The Tcpdump Group git mirrors - tcpdump/blob - tcpdump.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
   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  * Support for splitting captures into multiple files with a maximum
  22  * file size:
  23  *
  24  * Copyright (c) 2001
  25  *      Seth Webster <swebster@sst.ll.mit.edu>
  26  */
  27
  28 #ifndef lint
  29 static const char copyright[] =
  30     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
  31 The Regents of the University of California.  All rights reserved.\n";
  32 static const char rcsid[] =
  33     "@(#) $Header: /tcpdump/master/tcpdump/tcpdump.c,v 1.172 2001-11-15 08:03:41 itojun Exp $ (LBL)";
  34 #endif
  35
  36 /*
  37  * tcpdump - monitor tcp/ip traffic on an ethernet.
  38  *
  39  * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory.
  40  * Mercilessly hacked and occasionally improved since then via the
  41  * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
  42  */
  43
  44 #ifdef HAVE_CONFIG_H
  45 #include "config.h"
  46 #endif
  47
  48 #include <sys/types.h>
  49 #include <sys/time.h>
  50
  51 #include <netinet/in.h>
  52
  53 #include <pcap.h>
  54 #include <signal.h>
  55 #include <stdio.h>
  56 #include <stdlib.h>
  57 #include <string.h>
  58 #include <unistd.h>
  59 #include <ctype.h>
  60
  61
  62 #include "interface.h"
  63 #include "addrtoname.h"
  64 #include "machdep.h"
  65 #include "setsignal.h"
  66 #include "gmt2local.h"
  67
  68 int aflag;                      /* translate network and broadcast addresses */
  69 int dflag;                      /* print filter code */
  70 int eflag;                      /* print ethernet header */
  71 int fflag;                      /* don't translate "foreign" IP address */
  72 int nflag;                      /* leave addresses as numbers */
  73 int Nflag;                      /* remove domains from printed host names */
  74 int Oflag = 1;                  /* run filter code optimizer */
  75 int pflag;                      /* don't go promiscuous */
  76 int qflag;                      /* quick (shorter) output */
  77 int Rflag = 1;                  /* print sequence # field in AH/ESP*/
  78 int sflag = 0;                  /* use the libsmi to translate OIDs */
  79 int Sflag;                      /* print raw TCP sequence numbers */
  80 int tflag = 1;                  /* print packet arrival time */
  81 int uflag = 0;                  /* Print undecoded NFS handles */
  82 int vflag;                      /* verbose */
  83 int xflag;                      /* print packet in hex */
  84 int Xflag;                      /* print packet in ascii as well as hex */
  85 off_t Cflag = 0;                /* rotate dump files after this many bytes */
  86
  87 char *espsecret = NULL;         /* ESP secret key */
  88
  89 int packettype;
  90
  91 int infodelay;
  92 int infoprint;
  93
  94 char *program_name;
  95
  96 int32_t thiszone;               /* seconds offset from gmt to local time */
  97
  98 /* Forwards */
  99 static RETSIGTYPE cleanup(int);
 100 static void usage(void) __attribute__((noreturn));
 101
 102 static void dump_and_trunc(u_char *, const struct pcap_pkthdr *, const u_char *);
 103
 104 #ifdef SIGINFO
 105 RETSIGTYPE requestinfo(int);
 106 #endif
 107
 108 /* Length of saved portion of packet. */
 109 int snaplen = DEFAULT_SNAPLEN;
 110
 111 struct printer {
 112         pcap_handler f;
 113         int type;
 114 };
 115
 116 static struct printer printers[] = {
 117         { arcnet_if_print,      DLT_ARCNET },
 118         { ether_if_print,       DLT_EN10MB },
 119         { token_if_print,       DLT_IEEE802 },
 120 #ifdef DLT_LANE8023
 121         { lane_if_print,        DLT_LANE8023 },
 122 #endif
 123 #ifdef DLT_CIP
 124         { cip_if_print,         DLT_CIP },
 125 #endif
 126 #ifdef DLT_ATM_CLIP
 127         { cip_if_print,         DLT_ATM_CLIP },
 128 #endif
 129         { sl_if_print,          DLT_SLIP },
 130         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 131         { ppp_if_print,         DLT_PPP },
 132         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 133         { fddi_if_print,        DLT_FDDI },
 134         { null_if_print,        DLT_NULL },
 135 #ifdef DLT_LOOP
 136         { null_if_print,        DLT_LOOP },
 137 #endif
 138         { raw_if_print,         DLT_RAW },
 139         { atm_if_print,         DLT_ATM_RFC1483 },
 140 #ifdef DLT_C_HDLC
 141         { chdlc_if_print,       DLT_C_HDLC },
 142 #endif
 143 #ifdef DLT_HDLC
 144         { chdlc_if_print,       DLT_HDLC },
 145 #endif
 146 #ifdef DLT_PPP_SERIAL
 147         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 148 #endif
 149 #ifdef DLT_PPP_ETHER
 150         { pppoe_if_print,       DLT_PPP_ETHER },
 151 #endif
 152 #ifdef DLT_LINUX_SLL
 153         { sll_if_print,         DLT_LINUX_SLL },
 154 #endif
 155 #ifdef DLT_IEEE802_11
 156         { ieee802_11_if_print,  DLT_IEEE802_11},
 157 #endif
 158 #ifdef DLT_LTALK
 159         { ltalk_if_print,       DLT_LTALK },
 160 #endif
 161         { NULL,                 0 },
 162 };
 163
 164 static pcap_handler
 165 lookup_printer(int type)
 166 {
 167         struct printer *p;
 168
 169         for (p = printers; p->f; ++p)
 170                 if (type == p->type)
 171                         return p->f;
 172
 173         error("unknown data link type %d", type);
 174         /* NOTREACHED */
 175 }
 176
 177 static pcap_t *pd;
 178
 179 extern int optind;
 180 extern int opterr;
 181 extern char *optarg;
 182
 183 struct dump_info {
 184         char    *WFileName;
 185         pcap_t  *pd;
 186         pcap_dumper_t *p;
 187 };
 188
 189 int
 190 main(int argc, char **argv)
 191 {
 192         register int cnt, op, i;
 193         bpf_u_int32 localnet, netmask;
 194         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 195         pcap_handler printer;
 196         struct bpf_program fcode;
 197         RETSIGTYPE (*oldhandler)(int);
 198         struct dump_info info;
 199         u_char *pcap_userdata;
 200         char ebuf[PCAP_ERRBUF_SIZE];
 201
 202         cnt = -1;
 203         device = NULL;
 204         infile = NULL;
 205         RFileName = NULL;
 206         WFileName = NULL;
 207         if ((cp = strrchr(argv[0], '/')) != NULL)
 208                 program_name = cp + 1;
 209         else
 210                 program_name = argv[0];
 211
 212         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 213                 error("%s", ebuf);
 214
 215 #ifdef LIBSMI
 216         smiInit("tcpdump");
 217 #endif
 218
 219         opterr = 0;
 220         while (
 221             (op = getopt(argc, argv, "ac:C:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 222                 switch (op) {
 223
 224                 case 'a':
 225                         ++aflag;
 226                         break;
 227
 228                 case 'c':
 229                         cnt = atoi(optarg);
 230                         if (cnt <= 0)
 231                                 error("invalid packet count %s", optarg);
 232                         break;
 233
 234                 case 'C':
 235                         Cflag = atoi(optarg) * 1000000;
 236                         if (Cflag < 0)
 237                                 error("invalid file size %s", optarg);
 238                         break;
 239
 240                 case 'd':
 241                         ++dflag;
 242                         break;
 243
 244                 case 'e':
 245                         ++eflag;
 246                         break;
 247
 248                 case 'E':
 249 #ifndef HAVE_LIBCRYPTO
 250                         warning("crypto code not compiled in");
 251 #endif
 252                         espsecret = optarg;
 253                         break;
 254
 255                 case 'f':
 256                         ++fflag;
 257                         break;
 258
 259                 case 'F':
 260                         infile = optarg;
 261                         break;
 262
 263                 case 'i':
 264                         device = optarg;
 265                         break;
 266
 267                 case 'l':
 268 #ifdef HAVE_SETLINEBUF
 269                         setlinebuf(stdout);
 270 #else
 271                         setvbuf(stdout, NULL, _IOLBF, 0);
 272 #endif
 273                         break;
 274
 275                 case 'n':
 276                         ++nflag;
 277                         break;
 278
 279                 case 'N':
 280                         ++Nflag;
 281                         break;
 282
 283                 case 'm':
 284 #ifdef LIBSMI
 285                         if (smiLoadModule(optarg) == 0) {
 286                                 error("could not load MIB module %s", optarg);
 287                         }
 288                         sflag = 1;
 289 #else
 290                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 291                                       program_name, optarg);
 292                         (void)fprintf(stderr, "(no libsmi support)\n");
 293 #endif
 294
 295                 case 'O':
 296                         Oflag = 0;
 297                         break;
 298
 299                 case 'p':
 300                         ++pflag;
 301                         break;
 302
 303                 case 'q':
 304                         ++qflag;
 305                         break;
 306
 307                 case 'r':
 308                         RFileName = optarg;
 309                         break;
 310
 311                 case 'R':
 312                         Rflag = 0;
 313                         break;
 314
 315                 case 's': {
 316                         char *end;
 317
 318                         snaplen = strtol(optarg, &end, 0);
 319                         if (optarg == end || *end != '\0'
 320                             || snaplen < 0 || snaplen > 65535)
 321                                 error("invalid snaplen %s", optarg);
 322                         else if (snaplen == 0)
 323                                 snaplen = 65535;
 324                         break;
 325                 }
 326
 327                 case 'S':
 328                         ++Sflag;
 329                         break;
 330
 331                 case 't':
 332                         --tflag;
 333                         break;
 334
 335                 case 'T':
 336                         if (strcasecmp(optarg, "vat") == 0)
 337                                 packettype = PT_VAT;
 338                         else if (strcasecmp(optarg, "wb") == 0)
 339                                 packettype = PT_WB;
 340                         else if (strcasecmp(optarg, "rpc") == 0)
 341                                 packettype = PT_RPC;
 342                         else if (strcasecmp(optarg, "rtp") == 0)
 343                                 packettype = PT_RTP;
 344                         else if (strcasecmp(optarg, "rtcp") == 0)
 345                                 packettype = PT_RTCP;
 346                         else if (strcasecmp(optarg, "snmp") == 0)
 347                                 packettype = PT_SNMP;
 348                         else if (strcasecmp(optarg, "cnfp") == 0)
 349                                 packettype = PT_CNFP;
 350                         else
 351                                 error("unknown packet type `%s'", optarg);
 352                         break;
 353
 354                 case 'u':
 355                         ++uflag;
 356                         break;
 357
 358                 case 'v':
 359                         ++vflag;
 360                         break;
 361
 362                 case 'w':
 363                         WFileName = optarg;
 364                         break;
 365
 366                 case 'x':
 367                         ++xflag;
 368                         break;
 369
 370                 case 'X':
 371                         ++xflag;
 372                         ++Xflag;
 373                         break;
 374
 375 #ifdef YYDEBUG
 376                 case 'Y':
 377                         {
 378                         /* Undocumented flag */
 379                         extern int yydebug;
 380                         yydebug = 1;
 381                         }
 382                         break;
 383 #endif
 384                 default:
 385                         usage();
 386                         /* NOTREACHED */
 387                 }
 388
 389         if (aflag && nflag)
 390                 error("-a and -n options are incompatible");
 391
 392         if (tflag > 0)
 393                 thiszone = gmt2local(0);
 394
 395         if (RFileName != NULL) {
 396                 /*
 397                  * We don't need network access, so set it back to the user id.
 398                  * Also, this prevents the user from reading anyone's
 399                  * trace file.
 400                  */
 401                 setuid(getuid());
 402
 403                 pd = pcap_open_offline(RFileName, ebuf);
 404                 if (pd == NULL)
 405                         error("%s", ebuf);
 406                 localnet = 0;
 407                 netmask = 0;
 408                 if (fflag != 0)
 409                         error("-f and -r options are incompatible");
 410         } else {
 411                 if (device == NULL) {
 412                         device = pcap_lookupdev(ebuf);
 413                         if (device == NULL)
 414                                 error("%s", ebuf);
 415                 }
 416                 *ebuf = '\0';
 417                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 418                 if (pd == NULL)
 419                         error("%s", ebuf);
 420                 else if (*ebuf)
 421                         warning("%s", ebuf);
 422                 i = pcap_snapshot(pd);
 423                 if (snaplen < i) {
 424                         warning("snaplen raised from %d to %d", snaplen, i);
 425                         snaplen = i;
 426                 }
 427                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 428                         localnet = 0;
 429                         netmask = 0;
 430                         warning("%s", ebuf);
 431                 }
 432                 /*
 433                  * Let user own process after socket has been opened.
 434                  */
 435                 setuid(getuid());
 436         }
 437         if (infile)
 438                 cmdbuf = read_infile(infile);
 439         else
 440                 cmdbuf = copy_argv(&argv[optind]);
 441
 442         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 443                 error("%s", pcap_geterr(pd));
 444         if (dflag) {
 445                 bpf_dump(&fcode, dflag);
 446                 exit(0);
 447         }
 448         init_addrtoname(localnet, netmask);
 449
 450         (void)setsignal(SIGTERM, cleanup);
 451         (void)setsignal(SIGINT, cleanup);
 452         /* Cooperate with nohup(1) */
 453         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 454                 (void)setsignal(SIGHUP, oldhandler);
 455
 456         if (pcap_setfilter(pd, &fcode) < 0)
 457                 error("%s", pcap_geterr(pd));
 458         if (WFileName) {
 459                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 460                 if (p == NULL)
 461                         error("%s", pcap_geterr(pd));
 462                 if (Cflag != 0) {
 463                         printer = dump_and_trunc;
 464                         info.WFileName = WFileName;
 465                         info.pd = pd;
 466                         info.p = p;
 467                         pcap_userdata = (u_char *)&info;
 468                 } else {
 469                         printer = pcap_dump;
 470                         pcap_userdata = (u_char *)p;
 471                 }
 472         } else {
 473                 printer = lookup_printer(pcap_datalink(pd));
 474                 pcap_userdata = 0;
 475 #ifdef SIGINFO
 476                 (void)setsignal(SIGINFO, requestinfo);
 477 #endif
 478         }
 479         if (RFileName == NULL) {
 480                 (void)fprintf(stderr, "%s: listening on %s\n",
 481                     program_name, device);
 482                 (void)fflush(stderr);
 483         }
 484         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 485                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 486                     program_name, pcap_geterr(pd));
 487                 exit(1);
 488         }
 489         pcap_close(pd);
 490         exit(0);
 491 }
 492
 493 /* make a clean exit on interrupts */
 494 static RETSIGTYPE
 495 cleanup(int signo)
 496 {
 497
 498         /* Can't print the summary if reading from a savefile */
 499         if (pd != NULL && pcap_file(pd) == NULL) {
 500                 (void)fflush(stdout);
 501                 putc('\n', stderr);
 502                 info(1);
 503         }
 504         exit(0);
 505 }
 506
 507 void
 508 info(register int verbose)
 509 {
 510         struct pcap_stat stat;
 511
 512         if (pcap_stats(pd, &stat) < 0) {
 513                 (void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
 514                 return;
 515         }
 516         if (!verbose)
 517                 fprintf(stderr, "%s: ", program_name);
 518         (void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
 519         if (!verbose)
 520                 fputs(", ", stderr);
 521         else
 522                 putc('\n', stderr);
 523         (void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
 524         infoprint = 0;
 525 }
 526
 527 static void
 528 reverse(char *s)
 529 {
 530         int i, j, c;
 531
 532         for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
 533                 c = s[i];
 534                 s[i] = s[j];
 535                 s[j] = c;
 536         }
 537 }
 538
 539
 540 static void
 541 swebitoa(unsigned int n, char *s)
 542 {
 543         unsigned int i;
 544
 545         i = 0;
 546         do {
 547                 s[i++] = n % 10 + '0';
 548         } while ((n /= 10) > 0);
 549
 550         s[i] = '\0';
 551         reverse(s);
 552 }
 553
 554 static void
 555 dump_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 556 {
 557         struct dump_info *info;
 558         static uint cnt = 2;
 559         char *name;
 560
 561         info = (struct dump_info *)user;
 562
 563         /*
 564          * XXX - this won't prevent capture files from getting
 565          * larger than Cflag - the last packet written to the
 566          * file could put it over Cflag.
 567          */
 568         if (ftell((FILE *)info->p) > Cflag) {
 569                 name = (char *) malloc(strlen(info->WFileName) + 4);
 570                 if (name == NULL)
 571                         error("dump_and_trunc: malloc");
 572                 strcpy(name, info->WFileName);
 573                 swebitoa(cnt, name + strlen(info->WFileName));
 574                 cnt++;
 575                 pcap_dump_close(info->p);
 576                 info->p = pcap_dump_open(info->pd, name);
 577                 free(name);
 578                 if (info->p == NULL)
 579                         error("%s", pcap_geterr(pd));
 580         }
 581
 582         pcap_dump((u_char *)info->p, h, sp);
 583 }
 584
 585 /* Like default_print() but data need not be aligned */
 586 void
 587 default_print_unaligned(register const u_char *cp, register u_int length)
 588 {
 589         register u_int i, s;
 590         register int nshorts;
 591
 592         if (Xflag) {
 593                 ascii_print(cp, length);
 594                 return;
 595         }
 596         nshorts = (u_int) length / sizeof(u_short);
 597         i = 0;
 598         while (--nshorts >= 0) {
 599                 if ((i++ % 8) == 0)
 600                         (void)printf("\n\t\t\t");
 601                 s = *cp++;
 602                 (void)printf(" %02x%02x", s, *cp++);
 603         }
 604         if (length & 1) {
 605                 if ((i % 8) == 0)
 606                         (void)printf("\n\t\t\t");
 607                 (void)printf(" %02x", *cp);
 608         }
 609 }
 610
 611 /*
 612  * By default, print the packet out in hex.
 613  */
 614 void
 615 default_print(register const u_char *bp, register u_int length)
 616 {
 617         default_print_unaligned(bp, length);
 618 }
 619
 620 #ifdef SIGINFO
 621 RETSIGTYPE requestinfo(int signo)
 622 {
 623         if (infodelay)
 624                 ++infoprint;
 625         else
 626                 info(0);
 627 }
 628 #endif
 629
 630 static void
 631 usage(void)
 632 {
 633         extern char version[];
 634         extern char pcap_version[];
 635
 636         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 637         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 638         (void)fprintf(stderr,
 639 "Usage: %s [-adeflnNOpqRStuvxX] [ -c count ] [ -C file_size ]\n", program_name);
 640         (void)fprintf(stderr,
 641 "\t\t[ -F file ] [ -i interface ] [ -r file ] [ -s snaplen ]\n");
 642         (void)fprintf(stderr,
 643 "\t\t[ -T type ] [ -w file ] [ -E algo:secret ] [ expression ]\n");
 644         exit(1);
 645 }