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 1.160 2001-04-17 08:39:20 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 static struct printer printers[] = {
 102         { arcnet_if_print,      DLT_ARCNET },
 103         { ether_if_print,       DLT_EN10MB },
 104         { token_if_print,       DLT_IEEE802 },
 105 #ifdef DLT_LANE8023
 106         { lane_if_print,        DLT_LANE8023 },
 107 #endif
 108 #ifdef DLT_CIP
 109         { cip_if_print,         DLT_CIP },
 110 #endif
 111 #ifdef DLT_ATM_CLIP
 112         { cip_if_print,         DLT_ATM_CLIP },
 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 #ifdef DLT_LOOP
 121         { null_if_print,        DLT_LOOP },
 122 #endif
 123         { raw_if_print,         DLT_RAW },
 124         { atm_if_print,         DLT_ATM_RFC1483 },
 125 #ifdef DLT_C_HDLC
 126         { chdlc_if_print,       DLT_C_HDLC },
 127 #endif
 128 #ifdef DLT_HDLC
 129         { chdlc_if_print,       DLT_HDLC },
 130 #endif
 131 #ifdef DLT_PPP_SERIAL
 132         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 133 #endif
 134 #ifdef DLT_LINUX_SLL
 135         { sll_if_print,         DLT_LINUX_SLL },
 136 #endif
 137         { NULL,                 0 },
 138 };
 139
 140 static pcap_handler
 141 lookup_printer(int type)
 142 {
 143         struct printer *p;
 144
 145         for (p = printers; p->f; ++p)
 146                 if (type == p->type)
 147                         return p->f;
 148
 149         error("unknown data link type %d", type);
 150         /* NOTREACHED */
 151 }
 152
 153 static pcap_t *pd;
 154
 155 extern int optind;
 156 extern int opterr;
 157 extern char *optarg;
 158
 159 int
 160 main(int argc, char **argv)
 161 {
 162         register int cnt, op, i;
 163         bpf_u_int32 localnet, netmask;
 164         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 165         pcap_handler printer;
 166         struct bpf_program fcode;
 167         RETSIGTYPE (*oldhandler)(int);
 168         u_char *pcap_userdata;
 169         char ebuf[PCAP_ERRBUF_SIZE];
 170
 171         cnt = -1;
 172         device = NULL;
 173         infile = NULL;
 174         RFileName = NULL;
 175         WFileName = NULL;
 176         if ((cp = strrchr(argv[0], '/')) != NULL)
 177                 program_name = cp + 1;
 178         else
 179                 program_name = argv[0];
 180
 181         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 182                 error("%s", ebuf);
 183
 184 #ifdef LIBSMI
 185         smiInit("tcpdump");
 186 #endif
 187
 188         opterr = 0;
 189         while (
 190             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 191                 switch (op) {
 192
 193                 case 'a':
 194                         ++aflag;
 195                         break;
 196
 197                 case 'c':
 198                         cnt = atoi(optarg);
 199                         if (cnt <= 0)
 200                                 error("invalid packet count %s", optarg);
 201                         break;
 202
 203                 case 'd':
 204                         ++dflag;
 205                         break;
 206
 207                 case 'e':
 208                         ++eflag;
 209                         break;
 210
 211                 case 'E':
 212 #ifndef HAVE_LIBCRYPTO
 213                         warning("crypto code not compiled in");
 214 #endif
 215                         espsecret = optarg;
 216                         break;
 217
 218                 case 'f':
 219                         ++fflag;
 220                         break;
 221
 222                 case 'F':
 223                         infile = optarg;
 224                         break;
 225
 226                 case 'i':
 227                         device = optarg;
 228                         break;
 229
 230                 case 'l':
 231 #ifdef HAVE_SETLINEBUF
 232                         setlinebuf(stdout);
 233 #else
 234                         setvbuf(stdout, NULL, _IOLBF, 0);
 235 #endif
 236                         break;
 237
 238                 case 'n':
 239                         ++nflag;
 240                         break;
 241
 242                 case 'N':
 243                         ++Nflag;
 244                         break;
 245
 246                 case 'm':
 247 #ifdef LIBSMI
 248                         if (smiLoadModule(optarg) == 0) {
 249                                 error("could not load MIB module %s", optarg);
 250                         }
 251                         sflag = 1;
 252 #else
 253                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 254                                       program_name, optarg);
 255                         (void)fprintf(stderr, "(no libsmi support)\n");
 256 #endif
 257
 258                 case 'O':
 259                         Oflag = 0;
 260                         break;
 261
 262                 case 'p':
 263                         ++pflag;
 264                         break;
 265
 266                 case 'q':
 267                         ++qflag;
 268                         break;
 269
 270                 case 'r':
 271                         RFileName = optarg;
 272                         break;
 273
 274                 case 'R':
 275                         Rflag = 0;
 276                         break;
 277
 278                 case 's': {
 279                         char *end;
 280
 281                         snaplen = strtol(optarg, &end, 0);
 282                         if (optarg == end || *end != '\0'
 283                             || snaplen < 0 || snaplen > 65535)
 284                                 error("invalid snaplen %s", optarg);
 285                         else if (snaplen == 0)
 286                                 snaplen = 65535;
 287                         break;
 288                 }
 289
 290                 case 'S':
 291                         ++Sflag;
 292                         break;
 293
 294                 case 't':
 295                         --tflag;
 296                         break;
 297
 298                 case 'T':
 299                         if (strcasecmp(optarg, "vat") == 0)
 300                                 packettype = PT_VAT;
 301                         else if (strcasecmp(optarg, "wb") == 0)
 302                                 packettype = PT_WB;
 303                         else if (strcasecmp(optarg, "rpc") == 0)
 304                                 packettype = PT_RPC;
 305                         else if (strcasecmp(optarg, "rtp") == 0)
 306                                 packettype = PT_RTP;
 307                         else if (strcasecmp(optarg, "rtcp") == 0)
 308                                 packettype = PT_RTCP;
 309                         else if (strcasecmp(optarg, "snmp") == 0)
 310                                 packettype = PT_SNMP;
 311                         else if (strcasecmp(optarg, "cnfp") == 0)
 312                                 packettype = PT_CNFP;
 313                         else
 314                                 error("unknown packet type `%s'", optarg);
 315                         break;
 316
 317                 case 'u':
 318                         ++uflag;
 319                         break;
 320
 321                 case 'v':
 322                         ++vflag;
 323                         break;
 324
 325                 case 'w':
 326                         WFileName = optarg;
 327                         break;
 328
 329                 case 'x':
 330                         ++xflag;
 331                         break;
 332
 333                 case 'X':
 334                         ++xflag;
 335                         ++Xflag;
 336                         break;
 337
 338 #ifdef YYDEBUG
 339                 case 'Y':
 340                         {
 341                         /* Undocumented flag */
 342                         extern int yydebug;
 343                         yydebug = 1;
 344                         }
 345                         break;
 346 #endif
 347                 default:
 348                         usage();
 349                         /* NOTREACHED */
 350                 }
 351
 352         if (aflag && nflag)
 353                 error("-a and -n options are incompatible");
 354
 355         if (tflag > 0)
 356                 thiszone = gmt2local(0);
 357
 358         if (RFileName != NULL) {
 359                 /*
 360                  * We don't need network access, so set it back to the user id.
 361                  * Also, this prevents the user from reading anyone's
 362                  * trace file.
 363                  */
 364                 setuid(getuid());
 365
 366                 pd = pcap_open_offline(RFileName, ebuf);
 367                 if (pd == NULL)
 368                         error("%s", ebuf);
 369                 localnet = 0;
 370                 netmask = 0;
 371                 if (fflag != 0)
 372                         error("-f and -r options are incompatible");
 373         } else {
 374                 if (device == NULL) {
 375                         device = pcap_lookupdev(ebuf);
 376                         if (device == NULL)
 377                                 error("%s", ebuf);
 378                 }
 379                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 380                 if (pd == NULL)
 381                         error("%s", ebuf);
 382                 i = pcap_snapshot(pd);
 383                 if (snaplen < i) {
 384                         warning("snaplen raised from %d to %d", snaplen, i);
 385                         snaplen = i;
 386                 }
 387                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 388                         localnet = 0;
 389                         netmask = 0;
 390                         warning("%s", ebuf);
 391                 }
 392                 /*
 393                  * Let user own process after socket has been opened.
 394                  */
 395                 setuid(getuid());
 396         }
 397         if (infile)
 398                 cmdbuf = read_infile(infile);
 399         else
 400                 cmdbuf = copy_argv(&argv[optind]);
 401
 402         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 403                 error("%s", pcap_geterr(pd));
 404         if (dflag) {
 405                 bpf_dump(&fcode, dflag);
 406                 exit(0);
 407         }
 408         init_addrtoname(localnet, netmask);
 409
 410         (void)setsignal(SIGTERM, cleanup);
 411         (void)setsignal(SIGINT, cleanup);
 412         /* Cooperate with nohup(1) */
 413         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 414                 (void)setsignal(SIGHUP, oldhandler);
 415
 416         if (pcap_setfilter(pd, &fcode) < 0)
 417                 error("%s", pcap_geterr(pd));
 418         if (WFileName) {
 419                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 420                 if (p == NULL)
 421                         error("%s", pcap_geterr(pd));
 422                 printer = pcap_dump;
 423                 pcap_userdata = (u_char *)p;
 424         } else {
 425                 printer = lookup_printer(pcap_datalink(pd));
 426                 pcap_userdata = 0;
 427         }
 428         if (RFileName == NULL) {
 429                 (void)fprintf(stderr, "%s: listening on %s\n",
 430                     program_name, device);
 431                 (void)fflush(stderr);
 432         }
 433         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 434                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 435                     program_name, pcap_geterr(pd));
 436                 exit(1);
 437         }
 438         pcap_close(pd);
 439         exit(0);
 440 }
 441
 442 /* make a clean exit on interrupts */
 443 static RETSIGTYPE
 444 cleanup(int signo)
 445 {
 446         struct pcap_stat stat;
 447
 448         /* Can't print the summary if reading from a savefile */
 449         if (pd != NULL && pcap_file(pd) == NULL) {
 450                 (void)fflush(stdout);
 451                 putc('\n', stderr);
 452                 if (pcap_stats(pd, &stat) < 0)
 453                         (void)fprintf(stderr, "pcap_stats: %s\n",
 454                             pcap_geterr(pd));
 455                 else {
 456                         (void)fprintf(stderr, "%d packets received by filter\n",
 457                             stat.ps_recv);
 458                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 459                             stat.ps_drop);
 460                 }
 461         }
 462         exit(0);
 463 }
 464
 465 /* Like default_print() but data need not be aligned */
 466 void
 467 default_print_unaligned(register const u_char *cp, register u_int length)
 468 {
 469         register u_int i, s;
 470         register int nshorts;
 471
 472         if (Xflag) {
 473                 ascii_print(cp, length);
 474                 return;
 475         }
 476         nshorts = (u_int) length / sizeof(u_short);
 477         i = 0;
 478         while (--nshorts >= 0) {
 479                 if ((i++ % 8) == 0)
 480                         (void)printf("\n\t\t\t");
 481                 s = *cp++;
 482                 (void)printf(" %02x%02x", s, *cp++);
 483         }
 484         if (length & 1) {
 485                 if ((i % 8) == 0)
 486                         (void)printf("\n\t\t\t");
 487                 (void)printf(" %02x", *cp);
 488         }
 489 }
 490
 491 /*
 492  * By default, print the packet out in hex.
 493  */
 494 void
 495 default_print(register const u_char *bp, register u_int length)
 496 {
 497         default_print_unaligned(bp, length);
 498 }
 499
 500 static void
 501 usage(void)
 502 {
 503         extern char version[];
 504         extern char pcap_version[];
 505
 506         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 507         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 508         (void)fprintf(stderr,
 509 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 510         (void)fprintf(stderr,
 511 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 512         (void)fprintf(stderr,
 513 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 514         exit(-1);
 515 }