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 1.175 2002-04-24 06:55:56 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 int Aflag = 0;                  /* print packet only in ascii observing LF, CR, TAB, SPACE */
  87
  88 char *espsecret = NULL;         /* ESP secret key */
  89
  90 int packettype;
  91
  92 int infodelay;
  93 int infoprint;
  94
  95 char *program_name;
  96
  97 int32_t thiszone;               /* seconds offset from gmt to local time */
  98
  99 /* Forwards */
 100 static RETSIGTYPE cleanup(int);
 101 static void usage(void) __attribute__((noreturn));
 102
 103 static void dump_and_trunc(u_char *, const struct pcap_pkthdr *, const u_char *);
 104
 105 #ifdef SIGINFO
 106 RETSIGTYPE requestinfo(int);
 107 #endif
 108
 109 /* Length of saved portion of packet. */
 110 int snaplen = DEFAULT_SNAPLEN;
 111
 112 struct printer {
 113         pcap_handler f;
 114         int type;
 115 };
 116
 117 static struct printer printers[] = {
 118         { arcnet_if_print,      DLT_ARCNET },
 119         { ether_if_print,       DLT_EN10MB },
 120         { token_if_print,       DLT_IEEE802 },
 121 #ifdef DLT_LANE8023
 122         { lane_if_print,        DLT_LANE8023 },
 123 #endif
 124 #ifdef DLT_CIP
 125         { cip_if_print,         DLT_CIP },
 126 #endif
 127 #ifdef DLT_ATM_CLIP
 128         { cip_if_print,         DLT_ATM_CLIP },
 129 #endif
 130         { sl_if_print,          DLT_SLIP },
 131         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 132         { ppp_if_print,         DLT_PPP },
 133         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 134         { fddi_if_print,        DLT_FDDI },
 135         { null_if_print,        DLT_NULL },
 136 #ifdef DLT_LOOP
 137         { null_if_print,        DLT_LOOP },
 138 #endif
 139         { raw_if_print,         DLT_RAW },
 140         { atm_if_print,         DLT_ATM_RFC1483 },
 141 #ifdef DLT_C_HDLC
 142         { chdlc_if_print,       DLT_C_HDLC },
 143 #endif
 144 #ifdef DLT_HDLC
 145         { chdlc_if_print,       DLT_HDLC },
 146 #endif
 147 #ifdef DLT_PPP_SERIAL
 148         { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 149 #endif
 150 #ifdef DLT_PPP_ETHER
 151         { pppoe_if_print,       DLT_PPP_ETHER },
 152 #endif
 153 #ifdef DLT_LINUX_SLL
 154         { sll_if_print,         DLT_LINUX_SLL },
 155 #endif
 156 #ifdef DLT_IEEE802_11
 157         { ieee802_11_if_print,  DLT_IEEE802_11},
 158 #endif
 159 #ifdef DLT_LTALK
 160         { ltalk_if_print,       DLT_LTALK },
 161 #endif
 162 #ifdef DLT_PFLOG
 163         { pflog_if_print,       DLT_PFLOG },
 164 #endif
 165         { NULL,                 0 },
 166 };
 167
 168 static pcap_handler
 169 lookup_printer(int type)
 170 {
 171         struct printer *p;
 172
 173         for (p = printers; p->f; ++p)
 174                 if (type == p->type)
 175                         return p->f;
 176
 177         error("unknown data link type %d", type);
 178         /* NOTREACHED */
 179 }
 180
 181 static pcap_t *pd;
 182
 183 extern int optind;
 184 extern int opterr;
 185 extern char *optarg;
 186
 187 struct dump_info {
 188         char    *WFileName;
 189         pcap_t  *pd;
 190         pcap_dumper_t *p;
 191 };
 192
 193 int
 194 main(int argc, char **argv)
 195 {
 196         register int cnt, op, i;
 197         bpf_u_int32 localnet, netmask;
 198         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 199         pcap_handler printer;
 200         struct bpf_program fcode;
 201         RETSIGTYPE (*oldhandler)(int);
 202         struct dump_info dumpinfo;
 203         u_char *pcap_userdata;
 204         char ebuf[PCAP_ERRBUF_SIZE];
 205
 206         cnt = -1;
 207         device = NULL;
 208         infile = NULL;
 209         RFileName = NULL;
 210         WFileName = NULL;
 211         if ((cp = strrchr(argv[0], '/')) != NULL)
 212                 program_name = cp + 1;
 213         else
 214                 program_name = argv[0];
 215
 216         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 217                 error("%s", ebuf);
 218
 219 #ifdef LIBSMI
 220         smiInit("tcpdump");
 221 #endif
 222
 223         opterr = 0;
 224         while (
 225             (op = getopt(argc, argv, "aAc:C:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 226                 switch (op) {
 227
 228                 case 'a':
 229                         ++aflag;
 230                         break;
 231
 232                case 'A':
 233                        ++xflag;
 234                        ++Xflag;
 235                        ++Aflag;
 236                        break;
 237
 238                 case 'c':
 239                         cnt = atoi(optarg);
 240                         if (cnt <= 0)
 241                                 error("invalid packet count %s", optarg);
 242                         break;
 243
 244                 case 'C':
 245                         Cflag = atoi(optarg) * 1000000;
 246                         if (Cflag < 0)
 247                                 error("invalid file size %s", optarg);
 248                         break;
 249
 250                 case 'd':
 251                         ++dflag;
 252                         break;
 253
 254                 case 'e':
 255                         ++eflag;
 256                         break;
 257
 258                 case 'E':
 259 #ifndef HAVE_LIBCRYPTO
 260                         warning("crypto code not compiled in");
 261 #endif
 262                         espsecret = optarg;
 263                         break;
 264
 265                 case 'f':
 266                         ++fflag;
 267                         break;
 268
 269                 case 'F':
 270                         infile = optarg;
 271                         break;
 272
 273                 case 'i':
 274                         device = optarg;
 275                         break;
 276
 277                 case 'l':
 278 #ifdef HAVE_SETLINEBUF
 279                         setlinebuf(stdout);
 280 #else
 281                         setvbuf(stdout, NULL, _IOLBF, 0);
 282 #endif
 283                         break;
 284
 285                 case 'n':
 286                         ++nflag;
 287                         break;
 288
 289                 case 'N':
 290                         ++Nflag;
 291                         break;
 292
 293                 case 'm':
 294 #ifdef LIBSMI
 295                         if (smiLoadModule(optarg) == 0) {
 296                                 error("could not load MIB module %s", optarg);
 297                         }
 298                         sflag = 1;
 299 #else
 300                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 301                                       program_name, optarg);
 302                         (void)fprintf(stderr, "(no libsmi support)\n");
 303 #endif
 304
 305                 case 'O':
 306                         Oflag = 0;
 307                         break;
 308
 309                 case 'p':
 310                         ++pflag;
 311                         break;
 312
 313                 case 'q':
 314                         ++qflag;
 315                         break;
 316
 317                 case 'r':
 318                         RFileName = optarg;
 319                         break;
 320
 321                 case 'R':
 322                         Rflag = 0;
 323                         break;
 324
 325                 case 's': {
 326                         char *end;
 327
 328                         snaplen = strtol(optarg, &end, 0);
 329                         if (optarg == end || *end != '\0'
 330                             || snaplen < 0 || snaplen > 65535)
 331                                 error("invalid snaplen %s", optarg);
 332                         else if (snaplen == 0)
 333                                 snaplen = 65535;
 334                         break;
 335                 }
 336
 337                 case 'S':
 338                         ++Sflag;
 339                         break;
 340
 341                 case 't':
 342                         --tflag;
 343                         break;
 344
 345                 case 'T':
 346                         if (strcasecmp(optarg, "vat") == 0)
 347                                 packettype = PT_VAT;
 348                         else if (strcasecmp(optarg, "wb") == 0)
 349                                 packettype = PT_WB;
 350                         else if (strcasecmp(optarg, "rpc") == 0)
 351                                 packettype = PT_RPC;
 352                         else if (strcasecmp(optarg, "rtp") == 0)
 353                                 packettype = PT_RTP;
 354                         else if (strcasecmp(optarg, "rtcp") == 0)
 355                                 packettype = PT_RTCP;
 356                         else if (strcasecmp(optarg, "snmp") == 0)
 357                                 packettype = PT_SNMP;
 358                         else if (strcasecmp(optarg, "cnfp") == 0)
 359                                 packettype = PT_CNFP;
 360                         else
 361                                 error("unknown packet type `%s'", optarg);
 362                         break;
 363
 364                 case 'u':
 365                         ++uflag;
 366                         break;
 367
 368                 case 'v':
 369                         ++vflag;
 370                         break;
 371
 372                 case 'w':
 373                         WFileName = optarg;
 374                         break;
 375
 376                 case 'x':
 377                         ++xflag;
 378                         break;
 379
 380                 case 'X':
 381                         ++xflag;
 382                         ++Xflag;
 383                         break;
 384
 385 #ifdef YYDEBUG
 386                 case 'Y':
 387                         {
 388                         /* Undocumented flag */
 389                         extern int yydebug;
 390                         yydebug = 1;
 391                         }
 392                         break;
 393 #endif
 394                 default:
 395                         usage();
 396                         /* NOTREACHED */
 397                 }
 398
 399         if (aflag && nflag)
 400                 error("-a and -n options are incompatible");
 401
 402         if (tflag > 0)
 403                 thiszone = gmt2local(0);
 404
 405         if (RFileName != NULL) {
 406                 /*
 407                  * We don't need network access, so set it back to the user id.
 408                  * Also, this prevents the user from reading anyone's
 409                  * trace file.
 410                  */
 411                 setuid(getuid());
 412
 413                 pd = pcap_open_offline(RFileName, ebuf);
 414                 if (pd == NULL)
 415                         error("%s", ebuf);
 416                 localnet = 0;
 417                 netmask = 0;
 418                 if (fflag != 0)
 419                         error("-f and -r options are incompatible");
 420         } else {
 421                 if (device == NULL) {
 422                         device = pcap_lookupdev(ebuf);
 423                         if (device == NULL)
 424                                 error("%s", ebuf);
 425                 }
 426                 *ebuf = '\0';
 427                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 428                 if (pd == NULL)
 429                         error("%s", ebuf);
 430                 else if (*ebuf)
 431                         warning("%s", ebuf);
 432                 i = pcap_snapshot(pd);
 433                 if (snaplen < i) {
 434                         warning("snaplen raised from %d to %d", snaplen, i);
 435                         snaplen = i;
 436                 }
 437                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 438                         localnet = 0;
 439                         netmask = 0;
 440                         warning("%s", ebuf);
 441                 }
 442                 /*
 443                  * Let user own process after socket has been opened.
 444                  */
 445                 setuid(getuid());
 446         }
 447         if (infile)
 448                 cmdbuf = read_infile(infile);
 449         else
 450                 cmdbuf = copy_argv(&argv[optind]);
 451
 452         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 453                 error("%s", pcap_geterr(pd));
 454         if (dflag) {
 455                 bpf_dump(&fcode, dflag);
 456                 exit(0);
 457         }
 458         init_addrtoname(localnet, netmask);
 459
 460         (void)setsignal(SIGTERM, cleanup);
 461         (void)setsignal(SIGINT, cleanup);
 462         /* Cooperate with nohup(1) */
 463         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 464                 (void)setsignal(SIGHUP, oldhandler);
 465
 466         if (pcap_setfilter(pd, &fcode) < 0)
 467                 error("%s", pcap_geterr(pd));
 468         if (WFileName) {
 469                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 470                 if (p == NULL)
 471                         error("%s", pcap_geterr(pd));
 472                 if (Cflag != 0) {
 473                         printer = dump_and_trunc;
 474                         dumpinfo.WFileName = WFileName;
 475                         dumpinfo.pd = pd;
 476                         dumpinfo.p = p;
 477                         pcap_userdata = (u_char *)&dumpinfo;
 478                 } else {
 479                         printer = pcap_dump;
 480                         pcap_userdata = (u_char *)p;
 481                 }
 482         } else {
 483                 printer = lookup_printer(pcap_datalink(pd));
 484                 pcap_userdata = 0;
 485 #ifdef SIGINFO
 486                 (void)setsignal(SIGINFO, requestinfo);
 487 #endif
 488         }
 489         if (RFileName == NULL) {
 490                 (void)fprintf(stderr, "%s: listening on %s\n",
 491                     program_name, device);
 492                 (void)fflush(stderr);
 493         }
 494         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 495                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 496                     program_name, pcap_geterr(pd));
 497                 exit(1);
 498         }
 499         if (RFileName == NULL)
 500                 info(1);
 501         pcap_close(pd);
 502         exit(0);
 503 }
 504
 505 /* make a clean exit on interrupts */
 506 static RETSIGTYPE
 507 cleanup(int signo)
 508 {
 509
 510         /* Can't print the summary if reading from a savefile */
 511         if (pd != NULL && pcap_file(pd) == NULL) {
 512                 (void)fflush(stdout);
 513                 putc('\n', stderr);
 514                 info(1);
 515         }
 516         exit(0);
 517 }
 518
 519 void
 520 info(register int verbose)
 521 {
 522         struct pcap_stat stat;
 523
 524         if (pcap_stats(pd, &stat) < 0) {
 525                 (void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
 526                 return;
 527         }
 528         if (!verbose)
 529                 fprintf(stderr, "%s: ", program_name);
 530         (void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
 531         if (!verbose)
 532                 fputs(", ", stderr);
 533         else
 534                 putc('\n', stderr);
 535         (void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
 536         infoprint = 0;
 537 }
 538
 539 static void
 540 reverse(char *s)
 541 {
 542         int i, j, c;
 543
 544         for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
 545                 c = s[i];
 546                 s[i] = s[j];
 547                 s[j] = c;
 548         }
 549 }
 550
 551
 552 static void
 553 swebitoa(unsigned int n, char *s)
 554 {
 555         unsigned int i;
 556
 557         i = 0;
 558         do {
 559                 s[i++] = n % 10 + '0';
 560         } while ((n /= 10) > 0);
 561
 562         s[i] = '\0';
 563         reverse(s);
 564 }
 565
 566 static void
 567 dump_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 568 {
 569         struct dump_info *info;
 570         static uint cnt = 2;
 571         char *name;
 572
 573         info = (struct dump_info *)user;
 574
 575         /*
 576          * XXX - this won't prevent capture files from getting
 577          * larger than Cflag - the last packet written to the
 578          * file could put it over Cflag.
 579          */
 580         if (ftell((FILE *)info->p) > Cflag) {
 581                 name = (char *) malloc(strlen(info->WFileName) + 4);
 582                 if (name == NULL)
 583                         error("dump_and_trunc: malloc");
 584                 strcpy(name, info->WFileName);
 585                 swebitoa(cnt, name + strlen(info->WFileName));
 586                 cnt++;
 587                 pcap_dump_close(info->p);
 588                 info->p = pcap_dump_open(info->pd, name);
 589                 free(name);
 590                 if (info->p == NULL)
 591                         error("%s", pcap_geterr(pd));
 592         }
 593
 594         pcap_dump((u_char *)info->p, h, sp);
 595 }
 596
 597 /* Like default_print() but data need not be aligned */
 598 void
 599 default_print_unaligned(register const u_char *cp, register u_int length)
 600 {
 601         register u_int i, s;
 602         register int nshorts;
 603
 604         if (Xflag) {
 605                 ascii_print(cp, length);
 606                 return;
 607         }
 608         nshorts = (u_int) length / sizeof(u_short);
 609         i = 0;
 610         while (--nshorts >= 0) {
 611                 if ((i++ % 8) == 0)
 612                         (void)printf("\n\t\t\t");
 613                 s = *cp++;
 614                 (void)printf(" %02x%02x", s, *cp++);
 615         }
 616         if (length & 1) {
 617                 if ((i % 8) == 0)
 618                         (void)printf("\n\t\t\t");
 619                 (void)printf(" %02x", *cp);
 620         }
 621 }
 622
 623 /*
 624  * By default, print the packet out in hex.
 625  */
 626 void
 627 default_print(register const u_char *bp, register u_int length)
 628 {
 629         default_print_unaligned(bp, length);
 630 }
 631
 632 #ifdef SIGINFO
 633 RETSIGTYPE requestinfo(int signo)
 634 {
 635         if (infodelay)
 636                 ++infoprint;
 637         else
 638                 info(0);
 639 }
 640 #endif
 641
 642 static void
 643 usage(void)
 644 {
 645         extern char version[];
 646         extern char pcap_version[];
 647
 648         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 649         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 650         (void)fprintf(stderr,
 651 "Usage: %s [-aAdeflnNOpqRStuvxX] [ -c count ] [ -C file_size ]\n", program_name);
 652         (void)fprintf(stderr,
 653 "\t\t[ -F file ] [ -i interface ] [ -r file ] [ -s snaplen ]\n");
 654         (void)fprintf(stderr,
 655 "\t\t[ -T type ] [ -w file ] [ -E algo:secret ] [ expression ]\n");
 656         exit(1);
 657 }