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 1.153 2000-09-23 08:54:44 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 #include <netinet/in_systm.h>
  56
  57 #include "interface.h"
  58 #include "addrtoname.h"
  59 #include "machdep.h"
  60 #include "setsignal.h"
  61 #include "gmt2local.h"
  62
  63 int aflag;                      /* translate network and broadcast addresses */
  64 int dflag;                      /* print filter code */
  65 int eflag;                      /* print ethernet header */
  66 int fflag;                      /* don't translate "foreign" IP address */
  67 int nflag;                      /* leave addresses as numbers */
  68 int Nflag;                      /* remove domains from printed host names */
  69 int Oflag = 1;                  /* run filter code optimizer */
  70 int pflag;                      /* don't go promiscuous */
  71 int qflag;                      /* quick (shorter) output */
  72 int Rflag = 1;                  /* print sequence # field in AH/ESP*/
  73 int sflag = 0;                  /* use the libsmi to translate OIDs */
  74 int Sflag;                      /* print raw TCP sequence numbers */
  75 int tflag = 1;                  /* print packet arrival time */
  76 int uflag = 0;                  /* Print undecoded NFS handles */
  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 /* Forwards */
  91 static RETSIGTYPE cleanup(int);
  92 static void usage(void) __attribute__((noreturn));
  93
  94 /* Length of saved portion of packet. */
  95 int snaplen = DEFAULT_SNAPLEN;
  96
  97 struct printer {
  98         pcap_handler f;
  99         int type;
 100 };
 101
 102 /*
 103  * This table checks some DLT_* codes as well as checking PCAP_ENCAP_*
 104  * codes, so that those DLT_* codes that aren't the same on all platforms
 105  * (and thus don't have values identical to the values of the corresponding
 106  * PCAP_ENCAP_* codes) are, at least, handled on the platform that wrote
 107  * the capture file.
 108  *
 109  * (This may result in two identical entries in the table, if there's
 110  * a DLT_* code defined to have the same value as the corresponding
 111  * PCAP_ENCAP_* code.  Those duplicate entries are harmless.)
 112  */
 113 static struct printer printers[] = {
 114         /*
 115          * PCAP_ENCAP_* codes that correspond to DLT_* codes whose values
 116          * are the same on all platforms (the PCAP_ENCAP_* code values
 117          * are the same as the DLT_* code values).
 118          */
 119         { null_if_print,        PCAP_ENCAP_NULL },
 120         { ether_if_print,       PCAP_ENCAP_ETHERNET },
 121         { token_if_print,       PCAP_ENCAP_TOKEN_RING },
 122         { sl_if_print,          PCAP_ENCAP_SLIP },
 123         { ppp_if_print,         PCAP_ENCAP_PPP },
 124         { fddi_if_print,        PCAP_ENCAP_FDDI },
 125
 126         /*
 127          * DLT_* codes that aren't the same on all platforms, or that
 128          * aren't present on all platforms.
 129          */
 130 #ifdef DLT_ATM_RFC1483
 131         { atm_if_print,         DLT_ATM_RFC1483 },
 132 #endif
 133 #ifdef DLT_RAW
 134         { raw_if_print,         DLT_RAW },
 135 #endif
 136 #ifdef DLT_SLIP_BSDOS
 137         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 138 #endif
 139 #ifdef DLT_PPP_BSDOS
 140         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 141 #endif
 142 #ifdef DLT_CIP
 143         { cip_if_print,         DLT_CIP },
 144 #endif
 145 #ifdef DLT_ATM_CLIP
 146         { cip_if_print,         DLT_ATM_CLIP },
 147 #endif
 148 #ifdef DLT_LANE8023
 149         { lane_if_print,        DLT_LANE8023 },
 150 #endif
 151 #ifdef DLT_PPP_SERIAL
 152         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 153 #endif
 154
 155         /*
 156          * PCAP_ENCAP_* codes corresponding to DLT_* codes that aren't
 157          * necessarily the same on all platforms, and PCAP_ENCAP_* codes
 158          * for which there aren't DLT_* codes.
 159          */
 160         { atm_if_print,         PCAP_ENCAP_ATM_RFC1483 },
 161         { raw_if_print,         PCAP_ENCAP_RAW },
 162         { sl_bsdos_if_print,    PCAP_ENCAP_SLIP_BSDOS },
 163         { ppp_bsdos_if_print,   PCAP_ENCAP_PPP_BSDOS },
 164         { chdlc_if_print,       PCAP_ENCAP_C_HDLC },
 165         { cip_if_print,         PCAP_ENCAP_ATM_CLIP },
 166         { ppp_hdlc_if_print,    PCAP_ENCAP_PPP_HDLC },
 167         { NULL,                 0 },
 168 };
 169
 170 static pcap_handler
 171 lookup_printer(int type)
 172 {
 173         struct printer *p;
 174
 175         for (p = printers; p->f; ++p)
 176                 if (type == p->type)
 177                         return p->f;
 178
 179         error("unknown data link type %d", type);
 180         /* NOTREACHED */
 181 }
 182
 183 static pcap_t *pd;
 184
 185 extern int optind;
 186 extern int opterr;
 187 extern char *optarg;
 188
 189 int
 190 main(int argc, char **argv)
 191 {
 192         register int cnt, op, i;
 193         bpf_u_int32 localnet, netmask;
 194         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 195         pcap_handler printer;
 196         struct bpf_program fcode;
 197         RETSIGTYPE (*oldhandler)(int);
 198         u_char *pcap_userdata;
 199         char ebuf[PCAP_ERRBUF_SIZE];
 200
 201         cnt = -1;
 202         device = NULL;
 203         infile = NULL;
 204         RFileName = NULL;
 205         WFileName = NULL;
 206         if ((cp = strrchr(argv[0], '/')) != NULL)
 207                 program_name = cp + 1;
 208         else
 209                 program_name = argv[0];
 210
 211         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 212                 error("%s", ebuf);
 213
 214 #ifdef LIBSMI
 215         smiInit("tcpdump");
 216 #endif
 217
 218         opterr = 0;
 219         while (
 220             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 221                 switch (op) {
 222
 223                 case 'a':
 224                         ++aflag;
 225                         break;
 226
 227                 case 'c':
 228                         cnt = atoi(optarg);
 229                         if (cnt <= 0)
 230                                 error("invalid packet count %s", optarg);
 231                         break;
 232
 233                 case 'd':
 234                         ++dflag;
 235                         break;
 236
 237                 case 'e':
 238                         ++eflag;
 239                         break;
 240
 241                 case 'E':
 242 #ifndef HAVE_LIBCRYPTO
 243                         warning("crypto code not compiled in");
 244 #endif
 245                         espsecret = optarg;
 246                         break;
 247
 248                 case 'f':
 249                         ++fflag;
 250                         break;
 251
 252                 case 'F':
 253                         infile = optarg;
 254                         break;
 255
 256                 case 'i':
 257                         device = optarg;
 258                         break;
 259
 260                 case 'l':
 261 #ifdef HAVE_SETLINEBUF
 262                         setlinebuf(stdout);
 263 #else
 264                         setvbuf(stdout, NULL, _IOLBF, 0);
 265 #endif
 266                         break;
 267
 268                 case 'n':
 269                         ++nflag;
 270                         break;
 271
 272                 case 'N':
 273                         ++Nflag;
 274                         break;
 275
 276                 case 'm':
 277 #ifdef LIBSMI
 278                         if (smiLoadModule(optarg) == 0) {
 279                                 error("could not load MIB module %s", optarg);
 280                         }
 281                         sflag = 1;
 282 #else
 283                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 284                                       program_name, optarg);
 285                         (void)fprintf(stderr, "(no libsmi support)\n");
 286 #endif
 287
 288                 case 'O':
 289                         Oflag = 0;
 290                         break;
 291
 292                 case 'p':
 293                         ++pflag;
 294                         break;
 295
 296                 case 'q':
 297                         ++qflag;
 298                         break;
 299
 300                 case 'r':
 301                         RFileName = optarg;
 302                         break;
 303
 304                 case 'R':
 305                         Rflag = 0;
 306                         break;
 307
 308                 case 's': {
 309                         char *end;
 310
 311                         snaplen = strtol(optarg, &end, 0);
 312                         if (optarg == end || *end != '\0'
 313                             || snaplen < 0 || snaplen > 65535)
 314                                 error("invalid snaplen %s", optarg);
 315                         else if (snaplen == 0)
 316                                 snaplen = 65535;
 317                         break;
 318                 }
 319
 320                 case 'S':
 321                         ++Sflag;
 322                         break;
 323
 324                 case 't':
 325                         --tflag;
 326                         break;
 327
 328                 case 'T':
 329                         if (strcasecmp(optarg, "vat") == 0)
 330                                 packettype = PT_VAT;
 331                         else if (strcasecmp(optarg, "wb") == 0)
 332                                 packettype = PT_WB;
 333                         else if (strcasecmp(optarg, "rpc") == 0)
 334                                 packettype = PT_RPC;
 335                         else if (strcasecmp(optarg, "rtp") == 0)
 336                                 packettype = PT_RTP;
 337                         else if (strcasecmp(optarg, "rtcp") == 0)
 338                                 packettype = PT_RTCP;
 339                         else if (strcasecmp(optarg, "snmp") == 0)
 340                                 packettype = PT_SNMP;
 341                         else if (strcasecmp(optarg, "cnfp") == 0)
 342                                 packettype = PT_CNFP;
 343                         else
 344                                 error("unknown packet type `%s'", optarg);
 345                         break;
 346
 347                 case 'u':
 348                         ++uflag;
 349                         break;
 350
 351                 case 'v':
 352                         ++vflag;
 353                         break;
 354
 355                 case 'w':
 356                         WFileName = optarg;
 357                         break;
 358
 359                 case 'x':
 360                         ++xflag;
 361                         break;
 362
 363                 case 'X':
 364                         ++xflag;
 365                         ++Xflag;
 366                         break;
 367
 368 #ifdef YYDEBUG
 369                 case 'Y':
 370                         {
 371                         /* Undocumented flag */
 372                         extern int yydebug;
 373                         yydebug = 1;
 374                         }
 375                         break;
 376 #endif
 377                 default:
 378                         usage();
 379                         /* NOTREACHED */
 380                 }
 381
 382         if (aflag && nflag)
 383                 error("-a and -n options are incompatible");
 384
 385         if (tflag > 0)
 386                 thiszone = gmt2local(0);
 387
 388         if (RFileName != NULL) {
 389                 /*
 390                  * We don't need network access, so set it back to the user id.
 391                  * Also, this prevents the user from reading anyone's
 392                  * trace file.
 393                  */
 394                 setuid(getuid());
 395
 396                 pd = pcap_open_offline(RFileName, ebuf);
 397                 if (pd == NULL)
 398                         error("%s", ebuf);
 399                 localnet = 0;
 400                 netmask = 0;
 401                 if (fflag != 0)
 402                         error("-f and -r options are incompatible");
 403         } else {
 404                 if (device == NULL) {
 405                         device = pcap_lookupdev(ebuf);
 406                         if (device == NULL)
 407                                 error("%s", ebuf);
 408                 }
 409                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 410                 if (pd == NULL)
 411                         error("%s", ebuf);
 412                 i = pcap_snapshot(pd);
 413                 if (snaplen < i) {
 414                         warning("snaplen raised from %d to %d", snaplen, i);
 415                         snaplen = i;
 416                 }
 417                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 418                         localnet = 0;
 419                         netmask = 0;
 420                         warning("%s", ebuf);
 421                 }
 422                 /*
 423                  * Let user own process after socket has been opened.
 424                  */
 425                 setuid(getuid());
 426         }
 427         if (infile)
 428                 cmdbuf = read_infile(infile);
 429         else
 430                 cmdbuf = copy_argv(&argv[optind]);
 431
 432         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 433                 error("%s", pcap_geterr(pd));
 434         if (dflag) {
 435                 bpf_dump(&fcode, dflag);
 436                 exit(0);
 437         }
 438         init_addrtoname(localnet, netmask);
 439
 440         (void)setsignal(SIGTERM, cleanup);
 441         (void)setsignal(SIGINT, cleanup);
 442         /* Cooperate with nohup(1) */
 443         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 444                 (void)setsignal(SIGHUP, oldhandler);
 445
 446         if (pcap_setfilter(pd, &fcode) < 0)
 447                 error("%s", pcap_geterr(pd));
 448         if (WFileName) {
 449                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 450                 if (p == NULL)
 451                         error("%s", pcap_geterr(pd));
 452                 printer = pcap_dump;
 453                 pcap_userdata = (u_char *)p;
 454         } else {
 455                 printer = lookup_printer(pcap_datalink(pd));
 456                 pcap_userdata = 0;
 457         }
 458         if (RFileName == NULL) {
 459                 (void)fprintf(stderr, "%s: listening on %s\n",
 460                     program_name, device);
 461                 (void)fflush(stderr);
 462         }
 463         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 464                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 465                     program_name, pcap_geterr(pd));
 466                 exit(1);
 467         }
 468         pcap_close(pd);
 469         exit(0);
 470 }
 471
 472 /* make a clean exit on interrupts */
 473 static RETSIGTYPE
 474 cleanup(int signo)
 475 {
 476         struct pcap_stat stat;
 477
 478         /* Can't print the summary if reading from a savefile */
 479         if (pd != NULL && pcap_file(pd) == NULL) {
 480                 (void)fflush(stdout);
 481                 putc('\n', stderr);
 482                 if (pcap_stats(pd, &stat) < 0)
 483                         (void)fprintf(stderr, "pcap_stats: %s\n",
 484                             pcap_geterr(pd));
 485                 else {
 486                         (void)fprintf(stderr, "%d packets received by filter\n",
 487                             stat.ps_recv);
 488                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 489                             stat.ps_drop);
 490                 }
 491         }
 492         exit(0);
 493 }
 494
 495 /* Like default_print() but data need not be aligned */
 496 void
 497 default_print_unaligned(register const u_char *cp, register u_int length)
 498 {
 499         register u_int i, s;
 500         register int nshorts;
 501
 502         if (Xflag) {
 503                 ascii_print(cp, length);
 504                 return;
 505         }
 506         nshorts = (u_int) length / sizeof(u_short);
 507         i = 0;
 508         while (--nshorts >= 0) {
 509                 if ((i++ % 8) == 0)
 510                         (void)printf("\n\t\t\t");
 511                 s = *cp++;
 512                 (void)printf(" %02x%02x", s, *cp++);
 513         }
 514         if (length & 1) {
 515                 if ((i % 8) == 0)
 516                         (void)printf("\n\t\t\t");
 517                 (void)printf(" %02x", *cp);
 518         }
 519 }
 520
 521 /*
 522  * By default, print the packet out in hex.
 523  */
 524 void
 525 default_print(register const u_char *bp, register u_int length)
 526 {
 527         default_print_unaligned(bp, length);
 528 }
 529
 530 static void
 531 usage(void)
 532 {
 533         extern char version[];
 534         extern char pcap_version[];
 535
 536         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 537         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 538         (void)fprintf(stderr,
 539 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 540         (void)fprintf(stderr,
 541 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 542         (void)fprintf(stderr,
 543 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 544         exit(-1);
 545 }