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 1.96 2002-07-21 20:56:24 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
  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 BEEP_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         hlen = TH_OFF(tp) * 4;
 216
 217         /*
 218          * If data present and NFS port used, assume NFS.
 219          * Pass offset of data plus 4 bytes for RPC TCP msg length
 220          * to NFS print routines.
 221          */
 222         if (!qflag) {
 223                 if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
 224                     dport == NFS_PORT) {
 225                         nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
 226                                      (u_char *)ip);
 227                         return;
 228                 } else if ((u_char *)tp + 4 + sizeof(struct rpc_msg)
 229                            <= snapend &&
 230                            sport == NFS_PORT) {
 231                         nfsreply_print((u_char *)tp + hlen + 4, length - hlen,
 232                                        (u_char *)ip);
 233                         return;
 234                 }
 235         }
 236 #ifdef INET6
 237         if (ip6) {
 238                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 239                         (void)printf("%s.%s > %s.%s: ",
 240                                 ip6addr_string(&ip6->ip6_src),
 241                                 tcpport_string(sport),
 242                                 ip6addr_string(&ip6->ip6_dst),
 243                                 tcpport_string(dport));
 244                 } else {
 245                         (void)printf("%s > %s: ",
 246                                 tcpport_string(sport), tcpport_string(dport));
 247                 }
 248         } else
 249 #endif /*INET6*/
 250         {
 251                 if (ip->ip_p == IPPROTO_TCP) {
 252                         (void)printf("%s.%s > %s.%s: ",
 253                                 ipaddr_string(&ip->ip_src),
 254                                 tcpport_string(sport),
 255                                 ipaddr_string(&ip->ip_dst),
 256                                 tcpport_string(dport));
 257                 } else {
 258                         (void)printf("%s > %s: ",
 259                                 tcpport_string(sport), tcpport_string(dport));
 260                 }
 261         }
 262
 263         TCHECK(*tp);
 264
 265         seq = (u_int32_t)ntohl(tp->th_seq);
 266         ack = (u_int32_t)ntohl(tp->th_ack);
 267         win = ntohs(tp->th_win);
 268         urp = ntohs(tp->th_urp);
 269
 270         if (qflag) {
 271                 (void)printf("tcp %d", length - TH_OFF(tp) * 4);
 272                 return;
 273         }
 274         if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
 275                                       TH_ECNECHO|TH_CWR)) {
 276                 if (flags & TH_SYN)
 277                         putchar('S');
 278                 if (flags & TH_FIN)
 279                         putchar('F');
 280                 if (flags & TH_RST)
 281                         putchar('R');
 282                 if (flags & TH_PUSH)
 283                         putchar('P');
 284                 if (flags & TH_CWR)
 285                         putchar('W');   /* congestion _W_indow reduced (ECN) */
 286                 if (flags & TH_ECNECHO)
 287                         putchar('E');   /* ecn _E_cho sent (ECN) */
 288         } else
 289                 putchar('.');
 290
 291         if (!Sflag && (flags & TH_ACK)) {
 292                 register struct tcp_seq_hash *th;
 293                 register int rev;
 294                 struct tha tha;
 295                 /*
 296                  * Find (or record) the initial sequence numbers for
 297                  * this conversation.  (we pick an arbitrary
 298                  * collating order so there's only one entry for
 299                  * both directions).
 300                  */
 301 #ifdef INET6
 302                 memset(&tha, 0, sizeof(tha));
 303                 rev = 0;
 304                 if (ip6) {
 305                         if (sport > dport)
 306                                 rev = 1;
 307                         else if (sport == dport) {
 308                                 int i;
 309
 310                                 for (i = 0; i < 4; i++) {
 311                                         if (((u_int32_t *)(&ip6->ip6_src))[i] >
 312                                             ((u_int32_t *)(&ip6->ip6_dst))[i]) {
 313                                                 rev = 1;
 314                                                 break;
 315                                         }
 316                                 }
 317                         }
 318                         if (rev) {
 319                                 tha.src = ip6->ip6_dst;
 320                                 tha.dst = ip6->ip6_src;
 321                                 tha.port = dport << 16 | sport;
 322                         } else {
 323                                 tha.dst = ip6->ip6_dst;
 324                                 tha.src = ip6->ip6_src;
 325                                 tha.port = sport << 16 | dport;
 326                         }
 327                 } else {
 328                         if (sport > dport ||
 329                             (sport == dport &&
 330                              ip->ip_src.s_addr > ip->ip_dst.s_addr)) {
 331                                 rev = 1;
 332                         }
 333                         if (rev) {
 334                                 *(struct in_addr *)&tha.src = ip->ip_dst;
 335                                 *(struct in_addr *)&tha.dst = ip->ip_src;
 336                                 tha.port = dport << 16 | sport;
 337                         } else {
 338                                 *(struct in_addr *)&tha.dst = ip->ip_dst;
 339                                 *(struct in_addr *)&tha.src = ip->ip_src;
 340                                 tha.port = sport << 16 | dport;
 341                         }
 342                 }
 343 #else
 344                 if (sport < dport ||
 345                     (sport == dport &&
 346                      ip->ip_src.s_addr < ip->ip_dst.s_addr)) {
 347                         tha.src = ip->ip_src, tha.dst = ip->ip_dst;
 348                         tha.port = sport << 16 | dport;
 349                         rev = 0;
 350                 } else {
 351                         tha.src = ip->ip_dst, tha.dst = ip->ip_src;
 352                         tha.port = dport << 16 | sport;
 353                         rev = 1;
 354                 }
 355 #endif
 356
 357                 threv = rev;
 358                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 359                      th->nxt; th = th->nxt)
 360                         if (!memcmp((char *)&tha, (char *)&th->addr,
 361                                   sizeof(th->addr)))
 362                                 break;
 363
 364                 if (!th->nxt || (flags & TH_SYN)) {
 365                         /* didn't find it or new conversation */
 366                         if (th->nxt == NULL) {
 367                                 th->nxt = (struct tcp_seq_hash *)
 368                                         calloc(1, sizeof(*th));
 369                                 if (th->nxt == NULL)
 370                                         error("tcp_print: calloc");
 371                         }
 372                         th->addr = tha;
 373                         if (rev)
 374                                 th->ack = seq, th->seq = ack - 1;
 375                         else
 376                                 th->seq = seq, th->ack = ack - 1;
 377                 } else {
 378                         if (rev)
 379                                 seq -= th->ack, ack -= th->seq;
 380                         else
 381                                 seq -= th->seq, ack -= th->ack;
 382                 }
 383
 384                 thseq = th->seq;
 385                 thack = th->ack;
 386         } else {
 387                 /*fool gcc*/
 388                 thseq = thack = threv = 0;
 389         }
 390         if (hlen > length) {
 391                 (void)printf(" [bad hdr length]");
 392                 return;
 393         }
 394
 395         if (IP_V(ip) == 4 && vflag && !fragmented) {
 396                 u_int16_t sum, tcp_sum;
 397                 if (TTEST2(tp->th_sport, length)) {
 398                         sum = tcp_cksum(ip, tp, length);
 399                         if (sum != 0) {
 400                                 tcp_sum = ntohs(tp->th_sum);
 401                                 (void)printf(" [bad tcp cksum %x (->%x)!]",
 402                                     tcp_sum, in_cksum_shouldbe(tcp_sum, sum));
 403                         } else
 404                                 (void)printf(" [tcp sum ok]");
 405                 }
 406         }
 407 #ifdef INET6
 408         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
 409                 int sum;
 410                 if (TTEST2(tp->th_sport, length)) {
 411                         sum = tcp6_cksum(ip6, tp, length);
 412                         if (sum != 0)
 413                                 (void)printf(" [bad tcp cksum %x!]", sum);
 414                         else
 415                                 (void)printf(" [tcp sum ok]");
 416                 }
 417         }
 418 #endif
 419
 420         length -= hlen;
 421         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
 422                 (void)printf(" %u:%u(%u)", seq, seq + length, length);
 423         if (flags & TH_ACK)
 424                 (void)printf(" ack %u", ack);
 425
 426         (void)printf(" win %d", win);
 427
 428         if (flags & TH_URG)
 429                 (void)printf(" urg %d", urp);
 430         /*
 431          * Handle any options.
 432          */
 433         if ((hlen -= sizeof(*tp)) > 0) {
 434                 register const u_char *cp;
 435                 register int i, opt, len, datalen;
 436
 437                 cp = (const u_char *)tp + sizeof(*tp);
 438                 putchar(' ');
 439                 ch = '<';
 440                 while (hlen > 0) {
 441                         putchar(ch);
 442                         TCHECK(*cp);
 443                         opt = *cp++;
 444                         if (ZEROLENOPT(opt))
 445                                 len = 1;
 446                         else {
 447                                 TCHECK(*cp);
 448                                 len = *cp++;    /* total including type, len */
 449                                 if (len < 2 || len > hlen)
 450                                         goto bad;
 451                                 --hlen;         /* account for length byte */
 452                         }
 453                         --hlen;                 /* account for type byte */
 454                         datalen = 0;
 455
 456 /* Bail if "l" bytes of data are not left or were not captured  */
 457 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 458
 459                         switch (opt) {
 460
 461                         case TCPOPT_MAXSEG:
 462                                 (void)printf("mss");
 463                                 datalen = 2;
 464                                 LENCHECK(datalen);
 465                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 466
 467                                 break;
 468
 469                         case TCPOPT_EOL:
 470                                 (void)printf("eol");
 471                                 break;
 472
 473                         case TCPOPT_NOP:
 474                                 (void)printf("nop");
 475                                 break;
 476
 477                         case TCPOPT_WSCALE:
 478                                 (void)printf("wscale");
 479                                 datalen = 1;
 480                                 LENCHECK(datalen);
 481                                 (void)printf(" %u", *cp);
 482                                 break;
 483
 484                         case TCPOPT_SACKOK:
 485                                 (void)printf("sackOK");
 486                                 break;
 487
 488                         case TCPOPT_SACK:
 489                                 (void)printf("sack");
 490                                 datalen = len - 2;
 491                                 if (datalen % 8 != 0) {
 492                                         (void)printf(" malformed sack ");
 493                                 } else {
 494                                         u_int32_t s, e;
 495
 496                                         (void)printf(" sack %d ", datalen / 8);
 497                                         for (i = 0; i < datalen; i += 8) {
 498                                                 LENCHECK(i + 4);
 499                                                 s = EXTRACT_32BITS(cp + i);
 500                                                 LENCHECK(i + 8);
 501                                                 e = EXTRACT_32BITS(cp + i + 4);
 502                                                 if (threv) {
 503                                                         s -= thseq;
 504                                                         e -= thseq;
 505                                                 } else {
 506                                                         s -= thack;
 507                                                         e -= thack;
 508                                                 }
 509                                                 (void)printf("{%u:%u}", s, e);
 510                                         }
 511                                         (void)printf(" ");
 512                                 }
 513                                 break;
 514
 515                         case TCPOPT_ECHO:
 516                                 (void)printf("echo");
 517                                 datalen = 4;
 518                                 LENCHECK(datalen);
 519                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 520                                 break;
 521
 522                         case TCPOPT_ECHOREPLY:
 523                                 (void)printf("echoreply");
 524                                 datalen = 4;
 525                                 LENCHECK(datalen);
 526                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 527                                 break;
 528
 529                         case TCPOPT_TIMESTAMP:
 530                                 (void)printf("timestamp");
 531                                 datalen = 8;
 532                                 LENCHECK(4);
 533                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 534                                 LENCHECK(datalen);
 535                                 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
 536                                 break;
 537
 538                         case TCPOPT_CC:
 539                                 (void)printf("cc");
 540                                 datalen = 4;
 541                                 LENCHECK(datalen);
 542                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 543                                 break;
 544
 545                         case TCPOPT_CCNEW:
 546                                 (void)printf("ccnew");
 547                                 datalen = 4;
 548                                 LENCHECK(datalen);
 549                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 550                                 break;
 551
 552                         case TCPOPT_CCECHO:
 553                                 (void)printf("ccecho");
 554                                 datalen = 4;
 555                                 LENCHECK(datalen);
 556                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 557                                 break;
 558
 559                         default:
 560                                 (void)printf("opt-%d:", opt);
 561                                 datalen = len - 2;
 562                                 for (i = 0; i < datalen; ++i) {
 563                                         LENCHECK(i);
 564                                         (void)printf("%02x", cp[i]);
 565                                 }
 566                                 break;
 567                         }
 568
 569                         /* Account for data printed */
 570                         cp += datalen;
 571                         hlen -= datalen;
 572
 573                         /* Check specification against observed length */
 574                         ++datalen;                      /* option octet */
 575                         if (!ZEROLENOPT(opt))
 576                                 ++datalen;              /* size octet */
 577                         if (datalen != len)
 578                                 (void)printf("[len %d]", len);
 579                         ch = ',';
 580                         if (opt == TCPOPT_EOL)
 581                                 break;
 582                 }
 583                 putchar('>');
 584         }
 585
 586         if (length <= 0)
 587                 return;
 588
 589         /*
 590          * Decode payload if necessary.
 591          */
 592         bp += TH_OFF(tp) * 4;
 593         if (flags & TH_RST) {
 594                 if (vflag)
 595                         print_tcp_rst_data(bp, length);
 596         } else {
 597                 if (sport == TELNET_PORT || dport == TELNET_PORT) {
 598                         if (!qflag && vflag)
 599                                 telnet_print(bp, length);
 600                 } else if (sport == BGP_PORT || dport == BGP_PORT)
 601                         bgp_print(bp, length);
 602                 else if (sport == PPTP_PORT || dport == PPTP_PORT)
 603                         pptp_print(bp, length);
 604 #ifdef TCPDUMP_DO_SMB
 605                 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 606                         nbt_tcp_print(bp, length);
 607 #endif
 608                 else if (sport == BEEP_PORT || dport == BEEP_PORT)
 609                         beep_print(bp, length);
 610                 else if (length > 2 &&
 611                     (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT)) {
 612                         /*
 613                          * TCP DNS query has 2byte length at the head.
 614                          * XXX packet could be unaligned, it can go strange
 615                          */
 616                         ns_print(bp + 2, length - 2);
 617                 } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
 618                         msdp_print(bp, length);
 619                 }
 620         }
 621         return;
 622 bad:
 623         fputs("[bad opt]", stdout);
 624         if (ch != '\0')
 625                 putchar('>');
 626         return;
 627 trunc:
 628         fputs("[|tcp]", stdout);
 629         if (ch != '\0')
 630                 putchar('>');
 631 }
 632
 633 /*
 634  * RFC1122 says the following on data in RST segments:
 635  *
 636  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 637  *
 638  *            A TCP SHOULD allow a received RST segment to include data.
 639  *
 640  *            DISCUSSION
 641  *                 It has been suggested that a RST segment could contain
 642  *                 ASCII text that encoded and explained the cause of the
 643  *                 RST.  No standard has yet been established for such
 644  *                 data.
 645  *
 646  */
 647
 648 static void
 649 print_tcp_rst_data(register const u_char *sp, u_int length)
 650 {
 651         int c;
 652
 653         if (TTEST2(*sp, length))
 654                 printf(" [RST");
 655         else
 656                 printf(" [!RST");
 657         if (length > MAX_RST_DATA_LEN) {
 658                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 659                 putchar('+');                   /* indicate we truncate */
 660         }
 661         putchar(' ');
 662         while (length-- && sp <= snapend) {
 663                 c = *sp++;
 664                 safeputchar(c);
 665         }
 666         putchar(']');
 667 }