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 1.149 2000-07-11 00:49:17 assar 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 static struct printer printers[] = {
 104         { ether_if_print,       DLT_EN10MB },
 105         { ether_if_print,       DLT_IEEE802 },
 106 #ifdef DLT_LANE8023
 107         { lane_if_print,        DLT_LANE8023 },
 108 #endif
 109 #ifdef DLT_CIP
 110         { cip_if_print,         DLT_CIP },
 111 #endif
 112         { sl_if_print,          DLT_SLIP },
 113         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 114         { ppp_if_print,         DLT_PPP },
 115         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 116         { fddi_if_print,        DLT_FDDI },
 117         { null_if_print,        DLT_NULL },
 118         { raw_if_print,         DLT_RAW },
 119         { atm_if_print,         DLT_ATM_RFC1483 },
 120 #ifdef DLT_CHDLC
 121         { chdlc_if_print,       DLT_CHDLC },
 122 #endif
 123         { NULL,                 0 },
 124 };
 125
 126 static pcap_handler
 127 lookup_printer(int type)
 128 {
 129         struct printer *p;
 130
 131         for (p = printers; p->f; ++p)
 132                 if (type == p->type)
 133                         return p->f;
 134
 135         error("unknown data link type 0x%x", type);
 136         /* NOTREACHED */
 137 }
 138
 139 static pcap_t *pd;
 140
 141 extern int optind;
 142 extern int opterr;
 143 extern char *optarg;
 144
 145 int
 146 main(int argc, char **argv)
 147 {
 148         register int cnt, op, i;
 149         bpf_u_int32 localnet, netmask;
 150         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 151         pcap_handler printer;
 152         struct bpf_program fcode;
 153         RETSIGTYPE (*oldhandler)(int);
 154         u_char *pcap_userdata;
 155         char ebuf[PCAP_ERRBUF_SIZE];
 156
 157         cnt = -1;
 158         device = NULL;
 159         infile = NULL;
 160         RFileName = NULL;
 161         WFileName = NULL;
 162         if ((cp = strrchr(argv[0], '/')) != NULL)
 163                 program_name = cp + 1;
 164         else
 165                 program_name = argv[0];
 166
 167         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 168                 error("%s", ebuf);
 169
 170 #ifdef LIBSMI
 171         smiInit("tcpdump");
 172 #endif
 173
 174         opterr = 0;
 175         while (
 176             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 177                 switch (op) {
 178
 179                 case 'a':
 180                         ++aflag;
 181                         break;
 182
 183                 case 'c':
 184                         cnt = atoi(optarg);
 185                         if (cnt <= 0)
 186                                 error("invalid packet count %s", optarg);
 187                         break;
 188
 189                 case 'd':
 190                         ++dflag;
 191                         break;
 192
 193                 case 'e':
 194                         ++eflag;
 195                         break;
 196
 197                 case 'E':
 198 #ifndef HAVE_LIBCRYPTO
 199                         warning("crypto code not compiled in");
 200 #endif
 201                         espsecret = optarg;
 202                         break;
 203
 204                 case 'f':
 205                         ++fflag;
 206                         break;
 207
 208                 case 'F':
 209                         infile = optarg;
 210                         break;
 211
 212                 case 'i':
 213                         device = optarg;
 214                         break;
 215
 216                 case 'l':
 217 #ifdef HAVE_SETLINEBUF
 218                         setlinebuf(stdout);
 219 #else
 220                         setvbuf(stdout, NULL, _IOLBF, 0);
 221 #endif
 222                         break;
 223
 224                 case 'n':
 225                         ++nflag;
 226                         break;
 227
 228                 case 'N':
 229                         ++Nflag;
 230                         break;
 231
 232                 case 'm':
 233 #ifdef LIBSMI
 234                         if (smiLoadModule(optarg) == 0) {
 235                                 error("could not load MIB module %s", optarg);
 236                         }
 237                         sflag = 1;
 238 #else
 239                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 240                                       program_name, optarg);
 241                         (void)fprintf(stderr, "(no libsmi support)\n");
 242 #endif
 243
 244                 case 'O':
 245                         Oflag = 0;
 246                         break;
 247
 248                 case 'p':
 249                         ++pflag;
 250                         break;
 251
 252                 case 'q':
 253                         ++qflag;
 254                         break;
 255
 256                 case 'r':
 257                         RFileName = optarg;
 258                         break;
 259
 260                 case 'R':
 261                         Rflag = 0;
 262                         break;
 263
 264                 case 's': {
 265                         char *end;
 266
 267                         snaplen = strtol(optarg, &end, 0);
 268                         if (optarg == end || *end != '\0'
 269                             || snaplen < 0 || snaplen > 65535)
 270                                 error("invalid snaplen %s", optarg);
 271                         else if (snaplen == 0)
 272                                 snaplen = 65535;
 273                         break;
 274                 }
 275
 276                 case 'S':
 277                         ++Sflag;
 278                         break;
 279
 280                 case 't':
 281                         --tflag;
 282                         break;
 283
 284                 case 'T':
 285                         if (strcasecmp(optarg, "vat") == 0)
 286                                 packettype = PT_VAT;
 287                         else if (strcasecmp(optarg, "wb") == 0)
 288                                 packettype = PT_WB;
 289                         else if (strcasecmp(optarg, "rpc") == 0)
 290                                 packettype = PT_RPC;
 291                         else if (strcasecmp(optarg, "rtp") == 0)
 292                                 packettype = PT_RTP;
 293                         else if (strcasecmp(optarg, "rtcp") == 0)
 294                                 packettype = PT_RTCP;
 295                         else if (strcasecmp(optarg, "snmp") == 0)
 296                                 packettype = PT_SNMP;
 297                         else if (strcasecmp(optarg, "cnfp") == 0)
 298                                 packettype = PT_CNFP;
 299                         else
 300                                 error("unknown packet type `%s'", optarg);
 301                         break;
 302
 303                 case 'u':
 304                         ++uflag;
 305                         break;
 306
 307                 case 'v':
 308                         ++vflag;
 309                         break;
 310
 311                 case 'w':
 312                         WFileName = optarg;
 313                         break;
 314
 315                 case 'x':
 316                         ++xflag;
 317                         break;
 318
 319                 case 'X':
 320                         ++xflag;
 321                         ++Xflag;
 322                         break;
 323
 324 #ifdef YYDEBUG
 325                 case 'Y':
 326                         {
 327                         /* Undocumented flag */
 328                         extern int yydebug;
 329                         yydebug = 1;
 330                         }
 331                         break;
 332 #endif
 333                 default:
 334                         usage();
 335                         /* NOTREACHED */
 336                 }
 337
 338         if (aflag && nflag)
 339                 error("-a and -n options are incompatible");
 340
 341         if (tflag > 0)
 342                 thiszone = gmt2local(0);
 343
 344         if (RFileName != NULL) {
 345                 /*
 346                  * We don't need network access, so set it back to the user id.
 347                  * Also, this prevents the user from reading anyone's
 348                  * trace file.
 349                  */
 350                 setuid(getuid());
 351
 352                 pd = pcap_open_offline(RFileName, ebuf);
 353                 if (pd == NULL)
 354                         error("%s", ebuf);
 355                 localnet = 0;
 356                 netmask = 0;
 357                 if (fflag != 0)
 358                         error("-f and -r options are incompatible");
 359         } else {
 360                 if (device == NULL) {
 361                         device = pcap_lookupdev(ebuf);
 362                         if (device == NULL)
 363                                 error("%s", ebuf);
 364                 }
 365                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 366                 if (pd == NULL)
 367                         error("%s", ebuf);
 368                 i = pcap_snapshot(pd);
 369                 if (snaplen < i) {
 370                         warning("snaplen raised from %d to %d", snaplen, i);
 371                         snaplen = i;
 372                 }
 373                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 374                         localnet = 0;
 375                         netmask = 0;
 376                         warning("%s", ebuf);
 377                 }
 378                 /*
 379                  * Let user own process after socket has been opened.
 380                  */
 381                 setuid(getuid());
 382         }
 383         if (infile)
 384                 cmdbuf = read_infile(infile);
 385         else
 386                 cmdbuf = copy_argv(&argv[optind]);
 387
 388         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 389                 error("%s", pcap_geterr(pd));
 390         if (dflag) {
 391                 bpf_dump(&fcode, dflag);
 392                 exit(0);
 393         }
 394         init_addrtoname(localnet, netmask);
 395
 396         (void)setsignal(SIGTERM, cleanup);
 397         (void)setsignal(SIGINT, cleanup);
 398         /* Cooperate with nohup(1) */
 399         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 400                 (void)setsignal(SIGHUP, oldhandler);
 401
 402         if (pcap_setfilter(pd, &fcode) < 0)
 403                 error("%s", pcap_geterr(pd));
 404         if (WFileName) {
 405                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 406                 if (p == NULL)
 407                         error("%s", pcap_geterr(pd));
 408                 printer = pcap_dump;
 409                 pcap_userdata = (u_char *)p;
 410         } else {
 411                 printer = lookup_printer(pcap_datalink(pd));
 412                 pcap_userdata = 0;
 413         }
 414         if (RFileName == NULL) {
 415                 (void)fprintf(stderr, "%s: listening on %s\n",
 416                     program_name, device);
 417                 (void)fflush(stderr);
 418         }
 419         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 420                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 421                     program_name, pcap_geterr(pd));
 422                 exit(1);
 423         }
 424         pcap_close(pd);
 425         exit(0);
 426 }
 427
 428 /* make a clean exit on interrupts */
 429 static RETSIGTYPE
 430 cleanup(int signo)
 431 {
 432         struct pcap_stat stat;
 433
 434         /* Can't print the summary if reading from a savefile */
 435         if (pd != NULL && pcap_file(pd) == NULL) {
 436                 (void)fflush(stdout);
 437                 putc('\n', stderr);
 438                 if (pcap_stats(pd, &stat) < 0)
 439                         (void)fprintf(stderr, "pcap_stats: %s\n",
 440                             pcap_geterr(pd));
 441                 else {
 442                         (void)fprintf(stderr, "%d packets received by filter\n",
 443                             stat.ps_recv);
 444                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 445                             stat.ps_drop);
 446                 }
 447         }
 448         exit(0);
 449 }
 450
 451 /* Like default_print() but data need not be aligned */
 452 void
 453 default_print_unaligned(register const u_char *cp, register u_int length)
 454 {
 455         register u_int i, s;
 456         register int nshorts;
 457
 458         if (Xflag) {
 459                 ascii_print(cp, length);
 460                 return;
 461         }
 462         nshorts = (u_int) length / sizeof(u_short);
 463         i = 0;
 464         while (--nshorts >= 0) {
 465                 if ((i++ % 8) == 0)
 466                         (void)printf("\n\t\t\t");
 467                 s = *cp++;
 468                 (void)printf(" %02x%02x", s, *cp++);
 469         }
 470         if (length & 1) {
 471                 if ((i % 8) == 0)
 472                         (void)printf("\n\t\t\t");
 473                 (void)printf(" %02x", *cp);
 474         }
 475 }
 476
 477 /*
 478  * By default, print the packet out in hex.
 479  */
 480 void
 481 default_print(register const u_char *bp, register u_int length)
 482 {
 483         default_print_unaligned(bp, length);
 484 }
 485
 486 static void
 487 usage(void)
 488 {
 489         extern char version[];
 490         extern char pcap_version[];
 491
 492         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 493         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 494         (void)fprintf(stderr,
 495 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 496         (void)fprintf(stderr,
 497 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 498         (void)fprintf(stderr,
 499 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 500         exit(-1);
 501 }