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 1.135 1999-11-21 09:37:04 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
  54 #include <netinet/in_systm.h>
  55 #include <netinet/ip.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;                      /* print raw TCP sequence numbers */
  74 int tflag = 1;                  /* print packet arrival time */
  75 int vflag;                      /* verbose */
  76 int xflag;                      /* print packet in hex */
  77
  78 char *ahsecret = NULL;          /* AH secret key */
  79 char *espsecret = NULL;         /* ESP secret key */
  80
  81 int packettype;
  82
  83
  84 char *program_name;
  85
  86 int32_t thiszone;               /* seconds offset from gmt to local time */
  87
  88 /* Externs */
  89 extern void bpf_dump(struct bpf_program *, int);
  90
  91 /* Forwards */
  92 RETSIGTYPE cleanup(int);
  93 extern __dead void usage(void) __attribute__((volatile));
  94
  95 /* Length of saved portion of packet. */
  96 int snaplen = DEFAULT_SNAPLEN;
  97
  98 struct printer {
  99         pcap_handler f;
 100         int type;
 101 };
 102
 103 static struct printer printers[] = {
 104         { ether_if_print,       DLT_EN10MB },
 105         { ether_if_print,       DLT_IEEE802 },
 106 #ifdef DLT_LANE8023
 107         { lane_if_print,        DLT_LANE8023 },
 108 #endif
 109 #ifdef DLT_CIP
 110         { cip_if_print,         DLT_CIP },
 111 #endif
 112         { sl_if_print,          DLT_SLIP },
 113         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 114         { ppp_if_print,         DLT_PPP },
 115         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 116         { fddi_if_print,        DLT_FDDI },
 117         { null_if_print,        DLT_NULL },
 118         { raw_if_print,         DLT_RAW },
 119         { atm_if_print,         DLT_ATM_RFC1483 },
 120 #ifdef DLT_CHDLC
 121         { chdlc_if_print,       DLT_CHDLC },
 122 #endif
 123         { NULL,                 0 },
 124 };
 125
 126 static pcap_handler
 127 lookup_printer(int type)
 128 {
 129         struct printer *p;
 130
 131         for (p = printers; p->f; ++p)
 132                 if (type == p->type)
 133                         return p->f;
 134
 135         error("unknown data link type 0x%x", type);
 136         /* NOTREACHED */
 137 }
 138
 139 static pcap_t *pd;
 140
 141 extern int optind;
 142 extern int opterr;
 143 extern char *optarg;
 144
 145 int
 146 main(int argc, char **argv)
 147 {
 148         register int cnt, op, i;
 149         bpf_u_int32 localnet, netmask;
 150         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 151         pcap_handler printer;
 152         struct bpf_program fcode;
 153         RETSIGTYPE (*oldhandler)(int);
 154         u_char *pcap_userdata;
 155         char ebuf[PCAP_ERRBUF_SIZE];
 156
 157         cnt = -1;
 158         device = NULL;
 159         infile = NULL;
 160         RFileName = NULL;
 161         WFileName = NULL;
 162         if ((cp = strrchr(argv[0], '/')) != NULL)
 163                 program_name = cp + 1;
 164         else
 165                 program_name = argv[0];
 166
 167         if (abort_on_misalignment(ebuf) < 0)
 168                 error("%s", ebuf);
 169
 170         opterr = 0;
 171         while (
 172             (op = getopt(argc, argv, "ac:deE:fF:i:lnNOpqr:Rs:StT:vw:xY")) != EOF)
 173                 switch (op) {
 174
 175                 case 'a':
 176                         ++aflag;
 177                         break;
 178
 179 #if 0
 180                 case 'A':
 181 #ifndef CRYPTO
 182                         warning("crypto code not compiled in");
 183 #endif
 184                         ahsecret = optarg;
 185                         break;
 186 #endif
 187
 188                 case 'c':
 189                         cnt = atoi(optarg);
 190                         if (cnt <= 0)
 191                                 error("invalid packet count %s", optarg);
 192                         break;
 193
 194                 case 'd':
 195                         ++dflag;
 196                         break;
 197
 198                 case 'e':
 199                         ++eflag;
 200                         break;
 201
 202                 case 'E':
 203 #ifndef CRYPTO
 204                         warning("crypto code not compiled in");
 205 #endif
 206                         espsecret = optarg;
 207                         break;
 208
 209                 case 'f':
 210                         ++fflag;
 211                         break;
 212
 213                 case 'F':
 214                         infile = optarg;
 215                         break;
 216
 217                 case 'i':
 218                         device = optarg;
 219                         break;
 220
 221                 case 'l':
 222 #ifdef HAVE_SETLINEBUF
 223                         setlinebuf(stdout);
 224 #else
 225                         setvbuf(stdout, NULL, _IOLBF, 0);
 226 #endif
 227                         break;
 228
 229                 case 'n':
 230                         ++nflag;
 231                         break;
 232
 233                 case 'N':
 234                         ++Nflag;
 235                         break;
 236
 237                 case 'O':
 238                         Oflag = 0;
 239                         break;
 240
 241                 case 'p':
 242                         ++pflag;
 243                         break;
 244
 245                 case 'q':
 246                         ++qflag;
 247                         break;
 248
 249                 case 'r':
 250                         RFileName = optarg;
 251                         break;
 252
 253                 case 'R':
 254                         Rflag = 0;
 255                         break;
 256
 257                 case 's':
 258                         snaplen = atoi(optarg);
 259                         if (snaplen <= 0)
 260                                 error("invalid snaplen %s", optarg);
 261                         break;
 262
 263                 case 'S':
 264                         ++Sflag;
 265                         break;
 266
 267                 case 't':
 268                         --tflag;
 269                         break;
 270
 271                 case 'T':
 272                         if (strcasecmp(optarg, "vat") == 0)
 273                                 packettype = PT_VAT;
 274                         else if (strcasecmp(optarg, "wb") == 0)
 275                                 packettype = PT_WB;
 276                         else if (strcasecmp(optarg, "rpc") == 0)
 277                                 packettype = PT_RPC;
 278                         else if (strcasecmp(optarg, "rtp") == 0)
 279                                 packettype = PT_RTP;
 280                         else if (strcasecmp(optarg, "rtcp") == 0)
 281                                 packettype = PT_RTCP;
 282                         else if (strcasecmp(optarg, "snmp") == 0)
 283                                 packettype = PT_SNMP;
 284                         else
 285                                 error("unknown packet type `%s'", optarg);
 286                         break;
 287
 288                 case 'v':
 289                         ++vflag;
 290                         break;
 291
 292                 case 'w':
 293                         WFileName = optarg;
 294                         break;
 295 #ifdef YYDEBUG
 296                 case 'Y':
 297                         {
 298                         /* Undocumented flag */
 299                         extern int yydebug;
 300                         yydebug = 1;
 301                         }
 302                         break;
 303 #endif
 304                 case 'x':
 305                         ++xflag;
 306                         break;
 307
 308                 default:
 309                         usage();
 310                         /* NOTREACHED */
 311                 }
 312
 313         if (aflag && nflag)
 314                 error("-a and -n options are incompatible");
 315
 316         if (tflag > 0)
 317                 thiszone = gmt2local(0);
 318
 319         if (RFileName != NULL) {
 320                 /*
 321                  * We don't need network access, so set it back to the user id.
 322                  * Also, this prevents the user from reading anyone's
 323                  * trace file.
 324                  */
 325                 setuid(getuid());
 326
 327                 pd = pcap_open_offline(RFileName, ebuf);
 328                 if (pd == NULL)
 329                         error("%s", ebuf);
 330                 localnet = 0;
 331                 netmask = 0;
 332                 if (fflag != 0)
 333                         error("-f and -r options are incompatible");
 334         } else {
 335                 if (device == NULL) {
 336                         device = pcap_lookupdev(ebuf);
 337                         if (device == NULL)
 338                                 error("%s", ebuf);
 339                 }
 340                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 341                 if (pd == NULL)
 342                         error("%s", ebuf);
 343                 i = pcap_snapshot(pd);
 344                 if (snaplen < i) {
 345                         warning("snaplen raised from %d to %d", snaplen, i);
 346                         snaplen = i;
 347                 }
 348                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 349                         localnet = 0;
 350                         netmask = 0;
 351                         warning("%s", ebuf);
 352                 }
 353                 /*
 354                  * Let user own process after socket has been opened.
 355                  */
 356                 setuid(getuid());
 357         }
 358         if (infile)
 359                 cmdbuf = read_infile(infile);
 360         else
 361                 cmdbuf = copy_argv(&argv[optind]);
 362
 363         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 364                 error("%s", pcap_geterr(pd));
 365         if (dflag) {
 366                 bpf_dump(&fcode, dflag);
 367                 exit(0);
 368         }
 369         init_addrtoname(localnet, netmask);
 370
 371         (void)setsignal(SIGTERM, cleanup);
 372         (void)setsignal(SIGINT, cleanup);
 373         /* Cooperate with nohup(1) */
 374         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 375                 (void)setsignal(SIGHUP, oldhandler);
 376
 377         if (pcap_setfilter(pd, &fcode) < 0)
 378                 error("%s", pcap_geterr(pd));
 379         if (WFileName) {
 380                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 381                 if (p == NULL)
 382                         error("%s", pcap_geterr(pd));
 383                 printer = pcap_dump;
 384                 pcap_userdata = (u_char *)p;
 385         } else {
 386                 printer = lookup_printer(pcap_datalink(pd));
 387                 pcap_userdata = 0;
 388         }
 389         if (RFileName == NULL) {
 390                 (void)fprintf(stderr, "%s: listening on %s\n",
 391                     program_name, device);
 392                 (void)fflush(stderr);
 393         }
 394         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 395                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 396                     program_name, pcap_geterr(pd));
 397                 exit(1);
 398         }
 399         pcap_close(pd);
 400         exit(0);
 401 }
 402
 403 /* make a clean exit on interrupts */
 404 RETSIGTYPE
 405 cleanup(int signo)
 406 {
 407         struct pcap_stat stat;
 408
 409         /* Can't print the summary if reading from a savefile */
 410         if (pd != NULL && pcap_file(pd) == NULL) {
 411                 (void)fflush(stdout);
 412                 putc('\n', stderr);
 413                 if (pcap_stats(pd, &stat) < 0)
 414                         (void)fprintf(stderr, "pcap_stats: %s\n",
 415                             pcap_geterr(pd));
 416                 else {
 417                         (void)fprintf(stderr, "%d packets received by filter\n",
 418                             stat.ps_recv);
 419                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 420                             stat.ps_drop);
 421                 }
 422         }
 423         exit(0);
 424 }
 425
 426 /* Like default_print() but data need not be aligned */
 427 void
 428 default_print_unaligned(register const u_char *cp, register u_int length)
 429 {
 430   register u_int i, s;
 431   register int nshorts;
 432
 433   char line[81];
 434
 435   nshorts = (u_int) length / sizeof(u_short);
 436   i = 0;
 437   memset(line, ' ', 80);
 438   line[81]='\0';
 439
 440   putchar('\n');
 441   while (nshorts >= 0) {
 442
 443     sprintf(line+20+i*5, "%02x%02x  ", cp[0], cp[1]);
 444
 445     if(isprint(cp[0])) {
 446       line[62+i*2]=cp[0];
 447     } else {
 448       line[62+i*2]='.';
 449     }
 450     if(isprint(cp[1])) {
 451       line[62+i*2+1]=cp[1];
 452     } else {
 453       line[62+i*2+1]='.';
 454     }
 455     i++;
 456     if (i == 8) {
 457       line[60]=' ';
 458       line[61]=' ';
 459       line[62+16]='\0';
 460       puts(line);
 461       i=0;
 462     }
 463     cp += 2;
 464     nshorts--;
 465   }
 466 }
 467
 468 /*
 469  * By default, print the packet out in hex.
 470  *
 471  * (BTW, please don't send us patches to print the packet out in ascii)
 472  */
 473 void
 474 default_print(register const u_char *bp, register u_int length)
 475 {
 476         register const u_short *sp;
 477         register u_int i;
 478         register int nshorts;
 479
 480         default_print_unaligned(bp, length);
 481 }
 482
 483 __dead void
 484 usage(void)
 485 {
 486         extern char version[];
 487         extern char pcap_version[];
 488
 489         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 490         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 491         (void)fprintf(stderr,
 492 "Usage: %s [-adeflnNOpqStvx] [-c count] [ -F file ]\n", program_name);
 493         (void)fprintf(stderr,
 494 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 495         (void)fprintf(stderr,
 496 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 497         exit(-1);
 498 }