The Tcpdump Group git mirrors - tcpdump/blob - tcpdump.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 copyright[] =
  24     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997\n\
  25 The Regents of the University of California.  All rights reserved.\n";
  26 static const char rcsid[] =
  27     "@(#) $Header: /tcpdump/master/tcpdump/tcpdump.c,v 1.152 2000-09-18 05:11:44 guy Exp $ (LBL)";
  28 #endif
  29
  30 /*
  31  * tcpdump - monitor tcp/ip traffic on an ethernet.
  32  *
  33  * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory.
  34  * Mercilessly hacked and occasionally improved since then via the
  35  * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
  36  */
  37
  38 #ifdef HAVE_CONFIG_H
  39 #include "config.h"
  40 #endif
  41
  42 #include <sys/types.h>
  43 #include <sys/time.h>
  44
  45 #include <netinet/in.h>
  46
  47 #include <pcap.h>
  48 #include <signal.h>
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <string.h>
  52 #include <unistd.h>
  53 #include <ctype.h>
  54
  55 #include <netinet/in_systm.h>
  56 #include <netinet/ip.h>
  57
  58 #include "interface.h"
  59 #include "addrtoname.h"
  60 #include "machdep.h"
  61 #include "setsignal.h"
  62 #include "gmt2local.h"
  63
  64 int aflag;                      /* translate network and broadcast addresses */
  65 int dflag;                      /* print filter code */
  66 int eflag;                      /* print ethernet header */
  67 int fflag;                      /* don't translate "foreign" IP address */
  68 int nflag;                      /* leave addresses as numbers */
  69 int Nflag;                      /* remove domains from printed host names */
  70 int Oflag = 1;                  /* run filter code optimizer */
  71 int pflag;                      /* don't go promiscuous */
  72 int qflag;                      /* quick (shorter) output */
  73 int Rflag = 1;                  /* print sequence # field in AH/ESP*/
  74 int sflag = 0;                  /* use the libsmi to translate OIDs */
  75 int Sflag;                      /* print raw TCP sequence numbers */
  76 int tflag = 1;                  /* print packet arrival time */
  77 int uflag = 0;                  /* Print undecoded NFS handles */
  78 int vflag;                      /* verbose */
  79 int xflag;                      /* print packet in hex */
  80 int Xflag;                      /* print packet in ascii as well as hex */
  81
  82 char *espsecret = NULL;         /* ESP secret key */
  83
  84 int packettype;
  85
  86
  87 char *program_name;
  88
  89 int32_t thiszone;               /* seconds offset from gmt to local time */
  90
  91 /* Forwards */
  92 static RETSIGTYPE cleanup(int);
  93 static void usage(void) __attribute__((noreturn));
  94
  95 /* Length of saved portion of packet. */
  96 int snaplen = DEFAULT_SNAPLEN;
  97
  98 struct printer {
  99         pcap_handler f;
 100         int type;
 101 };
 102
 103 /*
 104  * This table checks some DLT_* codes as well as checking PCAP_ENCAP_*
 105  * codes, so that those DLT_* codes that aren't the same on all platforms
 106  * (and thus don't have values identical to the values of the corresponding
 107  * PCAP_ENCAP_* codes) are, at least, handled on the platform that wrote
 108  * the capture file.
 109  *
 110  * (This may result in two identical entries in the table, if there's
 111  * a DLT_* code defined to have the same value as the corresponding
 112  * PCAP_ENCAP_* code.  Those duplicate entries are harmless.)
 113  */
 114 static struct printer printers[] = {
 115         /*
 116          * PCAP_ENCAP_* codes that correspond to DLT_* codes whose values
 117          * are the same on all platforms (the PCAP_ENCAP_* code values
 118          * are the same as the DLT_* code values).
 119          */
 120         { null_if_print,        PCAP_ENCAP_NULL },
 121         { ether_if_print,       PCAP_ENCAP_ETHERNET },
 122         { token_if_print,       PCAP_ENCAP_TOKEN_RING },
 123         { sl_if_print,          PCAP_ENCAP_SLIP },
 124         { ppp_if_print,         PCAP_ENCAP_PPP },
 125         { fddi_if_print,        PCAP_ENCAP_FDDI },
 126
 127         /*
 128          * DLT_* codes that aren't the same on all platforms, or that
 129          * aren't present on all platforms.
 130          */
 131 #ifdef DLT_ATM_RFC1483
 132         { atm_if_print,         DLT_ATM_RFC1483 },
 133 #endif
 134 #ifdef DLT_RAW
 135         { raw_if_print,         DLT_RAW },
 136 #endif
 137 #ifdef DLT_SLIP_BSDOS
 138         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 139 #endif
 140 #ifdef DLT_PPP_BSDOS
 141         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 142 #endif
 143 #ifdef DLT_CIP
 144         { cip_if_print,         DLT_CIP },
 145 #endif
 146 #ifdef DLT_ATM_CLIP
 147         { cip_if_print,         DLT_ATM_CLIP },
 148 #endif
 149 #ifdef DLT_LANE8023
 150         { lane_if_print,        DLT_LANE8023 },
 151 #endif
 152 #ifdef DLT_PPP_SERIAL
 153         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 154 #endif
 155
 156         /*
 157          * PCAP_ENCAP_* codes corresponding to DLT_* codes that aren't
 158          * necessarily the same on all platforms, and PCAP_ENCAP_* codes
 159          * for which there aren't DLT_* codes.
 160          */
 161         { atm_if_print,         PCAP_ENCAP_ATM_RFC1483 },
 162         { raw_if_print,         PCAP_ENCAP_RAW },
 163         { sl_bsdos_if_print,    PCAP_ENCAP_SLIP_BSDOS },
 164         { ppp_bsdos_if_print,   PCAP_ENCAP_PPP_BSDOS },
 165         { chdlc_if_print,       PCAP_ENCAP_C_HDLC },
 166         { cip_if_print,         PCAP_ENCAP_ATM_CLIP },
 167         { ppp_hdlc_if_print,    PCAP_ENCAP_PPP_HDLC },
 168         { NULL,                 0 },
 169 };
 170
 171 static pcap_handler
 172 lookup_printer(int type)
 173 {
 174         struct printer *p;
 175
 176         for (p = printers; p->f; ++p)
 177                 if (type == p->type)
 178                         return p->f;
 179
 180         error("unknown data link type %d", type);
 181         /* NOTREACHED */
 182 }
 183
 184 static pcap_t *pd;
 185
 186 extern int optind;
 187 extern int opterr;
 188 extern char *optarg;
 189
 190 int
 191 main(int argc, char **argv)
 192 {
 193         register int cnt, op, i;
 194         bpf_u_int32 localnet, netmask;
 195         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 196         pcap_handler printer;
 197         struct bpf_program fcode;
 198         RETSIGTYPE (*oldhandler)(int);
 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: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 'd':
 235                         ++dflag;
 236                         break;
 237
 238                 case 'e':
 239                         ++eflag;
 240                         break;
 241
 242                 case 'E':
 243 #ifndef HAVE_LIBCRYPTO
 244                         warning("crypto code not compiled in");
 245 #endif
 246                         espsecret = optarg;
 247                         break;
 248
 249                 case 'f':
 250                         ++fflag;
 251                         break;
 252
 253                 case 'F':
 254                         infile = optarg;
 255                         break;
 256
 257                 case 'i':
 258                         device = optarg;
 259                         break;
 260
 261                 case 'l':
 262 #ifdef HAVE_SETLINEBUF
 263                         setlinebuf(stdout);
 264 #else
 265                         setvbuf(stdout, NULL, _IOLBF, 0);
 266 #endif
 267                         break;
 268
 269                 case 'n':
 270                         ++nflag;
 271                         break;
 272
 273                 case 'N':
 274                         ++Nflag;
 275                         break;
 276
 277                 case 'm':
 278 #ifdef LIBSMI
 279                         if (smiLoadModule(optarg) == 0) {
 280                                 error("could not load MIB module %s", optarg);
 281                         }
 282                         sflag = 1;
 283 #else
 284                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 285                                       program_name, optarg);
 286                         (void)fprintf(stderr, "(no libsmi support)\n");
 287 #endif
 288
 289                 case 'O':
 290                         Oflag = 0;
 291                         break;
 292
 293                 case 'p':
 294                         ++pflag;
 295                         break;
 296
 297                 case 'q':
 298                         ++qflag;
 299                         break;
 300
 301                 case 'r':
 302                         RFileName = optarg;
 303                         break;
 304
 305                 case 'R':
 306                         Rflag = 0;
 307                         break;
 308
 309                 case 's': {
 310                         char *end;
 311
 312                         snaplen = strtol(optarg, &end, 0);
 313                         if (optarg == end || *end != '\0'
 314                             || snaplen < 0 || snaplen > 65535)
 315                                 error("invalid snaplen %s", optarg);
 316                         else if (snaplen == 0)
 317                                 snaplen = 65535;
 318                         break;
 319                 }
 320
 321                 case 'S':
 322                         ++Sflag;
 323                         break;
 324
 325                 case 't':
 326                         --tflag;
 327                         break;
 328
 329                 case 'T':
 330                         if (strcasecmp(optarg, "vat") == 0)
 331                                 packettype = PT_VAT;
 332                         else if (strcasecmp(optarg, "wb") == 0)
 333                                 packettype = PT_WB;
 334                         else if (strcasecmp(optarg, "rpc") == 0)
 335                                 packettype = PT_RPC;
 336                         else if (strcasecmp(optarg, "rtp") == 0)
 337                                 packettype = PT_RTP;
 338                         else if (strcasecmp(optarg, "rtcp") == 0)
 339                                 packettype = PT_RTCP;
 340                         else if (strcasecmp(optarg, "snmp") == 0)
 341                                 packettype = PT_SNMP;
 342                         else if (strcasecmp(optarg, "cnfp") == 0)
 343                                 packettype = PT_CNFP;
 344                         else
 345                                 error("unknown packet type `%s'", optarg);
 346                         break;
 347
 348                 case 'u':
 349                         ++uflag;
 350                         break;
 351
 352                 case 'v':
 353                         ++vflag;
 354                         break;
 355
 356                 case 'w':
 357                         WFileName = optarg;
 358                         break;
 359
 360                 case 'x':
 361                         ++xflag;
 362                         break;
 363
 364                 case 'X':
 365                         ++xflag;
 366                         ++Xflag;
 367                         break;
 368
 369 #ifdef YYDEBUG
 370                 case 'Y':
 371                         {
 372                         /* Undocumented flag */
 373                         extern int yydebug;
 374                         yydebug = 1;
 375                         }
 376                         break;
 377 #endif
 378                 default:
 379                         usage();
 380                         /* NOTREACHED */
 381                 }
 382
 383         if (aflag && nflag)
 384                 error("-a and -n options are incompatible");
 385
 386         if (tflag > 0)
 387                 thiszone = gmt2local(0);
 388
 389         if (RFileName != NULL) {
 390                 /*
 391                  * We don't need network access, so set it back to the user id.
 392                  * Also, this prevents the user from reading anyone's
 393                  * trace file.
 394                  */
 395                 setuid(getuid());
 396
 397                 pd = pcap_open_offline(RFileName, ebuf);
 398                 if (pd == NULL)
 399                         error("%s", ebuf);
 400                 localnet = 0;
 401                 netmask = 0;
 402                 if (fflag != 0)
 403                         error("-f and -r options are incompatible");
 404         } else {
 405                 if (device == NULL) {
 406                         device = pcap_lookupdev(ebuf);
 407                         if (device == NULL)
 408                                 error("%s", ebuf);
 409                 }
 410                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 411                 if (pd == NULL)
 412                         error("%s", ebuf);
 413                 i = pcap_snapshot(pd);
 414                 if (snaplen < i) {
 415                         warning("snaplen raised from %d to %d", snaplen, i);
 416                         snaplen = i;
 417                 }
 418                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 419                         localnet = 0;
 420                         netmask = 0;
 421                         warning("%s", ebuf);
 422                 }
 423                 /*
 424                  * Let user own process after socket has been opened.
 425                  */
 426                 setuid(getuid());
 427         }
 428         if (infile)
 429                 cmdbuf = read_infile(infile);
 430         else
 431                 cmdbuf = copy_argv(&argv[optind]);
 432
 433         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 434                 error("%s", pcap_geterr(pd));
 435         if (dflag) {
 436                 bpf_dump(&fcode, dflag);
 437                 exit(0);
 438         }
 439         init_addrtoname(localnet, netmask);
 440
 441         (void)setsignal(SIGTERM, cleanup);
 442         (void)setsignal(SIGINT, cleanup);
 443         /* Cooperate with nohup(1) */
 444         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 445                 (void)setsignal(SIGHUP, oldhandler);
 446
 447         if (pcap_setfilter(pd, &fcode) < 0)
 448                 error("%s", pcap_geterr(pd));
 449         if (WFileName) {
 450                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 451                 if (p == NULL)
 452                         error("%s", pcap_geterr(pd));
 453                 printer = pcap_dump;
 454                 pcap_userdata = (u_char *)p;
 455         } else {
 456                 printer = lookup_printer(pcap_datalink(pd));
 457                 pcap_userdata = 0;
 458         }
 459         if (RFileName == NULL) {
 460                 (void)fprintf(stderr, "%s: listening on %s\n",
 461                     program_name, device);
 462                 (void)fflush(stderr);
 463         }
 464         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 465                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 466                     program_name, pcap_geterr(pd));
 467                 exit(1);
 468         }
 469         pcap_close(pd);
 470         exit(0);
 471 }
 472
 473 /* make a clean exit on interrupts */
 474 static RETSIGTYPE
 475 cleanup(int signo)
 476 {
 477         struct pcap_stat stat;
 478
 479         /* Can't print the summary if reading from a savefile */
 480         if (pd != NULL && pcap_file(pd) == NULL) {
 481                 (void)fflush(stdout);
 482                 putc('\n', stderr);
 483                 if (pcap_stats(pd, &stat) < 0)
 484                         (void)fprintf(stderr, "pcap_stats: %s\n",
 485                             pcap_geterr(pd));
 486                 else {
 487                         (void)fprintf(stderr, "%d packets received by filter\n",
 488                             stat.ps_recv);
 489                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 490                             stat.ps_drop);
 491                 }
 492         }
 493         exit(0);
 494 }
 495
 496 /* Like default_print() but data need not be aligned */
 497 void
 498 default_print_unaligned(register const u_char *cp, register u_int length)
 499 {
 500         register u_int i, s;
 501         register int nshorts;
 502
 503         if (Xflag) {
 504                 ascii_print(cp, length);
 505                 return;
 506         }
 507         nshorts = (u_int) length / sizeof(u_short);
 508         i = 0;
 509         while (--nshorts >= 0) {
 510                 if ((i++ % 8) == 0)
 511                         (void)printf("\n\t\t\t");
 512                 s = *cp++;
 513                 (void)printf(" %02x%02x", s, *cp++);
 514         }
 515         if (length & 1) {
 516                 if ((i % 8) == 0)
 517                         (void)printf("\n\t\t\t");
 518                 (void)printf(" %02x", *cp);
 519         }
 520 }
 521
 522 /*
 523  * By default, print the packet out in hex.
 524  */
 525 void
 526 default_print(register const u_char *bp, register u_int length)
 527 {
 528         default_print_unaligned(bp, length);
 529 }
 530
 531 static void
 532 usage(void)
 533 {
 534         extern char version[];
 535         extern char pcap_version[];
 536
 537         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 538         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 539         (void)fprintf(stderr,
 540 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 541         (void)fprintf(stderr,
 542 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 543         (void)fprintf(stderr,
 544 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 545         exit(-1);
 546 }