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 1.70 2000-07-30 05:56:11 assar 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 <ctype.h>
  46 #include <unistd.h>
  47
  48 #ifdef INET6
  49 #include <netinet/ip6.h>
  50 #endif
  51
  52 #include "interface.h"
  53 #include "addrtoname.h"
  54 #include "extract.h"
  55
  56 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  57
  58 #define MAX_RST_DATA_LEN        30
  59
  60 /* Compatibility */
  61 #ifndef TCPOPT_WSCALE
  62 #define TCPOPT_WSCALE           3       /* window scale factor (rfc1072) */
  63 #endif
  64 #ifndef TCPOPT_SACKOK
  65 #define TCPOPT_SACKOK           4       /* selective ack ok (rfc1072) */
  66 #endif
  67 #ifndef TCPOPT_SACK
  68 #define TCPOPT_SACK             5       /* selective ack (rfc1072) */
  69 #endif
  70 #ifndef TCPOPT_ECHO
  71 #define TCPOPT_ECHO             6       /* echo (rfc1072) */
  72 #endif
  73 #ifndef TCPOPT_ECHOREPLY
  74 #define TCPOPT_ECHOREPLY        7       /* echo (rfc1072) */
  75 #endif
  76 #ifndef TCPOPT_TIMESTAMP
  77 #define TCPOPT_TIMESTAMP        8       /* timestamps (rfc1323) */
  78 #endif
  79 #ifndef TCPOPT_CC
  80 #define TCPOPT_CC               11      /* T/TCP CC options (rfc1644) */
  81 #endif
  82 #ifndef TCPOPT_CCNEW
  83 #define TCPOPT_CCNEW            12      /* T/TCP CC options (rfc1644) */
  84 #endif
  85 #ifndef TCPOPT_CCECHO
  86 #define TCPOPT_CCECHO           13      /* T/TCP CC options (rfc1644) */
  87 #endif
  88
  89 /*
  90  * Definitions required for ECN
  91  * for use if the OS running tcpdump does not have ECN
  92  */
  93 #ifndef TH_ECNECHO
  94 #define TH_ECNECHO              0x40    /* ECN Echo in tcp header */
  95 #endif
  96 #ifndef TH_CWR
  97 #define TH_CWR                  0x80    /* ECN Cwnd Reduced in tcp header*/
  98 #endif
  99
 100 struct tha {
 101 #ifndef INET6
 102         struct in_addr src;
 103         struct in_addr dst;
 104 #else
 105         struct in6_addr src;
 106         struct in6_addr dst;
 107 #endif /*INET6*/
 108         u_int port;
 109 };
 110
 111 struct tcp_seq_hash {
 112         struct tcp_seq_hash *nxt;
 113         struct tha addr;
 114         tcp_seq seq;
 115         tcp_seq ack;
 116 };
 117
 118 #define TSEQ_HASHSIZE 919
 119
 120 /* These tcp optinos do not have the size octet */
 121 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
 122
 123 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
 124
 125
 126 #ifndef TELNET_PORT
 127 #define TELNET_PORT     23
 128 #endif
 129 #ifndef BGP_PORT
 130 #define BGP_PORT        179
 131 #endif
 132 #define NETBIOS_SSN_PORT 139
 133 #ifndef NFS_PORT
 134 #define NFS_PORT        2049
 135 #endif
 136
 137 void
 138 tcp_print(register const u_char *bp, register u_int length,
 139           register const u_char *bp2)
 140 {
 141         register const struct tcphdr *tp;
 142         register const struct ip *ip;
 143         register u_char flags;
 144         register int hlen;
 145         register char ch;
 146         u_int16_t sport, dport, win, urp;
 147         u_int32_t seq, ack, thseq, thack;
 148         int threv;
 149 #ifdef INET6
 150         register const struct ip6_hdr *ip6;
 151 #endif
 152
 153         tp = (struct tcphdr *)bp;
 154         ip = (struct ip *)bp2;
 155 #ifdef INET6
 156         if (ip->ip_v == 6)
 157                 ip6 = (struct ip6_hdr *)bp2;
 158         else
 159                 ip6 = NULL;
 160 #endif /*INET6*/
 161         ch = '\0';
 162         if (!TTEST(tp->th_dport)) {
 163                 (void)printf("%s > %s: [|tcp]",
 164                         ipaddr_string(&ip->ip_src),
 165                         ipaddr_string(&ip->ip_dst));
 166                 return;
 167         }
 168
 169         sport = ntohs(tp->th_sport);
 170         dport = ntohs(tp->th_dport);
 171
 172
 173         hlen = tp->th_off * 4;
 174
 175         /*
 176          * If data present and NFS port used, assume NFS.
 177          * Pass offset of data plus 4 bytes for RPC TCP msg length
 178          * to NFS print routines.
 179          */
 180         if (!qflag) {
 181                 if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
 182                     dport == NFS_PORT) {
 183                         nfsreq_print((u_char *)tp + hlen + 4, length-hlen,
 184                                      (u_char *)ip);
 185                         return;
 186                 } else if ((u_char *)tp + 4 + sizeof(struct rpc_msg)
 187                            <= snapend &&
 188                            sport == NFS_PORT) {
 189                         nfsreply_print((u_char *)tp + hlen + 4,length-hlen,
 190                                        (u_char *)ip);
 191                         return;
 192                 }
 193         }
 194 #ifdef INET6
 195         if (ip6) {
 196                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 197                         (void)printf("%s.%s > %s.%s: ",
 198                                 ip6addr_string(&ip6->ip6_src),
 199                                 tcpport_string(sport),
 200                                 ip6addr_string(&ip6->ip6_dst),
 201                                 tcpport_string(dport));
 202                 } else {
 203                         (void)printf("%s > %s: ",
 204                                 tcpport_string(sport), tcpport_string(dport));
 205                 }
 206         } else
 207 #endif /*INET6*/
 208         {
 209                 if (ip->ip_p == IPPROTO_TCP) {
 210                         (void)printf("%s.%s > %s.%s: ",
 211                                 ipaddr_string(&ip->ip_src),
 212                                 tcpport_string(sport),
 213                                 ipaddr_string(&ip->ip_dst),
 214                                 tcpport_string(dport));
 215                 } else {
 216                         (void)printf("%s > %s: ",
 217                                 tcpport_string(sport), tcpport_string(dport));
 218                 }
 219         }
 220
 221         TCHECK(*tp);
 222
 223         seq = (u_int32_t)ntohl(tp->th_seq);
 224         ack = (u_int32_t)ntohl(tp->th_ack);
 225         win = ntohs(tp->th_win);
 226         urp = ntohs(tp->th_urp);
 227
 228         if (qflag) {
 229                 (void)printf("tcp %d", length - tp->th_off * 4);
 230                 return;
 231         }
 232         if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
 233                                       TH_ECNECHO|TH_CWR)) {
 234                 if (flags & TH_SYN)
 235                         putchar('S');
 236                 if (flags & TH_FIN)
 237                         putchar('F');
 238                 if (flags & TH_RST)
 239                         putchar('R');
 240                 if (flags & TH_PUSH)
 241                         putchar('P');
 242                 if (flags & TH_CWR)
 243                         putchar('W');   /* congestion _W_indow reduced (ECN) */
 244                 if (flags & TH_ECNECHO)
 245                         putchar('E');   /* ecn _E_cho sent (ECN) */
 246         } else
 247                 putchar('.');
 248
 249         if (!Sflag && (flags & TH_ACK)) {
 250                 register struct tcp_seq_hash *th;
 251                 register int rev;
 252                 struct tha tha;
 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 #ifdef INET6
 260                 memset(&tha, 0, sizeof(tha));
 261                 rev = 0;
 262                 if (ip6) {
 263                         if (sport > dport) {
 264                                 rev = 1;
 265                         } else if (sport == dport) {
 266                             int i;
 267
 268                             for (i = 0; i < 4; i++) {
 269                                 if (((u_int32_t *)(&ip6->ip6_src))[i] >
 270                                     ((u_int32_t *)(&ip6->ip6_dst))[i]) {
 271                                         rev = 1;
 272                                         break;
 273                                 }
 274                             }
 275                         }
 276                         if (rev) {
 277                                 tha.src = ip6->ip6_dst;
 278                                 tha.dst = ip6->ip6_src;
 279                                 tha.port = dport << 16 | sport;
 280                         } else {
 281                                 tha.dst = ip6->ip6_dst;
 282                                 tha.src = ip6->ip6_src;
 283                                 tha.port = sport << 16 | dport;
 284                         }
 285                 } else {
 286                         if (sport > dport ||
 287                             (sport == dport &&
 288                              ip->ip_src.s_addr > ip->ip_dst.s_addr)) {
 289                                 rev = 1;
 290                         }
 291                         if (rev) {
 292                                 *(struct in_addr *)&tha.src = ip->ip_dst;
 293                                 *(struct in_addr *)&tha.dst = ip->ip_src;
 294                                 tha.port = dport << 16 | sport;
 295                         } else {
 296                                 *(struct in_addr *)&tha.dst = ip->ip_dst;
 297                                 *(struct in_addr *)&tha.src = ip->ip_src;
 298                                 tha.port = sport << 16 | dport;
 299                         }
 300                 }
 301 #else
 302                 if (sport < dport ||
 303                     (sport == dport &&
 304                      ip->ip_src.s_addr < ip->ip_dst.s_addr)) {
 305                         tha.src = ip->ip_src, tha.dst = ip->ip_dst;
 306                         tha.port = sport << 16 | dport;
 307                         rev = 0;
 308                 } else {
 309                         tha.src = ip->ip_dst, tha.dst = ip->ip_src;
 310                         tha.port = dport << 16 | sport;
 311                         rev = 1;
 312                 }
 313 #endif
 314
 315                 threv = rev;
 316                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 317                      th->nxt; th = th->nxt)
 318                         if (!memcmp((char *)&tha, (char *)&th->addr,
 319                                   sizeof(th->addr)))
 320                                 break;
 321
 322                 if (!th->nxt || (flags & TH_SYN)) {
 323                         /* didn't find it or new conversation */
 324                         if (th->nxt == NULL) {
 325                                 th->nxt = (struct tcp_seq_hash *)
 326                                         calloc(1, sizeof(*th));
 327                                 if (th->nxt == NULL)
 328                                         error("tcp_print: calloc");
 329                         }
 330                         th->addr = tha;
 331                         if (rev)
 332                                 th->ack = seq, th->seq = ack - 1;
 333                         else
 334                                 th->seq = seq, th->ack = ack - 1;
 335
 336                 } else {
 337                         if (rev)
 338                                 seq -= th->ack, ack -= th->seq;
 339                         else
 340                                 seq -= th->seq, ack -= th->ack;
 341                 }
 342
 343                 thseq = th->seq;
 344                 thack = th->ack;
 345         } else {
 346                 /*fool gcc*/
 347                 thseq = thack = threv = 0;
 348         }
 349         if (hlen > length) {
 350                 (void)printf(" [bad hdr length]");
 351                 return;
 352         }
 353         length -= hlen;
 354         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
 355                 (void)printf(" %u:%u(%d)", seq, seq + length, length);
 356         if (flags & TH_ACK)
 357                 (void)printf(" ack %u", ack);
 358
 359         (void)printf(" win %d", win);
 360
 361         if (flags & TH_URG)
 362                 (void)printf(" urg %d", urp);
 363         /*
 364          * Handle any options.
 365          */
 366         if ((hlen -= sizeof(*tp)) > 0) {
 367                 register const u_char *cp;
 368                 register int i, opt, len, datalen;
 369
 370                 cp = (const u_char *)tp + sizeof(*tp);
 371                 putchar(' ');
 372                 ch = '<';
 373                 while (hlen > 0) {
 374                         putchar(ch);
 375                         TCHECK(*cp);
 376                         opt = *cp++;
 377                         if (ZEROLENOPT(opt))
 378                                 len = 1;
 379                         else {
 380                                 TCHECK(*cp);
 381                                 len = *cp++;    /* total including type, len */
 382                                 if (len < 2 || len > hlen)
 383                                         goto bad;
 384                                 --hlen;         /* account for length byte */
 385                         }
 386                         --hlen;                 /* account for type byte */
 387                         datalen = 0;
 388
 389 /* Bail if "l" bytes of data are not left or were not captured  */
 390 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 391
 392                         switch (opt) {
 393
 394                         case TCPOPT_MAXSEG:
 395                                 (void)printf("mss");
 396                                 datalen = 2;
 397                                 LENCHECK(datalen);
 398                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 399
 400                                 break;
 401
 402                         case TCPOPT_EOL:
 403                                 (void)printf("eol");
 404                                 break;
 405
 406                         case TCPOPT_NOP:
 407                                 (void)printf("nop");
 408                                 break;
 409
 410                         case TCPOPT_WSCALE:
 411                                 (void)printf("wscale");
 412                                 datalen = 1;
 413                                 LENCHECK(datalen);
 414                                 (void)printf(" %u", *cp);
 415                                 break;
 416
 417                         case TCPOPT_SACKOK:
 418                                 (void)printf("sackOK");
 419                                 break;
 420
 421                         case TCPOPT_SACK:
 422                                 (void)printf("sack");
 423                                 datalen = len - 2;
 424                                 if (datalen % 8 != 0) {
 425                                         (void)printf(" malformed sack ");
 426                                 } else {
 427                                         u_int32_t s, e;
 428
 429                                         (void)printf(" sack %d ", datalen / 8);
 430                                         for (i = 0; i < datalen; i += 8) {
 431                                                 LENCHECK(i + 4);
 432                                                 s = EXTRACT_32BITS(cp + i);
 433                                                 LENCHECK(i + 8);
 434                                                 e = EXTRACT_32BITS(cp + i + 4);
 435                                                 if (threv) {
 436                                                         s -= thseq;
 437                                                         e -= thseq;
 438                                                 } else {
 439                                                         s -= thack;
 440                                                         e -= thack;
 441                                                 }
 442                                                 (void)printf("{%u:%u}", s, e);
 443                                         }
 444                                         (void)printf(" ");
 445                                 }
 446                                 break;
 447
 448                         case TCPOPT_ECHO:
 449                                 (void)printf("echo");
 450                                 datalen = 4;
 451                                 LENCHECK(datalen);
 452                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 453                                 break;
 454
 455                         case TCPOPT_ECHOREPLY:
 456                                 (void)printf("echoreply");
 457                                 datalen = 4;
 458                                 LENCHECK(datalen);
 459                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 460                                 break;
 461
 462                         case TCPOPT_TIMESTAMP:
 463                                 (void)printf("timestamp");
 464                                 datalen = 8;
 465                                 LENCHECK(4);
 466                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 467                                 LENCHECK(datalen);
 468                                 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
 469                                 break;
 470
 471                         case TCPOPT_CC:
 472                                 (void)printf("cc");
 473                                 datalen = 4;
 474                                 LENCHECK(datalen);
 475                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 476                                 break;
 477
 478                         case TCPOPT_CCNEW:
 479                                 (void)printf("ccnew");
 480                                 datalen = 4;
 481                                 LENCHECK(datalen);
 482                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 483                                 break;
 484
 485                         case TCPOPT_CCECHO:
 486                                 (void)printf("ccecho");
 487                                 datalen = 4;
 488                                 LENCHECK(datalen);
 489                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 490                                 break;
 491
 492                         default:
 493                                 (void)printf("opt-%d:", opt);
 494                                 datalen = len - 2;
 495                                 for (i = 0; i < datalen; ++i) {
 496                                         LENCHECK(i);
 497                                         (void)printf("%02x", cp[i]);
 498                                 }
 499                                 break;
 500                         }
 501
 502                         /* Account for data printed */
 503                         cp += datalen;
 504                         hlen -= datalen;
 505
 506                         /* Check specification against observed length */
 507                         ++datalen;                      /* option octet */
 508                         if (!ZEROLENOPT(opt))
 509                                 ++datalen;              /* size octet */
 510                         if (datalen != len)
 511                                 (void)printf("[len %d]", len);
 512                         ch = ',';
 513                         if (opt == TCPOPT_EOL)
 514                                 break;
 515                 }
 516                 putchar('>');
 517         }
 518
 519         if (length <= 0)
 520                 return;
 521
 522         /*
 523          * Decode payload if necessary.
 524          */
 525         bp += (tp->th_off * 4);
 526         if (flags & TH_RST) {
 527                 if (vflag)
 528                         print_tcp_rst_data(bp, length);
 529         } else {
 530                 if (sport == TELNET_PORT || dport == TELNET_PORT) {
 531                         if (!qflag && vflag)
 532                                 telnet_print(bp, length);
 533                 } else if (sport == BGP_PORT || dport == BGP_PORT)
 534                         bgp_print(bp, length);
 535                 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 536                         nbt_tcp_print(bp, length);
 537         }
 538         return;
 539 bad:
 540         fputs("[bad opt]", stdout);
 541         if (ch != '\0')
 542                 putchar('>');
 543         return;
 544 trunc:
 545         fputs("[|tcp]", stdout);
 546         if (ch != '\0')
 547                 putchar('>');
 548 }
 549
 550 /*
 551  * RFC1122 says the following on data in RST segments:
 552  *
 553  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 554  *
 555  *            A TCP SHOULD allow a received RST segment to include data.
 556  *
 557  *            DISCUSSION
 558  *                 It has been suggested that a RST segment could contain
 559  *                 ASCII text that encoded and explained the cause of the
 560  *                 RST.  No standard has yet been established for such
 561  *                 data.
 562  *
 563  */
 564
 565 static void
 566 print_tcp_rst_data(register const u_char *sp, u_int length)
 567 {
 568         int c;
 569
 570         if (TTEST2(*sp, length))
 571                 printf(" [RST");
 572         else
 573                 printf(" [!RST");
 574         if (length > MAX_RST_DATA_LEN) {
 575                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 576                 putchar('+');                   /* indicate we truncate */
 577         }
 578         putchar(' ');
 579         while (length-- && sp <= snapend) {
 580                 c = *sp++;
 581                 if (isprint(c))
 582                         putchar(c);
 583                 else
 584                         putchar('.');
 585         }
 586         putchar(']');
 587 }