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 1.86 2001-05-09 01:16:57 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
 103 static int tcp_cksum(register const struct ip *ip,
 104                      register const struct tcphdr *tp,
 105                      register int len)
 106 {
 107         int i, tlen;
 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         register const u_int16_t *sp;
 119         u_int32_t sum;
 120         tlen = ntohs(ip->ip_len) - ((const char *)tp-(const char*)ip);
 121
 122         /* pseudo-header.. */
 123         phu.ph.len = htons(tlen);
 124         phu.ph.mbz = 0;
 125         phu.ph.proto = IPPROTO_TCP;
 126         memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
 127         memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
 128
 129         sp = &phu.pa[0];
 130         sum = sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5];
 131
 132         sp = (const u_int16_t *)tp;
 133
 134         for (i=0; i<(tlen&~1); i+= 2)
 135                 sum += *sp++;
 136
 137         if (tlen & 1) {
 138                 sum += htons( (*(const u_int8_t *)sp) << 8);
 139         }
 140
 141         while (sum > 0xffff)
 142                 sum = (sum & 0xffff) + (sum >> 16);
 143         sum = ~sum & 0xffff;
 144
 145         return (sum);
 146 }
 147
 148 #ifdef INET6
 149 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
 150         int len)
 151 {
 152         int i, tlen;
 153         register const u_int16_t *sp;
 154         u_int32_t sum;
 155         union {
 156                 struct {
 157                         struct in6_addr ph_src;
 158                         struct in6_addr ph_dst;
 159                         u_int32_t       ph_len;
 160                         u_int8_t        ph_zero[3];
 161                         u_int8_t        ph_nxt;
 162                 } ph;
 163                 u_int16_t pa[20];
 164         } phu;
 165
 166         tlen = ntohs(ip6->ip6_plen) + sizeof(struct ip6_hdr) -
 167             ((const char *)tp - (const char*)ip6);
 168
 169         /* pseudo-header */
 170         memset(&phu, 0, sizeof(phu));
 171         phu.ph.ph_src = ip6->ip6_src;
 172         phu.ph.ph_dst = ip6->ip6_dst;
 173         phu.ph.ph_len = htonl(tlen);
 174         phu.ph.ph_nxt = IPPROTO_TCP;
 175
 176         sum = 0;
 177         for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
 178                 sum += phu.pa[i];
 179
 180         sp = (const u_int16_t *)tp;
 181
 182         for (i = 0; i < (tlen & ~1); i += 2)
 183                 sum += *sp++;
 184
 185         if (tlen & 1)
 186                 sum += htons((*(const u_int8_t *)sp) << 8);
 187
 188         while (sum > 0xffff)
 189                 sum = (sum & 0xffff) + (sum >> 16);
 190         sum = ~sum & 0xffff;
 191
 192         return (sum);
 193 }
 194 #endif
 195
 196 void
 197 tcp_print(register const u_char *bp, register u_int length,
 198           register const u_char *bp2, int fragmented)
 199 {
 200         register const struct tcphdr *tp;
 201         register const struct ip *ip;
 202         register u_char flags;
 203         register int hlen;
 204         register char ch;
 205         u_int16_t sport, dport, win, urp;
 206         u_int32_t seq, ack, thseq, thack;
 207         int threv;
 208 #ifdef INET6
 209         register const struct ip6_hdr *ip6;
 210 #endif
 211
 212         tp = (struct tcphdr *)bp;
 213         ip = (struct ip *)bp2;
 214 #ifdef INET6
 215         if (IP_V(ip) == 6)
 216                 ip6 = (struct ip6_hdr *)bp2;
 217         else
 218                 ip6 = NULL;
 219 #endif /*INET6*/
 220         ch = '\0';
 221         if (!TTEST(tp->th_dport)) {
 222                 (void)printf("%s > %s: [|tcp]",
 223                         ipaddr_string(&ip->ip_src),
 224                         ipaddr_string(&ip->ip_dst));
 225                 return;
 226         }
 227
 228         sport = ntohs(tp->th_sport);
 229         dport = ntohs(tp->th_dport);
 230
 231
 232         hlen = TH_OFF(tp) * 4;
 233
 234         /*
 235          * If data present and NFS port used, assume NFS.
 236          * Pass offset of data plus 4 bytes for RPC TCP msg length
 237          * to NFS print routines.
 238          */
 239         if (!qflag) {
 240                 if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
 241                     dport == NFS_PORT) {
 242                         nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
 243                                      (u_char *)ip);
 244                         return;
 245                 } else if ((u_char *)tp + 4 + sizeof(struct rpc_msg)
 246                            <= snapend &&
 247                            sport == NFS_PORT) {
 248                         nfsreply_print((u_char *)tp + hlen + 4,length-hlen,
 249                                        (u_char *)ip);
 250                         return;
 251                 }
 252         }
 253 #ifdef INET6
 254         if (ip6) {
 255                 if (ip6->ip6_nxt == IPPROTO_TCP) {
 256                         (void)printf("%s.%s > %s.%s: ",
 257                                 ip6addr_string(&ip6->ip6_src),
 258                                 tcpport_string(sport),
 259                                 ip6addr_string(&ip6->ip6_dst),
 260                                 tcpport_string(dport));
 261                 } else {
 262                         (void)printf("%s > %s: ",
 263                                 tcpport_string(sport), tcpport_string(dport));
 264                 }
 265         } else
 266 #endif /*INET6*/
 267         {
 268                 if (ip->ip_p == IPPROTO_TCP) {
 269                         (void)printf("%s.%s > %s.%s: ",
 270                                 ipaddr_string(&ip->ip_src),
 271                                 tcpport_string(sport),
 272                                 ipaddr_string(&ip->ip_dst),
 273                                 tcpport_string(dport));
 274                 } else {
 275                         (void)printf("%s > %s: ",
 276                                 tcpport_string(sport), tcpport_string(dport));
 277                 }
 278         }
 279
 280         TCHECK(*tp);
 281
 282         seq = (u_int32_t)ntohl(tp->th_seq);
 283         ack = (u_int32_t)ntohl(tp->th_ack);
 284         win = ntohs(tp->th_win);
 285         urp = ntohs(tp->th_urp);
 286
 287         if (qflag) {
 288                 (void)printf("tcp %d", length - TH_OFF(tp) * 4);
 289                 return;
 290         }
 291         if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
 292                                       TH_ECNECHO|TH_CWR)) {
 293                 if (flags & TH_SYN)
 294                         putchar('S');
 295                 if (flags & TH_FIN)
 296                         putchar('F');
 297                 if (flags & TH_RST)
 298                         putchar('R');
 299                 if (flags & TH_PUSH)
 300                         putchar('P');
 301                 if (flags & TH_CWR)
 302                         putchar('W');   /* congestion _W_indow reduced (ECN) */
 303                 if (flags & TH_ECNECHO)
 304                         putchar('E');   /* ecn _E_cho sent (ECN) */
 305         } else
 306                 putchar('.');
 307
 308         if (!Sflag && (flags & TH_ACK)) {
 309                 register struct tcp_seq_hash *th;
 310                 register int rev;
 311                 struct tha tha;
 312                 /*
 313                  * Find (or record) the initial sequence numbers for
 314                  * this conversation.  (we pick an arbitrary
 315                  * collating order so there's only one entry for
 316                  * both directions).
 317                  */
 318 #ifdef INET6
 319                 memset(&tha, 0, sizeof(tha));
 320                 rev = 0;
 321                 if (ip6) {
 322                         if (sport > dport)
 323                                 rev = 1;
 324                         else if (sport == dport) {
 325                                 int i;
 326
 327                                 for (i = 0; i < 4; i++) {
 328                                         if (((u_int32_t *)(&ip6->ip6_src))[i] >
 329                                             ((u_int32_t *)(&ip6->ip6_dst))[i]) {
 330                                                 rev = 1;
 331                                                 break;
 332                                         }
 333                                 }
 334                         }
 335                         if (rev) {
 336                                 tha.src = ip6->ip6_dst;
 337                                 tha.dst = ip6->ip6_src;
 338                                 tha.port = dport << 16 | sport;
 339                         } else {
 340                                 tha.dst = ip6->ip6_dst;
 341                                 tha.src = ip6->ip6_src;
 342                                 tha.port = sport << 16 | dport;
 343                         }
 344                 } else {
 345                         if (sport > dport ||
 346                             (sport == dport &&
 347                              ip->ip_src.s_addr > ip->ip_dst.s_addr)) {
 348                                 rev = 1;
 349                         }
 350                         if (rev) {
 351                                 *(struct in_addr *)&tha.src = ip->ip_dst;
 352                                 *(struct in_addr *)&tha.dst = ip->ip_src;
 353                                 tha.port = dport << 16 | sport;
 354                         } else {
 355                                 *(struct in_addr *)&tha.dst = ip->ip_dst;
 356                                 *(struct in_addr *)&tha.src = ip->ip_src;
 357                                 tha.port = sport << 16 | dport;
 358                         }
 359                 }
 360 #else
 361                 if (sport < dport ||
 362                     (sport == dport &&
 363                      ip->ip_src.s_addr < ip->ip_dst.s_addr)) {
 364                         tha.src = ip->ip_src, tha.dst = ip->ip_dst;
 365                         tha.port = sport << 16 | dport;
 366                         rev = 0;
 367                 } else {
 368                         tha.src = ip->ip_dst, tha.dst = ip->ip_src;
 369                         tha.port = dport << 16 | sport;
 370                         rev = 1;
 371                 }
 372 #endif
 373
 374                 threv = rev;
 375                 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
 376                      th->nxt; th = th->nxt)
 377                         if (!memcmp((char *)&tha, (char *)&th->addr,
 378                                   sizeof(th->addr)))
 379                                 break;
 380
 381                 if (!th->nxt || (flags & TH_SYN)) {
 382                         /* didn't find it or new conversation */
 383                         if (th->nxt == NULL) {
 384                                 th->nxt = (struct tcp_seq_hash *)
 385                                         calloc(1, sizeof(*th));
 386                                 if (th->nxt == NULL)
 387                                         error("tcp_print: calloc");
 388                         }
 389                         th->addr = tha;
 390                         if (rev)
 391                                 th->ack = seq, th->seq = ack - 1;
 392                         else
 393                                 th->seq = seq, th->ack = ack - 1;
 394                 } else {
 395                         if (rev)
 396                                 seq -= th->ack, ack -= th->seq;
 397                         else
 398                                 seq -= th->seq, ack -= th->ack;
 399                 }
 400
 401                 thseq = th->seq;
 402                 thack = th->ack;
 403         } else {
 404                 /*fool gcc*/
 405                 thseq = thack = threv = 0;
 406         }
 407         if (hlen > length) {
 408                 (void)printf(" [bad hdr length]");
 409                 return;
 410         }
 411
 412         if (IP_V(ip) == 4 && vflag && !fragmented) {
 413                 int sum;
 414                 if (TTEST2(tp->th_sport, length)) {
 415                         sum = tcp_cksum(ip, tp, length);
 416                         if (sum != 0)
 417                                 (void)printf(" [bad tcp cksum %x!]", sum);
 418                         else
 419                                 (void)printf(" [tcp sum ok]");
 420                 }
 421         }
 422 #ifdef INET6
 423         if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
 424                 int sum;
 425                 if (TTEST2(tp->th_sport, length)) {
 426                         sum = tcp6_cksum(ip6, tp, length);
 427                         if (sum != 0)
 428                                 (void)printf(" [bad tcp cksum %x!]", sum);
 429                         else
 430                                 (void)printf(" [tcp sum ok]");
 431                 }
 432         }
 433 #endif
 434
 435         length -= hlen;
 436         if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
 437                 (void)printf(" %u:%u(%d)", seq, seq + length, length);
 438         if (flags & TH_ACK)
 439                 (void)printf(" ack %u", ack);
 440
 441         (void)printf(" win %d", win);
 442
 443         if (flags & TH_URG)
 444                 (void)printf(" urg %d", urp);
 445         /*
 446          * Handle any options.
 447          */
 448         if ((hlen -= sizeof(*tp)) > 0) {
 449                 register const u_char *cp;
 450                 register int i, opt, len, datalen;
 451
 452                 cp = (const u_char *)tp + sizeof(*tp);
 453                 putchar(' ');
 454                 ch = '<';
 455                 while (hlen > 0) {
 456                         putchar(ch);
 457                         TCHECK(*cp);
 458                         opt = *cp++;
 459                         if (ZEROLENOPT(opt))
 460                                 len = 1;
 461                         else {
 462                                 TCHECK(*cp);
 463                                 len = *cp++;    /* total including type, len */
 464                                 if (len < 2 || len > hlen)
 465                                         goto bad;
 466                                 --hlen;         /* account for length byte */
 467                         }
 468                         --hlen;                 /* account for type byte */
 469                         datalen = 0;
 470
 471 /* Bail if "l" bytes of data are not left or were not captured  */
 472 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
 473
 474                         switch (opt) {
 475
 476                         case TCPOPT_MAXSEG:
 477                                 (void)printf("mss");
 478                                 datalen = 2;
 479                                 LENCHECK(datalen);
 480                                 (void)printf(" %u", EXTRACT_16BITS(cp));
 481
 482                                 break;
 483
 484                         case TCPOPT_EOL:
 485                                 (void)printf("eol");
 486                                 break;
 487
 488                         case TCPOPT_NOP:
 489                                 (void)printf("nop");
 490                                 break;
 491
 492                         case TCPOPT_WSCALE:
 493                                 (void)printf("wscale");
 494                                 datalen = 1;
 495                                 LENCHECK(datalen);
 496                                 (void)printf(" %u", *cp);
 497                                 break;
 498
 499                         case TCPOPT_SACKOK:
 500                                 (void)printf("sackOK");
 501                                 break;
 502
 503                         case TCPOPT_SACK:
 504                                 (void)printf("sack");
 505                                 datalen = len - 2;
 506                                 if (datalen % 8 != 0) {
 507                                         (void)printf(" malformed sack ");
 508                                 } else {
 509                                         u_int32_t s, e;
 510
 511                                         (void)printf(" sack %d ", datalen / 8);
 512                                         for (i = 0; i < datalen; i += 8) {
 513                                                 LENCHECK(i + 4);
 514                                                 s = EXTRACT_32BITS(cp + i);
 515                                                 LENCHECK(i + 8);
 516                                                 e = EXTRACT_32BITS(cp + i + 4);
 517                                                 if (threv) {
 518                                                         s -= thseq;
 519                                                         e -= thseq;
 520                                                 } else {
 521                                                         s -= thack;
 522                                                         e -= thack;
 523                                                 }
 524                                                 (void)printf("{%u:%u}", s, e);
 525                                         }
 526                                         (void)printf(" ");
 527                                 }
 528                                 break;
 529
 530                         case TCPOPT_ECHO:
 531                                 (void)printf("echo");
 532                                 datalen = 4;
 533                                 LENCHECK(datalen);
 534                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 535                                 break;
 536
 537                         case TCPOPT_ECHOREPLY:
 538                                 (void)printf("echoreply");
 539                                 datalen = 4;
 540                                 LENCHECK(datalen);
 541                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 542                                 break;
 543
 544                         case TCPOPT_TIMESTAMP:
 545                                 (void)printf("timestamp");
 546                                 datalen = 8;
 547                                 LENCHECK(4);
 548                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 549                                 LENCHECK(datalen);
 550                                 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
 551                                 break;
 552
 553                         case TCPOPT_CC:
 554                                 (void)printf("cc");
 555                                 datalen = 4;
 556                                 LENCHECK(datalen);
 557                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 558                                 break;
 559
 560                         case TCPOPT_CCNEW:
 561                                 (void)printf("ccnew");
 562                                 datalen = 4;
 563                                 LENCHECK(datalen);
 564                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 565                                 break;
 566
 567                         case TCPOPT_CCECHO:
 568                                 (void)printf("ccecho");
 569                                 datalen = 4;
 570                                 LENCHECK(datalen);
 571                                 (void)printf(" %u", EXTRACT_32BITS(cp));
 572                                 break;
 573
 574                         default:
 575                                 (void)printf("opt-%d:", opt);
 576                                 datalen = len - 2;
 577                                 for (i = 0; i < datalen; ++i) {
 578                                         LENCHECK(i);
 579                                         (void)printf("%02x", cp[i]);
 580                                 }
 581                                 break;
 582                         }
 583
 584                         /* Account for data printed */
 585                         cp += datalen;
 586                         hlen -= datalen;
 587
 588                         /* Check specification against observed length */
 589                         ++datalen;                      /* option octet */
 590                         if (!ZEROLENOPT(opt))
 591                                 ++datalen;              /* size octet */
 592                         if (datalen != len)
 593                                 (void)printf("[len %d]", len);
 594                         ch = ',';
 595                         if (opt == TCPOPT_EOL)
 596                                 break;
 597                 }
 598                 putchar('>');
 599         }
 600
 601         if (length <= 0)
 602                 return;
 603
 604         /*
 605          * Decode payload if necessary.
 606          */
 607         bp += TH_OFF(tp) * 4;
 608         if (flags & TH_RST) {
 609                 if (vflag)
 610                         print_tcp_rst_data(bp, length);
 611         } else {
 612                 if (sport == TELNET_PORT || dport == TELNET_PORT) {
 613                         if (!qflag && vflag)
 614                                 telnet_print(bp, length);
 615                 } else if (sport == BGP_PORT || dport == BGP_PORT)
 616                         bgp_print(bp, length);
 617                 else if (sport == PPTP_PORT || dport == PPTP_PORT)
 618                         pptp_print(bp, length);
 619                 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
 620                         nbt_tcp_print(bp, length);
 621                 else if (sport == BXXP_PORT || dport == BXXP_PORT)
 622                         bxxp_print(bp, length);
 623                 else if (length > 2 &&
 624                     (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT)) {
 625                         /* TCP DNS query has 2byte length at the head */
 626                         ns_print(bp + 2, length - 2);
 627                 }
 628         }
 629         return;
 630 bad:
 631         fputs("[bad opt]", stdout);
 632         if (ch != '\0')
 633                 putchar('>');
 634         return;
 635 trunc:
 636         fputs("[|tcp]", stdout);
 637         if (ch != '\0')
 638                 putchar('>');
 639 }
 640
 641 /*
 642  * RFC1122 says the following on data in RST segments:
 643  *
 644  *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 645  *
 646  *            A TCP SHOULD allow a received RST segment to include data.
 647  *
 648  *            DISCUSSION
 649  *                 It has been suggested that a RST segment could contain
 650  *                 ASCII text that encoded and explained the cause of the
 651  *                 RST.  No standard has yet been established for such
 652  *                 data.
 653  *
 654  */
 655
 656 static void
 657 print_tcp_rst_data(register const u_char *sp, u_int length)
 658 {
 659         int c;
 660
 661         if (TTEST2(*sp, length))
 662                 printf(" [RST");
 663         else
 664                 printf(" [!RST");
 665         if (length > MAX_RST_DATA_LEN) {
 666                 length = MAX_RST_DATA_LEN;      /* can use -X for longer */
 667                 putchar('+');                   /* indicate we truncate */
 668         }
 669         putchar(' ');
 670         while (length-- && sp <= snapend) {
 671                 c = *sp++;
 672                 safeputchar(c);
 673         }
 674         putchar(']');
 675 }