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  * Support for splitting captures into multiple files with a maximum
  22  * file size:
  23  *
  24  * Copyright (c) 2001
  25  *      Seth Webster <swebster@sst.ll.mit.edu>
  26  */
  27
  28 #ifndef lint
  29 static const char copyright[] =
  30     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
  31 The Regents of the University of California.  All rights reserved.\n";
  32 static const char rcsid[] =
  33     "@(#) $Header: /tcpdump/master/tcpdump/tcpdump.c,v 1.174 2002-02-05 10:07:40 guy Exp $ (LBL)";
  34 #endif
  35
  36 /*
  37  * tcpdump - monitor tcp/ip traffic on an ethernet.
  38  *
  39  * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory.
  40  * Mercilessly hacked and occasionally improved since then via the
  41  * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
  42  */
  43
  44 #ifdef HAVE_CONFIG_H
  45 #include "config.h"
  46 #endif
  47
  48 #include <sys/types.h>
  49 #include <sys/time.h>
  50
  51 #include <netinet/in.h>
  52
  53 #include <pcap.h>
  54 #include <signal.h>
  55 #include <stdio.h>
  56 #include <stdlib.h>
  57 #include <string.h>
  58 #include <unistd.h>
  59 #include <ctype.h>
  60
  61
  62 #include "interface.h"
  63 #include "addrtoname.h"
  64 #include "machdep.h"
  65 #include "setsignal.h"
  66 #include "gmt2local.h"
  67
  68 int aflag;                      /* translate network and broadcast addresses */
  69 int dflag;                      /* print filter code */
  70 int eflag;                      /* print ethernet header */
  71 int fflag;                      /* don't translate "foreign" IP address */
  72 int nflag;                      /* leave addresses as numbers */
  73 int Nflag;                      /* remove domains from printed host names */
  74 int Oflag = 1;                  /* run filter code optimizer */
  75 int pflag;                      /* don't go promiscuous */
  76 int qflag;                      /* quick (shorter) output */
  77 int Rflag = 1;                  /* print sequence # field in AH/ESP*/
  78 int sflag = 0;                  /* use the libsmi to translate OIDs */
  79 int Sflag;                      /* print raw TCP sequence numbers */
  80 int tflag = 1;                  /* print packet arrival time */
  81 int uflag = 0;                  /* Print undecoded NFS handles */
  82 int vflag;                      /* verbose */
  83 int xflag;                      /* print packet in hex */
  84 int Xflag;                      /* print packet in ascii as well as hex */
  85 off_t Cflag = 0;                /* rotate dump files after this many bytes */
  86
  87 char *espsecret = NULL;         /* ESP secret key */
  88
  89 int packettype;
  90
  91 int infodelay;
  92 int infoprint;
  93
  94 char *program_name;
  95
  96 int32_t thiszone;               /* seconds offset from gmt to local time */
  97
  98 /* Forwards */
  99 static RETSIGTYPE cleanup(int);
 100 static void usage(void) __attribute__((noreturn));
 101
 102 static void dump_and_trunc(u_char *, const struct pcap_pkthdr *, const u_char *);
 103
 104 #ifdef SIGINFO
 105 RETSIGTYPE requestinfo(int);
 106 #endif
 107
 108 /* Length of saved portion of packet. */
 109 int snaplen = DEFAULT_SNAPLEN;
 110
 111 struct printer {
 112         pcap_handler f;
 113         int type;
 114 };
 115
 116 static struct printer printers[] = {
 117         { arcnet_if_print,      DLT_ARCNET },
 118         { ether_if_print,       DLT_EN10MB },
 119         { token_if_print,       DLT_IEEE802 },
 120 #ifdef DLT_LANE8023
 121         { lane_if_print,        DLT_LANE8023 },
 122 #endif
 123 #ifdef DLT_CIP
 124         { cip_if_print,         DLT_CIP },
 125 #endif
 126 #ifdef DLT_ATM_CLIP
 127         { cip_if_print,         DLT_ATM_CLIP },
 128 #endif
 129         { sl_if_print,          DLT_SLIP },
 130         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 131         { ppp_if_print,         DLT_PPP },
 132         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 133         { fddi_if_print,        DLT_FDDI },
 134         { null_if_print,        DLT_NULL },
 135 #ifdef DLT_LOOP
 136         { null_if_print,        DLT_LOOP },
 137 #endif
 138         { raw_if_print,         DLT_RAW },
 139         { atm_if_print,         DLT_ATM_RFC1483 },
 140 #ifdef DLT_C_HDLC
 141         { chdlc_if_print,       DLT_C_HDLC },
 142 #endif
 143 #ifdef DLT_HDLC
 144         { chdlc_if_print,       DLT_HDLC },
 145 #endif
 146 #ifdef DLT_PPP_SERIAL
 147         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 148 #endif
 149 #ifdef DLT_PPP_ETHER
 150         { pppoe_if_print,       DLT_PPP_ETHER },
 151 #endif
 152 #ifdef DLT_LINUX_SLL
 153         { sll_if_print,         DLT_LINUX_SLL },
 154 #endif
 155 #ifdef DLT_IEEE802_11
 156         { ieee802_11_if_print,  DLT_IEEE802_11},
 157 #endif
 158 #ifdef DLT_LTALK
 159         { ltalk_if_print,       DLT_LTALK },
 160 #endif
 161 #ifdef DLT_PFLOG
 162         { pflog_if_print,       DLT_PFLOG },
 163 #endif
 164         { NULL,                 0 },
 165 };
 166
 167 static pcap_handler
 168 lookup_printer(int type)
 169 {
 170         struct printer *p;
 171
 172         for (p = printers; p->f; ++p)
 173                 if (type == p->type)
 174                         return p->f;
 175
 176         error("unknown data link type %d", type);
 177         /* NOTREACHED */
 178 }
 179
 180 static pcap_t *pd;
 181
 182 extern int optind;
 183 extern int opterr;
 184 extern char *optarg;
 185
 186 struct dump_info {
 187         char    *WFileName;
 188         pcap_t  *pd;
 189         pcap_dumper_t *p;
 190 };
 191
 192 int
 193 main(int argc, char **argv)
 194 {
 195         register int cnt, op, i;
 196         bpf_u_int32 localnet, netmask;
 197         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 198         pcap_handler printer;
 199         struct bpf_program fcode;
 200         RETSIGTYPE (*oldhandler)(int);
 201         struct dump_info dumpinfo;
 202         u_char *pcap_userdata;
 203         char ebuf[PCAP_ERRBUF_SIZE];
 204
 205         cnt = -1;
 206         device = NULL;
 207         infile = NULL;
 208         RFileName = NULL;
 209         WFileName = NULL;
 210         if ((cp = strrchr(argv[0], '/')) != NULL)
 211                 program_name = cp + 1;
 212         else
 213                 program_name = argv[0];
 214
 215         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 216                 error("%s", ebuf);
 217
 218 #ifdef LIBSMI
 219         smiInit("tcpdump");
 220 #endif
 221
 222         opterr = 0;
 223         while (
 224             (op = getopt(argc, argv, "ac:C:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 225                 switch (op) {
 226
 227                 case 'a':
 228                         ++aflag;
 229                         break;
 230
 231                 case 'c':
 232                         cnt = atoi(optarg);
 233                         if (cnt <= 0)
 234                                 error("invalid packet count %s", optarg);
 235                         break;
 236
 237                 case 'C':
 238                         Cflag = atoi(optarg) * 1000000;
 239                         if (Cflag < 0)
 240                                 error("invalid file size %s", optarg);
 241                         break;
 242
 243                 case 'd':
 244                         ++dflag;
 245                         break;
 246
 247                 case 'e':
 248                         ++eflag;
 249                         break;
 250
 251                 case 'E':
 252 #ifndef HAVE_LIBCRYPTO
 253                         warning("crypto code not compiled in");
 254 #endif
 255                         espsecret = optarg;
 256                         break;
 257
 258                 case 'f':
 259                         ++fflag;
 260                         break;
 261
 262                 case 'F':
 263                         infile = optarg;
 264                         break;
 265
 266                 case 'i':
 267                         device = optarg;
 268                         break;
 269
 270                 case 'l':
 271 #ifdef HAVE_SETLINEBUF
 272                         setlinebuf(stdout);
 273 #else
 274                         setvbuf(stdout, NULL, _IOLBF, 0);
 275 #endif
 276                         break;
 277
 278                 case 'n':
 279                         ++nflag;
 280                         break;
 281
 282                 case 'N':
 283                         ++Nflag;
 284                         break;
 285
 286                 case 'm':
 287 #ifdef LIBSMI
 288                         if (smiLoadModule(optarg) == 0) {
 289                                 error("could not load MIB module %s", optarg);
 290                         }
 291                         sflag = 1;
 292 #else
 293                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 294                                       program_name, optarg);
 295                         (void)fprintf(stderr, "(no libsmi support)\n");
 296 #endif
 297
 298                 case 'O':
 299                         Oflag = 0;
 300                         break;
 301
 302                 case 'p':
 303                         ++pflag;
 304                         break;
 305
 306                 case 'q':
 307                         ++qflag;
 308                         break;
 309
 310                 case 'r':
 311                         RFileName = optarg;
 312                         break;
 313
 314                 case 'R':
 315                         Rflag = 0;
 316                         break;
 317
 318                 case 's': {
 319                         char *end;
 320
 321                         snaplen = strtol(optarg, &end, 0);
 322                         if (optarg == end || *end != '\0'
 323                             || snaplen < 0 || snaplen > 65535)
 324                                 error("invalid snaplen %s", optarg);
 325                         else if (snaplen == 0)
 326                                 snaplen = 65535;
 327                         break;
 328                 }
 329
 330                 case 'S':
 331                         ++Sflag;
 332                         break;
 333
 334                 case 't':
 335                         --tflag;
 336                         break;
 337
 338                 case 'T':
 339                         if (strcasecmp(optarg, "vat") == 0)
 340                                 packettype = PT_VAT;
 341                         else if (strcasecmp(optarg, "wb") == 0)
 342                                 packettype = PT_WB;
 343                         else if (strcasecmp(optarg, "rpc") == 0)
 344                                 packettype = PT_RPC;
 345                         else if (strcasecmp(optarg, "rtp") == 0)
 346                                 packettype = PT_RTP;
 347                         else if (strcasecmp(optarg, "rtcp") == 0)
 348                                 packettype = PT_RTCP;
 349                         else if (strcasecmp(optarg, "snmp") == 0)
 350                                 packettype = PT_SNMP;
 351                         else if (strcasecmp(optarg, "cnfp") == 0)
 352                                 packettype = PT_CNFP;
 353                         else
 354                                 error("unknown packet type `%s'", optarg);
 355                         break;
 356
 357                 case 'u':
 358                         ++uflag;
 359                         break;
 360
 361                 case 'v':
 362                         ++vflag;
 363                         break;
 364
 365                 case 'w':
 366                         WFileName = optarg;
 367                         break;
 368
 369                 case 'x':
 370                         ++xflag;
 371                         break;
 372
 373                 case 'X':
 374                         ++xflag;
 375                         ++Xflag;
 376                         break;
 377
 378 #ifdef YYDEBUG
 379                 case 'Y':
 380                         {
 381                         /* Undocumented flag */
 382                         extern int yydebug;
 383                         yydebug = 1;
 384                         }
 385                         break;
 386 #endif
 387                 default:
 388                         usage();
 389                         /* NOTREACHED */
 390                 }
 391
 392         if (aflag && nflag)
 393                 error("-a and -n options are incompatible");
 394
 395         if (tflag > 0)
 396                 thiszone = gmt2local(0);
 397
 398         if (RFileName != NULL) {
 399                 /*
 400                  * We don't need network access, so set it back to the user id.
 401                  * Also, this prevents the user from reading anyone's
 402                  * trace file.
 403                  */
 404                 setuid(getuid());
 405
 406                 pd = pcap_open_offline(RFileName, ebuf);
 407                 if (pd == NULL)
 408                         error("%s", ebuf);
 409                 localnet = 0;
 410                 netmask = 0;
 411                 if (fflag != 0)
 412                         error("-f and -r options are incompatible");
 413         } else {
 414                 if (device == NULL) {
 415                         device = pcap_lookupdev(ebuf);
 416                         if (device == NULL)
 417                                 error("%s", ebuf);
 418                 }
 419                 *ebuf = '\0';
 420                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 421                 if (pd == NULL)
 422                         error("%s", ebuf);
 423                 else if (*ebuf)
 424                         warning("%s", ebuf);
 425                 i = pcap_snapshot(pd);
 426                 if (snaplen < i) {
 427                         warning("snaplen raised from %d to %d", snaplen, i);
 428                         snaplen = i;
 429                 }
 430                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 431                         localnet = 0;
 432                         netmask = 0;
 433                         warning("%s", ebuf);
 434                 }
 435                 /*
 436                  * Let user own process after socket has been opened.
 437                  */
 438                 setuid(getuid());
 439         }
 440         if (infile)
 441                 cmdbuf = read_infile(infile);
 442         else
 443                 cmdbuf = copy_argv(&argv[optind]);
 444
 445         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 446                 error("%s", pcap_geterr(pd));
 447         if (dflag) {
 448                 bpf_dump(&fcode, dflag);
 449                 exit(0);
 450         }
 451         init_addrtoname(localnet, netmask);
 452
 453         (void)setsignal(SIGTERM, cleanup);
 454         (void)setsignal(SIGINT, cleanup);
 455         /* Cooperate with nohup(1) */
 456         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 457                 (void)setsignal(SIGHUP, oldhandler);
 458
 459         if (pcap_setfilter(pd, &fcode) < 0)
 460                 error("%s", pcap_geterr(pd));
 461         if (WFileName) {
 462                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 463                 if (p == NULL)
 464                         error("%s", pcap_geterr(pd));
 465                 if (Cflag != 0) {
 466                         printer = dump_and_trunc;
 467                         dumpinfo.WFileName = WFileName;
 468                         dumpinfo.pd = pd;
 469                         dumpinfo.p = p;
 470                         pcap_userdata = (u_char *)&dumpinfo;
 471                 } else {
 472                         printer = pcap_dump;
 473                         pcap_userdata = (u_char *)p;
 474                 }
 475         } else {
 476                 printer = lookup_printer(pcap_datalink(pd));
 477                 pcap_userdata = 0;
 478 #ifdef SIGINFO
 479                 (void)setsignal(SIGINFO, requestinfo);
 480 #endif
 481         }
 482         if (RFileName == NULL) {
 483                 (void)fprintf(stderr, "%s: listening on %s\n",
 484                     program_name, device);
 485                 (void)fflush(stderr);
 486         }
 487         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 488                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 489                     program_name, pcap_geterr(pd));
 490                 exit(1);
 491         }
 492         if (RFileName == NULL)
 493                 info(1);
 494         pcap_close(pd);
 495         exit(0);
 496 }
 497
 498 /* make a clean exit on interrupts */
 499 static RETSIGTYPE
 500 cleanup(int signo)
 501 {
 502
 503         /* Can't print the summary if reading from a savefile */
 504         if (pd != NULL && pcap_file(pd) == NULL) {
 505                 (void)fflush(stdout);
 506                 putc('\n', stderr);
 507                 info(1);
 508         }
 509         exit(0);
 510 }
 511
 512 void
 513 info(register int verbose)
 514 {
 515         struct pcap_stat stat;
 516
 517         if (pcap_stats(pd, &stat) < 0) {
 518                 (void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
 519                 return;
 520         }
 521         if (!verbose)
 522                 fprintf(stderr, "%s: ", program_name);
 523         (void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
 524         if (!verbose)
 525                 fputs(", ", stderr);
 526         else
 527                 putc('\n', stderr);
 528         (void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
 529         infoprint = 0;
 530 }
 531
 532 static void
 533 reverse(char *s)
 534 {
 535         int i, j, c;
 536
 537         for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
 538                 c = s[i];
 539                 s[i] = s[j];
 540                 s[j] = c;
 541         }
 542 }
 543
 544
 545 static void
 546 swebitoa(unsigned int n, char *s)
 547 {
 548         unsigned int i;
 549
 550         i = 0;
 551         do {
 552                 s[i++] = n % 10 + '0';
 553         } while ((n /= 10) > 0);
 554
 555         s[i] = '\0';
 556         reverse(s);
 557 }
 558
 559 static void
 560 dump_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 561 {
 562         struct dump_info *info;
 563         static uint cnt = 2;
 564         char *name;
 565
 566         info = (struct dump_info *)user;
 567
 568         /*
 569          * XXX - this won't prevent capture files from getting
 570          * larger than Cflag - the last packet written to the
 571          * file could put it over Cflag.
 572          */
 573         if (ftell((FILE *)info->p) > Cflag) {
 574                 name = (char *) malloc(strlen(info->WFileName) + 4);
 575                 if (name == NULL)
 576                         error("dump_and_trunc: malloc");
 577                 strcpy(name, info->WFileName);
 578                 swebitoa(cnt, name + strlen(info->WFileName));
 579                 cnt++;
 580                 pcap_dump_close(info->p);
 581                 info->p = pcap_dump_open(info->pd, name);
 582                 free(name);
 583                 if (info->p == NULL)
 584                         error("%s", pcap_geterr(pd));
 585         }
 586
 587         pcap_dump((u_char *)info->p, h, sp);
 588 }
 589
 590 /* Like default_print() but data need not be aligned */
 591 void
 592 default_print_unaligned(register const u_char *cp, register u_int length)
 593 {
 594         register u_int i, s;
 595         register int nshorts;
 596
 597         if (Xflag) {
 598                 ascii_print(cp, length);
 599                 return;
 600         }
 601         nshorts = (u_int) length / sizeof(u_short);
 602         i = 0;
 603         while (--nshorts >= 0) {
 604                 if ((i++ % 8) == 0)
 605                         (void)printf("\n\t\t\t");
 606                 s = *cp++;
 607                 (void)printf(" %02x%02x", s, *cp++);
 608         }
 609         if (length & 1) {
 610                 if ((i % 8) == 0)
 611                         (void)printf("\n\t\t\t");
 612                 (void)printf(" %02x", *cp);
 613         }
 614 }
 615
 616 /*
 617  * By default, print the packet out in hex.
 618  */
 619 void
 620 default_print(register const u_char *bp, register u_int length)
 621 {
 622         default_print_unaligned(bp, length);
 623 }
 624
 625 #ifdef SIGINFO
 626 RETSIGTYPE requestinfo(int signo)
 627 {
 628         if (infodelay)
 629                 ++infoprint;
 630         else
 631                 info(0);
 632 }
 633 #endif
 634
 635 static void
 636 usage(void)
 637 {
 638         extern char version[];
 639         extern char pcap_version[];
 640
 641         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 642         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 643         (void)fprintf(stderr,
 644 "Usage: %s [-adeflnNOpqRStuvxX] [ -c count ] [ -C file_size ]\n", program_name);
 645         (void)fprintf(stderr,
 646 "\t\t[ -F file ] [ -i interface ] [ -r file ] [ -s snaplen ]\n");
 647         (void)fprintf(stderr,
 648 "\t\t[ -T type ] [ -w file ] [ -E algo:secret ] [ expression ]\n");
 649         exit(1);
 650 }