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 1.130 1999-10-17 21:37:17 mcr 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 #include <sys/types.h>
  39 #include <sys/time.h>
  40
  41 #include <netinet/in.h>
  42
  43 #include <pcap.h>
  44 #include <signal.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49
  50 #include "interface.h"
  51 #include "addrtoname.h"
  52 #include "machdep.h"
  53 #include "setsignal.h"
  54 #include "gmt2local.h"
  55
  56 int aflag;                      /* translate network and broadcast addresses */
  57 int dflag;                      /* print filter code */
  58 int eflag;                      /* print ethernet header */
  59 int fflag;                      /* don't translate "foreign" IP address */
  60 int nflag;                      /* leave addresses as numbers */
  61 int Nflag;                      /* remove domains from printed host names */
  62 int Oflag = 1;                  /* run filter code optimizer */
  63 int pflag;                      /* don't go promiscuous */
  64 int qflag;                      /* quick (shorter) output */
  65 int Sflag;                      /* print raw TCP sequence numbers */
  66 int tflag = 1;                  /* print packet arrival time */
  67 int vflag;                      /* verbose */
  68 int xflag;                      /* print packet in hex */
  69
  70 int packettype;
  71
  72
  73 char *program_name;
  74
  75 int32_t thiszone;               /* seconds offset from gmt to local time */
  76
  77 /* Externs */
  78 extern void bpf_dump(struct bpf_program *, int);
  79
  80 /* Forwards */
  81 RETSIGTYPE cleanup(int);
  82 extern __dead void usage(void) __attribute__((volatile));
  83
  84 /* Length of saved portion of packet. */
  85 int snaplen = DEFAULT_SNAPLEN;
  86
  87 struct printer {
  88         pcap_handler f;
  89         int type;
  90 };
  91
  92 static struct printer printers[] = {
  93         { ether_if_print,       DLT_EN10MB },
  94         { ether_if_print,       DLT_IEEE802 },
  95         { sl_if_print,          DLT_SLIP },
  96         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
  97         { ppp_if_print,         DLT_PPP },
  98         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
  99         { fddi_if_print,        DLT_FDDI },
 100         { null_if_print,        DLT_NULL },
 101         { raw_if_print,         DLT_RAW },
 102         { atm_if_print,         DLT_ATM_RFC1483 },
 103         { NULL,                 0 },
 104 };
 105
 106 static pcap_handler
 107 lookup_printer(int type)
 108 {
 109         struct printer *p;
 110
 111         for (p = printers; p->f; ++p)
 112                 if (type == p->type)
 113                         return p->f;
 114
 115         error("unknown data link type 0x%x", type);
 116         /* NOTREACHED */
 117 }
 118
 119 static pcap_t *pd;
 120
 121 extern int optind;
 122 extern int opterr;
 123 extern char *optarg;
 124
 125 int
 126 main(int argc, char **argv)
 127 {
 128         register int cnt, op, i;
 129         bpf_u_int32 localnet, netmask;
 130         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 131         pcap_handler printer;
 132         struct bpf_program fcode;
 133         RETSIGTYPE (*oldhandler)(int);
 134         u_char *pcap_userdata;
 135         char ebuf[PCAP_ERRBUF_SIZE];
 136
 137         cnt = -1;
 138         device = NULL;
 139         infile = NULL;
 140         RFileName = NULL;
 141         WFileName = NULL;
 142         if ((cp = strrchr(argv[0], '/')) != NULL)
 143                 program_name = cp + 1;
 144         else
 145                 program_name = argv[0];
 146
 147         if (abort_on_misalignment(ebuf) < 0)
 148                 error("%s", ebuf);
 149
 150         opterr = 0;
 151         while (
 152             (op = getopt(argc, argv, "ac:defF:i:lnNOpqr:s:StT:vw:xY")) != EOF)
 153                 switch (op) {
 154
 155                 case 'a':
 156                         ++aflag;
 157                         break;
 158
 159                 case 'c':
 160                         cnt = atoi(optarg);
 161                         if (cnt <= 0)
 162                                 error("invalid packet count %s", optarg);
 163                         break;
 164
 165                 case 'd':
 166                         ++dflag;
 167                         break;
 168
 169                 case 'e':
 170                         ++eflag;
 171                         break;
 172
 173                 case 'f':
 174                         ++fflag;
 175                         break;
 176
 177                 case 'F':
 178                         infile = optarg;
 179                         break;
 180
 181                 case 'i':
 182                         device = optarg;
 183                         break;
 184
 185                 case 'l':
 186 #ifdef HAVE_SETLINEBUF
 187                         setlinebuf(stdout);
 188 #else
 189                         setvbuf(stdout, NULL, _IOLBF, 0);
 190 #endif
 191                         break;
 192
 193                 case 'n':
 194                         ++nflag;
 195                         break;
 196
 197                 case 'N':
 198                         ++Nflag;
 199                         break;
 200
 201                 case 'O':
 202                         Oflag = 0;
 203                         break;
 204
 205                 case 'p':
 206                         ++pflag;
 207                         break;
 208
 209                 case 'q':
 210                         ++qflag;
 211                         break;
 212
 213                 case 'r':
 214                         RFileName = optarg;
 215                         break;
 216
 217                 case 's':
 218                         snaplen = atoi(optarg);
 219                         if (snaplen <= 0)
 220                                 error("invalid snaplen %s", optarg);
 221                         break;
 222
 223                 case 'S':
 224                         ++Sflag;
 225                         break;
 226
 227                 case 't':
 228                         --tflag;
 229                         break;
 230
 231                 case 'T':
 232                         if (strcasecmp(optarg, "vat") == 0)
 233                                 packettype = PT_VAT;
 234                         else if (strcasecmp(optarg, "wb") == 0)
 235                                 packettype = PT_WB;
 236                         else if (strcasecmp(optarg, "rpc") == 0)
 237                                 packettype = PT_RPC;
 238                         else if (strcasecmp(optarg, "rtp") == 0)
 239                                 packettype = PT_RTP;
 240                         else if (strcasecmp(optarg, "rtcp") == 0)
 241                                 packettype = PT_RTCP;
 242                         else if (strcasecmp(optarg, "snmp") == 0)
 243                                 packettype = PT_SNMP;
 244                         else
 245                                 error("unknown packet type `%s'", optarg);
 246                         break;
 247
 248                 case 'v':
 249                         ++vflag;
 250                         break;
 251
 252                 case 'w':
 253                         WFileName = optarg;
 254                         break;
 255 #ifdef YYDEBUG
 256                 case 'Y':
 257                         {
 258                         /* Undocumented flag */
 259                         extern int yydebug;
 260                         yydebug = 1;
 261                         }
 262                         break;
 263 #endif
 264                 case 'x':
 265                         ++xflag;
 266                         break;
 267
 268                 default:
 269                         usage();
 270                         /* NOTREACHED */
 271                 }
 272
 273         if (aflag && nflag)
 274                 error("-a and -n options are incompatible");
 275
 276         if (tflag > 0)
 277                 thiszone = gmt2local(0);
 278
 279         if (RFileName != NULL) {
 280                 /*
 281                  * We don't need network access, so set it back to the user id.
 282                  * Also, this prevents the user from reading anyone's
 283                  * trace file.
 284                  */
 285                 setuid(getuid());
 286
 287                 pd = pcap_open_offline(RFileName, ebuf);
 288                 if (pd == NULL)
 289                         error("%s", ebuf);
 290                 localnet = 0;
 291                 netmask = 0;
 292                 if (fflag != 0)
 293                         error("-f and -r options are incompatible");
 294         } else {
 295                 if (device == NULL) {
 296                         device = pcap_lookupdev(ebuf);
 297                         if (device == NULL)
 298                                 error("%s", ebuf);
 299                 }
 300                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 301                 if (pd == NULL)
 302                         error("%s", ebuf);
 303                 i = pcap_snapshot(pd);
 304                 if (snaplen < i) {
 305                         warning("snaplen raised from %d to %d", snaplen, i);
 306                         snaplen = i;
 307                 }
 308                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 309                         localnet = 0;
 310                         netmask = 0;
 311                         warning("%s", ebuf);
 312                 }
 313                 /*
 314                  * Let user own process after socket has been opened.
 315                  */
 316                 setuid(getuid());
 317         }
 318         if (infile)
 319                 cmdbuf = read_infile(infile);
 320         else
 321                 cmdbuf = copy_argv(&argv[optind]);
 322
 323         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 324                 error("%s", pcap_geterr(pd));
 325         if (dflag) {
 326                 bpf_dump(&fcode, dflag);
 327                 exit(0);
 328         }
 329         init_addrtoname(localnet, netmask);
 330
 331         (void)setsignal(SIGTERM, cleanup);
 332         (void)setsignal(SIGINT, cleanup);
 333         /* Cooperate with nohup(1) */
 334         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 335                 (void)setsignal(SIGHUP, oldhandler);
 336
 337         if (pcap_setfilter(pd, &fcode) < 0)
 338                 error("%s", pcap_geterr(pd));
 339         if (WFileName) {
 340                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 341                 if (p == NULL)
 342                         error("%s", pcap_geterr(pd));
 343                 printer = pcap_dump;
 344                 pcap_userdata = (u_char *)p;
 345         } else {
 346                 printer = lookup_printer(pcap_datalink(pd));
 347                 pcap_userdata = 0;
 348         }
 349         if (RFileName == NULL) {
 350                 (void)fprintf(stderr, "%s: listening on %s\n",
 351                     program_name, device);
 352                 (void)fflush(stderr);
 353         }
 354         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 355                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 356                     program_name, pcap_geterr(pd));
 357                 exit(1);
 358         }
 359         pcap_close(pd);
 360         exit(0);
 361 }
 362
 363 /* make a clean exit on interrupts */
 364 RETSIGTYPE
 365 cleanup(int signo)
 366 {
 367         struct pcap_stat stat;
 368
 369         /* Can't print the summary if reading from a savefile */
 370         if (pd != NULL && pcap_file(pd) == NULL) {
 371                 (void)fflush(stdout);
 372                 putc('\n', stderr);
 373                 if (pcap_stats(pd, &stat) < 0)
 374                         (void)fprintf(stderr, "pcap_stats: %s\n",
 375                             pcap_geterr(pd));
 376                 else {
 377                         (void)fprintf(stderr, "%d packets received by filter\n",
 378                             stat.ps_recv);
 379                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 380                             stat.ps_drop);
 381                 }
 382         }
 383         exit(0);
 384 }
 385
 386 /* Like default_print() but data need not be aligned */
 387 void
 388 default_print_unaligned(register const u_char *cp, register u_int length)
 389 {
 390         register u_int i, s;
 391         register int nshorts;
 392
 393         nshorts = (u_int) length / sizeof(u_short);
 394         i = 0;
 395         while (--nshorts >= 0) {
 396                 if ((i++ % 8) == 0)
 397                         (void)printf("\n\t\t\t");
 398                 s = *cp++;
 399                 (void)printf(" %02x%02x", s, *cp++);
 400         }
 401         if (length & 1) {
 402                 if ((i % 8) == 0)
 403                         (void)printf("\n\t\t\t");
 404                 (void)printf(" %02x", *cp);
 405         }
 406 }
 407
 408 /*
 409  * By default, print the packet out in hex.
 410  *
 411  * (BTW, please don't send us patches to print the packet out in ascii)
 412  */
 413 void
 414 default_print(register const u_char *bp, register u_int length)
 415 {
 416         register const u_short *sp;
 417         register u_int i;
 418         register int nshorts;
 419
 420         if ((long)bp & 1) {
 421                 default_print_unaligned(bp, length);
 422                 return;
 423         }
 424         sp = (u_short *)bp;
 425         nshorts = (u_int) length / sizeof(u_short);
 426         i = 0;
 427         while (--nshorts >= 0) {
 428                 if ((i++ % 8) == 0)
 429                         (void)printf("\n\t\t\t");
 430                 (void)printf(" %04x", ntohs(*sp++));
 431         }
 432         if (length & 1) {
 433                 if ((i % 8) == 0)
 434                         (void)printf("\n\t\t\t");
 435                 (void)printf(" %02x", *(u_char *)sp);
 436         }
 437 }
 438
 439 __dead void
 440 usage(void)
 441 {
 442         extern char version[];
 443         extern char pcap_version[];
 444
 445         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 446         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 447         (void)fprintf(stderr,
 448 "Usage: %s [-adeflnNOpqStvx] [-c count] [ -F file ]\n", program_name);
 449         (void)fprintf(stderr,
 450 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 451         (void)fprintf(stderr,
 452 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 453         exit(-1);
 454 }