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/* 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 "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);
static int proto_mpeg_audio = -1;
static int hf_mpeg_audio_data = -1;
static int hf_mpeg_audio_padbytes = -1;
static int hf_id3v1 = -1;
static int hf_id3v2 = -1;
static gboolean
dissect_mpeg_audio_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
guint32 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 FALSE; /* not enough data for an MPEG audio frame */
h = tvb_get_ntohl(tvb, 0);
MPA_UNMARSHAL(&mpa, h);
if (!MPA_SYNC_VALID(&mpa))
return FALSE;
if (!MPA_VERSION_VALID(&mpa))
return FALSE;
if (!MPA_LAYER_VALID(&mpa))
return FALSE;
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);
}
if (tree == NULL)
return TRUE;
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, TRUE, pinfo);
offset = dissect_mpeg_audio_Audio(tvb, offset, &asn1_ctx,
tree, proto_mpeg_audio);
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);
}
}
return TRUE;
}
static void
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);
if (tree == NULL)
return;
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, TRUE, pinfo);
dissect_mpeg_audio_ID3v1(tvb, 0, &asn1_ctx,
tree, hf_id3v1);
}
static void
dissect_id3v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
col_set_str(pinfo->cinfo, COL_PROTOCOL, "ID3v2");
col_clear(pinfo->cinfo, COL_INFO);
proto_tree_add_item(tree, hf_id3v2, tvb,
0, -1, ENC_NA);
}
static gboolean
dissect_mpeg_audio(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
int magic;
if (!tvb_bytes_exist(tvb, 0, 3))
return FALSE; /* not enough data for an ID tag or audio frame */
magic = tvb_get_ntoh24(tvb, 0);
switch (magic) {
case 0x544147: /* TAG */
dissect_id3v1(tvb, pinfo, tree);
return TRUE;
case 0x494433: /* ID3 */
dissect_id3v2(tvb, pinfo, tree);
return TRUE;
default:
return dissect_mpeg_audio_frame(tvb, pinfo, tree);
}
}
void
proto_register_mpeg_audio(void)
{
static hf_register_info hf[] = {
#include "packet-mpeg-audio-hfarr.c"
{ &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 }},
{ &hf_id3v2,
{ "ID3v2", "mpeg-audio.id3v2",
FT_NONE, BASE_NONE, NULL, 0, NULL, HFILL }},
};
static gint *ett[] = {
#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));
}
void
proto_reg_handoff_mpeg_audio(void)
{
heur_dissector_add("mpeg", dissect_mpeg_audio, "MPEG Audio", "mpeg_audio", proto_mpeg_audio, HEURISTIC_ENABLE);
}
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