File: pcapio.c

package info (click to toggle)
wireshark 1.12.1+g01b65bf-4+deb8u14
  • links: PTS, VCS
  • area: main
  • in suites: jessie
  • size: 234,068 kB
  • sloc: ansic: 1,912,971; xml: 84,598; cpp: 41,923; python: 30,175; perl: 25,286; lex: 6,416; sh: 6,406; pascal: 6,120; makefile: 3,968; yacc: 297; asm: 156; awk: 58; tcl: 35
file content (744 lines) | stat: -rw-r--r-- 29,317 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
/* pcapio.c
 * Our own private code for writing libpcap files when capturing.
 *
 * We have these because we want a way to open a stream for output given
 * only a file descriptor.  libpcap 0.9[.x] has "pcap_dump_fopen()", which
 * provides that, but
 *
 *      1) earlier versions of libpcap doesn't have it
 *
 * and
 *
 *      2) WinPcap doesn't have it, because a file descriptor opened
 *         by code built for one version of the MSVC++ C library
 *         can't be used by library routines built for another version
 *         (e.g., threaded vs. unthreaded).
 *
 * Libpcap's pcap_dump() also doesn't return any error indications.
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * Derived from code in the Wiretap Library
 * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef _WIN32
#include <Windows.h>
#endif

#include <glib.h>

#include "pcapio.h"

/* Magic numbers in "libpcap" files.

   "libpcap" file records are written in the byte order of the host that
   writes them, and the reader is expected to fix this up.

   PCAP_MAGIC is the magic number, in host byte order; PCAP_SWAPPED_MAGIC
   is a byte-swapped version of that.

   PCAP_NSEC_MAGIC is for Ulf Lamping's modified "libpcap" format,
   which uses the same common file format as PCAP_MAGIC, but the
   timestamps are saved in nanosecond resolution instead of microseconds.
   PCAP_SWAPPED_NSEC_MAGIC is a byte-swapped version of that. */
#define PCAP_MAGIC                      0xa1b2c3d4
#define PCAP_SWAPPED_MAGIC              0xd4c3b2a1
#define PCAP_NSEC_MAGIC                 0xa1b23c4d
#define PCAP_SWAPPED_NSEC_MAGIC         0x4d3cb2a1

/* "libpcap" file header. */
struct pcap_hdr {
        guint32 magic;          /* magic number */
        guint16 version_major;  /* major version number */
        guint16 version_minor;  /* minor version number */
        gint32  thiszone;       /* GMT to local correction */
        guint32 sigfigs;        /* accuracy of timestamps */
        guint32 snaplen;        /* max length of captured packets, in octets */
        guint32 network;        /* data link type */
};

/* "libpcap" record header. */
struct pcaprec_hdr {
        guint32 ts_sec;         /* timestamp seconds */
        guint32 ts_usec;        /* timestamp microseconds (nsecs for PCAP_NSEC_MAGIC) */
        guint32 incl_len;       /* number of octets of packet saved in file */
        guint32 orig_len;       /* actual length of packet */
};

/* Magic numbers in ".pcapng" files.
 *
 * .pcapng file records are written in the byte order of the host that
 * writes them, and the reader is expected to fix this up.
 * PCAPNG_MAGIC is the magic number, in host byte order;
 * PCAPNG_SWAPPED_MAGIC is a byte-swapped version of that.
 */
#define PCAPNG_MAGIC         0x1A2B3C4D
#define PCAPNG_SWAPPED_MAGIC 0xD4C3B2A1

/* Currently we are only supporting the initial version of
   the file format. */
#define PCAPNG_MAJOR_VERSION 1
#define PCAPNG_MINOR_VERSION 0

/* Section Header Block without options and trailing Block Total Length */
struct shb {
        guint32 block_type;
        guint32 block_total_length;
        guint32 byte_order_magic;
        guint16 major_version;
        guint16 minor_version;
        guint64 section_length;
};
#define SECTION_HEADER_BLOCK_TYPE 0x0A0D0D0A

/* Interface Decription Block without options and trailing Block Total Length */
struct idb {
        guint32 block_type;
        guint32 block_total_length;
        guint16 link_type;
        guint16 reserved;
        guint32 snap_len;
};
#define INTERFACE_DESCRIPTION_BLOCK_TYPE 0x00000001

/* Interface Statistics Block without actual packet, options, and trailing
   Block Total Length */
struct isb {
        guint32 block_type;
        guint32 block_total_length;
        guint32 interface_id;
        guint32 timestamp_high;
        guint32 timestamp_low;
};
#define INTERFACE_STATISTICS_BLOCK_TYPE 0x00000005

/* Enhanced Packet Block without actual packet, options, and trailing
   Block Total Length */
struct epb {
        guint32 block_type;
        guint32 block_total_length;
        guint32 interface_id;
        guint32 timestamp_high;
        guint32 timestamp_low;
        guint32 captured_len;
        guint32 packet_len;
};
#define ENHANCED_PACKET_BLOCK_TYPE 0x00000006

struct option {
        guint16 type;
        guint16 value_length;
};
#define OPT_ENDOFOPT      0
#define OPT_COMMENT       1
#define EPB_FLAGS         2
#define SHB_HARDWARE      2 /* currently not used */
#define SHB_OS            3
#define SHB_USERAPPL      4
#define IDB_NAME          2
#define IDB_DESCRIPTION   3
#define IDB_IF_SPEED      8
#define IDB_TSRESOL       9
#define IDB_FILTER       11
#define IDB_OS           12
#define ISB_STARTTIME     2
#define ISB_ENDTIME       3
#define ISB_IFRECV        4
#define ISB_IFDROP        5
#define ISB_FILTERACCEPT  6
#define ISB_OSDROP        7
#define ISB_USRDELIV      8
#define ADD_PADDING(x) ((((x) + 3) >> 2) << 2)

/* Write to capture file */
static gboolean
write_to_file(FILE* pfile, const guint8* data, size_t data_length,
              guint64 *bytes_written, int *err)
{
        size_t nwritten;

        nwritten = fwrite(data, data_length, 1, pfile);
        if (nwritten != 1) {
                if (ferror(pfile)) {
                        *err = errno;
                } else {
                        *err = 0;
                }
                return FALSE;
        }

        (*bytes_written) += data_length;
        return TRUE;
}

/* Writing pcap files */

/* Write the file header to a dump file.
   Returns TRUE on success, FALSE on failure.
   Sets "*err" to an error code, or 0 for a short write, on failure*/
gboolean
libpcap_write_file_header(FILE* pfile, int linktype, int snaplen, gboolean ts_nsecs, guint64 *bytes_written, int *err)
{
        struct pcap_hdr file_hdr;

        file_hdr.magic = ts_nsecs ? PCAP_NSEC_MAGIC : PCAP_MAGIC;
        /* current "libpcap" format is 2.4 */
        file_hdr.version_major = 2;
        file_hdr.version_minor = 4;
        file_hdr.thiszone = 0;  /* XXX - current offset? */
        file_hdr.sigfigs = 0;   /* unknown, but also apparently unused */
        file_hdr.snaplen = snaplen;
        file_hdr.network = linktype;

        return write_to_file(pfile, (const guint8*)&file_hdr, sizeof(file_hdr), bytes_written, err);
}

/* Write a record for a packet to a dump file.
   Returns TRUE on success, FALSE on failure. */
gboolean
libpcap_write_packet(FILE* pfile,
                     time_t sec, guint32 usec,
                     guint32 caplen, guint32 len,
                     const guint8 *pd,
                     guint64 *bytes_written, int *err)
{
        struct pcaprec_hdr rec_hdr;

        rec_hdr.ts_sec = (guint32)sec; /* Y2.038K issue in pcap format.... */
        rec_hdr.ts_usec = usec;
        rec_hdr.incl_len = caplen;
        rec_hdr.orig_len = len;
        if (!write_to_file(pfile, (const guint8*)&rec_hdr, sizeof(rec_hdr), bytes_written, err))
                return FALSE;

        return write_to_file(pfile, pd, caplen, bytes_written, err);
}

/* Writing pcap-ng files */

static guint32
pcapng_count_string_option(const char *option_value)
{
        if ((option_value != NULL) && (strlen(option_value) > 0) && (strlen(option_value) < G_MAXUINT16)) {
                /* There's a value to write; get its length */
                return (guint32)(sizeof(struct option) +
                                 (guint16)ADD_PADDING(strlen(option_value)));
	}
	return 0; /* nothing to write */
}

static gboolean
pcapng_write_string_option(FILE* pfile,
                           guint16 option_type, const char *option_value,
                           guint64 *bytes_written, int *err)
{
        size_t option_value_length;
        struct option option;
        const guint32 padding = 0;

        if (option_value == NULL)
                return TRUE; /* nothing to write */
        option_value_length = strlen(option_value);
        if ((option_value_length > 0) && (option_value_length < G_MAXUINT16)) {
                /* something to write */
                option.type = option_type;
                option.value_length = (guint16)option_value_length;

                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)option_value, (int) option_value_length, bytes_written, err))
                        return FALSE;

                if (option_value_length % 4) {
                        if (!write_to_file(pfile, (const guint8*)&padding, 4 - option_value_length % 4, bytes_written, err))
                                return FALSE;
                }
        }
        return TRUE;
}

gboolean
pcapng_write_session_header_block(FILE* pfile,
                                  const char *comment,
                                  const char *hw,
                                  const char *os,
                                  const char *appname,
                                  guint64 section_length,
                                  guint64 *bytes_written,
                                  int *err)
{
        struct shb shb;
        struct option option;
        guint32 block_total_length;
        guint32 options_length;

        /* Size of base header */
        block_total_length = sizeof(struct shb) +
                             sizeof(guint32);
        options_length = 0;
        options_length += pcapng_count_string_option(comment);
        options_length += pcapng_count_string_option(hw);
        options_length += pcapng_count_string_option(os);
        options_length += pcapng_count_string_option(appname);
        /* If we have options add size of end-of-options */
        if (options_length != 0) {
                options_length += (guint32)sizeof(struct option);
        }
        block_total_length += options_length;

        /* write shb header */
        shb.block_type = SECTION_HEADER_BLOCK_TYPE;
        shb.block_total_length = block_total_length;
        shb.byte_order_magic = PCAPNG_MAGIC;
        shb.major_version = PCAPNG_MAJOR_VERSION;
        shb.minor_version = PCAPNG_MINOR_VERSION;
        shb.section_length = section_length;

        if (!write_to_file(pfile, (const guint8*)&shb, sizeof(struct shb), bytes_written, err))
                return FALSE;

        if (!pcapng_write_string_option(pfile, OPT_COMMENT, comment,
                                        bytes_written, err))
                return FALSE;
        if (!pcapng_write_string_option(pfile, SHB_HARDWARE, hw,
                                        bytes_written, err))
                return FALSE;
        if (!pcapng_write_string_option(pfile, SHB_OS, os,
                                        bytes_written, err))
                return FALSE;
        if (!pcapng_write_string_option(pfile, SHB_USERAPPL, appname,
                                        bytes_written, err))
                return FALSE;
        if (options_length != 0) {
                /* write end of options */
                option.type = OPT_ENDOFOPT;
                option.value_length = 0;
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;
        }

        /* write the trailing block total length */
        return write_to_file(pfile, (const guint8*)&block_total_length, sizeof(guint32), bytes_written, err);
}

gboolean
pcapng_write_interface_description_block(FILE* pfile,
                                         const char *comment, /* OPT_COMMENT        1 */
                                         const char *name,    /* IDB_NAME           2 */
                                         const char *descr,   /* IDB_DESCRIPTION    3 */
                                         const char *filter,  /* IDB_FILTER        11 */
                                         const char *os,      /* IDB_OS            12 */
                                         int link_type,
                                         int snap_len,
                                         guint64 *bytes_written,
                                         guint64 if_speed,    /* IDB_IF_SPEED       8 */
                                         guint8 tsresol,      /* IDB_TSRESOL        9 */
                                         int *err)
{
        struct idb idb;
        struct option option;
        guint32 block_total_length;
        guint32 options_length;
        const guint32 padding = 0;

        block_total_length = (guint32)(sizeof(struct idb) + sizeof(guint32));
        options_length = 0;
        /* 01 - OPT_COMMENT */
        options_length += pcapng_count_string_option(comment);

        /* 02 - IDB_NAME */
        options_length += pcapng_count_string_option(name);

        /* 03 - IDB_DESCRIPTION */
        options_length += pcapng_count_string_option(descr);

        /* 08 - IDB_IF_SPEED */
        if (if_speed != 0) {
                options_length += (guint32)(sizeof(struct option) +
                                            sizeof(guint64));
        }

        /* 09 - IDB_TSRESOL */
        if (tsresol != 0) {
                options_length += (guint32)(sizeof(struct option) +
                                            sizeof(struct option));
        }

        /* 11 - IDB_FILTER */
        if ((filter != NULL) && (strlen(filter) > 0) && (strlen(filter) < G_MAXUINT16)) {
                /* No, this isn't a string, it has an extra type byte */
                options_length += (guint32)(sizeof(struct option) +
                                            (guint16)(ADD_PADDING(strlen(filter)+ 1)));
        }

        /* 12 - IDB_OS */
        options_length += pcapng_count_string_option(os);

        /* If we have options add size of end-of-options */
        if (options_length != 0) {
                options_length += (guint32)sizeof(struct option);
        }
        block_total_length += options_length;

        /* write block header */
        idb.block_type = INTERFACE_DESCRIPTION_BLOCK_TYPE;
        idb.block_total_length = block_total_length;
        idb.link_type = link_type;
        idb.reserved = 0;
        idb.snap_len = snap_len;
        if (!write_to_file(pfile, (const guint8*)&idb, sizeof(struct idb), bytes_written, err))
                return FALSE;

        /* 01 - OPT_COMMENT - write comment string if applicable */
        if (!pcapng_write_string_option(pfile, OPT_COMMENT, comment,
                                        bytes_written, err))
                return FALSE;

        /* 02 - IDB_NAME - write interface name string if applicable */
        if (!pcapng_write_string_option(pfile, IDB_NAME, name,
                                        bytes_written, err))
                return FALSE;

        /* 03 - IDB_DESCRIPTION */
        /* write interface description string if applicable */
        if (!pcapng_write_string_option(pfile, IDB_DESCRIPTION, descr,
                                        bytes_written, err))
                return FALSE;

        /* 08 - IDB_IF_SPEED */
        if (if_speed != 0) {
                option.type = IDB_IF_SPEED;
                option.value_length = sizeof(guint64);

                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&if_speed, sizeof(guint64), bytes_written, err))
                        return FALSE;
        }

        /* 09 - IDB_TSRESOL */
        if (tsresol != 0) {
                option.type = IDB_TSRESOL;
                option.value_length = sizeof(guint8);

                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&tsresol, sizeof(guint8), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&padding, 3, bytes_written, err))
                        return FALSE;
        }

        /* 11 - IDB_FILTER - write filter string if applicable
         * We only write version 1 of the filter, pcapng string
         */
        if ((filter != NULL) && (strlen(filter) > 0) && (strlen(filter) < G_MAXUINT16 - 1)) {
                option.type = IDB_FILTER;
                option.value_length = (guint16)(strlen(filter) + 1 );
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                /* The first byte of the Option Data keeps a code of the filter used, 0 = lipbpcap filter string */
                if (!write_to_file(pfile, (const guint8*)&padding, 1, bytes_written, err))
                        return FALSE;
                if (!write_to_file(pfile, (const guint8*)filter, (int) strlen(filter), bytes_written, err))
                        return FALSE;
                if ((strlen(filter) + 1) % 4) {
                        if (!write_to_file(pfile, (const guint8*)&padding, 4 - (strlen(filter) + 1) % 4, bytes_written, err))
                                return FALSE;
                }
        }

        /* 12 - IDB_OS - write os string if applicable */
        if (!pcapng_write_string_option(pfile, IDB_OS, os,
                                        bytes_written, err))
                return FALSE;

        if (options_length != 0) {
                /* write end of options */
                option.type = OPT_ENDOFOPT;
                option.value_length = 0;
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;
        }

        /* write the trailing Block Total Length */
        return write_to_file(pfile, (const guint8*)&block_total_length, sizeof(guint32), bytes_written, err);
}

/* Write a record for a packet to a dump file.
   Returns TRUE on success, FALSE on failure. */
gboolean
pcapng_write_enhanced_packet_block(FILE* pfile,
                                   const char *comment,
                                   time_t sec, guint32 usec,
                                   guint32 caplen, guint32 len,
                                   guint32 interface_id,
                                   guint ts_mul,
                                   const guint8 *pd,
                                   guint32 flags,
                                   guint64 *bytes_written,
                                   int *err)
{
        struct epb epb;
        struct option option;
        guint32 block_total_length;
        guint64 timestamp;
        guint32 options_length;
        const guint32 padding = 0;

        block_total_length = (guint32)(sizeof(struct epb) +
                                       ADD_PADDING(caplen) +
                                       sizeof(guint32));
        options_length = 0;
        options_length += pcapng_count_string_option(comment);
        if (flags != 0) {
                options_length += (guint32)(sizeof(struct option) +
                                            sizeof(guint32));
        }
        /* If we have options add size of end-of-options */
        if (options_length != 0) {
                options_length += (guint32)sizeof(struct option);
        }
        block_total_length += options_length;
        timestamp = (guint64)sec * ts_mul + (guint64)usec;
        epb.block_type = ENHANCED_PACKET_BLOCK_TYPE;
        epb.block_total_length = block_total_length;
        epb.interface_id = interface_id;
        epb.timestamp_high = (guint32)((timestamp>>32) & 0xffffffff);
        epb.timestamp_low = (guint32)(timestamp & 0xffffffff);
        epb.captured_len = caplen;
        epb.packet_len = len;
        if (!write_to_file(pfile, (const guint8*)&epb, sizeof(struct epb), bytes_written, err))
                return FALSE;
        if (!write_to_file(pfile, pd, caplen, bytes_written, err))
                return FALSE;
        if (caplen % 4) {
                if (!write_to_file(pfile, (const guint8*)&padding, 4 - caplen % 4, bytes_written, err))
                        return FALSE;
        }
        if (!pcapng_write_string_option(pfile, OPT_COMMENT, comment,
                                        bytes_written, err))
                return FALSE;
        if (flags != 0) {
                option.type = EPB_FLAGS;
                option.value_length = sizeof(guint32);
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;
                if (!write_to_file(pfile, (const guint8*)&flags, sizeof(guint32), bytes_written, err))
                        return FALSE;
        }
        if (options_length != 0) {
                /* write end of options */
                option.type = OPT_ENDOFOPT;
                option.value_length = 0;
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;
        }

       return write_to_file(pfile, (const guint8*)&block_total_length, sizeof(guint32), bytes_written, err);
}

gboolean
pcapng_write_interface_statistics_block(FILE* pfile,
                                        guint32 interface_id,
                                        guint64 *bytes_written,
                                        const char *comment,   /* OPT_COMMENT           1 */
                                        guint64 isb_starttime, /* ISB_STARTTIME         2 */
                                        guint64 isb_endtime,   /* ISB_ENDTIME           3 */
                                        guint64 isb_ifrecv,    /* ISB_IFRECV            4 */
                                        guint64 isb_ifdrop,    /* ISB_IFDROP            5 */
                                        int *err)
{
        struct isb isb;
#ifdef _WIN32
        FILETIME now;
#else
        struct timeval now;
#endif
        struct option option;
        guint32 block_total_length;
        guint32 options_length;
        guint64 timestamp;

#ifdef _WIN32
        /*
         * Current time, represented as 100-nanosecond intervals since
         * January 1, 1601, 00:00:00 UTC.
         *
         * I think DWORD might be signed, so cast both parts of "now"
         * to guint32 so that the sign bit doesn't get treated specially.
         *
         * Windows 8 provides GetSystemTimePreciseAsFileTime which we
         * might want to use instead.
         */
        GetSystemTimeAsFileTime(&now);
        timestamp = (((guint64)(guint32)now.dwHighDateTime) << 32) +
                    (guint32)now.dwLowDateTime;

        /*
         * Convert to same thing but as 1-microsecond, i.e. 1000-nanosecond,
         * intervals.
         */
        timestamp /= 10;

        /*
         * Subtract difference, in microseconds, between January 1, 1601
         * 00:00:00 UTC and January 1, 1970, 00:00:00 UTC.
         */
        timestamp -= G_GUINT64_CONSTANT(11644473600000000);
#else
        /*
         * Current time, represented as seconds and microseconds since
         * January 1, 1970, 00:00:00 UTC.
         */
        gettimeofday(&now, NULL);

        /*
         * Convert to delta in microseconds.
         */
        timestamp = (guint64)(now.tv_sec) * 1000000 +
                    (guint64)(now.tv_usec);
#endif
        block_total_length = (guint32)(sizeof(struct isb) + sizeof(guint32));
        options_length = 0;
        if (isb_ifrecv != G_MAXUINT64) {
                options_length += (guint32)(sizeof(struct option) +
                                            sizeof(guint64));
        }
        if (isb_ifdrop != G_MAXUINT64) {
                options_length += (guint32)(sizeof(struct option) +
                                            sizeof(guint64));
        }
        /* OPT_COMMENT */
        options_length += pcapng_count_string_option(comment);
        if (isb_starttime !=0) {
                options_length += (guint32)(sizeof(struct option) +
                                            sizeof(guint64)); /* ISB_STARTTIME */
        }
        if (isb_endtime !=0) {
                options_length += (guint32)(sizeof(struct option) +
                                            sizeof(guint64)); /* ISB_ENDTIME */
        }
        /* If we have options add size of end-of-options */
        if (options_length != 0) {
                options_length += (guint32)sizeof(struct option);
        }
        block_total_length += options_length;

        isb.block_type = INTERFACE_STATISTICS_BLOCK_TYPE;
        isb.block_total_length = block_total_length;
        isb.interface_id = interface_id;
        isb.timestamp_high = (guint32)((timestamp>>32) & 0xffffffff);
        isb.timestamp_low = (guint32)(timestamp & 0xffffffff);
        if (!write_to_file(pfile, (const guint8*)&isb, sizeof(struct isb), bytes_written, err))
                return FALSE;

        /* write comment string if applicable */
        if (!pcapng_write_string_option(pfile, OPT_COMMENT, comment,
                                        bytes_written, err))
                return FALSE;

        if (isb_starttime !=0) {
                guint32 high, low;

                option.type = ISB_STARTTIME;
                option.value_length = sizeof(guint64);
                high = (guint32)((isb_starttime>>32) & 0xffffffff);
                low = (guint32)(isb_starttime & 0xffffffff);
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&high, sizeof(guint32), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&low, sizeof(guint32), bytes_written, err))
                        return FALSE;
        }
        if (isb_endtime !=0) {
                guint32 high, low;

                option.type = ISB_ENDTIME;
                option.value_length = sizeof(guint64);
                high = (guint32)((isb_endtime>>32) & 0xffffffff);
                low = (guint32)(isb_endtime & 0xffffffff);
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&high, sizeof(guint32), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&low, sizeof(guint32), bytes_written, err))
                        return FALSE;
        }
        if (isb_ifrecv != G_MAXUINT64) {
                option.type = ISB_IFRECV;
                option.value_length = sizeof(guint64);
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&isb_ifrecv, sizeof(guint64), bytes_written, err))
                        return FALSE;
        }
        if (isb_ifdrop != G_MAXUINT64) {
                option.type = ISB_IFDROP;
                option.value_length = sizeof(guint64);
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;

                if (!write_to_file(pfile, (const guint8*)&isb_ifdrop, sizeof(guint64), bytes_written, err))
                        return FALSE;
        }
        if (options_length != 0) {
                /* write end of options */
                option.type = OPT_ENDOFOPT;
                option.value_length = 0;
                if (!write_to_file(pfile, (const guint8*)&option, sizeof(struct option), bytes_written, err))
                        return FALSE;
        }

        return write_to_file(pfile, (const guint8*)&block_total_length, sizeof(guint32), bytes_written, err);
}

/*
 * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */