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
|
/* packet-udpcp.c
*
* Routines for UDPCP packet dissection (UDP-based reliable communication protocol).
* Described in the Open Base Station Initiative Reference Point 1 Specification
* (see https://web.archive.org/web/20171206005927/http://www.obsai.com/specs/RP1%20Spec%20v2_1.pdf, Appendix A)
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/* TODO:
* - Check for expected Acks and link between Data and Ack frames
* - Calculate/verify Checksum field
* - Sequence number analysis, i.e.
* - check next expected Msg Id
* - flag out-of-order Fragment Number within a MsgId?
*/
#include "config.h"
#include <epan/conversation.h>
#include <epan/reassemble.h>
#include <epan/expert.h>
#include <epan/prefs.h>
void proto_register_udpcp(void);
static int proto_udpcp = -1;
static int hf_udpcp_checksum = -1;
static int hf_udpcp_msg_type = -1;
static int hf_udpcp_version = -1;
static int hf_udpcp_packet_transfer_options = -1;
static int hf_udpcp_n = -1;
static int hf_udpcp_c = -1;
static int hf_udpcp_s = -1;
static int hf_udpcp_d = -1;
static int hf_udpcp_reserved = -1;
static int hf_udpcp_fragment_amount = -1;
static int hf_udpcp_fragment_number = -1;
static int hf_udpcp_message_id = -1;
static int hf_udpcp_message_data_length = -1;
static int hf_udpcp_payload = -1;
/* For reassembly */
static int hf_udpcp_fragments = -1;
static int hf_udpcp_fragment = -1;
static int hf_udpcp_fragment_overlap = -1;
static int hf_udpcp_fragment_overlap_conflict = -1;
static int hf_udpcp_fragment_multiple_tails = -1;
static int hf_udpcp_fragment_too_long_fragment = -1;
static int hf_udpcp_fragment_error = -1;
static int hf_udpcp_fragment_count = -1;
static int hf_udpcp_reassembled_in = -1;
static int hf_udpcp_reassembled_length = -1;
static int hf_udpcp_reassembled_data = -1;
/* Subtrees */
static gint ett_udpcp = -1;
static gint ett_udpcp_packet_transfer_options = -1;
static gint ett_udpcp_fragments = -1;
static gint ett_udpcp_fragment = -1;
static const fragment_items udpcp_frag_items = {
&ett_udpcp_fragment,
&ett_udpcp_fragments,
&hf_udpcp_fragments,
&hf_udpcp_fragment,
&hf_udpcp_fragment_overlap,
&hf_udpcp_fragment_overlap_conflict,
&hf_udpcp_fragment_multiple_tails,
&hf_udpcp_fragment_too_long_fragment,
&hf_udpcp_fragment_error,
&hf_udpcp_fragment_count,
&hf_udpcp_reassembled_in,
&hf_udpcp_reassembled_length,
&hf_udpcp_reassembled_data,
"UDPCP fragments"
};
static expert_field ei_udpcp_checksum_should_be_zero = EI_INIT;
static expert_field ei_udpcp_d_not_zero_for_data = EI_INIT;
static expert_field ei_udpcp_reserved_not_zero = EI_INIT;
static expert_field ei_udpcp_n_s_ack = EI_INIT;
static expert_field ei_udpcp_payload_wrong_size = EI_INIT;
static dissector_handle_t udpcp_handle;
void proto_reg_handoff_udpcp (void);
/* User definable values */
static range_t *global_udpcp_port_range = NULL;
#define DATA_FORMAT 0x01
#define ACK_FORMAT 0x02
static const value_string msg_type_vals[] = {
{ DATA_FORMAT, "Data Packet" },
{ ACK_FORMAT, "Ack Packet" },
{ 0, NULL }
};
/* Reassembly table. */
static reassembly_table udpcp_reassembly_table;
static gpointer udpcp_temporary_key(const packet_info *pinfo _U_, const guint32 id _U_, const void *data)
{
return (gpointer)data;
}
static gpointer udpcp_persistent_key(const packet_info *pinfo _U_, const guint32 id _U_,
const void *data)
{
return (gpointer)data;
}
static void udpcp_free_temporary_key(gpointer ptr _U_)
{
}
static void udpcp_free_persistent_key(gpointer ptr _U_)
{
}
static reassembly_table_functions udpcp_reassembly_table_functions =
{
g_direct_hash,
g_direct_equal,
udpcp_temporary_key,
udpcp_persistent_key,
udpcp_free_temporary_key,
udpcp_free_persistent_key
};
/**************************************************************************/
/* Preferences state */
/**************************************************************************/
/* Reassemble by default */
static gboolean global_udpcp_reassemble = TRUE;
/* By default do try to decode payload as XML/SOAP */
static gboolean global_udpcp_decode_payload_as_soap = TRUE;
static dissector_handle_t xml_handle;
/******************************/
/* Main dissection function. */
static int
dissect_udpcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
proto_tree *udpcp_tree;
proto_item *root_ti;
gint offset = 0;
/* Must be at least 12 bytes */
if (tvb_reported_length(tvb) < 12) {
return 0;
}
/* Must be Data or Ack format. */
guint32 msg_type = tvb_get_guint8(tvb, 4) >> 6;
if (msg_type != DATA_FORMAT && msg_type != ACK_FORMAT) {
return 0;
}
/* Protocol column */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "UDPCP");
/* Protocol root */
root_ti = proto_tree_add_item(tree, proto_udpcp, tvb, offset, -1, ENC_NA);
udpcp_tree = proto_item_add_subtree(root_ti, ett_udpcp);
/* Checksum */
guint32 checksum;
proto_item *checksum_ti = proto_tree_add_item_ret_uint(udpcp_tree, hf_udpcp_checksum, tvb, offset, 4, ENC_BIG_ENDIAN, &checksum);
offset += 4;
/* Msg-type */
proto_tree_add_item_ret_uint(udpcp_tree, hf_udpcp_msg_type, tvb, offset, 1, ENC_BIG_ENDIAN, &msg_type);
col_add_str(pinfo->cinfo, COL_INFO,
(msg_type == DATA_FORMAT) ? "[Data] " : "[Ack] ");
proto_item_append_text(root_ti, (msg_type == DATA_FORMAT) ? " [Data]" : " [Ack]");
/* Version */
proto_tree_add_item(udpcp_tree, hf_udpcp_version, tvb, offset, 1, ENC_BIG_ENDIAN);
/***************************/
/* Packet Transfer Options */
proto_item *packet_transfer_options_ti =
proto_tree_add_string_format(udpcp_tree, hf_udpcp_packet_transfer_options, tvb, offset, 2,
"", "Packet Transfer Options (");
proto_tree *packet_transfer_options_tree =
proto_item_add_subtree(packet_transfer_options_ti, ett_udpcp_packet_transfer_options);
guint32 n, c, s, d;
/* N */
proto_tree_add_item_ret_uint(packet_transfer_options_tree, hf_udpcp_n, tvb, offset, 1, ENC_BIG_ENDIAN, &n);
if (n) {
proto_item_append_text(packet_transfer_options_ti, "N");
}
/* C */
proto_tree_add_item_ret_uint(packet_transfer_options_tree, hf_udpcp_c, tvb, offset, 1, ENC_BIG_ENDIAN, &c);
if (c) {
proto_item_append_text(packet_transfer_options_ti, "C");
}
if (!c && checksum) {
/* Expert info warning that checksum should be 0 if !c */
expert_add_info(pinfo, checksum_ti, &ei_udpcp_checksum_should_be_zero);
}
/* S */
proto_tree_add_item_ret_uint(packet_transfer_options_tree, hf_udpcp_s, tvb, offset, 1, ENC_BIG_ENDIAN, &s);
offset++;
if (s) {
proto_item_append_text(packet_transfer_options_ti, "S");
}
/* D */
proto_item *d_ti = proto_tree_add_item_ret_uint(packet_transfer_options_tree, hf_udpcp_d, tvb, offset, 1, ENC_BIG_ENDIAN, &d);
if (d) {
proto_item_append_text(packet_transfer_options_ti, "D");
}
/* Expert info if D not zero for data */
if ((msg_type == DATA_FORMAT) && d) {
expert_add_info(pinfo, d_ti, &ei_udpcp_d_not_zero_for_data);
}
/* Reserved */
guint32 reserved;
proto_item *reserved_ti = proto_tree_add_item_ret_uint(packet_transfer_options_tree, hf_udpcp_reserved, tvb, offset, 1, ENC_BIG_ENDIAN, &reserved);
offset++;
/* Expert info if reserved not 0 */
if (reserved) {
expert_add_info(pinfo, reserved_ti, &ei_udpcp_reserved_not_zero);
}
proto_item_append_text(packet_transfer_options_ti, ")");
/*************************/
/* Fragment Amount & Fragment Number */
guint32 fragment_amount, fragment_number;
proto_tree_add_item_ret_uint(udpcp_tree, hf_udpcp_fragment_amount, tvb, offset, 1, ENC_BIG_ENDIAN, &fragment_amount);
offset++;
proto_tree_add_item_ret_uint(udpcp_tree, hf_udpcp_fragment_number, tvb, offset, 1, ENC_BIG_ENDIAN, &fragment_number);
offset++;
/* Message ID & Message Data Length */
guint32 message_id;
proto_tree_add_item_ret_uint(udpcp_tree, hf_udpcp_message_id, tvb, offset, 2, ENC_BIG_ENDIAN, &message_id);
col_append_fstr(pinfo->cinfo, COL_INFO, " Msg_ID=%3u", message_id);
offset += 2;
guint32 data_length;
proto_tree_add_item_ret_uint(udpcp_tree, hf_udpcp_message_data_length, tvb, offset, 2, ENC_BIG_ENDIAN, &data_length);
offset += 2;
if (msg_type == DATA_FORMAT) {
if (!data_length) {
/* This could just be a sync frame */
if (!message_id && !n && !s) {
col_append_str(pinfo->cinfo, COL_INFO, " [Sync]");
}
/* Nothing more to show here */
return offset;
}
/* Show if/when this frame should be acknowledged */
if (!n && !s) {
proto_item_append_text(packet_transfer_options_ti, " (All packets ACKd)");
}
else if (!n && s) {
proto_item_append_text(packet_transfer_options_ti, " (Last fragment ACKd)");
}
if (n) {
proto_item_append_text(packet_transfer_options_ti, " (Not ACKd)");
}
/* Show fragment numbering. Ignore confusing 0-based fragment numbering.. */
col_append_fstr(pinfo->cinfo, COL_INFO, " [Frag %u/%u]",
fragment_number+1, fragment_amount);
/* There is data */
if ((fragment_amount == 1) && (fragment_number == 0)) {
/* Not fragmented - show payload now */
proto_item *data_ti = proto_tree_add_item(udpcp_tree, hf_udpcp_payload, tvb, offset, -1, ENC_ASCII);
col_append_fstr(pinfo->cinfo, COL_INFO, " Data (%u bytes)", data_length);
/* Check length is as signalled */
if (data_length != (guint32)tvb_reported_length_remaining(tvb, offset)) {
expert_add_info_format(pinfo, data_ti, &ei_udpcp_payload_wrong_size, "Data length field was %u but %u bytes found",
data_length, tvb_reported_length_remaining(tvb, offset));
}
if (global_udpcp_decode_payload_as_soap) {
/* Send to XML dissector */
tvbuff_t *next_tvb = tvb_new_subset_remaining(tvb, offset);
call_dissector_only(xml_handle, next_tvb, pinfo, tree, NULL);
}
}
else {
/* Fragmented */
if (global_udpcp_reassemble) {
/* Reassembly */
/* Set fragmented flag. */
gboolean save_fragmented = pinfo->fragmented;
pinfo->fragmented = TRUE;
fragment_head *fh;
guint frag_data_len = tvb_reported_length_remaining(tvb, offset);
/* Add this fragment into reassembly */
fh = fragment_add_seq_check(&udpcp_reassembly_table, tvb, offset, pinfo,
message_id, /* id */
GUINT_TO_POINTER(message_id), /* data */
fragment_number, /* frag_number */
frag_data_len, /* frag_data_len */
(fragment_number < (fragment_amount-1)) /* more_frags */
);
gboolean update_col_info = TRUE;
/* See if this completes an SDU */
tvbuff_t *next_tvb = process_reassembled_data(tvb, offset, pinfo, "Reassembled UDPCP Payload",
fh, &udpcp_frag_items,
&update_col_info, udpcp_tree);
if (next_tvb) {
/* Have reassembled data */
proto_item *data_ti = proto_tree_add_item(udpcp_tree, hf_udpcp_payload, next_tvb, 0, -1, ENC_ASCII);
col_append_fstr(pinfo->cinfo, COL_INFO, " Reassembled Data (%u bytes)", data_length);
/* Check length is as signalled */
if (data_length != (guint32)tvb_reported_length_remaining(next_tvb, 0)) {
expert_add_info_format(pinfo, data_ti, &ei_udpcp_payload_wrong_size, "Data length field was %u but %u bytes found (reassembled)",
data_length, tvb_reported_length_remaining(next_tvb, 0));
}
if (global_udpcp_decode_payload_as_soap) {
/* Send to XML dissector */
call_dissector_only(xml_handle, next_tvb, pinfo, tree, NULL);
}
}
/* Restore fragmented flag */
pinfo->fragmented = save_fragmented;
}
}
}
else if (msg_type == ACK_FORMAT) {
/* N and S should be set - complain if not */
if (!n || !s) {
expert_add_info(pinfo, packet_transfer_options_ti, &ei_udpcp_n_s_ack);
}
if (d) {
/* Duplicate data detected */
proto_item_append_text(packet_transfer_options_ti, " (duplicate)");
col_append_str(pinfo->cinfo, COL_INFO, " (duplicate)");
}
}
return offset;
}
void
proto_register_udpcp(void)
{
static hf_register_info hf[] = {
{ &hf_udpcp_checksum,
{ "Checksum", "udpcp.checksum", FT_UINT32, BASE_HEX,
NULL, 0x0, "Adler32 checksum", HFILL }},
{ &hf_udpcp_msg_type,
{ "Msg Type", "udpcp.msg-type", FT_UINT8, BASE_HEX,
VALS(msg_type_vals), 0xc0, NULL, HFILL }},
{ &hf_udpcp_version,
{ "Version", "udpcp.version", FT_UINT8, BASE_HEX,
NULL, 0x38, NULL, HFILL }},
{ &hf_udpcp_packet_transfer_options,
{ "Packet Transport Options", "udpcp.pto", FT_STRING, BASE_NONE,
NULL, 0x0, NULL, HFILL }},
{ &hf_udpcp_n,
{ "N", "udpcp.n", FT_UINT8, BASE_HEX,
NULL, 0x04, "Along with S bit, indicates whether acknowledgements should be sent", HFILL }},
{ &hf_udpcp_c,
{ "C", "udpcp.c", FT_UINT8, BASE_HEX,
NULL, 0x02, "When set, the checksum should be valid", HFILL }},
{ &hf_udpcp_s,
{ "S", "udpcp.s", FT_UINT8, BASE_HEX,
NULL, 0x01, "Along with N bit, indicates whether acknowledgements should be sent", HFILL }},
{ &hf_udpcp_d,
{ "D", "udpcp.d", FT_UINT8, BASE_HEX,
NULL, 0x80, "For ACK, indicates duplicate ACK", HFILL }},
{ &hf_udpcp_reserved,
{ "Reserved", "udpcp.reserved", FT_UINT8, BASE_HEX,
NULL, 0x7f, "Shall be set to 0", HFILL }},
{ &hf_udpcp_fragment_amount,
{ "Fragment Amount", "udpcp.fragment-amount", FT_UINT8, BASE_DEC,
NULL, 0x0, "Total number of fragments of a message", HFILL }},
{ &hf_udpcp_fragment_number,
{ "Fragment Number", "udpcp.fragment-number", FT_UINT8, BASE_DEC,
NULL, 0x0, "Fragment number of current packet within msg. Starts at 0", HFILL }},
{ &hf_udpcp_message_id,
{ "Message ID", "udpcp.message-id", FT_UINT16, BASE_DEC,
NULL, 0x0, NULL, HFILL }},
{ &hf_udpcp_message_data_length,
{ "Message Data Length", "udpcp.message-data-length", FT_UINT16, BASE_DEC,
NULL, 0x0, NULL, HFILL }},
{ &hf_udpcp_payload,
{ "Payload", "udpcp.payload", FT_BYTES, BASE_SHOW_ASCII_PRINTABLE,
NULL, 0x0, "Complete or reassembled payload", HFILL }},
/* Reassembly */
{ &hf_udpcp_fragment,
{ "Fragment", "udpcp.fragment", FT_FRAMENUM, BASE_NONE,
NULL, 0x0, NULL, HFILL }},
{ &hf_udpcp_fragments,
{ "Fragments", "udpcp.fragments", FT_BYTES, BASE_NONE,
NULL, 0x0, NULL, HFILL }},
{ &hf_udpcp_fragment_overlap,
{ "Fragment overlap", "udpcp.fragment.overlap", FT_BOOLEAN, BASE_NONE,
NULL, 0x0, "Fragment overlaps with other fragments", HFILL }},
{ &hf_udpcp_fragment_overlap_conflict,
{ "Conflicting data in fragment overlap", "udpcp.fragment.overlap.conflict",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Overlapping fragments contained conflicting data", HFILL }},
{ &hf_udpcp_fragment_multiple_tails,
{ "Multiple tail fragments found", "udpcp.fragment.multipletails",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Several tails were found when defragmenting the packet", HFILL }},
{ &hf_udpcp_fragment_too_long_fragment,
{ "Fragment too long", "udpcp.fragment.toolongfragment",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Fragment contained data past end of packet", HFILL }},
{ &hf_udpcp_fragment_error,
{ "Defragmentation error", "udpcp.fragment.error", FT_FRAMENUM, BASE_NONE,
NULL, 0x0, "Defragmentation error due to illegal fragments", HFILL }},
{ &hf_udpcp_fragment_count,
{ "Fragment count", "udpcp.fragment.count", FT_UINT32, BASE_DEC,
NULL, 0x0, NULL, HFILL }},
{ &hf_udpcp_reassembled_in,
{ "Reassembled payload in frame", "udpcp.reassembled_in", FT_FRAMENUM, BASE_NONE,
NULL, 0x0, "This payload packet is reassembled in this frame", HFILL }},
{ &hf_udpcp_reassembled_length,
{ "Reassembled payload length", "udpcp.reassembled.length", FT_UINT32, BASE_DEC,
NULL, 0x0, "The total length of the reassembled payload", HFILL }},
{ &hf_udpcp_reassembled_data,
{ "Reassembled data", "udpcp.reassembled.data", FT_BYTES, BASE_NONE,
NULL, 0x0, "The reassembled payload", HFILL }},
};
static gint *ett[] = {
&ett_udpcp,
&ett_udpcp_packet_transfer_options,
&ett_udpcp_fragments,
&ett_udpcp_fragment
};
static ei_register_info ei[] = {
{ &ei_udpcp_checksum_should_be_zero, { "udpcp.checksum-not-zero", PI_CHECKSUM, PI_WARN, "Checksum should be zero if !C.", EXPFILL }},
{ &ei_udpcp_d_not_zero_for_data, { "udpcp.d-not-zero-data", PI_SEQUENCE, PI_ERROR, "D should be zero for data frames", EXPFILL }},
{ &ei_udpcp_reserved_not_zero, { "udpcp.reserved-not-zero", PI_MALFORMED, PI_WARN, "Reserved bits not zero", EXPFILL }},
{ &ei_udpcp_n_s_ack, { "udpcp.n-s-set-ack", PI_MALFORMED, PI_ERROR, "N or S set for ACK frame", EXPFILL }},
{ &ei_udpcp_payload_wrong_size, { "udpcp.payload-wrong-size", PI_MALFORMED, PI_ERROR, "Payload seen does not match size field", EXPFILL }},
};
module_t *udpcp_module;
expert_module_t *expert_udpcp;
proto_udpcp = proto_register_protocol("UDPCP", "UDPCP", "udpcp");
proto_register_field_array(proto_udpcp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_udpcp = expert_register_protocol(proto_udpcp);
expert_register_field_array(expert_udpcp, ei, array_length(ei));
udpcp_handle = register_dissector("udpcp", dissect_udpcp, proto_udpcp);
/* Register reassembly table. */
reassembly_table_register(&udpcp_reassembly_table,
&udpcp_reassembly_table_functions);
/* Preferences */
udpcp_module = prefs_register_protocol(proto_udpcp, NULL);
/* Payload reassembly */
prefs_register_bool_preference(udpcp_module, "attempt_reassembly",
"Reassemble payload",
"",
&global_udpcp_reassemble);
/* Whether to try XML dissector on payload.
* TODO: are there any other payload types we might see? */
prefs_register_bool_preference(udpcp_module, "attempt_xml_decode",
"Call XML dissector for payload",
"",
&global_udpcp_decode_payload_as_soap);
}
static void
apply_udpcp_prefs(void)
{
global_udpcp_port_range = prefs_get_range_value("udpcp", "udp.port");
}
void
proto_reg_handoff_udpcp(void)
{
dissector_add_uint_range_with_preference("udp.port", "", udpcp_handle);
apply_udpcp_prefs();
xml_handle = find_dissector("xml");
}
/*
* Editor modelines - https://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:
*/
|