aboutsummaryrefslogtreecommitdiffstats
path: root/capture.c
blob: b200de889c955a20969554ca073903d892f25b11 (plain)
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
/* capture.c
 * Routines for packet capture windows
 *
 * $Id$
 *
 * Ethereal - Network traffic analyzer
 * By Gerald Combs <gerald@ethereal.com>
 * Copyright 1998 Gerald Combs
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

/* With MSVC and a libethereal.dll this file needs to import some variables 
   in a special way. Therefore _NEED_VAR_IMPORT_ is defined. */
#define _NEED_VAR_IMPORT_

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_LIBPCAP

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

#ifdef HAVE_IO_H
# include <io.h>
#endif

#include <signal.h>
#include <errno.h>

#include <pcap.h>

#include <glib.h>

#include <epan/packet.h>
#include <epan/dfilter/dfilter.h>
#include "file.h"
#include "capture.h"
#include "capture_sync.h"
#include "capture_ui_utils.h"
#include "util.h"
#include "pcap-util.h"
#include "alert_box.h"
#include "simple_dialog.h"
#include <epan/prefs.h>
#include "conditions.h"
#include "ringbuffer.h"

#ifdef _WIN32
#include "capture-wpcap.h"
#endif
#include "ui_util.h"


/* Win32 needs the O_BINARY flag for open() */
#ifndef O_BINARY
#define O_BINARY	0
#endif

static gboolean normal_do_capture(capture_options *capture_opts, gboolean is_tempfile);
static void stop_capture_signal_handler(int signo);


void
capture_opts_init(capture_options *capture_opts, void *cfile)
{
  capture_opts->cf                      = cfile;
  capture_opts->cfilter		            = g_strdup("");
  capture_opts->iface                   = NULL;
#ifdef _WIN32
  capture_opts->buffer_size             = 1;                /* 1 MB */
#endif
  capture_opts->has_snaplen             = FALSE;
  capture_opts->snaplen                 = MIN_PACKET_SIZE;
  capture_opts->promisc_mode            = TRUE;
  capture_opts->linktype                = -1;               /* the default linktype */
  capture_opts->capture_child           = FALSE;
  capture_opts->save_file               = NULL;
  capture_opts->save_file_fd            = -1;
  capture_opts->sync_mode               = TRUE;
  capture_opts->show_info               = TRUE;
  capture_opts->quit_after_cap          = FALSE;

  capture_opts->multi_files_on          = FALSE;
  capture_opts->has_file_duration       = FALSE;
  capture_opts->file_duration           = 60;               /* 1 min */
  capture_opts->has_ring_num_files      = TRUE;
  capture_opts->ring_num_files          = 2;

  capture_opts->has_autostop_files      = FALSE;
  capture_opts->autostop_files          = 1;
  capture_opts->has_autostop_packets    = FALSE;
  capture_opts->autostop_packets        = 1;
  capture_opts->has_autostop_filesize   = FALSE;
  capture_opts->autostop_filesize       = 1024 * 1024;      /* 1 MB */
  capture_opts->has_autostop_duration   = FALSE;
  capture_opts->autostop_duration       = 60;               /* 1 min */

}

static int
get_natural_int(const char *string, const char *name)
{
  long number;
  char *p;

  number = strtol(string, &p, 10);
  if (p == string || *p != '\0') {
    fprintf(stderr, "ethereal: The specified %s \"%s\" isn't a decimal number\n",
	    name, string);
    exit(1);
  }
  if (number < 0) {
    fprintf(stderr, "ethereal: The specified %s \"%s\" is a negative number\n",
	    name, string);
    exit(1);
  }
  if (number > INT_MAX) {
    fprintf(stderr, "ethereal: The specified %s \"%s\" is too large (greater than %d)\n",
	    name, string, INT_MAX);
    exit(1);
  }
  return number;
}


static int
get_positive_int(const char *string, const char *name)
{
  long number;

  number = get_natural_int(string, name);

  if (number == 0) {
    fprintf(stderr, "ethereal: The specified %s is zero\n",
	    name);
    exit(1);
  }

  return number;
}


/*
 * Given a string of the form "<autostop criterion>:<value>", as might appear
 * as an argument to a "-a" option, parse it and set the criterion in
 * question.  Return an indication of whether it succeeded or failed
 * in some fashion.
 */
static gboolean
set_autostop_criterion(capture_options *capture_opts, const char *autostoparg)
{
  gchar *p, *colonp;

  colonp = strchr(autostoparg, ':');
  if (colonp == NULL)
    return FALSE;

  p = colonp;
  *p++ = '\0';

  /*
   * Skip over any white space (there probably won't be any, but
   * as we allow it in the preferences file, we might as well
   * allow it here).
   */
  while (isspace((guchar)*p))
    p++;
  if (*p == '\0') {
    /*
     * Put the colon back, so if our caller uses, in an
     * error message, the string they passed us, the message
     * looks correct.
     */
    *colonp = ':';
    return FALSE;
  }
  if (strcmp(autostoparg,"duration") == 0) {
    capture_opts->has_autostop_duration = TRUE;
    capture_opts->autostop_duration = get_positive_int(p,"autostop duration");
  } else if (strcmp(autostoparg,"filesize") == 0) {
    capture_opts->has_autostop_filesize = TRUE;
    capture_opts->autostop_filesize = get_positive_int(p,"autostop filesize");
  } else {
    return FALSE;
  }
  *colonp = ':'; /* put the colon back */
  return TRUE;
}

/*
 * Given a string of the form "<ring buffer file>:<duration>", as might appear
 * as an argument to a "-b" option, parse it and set the arguments in
 * question.  Return an indication of whether it succeeded or failed
 * in some fashion.
 */
static gboolean
get_ring_arguments(capture_options *capture_opts, const char *arg)
{
  gchar *p = NULL, *colonp;

  colonp = strchr(arg, ':');

  if (colonp != NULL) {
    p = colonp;
    *p++ = '\0';
  }

  capture_opts->ring_num_files = 
    get_natural_int(arg, "number of ring buffer files");

  if (colonp == NULL)
    return TRUE;

  /*
   * Skip over any white space (there probably won't be any, but
   * as we allow it in the preferences file, we might as well
   * allow it here).
   */
  while (isspace((guchar)*p))
    p++;
  if (*p == '\0') {
    /*
     * Put the colon back, so if our caller uses, in an
     * error message, the string they passed us, the message
     * looks correct.
     */
    *colonp = ':';
    return FALSE;
  }

  capture_opts->has_file_duration = TRUE;
  capture_opts->file_duration = get_positive_int(p,
						      "ring buffer duration");

  *colonp = ':';	/* put the colon back */
  return TRUE;
}


void
capture_opt_add(capture_options *capture_opts, int opt, const char *optarg, gboolean *start_capture)
{
#ifdef _WIN32
    int i;
#endif

    switch(opt) {
    case 'a':        /* autostop criteria */
        if (set_autostop_criterion(capture_opts, optarg) == FALSE) {
          fprintf(stderr, "ethereal: Invalid or unknown -a flag \"%s\"\n", optarg);
          exit(1);
        }
        break;
    case 'b':        /* Ringbuffer option */
        capture_opts->multi_files_on = TRUE;
        capture_opts->has_ring_num_files = TRUE;
        if (get_ring_arguments(capture_opts, optarg) == FALSE) {
          fprintf(stderr, "ethereal: Invalid or unknown -b arg \"%s\"\n", optarg);
          exit(1);
        }
        break;
    case 'c':        /* Capture xxx packets */
        capture_opts->has_autostop_packets = TRUE;
        capture_opts->autostop_packets = get_positive_int(optarg, "packet count");
        break;
    case 'f':        /* capture filter */
        if (capture_opts->cfilter)
            g_free(capture_opts->cfilter);
        capture_opts->cfilter = g_strdup(optarg);
        break;
    case 'H':        /* Hide capture info dialog box */
        capture_opts->show_info = FALSE;
        break;
    case 'i':        /* Use interface xxx */
        capture_opts->iface = g_strdup(optarg);
        break;
    case 'k':        /* Start capture immediately */
        *start_capture = TRUE;
        break;
    /*case 'l':*/    /* Automatic scrolling in live capture mode */
    case 'p':        /* Don't capture in promiscuous mode */
        capture_opts->promisc_mode = FALSE;
        break;
    case 'Q':        /* Quit after capture (just capture to file) */
        capture_opts->quit_after_cap  = TRUE;
        *start_capture   = TRUE;  /*** -Q implies -k !! ***/
        break;
    case 's':        /* Set the snapshot (capture) length */
        capture_opts->has_snaplen = TRUE;
        capture_opts->snaplen = get_positive_int(optarg, "snapshot length");
        break;
    case 'S':        /* "Sync" mode: used for following file ala tail -f */
        capture_opts->sync_mode = TRUE;
        break;
    case 'w':        /* Write to capture file xxx */
        capture_opts->save_file = g_strdup(optarg);
	    break;
    case 'W':        /* Write to capture file FD xxx */
        capture_opts->save_file_fd = atoi(optarg);
        break;
    case 'y':        /* Set the pcap data link type */
#ifdef HAVE_PCAP_DATALINK_NAME_TO_VAL
        capture_opts->linktype = pcap_datalink_name_to_val(optarg);
        if (capture_opts->linktype == -1) {
          fprintf(stderr, "ethereal: The specified data link type \"%s\" isn't valid\n",
                  optarg);
          exit(1);
        }
#else /* HAVE_PCAP_DATALINK_NAME_TO_VAL */
        /* XXX - just treat it as a number */
        capture_opts->linktype = get_natural_int(optarg, "data link type");
#endif /* HAVE_PCAP_DATALINK_NAME_TO_VAL */
        break;
#ifdef _WIN32
      /* Hidden option supporting Sync mode */
    case 'Z':        /* Write to pipe FD XXX */
        /* associate stdout with pipe */
        i = atoi(optarg);
        if (dup2(i, 1) < 0) {
          fprintf(stderr, "Unable to dup pipe handle\n");
          exit(1);
        }
        break;
#endif /* _WIN32 */
    default:
        /* the caller is responsible to send us only the right opt's */
        g_assert_not_reached();
    }
}

/* open the output file (temporary/specified name/ringbuffer) and close the old one */
/* Returns TRUE if the file opened successfully, FALSE otherwise. */
static gboolean
capture_open_output(capture_options *capture_opts, gboolean *is_tempfile) {
  char tmpname[128+1];
  gchar *capfile_name;


  if (capture_opts->save_file != NULL) {
    /* If the Sync option is set, we return to the caller while the capture
     * is in progress.  Therefore we need to take a copy of save_file in
     * case the caller destroys it after we return.
     */
    capfile_name = g_strdup(capture_opts->save_file);
    if (capture_opts->multi_files_on) {
      /* ringbuffer is enabled */
      capture_opts->save_file_fd = ringbuf_init(capfile_name,
          (capture_opts->has_ring_num_files) ? capture_opts->ring_num_files : 0);
    } else {
      /* Try to open/create the specified file for use as a capture buffer. */
      capture_opts->save_file_fd = open(capfile_name, O_RDWR|O_BINARY|O_TRUNC|O_CREAT,
				0600);
    }
    *is_tempfile = FALSE;
  } else {
    /* Choose a random name for the temporary capture buffer */
    capture_opts->save_file_fd = create_tempfile(tmpname, sizeof tmpname, "ether");
    capfile_name = g_strdup(tmpname);
    *is_tempfile = TRUE;
  }

  /* did we fail to open the output file? */
  if (capture_opts->save_file_fd == -1) {
    if (is_tempfile) {
      simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK,
	"The temporary file to which the capture would be saved (\"%s\")"
	"could not be opened: %s.", capfile_name, strerror(errno));
    } else {
      if (capture_opts->multi_files_on) {
        ringbuf_error_cleanup();
      }
      open_failure_alert_box(capfile_name, errno, TRUE);
    }
    g_free(capfile_name);
    return FALSE;
  }

  /* close the old file */
  cf_close(capture_opts->cf);
  if(capture_opts->save_file != NULL) {
    g_free(capture_opts->save_file);
  }
  capture_opts->save_file = capfile_name;
  /* capture_opts.save_file is "g_free"ed later, which is equivalent to
     "g_free(capfile_name)". */

  return TRUE;
}


/* Open a specified file, or create a temporary file, and start a capture
   to the file in question.  */
/* Returns TRUE if the capture starts successfully, FALSE otherwise. */
gboolean
do_capture(capture_options *capture_opts)
{
  gboolean is_tempfile;
  gboolean ret;

  /* open the output file (temporary/specified name/ringbuffer) and close the old one */
  if(!capture_open_output(capture_opts, &is_tempfile)) {
    return FALSE;
  }

  if (capture_opts->sync_mode) {	
    /* sync mode: do the capture in a child process */
    ret = sync_pipe_do_capture(capture_opts, is_tempfile);
    /* capture is still running */
    cf_callback_invoke(cf_cb_live_capture_started, capture_opts);
  } else {
    /* normal mode: do the capture synchronously */
    cf_callback_invoke(cf_cb_live_capture_started, capture_opts);
    ret = normal_do_capture(capture_opts, is_tempfile);
    /* capture is finished here */
  }

  return ret;
}


/* start a normal capture session */
static gboolean
normal_do_capture(capture_options *capture_opts, gboolean is_tempfile)
{
    int capture_succeeded;
    gboolean stats_known;
    struct pcap_stat stats;
    int err;

    /* Not sync mode. */
    capture_succeeded = capture_start(capture_opts, &stats_known, &stats);
    if (capture_opts->quit_after_cap) {
      /* DON'T unlink the save file.  Presumably someone wants it. */
        main_window_exit();
    }
    if (!capture_succeeded) {
      /* We didn't succeed in doing the capture, so we don't have a save
	 file. */
      if (capture_opts->multi_files_on) {
	ringbuf_free();
      } else {
	g_free(capture_opts->save_file);
      }
      capture_opts->save_file = NULL;
      return FALSE;
    }
    /* Capture succeeded; attempt to read in the capture file. */
    if (cf_open(capture_opts->cf, capture_opts->save_file, is_tempfile, &err) != CF_OK) {
      /* We're not doing a capture any more, so we don't have a save
	 file. */
      if (capture_opts->multi_files_on) {
	ringbuf_free();
      } else {
	g_free(capture_opts->save_file);
      }
      capture_opts->save_file = NULL;
      return FALSE;
    }

    /* Set the read filter to NULL. */
    cf_set_rfcode(capture_opts->cf, NULL);

    /* Get the packet-drop statistics.

       XXX - there are currently no packet-drop statistics stored
       in libpcap captures, and that's what we're reading.

       At some point, we will add support in Wiretap to return
       packet-drop statistics for capture file formats that store it,
       and will make "cf_read()" get those statistics from Wiretap.
       We clear the statistics (marking them as "not known") in
       "cf_open()", and "cf_read()" will only fetch them and mark
       them as known if Wiretap supplies them, so if we get the
       statistics now, after calling "cf_open()" but before calling
       "cf_read()", the values we store will be used by "cf_read()".

       If a future libpcap capture file format stores the statistics,
       we'll put them into the capture file that we write, and will
       thus not have to set them here - "cf_read()" will get them from
       the file and use them. */
    if (stats_known) {
      cf_set_drops_known(capture_opts->cf, TRUE);

      /* XXX - on some systems, libpcap doesn't bother filling in
         "ps_ifdrop" - it doesn't even set it to zero - so we don't
         bother looking at it.

         Ideally, libpcap would have an interface that gave us
         several statistics - perhaps including various interface
         error statistics - and would tell us which of them it
         supplies, allowing us to display only the ones it does. */
      cf_set_drops(capture_opts->cf, stats.ps_drop);
    }
    switch (cf_read(capture_opts->cf)) {

    case CF_READ_OK:
    case CF_READ_ERROR:
      /* Just because we got an error, that doesn't mean we were unable
         to read any of the file; we handle what we could get from the
         file. */
      break;

    case CF_READ_ABORTED:
      /* Exit by leaving the main loop, so that any quit functions
         we registered get called. */
      main_window_nested_quit();
      return FALSE;
    }

    /* We're not doing a capture any more, so we don't have a save
       file. */
    if (capture_opts->multi_files_on) {
      ringbuf_free();
    } else {
      g_free(capture_opts->save_file);
    }
    capture_opts->save_file = NULL;

    /* if we didn't captured even a single packet, close the file again */
    if(cf_packet_count(capture_opts->cf) == 0) {
      simple_dialog(ESD_TYPE_INFO, ESD_BTN_OK, 
      "%sNo packets captured!%s\n\n"
      "As no data was captured, closing the %scapture file!",
      simple_dialog_primary_start(), simple_dialog_primary_end(),
      (cf_is_tempfile(capture_opts->cf)) ? "temporary " : "");
      cf_close(capture_opts->cf);
    }
  return TRUE;
}


static void
stop_capture_signal_handler(int signo _U_)
{
  capture_loop_stop();
}


int  
capture_start(capture_options *capture_opts, gboolean *stats_known, struct pcap_stat *stats)
{
#ifndef _WIN32
  /*
   * Catch SIGUSR1, so that we exit cleanly if the parent process
   * kills us with it due to the user selecting "Capture->Stop".
   */
  if (capture_opts->capture_child)
    signal(SIGUSR1, stop_capture_signal_handler);
#endif

  return capture_loop_start(capture_opts, stats_known, stats);
}

void
capture_stop(capture_options *capture_opts)
{

  if (capture_opts->sync_mode) {	
    sync_pipe_stop(capture_opts);
  }
    
  capture_loop_stop();
}

void
capture_kill_child(capture_options *capture_opts)
{
  if (capture_opts->sync_mode) {	
    sync_pipe_kill(capture_opts);
  }
}


#endif /* HAVE_LIBPCAP */