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 1.151 2000-09-17 04:13:13 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 #include <netinet/in_systm.h>
  56 #include <netinet/ip.h>
  57
  58 #include "interface.h"
  59 #include "addrtoname.h"
  60 #include "machdep.h"
  61 #include "setsignal.h"
  62 #include "gmt2local.h"
  63
  64 int aflag;                      /* translate network and broadcast addresses */
  65 int dflag;                      /* print filter code */
  66 int eflag;                      /* print ethernet header */
  67 int fflag;                      /* don't translate "foreign" IP address */
  68 int nflag;                      /* leave addresses as numbers */
  69 int Nflag;                      /* remove domains from printed host names */
  70 int Oflag = 1;                  /* run filter code optimizer */
  71 int pflag;                      /* don't go promiscuous */
  72 int qflag;                      /* quick (shorter) output */
  73 int Rflag = 1;                  /* print sequence # field in AH/ESP*/
  74 int sflag = 0;                  /* use the libsmi to translate OIDs */
  75 int Sflag;                      /* print raw TCP sequence numbers */
  76 int tflag = 1;                  /* print packet arrival time */
  77 int uflag = 0;                  /* Print undecoded NFS handles */
  78 int vflag;                      /* verbose */
  79 int xflag;                      /* print packet in hex */
  80 int Xflag;                      /* print packet in ascii as well as hex */
  81
  82 char *espsecret = NULL;         /* ESP secret key */
  83
  84 int packettype;
  85
  86
  87 char *program_name;
  88
  89 int32_t thiszone;               /* seconds offset from gmt to local time */
  90
  91 /* Forwards */
  92 static RETSIGTYPE cleanup(int);
  93 static void usage(void) __attribute__((noreturn));
  94
  95 /* Length of saved portion of packet. */
  96 int snaplen = DEFAULT_SNAPLEN;
  97
  98 struct printer {
  99         pcap_handler f;
 100         int type;
 101 };
 102
 103 /*
 104  * This table checks some DLT_* codes as well as checking PCAP_ENCAP_*
 105  * codes, so that those DLT_* codes that aren't the same on all platforms
 106  * (and thus don't have values identical to the values of the corresponding
 107  * PCAP_ENCAP_* codes) are, at least, handled on the platform that wrote
 108  * the capture file.
 109  *
 110  * (This may result in two identical entries in the table, if there's
 111  * a DLT_* code defined to have the same value as the corresponding
 112  * PCAP_ENCAP_* code.  Those duplicate entries are harmless.)
 113  */
 114 static struct printer printers[] = {
 115         /*
 116          * PCAP_ENCAP_* codes that correspond to DLT_* codes whose values
 117          * are the same on all platforms (the PCAP_ENCAP_* code values
 118          * are the same as the DLT_* code values).
 119          */
 120         { null_if_print,        PCAP_ENCAP_NULL },
 121         { ether_if_print,       PCAP_ENCAP_ETHERNET },
 122         { token_if_print,       PCAP_ENCAP_TOKEN_RING },
 123         { sl_if_print,          PCAP_ENCAP_SLIP },
 124         { ppp_if_print,         PCAP_ENCAP_PPP },
 125         { fddi_if_print,        PCAP_ENCAP_FDDI },
 126
 127         /*
 128          * DLT_* codes that aren't the same on all platforms.
 129          */
 130 #ifdef DLT_ATM_RFC1483
 131         { atm_if_print,         DLT_ATM_RFC1483 },
 132 #endif
 133 #ifdef DLT_RAW
 134         { raw_if_print,         DLT_RAW },
 135 #endif
 136 #ifdef DLT_SLIP_BSDOS
 137         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 138 #endif
 139 #ifdef DLT_PPP_BSDOS
 140         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 141 #endif
 142 #ifdef DLT_CIP
 143         { cip_if_print,         DLT_CIP },
 144 #endif
 145 #ifdef DLT_ATM_CLIP
 146         { cip_if_print,         DLT_ATM_CLIP },
 147 #endif
 148 #ifdef DLT_LANE8023
 149         { lane_if_print,        DLT_LANE8023 },
 150 #endif
 151
 152         /*
 153          * PCAP_ENCAP_* codes corresponding to DLT_* codes that aren't
 154          * necessarily the same on all platforms, and PCAP_ENCAP_* codes
 155          * for which there aren't DLT_* codes.
 156          */
 157         { atm_if_print,         PCAP_ENCAP_ATM_RFC1483 },
 158         { raw_if_print,         PCAP_ENCAP_RAW },
 159         { sl_bsdos_if_print,    PCAP_ENCAP_SLIP_BSDOS },
 160         { ppp_bsdos_if_print,   PCAP_ENCAP_PPP_BSDOS },
 161         { chdlc_if_print,       PCAP_ENCAP_C_HDLC },
 162         { cip_if_print,         PCAP_ENCAP_ATM_CLIP },
 163         { NULL,                 0 },
 164 };
 165
 166 static pcap_handler
 167 lookup_printer(int type)
 168 {
 169         struct printer *p;
 170
 171         for (p = printers; p->f; ++p)
 172                 if (type == p->type)
 173                         return p->f;
 174
 175         error("unknown data link type %d", type);
 176         /* NOTREACHED */
 177 }
 178
 179 static pcap_t *pd;
 180
 181 extern int optind;
 182 extern int opterr;
 183 extern char *optarg;
 184
 185 int
 186 main(int argc, char **argv)
 187 {
 188         register int cnt, op, i;
 189         bpf_u_int32 localnet, netmask;
 190         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 191         pcap_handler printer;
 192         struct bpf_program fcode;
 193         RETSIGTYPE (*oldhandler)(int);
 194         u_char *pcap_userdata;
 195         char ebuf[PCAP_ERRBUF_SIZE];
 196
 197         cnt = -1;
 198         device = NULL;
 199         infile = NULL;
 200         RFileName = NULL;
 201         WFileName = NULL;
 202         if ((cp = strrchr(argv[0], '/')) != NULL)
 203                 program_name = cp + 1;
 204         else
 205                 program_name = argv[0];
 206
 207         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 208                 error("%s", ebuf);
 209
 210 #ifdef LIBSMI
 211         smiInit("tcpdump");
 212 #endif
 213
 214         opterr = 0;
 215         while (
 216             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 217                 switch (op) {
 218
 219                 case 'a':
 220                         ++aflag;
 221                         break;
 222
 223                 case 'c':
 224                         cnt = atoi(optarg);
 225                         if (cnt <= 0)
 226                                 error("invalid packet count %s", optarg);
 227                         break;
 228
 229                 case 'd':
 230                         ++dflag;
 231                         break;
 232
 233                 case 'e':
 234                         ++eflag;
 235                         break;
 236
 237                 case 'E':
 238 #ifndef HAVE_LIBCRYPTO
 239                         warning("crypto code not compiled in");
 240 #endif
 241                         espsecret = optarg;
 242                         break;
 243
 244                 case 'f':
 245                         ++fflag;
 246                         break;
 247
 248                 case 'F':
 249                         infile = optarg;
 250                         break;
 251
 252                 case 'i':
 253                         device = optarg;
 254                         break;
 255
 256                 case 'l':
 257 #ifdef HAVE_SETLINEBUF
 258                         setlinebuf(stdout);
 259 #else
 260                         setvbuf(stdout, NULL, _IOLBF, 0);
 261 #endif
 262                         break;
 263
 264                 case 'n':
 265                         ++nflag;
 266                         break;
 267
 268                 case 'N':
 269                         ++Nflag;
 270                         break;
 271
 272                 case 'm':
 273 #ifdef LIBSMI
 274                         if (smiLoadModule(optarg) == 0) {
 275                                 error("could not load MIB module %s", optarg);
 276                         }
 277                         sflag = 1;
 278 #else
 279                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 280                                       program_name, optarg);
 281                         (void)fprintf(stderr, "(no libsmi support)\n");
 282 #endif
 283
 284                 case 'O':
 285                         Oflag = 0;
 286                         break;
 287
 288                 case 'p':
 289                         ++pflag;
 290                         break;
 291
 292                 case 'q':
 293                         ++qflag;
 294                         break;
 295
 296                 case 'r':
 297                         RFileName = optarg;
 298                         break;
 299
 300                 case 'R':
 301                         Rflag = 0;
 302                         break;
 303
 304                 case 's': {
 305                         char *end;
 306
 307                         snaplen = strtol(optarg, &end, 0);
 308                         if (optarg == end || *end != '\0'
 309                             || snaplen < 0 || snaplen > 65535)
 310                                 error("invalid snaplen %s", optarg);
 311                         else if (snaplen == 0)
 312                                 snaplen = 65535;
 313                         break;
 314                 }
 315
 316                 case 'S':
 317                         ++Sflag;
 318                         break;
 319
 320                 case 't':
 321                         --tflag;
 322                         break;
 323
 324                 case 'T':
 325                         if (strcasecmp(optarg, "vat") == 0)
 326                                 packettype = PT_VAT;
 327                         else if (strcasecmp(optarg, "wb") == 0)
 328                                 packettype = PT_WB;
 329                         else if (strcasecmp(optarg, "rpc") == 0)
 330                                 packettype = PT_RPC;
 331                         else if (strcasecmp(optarg, "rtp") == 0)
 332                                 packettype = PT_RTP;
 333                         else if (strcasecmp(optarg, "rtcp") == 0)
 334                                 packettype = PT_RTCP;
 335                         else if (strcasecmp(optarg, "snmp") == 0)
 336                                 packettype = PT_SNMP;
 337                         else if (strcasecmp(optarg, "cnfp") == 0)
 338                                 packettype = PT_CNFP;
 339                         else
 340                                 error("unknown packet type `%s'", optarg);
 341                         break;
 342
 343                 case 'u':
 344                         ++uflag;
 345                         break;
 346
 347                 case 'v':
 348                         ++vflag;
 349                         break;
 350
 351                 case 'w':
 352                         WFileName = optarg;
 353                         break;
 354
 355                 case 'x':
 356                         ++xflag;
 357                         break;
 358
 359                 case 'X':
 360                         ++xflag;
 361                         ++Xflag;
 362                         break;
 363
 364 #ifdef YYDEBUG
 365                 case 'Y':
 366                         {
 367                         /* Undocumented flag */
 368                         extern int yydebug;
 369                         yydebug = 1;
 370                         }
 371                         break;
 372 #endif
 373                 default:
 374                         usage();
 375                         /* NOTREACHED */
 376                 }
 377
 378         if (aflag && nflag)
 379                 error("-a and -n options are incompatible");
 380
 381         if (tflag > 0)
 382                 thiszone = gmt2local(0);
 383
 384         if (RFileName != NULL) {
 385                 /*
 386                  * We don't need network access, so set it back to the user id.
 387                  * Also, this prevents the user from reading anyone's
 388                  * trace file.
 389                  */
 390                 setuid(getuid());
 391
 392                 pd = pcap_open_offline(RFileName, ebuf);
 393                 if (pd == NULL)
 394                         error("%s", ebuf);
 395                 localnet = 0;
 396                 netmask = 0;
 397                 if (fflag != 0)
 398                         error("-f and -r options are incompatible");
 399         } else {
 400                 if (device == NULL) {
 401                         device = pcap_lookupdev(ebuf);
 402                         if (device == NULL)
 403                                 error("%s", ebuf);
 404                 }
 405                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 406                 if (pd == NULL)
 407                         error("%s", ebuf);
 408                 i = pcap_snapshot(pd);
 409                 if (snaplen < i) {
 410                         warning("snaplen raised from %d to %d", snaplen, i);
 411                         snaplen = i;
 412                 }
 413                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 414                         localnet = 0;
 415                         netmask = 0;
 416                         warning("%s", ebuf);
 417                 }
 418                 /*
 419                  * Let user own process after socket has been opened.
 420                  */
 421                 setuid(getuid());
 422         }
 423         if (infile)
 424                 cmdbuf = read_infile(infile);
 425         else
 426                 cmdbuf = copy_argv(&argv[optind]);
 427
 428         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 429                 error("%s", pcap_geterr(pd));
 430         if (dflag) {
 431                 bpf_dump(&fcode, dflag);
 432                 exit(0);
 433         }
 434         init_addrtoname(localnet, netmask);
 435
 436         (void)setsignal(SIGTERM, cleanup);
 437         (void)setsignal(SIGINT, cleanup);
 438         /* Cooperate with nohup(1) */
 439         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 440                 (void)setsignal(SIGHUP, oldhandler);
 441
 442         if (pcap_setfilter(pd, &fcode) < 0)
 443                 error("%s", pcap_geterr(pd));
 444         if (WFileName) {
 445                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 446                 if (p == NULL)
 447                         error("%s", pcap_geterr(pd));
 448                 printer = pcap_dump;
 449                 pcap_userdata = (u_char *)p;
 450         } else {
 451                 printer = lookup_printer(pcap_datalink(pd));
 452                 pcap_userdata = 0;
 453         }
 454         if (RFileName == NULL) {
 455                 (void)fprintf(stderr, "%s: listening on %s\n",
 456                     program_name, device);
 457                 (void)fflush(stderr);
 458         }
 459         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 460                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 461                     program_name, pcap_geterr(pd));
 462                 exit(1);
 463         }
 464         pcap_close(pd);
 465         exit(0);
 466 }
 467
 468 /* make a clean exit on interrupts */
 469 static RETSIGTYPE
 470 cleanup(int signo)
 471 {
 472         struct pcap_stat stat;
 473
 474         /* Can't print the summary if reading from a savefile */
 475         if (pd != NULL && pcap_file(pd) == NULL) {
 476                 (void)fflush(stdout);
 477                 putc('\n', stderr);
 478                 if (pcap_stats(pd, &stat) < 0)
 479                         (void)fprintf(stderr, "pcap_stats: %s\n",
 480                             pcap_geterr(pd));
 481                 else {
 482                         (void)fprintf(stderr, "%d packets received by filter\n",
 483                             stat.ps_recv);
 484                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 485                             stat.ps_drop);
 486                 }
 487         }
 488         exit(0);
 489 }
 490
 491 /* Like default_print() but data need not be aligned */
 492 void
 493 default_print_unaligned(register const u_char *cp, register u_int length)
 494 {
 495         register u_int i, s;
 496         register int nshorts;
 497
 498         if (Xflag) {
 499                 ascii_print(cp, length);
 500                 return;
 501         }
 502         nshorts = (u_int) length / sizeof(u_short);
 503         i = 0;
 504         while (--nshorts >= 0) {
 505                 if ((i++ % 8) == 0)
 506                         (void)printf("\n\t\t\t");
 507                 s = *cp++;
 508                 (void)printf(" %02x%02x", s, *cp++);
 509         }
 510         if (length & 1) {
 511                 if ((i % 8) == 0)
 512                         (void)printf("\n\t\t\t");
 513                 (void)printf(" %02x", *cp);
 514         }
 515 }
 516
 517 /*
 518  * By default, print the packet out in hex.
 519  */
 520 void
 521 default_print(register const u_char *bp, register u_int length)
 522 {
 523         default_print_unaligned(bp, length);
 524 }
 525
 526 static void
 527 usage(void)
 528 {
 529         extern char version[];
 530         extern char pcap_version[];
 531
 532         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 533         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 534         (void)fprintf(stderr,
 535 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 536         (void)fprintf(stderr,
 537 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 538         (void)fprintf(stderr,
 539 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 540         exit(-1);
 541 }