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 1.163 2001-06-18 08:52:54 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         { arcnet_if_print,      DLT_ARCNET },
 103         { ether_if_print,       DLT_EN10MB },
 104         { token_if_print,       DLT_IEEE802 },
 105 #ifdef DLT_LANE8023
 106         { lane_if_print,        DLT_LANE8023 },
 107 #endif
 108 #ifdef DLT_CIP
 109         { cip_if_print,         DLT_CIP },
 110 #endif
 111 #ifdef DLT_ATM_CLIP
 112         { cip_if_print,         DLT_ATM_CLIP },
 113 #endif
 114         { sl_if_print,          DLT_SLIP },
 115         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 116         { ppp_if_print,         DLT_PPP },
 117         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 118         { fddi_if_print,        DLT_FDDI },
 119         { null_if_print,        DLT_NULL },
 120 #ifdef DLT_LOOP
 121         { null_if_print,        DLT_LOOP },
 122 #endif
 123         { raw_if_print,         DLT_RAW },
 124         { atm_if_print,         DLT_ATM_RFC1483 },
 125 #ifdef DLT_C_HDLC
 126         { chdlc_if_print,       DLT_C_HDLC },
 127 #endif
 128 #ifdef DLT_HDLC
 129         { chdlc_if_print,       DLT_HDLC },
 130 #endif
 131 #ifdef DLT_PPP_SERIAL
 132         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 133 #endif
 134 #ifdef DLT_LINUX_SLL
 135         { sll_if_print,         DLT_LINUX_SLL },
 136 #endif
 137 #ifdef DLT_IEEE802_11
 138         { ieee802_11_if_print,  DLT_IEEE802_11},
 139 #endif
 140 #ifdef DLT_LTALK
 141         { ltalk_if_print,       DLT_LTALK },
 142 #endif
 143         { NULL,                 0 },
 144 };
 145
 146 static pcap_handler
 147 lookup_printer(int type)
 148 {
 149         struct printer *p;
 150
 151         for (p = printers; p->f; ++p)
 152                 if (type == p->type)
 153                         return p->f;
 154
 155         error("unknown data link type %d", type);
 156         /* NOTREACHED */
 157 }
 158
 159 static pcap_t *pd;
 160
 161 extern int optind;
 162 extern int opterr;
 163 extern char *optarg;
 164
 165 int
 166 main(int argc, char **argv)
 167 {
 168         register int cnt, op, i;
 169         bpf_u_int32 localnet, netmask;
 170         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 171         pcap_handler printer;
 172         struct bpf_program fcode;
 173         RETSIGTYPE (*oldhandler)(int);
 174         u_char *pcap_userdata;
 175         char ebuf[PCAP_ERRBUF_SIZE];
 176
 177         cnt = -1;
 178         device = NULL;
 179         infile = NULL;
 180         RFileName = NULL;
 181         WFileName = NULL;
 182         if ((cp = strrchr(argv[0], '/')) != NULL)
 183                 program_name = cp + 1;
 184         else
 185                 program_name = argv[0];
 186
 187         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 188                 error("%s", ebuf);
 189
 190 #ifdef LIBSMI
 191         smiInit("tcpdump");
 192 #endif
 193
 194         opterr = 0;
 195         while (
 196             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 197                 switch (op) {
 198
 199                 case 'a':
 200                         ++aflag;
 201                         break;
 202
 203                 case 'c':
 204                         cnt = atoi(optarg);
 205                         if (cnt <= 0)
 206                                 error("invalid packet count %s", optarg);
 207                         break;
 208
 209                 case 'd':
 210                         ++dflag;
 211                         break;
 212
 213                 case 'e':
 214                         ++eflag;
 215                         break;
 216
 217                 case 'E':
 218 #ifndef HAVE_LIBCRYPTO
 219                         warning("crypto code not compiled in");
 220 #endif
 221                         espsecret = optarg;
 222                         break;
 223
 224                 case 'f':
 225                         ++fflag;
 226                         break;
 227
 228                 case 'F':
 229                         infile = optarg;
 230                         break;
 231
 232                 case 'i':
 233                         device = optarg;
 234                         break;
 235
 236                 case 'l':
 237 #ifdef HAVE_SETLINEBUF
 238                         setlinebuf(stdout);
 239 #else
 240                         setvbuf(stdout, NULL, _IOLBF, 0);
 241 #endif
 242                         break;
 243
 244                 case 'n':
 245                         ++nflag;
 246                         break;
 247
 248                 case 'N':
 249                         ++Nflag;
 250                         break;
 251
 252                 case 'm':
 253 #ifdef LIBSMI
 254                         if (smiLoadModule(optarg) == 0) {
 255                                 error("could not load MIB module %s", optarg);
 256                         }
 257                         sflag = 1;
 258 #else
 259                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 260                                       program_name, optarg);
 261                         (void)fprintf(stderr, "(no libsmi support)\n");
 262 #endif
 263
 264                 case 'O':
 265                         Oflag = 0;
 266                         break;
 267
 268                 case 'p':
 269                         ++pflag;
 270                         break;
 271
 272                 case 'q':
 273                         ++qflag;
 274                         break;
 275
 276                 case 'r':
 277                         RFileName = optarg;
 278                         break;
 279
 280                 case 'R':
 281                         Rflag = 0;
 282                         break;
 283
 284                 case 's': {
 285                         char *end;
 286
 287                         snaplen = strtol(optarg, &end, 0);
 288                         if (optarg == end || *end != '\0'
 289                             || snaplen < 0 || snaplen > 65535)
 290                                 error("invalid snaplen %s", optarg);
 291                         else if (snaplen == 0)
 292                                 snaplen = 65535;
 293                         break;
 294                 }
 295
 296                 case 'S':
 297                         ++Sflag;
 298                         break;
 299
 300                 case 't':
 301                         --tflag;
 302                         break;
 303
 304                 case 'T':
 305                         if (strcasecmp(optarg, "vat") == 0)
 306                                 packettype = PT_VAT;
 307                         else if (strcasecmp(optarg, "wb") == 0)
 308                                 packettype = PT_WB;
 309                         else if (strcasecmp(optarg, "rpc") == 0)
 310                                 packettype = PT_RPC;
 311                         else if (strcasecmp(optarg, "rtp") == 0)
 312                                 packettype = PT_RTP;
 313                         else if (strcasecmp(optarg, "rtcp") == 0)
 314                                 packettype = PT_RTCP;
 315                         else if (strcasecmp(optarg, "snmp") == 0)
 316                                 packettype = PT_SNMP;
 317                         else if (strcasecmp(optarg, "cnfp") == 0)
 318                                 packettype = PT_CNFP;
 319                         else
 320                                 error("unknown packet type `%s'", optarg);
 321                         break;
 322
 323                 case 'u':
 324                         ++uflag;
 325                         break;
 326
 327                 case 'v':
 328                         ++vflag;
 329                         break;
 330
 331                 case 'w':
 332                         WFileName = optarg;
 333                         break;
 334
 335                 case 'x':
 336                         ++xflag;
 337                         break;
 338
 339                 case 'X':
 340                         ++xflag;
 341                         ++Xflag;
 342                         break;
 343
 344 #ifdef YYDEBUG
 345                 case 'Y':
 346                         {
 347                         /* Undocumented flag */
 348                         extern int yydebug;
 349                         yydebug = 1;
 350                         }
 351                         break;
 352 #endif
 353                 default:
 354                         usage();
 355                         /* NOTREACHED */
 356                 }
 357
 358         if (aflag && nflag)
 359                 error("-a and -n options are incompatible");
 360
 361         if (tflag > 0)
 362                 thiszone = gmt2local(0);
 363
 364         if (RFileName != NULL) {
 365                 /*
 366                  * We don't need network access, so set it back to the user id.
 367                  * Also, this prevents the user from reading anyone's
 368                  * trace file.
 369                  */
 370                 setuid(getuid());
 371
 372                 pd = pcap_open_offline(RFileName, ebuf);
 373                 if (pd == NULL)
 374                         error("%s", ebuf);
 375                 localnet = 0;
 376                 netmask = 0;
 377                 if (fflag != 0)
 378                         error("-f and -r options are incompatible");
 379         } else {
 380                 if (device == NULL) {
 381                         device = pcap_lookupdev(ebuf);
 382                         if (device == NULL)
 383                                 error("%s", ebuf);
 384                 }
 385                 *ebuf = '\0';
 386                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 387                 if (pd == NULL)
 388                         error("%s", ebuf);
 389                 else if (*ebuf)
 390                         warning("%s", ebuf);
 391                 i = pcap_snapshot(pd);
 392                 if (snaplen < i) {
 393                         warning("snaplen raised from %d to %d", snaplen, i);
 394                         snaplen = i;
 395                 }
 396                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 397                         localnet = 0;
 398                         netmask = 0;
 399                         warning("%s", ebuf);
 400                 }
 401                 /*
 402                  * Let user own process after socket has been opened.
 403                  */
 404                 setuid(getuid());
 405         }
 406         if (infile)
 407                 cmdbuf = read_infile(infile);
 408         else
 409                 cmdbuf = copy_argv(&argv[optind]);
 410
 411         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 412                 error("%s", pcap_geterr(pd));
 413         if (dflag) {
 414                 bpf_dump(&fcode, dflag);
 415                 exit(0);
 416         }
 417         init_addrtoname(localnet, netmask);
 418
 419         (void)setsignal(SIGTERM, cleanup);
 420         (void)setsignal(SIGINT, cleanup);
 421         /* Cooperate with nohup(1) */
 422         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 423                 (void)setsignal(SIGHUP, oldhandler);
 424
 425         if (pcap_setfilter(pd, &fcode) < 0)
 426                 error("%s", pcap_geterr(pd));
 427         if (WFileName) {
 428                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 429                 if (p == NULL)
 430                         error("%s", pcap_geterr(pd));
 431                 printer = pcap_dump;
 432                 pcap_userdata = (u_char *)p;
 433         } else {
 434                 printer = lookup_printer(pcap_datalink(pd));
 435                 pcap_userdata = 0;
 436         }
 437         if (RFileName == NULL) {
 438                 (void)fprintf(stderr, "%s: listening on %s\n",
 439                     program_name, device);
 440                 (void)fflush(stderr);
 441         }
 442         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 443                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 444                     program_name, pcap_geterr(pd));
 445                 exit(1);
 446         }
 447         pcap_close(pd);
 448         exit(0);
 449 }
 450
 451 /* make a clean exit on interrupts */
 452 static RETSIGTYPE
 453 cleanup(int signo)
 454 {
 455         struct pcap_stat stat;
 456
 457         /* Can't print the summary if reading from a savefile */
 458         if (pd != NULL && pcap_file(pd) == NULL) {
 459                 (void)fflush(stdout);
 460                 putc('\n', stderr);
 461                 if (pcap_stats(pd, &stat) < 0)
 462                         (void)fprintf(stderr, "pcap_stats: %s\n",
 463                             pcap_geterr(pd));
 464                 else {
 465                         (void)fprintf(stderr, "%d packets received by filter\n",
 466                             stat.ps_recv);
 467                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 468                             stat.ps_drop);
 469                 }
 470         }
 471         exit(0);
 472 }
 473
 474 /* Like default_print() but data need not be aligned */
 475 void
 476 default_print_unaligned(register const u_char *cp, register u_int length)
 477 {
 478         register u_int i, s;
 479         register int nshorts;
 480
 481         if (Xflag) {
 482                 ascii_print(cp, length);
 483                 return;
 484         }
 485         nshorts = (u_int) length / sizeof(u_short);
 486         i = 0;
 487         while (--nshorts >= 0) {
 488                 if ((i++ % 8) == 0)
 489                         (void)printf("\n\t\t\t");
 490                 s = *cp++;
 491                 (void)printf(" %02x%02x", s, *cp++);
 492         }
 493         if (length & 1) {
 494                 if ((i % 8) == 0)
 495                         (void)printf("\n\t\t\t");
 496                 (void)printf(" %02x", *cp);
 497         }
 498 }
 499
 500 /*
 501  * By default, print the packet out in hex.
 502  */
 503 void
 504 default_print(register const u_char *bp, register u_int length)
 505 {
 506         default_print_unaligned(bp, length);
 507 }
 508
 509 static void
 510 usage(void)
 511 {
 512         extern char version[];
 513         extern char pcap_version[];
 514
 515         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 516         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 517         (void)fprintf(stderr,
 518 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 519         (void)fprintf(stderr,
 520 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 521         (void)fprintf(stderr,
 522 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 523         exit(-1);
 524 }