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  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 #ifndef lint
  23 static const char rcsid[] =
  24     "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.69 2000-07-29 09:06:23 guy Exp $ (LBL)";
  25 #endif
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <sys/param.h>
  32 #include <sys/time.h>
  33
  34 #include <rpc/rpc.h>
  35
  36 #include <netinet/in.h>
  37 #include <netinet/in_systm.h>
  38 #include <netinet/ip.h>
  39 #include <netinet/ip_var.h>
  40 #include <netinet/tcp.h>
  41
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <unistd.h>
  46
  47 #ifdef INET6
  48 #include <netinet/ip6.h>
  49 #endif
  50
  51 #include "interface.h"
  52 #include "addrtoname.h"
  53 #include "extract.h"
  54
  55 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  56
  57 #define MAX_RST_DATA_LEN        30
  58
  59 /* Compatibility */
  60 #ifndef TCPOPT_WSCALE
  61 #define TCPOPT_WSCALE           3       /* window scale factor (rfc1072) */
  62 #endif
  63 #ifndef TCPOPT_SACKOK
  64 #define TCPOPT_SACKOK           4       /* selective ack ok (rfc1072) */
  65 #endif
  66 #ifndef TCPOPT_SACK
  67 #define TCPOPT_SACK             5       /* selective ack (rfc1072) */
  68 #endif
  69 #ifndef TCPOPT_ECHO
  70 #define TCPOPT_ECHO             6       /* echo (rfc1072) */
  71 #endif
  72 #ifndef TCPOPT_ECHOREPLY
  73 #define TCPOPT_ECHOREPLY        7       /* echo (rfc1072) */
  74 #endif
  75 #ifndef TCPOPT_TIMESTAMP
  76 #define TCPOPT_TIMESTAMP        8       /* timestamps (rfc1323) */
  77 #endif
  78 #ifndef TCPOPT_CC
  79 #define TCPOPT_CC               11      /* T/TCP CC options (rfc1644) */
  80 #endif
  81 #ifndef TCPOPT_CCNEW
  82 #define TCPOPT_CCNEW            12      /* T/TCP CC options (rfc1644) */
  83 #endif
  84 #ifndef TCPOPT_CCECHO
  85 #define TCPOPT_CCECHO           13      /* T/TCP CC options (rfc1644) */
  86 #endif
  87
  88 /*
  89  * Definitions required for ECN
  90  * for use if the OS running tcpdump does not have ECN
  91  */
  92 #ifndef TH_ECNECHO
  93 #define TH_ECNECHO              0x40    /* ECN Echo in tcp header */
  94 #endif
  95 #ifndef TH_CWR
  96 #define TH_CWR                  0x80    /* ECN Cwnd Reduced in tcp header*/
  97 #endif
  98
  99 struct tha {
 100 #ifndef INET6
 101         struct in_addr src;
 102         struct in_addr dst;
 103 #else
 104         struct in6_addr src;
 105         struct in6_addr dst;
 106 #endif /*INET6*/
 107         u_int port;
 108 };
 109
 110 struct tcp_seq_hash {
 111         struct tcp_seq_hash *nxt;
 112         struct tha addr;
 113         tcp_seq seq;
 114         tcp_seq ack;
 115 };
 116
 117 #define TSEQ_HASHSIZE 919
 118
 119 /* These tcp optinos do not have the size octet */
 120 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
 121
 122 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
 123
 124
 125 #ifndef TELNET_PORT
 126 #define TELNET_PORT     23
 127 #endif
 128 #ifndef BGP_PORT
 129 #define BGP_PORT        179
 130 #endif
 131 #define NETBIOS_SSN_PORT 139
 132 #ifndef NFS_PORT
 133 #define NFS_PORT        2049
 134 #endif
 135
 136 void
 137 tcp_print(register const u_char *bp, register u_int length,
 138           register const u_char *bp2)
 139 {
 140         register const struct tcphdr *tp;
 141         register const struct ip *ip;
 142         register u_char flags;
 143         register int hlen;
 144         register char ch;
 145         u_int16_t sport, dport, win, urp;
 146         u_int32_t seq, ack, thseq, thack;
 147         int threv;
 148 #ifdef INET6
 149         register const struct ip6_hdr *ip6;
 150 #endif
 151
 152         tp = (struct tcphdr *)bp;
 153         ip = (struct ip *)bp2;
 154 #ifdef INET6
 155         if (ip->ip_v == 6)
 156                 ip6 = (struct ip6_hdr *)bp2;
 157         else
 158                 ip6 = NULL;
 159 #endif /*INET6*/
 160         ch = '\0';
 161         if (!TTEST(tp->th_dport)) {
 162                 (void)printf("%s > %s: [|tcp]",
 163                         ipaddr_string(&ip->ip_src),
 164                         ipaddr_string(&ip->ip_dst));
 165                 return;
 166         }
 167
 168         sport = ntohs(tp->th_sport);
 169         dport = ntohs(tp->th_dport);
 170
 171
 172         hlen = tp->th_off * 4;
 173
 174         /*
 175          * If data present and NFS port used, assume NFS.
 176          * Pass offset of data plus 4 bytes for RPC TCP msg length
 177          * to NFS print routines.
 178          */
 179         if (!qflag) {
 180                 if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
 181                     dport == NFS_PORT) {
 182                         nfsreq_print((u_char *)tp + hlen + 4, length-hlen,
 183                                      (u_char *)ip);
 184                         return;
 185                 } else if ((u_char *)tp + 4 + sizeof(struct rpc_msg)
 186                            <= snapend &&
 187                            sport == NFS_PORT) {
 188                         nfsreply_print((u_char *)tp + hlen + 4,length-hlen,
 189                                        (u_char *)ip);
 190                         return;
 191                 }
 192         }
 193 #ifdef INET6
 194         if (ip6) {
 195                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 196                         (void)printf("%s.%s > %s.%s: ",
 197                                 ip6addr_string(&ip6->ip6_src),
 198                                 tcpport_string(sport),
 199                                 ip6addr_string(&ip6->ip6_dst),
 200                                 tcpport_string(dport));
 201                 } else {
 202                         (void)printf("%s > %s: ",
 203                                 tcpport_string(sport), tcpport_string(dport));
 204                 }
 205         } else
 206 #endif /*INET6*/
 207         {
 208                 if (ip->ip_p == IPPROTO_TCP) {
 209                         (void)printf("%s.%s > %s.%s: ",
 210                                 ipaddr_string(&ip->ip_src),
 211                                 tcpport_string(sport),
 212                                 ipaddr_string(&ip->ip_dst),
 213                                 tcpport_string(dport));
 214                 } else {
 215                         (void)printf("%s > %s: ",
 216                                 tcpport_string(sport), tcpport_string(dport));
 217                 }
 218         }
 219
 220         TCHECK(*tp);
 221
 222         seq = (u_int32_t)ntohl(tp->th_seq);
 223         ack = (u_int32_t)ntohl(tp->th_ack);
 224         win = ntohs(tp->th_win);
 225         urp = ntohs(tp->th_urp);
 226
 227         if (qflag) {
 228                 (void)printf("tcp %d", length - tp->th_off * 4);
 229                 return;
 230         }
 231         if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
 232                                       TH_ECNECHO|TH_CWR)) {
 233                 if (flags & TH_SYN)
 234                         putchar('S');
 235                 if (flags & TH_FIN)
 236                         putchar('F');
 237                 if (flags & TH_RST)
 238                         putchar('R');
 239                 if (flags & TH_PUSH)
 240                         putchar('P');
 241                 if (flags & TH_CWR)
 242                         putchar('W');   /* congestion _W_indow reduced (ECN) */
 243                 if (flags & TH_ECNECHO)
 244                         putchar('E');   /* ecn _E_cho sent (ECN) */
 245         } else
 246                 putchar('.');
 247
 248         if (!Sflag && (flags & TH_ACK)) {
 249                 register struct tcp_seq_hash *th;
 250                 register int rev;
 251                 struct tha tha;
 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 #ifdef INET6
 259                 memset(&tha, 0, sizeof(tha));
 260                 rev = 0;
 261                 if (ip6) {
 262                         if (sport > dport) {
 263                                 rev = 1;
 264                         } else if (sport == dport) {
 265                             int i;
 266
 267                             for (i = 0; i < 4; i++) {
 268                                 if (((u_int32_t *)(&ip6->ip6_src))[i] >
 269                                     ((u_int32_t *)(&ip6->ip6_dst))[i]) {
 270                                         rev = 1;
 271                                         break;
 272                                 }
 273                             }
 274                         }
 275                         if (rev) {
 276                                 tha.src = ip6->ip6_dst;
 277                                 tha.dst = ip6->ip6_src;
 278                                 tha.port = dport << 16 | sport;
 279                         } else {
 280                                 tha.dst = ip6->ip6_dst;
 281                                 tha.src = ip6->ip6_src;
 282                                 tha.port = sport << 16 | dport;
 283                         }
 284                 } else {
 285                         if (sport > dport ||
 286                             (sport == dport &&
 287                              ip->ip_src.s_addr > ip->ip_dst.s_addr)) {
 288                                 rev = 1;
 289                         }
 290                         if (rev) {
 291                                 *(struct in_addr *)&tha.src = ip->ip_dst;
 292                                 *(struct in_addr *)&tha.dst = ip->ip_src;
 293                                 tha.port = dport << 16 | sport;
 294                         } else {
 295                                 *(struct in_addr *)&tha.dst = ip->ip_dst;
 296                                 *(struct in_addr *)&tha.src = ip->ip_src;
 297                                 tha.port = sport << 16 | dport;
 298                         }
 299                 }
 300 #else
 301                 if (sport < dport ||
 302                     (sport == dport &&
 303                      ip->ip_src.s_addr < ip->ip_dst.s_addr)) {
 304                         tha.src = ip->ip_src, tha.dst = ip->ip_dst;
 305                         tha.port = sport << 16 | dport;
 306                         rev = 0;
 307                 } else {
 308                         tha.src = ip->ip_dst, tha.dst = ip->ip_src;
 309                         tha.port = dport << 16 | sport;
 310                         rev = 1;
 311                 }
 312 #endif
 313
 314                 threv = rev;
 315                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 316                      th->nxt; th = th->nxt)
 317                         if (!memcmp((char *)&tha, (char *)&th->addr,
 318                                   sizeof(th->addr)))
 319                                 break;
 320
 321                 if (!th->nxt || (flags & TH_SYN)) {
 322                         /* didn't find it or new conversation */
 323                         if (th->nxt == NULL) {
 324                                 th->nxt = (struct tcp_seq_hash *)
 325                                         calloc(1, sizeof(*th));
 326                                 if (th->nxt == NULL)
 327                                         error("tcp_print: calloc");
 328                         }
 329                         th->addr = tha;
 330                         if (rev)
 331                                 th->ack = seq, th->seq = ack - 1;
 332                         else
 333                                 th->seq = seq, th->ack = ack - 1;
 334
 335                 } else {
 336                         if (rev)
 337                                 seq -= th->ack, ack -= th->seq;
 338                         else
 339                                 seq -= th->seq, ack -= th->ack;
 340                 }
 341
 342                 thseq = th->seq;
 343                 thack = th->ack;
 344         } else {
 345                 /*fool gcc*/
 346                 thseq = thack = threv = 0;
 347         }
 348         if (hlen > length) {
 349                 (void)printf(" [bad hdr length]");
 350                 return;
 351         }
 352         length -= hlen;
 353         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
 354                 (void)printf(" %u:%u(%d)", seq, seq + length, length);
 355         if (flags & TH_ACK)
 356                 (void)printf(" ack %u", ack);
 357
 358         (void)printf(" win %d", win);
 359
 360         if (flags & TH_URG)
 361                 (void)printf(" urg %d", urp);
 362         /*
 363          * Handle any options.
 364          */
 365         if ((hlen -= sizeof(*tp)) > 0) {
 366                 register const u_char *cp;
 367                 register int i, opt, len, datalen;
 368
 369                 cp = (const u_char *)tp + sizeof(*tp);
 370                 putchar(' ');
 371                 ch = '<';
 372                 while (hlen > 0) {
 373                         putchar(ch);
 374                         TCHECK(*cp);
 375                         opt = *cp++;
 376                         if (ZEROLENOPT(opt))
 377                                 len = 1;
 378                         else {
 379                                 TCHECK(*cp);
 380                                 len = *cp++;    /* total including type, len */
 381                                 if (len < 2 || len > hlen)
 382                                         goto bad;
 383                                 --hlen;         /* account for length byte */
 384                         }
 385                         --hlen;                 /* account for type byte */
 386                         datalen = 0;
 387
 388 /* Bail if "l" bytes of data are not left or were not captured  */
 389 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 390
 391                         switch (opt) {
 392
 393                         case TCPOPT_MAXSEG:
 394                                 (void)printf("mss");
 395                                 datalen = 2;
 396                                 LENCHECK(datalen);
 397                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 398
 399                                 break;
 400
 401                         case TCPOPT_EOL:
 402                                 (void)printf("eol");
 403                                 break;
 404
 405                         case TCPOPT_NOP:
 406                                 (void)printf("nop");
 407                                 break;
 408
 409                         case TCPOPT_WSCALE:
 410                                 (void)printf("wscale");
 411                                 datalen = 1;
 412                                 LENCHECK(datalen);
 413                                 (void)printf(" %u", *cp);
 414                                 break;
 415
 416                         case TCPOPT_SACKOK:
 417                                 (void)printf("sackOK");
 418                                 break;
 419
 420                         case TCPOPT_SACK:
 421                                 (void)printf("sack");
 422                                 datalen = len - 2;
 423                                 if (datalen % 8 != 0) {
 424                                         (void)printf(" malformed sack ");
 425                                 } else {
 426                                         u_int32_t s, e;
 427
 428                                         (void)printf(" sack %d ", datalen / 8);
 429                                         for (i = 0; i < datalen; i += 8) {
 430                                                 LENCHECK(i + 4);
 431                                                 s = EXTRACT_32BITS(cp + i);
 432                                                 LENCHECK(i + 8);
 433                                                 e = EXTRACT_32BITS(cp + i + 4);
 434                                                 if (threv) {
 435                                                         s -= thseq;
 436                                                         e -= thseq;
 437                                                 } else {
 438                                                         s -= thack;
 439                                                         e -= thack;
 440                                                 }
 441                                                 (void)printf("{%u:%u}", s, e);
 442                                         }
 443                                         (void)printf(" ");
 444                                 }
 445                                 break;
 446
 447                         case TCPOPT_ECHO:
 448                                 (void)printf("echo");
 449                                 datalen = 4;
 450                                 LENCHECK(datalen);
 451                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 452                                 break;
 453
 454                         case TCPOPT_ECHOREPLY:
 455                                 (void)printf("echoreply");
 456                                 datalen = 4;
 457                                 LENCHECK(datalen);
 458                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 459                                 break;
 460
 461                         case TCPOPT_TIMESTAMP:
 462                                 (void)printf("timestamp");
 463                                 datalen = 8;
 464                                 LENCHECK(4);
 465                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 466                                 LENCHECK(datalen);
 467                                 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
 468                                 break;
 469
 470                         case TCPOPT_CC:
 471                                 (void)printf("cc");
 472                                 datalen = 4;
 473                                 LENCHECK(datalen);
 474                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 475                                 break;
 476
 477                         case TCPOPT_CCNEW:
 478                                 (void)printf("ccnew");
 479                                 datalen = 4;
 480                                 LENCHECK(datalen);
 481                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 482                                 break;
 483
 484                         case TCPOPT_CCECHO:
 485                                 (void)printf("ccecho");
 486                                 datalen = 4;
 487                                 LENCHECK(datalen);
 488                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 489                                 break;
 490
 491                         default:
 492                                 (void)printf("opt-%d:", opt);
 493                                 datalen = len - 2;
 494                                 for (i = 0; i < datalen; ++i) {
 495                                         LENCHECK(i);
 496                                         (void)printf("%02x", cp[i]);
 497                                 }
 498                                 break;
 499                         }
 500
 501                         /* Account for data printed */
 502                         cp += datalen;
 503                         hlen -= datalen;
 504
 505                         /* Check specification against observed length */
 506                         ++datalen;                      /* option octet */
 507                         if (!ZEROLENOPT(opt))
 508                                 ++datalen;              /* size octet */
 509                         if (datalen != len)
 510                                 (void)printf("[len %d]", len);
 511                         ch = ',';
 512                         if (opt == TCPOPT_EOL)
 513                                 break;
 514                 }
 515                 putchar('>');
 516         }
 517
 518         if (length <= 0)
 519                 return;
 520
 521         /*
 522          * Decode payload if necessary.
 523          */
 524         bp += (tp->th_off * 4);
 525         if (flags & TH_RST) {
 526                 if (vflag)
 527                         print_tcp_rst_data(bp, length);
 528         } else {
 529                 if (sport == TELNET_PORT || dport == TELNET_PORT) {
 530                         if (!qflag && vflag)
 531                                 telnet_print(bp, length);
 532                 } else if (sport == BGP_PORT || dport == BGP_PORT)
 533                         bgp_print(bp, length);
 534                 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 535                         nbt_tcp_print(bp, length);
 536         }
 537         return;
 538 bad:
 539         fputs("[bad opt]", stdout);
 540         if (ch != '\0')
 541                 putchar('>');
 542         return;
 543 trunc:
 544         fputs("[|tcp]", stdout);
 545         if (ch != '\0')
 546                 putchar('>');
 547 }
 548
 549 /*
 550  * RFC1122 says the following on data in RST segments:
 551  *
 552  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 553  *
 554  *            A TCP SHOULD allow a received RST segment to include data.
 555  *
 556  *            DISCUSSION
 557  *                 It has been suggested that a RST segment could contain
 558  *                 ASCII text that encoded and explained the cause of the
 559  *                 RST.  No standard has yet been established for such
 560  *                 data.
 561  *
 562  */
 563
 564 static void
 565 print_tcp_rst_data(register const u_char *sp, u_int length)
 566 {
 567         int c;
 568
 569         if (TTEST2(*sp, length))
 570                 printf(" [RST");
 571         else
 572                 printf(" [!RST");
 573         if (length > MAX_RST_DATA_LEN) {
 574                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 575                 putchar('+');                   /* indicate we truncate */
 576         }
 577         putchar(' ');
 578         while (length-- && sp <= snapend) {
 579                 c = *sp++;
 580                 if (isprint(c))
 581                         putchar(c);
 582                 else
 583                         putchar('.');
 584         }
 585         putchar(']');
 586 }