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 #include <config.h>
  32
  33 #include <pcap-types.h>
  34 #ifdef _WIN32
  35 #include <io.h>
  36 #include <fcntl.h>
  37 #endif /* _WIN32 */
  38
  39 #include <errno.h>
  40 #include <memory.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <limits.h> /* for INT_MAX */
  45
  46 #include "pcap-int.h"
  47
  48 #ifdef HAVE_OS_PROTO_H
  49 #include "os-proto.h"
  50 #endif
  51
  52 #include "sf-pcap.h"
  53 #include "sf-pcapng.h"
  54 #include "pcap-common.h"
  55 #include "charconv.h"
  56
  57 #ifdef _WIN32
  58 /*
  59  * This isn't exported on Windows, because it would only work if both
  60  * WinPcap/Npcap and the code using it were to use the Universal CRT; otherwise,
  61  * a FILE structure in WinPcap/Npcap and a FILE structure in the code using it
  62  * could be different if they're using different versions of the C runtime.
  63  *
  64  * Instead, pcap/pcap.h defines it as a macro that wraps the hopen version,
  65  * with the wrapper calling _fileno() and _get_osfhandle() themselves,
  66  * so that it convert the appropriate CRT version's FILE structure to
  67  * a HANDLE (which is OS-defined, not CRT-defined, and is part of the Win32
  68  * and Win64 ABIs).
  69  */
  70 static pcap_t *pcap_fopen_offline_with_tstamp_precision(FILE *, u_int, char *);
  71 #endif
  72
  73 /*
  74  * Setting O_BINARY on Windows is a bit tricky.
  75  */
  76 #if defined(_WIN32)
  77   #define SET_BINMODE(f)  _setmode(_fileno(f), _O_BINARY)
  78 #endif
  79
  80 static int
  81 sf_getnonblock(pcap_t *p _U_)
  82 {
  83         /*
  84          * This is a savefile, not a live capture file, so never say
  85          * it's in non-blocking mode.
  86          */
  87         return (0);
  88 }
  89
  90 static int
  91 sf_setnonblock(pcap_t *p, int nonblock _U_)
  92 {
  93         /*
  94          * This is a savefile, not a live capture file, so reject
  95          * requests to put it in non-blocking mode.  (If it's a
  96          * pipe, it could be put in non-blocking mode, but that
  97          * would significantly complicate the code to read packets,
  98          * as it would have to handle reading partial packets and
  99          * keeping the state of the read.)
 100          */
 101         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 102             "Savefiles cannot be put into non-blocking mode");
 103         return (-1);
 104 }
 105
 106 static int
 107 sf_cant_set_rfmon(pcap_t *p _U_)
 108 {
 109         /*
 110          * This is a savefile, not a device on which you can capture,
 111          * so never say it supports being put into monitor mode.
 112          */
 113         return (0);
 114 }
 115
 116 static int
 117 sf_stats(pcap_t *p, struct pcap_stat *ps _U_)
 118 {
 119         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 120             "Statistics aren't available from savefiles");
 121         return (-1);
 122 }
 123
 124 #ifdef _WIN32
 125 static struct pcap_stat *
 126 sf_stats_ex(pcap_t *p, int *size _U_)
 127 {
 128         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 129             "Statistics aren't available from savefiles");
 130         return (NULL);
 131 }
 132
 133 static int
 134 sf_setbuff(pcap_t *p, int dim _U_)
 135 {
 136         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 137             "The kernel buffer size cannot be set while reading from a file");
 138         return (-1);
 139 }
 140
 141 static int
 142 sf_setmode(pcap_t *p, int mode _U_)
 143 {
 144         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 145             "impossible to set mode while reading from a file");
 146         return (-1);
 147 }
 148
 149 static int
 150 sf_setmintocopy(pcap_t *p, int size _U_)
 151 {
 152         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 153             "The mintocopy parameter cannot be set while reading from a file");
 154         return (-1);
 155 }
 156
 157 static HANDLE
 158 sf_getevent(pcap_t *pcap)
 159 {
 160         (void)snprintf(pcap->errbuf, sizeof(pcap->errbuf),
 161             "The read event cannot be retrieved while reading from a file");
 162         return (INVALID_HANDLE_VALUE);
 163 }
 164
 165 static int
 166 sf_oid_get_request(pcap_t *p, bpf_u_int32 oid _U_, void *data _U_,
 167     size_t *lenp _U_)
 168 {
 169         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 170             "An OID get request cannot be performed on a file");
 171         return (PCAP_ERROR);
 172 }
 173
 174 static int
 175 sf_oid_set_request(pcap_t *p, bpf_u_int32 oid _U_, const void *data _U_,
 176     size_t *lenp _U_)
 177 {
 178         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 179             "An OID set request cannot be performed on a file");
 180         return (PCAP_ERROR);
 181 }
 182
 183 static u_int
 184 sf_sendqueue_transmit(pcap_t *p, pcap_send_queue *queue _U_, int sync _U_)
 185 {
 186         pcapint_strlcpy(p->errbuf, "Sending packets isn't supported on savefiles",
 187             PCAP_ERRBUF_SIZE);
 188         return (0);
 189 }
 190
 191 static int
 192 sf_setuserbuffer(pcap_t *p, int size _U_)
 193 {
 194         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 195             "The user buffer cannot be set when reading from a file");
 196         return (-1);
 197 }
 198
 199 static int
 200 sf_live_dump(pcap_t *p, char *filename _U_, int maxsize _U_, int maxpacks _U_)
 201 {
 202         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 203             "Live packet dumping cannot be performed when reading from a file");
 204         return (-1);
 205 }
 206
 207 static int
 208 sf_live_dump_ended(pcap_t *p, int sync _U_)
 209 {
 210         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 211             "Live packet dumping cannot be performed on a pcap_open_dead pcap_t");
 212         return (-1);
 213 }
 214 #endif
 215
 216 static int
 217 sf_inject(pcap_t *p, const void *buf _U_, int size _U_)
 218 {
 219         pcapint_strlcpy(p->errbuf, "Sending packets isn't supported on savefiles",
 220             PCAP_ERRBUF_SIZE);
 221         return (-1);
 222 }
 223
 224 /*
 225  * Set direction flag: Which packets do we accept on a forwarding
 226  * single device? IN, OUT or both?
 227  */
 228 static int
 229 sf_setdirection(pcap_t *p, pcap_direction_t d _U_)
 230 {
 231         snprintf(p->errbuf, sizeof(p->errbuf),
 232             "Setting direction is not supported on savefiles");
 233         return (-1);
 234 }
 235
 236 void
 237 pcapint_sf_cleanup(pcap_t *p)
 238 {
 239         if (p->rfile != stdin)
 240                 (void)fclose(p->rfile);
 241         if (p->buffer != NULL)
 242                 free(p->buffer);
 243         pcap_freecode(&p->fcode);
 244 }
 245
 246 #ifdef _WIN32
 247 /*
 248  * Wrapper for fopen() and _wfopen().
 249  *
 250  * If we're in UTF-8 mode, map the pathname from UTF-8 to UTF-16LE and
 251  * call _wfopen().
 252  *
 253  * If we're not, just use fopen(); that'll treat it as being in the
 254  * local code page.
 255  */
 256 FILE *
 257 pcapint_charset_fopen(const char *path, const char *mode)
 258 {
 259         wchar_t *utf16_path;
 260 #define MAX_MODE_LEN    16
 261         wchar_t utf16_mode[MAX_MODE_LEN+1];
 262         int i;
 263         char c;
 264         FILE *fp;
 265         int save_errno;
 266
 267         if (pcapint_utf_8_mode) {
 268                 /*
 269                  * Map from UTF-8 to UTF-16LE.
 270                  * Fail if there are invalid characters in the input
 271                  * string, rather than converting them to REPLACEMENT
 272                  * CHARACTER; the latter is appropriate for strings
 273                  * to be displayed to the user, but for file names
 274                  * you just want the attempt to open the file to fail.
 275                  */
 276                 utf16_path = cp_to_utf_16le(CP_UTF8, path,
 277                     MB_ERR_INVALID_CHARS);
 278                 if (utf16_path == NULL) {
 279                         /*
 280                          * Error.  Assume errno has been set.
 281                          *
 282                          * XXX - what about Windows errors?
 283                          */
 284                         return (NULL);
 285                 }
 286
 287                 /*
 288                  * Now convert the mode to UTF-16LE as well.
 289                  * We assume the mode is ASCII, and that
 290                  * it's short, so that's easy.
 291                  */
 292                 for (i = 0; (c = *mode) != '\0'; i++, mode++) {
 293                         if (c > 0x7F) {
 294                                 /* Not an ASCII character; fail with EINVAL. */
 295                                 free(utf16_path);
 296                                 errno = EINVAL;
 297                                 return (NULL);
 298                         }
 299                         if (i >= MAX_MODE_LEN) {
 300                                 /* The mode string is longer than we allow. */
 301                                 free(utf16_path);
 302                                 errno = EINVAL;
 303                                 return (NULL);
 304                         }
 305                         utf16_mode[i] = c;
 306                 }
 307                 utf16_mode[i] = '\0';
 308
 309                 /*
 310                  * OK, we have UTF-16LE strings; hand them to
 311                  * _wfopen().
 312                  */
 313                 fp = _wfopen(utf16_path, utf16_mode);
 314
 315                 /*
 316                  * Make sure freeing the UTF-16LE string doesn't
 317                  * overwrite the error code we got from _wfopen().
 318                  */
 319                 save_errno = errno;
 320                 free(utf16_path);
 321                 errno = save_errno;
 322
 323                 return (fp);
 324         } else {
 325                 /*
 326                  * This takes strings in the local code page as an
 327                  * argument.
 328                  */
 329                 return (fopen(path, mode));
 330         }
 331 }
 332 #endif
 333
 334 pcap_t *
 335 pcap_open_offline_with_tstamp_precision(const char *fname, u_int precision,
 336                                         char *errbuf)
 337 {
 338         FILE *fp;
 339         pcap_t *p;
 340
 341         if (fname == NULL) {
 342                 snprintf(errbuf, PCAP_ERRBUF_SIZE,
 343                     "A null pointer was supplied as the file name");
 344                 return (NULL);
 345         }
 346         if (fname[0] == '-' && fname[1] == '\0')
 347         {
 348                 fp = stdin;
 349                 if (fp == NULL) {
 350                         snprintf(errbuf, PCAP_ERRBUF_SIZE,
 351                             "The standard input is not open");
 352                         return (NULL);
 353                 }
 354 #if defined(_WIN32)
 355                 /*
 356                  * We're reading from the standard input, so put it in binary
 357                  * mode, as savefiles are binary files.
 358                  */
 359                 SET_BINMODE(fp);
 360 #endif
 361         }
 362         else {
 363                 /*
 364                  * Use pcapint_charset_fopen(); on Windows, it tests whether we're
 365                  * in "local code page" or "UTF-8" mode, and treats the
 366                  * pathname appropriately, and on other platforms, it just
 367                  * wraps fopen().
 368                  *
 369                  * "b" is supported as of C90, so *all* UN*Xes should
 370                  * support it, even though it does nothing.
 371                  */
 372                 fp = pcapint_charset_fopen(fname, "rb");
 373                 if (fp == NULL) {
 374                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 375                             errno, "%s", fname);
 376                         return (NULL);
 377                 }
 378         }
 379         p = pcap_fopen_offline_with_tstamp_precision(fp, precision, errbuf);
 380         if (p == NULL) {
 381                 if (fp != stdin)
 382                         fclose(fp);
 383         }
 384         return (p);
 385 }
 386
 387 pcap_t *
 388 pcap_open_offline(const char *fname, char *errbuf)
 389 {
 390         return (pcap_open_offline_with_tstamp_precision(fname,
 391             PCAP_TSTAMP_PRECISION_MICRO, errbuf));
 392 }
 393
 394 #ifdef _WIN32
 395 pcap_t* pcap_hopen_offline_with_tstamp_precision(intptr_t osfd, u_int precision,
 396     char *errbuf)
 397 {
 398         int fd;
 399         FILE *file;
 400
 401         fd = _open_osfhandle(osfd, _O_RDONLY);
 402         if ( fd < 0 )
 403         {
 404                 pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 405                     errno, "_open_osfhandle");
 406                 return NULL;
 407         }
 408
 409         file = _fdopen(fd, "rb");
 410         if ( file == NULL )
 411         {
 412                 pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 413                     errno, "_fdopen");
 414                 _close(fd);
 415                 return NULL;
 416         }
 417
 418         return pcap_fopen_offline_with_tstamp_precision(file, precision,
 419             errbuf);
 420 }
 421
 422 pcap_t* pcap_hopen_offline(intptr_t osfd, char *errbuf)
 423 {
 424         return pcap_hopen_offline_with_tstamp_precision(osfd,
 425             PCAP_TSTAMP_PRECISION_MICRO, errbuf);
 426 }
 427 #endif
 428
 429 /*
 430  * Given a link-layer header type and snapshot length, return a
 431  * snapshot length to use when reading the file; it's guaranteed
 432  * to be > 0 and <= INT_MAX.
 433  *
 434  * XXX - the only reason why we limit it to <= INT_MAX is so that
 435  * it fits in p->snapshot, and the only reason that p->snapshot is
 436  * signed is that pcap_snapshot() returns an int, not an unsigned int.
 437  */
 438 bpf_u_int32
 439 pcapint_adjust_snapshot(bpf_u_int32 linktype, bpf_u_int32 snaplen)
 440 {
 441         if (snaplen == 0 || snaplen > INT_MAX) {
 442                 /*
 443                  * Bogus snapshot length; use the maximum for this
 444                  * link-layer type as a fallback.
 445                  *
 446                  * XXX - we don't clamp snapshot lengths that are
 447                  * <= INT_MAX but > max_snaplen_for_dlt(linktype),
 448                  * so a capture file could cause us to allocate
 449                  * a Really Big Buffer.
 450                  */
 451                 snaplen = max_snaplen_for_dlt(linktype);
 452         }
 453         return snaplen;
 454 }
 455
 456 static pcap_t *(*check_headers[])(const uint8_t *, FILE *, u_int, char *, int *) = {
 457         pcap_check_header,
 458         pcap_ng_check_header
 459 };
 460
 461 #define N_FILE_TYPES    (sizeof check_headers / sizeof check_headers[0])
 462
 463 #ifdef _WIN32
 464 static
 465 #endif
 466 pcap_t *
 467 pcap_fopen_offline_with_tstamp_precision(FILE *fp, u_int precision,
 468     char *errbuf)
 469 {
 470         register pcap_t *p;
 471         uint8_t magic[4];
 472         size_t amt_read;
 473         u_int i;
 474         int err;
 475
 476         /*
 477          * Fail if we were passed a NULL fp.
 478          *
 479          * That shouldn't happen if we're opening with a path name, but
 480          * it could happen if buggy code is opening with a FILE * and
 481          * didn't bother to make sure the FILE * isn't null.
 482          */
 483         if (fp == NULL) {
 484                 snprintf(errbuf, PCAP_ERRBUF_SIZE,
 485                     "Null FILE * pointer provided to savefile open routine");
 486                 return (NULL);
 487         }
 488
 489         /*
 490          * Read the first 4 bytes of the file; the network analyzer dump
 491          * file formats we support (pcap and pcapng), and several other
 492          * formats we might support in the future (such as snoop, DOS and
 493          * Windows Sniffer, and Microsoft Network Monitor) all have magic
 494          * numbers that are unique in their first 4 bytes.
 495          */
 496         amt_read = fread(&magic, 1, sizeof(magic), fp);
 497         if (amt_read != sizeof(magic)) {
 498                 if (ferror(fp)) {
 499                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 500                             errno, "error reading dump file");
 501                 } else {
 502                         snprintf(errbuf, PCAP_ERRBUF_SIZE,
 503                             "truncated dump file; tried to read %zu file header bytes, only got %zu",
 504                             sizeof(magic), amt_read);
 505                 }
 506                 return (NULL);
 507         }
 508
 509         /*
 510          * Try all file types.
 511          */
 512         for (i = 0; i < N_FILE_TYPES; i++) {
 513                 p = (*check_headers[i])(magic, fp, precision, errbuf, &err);
 514                 if (p != NULL) {
 515                         /* Yup, that's it. */
 516                         goto found;
 517                 }
 518                 if (err) {
 519                         /*
 520                          * Error trying to read the header.
 521                          */
 522                         return (NULL);
 523                 }
 524         }
 525
 526         /*
 527          * Well, who knows what this mess is....
 528          */
 529         snprintf(errbuf, PCAP_ERRBUF_SIZE, "unknown file format");
 530         return (NULL);
 531
 532 found:
 533         p->rfile = fp;
 534
 535         /* Padding only needed for live capture fcode */
 536         p->fddipad = 0;
 537
 538 #if !defined(_WIN32)
 539         /*
 540          * You can do "select()" and "poll()" on plain files on most
 541          * platforms, and should be able to do so on pipes.
 542          *
 543          * You can't do "select()" on anything other than sockets in
 544          * Windows, so, on Win32 systems, we don't have "selectable_fd".
 545          */
 546         p->selectable_fd = fileno(fp);
 547 #endif
 548
 549         p->can_set_rfmon_op = sf_cant_set_rfmon;
 550         p->read_op = pcapint_offline_read;
 551         p->inject_op = sf_inject;
 552         p->setfilter_op = pcapint_install_bpf_program;
 553         p->setdirection_op = sf_setdirection;
 554         p->set_datalink_op = NULL;      /* we don't support munging link-layer headers */
 555         p->getnonblock_op = sf_getnonblock;
 556         p->setnonblock_op = sf_setnonblock;
 557         p->stats_op = sf_stats;
 558 #ifdef _WIN32
 559         p->stats_ex_op = sf_stats_ex;
 560         p->setbuff_op = sf_setbuff;
 561         p->setmode_op = sf_setmode;
 562         p->setmintocopy_op = sf_setmintocopy;
 563         p->getevent_op = sf_getevent;
 564         p->oid_get_request_op = sf_oid_get_request;
 565         p->oid_set_request_op = sf_oid_set_request;
 566         p->sendqueue_transmit_op = sf_sendqueue_transmit;
 567         p->setuserbuffer_op = sf_setuserbuffer;
 568         p->live_dump_op = sf_live_dump;
 569         p->live_dump_ended_op = sf_live_dump_ended;
 570 #endif
 571
 572         /*
 573          * For offline captures, the standard one-shot callback can
 574          * be used for pcap_next()/pcap_next_ex().
 575          */
 576         p->oneshot_callback = pcapint_oneshot;
 577
 578         /*
 579          * Default breakloop operation.
 580          */
 581         p->breakloop_op = pcapint_breakloop_common;
 582
 583         /*
 584          * Savefiles never require special BPF code generation.
 585          */
 586         p->bpf_codegen_flags = 0;
 587
 588         p->activated = 1;
 589
 590         return (p);
 591 }
 592
 593 /*
 594  * This isn't needed on Windows; we #define pcap_fopen_offline() as
 595  * a wrapper around pcap_hopen_offline(), and we don't call it from
 596  * inside this file, so it's unused.
 597  */
 598 #ifndef _WIN32
 599 pcap_t *
 600 pcap_fopen_offline(FILE *fp, char *errbuf)
 601 {
 602         return (pcap_fopen_offline_with_tstamp_precision(fp,
 603             PCAP_TSTAMP_PRECISION_MICRO, errbuf));
 604 }
 605 #endif
 606
 607 /*
 608  * Read packets from a capture file, and call the callback for each
 609  * packet.
 610  * If cnt > 0, return after 'cnt' packets, otherwise continue until eof.
 611  */
 612 int
 613 pcapint_offline_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
 614 {
 615         struct bpf_insn *fcode;
 616         int n = 0;
 617         u_char *data;
 618
 619         /*
 620          * This can conceivably process more than INT_MAX packets,
 621          * which would overflow the packet count, causing it either
 622          * to look like a negative number, and thus cause us to
 623          * return a value that looks like an error, or overflow
 624          * back into positive territory, and thus cause us to
 625          * return a too-low count.
 626          *
 627          * Therefore, if the packet count is unlimited, we clip
 628          * it at INT_MAX; this routine is not expected to
 629          * process packets indefinitely, so that's not an issue.
 630          */
 631         if (PACKET_COUNT_IS_UNLIMITED(cnt))
 632                 cnt = INT_MAX;
 633
 634         for (;;) {
 635                 struct pcap_pkthdr h;
 636                 int status;
 637
 638                 /*
 639                  * Has "pcap_breakloop()" been called?
 640                  * If so, return immediately - if we haven't read any
 641                  * packets, clear the flag and return -2 to indicate
 642                  * that we were told to break out of the loop, otherwise
 643                  * leave the flag set, so that the *next* call will break
 644                  * out of the loop without having read any packets, and
 645                  * return the number of packets we've processed so far.
 646                  */
 647                 if (p->break_loop) {
 648                         if (n == 0) {
 649                                 p->break_loop = 0;
 650                                 return (-2);
 651                         } else
 652                                 return (n);
 653                 }
 654
 655                 status = p->next_packet_op(p, &h, &data);
 656                 if (status < 0) {
 657                         /*
 658                          * Error.  Pass it back to the caller.
 659                          */
 660                         return (status);
 661                 }
 662                 if (status == 0) {
 663                         /*
 664                          * EOF.  Nothing more to process;
 665                          */
 666                         break;
 667                 }
 668
 669                 /*
 670                  * OK, we've read a packet; run it through the filter
 671                  * and, if it passes, process it.
 672                  */
 673                 if ((fcode = p->fcode.bf_insns) == NULL ||
 674                     pcapint_filter(fcode, data, h.len, h.caplen)) {
 675                         (*callback)(user, &h, data);
 676                         n++;    /* count the packet */
 677                         if (n >= cnt)
 678                                 break;
 679                 }
 680         }
 681         /*XXX this breaks semantics tcpslice expects */
 682         return (n);
 683 }