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
|
/* MPEG audio packet decoder.
* Written by Shaun Jackman <sjackman@gmail.com>.
* Copyright 2007 Shaun Jackman
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/asn1.h>
#include <wsutil/mpeg-audio.h>
#include <wsutil/array.h>
#include "packet-per.h"
#include "packet-mpeg-audio-hf.c"
#include "packet-mpeg-audio-ett.c"
#include "packet-mpeg-audio-fn.c"
void proto_register_mpeg_audio(void);
void proto_reg_handoff_mpeg_audio(void);
dissector_handle_t mpeg_audio_handle;
static int proto_mpeg_audio;
static dissector_handle_t id3v2_handle;
static int hf_mpeg_audio_header;
static int hf_mpeg_audio_data;
static int hf_mpeg_audio_padbytes;
static int hf_id3v1;
static int ett_mpeg_audio;
static bool
test_mpeg_audio(tvbuff_t *tvb, int offset)
{
uint32_t hdr;
struct mpa mpa;
if (!tvb_bytes_exist(tvb, offset, 4))
return false;
if (tvb_strneql(tvb, offset, "TAG", 3) == 0)
return true;
if (tvb_strneql(tvb, offset, "ID3", 3) == 0)
return true;
hdr = tvb_get_uint32(tvb, offset, ENC_BIG_ENDIAN);
MPA_UNMARSHAL(&mpa, hdr);
return MPA_VALID(&mpa);
}
static int
mpeg_resync(tvbuff_t *tvb, int offset)
{
uint32_t hdr;
struct mpa mpa;
/* This only looks to resync on another frame; it doesn't
* look for an ID3 tag.
*/
offset = tvb_find_uint8(tvb, offset, -1, '\xff');
while (offset != -1 && tvb_bytes_exist(tvb, offset, 4)) {
hdr = tvb_get_uint32(tvb, offset, ENC_BIG_ENDIAN);
MPA_UNMARSHAL(&mpa, hdr);
if (MPA_VALID(&mpa)) {
return offset;
}
offset = tvb_find_uint8(tvb, offset + 1, -1, '\xff');
}
return tvb_reported_length(tvb);
}
static int
dissect_mpeg_audio_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
uint32_t h;
struct mpa mpa;
int data_size = 0;
asn1_ctx_t asn1_ctx;
int offset = 0;
static const char *version_names[] = { "1", "2", "2.5" };
if (!tvb_bytes_exist(tvb, 0, 4))
return 0;
h = tvb_get_ntohl(tvb, 0);
MPA_UNMARSHAL(&mpa, h);
if (!MPA_SYNC_VALID(&mpa) || !MPA_VERSION_VALID(&mpa) || !MPA_LAYER_VALID(&mpa)) {
return 0;
}
col_add_fstr(pinfo->cinfo, COL_PROTOCOL,
"MPEG-%s", version_names[mpa_version(&mpa)]);
col_add_fstr(pinfo->cinfo, COL_INFO,
"Audio Layer %d", mpa_layer(&mpa) + 1);
if (MPA_BITRATE_VALID(&mpa) && MPA_FREQUENCY_VALID(&mpa)) {
data_size = (int)(MPA_DATA_BYTES(&mpa) - sizeof mpa);
col_append_fstr(pinfo->cinfo, COL_INFO,
", %d kb/s, %g kHz",
mpa_bitrate(&mpa) / 1000,
mpa_frequency(&mpa) / (float)1000);
}
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, true, pinfo);
offset = dissect_mpeg_audio_Audio(tvb, offset, &asn1_ctx,
tree, hf_mpeg_audio_header);
if (data_size > 0) {
unsigned int padding;
proto_tree_add_item(tree, hf_mpeg_audio_data, tvb,
offset / 8, data_size, ENC_NA);
offset += data_size * 8;
padding = mpa_padding(&mpa);
if (padding > 0) {
proto_tree_add_item(tree, hf_mpeg_audio_padbytes, tvb,
offset / 8, padding, ENC_NA);
offset += padding * 8;
}
}
return offset / 8;
}
static int
dissect_id3v1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
asn1_ctx_t asn1_ctx;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "ID3v1");
col_clear(pinfo->cinfo, COL_INFO);
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, true, pinfo);
return dissect_mpeg_audio_ID3v1(tvb, 0, &asn1_ctx,
tree, hf_id3v1);
}
static int
dissect_mpeg_audio(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_item *ti;
proto_tree *mpeg_audio_tree;
int magic, offset = 0;
uint32_t frame_len;
tvbuff_t *next_tvb;
ti = proto_tree_add_item(tree, proto_mpeg_audio, tvb, offset, -1, ENC_NA);
mpeg_audio_tree = proto_item_add_subtree(ti, ett_mpeg_audio);
while (tvb_reported_length_remaining(tvb, offset) >= 4) {
next_tvb = tvb_new_subset_remaining(tvb, offset);
magic = tvb_get_ntoh24(next_tvb, 0);
switch (magic) {
case 0x544147: /* TAG */
offset += dissect_id3v1(next_tvb, pinfo, mpeg_audio_tree);
break;
case 0x494433: /* ID3 */
offset += call_dissector(id3v2_handle, tvb, pinfo, mpeg_audio_tree);
break;
default:
frame_len = dissect_mpeg_audio_frame(next_tvb, pinfo, mpeg_audio_tree);
if (frame_len == 0) {
frame_len = mpeg_resync(next_tvb, 0);
}
offset += frame_len;
}
}
return tvb_reported_length(tvb);
}
static bool
dissect_mpeg_audio_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
if (!test_mpeg_audio(tvb, 0)) {
return false;
}
dissect_mpeg_audio(tvb, pinfo, tree, data);
return true;
}
void
proto_register_mpeg_audio(void)
{
static hf_register_info hf[] = {
#include "packet-mpeg-audio-hfarr.c"
{ &hf_mpeg_audio_header,
{ "Frame Header", "mpeg-audio.header",
FT_NONE, BASE_NONE, NULL, 0, NULL, HFILL }},
{ &hf_mpeg_audio_data,
{ "Data", "mpeg-audio.data",
FT_BYTES, BASE_NONE, NULL, 0, NULL, HFILL }},
{ &hf_mpeg_audio_padbytes,
{ "Padding", "mpeg-audio.padbytes",
FT_BYTES, BASE_NONE, NULL, 0, NULL, HFILL }},
{ &hf_id3v1,
{ "ID3v1", "mpeg-audio.id3v1",
FT_NONE, BASE_NONE, NULL, 0, NULL, HFILL }},
};
static int *ett[] = {
&ett_mpeg_audio,
#include "packet-mpeg-audio-ettarr.c"
};
proto_mpeg_audio = proto_register_protocol("Moving Picture Experts Group Audio", "MPEG Audio", "mpeg-audio");
proto_register_field_array(proto_mpeg_audio, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
mpeg_audio_handle = register_dissector("mpeg-audio", dissect_mpeg_audio, proto_mpeg_audio);
}
void
proto_reg_handoff_mpeg_audio(void)
{
dissector_add_string("media_type", "audio/mpeg", mpeg_audio_handle);
/* "audio/mp3" used by Chrome before 2020 */
/* https://chromium.googlesource.com/chromium/src/+/842f46a95f49e24534ad35c7a71e5c425d426550 */
dissector_add_string("media_type", "audio/mp3", mpeg_audio_handle);
heur_dissector_add("mpeg", dissect_mpeg_audio_heur, "MPEG Audio", "mpeg_audio", proto_mpeg_audio, HEURISTIC_ENABLE);
id3v2_handle = find_dissector("id3v2");
}
|
