The Tcpdump Group git mirrors - libpcap/blob - savefile.c

   1 /*
   2  * Copyright (c) 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  * savefile.c - supports offline use of tcpdump
  22  *      Extraction/creation by Jeffrey Mogul, DECWRL
  23  *      Modified by Steve McCanne, LBL.
  24  *
  25  * Used to save the received packet headers, after filtering, to
  26  * a file, and then read them later.
  27  * The first record in the file contains saved values for the machine
  28  * dependent values so we can print the dump file on any architecture.
  29  */
  30
  31 #ifdef HAVE_CONFIG_H
  32 #include <config.h>
  33 #endif
  34
  35 #include <pcap-types.h>
  36 #ifdef _WIN32
  37 #include <io.h>
  38 #include <fcntl.h>
  39 #endif /* _WIN32 */
  40
  41 #include <errno.h>
  42 #include <memory.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <limits.h> /* for INT_MAX */
  47
  48 #include "pcap-int.h"
  49
  50 #ifdef HAVE_OS_PROTO_H
  51 #include "os-proto.h"
  52 #endif
  53
  54 #include "sf-pcap.h"
  55 #include "sf-pcapng.h"
  56 #include "pcap-common.h"
  57 #include "charconv.h"
  58
  59 #ifdef _WIN32
  60 /*
  61  * This isn't exported on Windows, because it would only work if both
  62  * WinPcap/Npcap and the code using it were to use the Universal CRT; otherwise,
  63  * a FILE structure in WinPcap/Npcap and a FILE structure in the code using it
  64  * could be different if they're using different versions of the C runtime.
  65  *
  66  * Instead, pcap/pcap.h defines it as a macro that wraps the hopen version,
  67  * with the wrapper calling _fileno() and _get_osfhandle() themselves,
  68  * so that it convert the appropriate CRT version's FILE structure to
  69  * a HANDLE (which is OS-defined, not CRT-defined, and is part of the Win32
  70  * and Win64 ABIs).
  71  */
  72 static pcap_t *pcap_fopen_offline_with_tstamp_precision(FILE *, u_int, char *);
  73 #endif
  74
  75 /*
  76  * Setting O_BINARY on DOS/Windows is a bit tricky
  77  */
  78 #if defined(_WIN32)
  79   #define SET_BINMODE(f)  _setmode(_fileno(f), _O_BINARY)
  80 #elif defined(MSDOS)
  81   #if defined(__HIGHC__)
  82   #define SET_BINMODE(f)  setmode(f, O_BINARY)
  83   #else
  84   #define SET_BINMODE(f)  setmode(fileno(f), O_BINARY)
  85   #endif
  86 #endif
  87
  88 static int
  89 sf_getnonblock(pcap_t *p _U_)
  90 {
  91         /*
  92          * This is a savefile, not a live capture file, so never say
  93          * it's in non-blocking mode.
  94          */
  95         return (0);
  96 }
  97
  98 static int
  99 sf_setnonblock(pcap_t *p, int nonblock _U_)
 100 {
 101         /*
 102          * This is a savefile, not a live capture file, so reject
 103          * requests to put it in non-blocking mode.  (If it's a
 104          * pipe, it could be put in non-blocking mode, but that
 105          * would significantly complicate the code to read packets,
 106          * as it would have to handle reading partial packets and
 107          * keeping the state of the read.)
 108          */
 109         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 110             "Savefiles cannot be put into non-blocking mode");
 111         return (-1);
 112 }
 113
 114 static int
 115 sf_stats(pcap_t *p, struct pcap_stat *ps _U_)
 116 {
 117         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 118             "Statistics aren't available from savefiles");
 119         return (-1);
 120 }
 121
 122 #ifdef _WIN32
 123 static struct pcap_stat *
 124 sf_stats_ex(pcap_t *p, int *size _U_)
 125 {
 126         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 127             "Statistics aren't available from savefiles");
 128         return (NULL);
 129 }
 130
 131 static int
 132 sf_setbuff(pcap_t *p, int dim _U_)
 133 {
 134         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 135             "The kernel buffer size cannot be set while reading from a file");
 136         return (-1);
 137 }
 138
 139 static int
 140 sf_setmode(pcap_t *p, int mode _U_)
 141 {
 142         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 143             "impossible to set mode while reading from a file");
 144         return (-1);
 145 }
 146
 147 static int
 148 sf_setmintocopy(pcap_t *p, int size _U_)
 149 {
 150         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 151             "The mintocopy parameter cannot be set while reading from a file");
 152         return (-1);
 153 }
 154
 155 static HANDLE
 156 sf_getevent(pcap_t *pcap)
 157 {
 158         (void)snprintf(pcap->errbuf, sizeof(pcap->errbuf),
 159             "The read event cannot be retrieved while reading from a file");
 160         return (INVALID_HANDLE_VALUE);
 161 }
 162
 163 static int
 164 sf_oid_get_request(pcap_t *p, bpf_u_int32 oid _U_, void *data _U_,
 165     size_t *lenp _U_)
 166 {
 167         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 168             "An OID get request cannot be performed on a file");
 169         return (PCAP_ERROR);
 170 }
 171
 172 static int
 173 sf_oid_set_request(pcap_t *p, bpf_u_int32 oid _U_, const void *data _U_,
 174     size_t *lenp _U_)
 175 {
 176         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 177             "An OID set request cannot be performed on a file");
 178         return (PCAP_ERROR);
 179 }
 180
 181 static u_int
 182 sf_sendqueue_transmit(pcap_t *p, pcap_send_queue *queue _U_, int sync _U_)
 183 {
 184         pcap_strlcpy(p->errbuf, "Sending packets isn't supported on savefiles",
 185             PCAP_ERRBUF_SIZE);
 186         return (0);
 187 }
 188
 189 static int
 190 sf_setuserbuffer(pcap_t *p, int size _U_)
 191 {
 192         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 193             "The user buffer cannot be set when reading from a file");
 194         return (-1);
 195 }
 196
 197 static int
 198 sf_live_dump(pcap_t *p, char *filename _U_, int maxsize _U_, int maxpacks _U_)
 199 {
 200         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 201             "Live packet dumping cannot be performed when reading from a file");
 202         return (-1);
 203 }
 204
 205 static int
 206 sf_live_dump_ended(pcap_t *p, int sync _U_)
 207 {
 208         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 209             "Live packet dumping cannot be performed on a pcap_open_dead pcap_t");
 210         return (-1);
 211 }
 212
 213 static PAirpcapHandle
 214 sf_get_airpcap_handle(pcap_t *pcap _U_)
 215 {
 216         return (NULL);
 217 }
 218 #endif
 219
 220 static int
 221 sf_inject(pcap_t *p, const void *buf _U_, int size _U_)
 222 {
 223         pcap_strlcpy(p->errbuf, "Sending packets isn't supported on savefiles",
 224             PCAP_ERRBUF_SIZE);
 225         return (-1);
 226 }
 227
 228 /*
 229  * Set direction flag: Which packets do we accept on a forwarding
 230  * single device? IN, OUT or both?
 231  */
 232 static int
 233 sf_setdirection(pcap_t *p, pcap_direction_t d _U_)
 234 {
 235         snprintf(p->errbuf, sizeof(p->errbuf),
 236             "Setting direction is not supported on savefiles");
 237         return (-1);
 238 }
 239
 240 void
 241 sf_cleanup(pcap_t *p)
 242 {
 243         if (p->rfile != stdin)
 244                 (void)fclose(p->rfile);
 245         if (p->buffer != NULL)
 246                 free(p->buffer);
 247         pcap_freecode(&p->fcode);
 248 }
 249
 250 #ifdef _WIN32
 251 /*
 252  * Wrapper for fopen() and _wfopen().
 253  *
 254  * If we're in UTF-8 mode, map the pathname from UTF-8 to UTF-16LE and
 255  * call _wfopen().
 256  *
 257  * If we're not, just use fopen(); that'll treat it as being in the
 258  * local code page.
 259  */
 260 FILE *
 261 charset_fopen(const char *path, const char *mode)
 262 {
 263         wchar_t *utf16_path;
 264 #define MAX_MODE_LEN    16
 265         wchar_t utf16_mode[MAX_MODE_LEN+1];
 266         int i;
 267         char c;
 268         FILE *fp;
 269         int save_errno;
 270
 271         if (pcap_utf_8_mode) {
 272                 /*
 273                  * Map from UTF-8 to UTF-16LE.
 274                  * Fail if there are invalid characters in the input
 275                  * string, rather than converting them to REPLACEMENT
 276                  * CHARACTER; the latter is appropriate for strings
 277                  * to be displayed to the user, but for file names
 278                  * you just want the attempt to open the file to fail.
 279                  */
 280                 utf16_path = cp_to_utf_16le(CP_UTF8, path,
 281                     MB_ERR_INVALID_CHARS);
 282                 if (utf16_path == NULL) {
 283                         /*
 284                          * Error.  Assume errno has been set.
 285                          *
 286                          * XXX - what about Windows errors?
 287                          */
 288                         return (NULL);
 289                 }
 290
 291                 /*
 292                  * Now convert the mode to UTF-16LE as well.
 293                  * We assume the mode is ASCII, and that
 294                  * it's short, so that's easy.
 295                  */
 296                 for (i = 0; (c = *mode) != '\0'; i++, mode++) {
 297                         if (c > 0x7F) {
 298                                 /* Not an ASCII character; fail with EINVAL. */
 299                                 free(utf16_path);
 300                                 errno = EINVAL;
 301                                 return (NULL);
 302                         }
 303                         if (i >= MAX_MODE_LEN) {
 304                                 /* The mode string is longer than we allow. */
 305                                 free(utf16_path);
 306                                 errno = EINVAL;
 307                                 return (NULL);
 308                         }
 309                         utf16_mode[i] = c;
 310                 }
 311                 utf16_mode[i] = '\0';
 312
 313                 /*
 314                  * OK, we have UTF-16LE strings; hand them to
 315                  * _wfopen().
 316                  */
 317                 fp = _wfopen(utf16_path, utf16_mode);
 318
 319                 /*
 320                  * Make sure freeing the UTF-16LE string doesn't
 321                  * overwrite the error code we got from _wfopen().
 322                  */
 323                 save_errno = errno;
 324                 free(utf16_path);
 325                 errno = save_errno;
 326
 327                 return (fp);
 328         } else {
 329                 /*
 330                  * This takes strings in the local code page as an
 331                  * argument.
 332                  */
 333                 return (fopen(path, mode));
 334         }
 335 }
 336 #endif
 337
 338 pcap_t *
 339 pcap_open_offline_with_tstamp_precision(const char *fname, u_int precision,
 340                                         char *errbuf)
 341 {
 342         FILE *fp;
 343         pcap_t *p;
 344
 345         if (fname == NULL) {
 346                 snprintf(errbuf, PCAP_ERRBUF_SIZE,
 347                     "A null pointer was supplied as the file name");
 348                 return (NULL);
 349         }
 350         if (fname[0] == '-' && fname[1] == '\0')
 351         {
 352                 fp = stdin;
 353                 if (fp == NULL) {
 354                         snprintf(errbuf, PCAP_ERRBUF_SIZE,
 355                             "The standard input is not open");
 356                         return (NULL);
 357                 }
 358 #if defined(_WIN32) || defined(MSDOS)
 359                 /*
 360                  * We're reading from the standard input, so put it in binary
 361                  * mode, as savefiles are binary files.
 362                  */
 363                 SET_BINMODE(fp);
 364 #endif
 365         }
 366         else {
 367                 /*
 368                  * Use charset_fopen(); on Windows, it tests whether we're
 369                  * in "local code page" or "UTF-8" mode, and treats the
 370                  * pathname appropriately, and on other platforms, it just
 371                  * wraps fopen().
 372                  *
 373                  * "b" is supported as of C90, so *all* UN*Xes should
 374                  * support it, even though it does nothing.  For MS-DOS,
 375                  * we again need it.
 376                  */
 377                 fp = charset_fopen(fname, "rb");
 378                 if (fp == NULL) {
 379                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 380                             errno, "%s", fname);
 381                         return (NULL);
 382                 }
 383         }
 384         p = pcap_fopen_offline_with_tstamp_precision(fp, precision, errbuf);
 385         if (p == NULL) {
 386                 if (fp != stdin)
 387                         fclose(fp);
 388         }
 389         return (p);
 390 }
 391
 392 pcap_t *
 393 pcap_open_offline(const char *fname, char *errbuf)
 394 {
 395         return (pcap_open_offline_with_tstamp_precision(fname,
 396             PCAP_TSTAMP_PRECISION_MICRO, errbuf));
 397 }
 398
 399 #ifdef _WIN32
 400 pcap_t* pcap_hopen_offline_with_tstamp_precision(intptr_t osfd, u_int precision,
 401     char *errbuf)
 402 {
 403         int fd;
 404         FILE *file;
 405
 406         fd = _open_osfhandle(osfd, _O_RDONLY);
 407         if ( fd < 0 )
 408         {
 409                 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 410                     errno, "_open_osfhandle");
 411                 return NULL;
 412         }
 413
 414         file = _fdopen(fd, "rb");
 415         if ( file == NULL )
 416         {
 417                 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 418                     errno, "_fdopen");
 419                 _close(fd);
 420                 return NULL;
 421         }
 422
 423         return pcap_fopen_offline_with_tstamp_precision(file, precision,
 424             errbuf);
 425 }
 426
 427 pcap_t* pcap_hopen_offline(intptr_t osfd, char *errbuf)
 428 {
 429         return pcap_hopen_offline_with_tstamp_precision(osfd,
 430             PCAP_TSTAMP_PRECISION_MICRO, errbuf);
 431 }
 432 #endif
 433
 434 /*
 435  * Given a link-layer header type and snapshot length, return a
 436  * snapshot length to use when reading the file; it's guaranteed
 437  * to be > 0 and <= INT_MAX.
 438  *
 439  * XXX - the only reason why we limit it to <= INT_MAX is so that
 440  * it fits in p->snapshot, and the only reason that p->snapshot is
 441  * signed is that pcap_snapshot() returns an int, not an unsigned int.
 442  */
 443 bpf_u_int32
 444 pcap_adjust_snapshot(bpf_u_int32 linktype, bpf_u_int32 snaplen)
 445 {
 446         if (snaplen == 0 || snaplen > INT_MAX) {
 447                 /*
 448                  * Bogus snapshot length; use the maximum for this
 449                  * link-layer type as a fallback.
 450                  *
 451                  * XXX - we don't clamp snapshot lengths that are
 452                  * <= INT_MAX but > max_snaplen_for_dlt(linktype),
 453                  * so a capture file could cause us to allocate
 454                  * a Really Big Buffer.
 455                  */
 456                 snaplen = max_snaplen_for_dlt(linktype);
 457         }
 458         return snaplen;
 459 }
 460
 461 static pcap_t *(*check_headers[])(const uint8_t *, FILE *, u_int, char *, int *) = {
 462         pcap_check_header,
 463         pcap_ng_check_header
 464 };
 465
 466 #define N_FILE_TYPES    (sizeof check_headers / sizeof check_headers[0])
 467
 468 #ifdef _WIN32
 469 static
 470 #endif
 471 pcap_t *
 472 pcap_fopen_offline_with_tstamp_precision(FILE *fp, u_int precision,
 473     char *errbuf)
 474 {
 475         register pcap_t *p;
 476         uint8_t magic[4];
 477         size_t amt_read;
 478         u_int i;
 479         int err;
 480
 481         /*
 482          * Fail if we were passed a NULL fp.
 483          *
 484          * That shouldn't happen if we're opening with a path name, but
 485          * it could happen if buggy code is opening with a FILE * and
 486          * didn't bother to make sure the FILE * isn't null.
 487          */
 488         if (fp == NULL) {
 489                 snprintf(errbuf, PCAP_ERRBUF_SIZE,
 490                     "Null FILE * pointer provided to savefile open routine");
 491                 return (NULL);
 492         }
 493
 494         /*
 495          * Read the first 4 bytes of the file; the network analyzer dump
 496          * file formats we support (pcap and pcapng), and several other
 497          * formats we might support in the future (such as snoop, DOS and
 498          * Windows Sniffer, and Microsoft Network Monitor) all have magic
 499          * numbers that are unique in their first 4 bytes.
 500          */
 501         amt_read = fread(&magic, 1, sizeof(magic), fp);
 502         if (amt_read != sizeof(magic)) {
 503                 if (ferror(fp)) {
 504                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 505                             errno, "error reading dump file");
 506                 } else {
 507                         snprintf(errbuf, PCAP_ERRBUF_SIZE,
 508                             "truncated dump file; tried to read %zu file header bytes, only got %zu",
 509                             sizeof(magic), amt_read);
 510                 }
 511                 return (NULL);
 512         }
 513
 514         /*
 515          * Try all file types.
 516          */
 517         for (i = 0; i < N_FILE_TYPES; i++) {
 518                 p = (*check_headers[i])(magic, fp, precision, errbuf, &err);
 519                 if (p != NULL) {
 520                         /* Yup, that's it. */
 521                         goto found;
 522                 }
 523                 if (err) {
 524                         /*
 525                          * Error trying to read the header.
 526                          */
 527                         return (NULL);
 528                 }
 529         }
 530
 531         /*
 532          * Well, who knows what this mess is....
 533          */
 534         snprintf(errbuf, PCAP_ERRBUF_SIZE, "unknown file format");
 535         return (NULL);
 536
 537 found:
 538         p->rfile = fp;
 539
 540         /* Padding only needed for live capture fcode */
 541         p->fddipad = 0;
 542
 543 #if !defined(_WIN32) && !defined(MSDOS)
 544         /*
 545          * You can do "select()" and "poll()" on plain files on most
 546          * platforms, and should be able to do so on pipes.
 547          *
 548          * You can't do "select()" on anything other than sockets in
 549          * Windows, so, on Win32 systems, we don't have "selectable_fd".
 550          */
 551         p->selectable_fd = fileno(fp);
 552 #endif
 553
 554         p->read_op = pcap_offline_read;
 555         p->inject_op = sf_inject;
 556         p->setfilter_op = install_bpf_program;
 557         p->setdirection_op = sf_setdirection;
 558         p->set_datalink_op = NULL;      /* we don't support munging link-layer headers */
 559         p->getnonblock_op = sf_getnonblock;
 560         p->setnonblock_op = sf_setnonblock;
 561         p->stats_op = sf_stats;
 562 #ifdef _WIN32
 563         p->stats_ex_op = sf_stats_ex;
 564         p->setbuff_op = sf_setbuff;
 565         p->setmode_op = sf_setmode;
 566         p->setmintocopy_op = sf_setmintocopy;
 567         p->getevent_op = sf_getevent;
 568         p->oid_get_request_op = sf_oid_get_request;
 569         p->oid_set_request_op = sf_oid_set_request;
 570         p->sendqueue_transmit_op = sf_sendqueue_transmit;
 571         p->setuserbuffer_op = sf_setuserbuffer;
 572         p->live_dump_op = sf_live_dump;
 573         p->live_dump_ended_op = sf_live_dump_ended;
 574         p->get_airpcap_handle_op = sf_get_airpcap_handle;
 575 #endif
 576
 577         /*
 578          * For offline captures, the standard one-shot callback can
 579          * be used for pcap_next()/pcap_next_ex().
 580          */
 581         p->oneshot_callback = pcap_oneshot;
 582
 583         /*
 584          * Default breakloop operation.
 585          */
 586         p->breakloop_op = pcap_breakloop_common;
 587
 588         /*
 589          * Savefiles never require special BPF code generation.
 590          */
 591         p->bpf_codegen_flags = 0;
 592
 593         p->activated = 1;
 594
 595         return (p);
 596 }
 597
 598 /*
 599  * This isn't needed on Windows; we #define pcap_fopen_offline() as
 600  * a wrapper around pcap_hopen_offline(), and we don't call it from
 601  * inside this file, so it's unused.
 602  */
 603 #ifndef _WIN32
 604 pcap_t *
 605 pcap_fopen_offline(FILE *fp, char *errbuf)
 606 {
 607         return (pcap_fopen_offline_with_tstamp_precision(fp,
 608             PCAP_TSTAMP_PRECISION_MICRO, errbuf));
 609 }
 610 #endif
 611
 612 /*
 613  * Read packets from a capture file, and call the callback for each
 614  * packet.
 615  * If cnt > 0, return after 'cnt' packets, otherwise continue until eof.
 616  */
 617 int
 618 pcap_offline_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
 619 {
 620         struct bpf_insn *fcode;
 621         int n = 0;
 622         u_char *data;
 623
 624         for (;;) {
 625                 struct pcap_pkthdr h;
 626                 int status;
 627
 628                 /*
 629                  * Has "pcap_breakloop()" been called?
 630                  * If so, return immediately - if we haven't read any
 631                  * packets, clear the flag and return -2 to indicate
 632                  * that we were told to break out of the loop, otherwise
 633                  * leave the flag set, so that the *next* call will break
 634                  * out of the loop without having read any packets, and
 635                  * return the number of packets we've processed so far.
 636                  */
 637                 if (p->break_loop) {
 638                         if (n == 0) {
 639                                 p->break_loop = 0;
 640                                 return (-2);
 641                         } else
 642                                 return (n);
 643                 }
 644
 645                 status = p->next_packet_op(p, &h, &data);
 646                 if (status < 0) {
 647                         /*
 648                          * Error.  Pass it back to the caller.
 649                          */
 650                         return (status);
 651                 }
 652                 if (status == 0) {
 653                         /*
 654                          * EOF.  Nothing more to process;
 655                          */
 656                         break;
 657                 }
 658
 659                 /*
 660                  * OK, we've read a packet; run it through the filter
 661                  * and, if it passes, process it.
 662                  */
 663                 if ((fcode = p->fcode.bf_insns) == NULL ||
 664                     pcap_filter(fcode, data, h.len, h.caplen)) {
 665                         (*callback)(user, &h, data);
 666                         n++;    /* count the packet */
 667                         if (!PACKET_COUNT_IS_UNLIMITED(cnt) && n >= cnt)
 668                                 break;
 669                 }
 670         }
 671         /*XXX this breaks semantics tcpslice expects */
 672         return (n);
 673 }