aboutsummaryrefslogtreecommitdiffstats
path: root/epan/follow.c
blob: 8900d7101c5cf414103ca76cf4cc67ce5717e38f (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
595
596
597
598
599
600
601
602
603
604
605
/* follow.c
 *
 * Copyright 1998 Mike Hall <mlh@io.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <glib.h>
#include <epan/packet.h>
#include <epan/to_str.h>
#include <epan/dissectors/packet-tcp.h>
#include <epan/dissectors/packet-udp.h>
#include "follow.h"
#include <epan/conversation.h>
#include <epan/tap.h>

#define MAX_IPADDR_LEN  16

typedef struct _tcp_frag {
  guint32             seq;
  guint32             len;
  guint32             data_len;
  gchar              *data;
  struct _tcp_frag   *next;
} tcp_frag;

WS_DLL_PUBLIC_DEF
FILE* data_out_file = NULL;

gboolean empty_tcp_stream;
gboolean incomplete_tcp_stream;

static guint32 stream_to_follow[MAX_STREAM] = {0};
static gboolean find_addr[MAX_STREAM] = {FALSE};
static gboolean find_index[MAX_STREAM] = {FALSE};
static address tcp_addr[2];
static guint8  ip_address[2][MAX_IPADDR_LEN];
static guint   port[2];
static guint   bytes_written[2];
static gboolean is_ipv6 = FALSE;

static int check_fragments( int, tcp_stream_chunk *, guint32 );
static void write_packet_data( int, tcp_stream_chunk *, const char * );

void
follow_stats(follow_stats_t* stats)
{
  int i;

  for (i = 0; i < 2 ; i++) {
    memcpy(stats->ip_address[i], ip_address[i], MAX_IPADDR_LEN);
    stats->port[i] = port[i];
    stats->bytes_written[i] = bytes_written[i];
    stats->is_ipv6 = is_ipv6;
  }
}

/* This will build a display filter text that will only
   pass the packets related to the stream. There is a
   chance that two streams could intersect, but not a
   very good one */
gchar*
build_follow_conv_filter( packet_info *pi ) {
  char* buf;
  int len;
  conversation_t *conv=NULL;
  struct tcp_analysis *tcpd;
  struct udp_analysis *udpd;
  wmem_list_frame_t* protos;
  int proto_id;
  const char* proto_name;
  gboolean is_tcp = FALSE, is_udp = FALSE;

  protos = wmem_list_head(pi->layers);

  /* walk the list of a available protocols in the packet to
      figure out if any of them affect context sensitivity */
  while (protos != NULL)
  {
    proto_id = GPOINTER_TO_INT(wmem_list_frame_data(protos));
    proto_name = proto_get_protocol_filter_name(proto_id);

    if (!strcmp(proto_name, "tcp")) {
        is_tcp = TRUE;
    } else if (!strcmp(proto_name, "udp")) {
        is_udp = TRUE;
    }

    protos = wmem_list_frame_next(protos);
  }

  if( ((pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4) ||
       (pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6))
       && is_tcp && (conv=find_conversation(pi->fd->num, &pi->src, &pi->dst, pi->ptype,
              pi->srcport, pi->destport, 0)) != NULL ) {
    /* TCP over IPv4/6 */
    tcpd=get_tcp_conversation_data(conv, pi);
    if (tcpd) {
      buf = g_strdup_printf("tcp.stream eq %d", tcpd->stream);
      stream_to_follow[TCP_STREAM] = tcpd->stream;
      if (pi->net_src.type == AT_IPv4) {
        len = 4;
        is_ipv6 = FALSE;
      } else {
        len = 16;
        is_ipv6 = TRUE;
      }
    } else {
      return NULL;
    }
  }
  else if( ((pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4) ||
            (pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6))
          && is_udp && (conv=find_conversation(pi->fd->num, &pi->src, &pi->dst, pi->ptype,
              pi->srcport, pi->destport, 0)) != NULL ) {
    /* UDP over IPv4/6 */
    udpd=get_udp_conversation_data(conv, pi);
    if (udpd) {
      buf = g_strdup_printf("udp.stream eq %d", udpd->stream);
      stream_to_follow[UDP_STREAM] = udpd->stream;
      if (pi->net_src.type == AT_IPv4) {
        len = 4;
        is_ipv6 = FALSE;
      } else {
        len = 16;
        is_ipv6 = TRUE;
      }
    } else {
      return NULL;
    }
  }
  else {
    return NULL;
  }
  memcpy(ip_address[0], pi->net_src.data, len);
  memcpy(ip_address[1], pi->net_dst.data, len);
  port[0] = pi->srcport;
  port[1] = pi->destport;
  return buf;
}

static gboolean
udp_follow_packet(void *tapdata _U_, packet_info *pinfo,
                  epan_dissect_t *edt _U_, const void *data _U_)
{
  if (find_addr[UDP_STREAM]) {
    if (pinfo->net_src.type == AT_IPv6) {
      is_ipv6 = TRUE;
    } else {
      is_ipv6 = FALSE;
    }
    memcpy(ip_address[0], pinfo->net_src.data, pinfo->net_src.len);
    memcpy(ip_address[1], pinfo->net_dst.data, pinfo->net_dst.len);
    port[0] = pinfo->srcport;
    port[1] = pinfo->destport;
    find_addr[UDP_STREAM] = FALSE;
  }

  return FALSE;
}

void
reset_udp_follow(void) {
  remove_tap_listener(&stream_to_follow[UDP_STREAM]);
  find_addr[UDP_STREAM] = FALSE;
  find_addr[UDP_STREAM] = FALSE;
}

gchar*
build_follow_index_filter(stream_type stream) {
  gchar *buf;

  find_addr[stream] = TRUE;
  if (stream == TCP_STREAM) {
    buf = g_strdup_printf("tcp.stream eq %d", stream_to_follow[TCP_STREAM]);
  } else {
    GString * error_string;
    buf = g_strdup_printf("udp.stream eq %d", stream_to_follow[UDP_STREAM]);
    error_string = register_tap_listener("udp_follow", &stream_to_follow[UDP_STREAM], buf, 0, NULL, udp_follow_packet, NULL);
    if (error_string) {
      g_string_free(error_string, TRUE);
    }
  }
  return buf;
}

/* select a tcp stream to follow via it's address/port pairs */
gboolean
follow_addr(stream_type stream, const address *addr0, guint port0,
            const address *addr1, guint port1)
{
  if (addr0 == NULL || addr1 == NULL || addr0->type != addr1->type ||
      port0 > G_MAXUINT16 || port1 > G_MAXUINT16 )  {
    return FALSE;
  }

  if (find_index[stream] || find_addr[stream]) {
    return FALSE;
  }

  switch (addr0->type) {
  default:
    return FALSE;
  case AT_IPv4:
  case AT_IPv6:
    is_ipv6 = addr0->type == AT_IPv6;
    break;
  }


  memcpy(ip_address[0], addr0->data, addr0->len);
  port[0] = port0;

  memcpy(ip_address[1], addr1->data, addr1->len);
  port[1] = port1;

  if (stream == TCP_STREAM) {
    find_index[TCP_STREAM] = TRUE;
    SET_ADDRESS(&tcp_addr[0], addr0->type, addr0->len, ip_address[0]);
    SET_ADDRESS(&tcp_addr[1], addr1->type, addr1->len, ip_address[1]);
  }

  return TRUE;
}

/* select a stream to follow via its index */
gboolean
follow_index(stream_type stream, guint32 indx)
{
  if (find_index[stream] || find_addr[stream]) {
    return FALSE;
  }

  find_addr[stream] = TRUE;
  stream_to_follow[stream] = indx;
  memset(ip_address, 0, sizeof ip_address);
  port[0] = port[1] = 0;

  return TRUE;
}

guint32
get_follow_index(stream_type stream) {
  return stream_to_follow[stream];
}

/* here we are going to try and reconstruct the data portion of a TCP
   session. We will try and handle duplicates, TCP fragments, and out
   of order packets in a smart way. */

static tcp_frag *frags[2] = { 0, 0 };
static guint32 seq[2];
static guint8 src_addr[2][MAX_IPADDR_LEN];
static guint src_port[2] = { 0, 0 };

void
reassemble_tcp( guint32 tcp_stream, guint32 sequence, guint32 acknowledgement,
                guint32 length, const char* data, guint32 data_length,
                int synflag, address *net_src, address *net_dst,
                guint srcport, guint dstport, guint32 packet_num) {
  guint8 srcx[MAX_IPADDR_LEN], dstx[MAX_IPADDR_LEN];
  int src_index, j, first = 0, len;
  guint32 newseq;
  tcp_frag *tmp_frag;
  tcp_stream_chunk sc;

  src_index = -1;

  /* First, check if this packet should be processed. */
  if (find_index[TCP_STREAM]) {
    if ((port[0] == srcport && port[1] == dstport &&
         ADDRESSES_EQUAL(&tcp_addr[0], net_src) &&
         ADDRESSES_EQUAL(&tcp_addr[1], net_dst))
        ||
        (port[1] == srcport && port[0] == dstport &&
         ADDRESSES_EQUAL(&tcp_addr[1], net_src) &&
         ADDRESSES_EQUAL(&tcp_addr[0], net_dst))) {
      find_index[TCP_STREAM] = FALSE;
      stream_to_follow[TCP_STREAM] = tcp_stream;
    }
    else {
      return;
    }
  }
  else if ( tcp_stream != stream_to_follow[TCP_STREAM] )
    return;

  if ((net_src->type != AT_IPv4 && net_src->type != AT_IPv6) ||
      (net_dst->type != AT_IPv4 && net_dst->type != AT_IPv6))
    return;

  if (net_src->type == AT_IPv4)
    len = 4;
  else
    len = 16;

  memcpy(srcx, net_src->data, len);
  memcpy(dstx, net_dst->data, len);

  /* follow_tcp_index() needs to learn address/port pairs */
  if (find_addr[TCP_STREAM]) {
    find_addr[TCP_STREAM] = FALSE;
    memcpy(ip_address[0], net_src->data, net_src->len);
    port[0] = srcport;
    memcpy(ip_address[1], net_dst->data, net_dst->len);
    port[1] = dstport;
    if (net_src->type == AT_IPv6 && net_dst->type == AT_IPv6) {
      is_ipv6 = TRUE;
    } else {
      is_ipv6 = FALSE;
    }
  }

  /* Check to see if we have seen this source IP and port before.
     (Yes, we have to check both source IP and port; the connection
     might be between two different ports on the same machine.) */
  for( j=0; j<2; j++ ) {
    if (memcmp(src_addr[j], srcx, len) == 0 && src_port[j] == srcport ) {
      src_index = j;
    }
  }
  /* we didn't find it if src_index == -1 */
  if( src_index < 0 ) {
    /* assign it to a src_index and get going */
    for( j=0; j<2; j++ ) {
      if( src_port[j] == 0 ) {
        memcpy(src_addr[j], srcx, len);
        src_port[j] = srcport;
        src_index = j;
        first = 1;
        break;
      }
    }
  }
  if( src_index < 0 ) {
    fprintf( stderr, "ERROR in reassemble_tcp: Too many addresses!\n");
    return;
  }

  if( data_length < length ) {
    incomplete_tcp_stream = TRUE;
  }

  /* Before adding data for this flow to the data_out_file, check whether
   * this frame acks fragments that were already seen. This happens when
   * frames are not in the capture file, but were actually seen by the
   * receiving host (Fixes bug 592).
   */
  if( frags[1-src_index] ) {
    memcpy(sc.src_addr, dstx, len);
    sc.src_port = dstport;
    sc.dlen     = 0;        /* Will be filled in in check_fragments */
    while ( check_fragments( 1-src_index, &sc, acknowledgement ) )
      ;
  }

  /* Initialize our stream chunk.  This data gets written to disk. */
  memcpy(sc.src_addr, srcx, len);
  sc.src_port   = srcport;
  sc.dlen       = data_length;
  sc.packet_num = packet_num;

  /* now that we have filed away the srcs, lets get the sequence number stuff
     figured out */
  if( first ) {
    /* this is the first time we have seen this src's sequence number */
    seq[src_index] = sequence + length;
    if( synflag ) {
      seq[src_index]++;
    }
    /* write out the packet data */
    write_packet_data( src_index, &sc, data );
    return;
  }
  /* if we are here, we have already seen this src, let's
     try and figure out if this packet is in the right place */
  if( LT_SEQ(sequence, seq[src_index]) ) {
    /* this sequence number seems dated, but
       check the end to make sure it has no more
       info than we have already seen */
    newseq = sequence + length;
    if( GT_SEQ(newseq, seq[src_index]) ) {
      guint32 new_len;

      /* this one has more than we have seen. let's get the
         payload that we have not seen. */

      new_len = seq[src_index] - sequence;

      if ( data_length <= new_len ) {
        data = NULL;
        data_length = 0;
        incomplete_tcp_stream = TRUE;
      } else {
        data += new_len;
        data_length -= new_len;
      }
      sc.dlen = data_length;
      sequence = seq[src_index];
      length = newseq - seq[src_index];

      /* this will now appear to be right on time :) */
    }
  }
  if ( EQ_SEQ(sequence, seq[src_index]) ) {
    /* right on time */
    seq[src_index] += length;
    if( synflag ) seq[src_index]++;
    if( data ) {
      write_packet_data( src_index, &sc, data );
    }
    /* done with the packet, see if it caused a fragment to fit */
    while( check_fragments( src_index, &sc, 0 ) )
      ;
  }
  else {
    /* out of order packet */
    if(data_length > 0 && GT_SEQ(sequence, seq[src_index]) ) {
      tmp_frag = (tcp_frag *)g_malloc( sizeof( tcp_frag ) );
      tmp_frag->data = (gchar *)g_malloc( data_length );
      tmp_frag->seq = sequence;
      tmp_frag->len = length;
      tmp_frag->data_len = data_length;
      memcpy( tmp_frag->data, data, data_length );
      if( frags[src_index] ) {
        tmp_frag->next = frags[src_index];
      } else {
        tmp_frag->next = NULL;
      }
      frags[src_index] = tmp_frag;
    }
  }
} /* end reassemble_tcp */

/* here we search through all the frag we have collected to see if
   one fits */
static int
check_fragments( int idx, tcp_stream_chunk *sc, guint32 acknowledged ) {
  tcp_frag *prev = NULL;
  tcp_frag *current;
  guint32 lowest_seq;
  gchar *dummy_str;

  current = frags[idx];
  if( current ) {
    lowest_seq = current->seq;
    while( current ) {
      if( GT_SEQ(lowest_seq, current->seq) ) {
        lowest_seq = current->seq;
      }

      if( LT_SEQ(current->seq, seq[idx]) ) {
        guint32 newseq;
        /* this sequence number seems dated, but
           check the end to make sure it has no more
           info than we have already seen */
        newseq = current->seq + current->len;
        if( GT_SEQ(newseq, seq[idx]) ) {
          guint32 new_pos;

          /* this one has more than we have seen. let's get the
             payload that we have not seen. This happens when
             part of this frame has been retransmitted */

          new_pos = seq[idx] - current->seq;

          if ( current->data_len > new_pos ) {
            sc->dlen = current->data_len - new_pos;
            write_packet_data( idx, sc, current->data + new_pos );
          }

          seq[idx] += (current->len - new_pos);
        }

        /* Remove the fragment from the list as the "new" part of it
         * has been processed or its data has been seen already in
         * another packet. */
        if( prev ) {
          prev->next = current->next;
        } else {
          frags[idx] = current->next;
        }
        g_free( current->data );
        g_free( current );
        return 1;
      }

      if( EQ_SEQ(current->seq, seq[idx]) ) {
        /* this fragment fits the stream */
        if( current->data ) {
          sc->dlen = current->data_len;
          write_packet_data( idx, sc, current->data );
        }
        seq[idx] += current->len;
        if( prev ) {
          prev->next = current->next;
        } else {
          frags[idx] = current->next;
        }
        g_free( current->data );
        g_free( current );
        return 1;
      }
      prev = current;
      current = current->next;
    }
    if( GT_SEQ(acknowledged, lowest_seq) ) {
      /* There are frames missing in the capture file that were seen
       * by the receiving host. Add dummy stream chunk with the data
       * "[xxx bytes missing in capture file]".
       */
      dummy_str = g_strdup_printf("[%d bytes missing in capture file]",
                        (int)(lowest_seq - seq[idx]) );
      sc->dlen = (guint32) strlen(dummy_str);
      write_packet_data( idx, sc, dummy_str );
      g_free(dummy_str);
      seq[idx] = lowest_seq;
      return 1;
    }
  }
  return 0;
}

/* this should always be called before we start to reassemble a stream */
void
reset_tcp_reassembly(void)
{
  tcp_frag *current, *next;
  int i;

  empty_tcp_stream = TRUE;
  incomplete_tcp_stream = FALSE;
  find_addr[TCP_STREAM] = FALSE;
  find_index[TCP_STREAM] = FALSE;
  for( i=0; i<2; i++ ) {
    seq[i] = 0;
    memset(src_addr[i], '\0', MAX_IPADDR_LEN);
    src_port[i] = 0;
    memset(ip_address[i], '\0', MAX_IPADDR_LEN);
    port[i] = 0;
    bytes_written[i] = 0;
    current = frags[i];
    while( current ) {
      next = current->next;
      g_free( current->data );
      g_free( current );
      current = next;
    }
    frags[i] = NULL;
  }
}

static void
write_packet_data( int idx, tcp_stream_chunk *sc, const char *data )
{
  size_t ret;

  ret = fwrite( sc, 1, sizeof(tcp_stream_chunk), data_out_file );
  DISSECTOR_ASSERT(sizeof(tcp_stream_chunk) == ret);

  ret = fwrite( data, 1, sc->dlen, data_out_file );
  DISSECTOR_ASSERT(sc->dlen == ret);

  bytes_written[idx] += sc->dlen;
  empty_tcp_stream = FALSE;
}

/*
 * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 *
 * Local Variables:
 * c-basic-offset: 2
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * ex: set shiftwidth=2 tabstop=8 expandtab:
 * :indentSize=2:tabSize=8:noTabs=true:
 */