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 1.162 2001-06-12 05:17:18 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         { NULL,                 0 },
 141 };
 142
 143 static pcap_handler
 144 lookup_printer(int type)
 145 {
 146         struct printer *p;
 147
 148         for (p = printers; p->f; ++p)
 149                 if (type == p->type)
 150                         return p->f;
 151
 152         error("unknown data link type %d", type);
 153         /* NOTREACHED */
 154 }
 155
 156 static pcap_t *pd;
 157
 158 extern int optind;
 159 extern int opterr;
 160 extern char *optarg;
 161
 162 int
 163 main(int argc, char **argv)
 164 {
 165         register int cnt, op, i;
 166         bpf_u_int32 localnet, netmask;
 167         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 168         pcap_handler printer;
 169         struct bpf_program fcode;
 170         RETSIGTYPE (*oldhandler)(int);
 171         u_char *pcap_userdata;
 172         char ebuf[PCAP_ERRBUF_SIZE];
 173
 174         cnt = -1;
 175         device = NULL;
 176         infile = NULL;
 177         RFileName = NULL;
 178         WFileName = NULL;
 179         if ((cp = strrchr(argv[0], '/')) != NULL)
 180                 program_name = cp + 1;
 181         else
 182                 program_name = argv[0];
 183
 184         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 185                 error("%s", ebuf);
 186
 187 #ifdef LIBSMI
 188         smiInit("tcpdump");
 189 #endif
 190
 191         opterr = 0;
 192         while (
 193             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 194                 switch (op) {
 195
 196                 case 'a':
 197                         ++aflag;
 198                         break;
 199
 200                 case 'c':
 201                         cnt = atoi(optarg);
 202                         if (cnt <= 0)
 203                                 error("invalid packet count %s", optarg);
 204                         break;
 205
 206                 case 'd':
 207                         ++dflag;
 208                         break;
 209
 210                 case 'e':
 211                         ++eflag;
 212                         break;
 213
 214                 case 'E':
 215 #ifndef HAVE_LIBCRYPTO
 216                         warning("crypto code not compiled in");
 217 #endif
 218                         espsecret = optarg;
 219                         break;
 220
 221                 case 'f':
 222                         ++fflag;
 223                         break;
 224
 225                 case 'F':
 226                         infile = optarg;
 227                         break;
 228
 229                 case 'i':
 230                         device = optarg;
 231                         break;
 232
 233                 case 'l':
 234 #ifdef HAVE_SETLINEBUF
 235                         setlinebuf(stdout);
 236 #else
 237                         setvbuf(stdout, NULL, _IOLBF, 0);
 238 #endif
 239                         break;
 240
 241                 case 'n':
 242                         ++nflag;
 243                         break;
 244
 245                 case 'N':
 246                         ++Nflag;
 247                         break;
 248
 249                 case 'm':
 250 #ifdef LIBSMI
 251                         if (smiLoadModule(optarg) == 0) {
 252                                 error("could not load MIB module %s", optarg);
 253                         }
 254                         sflag = 1;
 255 #else
 256                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 257                                       program_name, optarg);
 258                         (void)fprintf(stderr, "(no libsmi support)\n");
 259 #endif
 260
 261                 case 'O':
 262                         Oflag = 0;
 263                         break;
 264
 265                 case 'p':
 266                         ++pflag;
 267                         break;
 268
 269                 case 'q':
 270                         ++qflag;
 271                         break;
 272
 273                 case 'r':
 274                         RFileName = optarg;
 275                         break;
 276
 277                 case 'R':
 278                         Rflag = 0;
 279                         break;
 280
 281                 case 's': {
 282                         char *end;
 283
 284                         snaplen = strtol(optarg, &end, 0);
 285                         if (optarg == end || *end != '\0'
 286                             || snaplen < 0 || snaplen > 65535)
 287                                 error("invalid snaplen %s", optarg);
 288                         else if (snaplen == 0)
 289                                 snaplen = 65535;
 290                         break;
 291                 }
 292
 293                 case 'S':
 294                         ++Sflag;
 295                         break;
 296
 297                 case 't':
 298                         --tflag;
 299                         break;
 300
 301                 case 'T':
 302                         if (strcasecmp(optarg, "vat") == 0)
 303                                 packettype = PT_VAT;
 304                         else if (strcasecmp(optarg, "wb") == 0)
 305                                 packettype = PT_WB;
 306                         else if (strcasecmp(optarg, "rpc") == 0)
 307                                 packettype = PT_RPC;
 308                         else if (strcasecmp(optarg, "rtp") == 0)
 309                                 packettype = PT_RTP;
 310                         else if (strcasecmp(optarg, "rtcp") == 0)
 311                                 packettype = PT_RTCP;
 312                         else if (strcasecmp(optarg, "snmp") == 0)
 313                                 packettype = PT_SNMP;
 314                         else if (strcasecmp(optarg, "cnfp") == 0)
 315                                 packettype = PT_CNFP;
 316                         else
 317                                 error("unknown packet type `%s'", optarg);
 318                         break;
 319
 320                 case 'u':
 321                         ++uflag;
 322                         break;
 323
 324                 case 'v':
 325                         ++vflag;
 326                         break;
 327
 328                 case 'w':
 329                         WFileName = optarg;
 330                         break;
 331
 332                 case 'x':
 333                         ++xflag;
 334                         break;
 335
 336                 case 'X':
 337                         ++xflag;
 338                         ++Xflag;
 339                         break;
 340
 341 #ifdef YYDEBUG
 342                 case 'Y':
 343                         {
 344                         /* Undocumented flag */
 345                         extern int yydebug;
 346                         yydebug = 1;
 347                         }
 348                         break;
 349 #endif
 350                 default:
 351                         usage();
 352                         /* NOTREACHED */
 353                 }
 354
 355         if (aflag && nflag)
 356                 error("-a and -n options are incompatible");
 357
 358         if (tflag > 0)
 359                 thiszone = gmt2local(0);
 360
 361         if (RFileName != NULL) {
 362                 /*
 363                  * We don't need network access, so set it back to the user id.
 364                  * Also, this prevents the user from reading anyone's
 365                  * trace file.
 366                  */
 367                 setuid(getuid());
 368
 369                 pd = pcap_open_offline(RFileName, ebuf);
 370                 if (pd == NULL)
 371                         error("%s", ebuf);
 372                 localnet = 0;
 373                 netmask = 0;
 374                 if (fflag != 0)
 375                         error("-f and -r options are incompatible");
 376         } else {
 377                 if (device == NULL) {
 378                         device = pcap_lookupdev(ebuf);
 379                         if (device == NULL)
 380                                 error("%s", ebuf);
 381                 }
 382                 *ebuf = '\0';
 383                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 384                 if (pd == NULL)
 385                         error("%s", ebuf);
 386                 else if (*ebuf)
 387                         warning("%s", ebuf);
 388                 i = pcap_snapshot(pd);
 389                 if (snaplen < i) {
 390                         warning("snaplen raised from %d to %d", snaplen, i);
 391                         snaplen = i;
 392                 }
 393                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 394                         localnet = 0;
 395                         netmask = 0;
 396                         warning("%s", ebuf);
 397                 }
 398                 /*
 399                  * Let user own process after socket has been opened.
 400                  */
 401                 setuid(getuid());
 402         }
 403         if (infile)
 404                 cmdbuf = read_infile(infile);
 405         else
 406                 cmdbuf = copy_argv(&argv[optind]);
 407
 408         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 409                 error("%s", pcap_geterr(pd));
 410         if (dflag) {
 411                 bpf_dump(&fcode, dflag);
 412                 exit(0);
 413         }
 414         init_addrtoname(localnet, netmask);
 415
 416         (void)setsignal(SIGTERM, cleanup);
 417         (void)setsignal(SIGINT, cleanup);
 418         /* Cooperate with nohup(1) */
 419         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 420                 (void)setsignal(SIGHUP, oldhandler);
 421
 422         if (pcap_setfilter(pd, &fcode) < 0)
 423                 error("%s", pcap_geterr(pd));
 424         if (WFileName) {
 425                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 426                 if (p == NULL)
 427                         error("%s", pcap_geterr(pd));
 428                 printer = pcap_dump;
 429                 pcap_userdata = (u_char *)p;
 430         } else {
 431                 printer = lookup_printer(pcap_datalink(pd));
 432                 pcap_userdata = 0;
 433         }
 434         if (RFileName == NULL) {
 435                 (void)fprintf(stderr, "%s: listening on %s\n",
 436                     program_name, device);
 437                 (void)fflush(stderr);
 438         }
 439         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 440                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 441                     program_name, pcap_geterr(pd));
 442                 exit(1);
 443         }
 444         pcap_close(pd);
 445         exit(0);
 446 }
 447
 448 /* make a clean exit on interrupts */
 449 static RETSIGTYPE
 450 cleanup(int signo)
 451 {
 452         struct pcap_stat stat;
 453
 454         /* Can't print the summary if reading from a savefile */
 455         if (pd != NULL && pcap_file(pd) == NULL) {
 456                 (void)fflush(stdout);
 457                 putc('\n', stderr);
 458                 if (pcap_stats(pd, &stat) < 0)
 459                         (void)fprintf(stderr, "pcap_stats: %s\n",
 460                             pcap_geterr(pd));
 461                 else {
 462                         (void)fprintf(stderr, "%d packets received by filter\n",
 463                             stat.ps_recv);
 464                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 465                             stat.ps_drop);
 466                 }
 467         }
 468         exit(0);
 469 }
 470
 471 /* Like default_print() but data need not be aligned */
 472 void
 473 default_print_unaligned(register const u_char *cp, register u_int length)
 474 {
 475         register u_int i, s;
 476         register int nshorts;
 477
 478         if (Xflag) {
 479                 ascii_print(cp, length);
 480                 return;
 481         }
 482         nshorts = (u_int) length / sizeof(u_short);
 483         i = 0;
 484         while (--nshorts >= 0) {
 485                 if ((i++ % 8) == 0)
 486                         (void)printf("\n\t\t\t");
 487                 s = *cp++;
 488                 (void)printf(" %02x%02x", s, *cp++);
 489         }
 490         if (length & 1) {
 491                 if ((i % 8) == 0)
 492                         (void)printf("\n\t\t\t");
 493                 (void)printf(" %02x", *cp);
 494         }
 495 }
 496
 497 /*
 498  * By default, print the packet out in hex.
 499  */
 500 void
 501 default_print(register const u_char *bp, register u_int length)
 502 {
 503         default_print_unaligned(bp, length);
 504 }
 505
 506 static void
 507 usage(void)
 508 {
 509         extern char version[];
 510         extern char pcap_version[];
 511
 512         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 513         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 514         (void)fprintf(stderr,
 515 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 516         (void)fprintf(stderr,
 517 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 518         (void)fprintf(stderr,
 519 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 520         exit(-1);
 521 }