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 1.142 2000-01-17 06:24:27 itojun 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 vflag;                      /* verbose */
  78 int xflag;                      /* print packet in hex */
  79 int Xflag;                      /* print packet in ascii as well as hex */
  80
  81 char *espsecret = NULL;         /* ESP secret key */
  82
  83 int packettype;
  84
  85
  86 char *program_name;
  87
  88 int32_t thiszone;               /* seconds offset from gmt to local time */
  89
  90 /* Externs */
  91 extern void bpf_dump(struct bpf_program *, int);
  92
  93 /* Forwards */
  94 RETSIGTYPE cleanup(int);
  95 extern __dead void usage(void) __attribute__((volatile));
  96
  97 /* Length of saved portion of packet. */
  98 int snaplen = DEFAULT_SNAPLEN;
  99
 100 struct printer {
 101         pcap_handler f;
 102         int type;
 103 };
 104
 105 static struct printer printers[] = {
 106         { ether_if_print,       DLT_EN10MB },
 107         { ether_if_print,       DLT_IEEE802 },
 108 #ifdef DLT_LANE8023
 109         { lane_if_print,        DLT_LANE8023 },
 110 #endif
 111 #ifdef DLT_CIP
 112         { cip_if_print,         DLT_CIP },
 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         { raw_if_print,         DLT_RAW },
 121         { atm_if_print,         DLT_ATM_RFC1483 },
 122 #ifdef DLT_CHDLC
 123         { chdlc_if_print,       DLT_CHDLC },
 124 #endif
 125         { NULL,                 0 },
 126 };
 127
 128 static pcap_handler
 129 lookup_printer(int type)
 130 {
 131         struct printer *p;
 132
 133         for (p = printers; p->f; ++p)
 134                 if (type == p->type)
 135                         return p->f;
 136
 137         error("unknown data link type 0x%x", type);
 138         /* NOTREACHED */
 139 }
 140
 141 static pcap_t *pd;
 142
 143 extern int optind;
 144 extern int opterr;
 145 extern char *optarg;
 146
 147 int
 148 main(int argc, char **argv)
 149 {
 150         register int cnt, op, i;
 151         bpf_u_int32 localnet, netmask;
 152         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 153         pcap_handler printer;
 154         struct bpf_program fcode;
 155         RETSIGTYPE (*oldhandler)(int);
 156         u_char *pcap_userdata;
 157         char ebuf[PCAP_ERRBUF_SIZE];
 158
 159         cnt = -1;
 160         device = NULL;
 161         infile = NULL;
 162         RFileName = NULL;
 163         WFileName = NULL;
 164         if ((cp = strrchr(argv[0], '/')) != NULL)
 165                 program_name = cp + 1;
 166         else
 167                 program_name = argv[0];
 168
 169         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 170                 error("%s", ebuf);
 171
 172 #ifdef LIBSMI
 173         smiInit("tcpdump");
 174 #endif
 175
 176         opterr = 0;
 177         while (
 178             (op = getopt(argc, argv, "ac:deE:fF:i:lnNm:Opqr:Rs:StT:vw:xXY")) != EOF)
 179                 switch (op) {
 180
 181                 case 'a':
 182                         ++aflag;
 183                         break;
 184
 185                 case 'c':
 186                         cnt = atoi(optarg);
 187                         if (cnt <= 0)
 188                                 error("invalid packet count %s", optarg);
 189                         break;
 190
 191                 case 'd':
 192                         ++dflag;
 193                         break;
 194
 195                 case 'e':
 196                         ++eflag;
 197                         break;
 198
 199                 case 'E':
 200 #ifndef HAVE_LIBCRYPTO
 201                         warning("crypto code not compiled in");
 202 #endif
 203                         espsecret = optarg;
 204                         break;
 205
 206                 case 'f':
 207                         ++fflag;
 208                         break;
 209
 210                 case 'F':
 211                         infile = optarg;
 212                         break;
 213
 214                 case 'i':
 215                         device = optarg;
 216                         break;
 217
 218                 case 'l':
 219 #ifdef HAVE_SETLINEBUF
 220                         setlinebuf(stdout);
 221 #else
 222                         setvbuf(stdout, NULL, _IOLBF, 0);
 223 #endif
 224                         break;
 225
 226                 case 'n':
 227                         ++nflag;
 228                         break;
 229
 230                 case 'N':
 231                         ++Nflag;
 232                         break;
 233
 234                 case 'm':
 235 #ifdef LIBSMI
 236                         if (smiLoadModule(optarg) == 0) {
 237                                 error("could not load MIB module %s", optarg);
 238                         }
 239                         sflag = 1;
 240 #else
 241                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 242                                       program_name, optarg);
 243                         (void)fprintf(stderr, "(no libsmi support)\n");
 244 #endif
 245
 246                 case 'O':
 247                         Oflag = 0;
 248                         break;
 249
 250                 case 'p':
 251                         ++pflag;
 252                         break;
 253
 254                 case 'q':
 255                         ++qflag;
 256                         break;
 257
 258                 case 'r':
 259                         RFileName = optarg;
 260                         break;
 261
 262                 case 'R':
 263                         Rflag = 0;
 264                         break;
 265
 266                 case 's':
 267                         snaplen = atoi(optarg);
 268                         if (snaplen <= 0)
 269                                 error("invalid snaplen %s", optarg);
 270                         break;
 271
 272                 case 'S':
 273                         ++Sflag;
 274                         break;
 275
 276                 case 't':
 277                         --tflag;
 278                         break;
 279
 280                 case 'T':
 281                         if (strcasecmp(optarg, "vat") == 0)
 282                                 packettype = PT_VAT;
 283                         else if (strcasecmp(optarg, "wb") == 0)
 284                                 packettype = PT_WB;
 285                         else if (strcasecmp(optarg, "rpc") == 0)
 286                                 packettype = PT_RPC;
 287                         else if (strcasecmp(optarg, "rtp") == 0)
 288                                 packettype = PT_RTP;
 289                         else if (strcasecmp(optarg, "rtcp") == 0)
 290                                 packettype = PT_RTCP;
 291                         else if (strcasecmp(optarg, "snmp") == 0)
 292                                 packettype = PT_SNMP;
 293                         else
 294                                 error("unknown packet type `%s'", optarg);
 295                         break;
 296
 297                 case 'v':
 298                         ++vflag;
 299                         break;
 300
 301                 case 'w':
 302                         WFileName = optarg;
 303                         break;
 304
 305                 case 'x':
 306                         ++xflag;
 307                         break;
 308
 309                 case 'X':
 310                         ++xflag;
 311                         ++Xflag;
 312                         break;
 313
 314 #ifdef YYDEBUG
 315                 case 'Y':
 316                         {
 317                         /* Undocumented flag */
 318                         extern int yydebug;
 319                         yydebug = 1;
 320                         }
 321                         break;
 322 #endif
 323                 default:
 324                         usage();
 325                         /* NOTREACHED */
 326                 }
 327
 328         if (aflag && nflag)
 329                 error("-a and -n options are incompatible");
 330
 331         if (tflag > 0)
 332                 thiszone = gmt2local(0);
 333
 334         if (RFileName != NULL) {
 335                 /*
 336                  * We don't need network access, so set it back to the user id.
 337                  * Also, this prevents the user from reading anyone's
 338                  * trace file.
 339                  */
 340                 setuid(getuid());
 341
 342                 pd = pcap_open_offline(RFileName, ebuf);
 343                 if (pd == NULL)
 344                         error("%s", ebuf);
 345                 localnet = 0;
 346                 netmask = 0;
 347                 if (fflag != 0)
 348                         error("-f and -r options are incompatible");
 349         } else {
 350                 if (device == NULL) {
 351                         device = pcap_lookupdev(ebuf);
 352                         if (device == NULL)
 353                                 error("%s", ebuf);
 354                 }
 355                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 356                 if (pd == NULL)
 357                         error("%s", ebuf);
 358                 i = pcap_snapshot(pd);
 359                 if (snaplen < i) {
 360                         warning("snaplen raised from %d to %d", snaplen, i);
 361                         snaplen = i;
 362                 }
 363                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 364                         localnet = 0;
 365                         netmask = 0;
 366                         warning("%s", ebuf);
 367                 }
 368                 /*
 369                  * Let user own process after socket has been opened.
 370                  */
 371                 setuid(getuid());
 372         }
 373         if (infile)
 374                 cmdbuf = read_infile(infile);
 375         else
 376                 cmdbuf = copy_argv(&argv[optind]);
 377
 378         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 379                 error("%s", pcap_geterr(pd));
 380         if (dflag) {
 381                 bpf_dump(&fcode, dflag);
 382                 exit(0);
 383         }
 384         init_addrtoname(localnet, netmask);
 385
 386         (void)setsignal(SIGTERM, cleanup);
 387         (void)setsignal(SIGINT, cleanup);
 388         /* Cooperate with nohup(1) */
 389         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 390                 (void)setsignal(SIGHUP, oldhandler);
 391
 392         if (pcap_setfilter(pd, &fcode) < 0)
 393                 error("%s", pcap_geterr(pd));
 394         if (WFileName) {
 395                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 396                 if (p == NULL)
 397                         error("%s", pcap_geterr(pd));
 398                 printer = pcap_dump;
 399                 pcap_userdata = (u_char *)p;
 400         } else {
 401                 printer = lookup_printer(pcap_datalink(pd));
 402                 pcap_userdata = 0;
 403         }
 404         if (RFileName == NULL) {
 405                 (void)fprintf(stderr, "%s: listening on %s\n",
 406                     program_name, device);
 407                 (void)fflush(stderr);
 408         }
 409         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 410                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 411                     program_name, pcap_geterr(pd));
 412                 exit(1);
 413         }
 414         pcap_close(pd);
 415         exit(0);
 416 }
 417
 418 /* make a clean exit on interrupts */
 419 RETSIGTYPE
 420 cleanup(int signo)
 421 {
 422         struct pcap_stat stat;
 423
 424         /* Can't print the summary if reading from a savefile */
 425         if (pd != NULL && pcap_file(pd) == NULL) {
 426                 (void)fflush(stdout);
 427                 putc('\n', stderr);
 428                 if (pcap_stats(pd, &stat) < 0)
 429                         (void)fprintf(stderr, "pcap_stats: %s\n",
 430                             pcap_geterr(pd));
 431                 else {
 432                         (void)fprintf(stderr, "%d packets received by filter\n",
 433                             stat.ps_recv);
 434                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 435                             stat.ps_drop);
 436                 }
 437         }
 438         exit(0);
 439 }
 440
 441 /* Like default_print() but data need not be aligned */
 442 void
 443 default_print_unaligned(register const u_char *cp, register u_int length)
 444 {
 445         register u_int i, s;
 446         register int nshorts;
 447
 448         if (Xflag) {
 449                 ascii_print(cp, length);
 450                 return;
 451         }
 452         nshorts = (u_int) length / sizeof(u_short);
 453         i = 0;
 454         while (--nshorts >= 0) {
 455                 if ((i++ % 8) == 0)
 456                         (void)printf("\n\t\t\t");
 457                 s = *cp++;
 458                 (void)printf(" %02x%02x", s, *cp++);
 459         }
 460         if (length & 1) {
 461                 if ((i % 8) == 0)
 462                         (void)printf("\n\t\t\t");
 463                 (void)printf(" %02x", *cp);
 464         }
 465 }
 466
 467 /*
 468  * By default, print the packet out in hex.
 469  */
 470 void
 471 default_print(register const u_char *bp, register u_int length)
 472 {
 473   default_print_unaligned(bp, length);
 474 }
 475
 476 __dead void
 477 usage(void)
 478 {
 479         extern char version[];
 480         extern char pcap_version[];
 481
 482         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 483         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 484         (void)fprintf(stderr,
 485 "Usage: %s [-adeflnNOpqStvxX] [-c count] [ -F file ]\n", program_name);
 486         (void)fprintf(stderr,
 487 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 488         (void)fprintf(stderr,
 489 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 490         exit(-1);
 491 }