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 1.132 1999-10-30 05:11:23 itojun 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 #include <sys/types.h>
  39 #include <sys/time.h>
  40
  41 #include <netinet/in.h>
  42
  43 #include <pcap.h>
  44 #include <signal.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49
  50 #include <netinet/in_systm.h>
  51 #include <netinet/ip.h>
  52
  53 #include "interface.h"
  54 #include "addrtoname.h"
  55 #include "machdep.h"
  56 #include "setsignal.h"
  57 #include "gmt2local.h"
  58
  59 int aflag;                      /* translate network and broadcast addresses */
  60 int dflag;                      /* print filter code */
  61 int eflag;                      /* print ethernet header */
  62 int fflag;                      /* don't translate "foreign" IP address */
  63 int nflag;                      /* leave addresses as numbers */
  64 int Nflag;                      /* remove domains from printed host names */
  65 int Oflag = 1;                  /* run filter code optimizer */
  66 int pflag;                      /* don't go promiscuous */
  67 int qflag;                      /* quick (shorter) output */
  68 int Rflag = 1;                  /* print sequence # field in AH/ESP*/
  69 int Sflag;                      /* print raw TCP sequence numbers */
  70 int tflag = 1;                  /* print packet arrival time */
  71 int vflag;                      /* verbose */
  72 int xflag;                      /* print packet in hex */
  73
  74 char *ahsecret = NULL;          /* AH secret key */
  75 char *espsecret = NULL;         /* ESP secret key */
  76
  77 int packettype;
  78
  79
  80 char *program_name;
  81
  82 int32_t thiszone;               /* seconds offset from gmt to local time */
  83
  84 /* Externs */
  85 extern void bpf_dump(struct bpf_program *, int);
  86
  87 /* Forwards */
  88 RETSIGTYPE cleanup(int);
  89 extern __dead void usage(void) __attribute__((volatile));
  90
  91 /* Length of saved portion of packet. */
  92 int snaplen = DEFAULT_SNAPLEN;
  93
  94 struct printer {
  95         pcap_handler f;
  96         int type;
  97 };
  98
  99 static struct printer printers[] = {
 100         { ether_if_print,       DLT_EN10MB },
 101         { ether_if_print,       DLT_IEEE802 },
 102         { sl_if_print,          DLT_SLIP },
 103         { sl_bsdos_if_print,    DLT_SLIP_BSDOS },
 104         { ppp_if_print,         DLT_PPP },
 105         { ppp_bsdos_if_print,   DLT_PPP_BSDOS },
 106         { fddi_if_print,        DLT_FDDI },
 107         { null_if_print,        DLT_NULL },
 108         { raw_if_print,         DLT_RAW },
 109         { atm_if_print,         DLT_ATM_RFC1483 },
 110 #ifdef DLT_CHDLC
 111         { chdlc_if_print,       DLT_CHDLC },
 112 #endif
 113         { NULL,                 0 },
 114 };
 115
 116 static pcap_handler
 117 lookup_printer(int type)
 118 {
 119         struct printer *p;
 120
 121         for (p = printers; p->f; ++p)
 122                 if (type == p->type)
 123                         return p->f;
 124
 125         error("unknown data link type 0x%x", type);
 126         /* NOTREACHED */
 127 }
 128
 129 static pcap_t *pd;
 130
 131 extern int optind;
 132 extern int opterr;
 133 extern char *optarg;
 134
 135 int
 136 main(int argc, char **argv)
 137 {
 138         register int cnt, op, i;
 139         bpf_u_int32 localnet, netmask;
 140         register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
 141         pcap_handler printer;
 142         struct bpf_program fcode;
 143         RETSIGTYPE (*oldhandler)(int);
 144         u_char *pcap_userdata;
 145         char ebuf[PCAP_ERRBUF_SIZE];
 146
 147         cnt = -1;
 148         device = NULL;
 149         infile = NULL;
 150         RFileName = NULL;
 151         WFileName = NULL;
 152         if ((cp = strrchr(argv[0], '/')) != NULL)
 153                 program_name = cp + 1;
 154         else
 155                 program_name = argv[0];
 156
 157         if (abort_on_misalignment(ebuf) < 0)
 158                 error("%s", ebuf);
 159
 160         opterr = 0;
 161         while (
 162             (op = getopt(argc, argv, "ac:deE:fF:i:lnNOpqr:Rs:StT:vw:xY")) != EOF)
 163                 switch (op) {
 164
 165                 case 'a':
 166                         ++aflag;
 167                         break;
 168
 169 #if 0
 170                 case 'A':
 171 #ifndef CRYPTO
 172                         warning("crypto code not compiled in");
 173 #endif
 174                         ahsecret = optarg;
 175                         break;
 176 #endif
 177
 178                 case 'c':
 179                         cnt = atoi(optarg);
 180                         if (cnt <= 0)
 181                                 error("invalid packet count %s", optarg);
 182                         break;
 183
 184                 case 'd':
 185                         ++dflag;
 186                         break;
 187
 188                 case 'e':
 189                         ++eflag;
 190                         break;
 191
 192                 case 'E':
 193 #ifndef CRYPTO
 194                         warning("crypto code not compiled in");
 195 #endif
 196                         espsecret = optarg;
 197                         break;
 198
 199                 case 'f':
 200                         ++fflag;
 201                         break;
 202
 203                 case 'F':
 204                         infile = optarg;
 205                         break;
 206
 207                 case 'i':
 208                         device = optarg;
 209                         break;
 210
 211                 case 'l':
 212 #ifdef HAVE_SETLINEBUF
 213                         setlinebuf(stdout);
 214 #else
 215                         setvbuf(stdout, NULL, _IOLBF, 0);
 216 #endif
 217                         break;
 218
 219                 case 'n':
 220                         ++nflag;
 221                         break;
 222
 223                 case 'N':
 224                         ++Nflag;
 225                         break;
 226
 227                 case 'O':
 228                         Oflag = 0;
 229                         break;
 230
 231                 case 'p':
 232                         ++pflag;
 233                         break;
 234
 235                 case 'q':
 236                         ++qflag;
 237                         break;
 238
 239                 case 'r':
 240                         RFileName = optarg;
 241                         break;
 242
 243                 case 'R':
 244                         Rflag = 0;
 245                         break;
 246
 247                 case 's':
 248                         snaplen = atoi(optarg);
 249                         if (snaplen <= 0)
 250                                 error("invalid snaplen %s", optarg);
 251                         break;
 252
 253                 case 'S':
 254                         ++Sflag;
 255                         break;
 256
 257                 case 't':
 258                         --tflag;
 259                         break;
 260
 261                 case 'T':
 262                         if (strcasecmp(optarg, "vat") == 0)
 263                                 packettype = PT_VAT;
 264                         else if (strcasecmp(optarg, "wb") == 0)
 265                                 packettype = PT_WB;
 266                         else if (strcasecmp(optarg, "rpc") == 0)
 267                                 packettype = PT_RPC;
 268                         else if (strcasecmp(optarg, "rtp") == 0)
 269                                 packettype = PT_RTP;
 270                         else if (strcasecmp(optarg, "rtcp") == 0)
 271                                 packettype = PT_RTCP;
 272                         else if (strcasecmp(optarg, "snmp") == 0)
 273                                 packettype = PT_SNMP;
 274                         else
 275                                 error("unknown packet type `%s'", optarg);
 276                         break;
 277
 278                 case 'v':
 279                         ++vflag;
 280                         break;
 281
 282                 case 'w':
 283                         WFileName = optarg;
 284                         break;
 285 #ifdef YYDEBUG
 286                 case 'Y':
 287                         {
 288                         /* Undocumented flag */
 289                         extern int yydebug;
 290                         yydebug = 1;
 291                         }
 292                         break;
 293 #endif
 294                 case 'x':
 295                         ++xflag;
 296                         break;
 297
 298                 default:
 299                         usage();
 300                         /* NOTREACHED */
 301                 }
 302
 303         if (aflag && nflag)
 304                 error("-a and -n options are incompatible");
 305
 306         if (tflag > 0)
 307                 thiszone = gmt2local(0);
 308
 309         if (RFileName != NULL) {
 310                 /*
 311                  * We don't need network access, so set it back to the user id.
 312                  * Also, this prevents the user from reading anyone's
 313                  * trace file.
 314                  */
 315                 setuid(getuid());
 316
 317                 pd = pcap_open_offline(RFileName, ebuf);
 318                 if (pd == NULL)
 319                         error("%s", ebuf);
 320                 localnet = 0;
 321                 netmask = 0;
 322                 if (fflag != 0)
 323                         error("-f and -r options are incompatible");
 324         } else {
 325                 if (device == NULL) {
 326                         device = pcap_lookupdev(ebuf);
 327                         if (device == NULL)
 328                                 error("%s", ebuf);
 329                 }
 330                 pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
 331                 if (pd == NULL)
 332                         error("%s", ebuf);
 333                 i = pcap_snapshot(pd);
 334                 if (snaplen < i) {
 335                         warning("snaplen raised from %d to %d", snaplen, i);
 336                         snaplen = i;
 337                 }
 338                 if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 339                         localnet = 0;
 340                         netmask = 0;
 341                         warning("%s", ebuf);
 342                 }
 343                 /*
 344                  * Let user own process after socket has been opened.
 345                  */
 346                 setuid(getuid());
 347         }
 348         if (infile)
 349                 cmdbuf = read_infile(infile);
 350         else
 351                 cmdbuf = copy_argv(&argv[optind]);
 352
 353         if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
 354                 error("%s", pcap_geterr(pd));
 355         if (dflag) {
 356                 bpf_dump(&fcode, dflag);
 357                 exit(0);
 358         }
 359         init_addrtoname(localnet, netmask);
 360
 361         (void)setsignal(SIGTERM, cleanup);
 362         (void)setsignal(SIGINT, cleanup);
 363         /* Cooperate with nohup(1) */
 364         if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 365                 (void)setsignal(SIGHUP, oldhandler);
 366
 367         if (pcap_setfilter(pd, &fcode) < 0)
 368                 error("%s", pcap_geterr(pd));
 369         if (WFileName) {
 370                 pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
 371                 if (p == NULL)
 372                         error("%s", pcap_geterr(pd));
 373                 printer = pcap_dump;
 374                 pcap_userdata = (u_char *)p;
 375         } else {
 376                 printer = lookup_printer(pcap_datalink(pd));
 377                 pcap_userdata = 0;
 378         }
 379         if (RFileName == NULL) {
 380                 (void)fprintf(stderr, "%s: listening on %s\n",
 381                     program_name, device);
 382                 (void)fflush(stderr);
 383         }
 384         if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
 385                 (void)fprintf(stderr, "%s: pcap_loop: %s\n",
 386                     program_name, pcap_geterr(pd));
 387                 exit(1);
 388         }
 389         pcap_close(pd);
 390         exit(0);
 391 }
 392
 393 /* make a clean exit on interrupts */
 394 RETSIGTYPE
 395 cleanup(int signo)
 396 {
 397         struct pcap_stat stat;
 398
 399         /* Can't print the summary if reading from a savefile */
 400         if (pd != NULL && pcap_file(pd) == NULL) {
 401                 (void)fflush(stdout);
 402                 putc('\n', stderr);
 403                 if (pcap_stats(pd, &stat) < 0)
 404                         (void)fprintf(stderr, "pcap_stats: %s\n",
 405                             pcap_geterr(pd));
 406                 else {
 407                         (void)fprintf(stderr, "%d packets received by filter\n",
 408                             stat.ps_recv);
 409                         (void)fprintf(stderr, "%d packets dropped by kernel\n",
 410                             stat.ps_drop);
 411                 }
 412         }
 413         exit(0);
 414 }
 415
 416 /* Like default_print() but data need not be aligned */
 417 void
 418 default_print_unaligned(register const u_char *cp, register u_int length)
 419 {
 420   register u_int i, s;
 421   register int nshorts;
 422
 423   char line[81];
 424
 425   nshorts = (u_int) length / sizeof(u_short);
 426   i = 0;
 427   memset(line, ' ', 80);
 428   line[81]='\0';
 429
 430   putchar('\n');
 431   while (nshorts >= 0) {
 432
 433     snprintf(line+20+i*5, 7, "%02x%02x  ", cp[0], cp[1]);
 434
 435     if(isprint(cp[0])) {
 436       line[62+i*2]=cp[0];
 437     } else {
 438       line[62+i*2]='.';
 439     }
 440     if(isprint(cp[1])) {
 441       line[62+i*2+1]=cp[1];
 442     } else {
 443       line[62+i*2+1]='.';
 444     }
 445     i++;
 446     if (i == 8) {
 447       line[60]=' ';
 448       line[61]=' ';
 449       line[62+16]='\0';
 450       puts(line);
 451       i=0;
 452     }
 453     cp += 2;
 454     nshorts--;
 455   }
 456 }
 457
 458 /*
 459  * By default, print the packet out in hex.
 460  *
 461  * (BTW, please don't send us patches to print the packet out in ascii)
 462  */
 463 void
 464 default_print(register const u_char *bp, register u_int length)
 465 {
 466         register const u_short *sp;
 467         register u_int i;
 468         register int nshorts;
 469
 470         default_print_unaligned(bp, length);
 471 }
 472
 473 __dead void
 474 usage(void)
 475 {
 476         extern char version[];
 477         extern char pcap_version[];
 478
 479         (void)fprintf(stderr, "%s version %s\n", program_name, version);
 480         (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
 481         (void)fprintf(stderr,
 482 "Usage: %s [-adeflnNOpqStvx] [-c count] [ -F file ]\n", program_name);
 483         (void)fprintf(stderr,
 484 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
 485         (void)fprintf(stderr,
 486 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
 487         exit(-1);
 488 }