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 1.154 2000-09-29 04:58:53 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 /*
 102  * This table checks some DLT_* codes as well as checking PCAP_ENCAP_*
 103  * codes, so that those DLT_* codes that aren't the same on all platforms
 104  * (and thus don't have values identical to the values of the corresponding
 105  * PCAP_ENCAP_* codes) are, at least, handled on the platform that wrote
 106  * the capture file.
 107  *
 108  * (This may result in two identical entries in the table, if there's
 109  * a DLT_* code defined to have the same value as the corresponding
 110  * PCAP_ENCAP_* code.  Those duplicate entries are harmless.)
 111  */
 112 static struct printer printers[] = {
 113         /*
 114          * PCAP_ENCAP_* codes that correspond to DLT_* codes whose values
 115          * are the same on all platforms (the PCAP_ENCAP_* code values
 116          * are the same as the DLT_* code values).
 117          */
 118         { null_if_print,        PCAP_ENCAP_NULL },
 119         { ether_if_print,       PCAP_ENCAP_ETHERNET },
 120         { token_if_print,       PCAP_ENCAP_TOKEN_RING },
 121         { sl_if_print,          PCAP_ENCAP_SLIP },
 122         { ppp_if_print,         PCAP_ENCAP_PPP },
 123         { fddi_if_print,        PCAP_ENCAP_FDDI },
 124
 125         /*
 126          * DLT_* codes that aren't the same on all platforms, or that
 127          * aren't present on all platforms.
 128          */
 129 #ifdef DLT_ATM_RFC1483
 130         { atm_if_print,         DLT_ATM_RFC1483 },
 131 #endif
 132 #ifdef DLT_RAW
 133         { raw_if_print,         DLT_RAW },
 134 #endif
 135 #ifdef DLT_SLIP_BSDOS
 136         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 137 #endif
 138 #ifdef DLT_PPP_BSDOS
 139         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 140 #endif
 141 #ifdef DLT_CIP
 142         { cip_if_print,         DLT_CIP },
 143 #endif
 144 #ifdef DLT_ATM_CLIP
 145         { cip_if_print,         DLT_ATM_CLIP },
 146 #endif
 147 #ifdef DLT_LANE8023
 148         { lane_if_print,        DLT_LANE8023 },
 149 #endif
 150 #ifdef DLT_PPP_SERIAL
 151         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 152 #endif
 153
 154         /*
 155          * PCAP_ENCAP_* codes corresponding to DLT_* codes that aren't
 156          * necessarily the same on all platforms, and PCAP_ENCAP_* codes
 157          * for which there aren't DLT_* codes.
 158          */
 159         { atm_if_print,         PCAP_ENCAP_ATM_RFC1483 },
 160         { raw_if_print,         PCAP_ENCAP_RAW },
 161         { sl_bsdos_if_print,    PCAP_ENCAP_SLIP_BSDOS },
 162         { ppp_bsdos_if_print,   PCAP_ENCAP_PPP_BSDOS },
 163         { chdlc_if_print,       PCAP_ENCAP_C_HDLC },
 164         { cip_if_print,         PCAP_ENCAP_ATM_CLIP },
 165         { ppp_hdlc_if_print,    PCAP_ENCAP_PPP_HDLC },
 166         { NULL,                 0 },
 167 };
 168
 169 static pcap_handler
 170 lookup_printer(int type)
 171 {
 172         struct printer *p;
 173
 174         for (p = printers; p->f; ++p)
 175                 if (type == p->type)
 176                         return p->f;
 177
 178         error("unknown data link type %d", type);
 179         /* NOTREACHED */
 180 }
 181
 182 static pcap_t *pd;
 183
 184 extern int optind;
 185 extern int opterr;
 186 extern char *optarg;
 187
 188 int
 189 main(int argc, char **argv)
 190 {
 191         register int cnt, op, i;
 192         bpf_u_int32 localnet, netmask;
 193         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 194         pcap_handler printer;
 195         struct bpf_program fcode;
 196         RETSIGTYPE (*oldhandler)(int);
 197         u_char *pcap_userdata;
 198         char ebuf[PCAP_ERRBUF_SIZE];
 199
 200         cnt = -1;
 201         device = NULL;
 202         infile = NULL;
 203         RFileName = NULL;
 204         WFileName = NULL;
 205         if ((cp = strrchr(argv[0], '/')) != NULL)
 206                 program_name = cp + 1;
 207         else
 208                 program_name = argv[0];
 209
 210         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 211                 error("%s", ebuf);
 212
 213 #ifdef LIBSMI
 214         smiInit("tcpdump");
 215 #endif
 216
 217         opterr = 0;
 218         while (
 219             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 220                 switch (op) {
 221
 222                 case 'a':
 223                         ++aflag;
 224                         break;
 225
 226                 case 'c':
 227                         cnt = atoi(optarg);
 228                         if (cnt <= 0)
 229                                 error("invalid packet count %s", optarg);
 230                         break;
 231
 232                 case 'd':
 233                         ++dflag;
 234                         break;
 235
 236                 case 'e':
 237                         ++eflag;
 238                         break;
 239
 240                 case 'E':
 241 #ifndef HAVE_LIBCRYPTO
 242                         warning("crypto code not compiled in");
 243 #endif
 244                         espsecret = optarg;
 245                         break;
 246
 247                 case 'f':
 248                         ++fflag;
 249                         break;
 250
 251                 case 'F':
 252                         infile = optarg;
 253                         break;
 254
 255                 case 'i':
 256                         device = optarg;
 257                         break;
 258
 259                 case 'l':
 260 #ifdef HAVE_SETLINEBUF
 261                         setlinebuf(stdout);
 262 #else
 263                         setvbuf(stdout, NULL, _IOLBF, 0);
 264 #endif
 265                         break;
 266
 267                 case 'n':
 268                         ++nflag;
 269                         break;
 270
 271                 case 'N':
 272                         ++Nflag;
 273                         break;
 274
 275                 case 'm':
 276 #ifdef LIBSMI
 277                         if (smiLoadModule(optarg) == 0) {
 278                                 error("could not load MIB module %s", optarg);
 279                         }
 280                         sflag = 1;
 281 #else
 282                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 283                                       program_name, optarg);
 284                         (void)fprintf(stderr, "(no libsmi support)\n");
 285 #endif
 286
 287                 case 'O':
 288                         Oflag = 0;
 289                         break;
 290
 291                 case 'p':
 292                         ++pflag;
 293                         break;
 294
 295                 case 'q':
 296                         ++qflag;
 297                         break;
 298
 299                 case 'r':
 300                         RFileName = optarg;
 301                         break;
 302
 303                 case 'R':
 304                         Rflag = 0;
 305                         break;
 306
 307                 case 's': {
 308                         char *end;
 309
 310                         snaplen = strtol(optarg, &end, 0);
 311                         if (optarg == end || *end != '\0'
 312                             || snaplen < 0 || snaplen > 65535)
 313                                 error("invalid snaplen %s", optarg);
 314                         else if (snaplen == 0)
 315                                 snaplen = 65535;
 316                         break;
 317                 }
 318
 319                 case 'S':
 320                         ++Sflag;
 321                         break;
 322
 323                 case 't':
 324                         --tflag;
 325                         break;
 326
 327                 case 'T':
 328                         if (strcasecmp(optarg, "vat") == 0)
 329                                 packettype = PT_VAT;
 330                         else if (strcasecmp(optarg, "wb") == 0)
 331                                 packettype = PT_WB;
 332                         else if (strcasecmp(optarg, "rpc") == 0)
 333                                 packettype = PT_RPC;
 334                         else if (strcasecmp(optarg, "rtp") == 0)
 335                                 packettype = PT_RTP;
 336                         else if (strcasecmp(optarg, "rtcp") == 0)
 337                                 packettype = PT_RTCP;
 338                         else if (strcasecmp(optarg, "snmp") == 0)
 339                                 packettype = PT_SNMP;
 340                         else if (strcasecmp(optarg, "cnfp") == 0)
 341                                 packettype = PT_CNFP;
 342                         else
 343                                 error("unknown packet type `%s'", optarg);
 344                         break;
 345
 346                 case 'u':
 347                         ++uflag;
 348                         break;
 349
 350                 case 'v':
 351                         ++vflag;
 352                         break;
 353
 354                 case 'w':
 355                         WFileName = optarg;
 356                         break;
 357
 358                 case 'x':
 359                         ++xflag;
 360                         break;
 361
 362                 case 'X':
 363                         ++xflag;
 364                         ++Xflag;
 365                         break;
 366
 367 #ifdef YYDEBUG
 368                 case 'Y':
 369                         {
 370                         /* Undocumented flag */
 371                         extern int yydebug;
 372                         yydebug = 1;
 373                         }
 374                         break;
 375 #endif
 376                 default:
 377                         usage();
 378                         /* NOTREACHED */
 379                 }
 380
 381         if (aflag && nflag)
 382                 error("-a and -n options are incompatible");
 383
 384         if (tflag > 0)
 385                 thiszone = gmt2local(0);
 386
 387         if (RFileName != NULL) {
 388                 /*
 389                  * We don't need network access, so set it back to the user id.
 390                  * Also, this prevents the user from reading anyone's
 391                  * trace file.
 392                  */
 393                 setuid(getuid());
 394
 395                 pd = pcap_open_offline(RFileName, ebuf);
 396                 if (pd == NULL)
 397                         error("%s", ebuf);
 398                 localnet = 0;
 399                 netmask = 0;
 400                 if (fflag != 0)
 401                         error("-f and -r options are incompatible");
 402         } else {
 403                 if (device == NULL) {
 404                         device = pcap_lookupdev(ebuf);
 405                         if (device == NULL)
 406                                 error("%s", ebuf);
 407                 }
 408                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 409                 if (pd == NULL)
 410                         error("%s", ebuf);
 411                 i = pcap_snapshot(pd);
 412                 if (snaplen < i) {
 413                         warning("snaplen raised from %d to %d", snaplen, i);
 414                         snaplen = i;
 415                 }
 416                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 417                         localnet = 0;
 418                         netmask = 0;
 419                         warning("%s", ebuf);
 420                 }
 421                 /*
 422                  * Let user own process after socket has been opened.
 423                  */
 424                 setuid(getuid());
 425         }
 426         if (infile)
 427                 cmdbuf = read_infile(infile);
 428         else
 429                 cmdbuf = copy_argv(&argv[optind]);
 430
 431         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 432                 error("%s", pcap_geterr(pd));
 433         if (dflag) {
 434                 bpf_dump(&fcode, dflag);
 435                 exit(0);
 436         }
 437         init_addrtoname(localnet, netmask);
 438
 439         (void)setsignal(SIGTERM, cleanup);
 440         (void)setsignal(SIGINT, cleanup);
 441         /* Cooperate with nohup(1) */
 442         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 443                 (void)setsignal(SIGHUP, oldhandler);
 444
 445         if (pcap_setfilter(pd, &fcode) < 0)
 446                 error("%s", pcap_geterr(pd));
 447         if (WFileName) {
 448                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 449                 if (p == NULL)
 450                         error("%s", pcap_geterr(pd));
 451                 printer = pcap_dump;
 452                 pcap_userdata = (u_char *)p;
 453         } else {
 454                 printer = lookup_printer(pcap_datalink(pd));
 455                 pcap_userdata = 0;
 456         }
 457         if (RFileName == NULL) {
 458                 (void)fprintf(stderr, "%s: listening on %s\n",
 459                     program_name, device);
 460                 (void)fflush(stderr);
 461         }
 462         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 463                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 464                     program_name, pcap_geterr(pd));
 465                 exit(1);
 466         }
 467         pcap_close(pd);
 468         exit(0);
 469 }
 470
 471 /* make a clean exit on interrupts */
 472 static RETSIGTYPE
 473 cleanup(int signo)
 474 {
 475         struct pcap_stat stat;
 476
 477         /* Can't print the summary if reading from a savefile */
 478         if (pd != NULL && pcap_file(pd) == NULL) {
 479                 (void)fflush(stdout);
 480                 putc('\n', stderr);
 481                 if (pcap_stats(pd, &stat) < 0)
 482                         (void)fprintf(stderr, "pcap_stats: %s\n",
 483                             pcap_geterr(pd));
 484                 else {
 485                         (void)fprintf(stderr, "%d packets received by filter\n",
 486                             stat.ps_recv);
 487                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 488                             stat.ps_drop);
 489                 }
 490         }
 491         exit(0);
 492 }
 493
 494 /* Like default_print() but data need not be aligned */
 495 void
 496 default_print_unaligned(register const u_char *cp, register u_int length)
 497 {
 498         register u_int i, s;
 499         register int nshorts;
 500
 501         if (Xflag) {
 502                 ascii_print(cp, length);
 503                 return;
 504         }
 505         nshorts = (u_int) length / sizeof(u_short);
 506         i = 0;
 507         while (--nshorts >= 0) {
 508                 if ((i++ % 8) == 0)
 509                         (void)printf("\n\t\t\t");
 510                 s = *cp++;
 511                 (void)printf(" %02x%02x", s, *cp++);
 512         }
 513         if (length & 1) {
 514                 if ((i % 8) == 0)
 515                         (void)printf("\n\t\t\t");
 516                 (void)printf(" %02x", *cp);
 517         }
 518 }
 519
 520 /*
 521  * By default, print the packet out in hex.
 522  */
 523 void
 524 default_print(register const u_char *bp, register u_int length)
 525 {
 526         default_print_unaligned(bp, length);
 527 }
 528
 529 static void
 530 usage(void)
 531 {
 532         extern char version[];
 533         extern char pcap_version[];
 534
 535         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 536         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 537         (void)fprintf(stderr,
 538 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 539         (void)fprintf(stderr,
 540 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 541         (void)fprintf(stderr,
 542 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 543         exit(-1);
 544 }