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 1.164 2001-06-20 07:40:45 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_PPP_ETHER
 135         { pppoe_if_print,       DLT_PPP_ETHER },
 136 #endif
 137 #ifdef DLT_LINUX_SLL
 138         { sll_if_print,         DLT_LINUX_SLL },
 139 #endif
 140 #ifdef DLT_IEEE802_11
 141         { ieee802_11_if_print,  DLT_IEEE802_11},
 142 #endif
 143 #ifdef DLT_LTALK
 144         { ltalk_if_print,       DLT_LTALK },
 145 #endif
 146         { NULL,                 0 },
 147 };
 148
 149 static pcap_handler
 150 lookup_printer(int type)
 151 {
 152         struct printer *p;
 153
 154         for (p = printers; p->f; ++p)
 155                 if (type == p->type)
 156                         return p->f;
 157
 158         error("unknown data link type %d", type);
 159         /* NOTREACHED */
 160 }
 161
 162 static pcap_t *pd;
 163
 164 extern int optind;
 165 extern int opterr;
 166 extern char *optarg;
 167
 168 int
 169 main(int argc, char **argv)
 170 {
 171         register int cnt, op, i;
 172         bpf_u_int32 localnet, netmask;
 173         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 174         pcap_handler printer;
 175         struct bpf_program fcode;
 176         RETSIGTYPE (*oldhandler)(int);
 177         u_char *pcap_userdata;
 178         char ebuf[PCAP_ERRBUF_SIZE];
 179
 180         cnt = -1;
 181         device = NULL;
 182         infile = NULL;
 183         RFileName = NULL;
 184         WFileName = NULL;
 185         if ((cp = strrchr(argv[0], '/')) != NULL)
 186                 program_name = cp + 1;
 187         else
 188                 program_name = argv[0];
 189
 190         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 191                 error("%s", ebuf);
 192
 193 #ifdef LIBSMI
 194         smiInit("tcpdump");
 195 #endif
 196
 197         opterr = 0;
 198         while (
 199             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 200                 switch (op) {
 201
 202                 case 'a':
 203                         ++aflag;
 204                         break;
 205
 206                 case 'c':
 207                         cnt = atoi(optarg);
 208                         if (cnt <= 0)
 209                                 error("invalid packet count %s", optarg);
 210                         break;
 211
 212                 case 'd':
 213                         ++dflag;
 214                         break;
 215
 216                 case 'e':
 217                         ++eflag;
 218                         break;
 219
 220                 case 'E':
 221 #ifndef HAVE_LIBCRYPTO
 222                         warning("crypto code not compiled in");
 223 #endif
 224                         espsecret = optarg;
 225                         break;
 226
 227                 case 'f':
 228                         ++fflag;
 229                         break;
 230
 231                 case 'F':
 232                         infile = optarg;
 233                         break;
 234
 235                 case 'i':
 236                         device = optarg;
 237                         break;
 238
 239                 case 'l':
 240 #ifdef HAVE_SETLINEBUF
 241                         setlinebuf(stdout);
 242 #else
 243                         setvbuf(stdout, NULL, _IOLBF, 0);
 244 #endif
 245                         break;
 246
 247                 case 'n':
 248                         ++nflag;
 249                         break;
 250
 251                 case 'N':
 252                         ++Nflag;
 253                         break;
 254
 255                 case 'm':
 256 #ifdef LIBSMI
 257                         if (smiLoadModule(optarg) == 0) {
 258                                 error("could not load MIB module %s", optarg);
 259                         }
 260                         sflag = 1;
 261 #else
 262                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 263                                       program_name, optarg);
 264                         (void)fprintf(stderr, "(no libsmi support)\n");
 265 #endif
 266
 267                 case 'O':
 268                         Oflag = 0;
 269                         break;
 270
 271                 case 'p':
 272                         ++pflag;
 273                         break;
 274
 275                 case 'q':
 276                         ++qflag;
 277                         break;
 278
 279                 case 'r':
 280                         RFileName = optarg;
 281                         break;
 282
 283                 case 'R':
 284                         Rflag = 0;
 285                         break;
 286
 287                 case 's': {
 288                         char *end;
 289
 290                         snaplen = strtol(optarg, &end, 0);
 291                         if (optarg == end || *end != '\0'
 292                             || snaplen < 0 || snaplen > 65535)
 293                                 error("invalid snaplen %s", optarg);
 294                         else if (snaplen == 0)
 295                                 snaplen = 65535;
 296                         break;
 297                 }
 298
 299                 case 'S':
 300                         ++Sflag;
 301                         break;
 302
 303                 case 't':
 304                         --tflag;
 305                         break;
 306
 307                 case 'T':
 308                         if (strcasecmp(optarg, "vat") == 0)
 309                                 packettype = PT_VAT;
 310                         else if (strcasecmp(optarg, "wb") == 0)
 311                                 packettype = PT_WB;
 312                         else if (strcasecmp(optarg, "rpc") == 0)
 313                                 packettype = PT_RPC;
 314                         else if (strcasecmp(optarg, "rtp") == 0)
 315                                 packettype = PT_RTP;
 316                         else if (strcasecmp(optarg, "rtcp") == 0)
 317                                 packettype = PT_RTCP;
 318                         else if (strcasecmp(optarg, "snmp") == 0)
 319                                 packettype = PT_SNMP;
 320                         else if (strcasecmp(optarg, "cnfp") == 0)
 321                                 packettype = PT_CNFP;
 322                         else
 323                                 error("unknown packet type `%s'", optarg);
 324                         break;
 325
 326                 case 'u':
 327                         ++uflag;
 328                         break;
 329
 330                 case 'v':
 331                         ++vflag;
 332                         break;
 333
 334                 case 'w':
 335                         WFileName = optarg;
 336                         break;
 337
 338                 case 'x':
 339                         ++xflag;
 340                         break;
 341
 342                 case 'X':
 343                         ++xflag;
 344                         ++Xflag;
 345                         break;
 346
 347 #ifdef YYDEBUG
 348                 case 'Y':
 349                         {
 350                         /* Undocumented flag */
 351                         extern int yydebug;
 352                         yydebug = 1;
 353                         }
 354                         break;
 355 #endif
 356                 default:
 357                         usage();
 358                         /* NOTREACHED */
 359                 }
 360
 361         if (aflag && nflag)
 362                 error("-a and -n options are incompatible");
 363
 364         if (tflag > 0)
 365                 thiszone = gmt2local(0);
 366
 367         if (RFileName != NULL) {
 368                 /*
 369                  * We don't need network access, so set it back to the user id.
 370                  * Also, this prevents the user from reading anyone's
 371                  * trace file.
 372                  */
 373                 setuid(getuid());
 374
 375                 pd = pcap_open_offline(RFileName, ebuf);
 376                 if (pd == NULL)
 377                         error("%s", ebuf);
 378                 localnet = 0;
 379                 netmask = 0;
 380                 if (fflag != 0)
 381                         error("-f and -r options are incompatible");
 382         } else {
 383                 if (device == NULL) {
 384                         device = pcap_lookupdev(ebuf);
 385                         if (device == NULL)
 386                                 error("%s", ebuf);
 387                 }
 388                 *ebuf = '\0';
 389                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 390                 if (pd == NULL)
 391                         error("%s", ebuf);
 392                 else if (*ebuf)
 393                         warning("%s", ebuf);
 394                 i = pcap_snapshot(pd);
 395                 if (snaplen < i) {
 396                         warning("snaplen raised from %d to %d", snaplen, i);
 397                         snaplen = i;
 398                 }
 399                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 400                         localnet = 0;
 401                         netmask = 0;
 402                         warning("%s", ebuf);
 403                 }
 404                 /*
 405                  * Let user own process after socket has been opened.
 406                  */
 407                 setuid(getuid());
 408         }
 409         if (infile)
 410                 cmdbuf = read_infile(infile);
 411         else
 412                 cmdbuf = copy_argv(&argv[optind]);
 413
 414         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 415                 error("%s", pcap_geterr(pd));
 416         if (dflag) {
 417                 bpf_dump(&fcode, dflag);
 418                 exit(0);
 419         }
 420         init_addrtoname(localnet, netmask);
 421
 422         (void)setsignal(SIGTERM, cleanup);
 423         (void)setsignal(SIGINT, cleanup);
 424         /* Cooperate with nohup(1) */
 425         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 426                 (void)setsignal(SIGHUP, oldhandler);
 427
 428         if (pcap_setfilter(pd, &fcode) < 0)
 429                 error("%s", pcap_geterr(pd));
 430         if (WFileName) {
 431                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 432                 if (p == NULL)
 433                         error("%s", pcap_geterr(pd));
 434                 printer = pcap_dump;
 435                 pcap_userdata = (u_char *)p;
 436         } else {
 437                 printer = lookup_printer(pcap_datalink(pd));
 438                 pcap_userdata = 0;
 439         }
 440         if (RFileName == NULL) {
 441                 (void)fprintf(stderr, "%s: listening on %s\n",
 442                     program_name, device);
 443                 (void)fflush(stderr);
 444         }
 445         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 446                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 447                     program_name, pcap_geterr(pd));
 448                 exit(1);
 449         }
 450         pcap_close(pd);
 451         exit(0);
 452 }
 453
 454 /* make a clean exit on interrupts */
 455 static RETSIGTYPE
 456 cleanup(int signo)
 457 {
 458         struct pcap_stat stat;
 459
 460         /* Can't print the summary if reading from a savefile */
 461         if (pd != NULL && pcap_file(pd) == NULL) {
 462                 (void)fflush(stdout);
 463                 putc('\n', stderr);
 464                 if (pcap_stats(pd, &stat) < 0)
 465                         (void)fprintf(stderr, "pcap_stats: %s\n",
 466                             pcap_geterr(pd));
 467                 else {
 468                         (void)fprintf(stderr, "%d packets received by filter\n",
 469                             stat.ps_recv);
 470                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 471                             stat.ps_drop);
 472                 }
 473         }
 474         exit(0);
 475 }
 476
 477 /* Like default_print() but data need not be aligned */
 478 void
 479 default_print_unaligned(register const u_char *cp, register u_int length)
 480 {
 481         register u_int i, s;
 482         register int nshorts;
 483
 484         if (Xflag) {
 485                 ascii_print(cp, length);
 486                 return;
 487         }
 488         nshorts = (u_int) length / sizeof(u_short);
 489         i = 0;
 490         while (--nshorts >= 0) {
 491                 if ((i++ % 8) == 0)
 492                         (void)printf("\n\t\t\t");
 493                 s = *cp++;
 494                 (void)printf(" %02x%02x", s, *cp++);
 495         }
 496         if (length & 1) {
 497                 if ((i % 8) == 0)
 498                         (void)printf("\n\t\t\t");
 499                 (void)printf(" %02x", *cp);
 500         }
 501 }
 502
 503 /*
 504  * By default, print the packet out in hex.
 505  */
 506 void
 507 default_print(register const u_char *bp, register u_int length)
 508 {
 509         default_print_unaligned(bp, length);
 510 }
 511
 512 static void
 513 usage(void)
 514 {
 515         extern char version[];
 516         extern char pcap_version[];
 517
 518         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 519         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 520         (void)fprintf(stderr,
 521 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 522         (void)fprintf(stderr,
 523 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 524         (void)fprintf(stderr,
 525 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 526         exit(-1);
 527 }