aboutsummaryrefslogtreecommitdiffstats
path: root/packet-chdlc.c
blob: 19ee04fbeba6e966e77b5d7eb039e3bf28a15ace (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
/* packet-chdlc.c
 * Routines for Cisco HDLC packet disassembly
 *
 * $Id: packet-chdlc.c,v 1.21 2003/10/25 07:17:26 guy Exp $
 *
 * 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.
 */

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

#include <glib.h>
#include <epan/packet.h>
#include "etypes.h"
#include "prefs.h"
#include "chdlctypes.h"
#include <epan/resolv.h>
#include "packet-chdlc.h"
#include "packet-ppp.h"
#include "packet-ip.h"

/*
 * See section 4.3.1 of RFC 1547, and
 *
 *	http://www.nethelp.no/net/cisco-hdlc.txt
 */

static int proto_chdlc = -1;
static int hf_chdlc_addr = -1;
static int hf_chdlc_proto = -1;

static gint ett_chdlc = -1;

static int proto_slarp = -1;
static int hf_slarp_ptype = -1;
static int hf_slarp_address = -1;
static int hf_slarp_mysequence = -1;
static int hf_slarp_yoursequence = -1;

static gint ett_slarp = -1;

static dissector_handle_t data_handle;

/*
 * Protocol types for the Cisco HDLC format.
 *
 * As per the above, according to RFC 1547, these are "standard 16 bit
 * Ethernet protocol type code[s]", but 0x8035 is Reverse ARP, and
 * that is (at least according to the Linux ISDN code) not the
 * same as Cisco SLARP.
 *
 * In addition, 0x2000 is apparently the Cisco Discovery Protocol, but
 * on Ethernet those are encapsulated inside SNAP with an OUI of
 * OUI_CISCO, not OUI_ENCAP_ETHER.
 *
 * Perhaps we should set up a protocol table for those protocols
 * that differ between Ethernet and Cisco HDLC, and have the PPP
 * code first try that table and, if it finds nothing in that
 * table, call "ethertype()".  (Unfortunately, that means that -
 * assuming we had a Cisco SLARP dissector - said dissector were
 * disabled, SLARP packets would be dissected as Reverse ARP
 * packets, not as data.)
 */
#define CISCO_SLARP	0x8035	/* Cisco SLARP protocol */

static dissector_table_t subdissector_table;

static const value_string chdlc_address_vals[] = {
	{CHDLC_ADDR_UNICAST,   "Unicast"},
	{CHDLC_ADDR_MULTICAST, "Multicast"},
	{0,                    NULL}
};

const value_string chdlc_vals[] = {
	{0x2000,               "Cisco Discovery Protocol"},
	{ETHERTYPE_IP,         "IP"},
	{CISCO_SLARP,          "SLARP"},
	{ETHERTYPE_DEC_LB,     "DEC LanBridge"},
	{CHDLCTYPE_BPDU,       "Spanning Tree BPDU"},
	{ETHERTYPE_ATALK,      "Appletalk"},
	{ETHERTYPE_AARP,       "AARP"},
	{ETHERTYPE_IPX,        "Netware IPX/SPX"},
	{ETHERTYPE_ETHBRIDGE,  "Transparent Ethernet bridging" },
	{CHDLCTYPE_OSI,        "OSI" },
	{ETHERTYPE_MPLS,       "MPLS unicast"},
	{ETHERTYPE_MPLS_MULTI, "MPLS multicast"},
	{0,                     NULL}
};

void
capture_chdlc( const guchar *pd, int offset, int len, packet_counts *ld ) {
  if (!BYTES_ARE_IN_FRAME(offset, len, 4)) {
    ld->other++;
    return;
  }
  switch (pntohs(&pd[offset + 2])) {
    case ETHERTYPE_IP:
      capture_ip(pd, offset + 4, len, ld);
      break;
    default:
      ld->other++;
      break;
  }
}

void
chdlctype(guint16 chdlctype, tvbuff_t *tvb, int offset_after_chdlctype,
	  packet_info *pinfo, proto_tree *tree, proto_tree *fh_tree,
	  int chdlctype_id)
{
  tvbuff_t   *next_tvb;

  if (tree) {
    proto_tree_add_uint(fh_tree, chdlctype_id, tvb,
			offset_after_chdlctype - 2, 2, chdlctype);
  }

  next_tvb = tvb_new_subset(tvb, offset_after_chdlctype, -1, -1);

  /* do lookup with the subdissector table */
  if (!dissector_try_port(subdissector_table, chdlctype, next_tvb, pinfo, tree)) {
    if (check_col(pinfo->cinfo, COL_PROTOCOL))
      col_add_fstr(pinfo->cinfo, COL_PROTOCOL, "0x%04x", chdlctype);
    call_dissector(data_handle,next_tvb, pinfo, tree);
  }
}

static gint chdlc_fcs_decode = 0; /* 0 = No FCS, 1 = 16 bit FCS, 2 = 32 bit FCS */

static void
dissect_chdlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
  proto_item *ti;
  proto_tree *fh_tree = NULL;
  guint8     addr;
  guint16    proto;

  if (check_col(pinfo->cinfo, COL_PROTOCOL))
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "CHDLC");
  if (check_col(pinfo->cinfo, COL_INFO))
    col_clear(pinfo->cinfo, COL_INFO);

  switch (pinfo->p2p_dir) {

  case P2P_DIR_SENT:
    if (check_col(pinfo->cinfo, COL_RES_DL_SRC))
      col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
    if (check_col(pinfo->cinfo, COL_RES_DL_DST))
      col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
    break;

  case P2P_DIR_RECV:
    if (check_col(pinfo->cinfo, COL_RES_DL_SRC))
      col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
    if (check_col(pinfo->cinfo, COL_RES_DL_DST))
      col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
    break;

  default:
    if (check_col(pinfo->cinfo, COL_RES_DL_SRC))
      col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "N/A");
    if (check_col(pinfo->cinfo, COL_RES_DL_DST))
      col_set_str(pinfo->cinfo, COL_RES_DL_DST, "N/A");
    break;
  }

  addr = tvb_get_guint8(tvb, 0);
  proto = tvb_get_ntohs(tvb, 2);

  if (tree) {
    ti = proto_tree_add_item(tree, proto_chdlc, tvb, 0, 4, FALSE);
    fh_tree = proto_item_add_subtree(ti, ett_chdlc);

    proto_tree_add_uint(fh_tree, hf_chdlc_addr, tvb, 0, 1, addr);
  }

  decode_fcs(tvb, fh_tree, chdlc_fcs_decode, 2);

  chdlctype(proto, tvb, 4, pinfo, tree, fh_tree, hf_chdlc_proto);
}

void
proto_register_chdlc(void)
{
  static hf_register_info hf[] = {
    { &hf_chdlc_addr,
      { "Address", "chdlc.address", FT_UINT8, BASE_HEX,
        VALS(chdlc_address_vals), 0x0, "", HFILL }},
    { &hf_chdlc_proto,
      { "Protocol", "chdlc.protocol", FT_UINT16, BASE_HEX,
        VALS(chdlc_vals), 0x0, "", HFILL }},
  };
  static gint *ett[] = {
    &ett_chdlc,
  };

  module_t *chdlc_module;

  proto_chdlc = proto_register_protocol("Cisco HDLC", "CHDLC", "chdlc");
  proto_register_field_array(proto_chdlc, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));

/* subdissector code */
  subdissector_table = register_dissector_table("chdlctype",
	"Cisco HDLC frame type", FT_UINT16, BASE_HEX);

  register_dissector("chdlc", dissect_chdlc, proto_chdlc);

  /* Register the preferences for the chdlc protocol */
  chdlc_module = prefs_register_protocol(proto_chdlc, NULL);

  prefs_register_enum_preference(chdlc_module,
	"fcs_type",
	"CHDLC Frame Checksum Type",
	"The type of CHDLC frame checksum (none, 16-bit, 32-bit)",
	&chdlc_fcs_decode,
	fcs_options, FALSE);

}

void
proto_reg_handoff_chdlc(void)
{
  dissector_handle_t chdlc_handle;

  data_handle = find_dissector("data");
  chdlc_handle = find_dissector("chdlc");
  dissector_add("wtap_encap", WTAP_ENCAP_CHDLC, chdlc_handle);
  dissector_add("wtap_encap", WTAP_ENCAP_CHDLC_WITH_PHDR, chdlc_handle);
}

#define SLARP_REQUEST	0
#define SLARP_REPLY	1
#define SLARP_LINECHECK	2

static const value_string slarp_ptype_vals[] = {
	{SLARP_REQUEST,   "Request"},
	{SLARP_REPLY,     "Reply"},
	{SLARP_LINECHECK, "Line keepalive"},
	{0,               NULL}
};

static void
dissect_slarp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
  proto_item *ti;
  proto_tree *slarp_tree = NULL;
  guint32 code;
  guint32 address;
  guint32 mysequence;
  guint32 yoursequence;

  if (check_col(pinfo->cinfo, COL_PROTOCOL))
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "SLARP");
  if (check_col(pinfo->cinfo, COL_INFO))
    col_clear(pinfo->cinfo, COL_INFO);

  code = tvb_get_ntohl(tvb, 0);

  if (tree) {
    ti = proto_tree_add_item(tree, proto_slarp, tvb, 0, 14, FALSE);
    slarp_tree = proto_item_add_subtree(ti, ett_slarp);
  }

  switch (code) {

  case SLARP_REQUEST:
  case SLARP_REPLY:
    if (check_col(pinfo->cinfo, COL_INFO)) {
      tvb_memcpy(tvb, (guint8 *)&address, 4, 4);
      col_add_fstr(pinfo->cinfo, COL_INFO, "%s, from %s, mask %s",
        match_strval(code, slarp_ptype_vals),
        get_hostname(address),
        ip_to_str(tvb_get_ptr(tvb, 8, 4)));
    }
    if (tree) {
      proto_tree_add_uint(slarp_tree, hf_slarp_ptype, tvb, 0, 4, code);
      proto_tree_add_item(slarp_tree, hf_slarp_address, tvb, 4, 4, FALSE);
      proto_tree_add_text(slarp_tree, tvb, 8, 4,
			  "Netmask: %s", ip_to_str(tvb_get_ptr(tvb, 8, 4)));
    }
    break;

  case SLARP_LINECHECK:
    mysequence = tvb_get_ntohl(tvb, 4);
    yoursequence = tvb_get_ntohl(tvb, 8);
    if (check_col(pinfo->cinfo, COL_INFO)) {
      col_add_fstr(pinfo->cinfo, COL_INFO,
        "%s, outgoing sequence %u, returned sequence %u",
	match_strval(code, slarp_ptype_vals),
        mysequence, yoursequence);
    }
    if (tree) {
      proto_tree_add_uint(slarp_tree, hf_slarp_ptype, tvb, 0, 4, code);
      proto_tree_add_uint(slarp_tree, hf_slarp_mysequence, tvb, 4, 4,
			  mysequence);
      proto_tree_add_uint(slarp_tree, hf_slarp_mysequence, tvb, 8, 4,
			  yoursequence);
    }
    break;

  default:
    if (check_col(pinfo->cinfo, COL_INFO))
      col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown packet type 0x%08X", code);
    if (tree) {
      proto_tree_add_uint(slarp_tree, hf_slarp_ptype, tvb, 0, 4, code);
      call_dissector(data_handle, tvb_new_subset(tvb, 4, -1, -1), pinfo,
		     slarp_tree);
    }
    break;
  }
}

void
proto_register_slarp(void)
{
  static hf_register_info hf[] = {
    { &hf_slarp_ptype,
      { "Packet type", "slarp.ptype", FT_UINT32, BASE_DEC,
        VALS(slarp_ptype_vals), 0x0, "", HFILL }},
    { &hf_slarp_address,
      { "Address", "slarp.address", FT_IPv4, BASE_NONE,
        NULL, 0x0, "", HFILL }},
    /* XXX - need an FT_ for netmasks, which is like FT_IPV4 but doesn't
       get translated to a host name. */
    { &hf_slarp_mysequence,
      { "Outgoing sequence number", "slarp.mysequence", FT_UINT32, BASE_DEC,
        NULL, 0x0, "", HFILL }},
    { &hf_slarp_yoursequence,
      { "Returned sequence number", "slarp.yoursequence", FT_UINT32, BASE_DEC,
        NULL, 0x0, "", HFILL }},
  };
  static gint *ett[] = {
    &ett_chdlc,
    &ett_slarp,
  };

  proto_slarp = proto_register_protocol("Cisco SLARP", "SLARP", "slarp");
  proto_register_field_array(proto_slarp, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));
}

void
proto_reg_handoff_slarp(void)
{
  dissector_handle_t slarp_handle;

  slarp_handle = create_dissector_handle(dissect_slarp, proto_slarp);
  dissector_add("chdlctype", CISCO_SLARP, slarp_handle);
}