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 1.157 2000-12-16 22:00:50 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 #ifdef DLT_ATM_CLIP
 111         { cip_if_print,         DLT_ATM_CLIP },
 112 #endif
 113         { sl_if_print,          DLT_SLIP },
 114         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 115         { ppp_if_print,         DLT_PPP },
 116         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 117         { fddi_if_print,        DLT_FDDI },
 118         { null_if_print,        DLT_NULL },
 119 #ifdef DLT_LOOP
 120         { null_if_print,        DLT_LOOP },
 121 #endif
 122         { raw_if_print,         DLT_RAW },
 123         { atm_if_print,         DLT_ATM_RFC1483 },
 124 #ifdef DLT_C_HDLC
 125         { chdlc_if_print,       DLT_C_HDLC },
 126 #endif
 127 #ifdef DLT_PPP_SERIAL
 128         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 129 #endif
 130         { NULL,                 0 },
 131 };
 132
 133 static pcap_handler
 134 lookup_printer(int type)
 135 {
 136         struct printer *p;
 137
 138         for (p = printers; p->f; ++p)
 139                 if (type == p->type)
 140                         return p->f;
 141
 142         error("unknown data link type %d", type);
 143         /* NOTREACHED */
 144 }
 145
 146 static pcap_t *pd;
 147
 148 extern int optind;
 149 extern int opterr;
 150 extern char *optarg;
 151
 152 int
 153 main(int argc, char **argv)
 154 {
 155         register int cnt, op, i;
 156         bpf_u_int32 localnet, netmask;
 157         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 158         pcap_handler printer;
 159         struct bpf_program fcode;
 160         RETSIGTYPE (*oldhandler)(int);
 161         u_char *pcap_userdata;
 162         char ebuf[PCAP_ERRBUF_SIZE];
 163
 164         cnt = -1;
 165         device = NULL;
 166         infile = NULL;
 167         RFileName = NULL;
 168         WFileName = NULL;
 169         if ((cp = strrchr(argv[0], '/')) != NULL)
 170                 program_name = cp + 1;
 171         else
 172                 program_name = argv[0];
 173
 174         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 175                 error("%s", ebuf);
 176
 177 #ifdef LIBSMI
 178         smiInit("tcpdump");
 179 #endif
 180
 181         opterr = 0;
 182         while (
 183             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 184                 switch (op) {
 185
 186                 case 'a':
 187                         ++aflag;
 188                         break;
 189
 190                 case 'c':
 191                         cnt = atoi(optarg);
 192                         if (cnt <= 0)
 193                                 error("invalid packet count %s", optarg);
 194                         break;
 195
 196                 case 'd':
 197                         ++dflag;
 198                         break;
 199
 200                 case 'e':
 201                         ++eflag;
 202                         break;
 203
 204                 case 'E':
 205 #ifndef HAVE_LIBCRYPTO
 206                         warning("crypto code not compiled in");
 207 #endif
 208                         espsecret = optarg;
 209                         break;
 210
 211                 case 'f':
 212                         ++fflag;
 213                         break;
 214
 215                 case 'F':
 216                         infile = optarg;
 217                         break;
 218
 219                 case 'i':
 220                         device = optarg;
 221                         break;
 222
 223                 case 'l':
 224 #ifdef HAVE_SETLINEBUF
 225                         setlinebuf(stdout);
 226 #else
 227                         setvbuf(stdout, NULL, _IOLBF, 0);
 228 #endif
 229                         break;
 230
 231                 case 'n':
 232                         ++nflag;
 233                         break;
 234
 235                 case 'N':
 236                         ++Nflag;
 237                         break;
 238
 239                 case 'm':
 240 #ifdef LIBSMI
 241                         if (smiLoadModule(optarg) == 0) {
 242                                 error("could not load MIB module %s", optarg);
 243                         }
 244                         sflag = 1;
 245 #else
 246                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 247                                       program_name, optarg);
 248                         (void)fprintf(stderr, "(no libsmi support)\n");
 249 #endif
 250
 251                 case 'O':
 252                         Oflag = 0;
 253                         break;
 254
 255                 case 'p':
 256                         ++pflag;
 257                         break;
 258
 259                 case 'q':
 260                         ++qflag;
 261                         break;
 262
 263                 case 'r':
 264                         RFileName = optarg;
 265                         break;
 266
 267                 case 'R':
 268                         Rflag = 0;
 269                         break;
 270
 271                 case 's': {
 272                         char *end;
 273
 274                         snaplen = strtol(optarg, &end, 0);
 275                         if (optarg == end || *end != '\0'
 276                             || snaplen < 0 || snaplen > 65535)
 277                                 error("invalid snaplen %s", optarg);
 278                         else if (snaplen == 0)
 279                                 snaplen = 65535;
 280                         break;
 281                 }
 282
 283                 case 'S':
 284                         ++Sflag;
 285                         break;
 286
 287                 case 't':
 288                         --tflag;
 289                         break;
 290
 291                 case 'T':
 292                         if (strcasecmp(optarg, "vat") == 0)
 293                                 packettype = PT_VAT;
 294                         else if (strcasecmp(optarg, "wb") == 0)
 295                                 packettype = PT_WB;
 296                         else if (strcasecmp(optarg, "rpc") == 0)
 297                                 packettype = PT_RPC;
 298                         else if (strcasecmp(optarg, "rtp") == 0)
 299                                 packettype = PT_RTP;
 300                         else if (strcasecmp(optarg, "rtcp") == 0)
 301                                 packettype = PT_RTCP;
 302                         else if (strcasecmp(optarg, "snmp") == 0)
 303                                 packettype = PT_SNMP;
 304                         else if (strcasecmp(optarg, "cnfp") == 0)
 305                                 packettype = PT_CNFP;
 306                         else
 307                                 error("unknown packet type `%s'", optarg);
 308                         break;
 309
 310                 case 'u':
 311                         ++uflag;
 312                         break;
 313
 314                 case 'v':
 315                         ++vflag;
 316                         break;
 317
 318                 case 'w':
 319                         WFileName = optarg;
 320                         break;
 321
 322                 case 'x':
 323                         ++xflag;
 324                         break;
 325
 326                 case 'X':
 327                         ++xflag;
 328                         ++Xflag;
 329                         break;
 330
 331 #ifdef YYDEBUG
 332                 case 'Y':
 333                         {
 334                         /* Undocumented flag */
 335                         extern int yydebug;
 336                         yydebug = 1;
 337                         }
 338                         break;
 339 #endif
 340                 default:
 341                         usage();
 342                         /* NOTREACHED */
 343                 }
 344
 345         if (aflag && nflag)
 346                 error("-a and -n options are incompatible");
 347
 348         if (tflag > 0)
 349                 thiszone = gmt2local(0);
 350
 351         if (RFileName != NULL) {
 352                 /*
 353                  * We don't need network access, so set it back to the user id.
 354                  * Also, this prevents the user from reading anyone's
 355                  * trace file.
 356                  */
 357                 setuid(getuid());
 358
 359                 pd = pcap_open_offline(RFileName, ebuf);
 360                 if (pd == NULL)
 361                         error("%s", ebuf);
 362                 localnet = 0;
 363                 netmask = 0;
 364                 if (fflag != 0)
 365                         error("-f and -r options are incompatible");
 366         } else {
 367                 if (device == NULL) {
 368                         device = pcap_lookupdev(ebuf);
 369                         if (device == NULL)
 370                                 error("%s", ebuf);
 371                 }
 372                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 373                 if (pd == NULL)
 374                         error("%s", ebuf);
 375                 i = pcap_snapshot(pd);
 376                 if (snaplen < i) {
 377                         warning("snaplen raised from %d to %d", snaplen, i);
 378                         snaplen = i;
 379                 }
 380                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 381                         localnet = 0;
 382                         netmask = 0;
 383                         warning("%s", ebuf);
 384                 }
 385                 /*
 386                  * Let user own process after socket has been opened.
 387                  */
 388                 setuid(getuid());
 389         }
 390         if (infile)
 391                 cmdbuf = read_infile(infile);
 392         else
 393                 cmdbuf = copy_argv(&argv[optind]);
 394
 395         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 396                 error("%s", pcap_geterr(pd));
 397         if (dflag) {
 398                 bpf_dump(&fcode, dflag);
 399                 exit(0);
 400         }
 401         init_addrtoname(localnet, netmask);
 402
 403         (void)setsignal(SIGTERM, cleanup);
 404         (void)setsignal(SIGINT, cleanup);
 405         /* Cooperate with nohup(1) */
 406         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 407                 (void)setsignal(SIGHUP, oldhandler);
 408
 409         if (pcap_setfilter(pd, &fcode) < 0)
 410                 error("%s", pcap_geterr(pd));
 411         if (WFileName) {
 412                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 413                 if (p == NULL)
 414                         error("%s", pcap_geterr(pd));
 415                 printer = pcap_dump;
 416                 pcap_userdata = (u_char *)p;
 417         } else {
 418                 printer = lookup_printer(pcap_datalink(pd));
 419                 pcap_userdata = 0;
 420         }
 421         if (RFileName == NULL) {
 422                 (void)fprintf(stderr, "%s: listening on %s\n",
 423                     program_name, device);
 424                 (void)fflush(stderr);
 425         }
 426         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 427                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 428                     program_name, pcap_geterr(pd));
 429                 exit(1);
 430         }
 431         pcap_close(pd);
 432         exit(0);
 433 }
 434
 435 /* make a clean exit on interrupts */
 436 static RETSIGTYPE
 437 cleanup(int signo)
 438 {
 439         struct pcap_stat stat;
 440
 441         /* Can't print the summary if reading from a savefile */
 442         if (pd != NULL && pcap_file(pd) == NULL) {
 443                 (void)fflush(stdout);
 444                 putc('\n', stderr);
 445                 if (pcap_stats(pd, &stat) < 0)
 446                         (void)fprintf(stderr, "pcap_stats: %s\n",
 447                             pcap_geterr(pd));
 448                 else {
 449                         (void)fprintf(stderr, "%d packets received by filter\n",
 450                             stat.ps_recv);
 451                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 452                             stat.ps_drop);
 453                 }
 454         }
 455         exit(0);
 456 }
 457
 458 /* Like default_print() but data need not be aligned */
 459 void
 460 default_print_unaligned(register const u_char *cp, register u_int length)
 461 {
 462         register u_int i, s;
 463         register int nshorts;
 464
 465         if (Xflag) {
 466                 ascii_print(cp, length);
 467                 return;
 468         }
 469         nshorts = (u_int) length / sizeof(u_short);
 470         i = 0;
 471         while (--nshorts >= 0) {
 472                 if ((i++ % 8) == 0)
 473                         (void)printf("\n\t\t\t");
 474                 s = *cp++;
 475                 (void)printf(" %02x%02x", s, *cp++);
 476         }
 477         if (length & 1) {
 478                 if ((i % 8) == 0)
 479                         (void)printf("\n\t\t\t");
 480                 (void)printf(" %02x", *cp);
 481         }
 482 }
 483
 484 /*
 485  * By default, print the packet out in hex.
 486  */
 487 void
 488 default_print(register const u_char *bp, register u_int length)
 489 {
 490         default_print_unaligned(bp, length);
 491 }
 492
 493 static void
 494 usage(void)
 495 {
 496         extern char version[];
 497         extern char pcap_version[];
 498
 499         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 500         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 501         (void)fprintf(stderr,
 502 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 503         (void)fprintf(stderr,
 504 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 505         (void)fprintf(stderr,
 506 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 507         exit(-1);
 508 }