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 1.89 2001-09-17 20:06:18 fenner 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
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <ctype.h>
  42 #include <unistd.h>
  43
  44 #include "interface.h"
  45 #include "addrtoname.h"
  46 #include "extract.h"
  47
  48 #include "tcp.h"
  49
  50 #include "ip.h"
  51 #ifdef INET6
  52 #include "ip6.h"
  53 #endif
  54
  55 #include "nameser.h"
  56
  57 static void print_tcp_rst_data(register const u_char *sp, u_int length);
  58
  59 #define MAX_RST_DATA_LEN        30
  60
  61
  62 struct tha {
  63 #ifndef INET6
  64         struct in_addr src;
  65         struct in_addr dst;
  66 #else
  67         struct in6_addr src;
  68         struct in6_addr dst;
  69 #endif /*INET6*/
  70         u_int port;
  71 };
  72
  73 struct tcp_seq_hash {
  74         struct tcp_seq_hash *nxt;
  75         struct tha addr;
  76         tcp_seq seq;
  77         tcp_seq ack;
  78 };
  79
  80 #define TSEQ_HASHSIZE 919
  81
  82 /* These tcp optinos do not have the size octet */
  83 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
  84
  85 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
  86
  87
  88 #ifndef TELNET_PORT
  89 #define TELNET_PORT     23
  90 #endif
  91 #ifndef BGP_PORT
  92 #define BGP_PORT        179
  93 #endif
  94 #define NETBIOS_SSN_PORT 139
  95 #ifndef PPTP_PORT
  96 #define PPTP_PORT       1723
  97 #endif
  98 #define BXXP_PORT        10288
  99 #ifndef NFS_PORT
 100 #define NFS_PORT        2049
 101 #endif
 102 #define MSDP_PORT       639
 103
 104 static int tcp_cksum(register const struct ip *ip,
 105                      register const struct tcphdr *tp,
 106                      register int len)
 107 {
 108         union phu {
 109                 struct phdr {
 110                         u_int32_t src;
 111                         u_int32_t dst;
 112                         u_char mbz;
 113                         u_char proto;
 114                         u_int16_t len;
 115                 } ph;
 116                 u_int16_t pa[6];
 117         } phu;
 118         const u_int16_t *sp;
 119
 120         /* pseudo-header.. */
 121         phu.ph.len = htons(len);        /* XXX */
 122         phu.ph.mbz = 0;
 123         phu.ph.proto = IPPROTO_TCP;
 124         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 125         memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 126
 127         sp = &phu.pa[0];
 128         return in_cksum((u_short *)tp, len,
 129                         sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
 130 }
 131
 132 #ifdef INET6
 133 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 134         int len)
 135 {
 136         int i, tlen;
 137         register const u_int16_t *sp;
 138         u_int32_t sum;
 139         union {
 140                 struct {
 141                         struct in6_addr ph_src;
 142                         struct in6_addr ph_dst;
 143                         u_int32_t       ph_len;
 144                         u_int8_t        ph_zero[3];
 145                         u_int8_t        ph_nxt;
 146                 } ph;
 147                 u_int16_t pa[20];
 148         } phu;
 149
 150         tlen = ntohs(ip6->ip6_plen) + sizeof(struct ip6_hdr) -
 151             ((const char *)tp - (const char*)ip6);
 152
 153         /* pseudo-header */
 154         memset(&phu, 0, sizeof(phu));
 155         phu.ph.ph_src = ip6->ip6_src;
 156         phu.ph.ph_dst = ip6->ip6_dst;
 157         phu.ph.ph_len = htonl(tlen);
 158         phu.ph.ph_nxt = IPPROTO_TCP;
 159
 160         sum = 0;
 161         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 162                 sum += phu.pa[i];
 163
 164         sp = (const u_int16_t *)tp;
 165
 166         for (i = 0; i < (tlen & ~1); i += 2)
 167                 sum += *sp++;
 168
 169         if (tlen & 1)
 170                 sum += htons((*(const u_int8_t *)sp) << 8);
 171
 172         while (sum > 0xffff)
 173                 sum = (sum & 0xffff) + (sum >> 16);
 174         sum = ~sum & 0xffff;
 175
 176         return (sum);
 177 }
 178 #endif
 179
 180 void
 181 tcp_print(register const u_char *bp, register u_int length,
 182           register const u_char *bp2, int fragmented)
 183 {
 184         register const struct tcphdr *tp;
 185         register const struct ip *ip;
 186         register u_char flags;
 187         register int hlen;
 188         register char ch;
 189         u_int16_t sport, dport, win, urp;
 190         u_int32_t seq, ack, thseq, thack;
 191         int threv;
 192 #ifdef INET6
 193         register const struct ip6_hdr *ip6;
 194 #endif
 195
 196         tp = (struct tcphdr *)bp;
 197         ip = (struct ip *)bp2;
 198 #ifdef INET6
 199         if (IP_V(ip) == 6)
 200                 ip6 = (struct ip6_hdr *)bp2;
 201         else
 202                 ip6 = NULL;
 203 #endif /*INET6*/
 204         ch = '\0';
 205         if (!TTEST(tp->th_dport)) {
 206                 (void)printf("%s > %s: [|tcp]",
 207                         ipaddr_string(&ip->ip_src),
 208                         ipaddr_string(&ip->ip_dst));
 209                 return;
 210         }
 211
 212         sport = ntohs(tp->th_sport);
 213         dport = ntohs(tp->th_dport);
 214
 215
 216         hlen = TH_OFF(tp) * 4;
 217
 218         /*
 219          * If data present and NFS port used, assume NFS.
 220          * Pass offset of data plus 4 bytes for RPC TCP msg length
 221          * to NFS print routines.
 222          */
 223         if (!qflag) {
 224                 if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
 225                     dport == NFS_PORT) {
 226                         nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
 227                                      (u_char *)ip);
 228                         return;
 229                 } else if ((u_char *)tp + 4 + sizeof(struct rpc_msg)
 230                            <= snapend &&
 231                            sport == NFS_PORT) {
 232                         nfsreply_print((u_char *)tp + hlen + 4, length - hlen,
 233                                        (u_char *)ip);
 234                         return;
 235                 }
 236         }
 237 #ifdef INET6
 238         if (ip6) {
 239                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 240                         (void)printf("%s.%s > %s.%s: ",
 241                                 ip6addr_string(&ip6->ip6_src),
 242                                 tcpport_string(sport),
 243                                 ip6addr_string(&ip6->ip6_dst),
 244                                 tcpport_string(dport));
 245                 } else {
 246                         (void)printf("%s > %s: ",
 247                                 tcpport_string(sport), tcpport_string(dport));
 248                 }
 249         } else
 250 #endif /*INET6*/
 251         {
 252                 if (ip->ip_p == IPPROTO_TCP) {
 253                         (void)printf("%s.%s > %s.%s: ",
 254                                 ipaddr_string(&ip->ip_src),
 255                                 tcpport_string(sport),
 256                                 ipaddr_string(&ip->ip_dst),
 257                                 tcpport_string(dport));
 258                 } else {
 259                         (void)printf("%s > %s: ",
 260                                 tcpport_string(sport), tcpport_string(dport));
 261                 }
 262         }
 263
 264         TCHECK(*tp);
 265
 266         seq = (u_int32_t)ntohl(tp->th_seq);
 267         ack = (u_int32_t)ntohl(tp->th_ack);
 268         win = ntohs(tp->th_win);
 269         urp = ntohs(tp->th_urp);
 270
 271         if (qflag) {
 272                 (void)printf("tcp %d", length - TH_OFF(tp) * 4);
 273                 return;
 274         }
 275         if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
 276                                       TH_ECNECHO|TH_CWR)) {
 277                 if (flags & TH_SYN)
 278                         putchar('S');
 279                 if (flags & TH_FIN)
 280                         putchar('F');
 281                 if (flags & TH_RST)
 282                         putchar('R');
 283                 if (flags & TH_PUSH)
 284                         putchar('P');
 285                 if (flags & TH_CWR)
 286                         putchar('W');   /* congestion _W_indow reduced (ECN) */
 287                 if (flags & TH_ECNECHO)
 288                         putchar('E');   /* ecn _E_cho sent (ECN) */
 289         } else
 290                 putchar('.');
 291
 292         if (!Sflag && (flags & TH_ACK)) {
 293                 register struct tcp_seq_hash *th;
 294                 register int rev;
 295                 struct tha tha;
 296                 /*
 297                  * Find (or record) the initial sequence numbers for
 298                  * this conversation.  (we pick an arbitrary
 299                  * collating order so there's only one entry for
 300                  * both directions).
 301                  */
 302 #ifdef INET6
 303                 memset(&tha, 0, sizeof(tha));
 304                 rev = 0;
 305                 if (ip6) {
 306                         if (sport > dport)
 307                                 rev = 1;
 308                         else if (sport == dport) {
 309                                 int i;
 310
 311                                 for (i = 0; i < 4; i++) {
 312                                         if (((u_int32_t *)(&ip6->ip6_src))[i] >
 313                                             ((u_int32_t *)(&ip6->ip6_dst))[i]) {
 314                                                 rev = 1;
 315                                                 break;
 316                                         }
 317                                 }
 318                         }
 319                         if (rev) {
 320                                 tha.src = ip6->ip6_dst;
 321                                 tha.dst = ip6->ip6_src;
 322                                 tha.port = dport << 16 | sport;
 323                         } else {
 324                                 tha.dst = ip6->ip6_dst;
 325                                 tha.src = ip6->ip6_src;
 326                                 tha.port = sport << 16 | dport;
 327                         }
 328                 } else {
 329                         if (sport > dport ||
 330                             (sport == dport &&
 331                              ip->ip_src.s_addr > ip->ip_dst.s_addr)) {
 332                                 rev = 1;
 333                         }
 334                         if (rev) {
 335                                 *(struct in_addr *)&tha.src = ip->ip_dst;
 336                                 *(struct in_addr *)&tha.dst = ip->ip_src;
 337                                 tha.port = dport << 16 | sport;
 338                         } else {
 339                                 *(struct in_addr *)&tha.dst = ip->ip_dst;
 340                                 *(struct in_addr *)&tha.src = ip->ip_src;
 341                                 tha.port = sport << 16 | dport;
 342                         }
 343                 }
 344 #else
 345                 if (sport < dport ||
 346                     (sport == dport &&
 347                      ip->ip_src.s_addr < ip->ip_dst.s_addr)) {
 348                         tha.src = ip->ip_src, tha.dst = ip->ip_dst;
 349                         tha.port = sport << 16 | dport;
 350                         rev = 0;
 351                 } else {
 352                         tha.src = ip->ip_dst, tha.dst = ip->ip_src;
 353                         tha.port = dport << 16 | sport;
 354                         rev = 1;
 355                 }
 356 #endif
 357
 358                 threv = rev;
 359                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 360                      th->nxt; th = th->nxt)
 361                         if (!memcmp((char *)&tha, (char *)&th->addr,
 362                                   sizeof(th->addr)))
 363                                 break;
 364
 365                 if (!th->nxt || (flags & TH_SYN)) {
 366                         /* didn't find it or new conversation */
 367                         if (th->nxt == NULL) {
 368                                 th->nxt = (struct tcp_seq_hash *)
 369                                         calloc(1, sizeof(*th));
 370                                 if (th->nxt == NULL)
 371                                         error("tcp_print: calloc");
 372                         }
 373                         th->addr = tha;
 374                         if (rev)
 375                                 th->ack = seq, th->seq = ack - 1;
 376                         else
 377                                 th->seq = seq, th->ack = ack - 1;
 378                 } else {
 379                         if (rev)
 380                                 seq -= th->ack, ack -= th->seq;
 381                         else
 382                                 seq -= th->seq, ack -= th->ack;
 383                 }
 384
 385                 thseq = th->seq;
 386                 thack = th->ack;
 387         } else {
 388                 /*fool gcc*/
 389                 thseq = thack = threv = 0;
 390         }
 391         if (hlen > length) {
 392                 (void)printf(" [bad hdr length]");
 393                 return;
 394         }
 395
 396         if (IP_V(ip) == 4 && vflag && !fragmented) {
 397                 int sum;
 398                 if (TTEST2(tp->th_sport, length)) {
 399                         sum = tcp_cksum(ip, tp, length);
 400                         if (sum != 0)
 401                                 (void)printf(" [bad tcp cksum %x!]", sum);
 402                         else
 403                                 (void)printf(" [tcp sum ok]");
 404                 }
 405         }
 406 #ifdef INET6
 407         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
 408                 int sum;
 409                 if (TTEST2(tp->th_sport, length)) {
 410                         sum = tcp6_cksum(ip6, tp, length);
 411                         if (sum != 0)
 412                                 (void)printf(" [bad tcp cksum %x!]", sum);
 413                         else
 414                                 (void)printf(" [tcp sum ok]");
 415                 }
 416         }
 417 #endif
 418
 419         length -= hlen;
 420         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
 421                 (void)printf(" %u:%u(%d)", seq, seq + length, length);
 422         if (flags & TH_ACK)
 423                 (void)printf(" ack %u", ack);
 424
 425         (void)printf(" win %d", win);
 426
 427         if (flags & TH_URG)
 428                 (void)printf(" urg %d", urp);
 429         /*
 430          * Handle any options.
 431          */
 432         if ((hlen -= sizeof(*tp)) > 0) {
 433                 register const u_char *cp;
 434                 register int i, opt, len, datalen;
 435
 436                 cp = (const u_char *)tp + sizeof(*tp);
 437                 putchar(' ');
 438                 ch = '<';
 439                 while (hlen > 0) {
 440                         putchar(ch);
 441                         TCHECK(*cp);
 442                         opt = *cp++;
 443                         if (ZEROLENOPT(opt))
 444                                 len = 1;
 445                         else {
 446                                 TCHECK(*cp);
 447                                 len = *cp++;    /* total including type, len */
 448                                 if (len < 2 || len > hlen)
 449                                         goto bad;
 450                                 --hlen;         /* account for length byte */
 451                         }
 452                         --hlen;                 /* account for type byte */
 453                         datalen = 0;
 454
 455 /* Bail if "l" bytes of data are not left or were not captured  */
 456 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 457
 458                         switch (opt) {
 459
 460                         case TCPOPT_MAXSEG:
 461                                 (void)printf("mss");
 462                                 datalen = 2;
 463                                 LENCHECK(datalen);
 464                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 465
 466                                 break;
 467
 468                         case TCPOPT_EOL:
 469                                 (void)printf("eol");
 470                                 break;
 471
 472                         case TCPOPT_NOP:
 473                                 (void)printf("nop");
 474                                 break;
 475
 476                         case TCPOPT_WSCALE:
 477                                 (void)printf("wscale");
 478                                 datalen = 1;
 479                                 LENCHECK(datalen);
 480                                 (void)printf(" %u", *cp);
 481                                 break;
 482
 483                         case TCPOPT_SACKOK:
 484                                 (void)printf("sackOK");
 485                                 break;
 486
 487                         case TCPOPT_SACK:
 488                                 (void)printf("sack");
 489                                 datalen = len - 2;
 490                                 if (datalen % 8 != 0) {
 491                                         (void)printf(" malformed sack ");
 492                                 } else {
 493                                         u_int32_t s, e;
 494
 495                                         (void)printf(" sack %d ", datalen / 8);
 496                                         for (i = 0; i < datalen; i += 8) {
 497                                                 LENCHECK(i + 4);
 498                                                 s = EXTRACT_32BITS(cp + i);
 499                                                 LENCHECK(i + 8);
 500                                                 e = EXTRACT_32BITS(cp + i + 4);
 501                                                 if (threv) {
 502                                                         s -= thseq;
 503                                                         e -= thseq;
 504                                                 } else {
 505                                                         s -= thack;
 506                                                         e -= thack;
 507                                                 }
 508                                                 (void)printf("{%u:%u}", s, e);
 509                                         }
 510                                         (void)printf(" ");
 511                                 }
 512                                 break;
 513
 514                         case TCPOPT_ECHO:
 515                                 (void)printf("echo");
 516                                 datalen = 4;
 517                                 LENCHECK(datalen);
 518                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 519                                 break;
 520
 521                         case TCPOPT_ECHOREPLY:
 522                                 (void)printf("echoreply");
 523                                 datalen = 4;
 524                                 LENCHECK(datalen);
 525                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 526                                 break;
 527
 528                         case TCPOPT_TIMESTAMP:
 529                                 (void)printf("timestamp");
 530                                 datalen = 8;
 531                                 LENCHECK(4);
 532                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 533                                 LENCHECK(datalen);
 534                                 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
 535                                 break;
 536
 537                         case TCPOPT_CC:
 538                                 (void)printf("cc");
 539                                 datalen = 4;
 540                                 LENCHECK(datalen);
 541                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 542                                 break;
 543
 544                         case TCPOPT_CCNEW:
 545                                 (void)printf("ccnew");
 546                                 datalen = 4;
 547                                 LENCHECK(datalen);
 548                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 549                                 break;
 550
 551                         case TCPOPT_CCECHO:
 552                                 (void)printf("ccecho");
 553                                 datalen = 4;
 554                                 LENCHECK(datalen);
 555                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 556                                 break;
 557
 558                         default:
 559                                 (void)printf("opt-%d:", opt);
 560                                 datalen = len - 2;
 561                                 for (i = 0; i < datalen; ++i) {
 562                                         LENCHECK(i);
 563                                         (void)printf("%02x", cp[i]);
 564                                 }
 565                                 break;
 566                         }
 567
 568                         /* Account for data printed */
 569                         cp += datalen;
 570                         hlen -= datalen;
 571
 572                         /* Check specification against observed length */
 573                         ++datalen;                      /* option octet */
 574                         if (!ZEROLENOPT(opt))
 575                                 ++datalen;              /* size octet */
 576                         if (datalen != len)
 577                                 (void)printf("[len %d]", len);
 578                         ch = ',';
 579                         if (opt == TCPOPT_EOL)
 580                                 break;
 581                 }
 582                 putchar('>');
 583         }
 584
 585         if (length <= 0)
 586                 return;
 587
 588         /*
 589          * Decode payload if necessary.
 590          */
 591         bp += TH_OFF(tp) * 4;
 592         if (flags & TH_RST) {
 593                 if (vflag)
 594                         print_tcp_rst_data(bp, length);
 595         } else {
 596                 if (sport == TELNET_PORT || dport == TELNET_PORT) {
 597                         if (!qflag && vflag)
 598                                 telnet_print(bp, length);
 599                 } else if (sport == BGP_PORT || dport == BGP_PORT)
 600                         bgp_print(bp, length);
 601                 else if (sport == PPTP_PORT || dport == PPTP_PORT)
 602                         pptp_print(bp, length);
 603                 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 604                         nbt_tcp_print(bp, length);
 605                 else if (sport == BXXP_PORT || dport == BXXP_PORT)
 606                         bxxp_print(bp, length);
 607                 else if (length > 2 &&
 608                     (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT)) {
 609                         /* TCP DNS query has 2byte length at the head */
 610                         ns_print(bp + 2, length - 2);
 611                 } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 612                         msdp_print(bp, length);
 613                 }
 614         }
 615         return;
 616 bad:
 617         fputs("[bad opt]", stdout);
 618         if (ch != '\0')
 619                 putchar('>');
 620         return;
 621 trunc:
 622         fputs("[|tcp]", stdout);
 623         if (ch != '\0')
 624                 putchar('>');
 625 }
 626
 627 /*
 628  * RFC1122 says the following on data in RST segments:
 629  *
 630  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 631  *
 632  *            A TCP SHOULD allow a received RST segment to include data.
 633  *
 634  *            DISCUSSION
 635  *                 It has been suggested that a RST segment could contain
 636  *                 ASCII text that encoded and explained the cause of the
 637  *                 RST.  No standard has yet been established for such
 638  *                 data.
 639  *
 640  */
 641
 642 static void
 643 print_tcp_rst_data(register const u_char *sp, u_int length)
 644 {
 645         int c;
 646
 647         if (TTEST2(*sp, length))
 648                 printf(" [RST");
 649         else
 650                 printf(" [!RST");
 651         if (length > MAX_RST_DATA_LEN) {
 652                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 653                 putchar('+');                   /* indicate we truncate */
 654         }
 655         putchar(' ');
 656         while (length-- && sp <= snapend) {
 657                 c = *sp++;
 658                 safeputchar(c);
 659         }
 660         putchar(']');
 661 }