The Tcpdump Group git mirrors - tcpdump/blob - tcpdump.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
   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, 2000\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 1.166 2001-07-04 22:03:13 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 int infodelay;
  85 int infoprint;
  86
  87 char *program_name;
  88
  89 int32_t thiszone;               /* seconds offset from gmt to local time */
  90
  91 /* Forwards */
  92 static RETSIGTYPE cleanup(int);
  93 static void usage(void) __attribute__((noreturn));
  94 #ifdef SIGINFO
  95 RETSIGTYPE requestinfo(int);
  96 #endif
  97
  98 /* Length of saved portion of packet. */
  99 int snaplen = DEFAULT_SNAPLEN;
 100
 101 struct printer {
 102         pcap_handler f;
 103         int type;
 104 };
 105
 106 static struct printer printers[] = {
 107         { arcnet_if_print,      DLT_ARCNET },
 108         { ether_if_print,       DLT_EN10MB },
 109         { token_if_print,       DLT_IEEE802 },
 110 #ifdef DLT_LANE8023
 111         { lane_if_print,        DLT_LANE8023 },
 112 #endif
 113 #ifdef DLT_CIP
 114         { cip_if_print,         DLT_CIP },
 115 #endif
 116 #ifdef DLT_ATM_CLIP
 117         { cip_if_print,         DLT_ATM_CLIP },
 118 #endif
 119         { sl_if_print,          DLT_SLIP },
 120         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 121         { ppp_if_print,         DLT_PPP },
 122         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 123         { fddi_if_print,        DLT_FDDI },
 124         { null_if_print,        DLT_NULL },
 125 #ifdef DLT_LOOP
 126         { null_if_print,        DLT_LOOP },
 127 #endif
 128         { raw_if_print,         DLT_RAW },
 129         { atm_if_print,         DLT_ATM_RFC1483 },
 130 #ifdef DLT_C_HDLC
 131         { chdlc_if_print,       DLT_C_HDLC },
 132 #endif
 133 #ifdef DLT_HDLC
 134         { chdlc_if_print,       DLT_HDLC },
 135 #endif
 136 #ifdef DLT_PPP_SERIAL
 137         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 138 #endif
 139 #ifdef DLT_PPP_ETHER
 140         { pppoe_if_print,       DLT_PPP_ETHER },
 141 #endif
 142 #ifdef DLT_LINUX_SLL
 143         { sll_if_print,         DLT_LINUX_SLL },
 144 #endif
 145 #ifdef DLT_IEEE802_11
 146         { ieee802_11_if_print,  DLT_IEEE802_11},
 147 #endif
 148 #ifdef DLT_LTALK
 149         { ltalk_if_print,       DLT_LTALK },
 150 #endif
 151         { NULL,                 0 },
 152 };
 153
 154 static pcap_handler
 155 lookup_printer(int type)
 156 {
 157         struct printer *p;
 158
 159         for (p = printers; p->f; ++p)
 160                 if (type == p->type)
 161                         return p->f;
 162
 163         error("unknown data link type %d", type);
 164         /* NOTREACHED */
 165 }
 166
 167 static pcap_t *pd;
 168
 169 extern int optind;
 170 extern int opterr;
 171 extern char *optarg;
 172
 173 int
 174 main(int argc, char **argv)
 175 {
 176         register int cnt, op, i;
 177         bpf_u_int32 localnet, netmask;
 178         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 179         pcap_handler printer;
 180         struct bpf_program fcode;
 181         RETSIGTYPE (*oldhandler)(int);
 182         u_char *pcap_userdata;
 183         char ebuf[PCAP_ERRBUF_SIZE];
 184
 185         cnt = -1;
 186         device = NULL;
 187         infile = NULL;
 188         RFileName = NULL;
 189         WFileName = NULL;
 190         if ((cp = strrchr(argv[0], '/')) != NULL)
 191                 program_name = cp + 1;
 192         else
 193                 program_name = argv[0];
 194
 195         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 196                 error("%s", ebuf);
 197
 198 #ifdef LIBSMI
 199         smiInit("tcpdump");
 200 #endif
 201
 202         opterr = 0;
 203         while (
 204             (op = getopt(argc, argv, "ac:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 205                 switch (op) {
 206
 207                 case 'a':
 208                         ++aflag;
 209                         break;
 210
 211                 case 'c':
 212                         cnt = atoi(optarg);
 213                         if (cnt <= 0)
 214                                 error("invalid packet count %s", optarg);
 215                         break;
 216
 217                 case 'd':
 218                         ++dflag;
 219                         break;
 220
 221                 case 'e':
 222                         ++eflag;
 223                         break;
 224
 225                 case 'E':
 226 #ifndef HAVE_LIBCRYPTO
 227                         warning("crypto code not compiled in");
 228 #endif
 229                         espsecret = optarg;
 230                         break;
 231
 232                 case 'f':
 233                         ++fflag;
 234                         break;
 235
 236                 case 'F':
 237                         infile = optarg;
 238                         break;
 239
 240                 case 'i':
 241                         device = optarg;
 242                         break;
 243
 244                 case 'l':
 245 #ifdef HAVE_SETLINEBUF
 246                         setlinebuf(stdout);
 247 #else
 248                         setvbuf(stdout, NULL, _IOLBF, 0);
 249 #endif
 250                         break;
 251
 252                 case 'n':
 253                         ++nflag;
 254                         break;
 255
 256                 case 'N':
 257                         ++Nflag;
 258                         break;
 259
 260                 case 'm':
 261 #ifdef LIBSMI
 262                         if (smiLoadModule(optarg) == 0) {
 263                                 error("could not load MIB module %s", optarg);
 264                         }
 265                         sflag = 1;
 266 #else
 267                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 268                                       program_name, optarg);
 269                         (void)fprintf(stderr, "(no libsmi support)\n");
 270 #endif
 271
 272                 case 'O':
 273                         Oflag = 0;
 274                         break;
 275
 276                 case 'p':
 277                         ++pflag;
 278                         break;
 279
 280                 case 'q':
 281                         ++qflag;
 282                         break;
 283
 284                 case 'r':
 285                         RFileName = optarg;
 286                         break;
 287
 288                 case 'R':
 289                         Rflag = 0;
 290                         break;
 291
 292                 case 's': {
 293                         char *end;
 294
 295                         snaplen = strtol(optarg, &end, 0);
 296                         if (optarg == end || *end != '\0'
 297                             || snaplen < 0 || snaplen > 65535)
 298                                 error("invalid snaplen %s", optarg);
 299                         else if (snaplen == 0)
 300                                 snaplen = 65535;
 301                         break;
 302                 }
 303
 304                 case 'S':
 305                         ++Sflag;
 306                         break;
 307
 308                 case 't':
 309                         --tflag;
 310                         break;
 311
 312                 case 'T':
 313                         if (strcasecmp(optarg, "vat") == 0)
 314                                 packettype = PT_VAT;
 315                         else if (strcasecmp(optarg, "wb") == 0)
 316                                 packettype = PT_WB;
 317                         else if (strcasecmp(optarg, "rpc") == 0)
 318                                 packettype = PT_RPC;
 319                         else if (strcasecmp(optarg, "rtp") == 0)
 320                                 packettype = PT_RTP;
 321                         else if (strcasecmp(optarg, "rtcp") == 0)
 322                                 packettype = PT_RTCP;
 323                         else if (strcasecmp(optarg, "snmp") == 0)
 324                                 packettype = PT_SNMP;
 325                         else if (strcasecmp(optarg, "cnfp") == 0)
 326                                 packettype = PT_CNFP;
 327                         else
 328                                 error("unknown packet type `%s'", optarg);
 329                         break;
 330
 331                 case 'u':
 332                         ++uflag;
 333                         break;
 334
 335                 case 'v':
 336                         ++vflag;
 337                         break;
 338
 339                 case 'w':
 340                         WFileName = optarg;
 341                         break;
 342
 343                 case 'x':
 344                         ++xflag;
 345                         break;
 346
 347                 case 'X':
 348                         ++xflag;
 349                         ++Xflag;
 350                         break;
 351
 352 #ifdef YYDEBUG
 353                 case 'Y':
 354                         {
 355                         /* Undocumented flag */
 356                         extern int yydebug;
 357                         yydebug = 1;
 358                         }
 359                         break;
 360 #endif
 361                 default:
 362                         usage();
 363                         /* NOTREACHED */
 364                 }
 365
 366         if (aflag && nflag)
 367                 error("-a and -n options are incompatible");
 368
 369         if (tflag > 0)
 370                 thiszone = gmt2local(0);
 371
 372         if (RFileName != NULL) {
 373                 /*
 374                  * We don't need network access, so set it back to the user id.
 375                  * Also, this prevents the user from reading anyone's
 376                  * trace file.
 377                  */
 378                 setuid(getuid());
 379
 380                 pd = pcap_open_offline(RFileName, ebuf);
 381                 if (pd == NULL)
 382                         error("%s", ebuf);
 383                 localnet = 0;
 384                 netmask = 0;
 385                 if (fflag != 0)
 386                         error("-f and -r options are incompatible");
 387         } else {
 388                 if (device == NULL) {
 389                         device = pcap_lookupdev(ebuf);
 390                         if (device == NULL)
 391                                 error("%s", ebuf);
 392                 }
 393                 *ebuf = '\0';
 394                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 395                 if (pd == NULL)
 396                         error("%s", ebuf);
 397                 else if (*ebuf)
 398                         warning("%s", ebuf);
 399                 i = pcap_snapshot(pd);
 400                 if (snaplen < i) {
 401                         warning("snaplen raised from %d to %d", snaplen, i);
 402                         snaplen = i;
 403                 }
 404                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 405                         localnet = 0;
 406                         netmask = 0;
 407                         warning("%s", ebuf);
 408                 }
 409                 /*
 410                  * Let user own process after socket has been opened.
 411                  */
 412                 setuid(getuid());
 413         }
 414         if (infile)
 415                 cmdbuf = read_infile(infile);
 416         else
 417                 cmdbuf = copy_argv(&argv[optind]);
 418
 419         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 420                 error("%s", pcap_geterr(pd));
 421         if (dflag) {
 422                 bpf_dump(&fcode, dflag);
 423                 exit(0);
 424         }
 425         init_addrtoname(localnet, netmask);
 426
 427         (void)setsignal(SIGTERM, cleanup);
 428         (void)setsignal(SIGINT, cleanup);
 429         /* Cooperate with nohup(1) */
 430         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 431                 (void)setsignal(SIGHUP, oldhandler);
 432
 433         if (pcap_setfilter(pd, &fcode) < 0)
 434                 error("%s", pcap_geterr(pd));
 435         if (WFileName) {
 436                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 437                 if (p == NULL)
 438                         error("%s", pcap_geterr(pd));
 439                 printer = pcap_dump;
 440                 pcap_userdata = (u_char *)p;
 441         } else {
 442                 printer = lookup_printer(pcap_datalink(pd));
 443                 pcap_userdata = 0;
 444 #ifdef SIGINFO
 445                 (void)setsignal(SIGINFO, requestinfo);
 446 #endif
 447         }
 448         if (RFileName == NULL) {
 449                 (void)fprintf(stderr, "%s: listening on %s\n",
 450                     program_name, device);
 451                 (void)fflush(stderr);
 452         }
 453         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 454                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 455                     program_name, pcap_geterr(pd));
 456                 exit(1);
 457         }
 458         pcap_close(pd);
 459         exit(0);
 460 }
 461
 462 /* make a clean exit on interrupts */
 463 static RETSIGTYPE
 464 cleanup(int signo)
 465 {
 466
 467         /* Can't print the summary if reading from a savefile */
 468         if (pd != NULL && pcap_file(pd) == NULL) {
 469                 (void)fflush(stdout);
 470                 putc('\n', stderr);
 471                 info(1);
 472         }
 473         exit(0);
 474 }
 475
 476 void
 477 info(register int verbose)
 478 {
 479         struct pcap_stat stat;
 480
 481         if (pcap_stats(pd, &stat) < 0) {
 482                 (void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
 483                 return;
 484         }
 485         if (!verbose)
 486                 fprintf(stderr, "%s: ", program_name);
 487         (void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
 488         if (!verbose)
 489                 fputs(", ", stderr);
 490         else
 491                 putc('\n', stderr);
 492         (void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
 493         infoprint = 0;
 494 }
 495
 496 /* Like default_print() but data need not be aligned */
 497 void
 498 default_print_unaligned(register const u_char *cp, register u_int length)
 499 {
 500         register u_int i, s;
 501         register int nshorts;
 502
 503         if (Xflag) {
 504                 ascii_print(cp, length);
 505                 return;
 506         }
 507         nshorts = (u_int) length / sizeof(u_short);
 508         i = 0;
 509         while (--nshorts >= 0) {
 510                 if ((i++ % 8) == 0)
 511                         (void)printf("\n\t\t\t");
 512                 s = *cp++;
 513                 (void)printf(" %02x%02x", s, *cp++);
 514         }
 515         if (length & 1) {
 516                 if ((i % 8) == 0)
 517                         (void)printf("\n\t\t\t");
 518                 (void)printf(" %02x", *cp);
 519         }
 520 }
 521
 522 /*
 523  * By default, print the packet out in hex.
 524  */
 525 void
 526 default_print(register const u_char *bp, register u_int length)
 527 {
 528         default_print_unaligned(bp, length);
 529 }
 530
 531 #ifdef SIGINFO
 532 RETSIGTYPE requestinfo(int signo)
 533 {
 534         if (infodelay)
 535                 ++infoprint;
 536         else
 537                 info(0);
 538 }
 539 #endif
 540
 541 static void
 542 usage(void)
 543 {
 544         extern char version[];
 545         extern char pcap_version[];
 546
 547         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 548         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 549         (void)fprintf(stderr,
 550 "Usage: %s [-adeflnNOpqStuvxX] [-c count] [ -F file ]\n", program_name);
 551         (void)fprintf(stderr,
 552 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 553         (void)fprintf(stderr,
 554 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 555         exit(1);
 556 }