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 1.156 2000-12-09 02:58:48 fenner 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         { ether_if_print,       DLT_EN10MB },
 103         { token_if_print,       DLT_IEEE802 },
 104 #ifdef DLT_LANE8023
 105         { lane_if_print,        DLT_LANE8023 },
 106 #endif
 107 #ifdef DLT_CIP
 108         { cip_if_print,         DLT_CIP },
 109 #endif
 110 #ifdef DLT_ATM_CLIP
 111         { cip_if_print,         DLT_ATM_CLIP },
 112 #endif
 113         { sl_if_print,          DLT_SLIP },
 114         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 115         { ppp_if_print,         DLT_PPP },
 116         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 117         { fddi_if_print,        DLT_FDDI },
 118         { null_if_print,        DLT_NULL },
 119         { raw_if_print,         DLT_RAW },
 120         { atm_if_print,         DLT_ATM_RFC1483 },
 121 #ifdef DLT_C_HDLC
 122         { chdlc_if_print,       DLT_C_HDLC },
 123 #endif
 124 #ifdef DLT_PPP_SERIAL
 125         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 126 #endif
 127         { NULL,                 0 },
 128 };
 129
 130 static pcap_handler
 131 lookup_printer(int type)
 132 {
 133         struct printer *p;
 134
 135         for (p = printers; p->f; ++p)
 136                 if (type == p->type)
 137                         return p->f;
 138
 139         error("unknown data link type %d", type);
 140         /* NOTREACHED */
 141 }
 142
 143 static pcap_t *pd;
 144
 145 extern int optind;
 146 extern int opterr;
 147 extern char *optarg;
 148
 149 int
 150 main(int argc, char **argv)
 151 {
 152         register int cnt, op, i;
 153         bpf_u_int32 localnet, netmask;
 154         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 155         pcap_handler printer;
 156         struct bpf_program fcode;
 157         RETSIGTYPE (*oldhandler)(int);
 158         u_char *pcap_userdata;
 159         char ebuf[PCAP_ERRBUF_SIZE];
 160
 161         cnt = -1;
 162         device = NULL;
 163         infile = NULL;
 164         RFileName = NULL;
 165         WFileName = NULL;
 166         if ((cp = strrchr(argv[0], '/')) != NULL)
 167                 program_name = cp + 1;
 168         else
 169                 program_name = argv[0];
 170
 171         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 172                 error("%s", ebuf);
 173
 174 #ifdef LIBSMI
 175         smiInit("tcpdump");
 176 #endif
 177
 178         opterr = 0;
 179         while (
 180             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 181                 switch (op) {
 182
 183                 case 'a':
 184                         ++aflag;
 185                         break;
 186
 187                 case 'c':
 188                         cnt = atoi(optarg);
 189                         if (cnt <= 0)
 190                                 error("invalid packet count %s", optarg);
 191                         break;
 192
 193                 case 'd':
 194                         ++dflag;
 195                         break;
 196
 197                 case 'e':
 198                         ++eflag;
 199                         break;
 200
 201                 case 'E':
 202 #ifndef HAVE_LIBCRYPTO
 203                         warning("crypto code not compiled in");
 204 #endif
 205                         espsecret = optarg;
 206                         break;
 207
 208                 case 'f':
 209                         ++fflag;
 210                         break;
 211
 212                 case 'F':
 213                         infile = optarg;
 214                         break;
 215
 216                 case 'i':
 217                         device = optarg;
 218                         break;
 219
 220                 case 'l':
 221 #ifdef HAVE_SETLINEBUF
 222                         setlinebuf(stdout);
 223 #else
 224                         setvbuf(stdout, NULL, _IOLBF, 0);
 225 #endif
 226                         break;
 227
 228                 case 'n':
 229                         ++nflag;
 230                         break;
 231
 232                 case 'N':
 233                         ++Nflag;
 234                         break;
 235
 236                 case 'm':
 237 #ifdef LIBSMI
 238                         if (smiLoadModule(optarg) == 0) {
 239                                 error("could not load MIB module %s", optarg);
 240                         }
 241                         sflag = 1;
 242 #else
 243                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 244                                       program_name, optarg);
 245                         (void)fprintf(stderr, "(no libsmi support)\n");
 246 #endif
 247
 248                 case 'O':
 249                         Oflag = 0;
 250                         break;
 251
 252                 case 'p':
 253                         ++pflag;
 254                         break;
 255
 256                 case 'q':
 257                         ++qflag;
 258                         break;
 259
 260                 case 'r':
 261                         RFileName = optarg;
 262                         break;
 263
 264                 case 'R':
 265                         Rflag = 0;
 266                         break;
 267
 268                 case 's': {
 269                         char *end;
 270
 271                         snaplen = strtol(optarg, &end, 0);
 272                         if (optarg == end || *end != '\0'
 273                             || snaplen < 0 || snaplen > 65535)
 274                                 error("invalid snaplen %s", optarg);
 275                         else if (snaplen == 0)
 276                                 snaplen = 65535;
 277                         break;
 278                 }
 279
 280                 case 'S':
 281                         ++Sflag;
 282                         break;
 283
 284                 case 't':
 285                         --tflag;
 286                         break;
 287
 288                 case 'T':
 289                         if (strcasecmp(optarg, "vat") == 0)
 290                                 packettype = PT_VAT;
 291                         else if (strcasecmp(optarg, "wb") == 0)
 292                                 packettype = PT_WB;
 293                         else if (strcasecmp(optarg, "rpc") == 0)
 294                                 packettype = PT_RPC;
 295                         else if (strcasecmp(optarg, "rtp") == 0)
 296                                 packettype = PT_RTP;
 297                         else if (strcasecmp(optarg, "rtcp") == 0)
 298                                 packettype = PT_RTCP;
 299                         else if (strcasecmp(optarg, "snmp") == 0)
 300                                 packettype = PT_SNMP;
 301                         else if (strcasecmp(optarg, "cnfp") == 0)
 302                                 packettype = PT_CNFP;
 303                         else
 304                                 error("unknown packet type `%s'", optarg);
 305                         break;
 306
 307                 case 'u':
 308                         ++uflag;
 309                         break;
 310
 311                 case 'v':
 312                         ++vflag;
 313                         break;
 314
 315                 case 'w':
 316                         WFileName = optarg;
 317                         break;
 318
 319                 case 'x':
 320                         ++xflag;
 321                         break;
 322
 323                 case 'X':
 324                         ++xflag;
 325                         ++Xflag;
 326                         break;
 327
 328 #ifdef YYDEBUG
 329                 case 'Y':
 330                         {
 331                         /* Undocumented flag */
 332                         extern int yydebug;
 333                         yydebug = 1;
 334                         }
 335                         break;
 336 #endif
 337                 default:
 338                         usage();
 339                         /* NOTREACHED */
 340                 }
 341
 342         if (aflag && nflag)
 343                 error("-a and -n options are incompatible");
 344
 345         if (tflag > 0)
 346                 thiszone = gmt2local(0);
 347
 348         if (RFileName != NULL) {
 349                 /*
 350                  * We don't need network access, so set it back to the user id.
 351                  * Also, this prevents the user from reading anyone's
 352                  * trace file.
 353                  */
 354                 setuid(getuid());
 355
 356                 pd = pcap_open_offline(RFileName, ebuf);
 357                 if (pd == NULL)
 358                         error("%s", ebuf);
 359                 localnet = 0;
 360                 netmask = 0;
 361                 if (fflag != 0)
 362                         error("-f and -r options are incompatible");
 363         } else {
 364                 if (device == NULL) {
 365                         device = pcap_lookupdev(ebuf);
 366                         if (device == NULL)
 367                                 error("%s", ebuf);
 368                 }
 369                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 370                 if (pd == NULL)
 371                         error("%s", ebuf);
 372                 i = pcap_snapshot(pd);
 373                 if (snaplen < i) {
 374                         warning("snaplen raised from %d to %d", snaplen, i);
 375                         snaplen = i;
 376                 }
 377                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 378                         localnet = 0;
 379                         netmask = 0;
 380                         warning("%s", ebuf);
 381                 }
 382                 /*
 383                  * Let user own process after socket has been opened.
 384                  */
 385                 setuid(getuid());
 386         }
 387         if (infile)
 388                 cmdbuf = read_infile(infile);
 389         else
 390                 cmdbuf = copy_argv(&argv[optind]);
 391
 392         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 393                 error("%s", pcap_geterr(pd));
 394         if (dflag) {
 395                 bpf_dump(&fcode, dflag);
 396                 exit(0);
 397         }
 398         init_addrtoname(localnet, netmask);
 399
 400         (void)setsignal(SIGTERM, cleanup);
 401         (void)setsignal(SIGINT, cleanup);
 402         /* Cooperate with nohup(1) */
 403         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 404                 (void)setsignal(SIGHUP, oldhandler);
 405
 406         if (pcap_setfilter(pd, &fcode) < 0)
 407                 error("%s", pcap_geterr(pd));
 408         if (WFileName) {
 409                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 410                 if (p == NULL)
 411                         error("%s", pcap_geterr(pd));
 412                 printer = pcap_dump;
 413                 pcap_userdata = (u_char *)p;
 414         } else {
 415                 printer = lookup_printer(pcap_datalink(pd));
 416                 pcap_userdata = 0;
 417         }
 418         if (RFileName == NULL) {
 419                 (void)fprintf(stderr, "%s: listening on %s\n",
 420                     program_name, device);
 421                 (void)fflush(stderr);
 422         }
 423         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 424                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 425                     program_name, pcap_geterr(pd));
 426                 exit(1);
 427         }
 428         pcap_close(pd);
 429         exit(0);
 430 }
 431
 432 /* make a clean exit on interrupts */
 433 static RETSIGTYPE
 434 cleanup(int signo)
 435 {
 436         struct pcap_stat stat;
 437
 438         /* Can't print the summary if reading from a savefile */
 439         if (pd != NULL && pcap_file(pd) == NULL) {
 440                 (void)fflush(stdout);
 441                 putc('\n', stderr);
 442                 if (pcap_stats(pd, &stat) < 0)
 443                         (void)fprintf(stderr, "pcap_stats: %s\n",
 444                             pcap_geterr(pd));
 445                 else {
 446                         (void)fprintf(stderr, "%d packets received by filter\n",
 447                             stat.ps_recv);
 448                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 449                             stat.ps_drop);
 450                 }
 451         }
 452         exit(0);
 453 }
 454
 455 /* Like default_print() but data need not be aligned */
 456 void
 457 default_print_unaligned(register const u_char *cp, register u_int length)
 458 {
 459         register u_int i, s;
 460         register int nshorts;
 461
 462         if (Xflag) {
 463                 ascii_print(cp, length);
 464                 return;
 465         }
 466         nshorts = (u_int) length / sizeof(u_short);
 467         i = 0;
 468         while (--nshorts >= 0) {
 469                 if ((i++ % 8) == 0)
 470                         (void)printf("\n\t\t\t");
 471                 s = *cp++;
 472                 (void)printf(" %02x%02x", s, *cp++);
 473         }
 474         if (length & 1) {
 475                 if ((i % 8) == 0)
 476                         (void)printf("\n\t\t\t");
 477                 (void)printf(" %02x", *cp);
 478         }
 479 }
 480
 481 /*
 482  * By default, print the packet out in hex.
 483  */
 484 void
 485 default_print(register const u_char *bp, register u_int length)
 486 {
 487         default_print_unaligned(bp, length);
 488 }
 489
 490 static void
 491 usage(void)
 492 {
 493         extern char version[];
 494         extern char pcap_version[];
 495
 496         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 497         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 498         (void)fprintf(stderr,
 499 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 500         (void)fprintf(stderr,
 501 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 502         (void)fprintf(stderr,
 503 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 504         exit(-1);
 505 }