #include "addrtoname.h"
  45 #include "extract.h"
  46
  47 #include "tcp.h"
  48
  49 #include "ip.h"
  50 #include "ip6.h"
  51 #include "ipproto.h"
  52 #include "rpc_auth.h"
  53 #include "rpc_msg.h"
  54
  55 #ifdef HAVE_LIBCRYPTO
  56 #include <openssl/md5.h>
  57 #include "signature.h"
  58
  59 static int tcp_verify_signature(netdissect_options *ndo,
  60                                 const struct ip *ip, const struct tcphdr *tp,
  61                                 const u_char *data, u_int length, const u_char *rcvsig);
  62 #endif
  63
  64 static void print_tcp_rst_data(netdissect_options *, const u_char *sp, u_int length);
  65 static void print_tcp_fastopen_option(netdissect_options *ndo, const u_char *cp,
  66                                       u_int datalen);
  67
  68 #define MAX_RST_DATA_LEN        30
  69
  70
  71 struct tha {
  72         nd_ipv4 src;
  73         nd_ipv4 dst;
  74         u_int port;
  75 };
  76
  77 struct tcp_seq_hash {
  78         struct tcp_seq_hash *nxt;
  79         struct tha addr;
  80         uint32_t seq;
  81         uint32_t ack;
  82 };
  83
  84 struct tha6 {
  85         nd_ipv6 src;
  86         nd_ipv6 dst;
  87         u_int port;
  88 };
  89
  90 struct tcp_seq_hash6 {
  91         struct tcp_seq_hash6 *nxt;
  92         struct tha6 addr;
  93         uint32_t seq;
  94         uint32_t ack;
  95 };
  96
  97 #define TSEQ_HASHSIZE 919
  98
  99 /* These tcp options do not have the size octet */
 100 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
 101
 102 static struct tcp_seq_hash tcp_seq_hash4[TSEQ_HASHSIZE];
 103 static struct tcp_seq_hash6 tcp_seq_hash6[TSEQ_HASHSIZE];
 104
 105 const struct tok tcp_flag_values[] = {
 106         { TH_FIN, "F" },
 107         { TH_SYN, "S" },
 108         { TH_RST, "R" },
 109         { TH_PUSH, "P" },
 110         { TH_ACK, "." },
 111         { TH_URG, "U" },
 112         { TH_ECNECHO, "E" },
 113         { TH_CWR, "W" },
 114         { 0, NULL }
 115 };
 116
 117 static const struct tok tcp_option_values[] = {
 118         { TCPOPT_EOL, "eol" },
 119         { TCPOPT_NOP, "nop" },
 120         { TCPOPT_MAXSEG, "mss" },
 121         { TCPOPT_WSCALE, "wscale" },
 122         { TCPOPT_SACKOK, "sackOK" },
 123         { TCPOPT_SACK, "sack" },
 124         { TCPOPT_ECHO, "echo" },
 125         { TCPOPT_ECHOREPLY, "echoreply" },
 126         { TCPOPT_TIMESTAMP, "TS" },
 127         { TCPOPT_CC, "cc" },
 128         { TCPOPT_CCNEW, "ccnew" },
 129         { TCPOPT_CCECHO, "" },
 130         { TCPOPT_SIGNATURE, "md5" },
 131         { TCPOPT_SCPS, "scps" },
 132         { TCPOPT_UTO, "uto" },
 133         { TCPOPT_TCPAO, "tcp-ao" },
 134         { TCPOPT_MPTCP, "mptcp" },
 135         { TCPOPT_FASTOPEN, "tfo" },
 136         { TCPOPT_EXPERIMENT2, "exp" },
 137         { 0, NULL }
 138 };
 139
 140 static uint16_t
 141 tcp_cksum(netdissect_options *ndo,
 142           const struct ip *ip,
 143           const struct tcphdr *tp,
 144           u_int len)
 145 {
 146         return nextproto4_cksum(ndo, ip, (const uint8_t *)tp, len, len,
 147                                 IPPROTO_TCP);
 148 }
 149
 150 static uint16_t
 151 tcp6_cksum(netdissect_options *ndo,
 152            const struct ip6_hdr *ip6,
 153            const struct tcphdr *tp,
 154            u_int len)
 155 {
 156         return nextproto6_cksum(ndo, ip6, (const uint8_t *)tp, len, len,
 157                                 IPPROTO_TCP);
 158 }
 159
 160 void
 161 tcp_print(netdissect_options *ndo,
 162           const u_char *bp, u_int length,
 163           const u_char *bp2, int fragmented)
 164 {
 165         const struct tcphdr *tp;
 166         const struct ip *ip;
 167         u_char flags;
 168         u_int hlen;
 169         char ch;
 170         uint16_t sport, dport, win, urp;
 171         uint32_t seq, ack, thseq, thack;
 172         u_int utoval;
 173         uint16_t magic;
 174         int rev;
 175         const struct ip6_hdr *ip6;
 176
 177         ndo->ndo_protocol = "tcp";
 178         tp = (const struct tcphdr *)bp;
 179         ip = (const struct ip *)bp2;
 180         if (IP_V(ip) == 6)
 181                 ip6 = (const struct ip6_hdr *)bp2;
 182         else
 183                 ip6 = NULL;
 184         ch = '\0';
 185         if (!ND_TTEST_2(tp->th_dport)) {
 186                 if (ip6) {
 187                         ND_PRINT("%s > %s:",
 188                                  GET_IP6ADDR_STRING(ip6->ip6_src),
 189                                  GET_IP6ADDR_STRING(ip6->ip6_dst));
 190                 } else {
 191                         ND_PRINT("%s > %s:",
 192                                  GET_IPADDR_STRING(ip->ip_src),
 193                                  GET_IPADDR_STRING(ip->ip_dst));
 194                 }
 195                 nd_trunc_longjmp(ndo);
 196         }
 197
 198         sport = GET_BE_U_2(tp->th_sport);
 199         dport = GET_BE_U_2(tp->th_dport);
 200
 201         if (ip6) {
 202                 if (GET_U_1(ip6->ip6_nxt) == IPPROTO_TCP) {
 203                         ND_PRINT("%s.%s > %s.%s: ",
 204                                  GET_IP6ADDR_STRING(ip6->ip6_src),
 205                                  tcpport_string(ndo, sport),
 206                                  GET_IP6ADDR_STRING(ip6->ip6_dst),
 207                                  tcpport_string(ndo, dport));
 208                 } else {
 209                         ND_PRINT("%s > %s: ",
 210                                  tcpport_string(ndo, sport), tcpport_string(ndo, dport));
 211                 }
 212         } else {
 213                 if (GET_U_1(ip->ip_p) == IPPROTO_TCP) {
 214                         ND_PRINT("%s.%s > %s.%s: ",
 215                                  GET_IPADDR_STRING(ip->ip_src),
 216                                  tcpport_string(ndo, sport),
 217                                  GET_IPADDR_STRING(ip->ip_dst),
 218                                  tcpport_string(ndo, dport));
 219                 } else {
 220                         ND_PRINT("%s > %s: ",
 221                                  tcpport_string(ndo, sport), tcpport_string(ndo, dport));
 222                 }
 223         }
 224
 225         hlen = TH_OFF(tp) * 4;
 226
 227         if (hlen < sizeof(*tp)) {
 228                 ND_PRINT(" tcp %u [bad hdr length %u - too short, < %zu]",
 229                          length - hlen, hlen, sizeof(*tp));
 230                 goto invalid;
 231         }
 232
 233         seq = GET_BE_U_4(tp->th_seq);
 234         ack = GET_BE_U_4(tp->th_ack);
 235         win = GET_BE_U_2(tp->th_win);
 236         urp = GET_BE_U_2(tp->th_urp);
 237
 238         if (ndo->ndo_qflag) {
 239                 ND_PRINT("tcp %u", length - hlen);
 240                 if (hlen > length) {
 241                         ND_PRINT(" [bad hdr length %u - too long, > %u]",
 242                                  hlen, length);
 243                         goto invalid;
 244                 }
 245                 return;
 246         }
 247
 248         flags = GET_U_1(tp->th_flags);
 249         ND_PRINT("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 250
 251         if (!ndo->ndo_Sflag && (flags & TH_ACK)) {
 252                 /*
 253                  * Find (or record) the initial sequence numbers for
 254                  * this conversation.  (we pick an arbitrary
 255                  * collating order so there's only one entry for
 256                  * both directions).
 257                  */
 258                 rev = 0;
 259                 if (ip6) {
 260                         struct tcp_seq_hash6 *th;
 261                         struct tcp_seq_hash6 *tcp_seq_hash;
 262                         const void *src, *dst;
 263                         struct tha6 tha;
 264
 265                         tcp_seq_hash = tcp_seq_hash6;
 266                         src = (const void *)ip6->ip6_src;
 267                         dst = (const void *)ip6->ip6_dst;
 268                         if (sport > dport)
 269                                 rev = 1;
 270                         else if (sport == dport) {
 271                                 if (UNALIGNED_MEMCMP(src, dst, sizeof(ip6->ip6_dst)) > 0)
 272                                         rev = 1;
 273                         }
 274                         if (rev) {
 275                                 UNALIGNED_MEMCPY(&tha.src, dst, sizeof(ip6->ip6_dst));
 276                                 UNALIGNED_MEMCPY(&tha.dst, src, sizeof(ip6->ip6_src));
 277                                 tha.port = ((u_int)dport) << 16 | sport;
 278                         } else {
 279                                 UNALIGNED_MEMCPY(&tha.dst, dst, sizeof(ip6->ip6_dst));
 280                                 UNALIGNED_MEMCPY(&tha.src, src, sizeof(ip6->ip6_src));
 281                                 tha.port = ((u_int)sport) << 16 | dport;
 282                         }
 283
 284                         for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 285                              th->nxt; th = th->nxt)
 286                                 if (memcmp((char *)&tha, (char *)&th->addr,
 287                                            sizeof(th->addr)) == 0)
 288                                         break;
 289
 290                         if (!th->nxt || (flags & TH_SYN)) {
 291                                 /* didn't find it or new conversation */
 292                                 /* calloc() return used by the 'tcp_seq_hash6'
 293                                    hash table: do not free() */
 294                                 if (th->nxt == NULL) {
 295                                         th->nxt = (struct tcp_seq_hash6 *)
 296                                                 calloc(1, sizeof(*th));
 297                                         if (th->nxt == NULL)
 298                                                 (*ndo->ndo_error)(ndo,
 299                                                         S_ERR_ND_MEM_ALLOC,
 300                                                         "%s: calloc", __func__);
 301                                 }
 302                                 th->addr = tha;
 303                                 if (rev)
 304                                         th->ack = seq, th->seq = ack - 1;
 305                                 else
 306                                         th->seq = seq, th->ack = ack - 1;
 307                         } else {
 308                                 if (rev)
 309                                         seq -= th->ack, ack -= th->seq;
 310                                 else
 311                                         seq -= th->seq, ack -= th->ack;
 312                         }
 313
 314                         thseq = th->seq;
 315                         thack = th->ack;
 316                 } else {
 317                         struct tcp_seq_hash *th;
 318                         struct tcp_seq_hash *tcp_seq_hash;
 319                         struct tha tha;
 320
 321                         tcp_seq_hash = tcp_seq_hash4;
 322                         if (sport > dport)
 323                                 rev = 1;
 324                         else if (sport == dport) {
 325                                 if (UNALIGNED_MEMCMP(ip->ip_src, ip->ip_dst, sizeof(ip->ip_dst)) > 0)
 326                                         rev = 1;
 327                         }
 328                         if (rev) {
 329                                 UNALIGNED_MEMCPY(&tha.src, ip->ip_dst,
 330                                                  sizeof(ip->ip_dst));
 331                                 UNALIGNED_MEMCPY(&tha.dst, ip->ip_src,
 332                                                  sizeof(ip->ip_src));
 333                                 tha.port = ((u_int)dport) << 16 | sport;
 334                         } else {
 335                                 UNALIGNED_MEMCPY(&tha.dst, ip->ip_dst,
 336                                                  sizeof(ip->ip_dst));
 337                                 UNALIGNED_MEMCPY(&tha.src, ip->ip_src,
 338                                                  sizeof(ip->ip_src));
 339                                 tha.port = ((u_int)sport) << 16 | dport;
 340                         }
 341
 342                         for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 343                              th->nxt; th = th->nxt)
 344                                 if (memcmp((char *)&tha, (char *)&th->addr,
 345                                            sizeof(th->addr)) == 0)
 346                                         break;
 347
 348                         if (!th->nxt || (flags & TH_SYN)) {
 349                                 /* didn't find it or new conversation */
 350                                 /* calloc() return used by the 'tcp_seq_hash4'
 351                                    hash table: do not free() */
 352                                 if (th->nxt == NULL) {
 353                                         th->nxt = (struct tcp_seq_hash *)
 354                                                 calloc(1, sizeof(*th));
 355                                         if (th->nxt == NULL)
 356                                                 (*ndo->ndo_error)(ndo,
 357                                                         S_ERR_ND_MEM_ALLOC,
 358                                                         "%s: calloc", __func__);
 359                                 }
 360                                 th->addr = tha;
 361                                 if (rev)
 362                                         th->ack = seq, th->seq = ack - 1;
 363                                 else
 364                                         th->seq = seq, th->ack = ack - 1;
 365                         } else {
 366                                 if (rev)
 367                                         seq -= th->ack, ack -= th->seq;
 368                                 else
 369                                         seq -= th->seq, ack -= th->ack;
 370                         }
 371
 372                         thseq = th->seq;
 373                         thack = th->ack;
 374                 }
 375         } else {
 376                 /*fool gcc*/
 377                 thseq = thack = rev = 0;
 378         }
 379         if (hlen > length) {
 380                 ND_PRINT(" [bad hdr length %u - too long, > %u]",
 381                          hlen, length);
 382                 goto invalid;
 383         }
 384
 385         if (ndo->ndo_vflag && !ndo->ndo_Kflag && !fragmented) {
 386                 /* Check the checksum, if possible. */
 387                 uint16_t sum, tcp_sum;
 388
 389                 if (IP_V(ip) == 4) {
 390                         if (ND_TTEST_LEN(tp->th_sport, length)) {
 391                                 sum = tcp_cksum(ndo, ip, tp, length);
 392                                 tcp_sum = GET_BE_U_2(tp->th_sum);
 393
 394                                 ND_PRINT(", cksum 0x%04x", tcp_sum);
 395                                 if (sum != 0)
 396                                         ND_PRINT(" (incorrect -> 0x%04x)",
 397                                             in_cksum_shouldbe(tcp_sum, sum));
 398                                 else
 399                                         ND_PRINT(" (correct)");
 400                         }
 401                 } else if (IP_V(ip) == 6) {
 402                         if (ND_TTEST_LEN(tp->th_sport, length)) {
 403                                 sum = tcp6_cksum(ndo, ip6, tp, length);
 404                                 tcp_sum = GET_BE_U_2(tp->th_sum);
 405
 406                                 ND_PRINT(", cksum 0x%04x", tcp_sum);
 407                                 if (sum != 0)
 408                                         ND_PRINT(" (incorrect -> 0x%04x)",
 409                                             in_cksum_shouldbe(tcp_sum, sum));
 410                                 else
 411                                         ND_PRINT(" (correct)");
 412
 413                         }
 414                 }
 415         }
 416
 417         length -= hlen;
 418         if (ndo->ndo_vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 419                 ND_PRINT(", seq %u", seq);
 420
 421                 if (length > 0) {
 422                         ND_PRINT(":%u", seq + length);
 423                 }
 424         }
 425
 426         if (flags & TH_ACK) {
 427                 ND_PRINT(", ack %u", ack);
 428         }
 429
 430         ND_PRINT(", win %u", win);
 431
 432         if (flags & TH_URG)
 433                 ND_PRINT(", urg %u", urp);
 434         /*
 435          * Handle any options.
 436          */
 437         if (hlen > sizeof(*tp)) {
 438                 const u_char *cp;
 439                 u_int i, opt, datalen;
 440                 u_int len;
 441
 442                 hlen -= sizeof(*tp);
 443                 cp = (const u_char *)tp + sizeof(*tp);
 444                 ND_PRINT(", options [");
 445                 while (hlen > 0) {
 446                         if (ch != '\0')
 447                                 ND_PRINT("%c", ch);
 448                         opt = GET_U_1(cp);
 449                         cp++;
 450                         if (ZEROLENOPT(opt))
 451                                 len = 1;
 452                         else {
 453                                 len = GET_U_1(cp);
 454                                 cp++;   /* total including type, len */
 455                                 if (len < 2 || len > hlen)
 456                                         goto bad;
 457                                 --hlen;         /* account for length byte */
 458                         }
 459                         --hlen;                 /* account for type byte */
 460                         datalen = 0;
 461
 462 /* Bail if "l" bytes of data are not left or were not captured  */
 463 #define LENCHECK(l) { if ((l) > hlen) goto bad; }
 464
 465
 466                         ND_PRINT("%s", tok2str(tcp_option_values, "unknown-%u", opt));
 467
 468                         switch (opt) {
 469
 470                         case TCPOPT_MAXSEG:
 471                                 datalen = 2;
 472                                 LENCHECK(datalen);
 473                                 ND_PRINT(" %u", GET_BE_U_2(cp));
 474                                 break;
 475
 476                         case TCPOPT_WSCALE:
 477                                 datalen = 1;
 478                                 LENCHECK(datalen);
 479                                 ND_PRINT(" %u", GET_U_1(cp));
 480                                 break;
 481
 482                         case TCPOPT_SACK:
 483                                 datalen = len - 2;
 484                                 if (datalen % 8 != 0) {
 485                                         ND_PRINT(" invalid sack");
 486                                 } else {
 487                                         uint32_t s, e;
 488
 489                                         ND_PRINT(" %u ", datalen / 8);
 490                                         for (i = 0; i < datalen; i += 8) {
 491                                                 LENCHECK(i + 4);
 492                                                 s = GET_BE_U_4(cp + i);
 493                                                 LENCHECK(i + 8);
 494                                                 e = GET_BE_U_4(cp + i + 4);
 495                                                 if (rev) {
 496                                                         s -= thseq;
 497                                                         e -= thseq;
 498                                                 } else {
 499                                                         s -= thack;
 500                                                         e -= thack;
 501                                                 }
 502                                                 ND_PRINT("{%u:%u}", s, e);
 503                                         }
 504                                 }
 505                                 break;
 506
 507                         case TCPOPT_CC:
 508                         case TCPOPT_CCNEW:
 509                         case TCPOPT_CCECHO:
 510                         case TCPOPT_ECHO:
 511                         case TCPOPT_ECHOREPLY:
 512
 513                                 /*
 514                                  * those options share their semantics.
 515                                  * fall through
 516                                  */
 517                                 datalen = 4;
 518                                 LENCHECK(datalen);
 519                                 ND_PRINT(" %u", GET_BE_U_4(cp));
 520                                 break;
 521
 522                         case TCPOPT_TIMESTAMP:
 523                                 datalen = 8;
 524                                 LENCHECK(datalen);
 525                                 ND_PRINT(" val %u ecr %u",
 526                                              GET_BE_U_4(cp),
 527                                              GET_BE_U_4(cp + 4));
 528                                 break;
 529
 530                         case TCPOPT_SIGNATURE:
 531                                 datalen = TCP_SIGLEN;
 532                                 LENCHECK(datalen);
 533                                 ND_TCHECK_LEN(cp, datalen);
 534                                 ND_PRINT(" ");
 535 #ifdef HAVE_LIBCRYPTO
 536                                 switch (tcp_verify_signature(ndo, ip, tp,
 537                                                              bp + TH_OFF(tp) * 4, length, cp)) {
 538
 539                                 case SIGNATURE_VALID:
 540                                         ND_PRINT("valid");
 541                                         break;
 542
 543                                 case SIGNATURE_INVALID:
 544                                         nd_print_invalid(ndo);
 545                                         break;
 546
 547                                 case CANT_CHECK_SIGNATURE:
 548                                         ND_PRINT("can't check - ");
 549                                         for (i = 0; i < TCP_SIGLEN; ++i)
 550                                                 ND_PRINT("%02x",
 551                                                          GET_U_1(cp + i));
 552                                         break;
 553                                 }
 554 #else
 555                                 for (i = 0; i < TCP_SIGLEN; ++i)
 556                                         ND_PRINT("%02x", GET_U_1(cp + i));
 557 #endif
 558                                 break;
 559
 560                         case TCPOPT_SCPS:
 561                                 datalen = 2;
 562                                 LENCHECK(datalen);
 563                                 ND_PRINT(" cap %02x id %u", GET_U_1(cp),
 564                                          GET_U_1(cp + 1));
 565                                 break;
 566
 567                         case TCPOPT_TCPAO:
 568                                 datalen = len - 2;
 569                                 /* RFC 5925 Section 2.2:
 570                                  * "The Length value MUST be greater than or equal to 4."
 571                                  * (This includes the Kind and Length fields already processed
 572                                  * at this point.)
 573                                  */
 574                                 if (datalen < 2) {
 575                                         nd_print_invalid(ndo);
 576                                 } else {
 577                                         LENCHECK(1);
 578                                         ND_PRINT(" keyid %u", GET_U_1(cp));
 579                                         LENCHECK(2);
 580                                         ND_PRINT(" rnextkeyid %u",
 581                                                  GET_U_1(cp + 1));
 582                                         if (datalen > 2) {
 583                                                 ND_PRINT(" mac 0x");
 584                                                 for (i = 2; i < datalen; i++) {
 585                                                         LENCHECK(i + 1);
 586                                                         ND_PRINT("%02x",
 587                                                                  GET_U_1(cp + i));
 588                                                 }
 589                                         }
 590                                 }
 591                                 break;
 592
 593                         case TCPOPT_EOL:
 594                         case TCPOPT_NOP:
 595                         case TCPOPT_SACKOK:
 596                                 /*
 597                                  * Nothing interesting.
 598                                  * fall through
 599                                  */
 600                                 break;
 601
 602                         case TCPOPT_UTO:
 603                                 datalen = 2;
 604                                 LENCHECK(datalen);
 605                                 utoval = GET_BE_U_2(cp);
 606                                 ND_PRINT(" 0x%x", utoval);
 607                                 if (utoval & 0x0001)
 608                                         utoval = (utoval >> 1) * 60;
 609                                 else
 610                                         utoval >>= 1;
 611                                 ND_PRINT(" %u", utoval);
 612                                 break;
 613
 614                         case TCPOPT_MPTCP:
 615                                 datalen = len - 2;
 616                                 LENCHECK(datalen);
 617                                 /* FIXME: Proof-read mptcp_print() and if it
 618                                  * always covers all bytes when it returns 1,
 619                                  * only do ND_TCHECK_LEN() if it returned 0.
 620                                  */
 621                                 ND_TCHECK_LEN(cp, datalen);
 622                                 if (!mptcp_print(ndo, cp-2, len, flags))
 623                                         goto bad;
 624                                 break;
 625
 626                         case TCPOPT_FASTOPEN:
 627                                 datalen = len - 2;
 628                                 LENCHECK(datalen);
 629                                 ND_TCHECK_LEN(cp, datalen);
 630                                 ND_PRINT(" ");
 631                                 print_tcp_fastopen_option(ndo, cp, datalen);
 632                                 break;
 633
 634                         case TCPOPT_EXPERIMENT2:
 635                                 datalen = len - 2;
 636                                 LENCHECK(datalen);
 637                                 ND_TCHECK_LEN(cp, datalen);
 638                                 if (datalen < 2)
 639                                         goto bad;
 640                                 /* RFC6994 */
 641                                 magic = GET_BE_U_2(cp);
 642                                 ND_PRINT("-");
 643
 644                                 switch(magic) {
 645
 646                                 case 0xf989: /* TCP Fast Open RFC 7413 */
 647                                         ND_PRINT("tfo");
 648                                         print_tcp_fastopen_option(ndo, cp + 2, datalen - 2);
 649                                         break;
 650
 651                                 default:
 652                                         /* Unknown magic number */
 653                                         ND_PRINT("%04x", magic);
 654                                         break;
 655                                 }
 656                                 break;
 657
 658                         default:
 659                                 datalen = len - 2;
 660                                 if (datalen)
 661                                         ND_PRINT(" 0x");
 662                                 for (i = 0; i < datalen; ++i) {
 663                                         LENCHECK(i + 1);
 664                                         ND_PRINT("%02x", GET_U_1(cp + i));
 665                                 }
 666                                 break;
 667                         }
 668
 669                         /* Account for data printed */
 670                         cp += datalen;
 671                         hlen -= datalen;
 672
 673                         /* Check specification against observed length */
 674                         ++datalen;              /* option octet */
 675                         if (!ZEROLENOPT(opt))
 676                                 ++datalen;      /* size octet */
 677                         if (datalen != len)
 678                                 ND_PRINT("[len %u]", len);
 679                         ch = ',';
 680                         if (opt == TCPOPT_EOL)
 681                                 break;
 682                 }
 683                 ND_PRINT("]");
 684         }
 685
 686         /*
 687          * Print length field before crawling down the stack.
 688          */
 689         ND_PRINT(", length %u", length);
 690
 691         if (length <= 0)
 692                 return;
 693
 694         /*
 695          * Decode payload if necessary.
 696          */
 697         bp += TH_OFF(tp) * 4;
 698         if ((flags & TH_RST) && ndo->ndo_vflag) {
 699                 print_tcp_rst_data(ndo, bp, length);
 700                 return;
 701         }
 702
 703         if (ndo->ndo_packettype) {
 704                 switch (ndo->ndo_packettype) {
 705                 case PT_ZMTP1:
 706                         zmtp1_print(ndo, bp, length);
 707                         break;
 708                 case PT_RESP:
 709                         resp_print(ndo, bp, length);
 710                         break;
 711                 case PT_DOMAIN:
 712                         /* over_tcp: TRUE, is_mdns: FALSE */
 713                         domain_print(ndo, bp, length, TRUE, FALSE);
 714                         break;
 715                 }
 716                 return;
 717         }
 718
 719         if (IS_SRC_OR_DST_PORT(TELNET_PORT)) {
 720                 telnet_print(ndo, bp, length);
 721         } else if (IS_SRC_OR_DST_PORT(SMTP_PORT)) {
 722                 ND_PRINT(": ");
 723                 smtp_print(ndo, bp, length);
 724         } else if (IS_SRC_OR_DST_PORT(WHOIS_PORT)) {
 725                 ND_PRINT(": ");
 726                 ndo->ndo_protocol = "whois";    /* needed by txtproto_print() */
 727                 txtproto_print(ndo, bp, length, NULL, 0); /* RFC 3912 */
 728         } else if (IS_SRC_OR_DST_PORT(BGP_PORT))
 729                 bgp_print(ndo, bp, length);
 730         else if (IS_SRC_OR_DST_PORT(PPTP_PORT))
 731                 pptp_print(ndo, bp);
 732         else if (IS_SRC_OR_DST_PORT(REDIS_PORT))
 733                 resp_print(ndo, bp, length);
 734         else if (IS_SRC_OR_DST_PORT(SSH_PORT))
 735                 ssh_print(ndo, bp, length);
 736 #ifdef ENABLE_SMB
 737         else if (IS_SRC_OR_DST_PORT(NETBIOS_SSN_PORT))
 738                 nbt_tcp_print(ndo, bp, length);
 739         else if (IS_SRC_OR_DST_PORT(SMB_PORT))
 740                 smb_tcp_print(ndo, bp, length);
 741 #endif
 742         else if (IS_SRC_OR_DST_PORT(BEEP_PORT))
 743                 beep_print(ndo, bp, length);
 744         else if (IS_SRC_OR_DST_PORT(OPENFLOW_PORT_OLD) || IS_SRC_OR_DST_PORT(OPENFLOW_PORT_IANA))
 745                 openflow_print(ndo, bp, length);
 746         else if (IS_SRC_OR_DST_PORT(FTP_PORT)) {
 747                 ND_PRINT(": ");
 748                 ftp_print(ndo, bp, length);
 749         } else if (IS_SRC_OR_DST_PORT(HTTP_PORT) || IS_SRC_OR_DST_PORT(HTTP_PORT_ALT)) {
 750                 ND_PRINT(": ");
 751                 http_print(ndo, bp, length);
 752         } else if (IS_SRC_OR_DST_PORT(RTSP_PORT) || IS_SRC_OR_DST_PORT(RTSP_PORT_ALT)) {
 753                 ND_PRINT(": ");
 754                 rtsp_print(ndo, bp, length);
 755         } else if (IS_SRC_OR_DST_PORT(NAMESERVER_PORT)) {
 756                 /* over_tcp: TRUE, is_mdns: FALSE */
 757                 domain_print(ndo, bp, length, TRUE, FALSE);
 758         } else if (IS_SRC_OR_DST_PORT(MSDP_PORT)) {
 759                 msdp_print(ndo, bp, length);
 760         } else if (IS_SRC_OR_DST_PORT(RPKI_RTR_PORT)) {
 761                 rpki_rtr_print(ndo, bp, length);
 762         } else if (IS_SRC_OR_DST_PORT(LDP_PORT)) {
 763                 ldp_print(ndo, bp, length);
 764         } else if ((IS_SRC_OR_DST_PORT(NFS_PORT)) &&
 765                  length >= 4) {
 766                 /*
 767                  * If data present, header length valid, and NFS port used,
 768                  * assume NFS.
 769                  * Pass offset of data plus 4 bytes for RPC TCP msg length
 770                  * to NFS print routines.
 771                  */
 772                 uint32_t fraglen;
 773                 const struct sunrpc_msg *rp;
 774                 enum sunrpc_msg_type direction;
 775
 776                 fraglen = GET_BE_U_4(bp) & 0x7FFFFFFF;
 777                 if (fraglen > (length) - 4)
 778                         fraglen = (length) - 4;
 779                 rp = (const struct sunrpc_msg *)(bp + 4);
 780                 if (ND_TTEST_4(rp->rm_direction)) {
 781                         direction = (enum sunrpc_msg_type) GET_BE_U_4(rp->rm_direction);
 782                         if (dport == NFS_PORT && direction == SUNRPC_CALL) {
 783                                 ND_PRINT(": NFS request xid %u ",
 784                                          GET_BE_U_4(rp->rm_xid));
 785                                 nfsreq_noaddr_print(ndo, (const u_char *)rp, fraglen, (const u_char *)ip);
 786                                 return;
 787                         }
 788                         if (sport == NFS_PORT && direction == SUNRPC_REPLY) {
 789                                 ND_PRINT(": NFS reply xid %u ",
 790                                          GET_BE_U_4(rp->rm_xid));
 791                                 nfsreply_noaddr_print(ndo, (const u_char *)rp, fraglen, (const u_char *)ip);
 792                                 return;
 793                         }
 794                 }
 795         }
 796
 797         return;
 798 bad:
 799         ND_PRINT("[bad opt]");
 800         if (ch != '\0')
 801                 ND_PRINT("]");
 802         return;
 803 invalid:
 804         nd_print_invalid(ndo);
 805 }
 806
 807 /*
 808  * RFC1122 says the following on data in RST segments:
 809  *
 810  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 811  *
 812  *            A TCP SHOULD allow a received RST segment to include data.
 813  *
 814  *            DISCUSSION
 815  *                 It has been suggested that a RST segment could contain
 816  *                 ASCII text that encoded and explained the cause of the
 817  *                 RST.  No standard has yet been established for such
 818  *                 data.
 819  *
 820  */
 821
 822 static void
 823 print_tcp_rst_data(netdissect_options *ndo,
 824                    const u_char *sp, u_int length)
 825 {
 826         ND_PRINT(ND_TTEST_LEN(sp, length) ? " [RST" : " [!RST");
 827         if (length > MAX_RST_DATA_LEN) {
 828                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 829                 ND_PRINT("+");                  /* indicate we truncate */
 830         }
 831         ND_PRINT(" ");
 832         (void)nd_printn(ndo, sp, length, ndo->ndo_snapend);
 833         ND_PRINT("]");
 834 }
 835
 836 static void
 837 print_tcp_fastopen_option(netdissect_options *ndo, const u_char *cp,
 838                           u_int datalen)
 839 {
 840         u_int i;
 841
 842         if (datalen == 0) {
 843                 /* Fast Open Cookie Request */
 844                 ND_PRINT(" cookiereq");
 845         } else {
 846                 /* Fast Open Cookie */
 847                 if (datalen % 2 != 0 || datalen < 4 || datalen > 16) {
 848                         nd_print_invalid(ndo);
 849                 } else {
 850                         ND_PRINT(" cookie ");
 851                         for (i = 0; i < datalen; ++i)
 852                                 ND_PRINT("%02x", GET_U_1(cp + i));
 853                 }
 854         }
 855 }
 856
 857 #ifdef HAVE_LIBCRYPTO
 858 USES_APPLE_DEPRECATED_API
 859 static int
 860 tcp_verify_signature(netdissect_options *ndo,
 861                      const struct ip *ip, const struct tcphdr *tp,
 862                      const u_char *data, u_int length, const u_char *rcvsig)
 863 {
 864         struct tcphdr tp1;
 865         u_char sig[TCP_SIGLEN];
 866         char zero_proto = 0;
 867         MD5_CTX ctx;
 868         uint16_t savecsum, tlen;
 869         const struct ip6_hdr *ip6;
 870         uint32_t len32;
 871         uint8_t nxt;
 872
 873         if (!ND_TTEST_LEN(data, length)) {
 874                 ND_PRINT("snaplen too short, ");
 875                 return (CANT_CHECK_SIGNATURE);
 876         }
 877
 878         tp1 = *tp;
 879
 880         if (ndo->ndo_sigsecret == NULL) {
 881                 ND_PRINT("shared secret not supplied with -M, ");
 882                 return (CANT_CHECK_SIGNATURE);
 883         }
 884
 885         MD5_Init(&ctx);
 886         /*
 887          * Step 1: Update MD5 hash with IP pseudo-header.
 888          */
 889         if (IP_V(ip) == 4) {
 890                 MD5_Update(&ctx, (const char *)&ip->ip_src, sizeof(ip->ip_src));
 891                 MD5_Update(&ctx, (const char *)&ip->ip_dst, sizeof(ip->ip_dst));
 892                 MD5_Update(&ctx, (const char *)&zero_proto, sizeof(zero_proto));
 893                 MD5_Update(&ctx, (const char *)&ip->ip_p, sizeof(ip->ip_p));
 894                 tlen = GET_BE_U_2(ip->ip_len) - IP_HL(ip) * 4;
 895                 tlen = htons(tlen);
 896                 MD5_Update(&ctx, (const char *)&tlen, sizeof(tlen));
 897         } else if (IP_V(ip) == 6) {
 898                 ip6 = (const struct ip6_hdr *)ip;
 899                 MD5_Update(&ctx, (const char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 900                 MD5_Update(&ctx, (const char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 901                 len32 = htonl(GET_BE_U_2(ip6->ip6_plen));
 902                 MD5_Update(&ctx, (const char *)&len32, sizeof(len32));
 903                 nxt = 0;
 904                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 905                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 906                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 907                 nxt = IPPROTO_TCP;
 908                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 909         } else {
 910                 ND_PRINT("IP version not 4 or 6, ");
 911                 return (CANT_CHECK_SIGNATURE);
 912         }
 913
 914         /*
 915          * Step 2: Update MD5 hash with TCP header, excluding options.
 916          * The TCP checksum must be set to zero.
 917          */
 918         memcpy(&savecsum, tp1.th_sum, sizeof(savecsum));
 919         memset(tp1.th_sum, 0, sizeof(tp1.th_sum));
 920         MD5_Update(&ctx, (const char *)&tp1, sizeof(struct tcphdr));
 921         memcpy(tp1.th_sum, &savecsum, sizeof(tp1.th_sum));
 922         /*
 923          * Step 3: Update MD5 hash with TCP segment data, if present.
 924          */
 925         if (length > 0)
 926                 MD5_Update(&ctx, data, length);
 927         /*
 928          * Step 4: Update MD5 hash with shared secret.
 929          */
 930         MD5_Update(&ctx, ndo->ndo_sigsecret, strlen(ndo->ndo_sigsecret));
 931         MD5_Final(sig, &ctx);
 932
 933         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 934                 return (SIGNATURE_VALID);
 935         else
 936                 return (SIGNATURE_INVALID);
 937 }
 938 USES_APPLE_RST
 939 #endif /* HAVE_LIBCRYPTO */