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 #include "netdissect.h"
  43 #include "addrtoname.h"
  44 #include "extract.h"
  45
  46 #include "tcp.h"
  47
  48 #include "ip.h"
  49 #include "ip6.h"
  50 #include "ipproto.h"
  51 #include "rpc_auth.h"
  52 #include "rpc_msg.h"
  53
  54 #ifdef HAVE_LIBCRYPTO
  55 #include <openssl/md5.h>
  56 #include "signature.h"
  57
  58 static int tcp_verify_signature(netdissect_options *ndo,
  59                                 const struct ip *ip, const struct tcphdr *tp,
  60                                 const u_char *data, u_int length, const u_char *rcvsig);
  61 #endif
  62
  63 static void print_tcp_rst_data(netdissect_options *, const u_char *sp, u_int length);
  64 static void print_tcp_fastopen_option(netdissect_options *ndo, const u_char *cp,
  65                                       u_int datalen, int exp);
  66
  67 #define MAX_RST_DATA_LEN        30
  68
  69
  70 struct tha {
  71         nd_ipv4 src;
  72         nd_ipv4 dst;
  73         u_int port;
  74 };
  75
  76 struct tcp_seq_hash {
  77         struct tcp_seq_hash *nxt;
  78         struct tha addr;
  79         uint32_t seq;
  80         uint32_t ack;
  81 };
  82
  83 struct tha6 {
  84         nd_ipv6 src;
  85         nd_ipv6 dst;
  86         u_int port;
  87 };
  88
  89 struct tcp_seq_hash6 {
  90         struct tcp_seq_hash6 *nxt;
  91         struct tha6 addr;
  92         uint32_t seq;
  93         uint32_t ack;
  94 };
  95
  96 #define TSEQ_HASHSIZE 919
  97
  98 /* These tcp options do not have the size octet */
  99 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
 100
 101 static struct tcp_seq_hash tcp_seq_hash4[TSEQ_HASHSIZE];
 102 static struct tcp_seq_hash6 tcp_seq_hash6[TSEQ_HASHSIZE];
 103
 104 static const struct tok tcp_flag_values[] = {
 105         { TH_FIN, "F" },
 106         { TH_SYN, "S" },
 107         { TH_RST, "R" },
 108         { TH_PUSH, "P" },
 109         { TH_ACK, "." },
 110         { TH_URG, "U" },
 111         { TH_ECNECHO, "E" },
 112         { TH_CWR, "W" },
 113         { 0, NULL }
 114 };
 115
 116 static const struct tok tcp_option_values[] = {
 117         { TCPOPT_EOL, "eol" },
 118         { TCPOPT_NOP, "nop" },
 119         { TCPOPT_MAXSEG, "mss" },
 120         { TCPOPT_WSCALE, "wscale" },
 121         { TCPOPT_SACKOK, "sackOK" },
 122         { TCPOPT_SACK, "sack" },
 123         { TCPOPT_ECHO, "echo" },
 124         { TCPOPT_ECHOREPLY, "echoreply" },
 125         { TCPOPT_TIMESTAMP, "TS" },
 126         { TCPOPT_CC, "cc" },
 127         { TCPOPT_CCNEW, "ccnew" },
 128         { TCPOPT_CCECHO, "" },
 129         { TCPOPT_SIGNATURE, "md5" },
 130         { TCPOPT_SCPS, "scps" },
 131         { TCPOPT_UTO, "uto" },
 132         { TCPOPT_TCPAO, "tcp-ao" },
 133         { TCPOPT_MPTCP, "mptcp" },
 134         { TCPOPT_FASTOPEN, "tfo" },
 135         { TCPOPT_EXPERIMENT2, "exp" },
 136         { 0, NULL }
 137 };
 138
 139 static uint16_t
 140 tcp_cksum(netdissect_options *ndo,
 141           const struct ip *ip,
 142           const struct tcphdr *tp,
 143           u_int len)
 144 {
 145         return nextproto4_cksum(ndo, ip, (const uint8_t *)tp, len, len,
 146                                 IPPROTO_TCP);
 147 }
 148
 149 static uint16_t
 150 tcp6_cksum(netdissect_options *ndo,
 151            const struct ip6_hdr *ip6,
 152            const struct tcphdr *tp,
 153            u_int len)
 154 {
 155         return nextproto6_cksum(ndo, ip6, (const uint8_t *)tp, len, len,
 156                                 IPPROTO_TCP);
 157 }
 158
 159 void
 160 tcp_print(netdissect_options *ndo,
 161           const u_char *bp, u_int length,
 162           const u_char *bp2, int fragmented)
 163 {
 164         const struct tcphdr *tp;
 165         const struct ip *ip;
 166         u_char flags;
 167         u_int hlen;
 168         char ch;
 169         uint16_t sport, dport, win, urp;
 170         uint32_t seq, ack, thseq, thack;
 171         u_int utoval;
 172         uint16_t magic;
 173         int rev;
 174         const struct ip6_hdr *ip6;
 175
 176         ndo->ndo_protocol = "tcp";
 177         tp = (const struct tcphdr *)bp;
 178         ip = (const struct ip *)bp2;
 179         if (IP_V(ip) == 6)
 180                 ip6 = (const struct ip6_hdr *)bp2;
 181         else
 182                 ip6 = NULL;
 183         ch = '\0';
 184         if (!ND_TTEST_2(tp->th_dport)) {
 185                 if (ip6) {
 186                         ND_PRINT("%s > %s:",
 187                                  ip6addr_string(ndo, ip6->ip6_src),
 188                                  ip6addr_string(ndo, ip6->ip6_dst));
 189                 } else {
 190                         ND_PRINT("%s > %s:",
 191                                  ipaddr_string(ndo, ip->ip_src),
 192                                  ipaddr_string(ndo, ip->ip_dst));
 193                 }
 194                 nd_print_trunc(ndo);
 195                 return;
 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                                  ip6addr_string(ndo, ip6->ip6_src),
 205                                  tcpport_string(ndo, sport),
 206                                  ip6addr_string(ndo, 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                                  ipaddr_string(ndo, ip->ip_src),
 216                                  tcpport_string(ndo, sport),
 217                                  ipaddr_string(ndo, 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         ND_TCHECK_SIZE(tp);
 226
 227         hlen = TH_OFF(tp) * 4;
 228
 229         if (hlen < sizeof(*tp)) {
 230                 ND_PRINT(" tcp %u [bad hdr length %u - too short, < %zu]",
 231                          length - hlen, hlen, sizeof(*tp));
 232                 return;
 233         }
 234
 235         seq = GET_BE_U_4(tp->th_seq);
 236         ack = GET_BE_U_4(tp->th_ack);
 237         win = GET_BE_U_2(tp->th_win);
 238         urp = GET_BE_U_2(tp->th_urp);
 239
 240         if (ndo->ndo_qflag) {
 241                 ND_PRINT("tcp %u", length - hlen);
 242                 if (hlen > length) {
 243                         ND_PRINT(" [bad hdr length %u - too long, > %u]",
 244                                  hlen, length);
 245                 }
 246                 return;
 247         }
 248
 249         flags = GET_U_1(tp->th_flags);
 250         ND_PRINT("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
 251
 252         if (!ndo->ndo_Sflag && (flags & TH_ACK)) {
 253                 /*
 254                  * Find (or record) the initial sequence numbers for
 255                  * this conversation.  (we pick an arbitrary
 256                  * collating order so there's only one entry for
 257                  * both directions).
 258                  */
 259                 rev = 0;
 260                 if (ip6) {
 261                         struct tcp_seq_hash6 *th;
 262                         struct tcp_seq_hash6 *tcp_seq_hash;
 263                         const void *src, *dst;
 264                         struct tha6 tha;
 265
 266                         tcp_seq_hash = tcp_seq_hash6;
 267                         src = (const void *)ip6->ip6_src;
 268                         dst = (const void *)ip6->ip6_dst;
 269                         if (sport > dport)
 270                                 rev = 1;
 271                         else if (sport == dport) {
 272                                 if (UNALIGNED_MEMCMP(src, dst, sizeof(ip6->ip6_dst)) > 0)
 273                                         rev = 1;
 274                         }
 275                         if (rev) {
 276                                 UNALIGNED_MEMCPY(&tha.src, dst, sizeof(ip6->ip6_dst));
 277                                 UNALIGNED_MEMCPY(&tha.dst, src, sizeof(ip6->ip6_src));
 278                                 tha.port = ((u_int)dport) << 16 | sport;
 279                         } else {
 280                                 UNALIGNED_MEMCPY(&tha.dst, dst, sizeof(ip6->ip6_dst));
 281                                 UNALIGNED_MEMCPY(&tha.src, src, sizeof(ip6->ip6_src));
 282                                 tha.port = ((u_int)sport) << 16 | dport;
 283                         }
 284
 285                         for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 286                              th->nxt; th = th->nxt)
 287                                 if (memcmp((char *)&tha, (char *)&th->addr,
 288                                            sizeof(th->addr)) == 0)
 289                                         break;
 290
 291                         if (!th->nxt || (flags & TH_SYN)) {
 292                                 /* didn't find it or new conversation */
 293                                 /* calloc() return used by the 'tcp_seq_hash6'
 294                                    hash table: do not free() */
 295                                 if (th->nxt == NULL) {
 296                                         th->nxt = (struct tcp_seq_hash6 *)
 297                                                 calloc(1, sizeof(*th));
 298                                         if (th->nxt == NULL)
 299                                                 (*ndo->ndo_error)(ndo,
 300                                                         S_ERR_ND_MEM_ALLOC,
 301                                                         "tcp_print: calloc");
 302                                 }
 303                                 th->addr = tha;
 304                                 if (rev)
 305                                         th->ack = seq, th->seq = ack - 1;
 306                                 else
 307                                         th->seq = seq, th->ack = ack - 1;
 308                         } else {
 309                                 if (rev)
 310                                         seq -= th->ack, ack -= th->seq;
 311                                 else
 312                                         seq -= th->seq, ack -= th->ack;
 313                         }
 314
 315                         thseq = th->seq;
 316                         thack = th->ack;
 317                 } else {
 318                         struct tcp_seq_hash *th;
 319                         struct tcp_seq_hash *tcp_seq_hash;
 320                         struct tha tha;
 321
 322                         tcp_seq_hash = tcp_seq_hash4;
 323                         if (sport > dport)
 324                                 rev = 1;
 325                         else if (sport == dport) {
 326                                 if (UNALIGNED_MEMCMP(ip->ip_src, ip->ip_dst, sizeof(ip->ip_dst)) > 0)
 327                                         rev = 1;
 328                         }
 329                         if (rev) {
 330                                 UNALIGNED_MEMCPY(&tha.src, ip->ip_dst,
 331                                                  sizeof(ip->ip_dst));
 332                                 UNALIGNED_MEMCPY(&tha.dst, ip->ip_src,
 333                                                  sizeof(ip->ip_src));
 334                                 tha.port = ((u_int)dport) << 16 | sport;
 335                         } else {
 336                                 UNALIGNED_MEMCPY(&tha.dst, ip->ip_dst,
 337                                                  sizeof(ip->ip_dst));
 338                                 UNALIGNED_MEMCPY(&tha.src, ip->ip_src,
 339                                                  sizeof(ip->ip_src));
 340                                 tha.port = ((u_int)sport) << 16 | dport;
 341                         }
 342
 343                         for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 344                              th->nxt; th = th->nxt)
 345                                 if (memcmp((char *)&tha, (char *)&th->addr,
 346                                            sizeof(th->addr)) == 0)
 347                                         break;
 348
 349                         if (!th->nxt || (flags & TH_SYN)) {
 350                                 /* didn't find it or new conversation */
 351                                 /* calloc() return used by the 'tcp_seq_hash4'
 352                                    hash table: do not free() */
 353                                 if (th->nxt == NULL) {
 354                                         th->nxt = (struct tcp_seq_hash *)
 355                                                 calloc(1, sizeof(*th));
 356                                         if (th->nxt == NULL)
 357                                                 (*ndo->ndo_error)(ndo,
 358                                                         S_ERR_ND_MEM_ALLOC,
 359                                                         "tcp_print: calloc");
 360                                 }
 361                                 th->addr = tha;
 362                                 if (rev)
 363                                         th->ack = seq, th->seq = ack - 1;
 364                                 else
 365                                         th->seq = seq, th->ack = ack - 1;
 366                         } else {
 367                                 if (rev)
 368                                         seq -= th->ack, ack -= th->seq;
 369                                 else
 370                                         seq -= th->seq, ack -= th->ack;
 371                         }
 372
 373                         thseq = th->seq;
 374                         thack = th->ack;
 375                 }
 376         } else {
 377                 /*fool gcc*/
 378                 thseq = thack = rev = 0;
 379         }
 380         if (hlen > length) {
 381                 ND_PRINT(" [bad hdr length %u - too long, > %u]",
 382                          hlen, length);
 383                 return;
 384         }
 385
 386         if (ndo->ndo_vflag && !ndo->ndo_Kflag && !fragmented) {
 387                 /* Check the checksum, if possible. */
 388                 uint16_t sum, tcp_sum;
 389
 390                 if (IP_V(ip) == 4) {
 391                         if (ND_TTEST_LEN(tp->th_sport, length)) {
 392                                 sum = tcp_cksum(ndo, ip, tp, length);
 393                                 tcp_sum = GET_BE_U_2(tp->th_sum);
 394
 395                                 ND_PRINT(", cksum 0x%04x", tcp_sum);
 396                                 if (sum != 0)
 397                                         ND_PRINT(" (incorrect -> 0x%04x)",
 398                                             in_cksum_shouldbe(tcp_sum, sum));
 399                                 else
 400                                         ND_PRINT(" (correct)");
 401                         }
 402                 } else if (IP_V(ip) == 6) {
 403                         if (ND_TTEST_LEN(tp->th_sport, length)) {
 404                                 sum = tcp6_cksum(ndo, ip6, tp, length);
 405                                 tcp_sum = GET_BE_U_2(tp->th_sum);
 406
 407                                 ND_PRINT(", cksum 0x%04x", tcp_sum);
 408                                 if (sum != 0)
 409                                         ND_PRINT(" (incorrect -> 0x%04x)",
 410                                             in_cksum_shouldbe(tcp_sum, sum));
 411                                 else
 412                                         ND_PRINT(" (correct)");
 413
 414                         }
 415                 }
 416         }
 417
 418         length -= hlen;
 419         if (ndo->ndo_vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
 420                 ND_PRINT(", seq %u", seq);
 421
 422                 if (length > 0) {
 423                         ND_PRINT(":%u", seq + length);
 424                 }
 425         }
 426
 427         if (flags & TH_ACK) {
 428                 ND_PRINT(", ack %u", ack);
 429         }
 430
 431         ND_PRINT(", win %u", win);
 432
 433         if (flags & TH_URG)
 434                 ND_PRINT(", urg %u", urp);
 435         /*
 436          * Handle any options.
 437          */
 438         if (hlen > sizeof(*tp)) {
 439                 const u_char *cp;
 440                 u_int i, opt, datalen;
 441                 u_int len;
 442
 443                 hlen -= sizeof(*tp);
 444                 cp = (const u_char *)tp + sizeof(*tp);
 445                 ND_PRINT(", options [");
 446                 while (hlen > 0) {
 447                         if (ch != '\0')
 448                                 ND_PRINT("%c", ch);
 449                         opt = GET_U_1(cp);
 450                         cp++;
 451                         if (ZEROLENOPT(opt))
 452                                 len = 1;
 453                         else {
 454                                 len = GET_U_1(cp);
 455                                 cp++;   /* total including type, len */
 456                                 if (len < 2 || len > hlen)
 457                                         goto bad;
 458                                 --hlen;         /* account for length byte */
 459                         }
 460                         --hlen;                 /* account for type byte */
 461                         datalen = 0;
 462
 463 /* Bail if "l" bytes of data are not left or were not captured  */
 464 #define LENCHECK(l) { if ((l) > hlen) goto bad; ND_TCHECK_LEN(cp, l); }
 465
 466
 467                         ND_PRINT("%s", tok2str(tcp_option_values, "unknown-%u", opt));
 468
 469                         switch (opt) {
 470
 471                         case TCPOPT_MAXSEG:
 472                                 datalen = 2;
 473                                 LENCHECK(datalen);
 474                                 ND_PRINT(" %u", GET_BE_U_2(cp));
 475                                 break;
 476
 477                         case TCPOPT_WSCALE:
 478                                 datalen = 1;
 479                                 LENCHECK(datalen);
 480                                 ND_PRINT(" %u", GET_U_1(cp));
 481                                 break;
 482
 483                         case TCPOPT_SACK:
 484                                 datalen = len - 2;
 485                                 if (datalen % 8 != 0) {
 486                                         ND_PRINT(" invalid sack");
 487                                 } else {
 488                                         uint32_t s, e;
 489
 490                                         ND_PRINT(" %u ", datalen / 8);
 491                                         for (i = 0; i < datalen; i += 8) {
 492                                                 LENCHECK(i + 4);
 493                                                 s = GET_BE_U_4(cp + i);
 494                                                 LENCHECK(i + 8);
 495                                                 e = GET_BE_U_4(cp + i + 4);
 496                                                 if (rev) {
 497                                                         s -= thseq;
 498                                                         e -= thseq;
 499                                                 } else {
 500                                                         s -= thack;
 501                                                         e -= thack;
 502                                                 }
 503                                                 ND_PRINT("{%u:%u}", s, e);
 504                                         }
 505                                 }
 506                                 break;
 507
 508                         case TCPOPT_CC:
 509                         case TCPOPT_CCNEW:
 510                         case TCPOPT_CCECHO:
 511                         case TCPOPT_ECHO:
 512                         case TCPOPT_ECHOREPLY:
 513
 514                                 /*
 515                                  * those options share their semantics.
 516                                  * fall through
 517                                  */
 518                                 datalen = 4;
 519                                 LENCHECK(datalen);
 520                                 ND_PRINT(" %u", GET_BE_U_4(cp));
 521                                 break;
 522
 523                         case TCPOPT_TIMESTAMP:
 524                                 datalen = 8;
 525                                 LENCHECK(datalen);
 526                                 ND_PRINT(" val %u ecr %u",
 527                                              GET_BE_U_4(cp),
 528                                              GET_BE_U_4(cp + 4));
 529                                 break;
 530
 531                         case TCPOPT_SIGNATURE:
 532                                 datalen = TCP_SIGLEN;
 533                                 LENCHECK(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                                 if (!mptcp_print(ndo, cp-2, len, flags))
 618                                         goto bad;
 619                                 break;
 620
 621                         case TCPOPT_FASTOPEN:
 622                                 datalen = len - 2;
 623                                 LENCHECK(datalen);
 624                                 ND_PRINT(" ");
 625                                 print_tcp_fastopen_option(ndo, cp, datalen, FALSE);
 626                                 break;
 627
 628                         case TCPOPT_EXPERIMENT2:
 629                                 datalen = len - 2;
 630                                 LENCHECK(datalen);
 631                                 if (datalen < 2)
 632                                         goto bad;
 633                                 /* RFC6994 */
 634                                 magic = GET_BE_U_2(cp);
 635                                 ND_PRINT("-");
 636
 637                                 switch(magic) {
 638
 639                                 case 0xf989: /* TCP Fast Open RFC 7413 */
 640                                         print_tcp_fastopen_option(ndo, cp + 2, datalen - 2, TRUE);
 641                                         break;
 642
 643                                 default:
 644                                         /* Unknown magic number */
 645                                         ND_PRINT("%04x", magic);
 646                                         break;
 647                                 }
 648                                 break;
 649
 650                         default:
 651                                 datalen = len - 2;
 652                                 if (datalen)
 653                                         ND_PRINT(" 0x");
 654                                 for (i = 0; i < datalen; ++i) {
 655                                         LENCHECK(i + 1);
 656                                         ND_PRINT("%02x", GET_U_1(cp + i));
 657                                 }
 658                                 break;
 659                         }
 660
 661                         /* Account for data printed */
 662                         cp += datalen;
 663                         hlen -= datalen;
 664
 665                         /* Check specification against observed length */
 666                         ++datalen;              /* option octet */
 667                         if (!ZEROLENOPT(opt))
 668                                 ++datalen;      /* size octet */
 669                         if (datalen != len)
 670                                 ND_PRINT("[len %u]", len);
 671                         ch = ',';
 672                         if (opt == TCPOPT_EOL)
 673                                 break;
 674                 }
 675                 ND_PRINT("]");
 676         }
 677
 678         /*
 679          * Print length field before crawling down the stack.
 680          */
 681         ND_PRINT(", length %u", length);
 682
 683         if (length <= 0)
 684                 return;
 685
 686         /*
 687          * Decode payload if necessary.
 688          */
 689         bp += TH_OFF(tp) * 4;
 690         if ((flags & TH_RST) && ndo->ndo_vflag) {
 691                 print_tcp_rst_data(ndo, bp, length);
 692                 return;
 693         }
 694
 695         if (ndo->ndo_packettype) {
 696                 switch (ndo->ndo_packettype) {
 697                 case PT_ZMTP1:
 698                         zmtp1_print(ndo, bp, length);
 699                         break;
 700                 case PT_RESP:
 701                         resp_print(ndo, bp, length);
 702                         break;
 703                 case PT_DOMAIN:
 704                         /* over_tcp: TRUE, is_mdns: FALSE */
 705                         domain_print(ndo, bp, length, TRUE, FALSE);
 706                         break;
 707                 }
 708                 return;
 709         }
 710
 711         if (IS_SRC_OR_DST_PORT(TELNET_PORT)) {
 712                 telnet_print(ndo, bp, length);
 713         } else if (IS_SRC_OR_DST_PORT(SMTP_PORT)) {
 714                 ND_PRINT(": ");
 715                 smtp_print(ndo, bp, length);
 716         } else if (IS_SRC_OR_DST_PORT(WHOIS_PORT)) {
 717                 ND_PRINT(": ");
 718                 ndo->ndo_protocol = "whois";    /* needed by txtproto_print() */
 719                 txtproto_print(ndo, bp, length, NULL, 0); /* RFC 3912 */
 720         } else if (IS_SRC_OR_DST_PORT(BGP_PORT))
 721                 bgp_print(ndo, bp, length);
 722         else if (IS_SRC_OR_DST_PORT(PPTP_PORT))
 723                 pptp_print(ndo, bp);
 724         else if (IS_SRC_OR_DST_PORT(REDIS_PORT))
 725                 resp_print(ndo, bp, length);
 726         else if (IS_SRC_OR_DST_PORT(SSH_PORT))
 727                 ssh_print(ndo, bp, length);
 728 #ifdef ENABLE_SMB
 729         else if (IS_SRC_OR_DST_PORT(NETBIOS_SSN_PORT))
 730                 nbt_tcp_print(ndo, bp, length);
 731         else if (IS_SRC_OR_DST_PORT(SMB_PORT))
 732                 smb_tcp_print(ndo, bp, length);
 733 #endif
 734         else if (IS_SRC_OR_DST_PORT(BEEP_PORT))
 735                 beep_print(ndo, bp, length);
 736         else if (IS_SRC_OR_DST_PORT(OPENFLOW_PORT_OLD) || IS_SRC_OR_DST_PORT(OPENFLOW_PORT_IANA))
 737                 openflow_print(ndo, bp, length);
 738         else if (IS_SRC_OR_DST_PORT(FTP_PORT)) {
 739                 ND_PRINT(": ");
 740                 ftp_print(ndo, bp, length);
 741         } else if (IS_SRC_OR_DST_PORT(HTTP_PORT) || IS_SRC_OR_DST_PORT(HTTP_PORT_ALT)) {
 742                 ND_PRINT(": ");
 743                 http_print(ndo, bp, length);
 744         } else if (IS_SRC_OR_DST_PORT(RTSP_PORT) || IS_SRC_OR_DST_PORT(RTSP_PORT_ALT)) {
 745                 ND_PRINT(": ");
 746                 rtsp_print(ndo, bp, length);
 747         } else if (IS_SRC_OR_DST_PORT(NAMESERVER_PORT)) {
 748                 /* over_tcp: TRUE, is_mdns: FALSE */
 749                 domain_print(ndo, bp, length, TRUE, FALSE);
 750         } else if (IS_SRC_OR_DST_PORT(MSDP_PORT)) {
 751                 msdp_print(ndo, bp, length);
 752         } else if (IS_SRC_OR_DST_PORT(RPKI_RTR_PORT)) {
 753                 rpki_rtr_print(ndo, bp, length);
 754         } else if (IS_SRC_OR_DST_PORT(LDP_PORT)) {
 755                 ldp_print(ndo, bp, length);
 756         } else if ((IS_SRC_OR_DST_PORT(NFS_PORT)) &&
 757                  length >= 4 && ND_TTEST_4(bp)) {
 758                 /*
 759                  * If data present, header length valid, and NFS port used,
 760                  * assume NFS.
 761                  * Pass offset of data plus 4 bytes for RPC TCP msg length
 762                  * to NFS print routines.
 763                  */
 764                 uint32_t fraglen;
 765                 const struct sunrpc_msg *rp;
 766                 enum sunrpc_msg_type direction;
 767
 768                 fraglen = GET_BE_U_4(bp) & 0x7FFFFFFF;
 769                 if (fraglen > (length) - 4)
 770                         fraglen = (length) - 4;
 771                 rp = (const struct sunrpc_msg *)(bp + 4);
 772                 if (ND_TTEST_4(rp->rm_direction)) {
 773                         direction = (enum sunrpc_msg_type) GET_BE_U_4(rp->rm_direction);
 774                         if (dport == NFS_PORT && direction == SUNRPC_CALL) {
 775                                 ND_PRINT(": NFS request xid %u ",
 776                                          GET_BE_U_4(rp->rm_xid));
 777                                 nfsreq_noaddr_print(ndo, (const u_char *)rp, fraglen, (const u_char *)ip);
 778                                 return;
 779                         }
 780                         if (sport == NFS_PORT && direction == SUNRPC_REPLY) {
 781                                 ND_PRINT(": NFS reply xid %u ",
 782                                          GET_BE_U_4(rp->rm_xid));
 783                                 nfsreply_noaddr_print(ndo, (const u_char *)rp, fraglen, (const u_char *)ip);
 784                                 return;
 785                         }
 786                 }
 787         }
 788
 789         return;
 790 bad:
 791         ND_PRINT("[bad opt]");
 792         if (ch != '\0')
 793                 ND_PRINT("]");
 794         return;
 795 trunc:
 796         nd_print_trunc(ndo);
 797         if (ch != '\0')
 798                 ND_PRINT(">");
 799 }
 800
 801 /*
 802  * RFC1122 says the following on data in RST segments:
 803  *
 804  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 805  *
 806  *            A TCP SHOULD allow a received RST segment to include data.
 807  *
 808  *            DISCUSSION
 809  *                 It has been suggested that a RST segment could contain
 810  *                 ASCII text that encoded and explained the cause of the
 811  *                 RST.  No standard has yet been established for such
 812  *                 data.
 813  *
 814  */
 815
 816 static void
 817 print_tcp_rst_data(netdissect_options *ndo,
 818                    const u_char *sp, u_int length)
 819 {
 820         u_char c;
 821
 822         ND_PRINT(ND_TTEST_LEN(sp, length) ? " [RST" : " [!RST");
 823         if (length > MAX_RST_DATA_LEN) {
 824                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 825                 ND_PRINT("+");                  /* indicate we truncate */
 826         }
 827         ND_PRINT(" ");
 828         while (length && sp < ndo->ndo_snapend) {
 829                 c = GET_U_1(sp);
 830                 sp++;
 831                 fn_print_char(ndo, c);
 832                 length--;
 833         }
 834         ND_PRINT("]");
 835 }
 836
 837 static void
 838 print_tcp_fastopen_option(netdissect_options *ndo, const u_char *cp,
 839                           u_int datalen, int exp)
 840 {
 841         u_int i;
 842
 843         if (exp)
 844                 ND_PRINT("tfo");
 845
 846         if (datalen == 0) {
 847                 /* Fast Open Cookie Request */
 848                 ND_PRINT(" cookiereq");
 849         } else {
 850                 /* Fast Open Cookie */
 851                 if (datalen % 2 != 0 || datalen < 4 || datalen > 16) {
 852                         nd_print_invalid(ndo);
 853                 } else {
 854                         ND_PRINT(" cookie ");
 855                         for (i = 0; i < datalen; ++i)
 856                                 ND_PRINT("%02x", GET_U_1(cp + i));
 857                 }
 858         }
 859 }
 860
 861 #ifdef HAVE_LIBCRYPTO
 862 USES_APPLE_DEPRECATED_API
 863 static int
 864 tcp_verify_signature(netdissect_options *ndo,
 865                      const struct ip *ip, const struct tcphdr *tp,
 866                      const u_char *data, u_int length, const u_char *rcvsig)
 867 {
 868         struct tcphdr tp1;
 869         u_char sig[TCP_SIGLEN];
 870         char zero_proto = 0;
 871         MD5_CTX ctx;
 872         uint16_t savecsum, tlen;
 873         const struct ip6_hdr *ip6;
 874         uint32_t len32;
 875         uint8_t nxt;
 876
 877         if (data + length > ndo->ndo_snapend) {
 878                 ND_PRINT("snaplen too short, ");
 879                 return (CANT_CHECK_SIGNATURE);
 880         }
 881
 882         tp1 = *tp;
 883
 884         if (ndo->ndo_sigsecret == NULL) {
 885                 ND_PRINT("shared secret not supplied with -M, ");
 886                 return (CANT_CHECK_SIGNATURE);
 887         }
 888
 889         MD5_Init(&ctx);
 890         /*
 891          * Step 1: Update MD5 hash with IP pseudo-header.
 892          */
 893         if (IP_V(ip) == 4) {
 894                 MD5_Update(&ctx, (const char *)&ip->ip_src, sizeof(ip->ip_src));
 895                 MD5_Update(&ctx, (const char *)&ip->ip_dst, sizeof(ip->ip_dst));
 896                 MD5_Update(&ctx, (const char *)&zero_proto, sizeof(zero_proto));
 897                 MD5_Update(&ctx, (const char *)&ip->ip_p, sizeof(ip->ip_p));
 898                 tlen = GET_BE_U_2(ip->ip_len) - IP_HL(ip) * 4;
 899                 tlen = htons(tlen);
 900                 MD5_Update(&ctx, (const char *)&tlen, sizeof(tlen));
 901         } else if (IP_V(ip) == 6) {
 902                 ip6 = (const struct ip6_hdr *)ip;
 903                 MD5_Update(&ctx, (const char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
 904                 MD5_Update(&ctx, (const char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
 905                 len32 = htonl(GET_BE_U_2(ip6->ip6_plen));
 906                 MD5_Update(&ctx, (const char *)&len32, sizeof(len32));
 907                 nxt = 0;
 908                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 909                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 910                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 911                 nxt = IPPROTO_TCP;
 912                 MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt));
 913         } else {
 914                 ND_PRINT("IP version not 4 or 6, ");
 915                 return (CANT_CHECK_SIGNATURE);
 916         }
 917
 918         /*
 919          * Step 2: Update MD5 hash with TCP header, excluding options.
 920          * The TCP checksum must be set to zero.
 921          */
 922         memcpy(&savecsum, tp1.th_sum, sizeof(savecsum));
 923         memset(tp1.th_sum, 0, sizeof(tp1.th_sum));
 924         MD5_Update(&ctx, (const char *)&tp1, sizeof(struct tcphdr));
 925         memcpy(tp1.th_sum, &savecsum, sizeof(tp1.th_sum));
 926         /*
 927          * Step 3: Update MD5 hash with TCP segment data, if present.
 928          */
 929         if (length > 0)
 930                 MD5_Update(&ctx, data, length);
 931         /*
 932          * Step 4: Update MD5 hash with shared secret.
 933          */
 934         MD5_Update(&ctx, ndo->ndo_sigsecret, strlen(ndo->ndo_sigsecret));
 935         MD5_Final(sig, &ctx);
 936
 937         if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
 938                 return (SIGNATURE_VALID);
 939         else
 940                 return (SIGNATURE_INVALID);
 941 }
 942 USES_APPLE_RST
 943 #endif /* HAVE_LIBCRYPTO */