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 1.155 2000-10-12 03:57:13 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
  56 #include "interface.h"
  57 #include "addrtoname.h"
  58 #include "machdep.h"
  59 #include "setsignal.h"
  60 #include "gmt2local.h"
  61
  62 int aflag;                      /* translate network and broadcast addresses */
  63 int dflag;                      /* print filter code */
  64 int eflag;                      /* print ethernet header */
  65 int fflag;                      /* don't translate "foreign" IP address */
  66 int nflag;                      /* leave addresses as numbers */
  67 int Nflag;                      /* remove domains from printed host names */
  68 int Oflag = 1;                  /* run filter code optimizer */
  69 int pflag;                      /* don't go promiscuous */
  70 int qflag;                      /* quick (shorter) output */
  71 int Rflag = 1;                  /* print sequence # field in AH/ESP*/
  72 int sflag = 0;                  /* use the libsmi to translate OIDs */
  73 int Sflag;                      /* print raw TCP sequence numbers */
  74 int tflag = 1;                  /* print packet arrival time */
  75 int uflag = 0;                  /* Print undecoded NFS handles */
  76 int vflag;                      /* verbose */
  77 int xflag;                      /* print packet in hex */
  78 int Xflag;                      /* print packet in ascii as well as hex */
  79
  80 char *espsecret = NULL;         /* ESP secret key */
  81
  82 int packettype;
  83
  84
  85 char *program_name;
  86
  87 int32_t thiszone;               /* seconds offset from gmt to local time */
  88
  89 /* Forwards */
  90 static RETSIGTYPE cleanup(int);
  91 static void usage(void) __attribute__((noreturn));
  92
  93 /* Length of saved portion of packet. */
  94 int snaplen = DEFAULT_SNAPLEN;
  95
  96 struct printer {
  97         pcap_handler f;
  98         int type;
  99 };
 100
 101 static struct printer printers[] = {
 102         { ether_if_print,       DLT_EN10MB },
 103         { token_if_print,       DLT_IEEE802 },
 104 #ifdef DLT_LANE8023
 105         { lane_if_print,        DLT_LANE8023 },
 106 #endif
 107 #ifdef DLT_CIP
 108         { cip_if_print,         DLT_CIP },
 109 #endif
 110         { cip_if_print,         DLT_ATM_CLIP },
 111         { sl_if_print,          DLT_SLIP },
 112         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 113         { ppp_if_print,         DLT_PPP },
 114         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 115         { fddi_if_print,        DLT_FDDI },
 116         { null_if_print,        DLT_NULL },
 117         { raw_if_print,         DLT_RAW },
 118         { atm_if_print,         DLT_ATM_RFC1483 },
 119         { chdlc_if_print,       DLT_C_HDLC },
 120         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 121         { NULL,                 0 },
 122 };
 123
 124 static pcap_handler
 125 lookup_printer(int type)
 126 {
 127         struct printer *p;
 128
 129         for (p = printers; p->f; ++p)
 130                 if (type == p->type)
 131                         return p->f;
 132
 133         error("unknown data link type %d", type);
 134         /* NOTREACHED */
 135 }
 136
 137 static pcap_t *pd;
 138
 139 extern int optind;
 140 extern int opterr;
 141 extern char *optarg;
 142
 143 int
 144 main(int argc, char **argv)
 145 {
 146         register int cnt, op, i;
 147         bpf_u_int32 localnet, netmask;
 148         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 149         pcap_handler printer;
 150         struct bpf_program fcode;
 151         RETSIGTYPE (*oldhandler)(int);
 152         u_char *pcap_userdata;
 153         char ebuf[PCAP_ERRBUF_SIZE];
 154
 155         cnt = -1;
 156         device = NULL;
 157         infile = NULL;
 158         RFileName = NULL;
 159         WFileName = NULL;
 160         if ((cp = strrchr(argv[0], '/')) != NULL)
 161                 program_name = cp + 1;
 162         else
 163                 program_name = argv[0];
 164
 165         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 166                 error("%s", ebuf);
 167
 168 #ifdef LIBSMI
 169         smiInit("tcpdump");
 170 #endif
 171
 172         opterr = 0;
 173         while (
 174             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 175                 switch (op) {
 176
 177                 case 'a':
 178                         ++aflag;
 179                         break;
 180
 181                 case 'c':
 182                         cnt = atoi(optarg);
 183                         if (cnt <= 0)
 184                                 error("invalid packet count %s", optarg);
 185                         break;
 186
 187                 case 'd':
 188                         ++dflag;
 189                         break;
 190
 191                 case 'e':
 192                         ++eflag;
 193                         break;
 194
 195                 case 'E':
 196 #ifndef HAVE_LIBCRYPTO
 197                         warning("crypto code not compiled in");
 198 #endif
 199                         espsecret = optarg;
 200                         break;
 201
 202                 case 'f':
 203                         ++fflag;
 204                         break;
 205
 206                 case 'F':
 207                         infile = optarg;
 208                         break;
 209
 210                 case 'i':
 211                         device = optarg;
 212                         break;
 213
 214                 case 'l':
 215 #ifdef HAVE_SETLINEBUF
 216                         setlinebuf(stdout);
 217 #else
 218                         setvbuf(stdout, NULL, _IOLBF, 0);
 219 #endif
 220                         break;
 221
 222                 case 'n':
 223                         ++nflag;
 224                         break;
 225
 226                 case 'N':
 227                         ++Nflag;
 228                         break;
 229
 230                 case 'm':
 231 #ifdef LIBSMI
 232                         if (smiLoadModule(optarg) == 0) {
 233                                 error("could not load MIB module %s", optarg);
 234                         }
 235                         sflag = 1;
 236 #else
 237                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 238                                       program_name, optarg);
 239                         (void)fprintf(stderr, "(no libsmi support)\n");
 240 #endif
 241
 242                 case 'O':
 243                         Oflag = 0;
 244                         break;
 245
 246                 case 'p':
 247                         ++pflag;
 248                         break;
 249
 250                 case 'q':
 251                         ++qflag;
 252                         break;
 253
 254                 case 'r':
 255                         RFileName = optarg;
 256                         break;
 257
 258                 case 'R':
 259                         Rflag = 0;
 260                         break;
 261
 262                 case 's': {
 263                         char *end;
 264
 265                         snaplen = strtol(optarg, &end, 0);
 266                         if (optarg == end || *end != '\0'
 267                             || snaplen < 0 || snaplen > 65535)
 268                                 error("invalid snaplen %s", optarg);
 269                         else if (snaplen == 0)
 270                                 snaplen = 65535;
 271                         break;
 272                 }
 273
 274                 case 'S':
 275                         ++Sflag;
 276                         break;
 277
 278                 case 't':
 279                         --tflag;
 280                         break;
 281
 282                 case 'T':
 283                         if (strcasecmp(optarg, "vat") == 0)
 284                                 packettype = PT_VAT;
 285                         else if (strcasecmp(optarg, "wb") == 0)
 286                                 packettype = PT_WB;
 287                         else if (strcasecmp(optarg, "rpc") == 0)
 288                                 packettype = PT_RPC;
 289                         else if (strcasecmp(optarg, "rtp") == 0)
 290                                 packettype = PT_RTP;
 291                         else if (strcasecmp(optarg, "rtcp") == 0)
 292                                 packettype = PT_RTCP;
 293                         else if (strcasecmp(optarg, "snmp") == 0)
 294                                 packettype = PT_SNMP;
 295                         else if (strcasecmp(optarg, "cnfp") == 0)
 296                                 packettype = PT_CNFP;
 297                         else
 298                                 error("unknown packet type `%s'", optarg);
 299                         break;
 300
 301                 case 'u':
 302                         ++uflag;
 303                         break;
 304
 305                 case 'v':
 306                         ++vflag;
 307                         break;
 308
 309                 case 'w':
 310                         WFileName = optarg;
 311                         break;
 312
 313                 case 'x':
 314                         ++xflag;
 315                         break;
 316
 317                 case 'X':
 318                         ++xflag;
 319                         ++Xflag;
 320                         break;
 321
 322 #ifdef YYDEBUG
 323                 case 'Y':
 324                         {
 325                         /* Undocumented flag */
 326                         extern int yydebug;
 327                         yydebug = 1;
 328                         }
 329                         break;
 330 #endif
 331                 default:
 332                         usage();
 333                         /* NOTREACHED */
 334                 }
 335
 336         if (aflag && nflag)
 337                 error("-a and -n options are incompatible");
 338
 339         if (tflag > 0)
 340                 thiszone = gmt2local(0);
 341
 342         if (RFileName != NULL) {
 343                 /*
 344                  * We don't need network access, so set it back to the user id.
 345                  * Also, this prevents the user from reading anyone's
 346                  * trace file.
 347                  */
 348                 setuid(getuid());
 349
 350                 pd = pcap_open_offline(RFileName, ebuf);
 351                 if (pd == NULL)
 352                         error("%s", ebuf);
 353                 localnet = 0;
 354                 netmask = 0;
 355                 if (fflag != 0)
 356                         error("-f and -r options are incompatible");
 357         } else {
 358                 if (device == NULL) {
 359                         device = pcap_lookupdev(ebuf);
 360                         if (device == NULL)
 361                                 error("%s", ebuf);
 362                 }
 363                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 364                 if (pd == NULL)
 365                         error("%s", ebuf);
 366                 i = pcap_snapshot(pd);
 367                 if (snaplen < i) {
 368                         warning("snaplen raised from %d to %d", snaplen, i);
 369                         snaplen = i;
 370                 }
 371                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 372                         localnet = 0;
 373                         netmask = 0;
 374                         warning("%s", ebuf);
 375                 }
 376                 /*
 377                  * Let user own process after socket has been opened.
 378                  */
 379                 setuid(getuid());
 380         }
 381         if (infile)
 382                 cmdbuf = read_infile(infile);
 383         else
 384                 cmdbuf = copy_argv(&argv[optind]);
 385
 386         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 387                 error("%s", pcap_geterr(pd));
 388         if (dflag) {
 389                 bpf_dump(&fcode, dflag);
 390                 exit(0);
 391         }
 392         init_addrtoname(localnet, netmask);
 393
 394         (void)setsignal(SIGTERM, cleanup);
 395         (void)setsignal(SIGINT, cleanup);
 396         /* Cooperate with nohup(1) */
 397         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 398                 (void)setsignal(SIGHUP, oldhandler);
 399
 400         if (pcap_setfilter(pd, &fcode) < 0)
 401                 error("%s", pcap_geterr(pd));
 402         if (WFileName) {
 403                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 404                 if (p == NULL)
 405                         error("%s", pcap_geterr(pd));
 406                 printer = pcap_dump;
 407                 pcap_userdata = (u_char *)p;
 408         } else {
 409                 printer = lookup_printer(pcap_datalink(pd));
 410                 pcap_userdata = 0;
 411         }
 412         if (RFileName == NULL) {
 413                 (void)fprintf(stderr, "%s: listening on %s\n",
 414                     program_name, device);
 415                 (void)fflush(stderr);
 416         }
 417         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 418                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 419                     program_name, pcap_geterr(pd));
 420                 exit(1);
 421         }
 422         pcap_close(pd);
 423         exit(0);
 424 }
 425
 426 /* make a clean exit on interrupts */
 427 static RETSIGTYPE
 428 cleanup(int signo)
 429 {
 430         struct pcap_stat stat;
 431
 432         /* Can't print the summary if reading from a savefile */
 433         if (pd != NULL && pcap_file(pd) == NULL) {
 434                 (void)fflush(stdout);
 435                 putc('\n', stderr);
 436                 if (pcap_stats(pd, &stat) < 0)
 437                         (void)fprintf(stderr, "pcap_stats: %s\n",
 438                             pcap_geterr(pd));
 439                 else {
 440                         (void)fprintf(stderr, "%d packets received by filter\n",
 441                             stat.ps_recv);
 442                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 443                             stat.ps_drop);
 444                 }
 445         }
 446         exit(0);
 447 }
 448
 449 /* Like default_print() but data need not be aligned */
 450 void
 451 default_print_unaligned(register const u_char *cp, register u_int length)
 452 {
 453         register u_int i, s;
 454         register int nshorts;
 455
 456         if (Xflag) {
 457                 ascii_print(cp, length);
 458                 return;
 459         }
 460         nshorts = (u_int) length / sizeof(u_short);
 461         i = 0;
 462         while (--nshorts >= 0) {
 463                 if ((i++ % 8) == 0)
 464                         (void)printf("\n\t\t\t");
 465                 s = *cp++;
 466                 (void)printf(" %02x%02x", s, *cp++);
 467         }
 468         if (length & 1) {
 469                 if ((i % 8) == 0)
 470                         (void)printf("\n\t\t\t");
 471                 (void)printf(" %02x", *cp);
 472         }
 473 }
 474
 475 /*
 476  * By default, print the packet out in hex.
 477  */
 478 void
 479 default_print(register const u_char *bp, register u_int length)
 480 {
 481         default_print_unaligned(bp, length);
 482 }
 483
 484 static void
 485 usage(void)
 486 {
 487         extern char version[];
 488         extern char pcap_version[];
 489
 490         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 491         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 492         (void)fprintf(stderr,
 493 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 494         (void)fprintf(stderr,
 495 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 496         (void)fprintf(stderr,
 497 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 498         exit(-1);
 499 }