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
|
/* packet-h261.c
*
* Routines for ITU-T Recommendation H.261 dissection
*
* Copyright 2000, Philips Electronics N.V.
* Andreas Sikkema <h323@ramdyne.nl>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* This dissector tries to dissect the H.261 protocol according to Annex C
* of ITU-T Recommendation H.225.0 (02/98)
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/rtp_pt.h>
#include <epan/iax2_codec_type.h>
void proto_register_h261(void);
void proto_reg_handoff_h261(void);
static dissector_handle_t h261_handle;
/* H.261 header fields */
static int proto_h261;
static int hf_h261_sbit;
static int hf_h261_ebit;
static int hf_h261_ibit;
static int hf_h261_vbit;
static int hf_h261_gobn;
static int hf_h261_mbap;
static int hf_h261_quant;
static int hf_h261_hmvd; /* Mislabeled in a figure in section C.3.1 as HMDV */
static int hf_h261_vmvd;
static int hf_h261_data;
/* H.261 fields defining a sub tree */
static int ett_h261;
static int
dissect_h261( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_ )
{
proto_item *ti = NULL;
proto_tree *h261_tree = NULL;
unsigned int offset = 0;
static int * const bits[] = {
/* SBIT 1st octet, 3 bits */
&hf_h261_sbit,
/* EBIT 1st octet, 3 bits */
&hf_h261_ebit,
/* I flag, 1 bit */
&hf_h261_ibit,
/* V flag, 1 bit */
&hf_h261_vbit,
NULL
};
col_set_str(pinfo->cinfo, COL_PROTOCOL, "H.261");
col_set_str(pinfo->cinfo, COL_INFO, "H.261 message");
ti = proto_tree_add_item( tree, proto_h261, tvb, offset, -1, ENC_NA);
h261_tree = proto_item_add_subtree( ti, ett_h261 );
proto_tree_add_bitmask_list(h261_tree, tvb, offset, 1, bits, ENC_NA);
offset++;
/* GOBN 2nd octet, 4 bits */
proto_tree_add_item( h261_tree, hf_h261_gobn, tvb, offset, 1, ENC_NA);
/* MBAP 2nd octet, 4 bits, 3rd octet 1 bit */
proto_tree_add_item( h261_tree, hf_h261_mbap, tvb, offset, 2, ENC_BIG_ENDIAN);
offset++;
/* QUANT 3rd octet, 5 bits (starting at bit 2!) */
proto_tree_add_item( h261_tree, hf_h261_quant, tvb, offset, 1, ENC_NA);
/* HMVD 3rd octet 2 bits, 4th octet 3 bits */
proto_tree_add_item( h261_tree, hf_h261_hmvd, tvb, offset, 2, ENC_BIG_ENDIAN);
offset++;
/* VMVD 4th octet, last 5 bits */
proto_tree_add_item( h261_tree, hf_h261_vmvd, tvb, offset, 1, ENC_NA);
offset++;
/* The rest of the packet is the H.261 stream */
proto_tree_add_item( h261_tree, hf_h261_data, tvb, offset, -1, ENC_NA);
return tvb_captured_length(tvb);
}
void
proto_register_h261(void)
{
static hf_register_info hf[] =
{
{
&hf_h261_sbit,
{
"Start bit position",
"h261.sbit",
FT_UINT8,
BASE_DEC,
NULL,
0xe0,
NULL, HFILL
}
},
{
&hf_h261_ebit,
{
"End bit position",
"h261.ebit",
FT_UINT8,
BASE_DEC,
NULL,
0x1c,
NULL, HFILL
}
},
{
&hf_h261_ibit,
{
"Intra frame encoded data flag",
"h261.i",
FT_BOOLEAN,
8,
NULL,
0x02,
NULL, HFILL
}
},
{
&hf_h261_vbit,
{
"Motion vector flag",
"h261.v",
FT_BOOLEAN,
8,
NULL,
0x01,
NULL, HFILL
}
},
{
&hf_h261_gobn,
{
"GOB Number",
"h261.gobn",
FT_UINT8,
BASE_DEC,
NULL,
0xF0,
NULL, HFILL
}
},
{
&hf_h261_mbap,
{
"Macroblock address predictor",
"h261.mbap",
FT_UINT16,
BASE_DEC,
NULL,
0x0F80,
NULL, HFILL
}
},
{
&hf_h261_quant,
{
"Quantizer",
"h261.quant",
FT_UINT8,
BASE_DEC,
NULL,
0x7C,
NULL, HFILL
}
},
{
&hf_h261_hmvd,
{
"Horizontal motion vector data",
"h261.hmvd",
FT_UINT16,
BASE_DEC,
NULL,
0x03E0,
NULL, HFILL
}
},
{
&hf_h261_vmvd,
{
"Vertical motion vector data",
"h261.vmvd",
FT_UINT8,
BASE_DEC,
NULL,
0x0,
NULL, HFILL
}
},
{
&hf_h261_data,
{
"H.261 stream",
"h261.stream",
FT_BYTES,
BASE_NONE,
NULL,
0x0,
NULL, HFILL
}
},
};
static int *ett[] =
{
&ett_h261,
};
proto_h261 = proto_register_protocol("ITU-T Recommendation H.261",
"H.261", "h261");
proto_register_field_array(proto_h261, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
h261_handle = register_dissector("h261", dissect_h261, proto_h261);
}
void
proto_reg_handoff_h261(void)
{
dissector_add_uint("rtp.pt", PT_H261, h261_handle);
dissector_add_uint("iax2.codec", AST_FORMAT_H261, h261_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
|
