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 1.179 2002-07-11 09:17:25 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 #ifdef DLT_FR
 166         { fr_if_print,          DLT_FR },
 167 #endif
 168 #ifdef DLT_FRELAY
 169         { fr_if_print,          DLT_FRELAY },
 170 #endif
 171 #ifdef DLT_SUNATM
 172         { sunatm_if_print,      DLT_SUNATM },
 173 #endif
 174         { NULL,                 0 },
 175 };
 176
 177 static pcap_handler
 178 lookup_printer(int type)
 179 {
 180         struct printer *p;
 181
 182         for (p = printers; p->f; ++p)
 183                 if (type == p->type)
 184                         return p->f;
 185
 186         error("unknown data link type %d", type);
 187         /* NOTREACHED */
 188 }
 189
 190 static pcap_t *pd;
 191
 192 extern int optind;
 193 extern int opterr;
 194 extern char *optarg;
 195
 196 struct dump_info {
 197         char    *WFileName;
 198         pcap_t  *pd;
 199         pcap_dumper_t *p;
 200 };
 201
 202 int
 203 main(int argc, char **argv)
 204 {
 205         register int cnt, op, i;
 206         bpf_u_int32 localnet, netmask;
 207         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 208         pcap_handler printer;
 209         struct bpf_program fcode;
 210         RETSIGTYPE (*oldhandler)(int);
 211         struct dump_info dumpinfo;
 212         u_char *pcap_userdata;
 213         char ebuf[PCAP_ERRBUF_SIZE];
 214
 215         cnt = -1;
 216         device = NULL;
 217         infile = NULL;
 218         RFileName = NULL;
 219         WFileName = NULL;
 220         if ((cp = strrchr(argv[0], '/')) != NULL)
 221                 program_name = cp + 1;
 222         else
 223                 program_name = argv[0];
 224
 225         if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 226                 error("%s", ebuf);
 227
 228 #ifdef LIBSMI
 229         smiInit("tcpdump");
 230 #endif
 231
 232         opterr = 0;
 233         while (
 234             (op = getopt(argc, argv, "aAc:C:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
 235                 switch (op) {
 236
 237                 case 'a':
 238                         ++aflag;
 239                         break;
 240
 241                case 'A':
 242                        ++xflag;
 243                        ++Xflag;
 244                        ++Aflag;
 245                        break;
 246
 247                 case 'c':
 248                         cnt = atoi(optarg);
 249                         if (cnt <= 0)
 250                                 error("invalid packet count %s", optarg);
 251                         break;
 252
 253                 case 'C':
 254                         Cflag = atoi(optarg) * 1000000;
 255                         if (Cflag < 0)
 256                                 error("invalid file size %s", optarg);
 257                         break;
 258
 259                 case 'd':
 260                         ++dflag;
 261                         break;
 262
 263                 case 'e':
 264                         ++eflag;
 265                         break;
 266
 267                 case 'E':
 268 #ifndef HAVE_LIBCRYPTO
 269                         warning("crypto code not compiled in");
 270 #endif
 271                         espsecret = optarg;
 272                         break;
 273
 274                 case 'f':
 275                         ++fflag;
 276                         break;
 277
 278                 case 'F':
 279                         infile = optarg;
 280                         break;
 281
 282                 case 'i':
 283                         device = optarg;
 284                         break;
 285
 286                 case 'l':
 287 #ifdef HAVE_SETLINEBUF
 288                         setlinebuf(stdout);
 289 #else
 290                         setvbuf(stdout, NULL, _IOLBF, 0);
 291 #endif
 292                         break;
 293
 294                 case 'n':
 295                         ++nflag;
 296                         break;
 297
 298                 case 'N':
 299                         ++Nflag;
 300                         break;
 301
 302                 case 'm':
 303 #ifdef LIBSMI
 304                         if (smiLoadModule(optarg) == 0) {
 305                                 error("could not load MIB module %s", optarg);
 306                         }
 307                         sflag = 1;
 308 #else
 309                         (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
 310                                       program_name, optarg);
 311                         (void)fprintf(stderr, "(no libsmi support)\n");
 312 #endif
 313
 314                 case 'O':
 315                         Oflag = 0;
 316                         break;
 317
 318                 case 'p':
 319                         ++pflag;
 320                         break;
 321
 322                 case 'q':
 323                         ++qflag;
 324                         break;
 325
 326                 case 'r':
 327                         RFileName = optarg;
 328                         break;
 329
 330                 case 'R':
 331                         Rflag = 0;
 332                         break;
 333
 334                 case 's': {
 335                         char *end;
 336
 337                         snaplen = strtol(optarg, &end, 0);
 338                         if (optarg == end || *end != '\0'
 339                             || snaplen < 0 || snaplen > 65535)
 340                                 error("invalid snaplen %s", optarg);
 341                         else if (snaplen == 0)
 342                                 snaplen = 65535;
 343                         break;
 344                 }
 345
 346                 case 'S':
 347                         ++Sflag;
 348                         break;
 349
 350                 case 't':
 351                         --tflag;
 352                         break;
 353
 354                 case 'T':
 355                         if (strcasecmp(optarg, "vat") == 0)
 356                                 packettype = PT_VAT;
 357                         else if (strcasecmp(optarg, "wb") == 0)
 358                                 packettype = PT_WB;
 359                         else if (strcasecmp(optarg, "rpc") == 0)
 360                                 packettype = PT_RPC;
 361                         else if (strcasecmp(optarg, "rtp") == 0)
 362                                 packettype = PT_RTP;
 363                         else if (strcasecmp(optarg, "rtcp") == 0)
 364                                 packettype = PT_RTCP;
 365                         else if (strcasecmp(optarg, "snmp") == 0)
 366                                 packettype = PT_SNMP;
 367                         else if (strcasecmp(optarg, "cnfp") == 0)
 368                                 packettype = PT_CNFP;
 369                         else
 370                                 error("unknown packet type `%s'", optarg);
 371                         break;
 372
 373                 case 'u':
 374                         ++uflag;
 375                         break;
 376
 377                 case 'v':
 378                         ++vflag;
 379                         break;
 380
 381                 case 'w':
 382                         WFileName = optarg;
 383                         break;
 384
 385                 case 'x':
 386                         ++xflag;
 387                         break;
 388
 389                 case 'X':
 390                         ++xflag;
 391                         ++Xflag;
 392                         break;
 393
 394 #ifdef YYDEBUG
 395                 case 'Y':
 396                         {
 397                         /* Undocumented flag */
 398                         extern int yydebug;
 399                         yydebug = 1;
 400                         }
 401                         break;
 402 #endif
 403                 default:
 404                         usage();
 405                         /* NOTREACHED */
 406                 }
 407
 408         if (aflag && nflag)
 409                 error("-a and -n options are incompatible");
 410
 411         if (tflag > 0)
 412                 thiszone = gmt2local(0);
 413
 414         if (RFileName != NULL) {
 415                 /*
 416                  * We don't need network access, so set it back to the user id.
 417                  * Also, this prevents the user from reading anyone's
 418                  * trace file.
 419                  */
 420                 setuid(getuid());
 421
 422                 pd = pcap_open_offline(RFileName, ebuf);
 423                 if (pd == NULL)
 424                         error("%s", ebuf);
 425                 localnet = 0;
 426                 netmask = 0;
 427                 if (fflag != 0)
 428                         error("-f and -r options are incompatible");
 429         } else {
 430                 if (device == NULL) {
 431                         device = pcap_lookupdev(ebuf);
 432                         if (device == NULL)
 433                                 error("%s", ebuf);
 434                 }
 435                 *ebuf = '\0';
 436                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 437                 if (pd == NULL)
 438                         error("%s", ebuf);
 439                 else if (*ebuf)
 440                         warning("%s", ebuf);
 441                 i = pcap_snapshot(pd);
 442                 if (snaplen < i) {
 443                         warning("snaplen raised from %d to %d", snaplen, i);
 444                         snaplen = i;
 445                 }
 446                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 447                         localnet = 0;
 448                         netmask = 0;
 449                         warning("%s", ebuf);
 450                 }
 451                 /*
 452                  * Let user own process after socket has been opened.
 453                  */
 454                 setuid(getuid());
 455         }
 456         if (infile)
 457                 cmdbuf = read_infile(infile);
 458         else
 459                 cmdbuf = copy_argv(&argv[optind]);
 460
 461         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 462                 error("%s", pcap_geterr(pd));
 463         if (dflag) {
 464                 bpf_dump(&fcode, dflag);
 465                 exit(0);
 466         }
 467         init_addrtoname(localnet, netmask);
 468
 469         (void)setsignal(SIGTERM, cleanup);
 470         (void)setsignal(SIGINT, cleanup);
 471         /* Cooperate with nohup(1) */
 472         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 473                 (void)setsignal(SIGHUP, oldhandler);
 474
 475         if (pcap_setfilter(pd, &fcode) < 0)
 476                 error("%s", pcap_geterr(pd));
 477         if (WFileName) {
 478                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 479                 if (p == NULL)
 480                         error("%s", pcap_geterr(pd));
 481                 if (Cflag != 0) {
 482                         printer = dump_and_trunc;
 483                         dumpinfo.WFileName = WFileName;
 484                         dumpinfo.pd = pd;
 485                         dumpinfo.p = p;
 486                         pcap_userdata = (u_char *)&dumpinfo;
 487                 } else {
 488                         printer = pcap_dump;
 489                         pcap_userdata = (u_char *)p;
 490                 }
 491         } else {
 492                 printer = lookup_printer(pcap_datalink(pd));
 493                 pcap_userdata = 0;
 494 #ifdef SIGINFO
 495                 (void)setsignal(SIGINFO, requestinfo);
 496 #endif
 497         }
 498         if (RFileName == NULL) {
 499                 (void)fprintf(stderr, "%s: listening on %s\n",
 500                     program_name, device);
 501                 (void)fflush(stderr);
 502         }
 503         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 504                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 505                     program_name, pcap_geterr(pd));
 506                 cleanup(0);
 507                 pcap_close(pd);
 508                 exit(1);
 509         }
 510         if (RFileName == NULL)
 511                 info(1);
 512         pcap_close(pd);
 513         exit(0);
 514 }
 515
 516 /* make a clean exit on interrupts */
 517 static RETSIGTYPE
 518 cleanup(int signo)
 519 {
 520
 521         /* Can't print the summary if reading from a savefile */
 522         if (pd != NULL && pcap_file(pd) == NULL) {
 523                 (void)fflush(stdout);
 524                 putc('\n', stderr);
 525                 info(1);
 526         }
 527         if (signo)
 528                 exit(0);
 529 }
 530
 531 void
 532 info(register int verbose)
 533 {
 534         struct pcap_stat stat;
 535
 536         if (pcap_stats(pd, &stat) < 0) {
 537                 (void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
 538                 return;
 539         }
 540         if (!verbose)
 541                 fprintf(stderr, "%s: ", program_name);
 542         (void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
 543         if (!verbose)
 544                 fputs(", ", stderr);
 545         else
 546                 putc('\n', stderr);
 547         (void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
 548         infoprint = 0;
 549 }
 550
 551 static void
 552 reverse(char *s)
 553 {
 554         int i, j, c;
 555
 556         for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
 557                 c = s[i];
 558                 s[i] = s[j];
 559                 s[j] = c;
 560         }
 561 }
 562
 563
 564 static void
 565 swebitoa(unsigned int n, char *s)
 566 {
 567         unsigned int i;
 568
 569         i = 0;
 570         do {
 571                 s[i++] = n % 10 + '0';
 572         } while ((n /= 10) > 0);
 573
 574         s[i] = '\0';
 575         reverse(s);
 576 }
 577
 578 static void
 579 dump_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 580 {
 581         struct dump_info *info;
 582         static uint cnt = 2;
 583         char *name;
 584
 585         info = (struct dump_info *)user;
 586
 587         /*
 588          * XXX - this won't prevent capture files from getting
 589          * larger than Cflag - the last packet written to the
 590          * file could put it over Cflag.
 591          */
 592         if (ftell((FILE *)info->p) > Cflag) {
 593                 name = (char *) malloc(strlen(info->WFileName) + 4);
 594                 if (name == NULL)
 595                         error("dump_and_trunc: malloc");
 596                 strcpy(name, info->WFileName);
 597                 swebitoa(cnt, name + strlen(info->WFileName));
 598                 cnt++;
 599                 pcap_dump_close(info->p);
 600                 info->p = pcap_dump_open(info->pd, name);
 601                 free(name);
 602                 if (info->p == NULL)
 603                         error("%s", pcap_geterr(pd));
 604         }
 605
 606         pcap_dump((u_char *)info->p, h, sp);
 607 }
 608
 609 /* Like default_print() but data need not be aligned */
 610 void
 611 default_print_unaligned(register const u_char *cp, register u_int length)
 612 {
 613         register u_int i, s;
 614         register int nshorts;
 615
 616         if (Xflag) {
 617                 ascii_print(cp, length);
 618                 return;
 619         }
 620         nshorts = (u_int) length / sizeof(u_short);
 621         i = 0;
 622         while (--nshorts >= 0) {
 623                 if ((i++ % 8) == 0)
 624                         (void)printf("\n\t\t\t");
 625                 s = *cp++;
 626                 (void)printf(" %02x%02x", s, *cp++);
 627         }
 628         if (length & 1) {
 629                 if ((i % 8) == 0)
 630                         (void)printf("\n\t\t\t");
 631                 (void)printf(" %02x", *cp);
 632         }
 633 }
 634
 635 /*
 636  * By default, print the packet out in hex.
 637  */
 638 void
 639 default_print(register const u_char *bp, register u_int length)
 640 {
 641         default_print_unaligned(bp, length);
 642 }
 643
 644 #ifdef SIGINFO
 645 RETSIGTYPE requestinfo(int signo)
 646 {
 647         if (infodelay)
 648                 ++infoprint;
 649         else
 650                 info(0);
 651 }
 652 #endif
 653
 654 static void
 655 usage(void)
 656 {
 657         extern char version[];
 658         extern char pcap_version[];
 659
 660         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 661         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 662         (void)fprintf(stderr,
 663 "Usage: %s [-aAdeflnNOpqRStuvxX] [ -c count ] [ -C file_size ]\n", program_name);
 664         (void)fprintf(stderr,
 665 "\t\t[ -F file ] [ -i interface ] [ -r file ] [ -s snaplen ]\n");
 666         (void)fprintf(stderr,
 667 "\t\t[ -T type ] [ -w file ] [ -E algo:secret ] [ expression ]\n");
 668         exit(1);
 669 }