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/* mpeg.c
*
* MPEG file format decoder for the Wiretap library.
* Written by Shaun Jackman <sjackman@gmail.com>
* Copyright 2007 Shaun Jackman
*
* Wiretap Library
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "mpeg.h"
#include "wsutil/mpeg-audio.h"
#include "wtap-int.h"
#include <wsutil/buffer.h>
#include "file_wrappers.h"
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#define PES_PREFIX 1
#define PES_VALID(n) (((n) >> 8 & 0xffffff) == PES_PREFIX)
typedef struct {
nstime_t now;
time_t t0;
} mpeg_t;
static int
mpeg_resync(FILE_T fh, int *err)
{
gint64 offset = file_tell(fh);
int count = 0;
int byte = file_getc(fh);
while (byte != EOF) {
if (byte == 0xff && count > 0) {
byte = file_getc(fh);
if (byte != EOF && (byte & 0xe0) == 0xe0)
break;
} else
byte = file_getc(fh);
count++;
}
if (file_seek(fh, offset, SEEK_SET, err) == -1)
return 0;
return count;
}
#define SCRHZ 27000000
static gboolean
mpeg_read_packet(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr, Buffer *buf,
gboolean is_random, int *err, gchar **err_info)
{
mpeg_t *mpeg = (mpeg_t *)wth->priv;
guint32 n;
unsigned int packet_size;
nstime_t ts = mpeg->now;
/*
* All packets have at least 4 bytes in them. Read the first
* 4 bytes and determine whether it's a PES packet or not
* based on that.
*
* XXX - can an MPEG file contain a mixture of PES and non-PES
* packets? If not, can we determine whether the packets will
* be PES packets or not based on the magic number (i.e., if the
* file begins with 0x00 0x00 0x01, it contains PES packets,
* otherwise it doesn't)?
*/
if (!wtap_read_bytes_or_eof(fh, &n, sizeof n, err, err_info))
return FALSE;
if (file_seek(fh, -(gint64)(sizeof n), SEEK_CUR, err) == -1)
return FALSE;
n = g_ntohl(n);
if (PES_VALID(n)) {
gint64 offset = file_tell(fh);
guint8 stream;
if (!file_skip(fh, 3, err))
return FALSE;
if (!wtap_read_bytes(fh, &stream, sizeof stream, err, err_info))
return FALSE;
if (stream == 0xba) {
guint32 pack1;
guint32 pack0;
guint64 pack;
guint8 stuffing;
if (!wtap_read_bytes(fh, &pack1, sizeof pack1, err, err_info))
return FALSE;
if (!wtap_read_bytes(fh, &pack0, sizeof pack0, err, err_info))
return FALSE;
pack = (guint64)g_ntohl(pack1) << 32 | g_ntohl(pack0);
switch (pack >> 62) {
case 1:
if (!file_skip(fh, 1, err))
return FALSE;
if (!wtap_read_bytes(fh, &stuffing,
sizeof stuffing, err, err_info))
return FALSE;
stuffing &= 0x07;
packet_size = 14 + stuffing;
if (!is_random) {
guint64 bytes = pack >> 16;
guint64 ts_val =
(bytes >> 43 & 0x0007) << 30 |
(bytes >> 27 & 0x7fff) << 15 |
(bytes >> 11 & 0x7fff) << 0;
guint ext = (guint)((bytes >> 1) & 0x1ff);
guint64 cr = 300 * ts_val + ext;
guint rem = (guint)(cr % SCRHZ);
mpeg->now.secs
= mpeg->t0 + (time_t)(cr / SCRHZ);
mpeg->now.nsecs
= (int)(G_GINT64_CONSTANT(1000000000) * rem / SCRHZ);
}
ts = mpeg->now;
break;
default:
packet_size = 12;
}
} else {
guint16 length;
if (!wtap_read_bytes(fh, &length, sizeof length, err, err_info))
return FALSE;
length = g_ntohs(length);
packet_size = 6 + length;
}
if (file_seek(fh, offset, SEEK_SET, err) == -1)
return FALSE;
} else {
struct mpa mpa;
MPA_UNMARSHAL(&mpa, n);
if (MPA_VALID(&mpa)) {
packet_size = MPA_BYTES(&mpa);
if (!is_random) {
mpeg->now.nsecs += MPA_DURATION_NS(&mpa);
if (mpeg->now.nsecs >= 1000000000) {
mpeg->now.secs++;
mpeg->now.nsecs -= 1000000000;
}
}
} else {
packet_size = mpeg_resync(fh, err);
if (packet_size == 0)
return FALSE;
}
}
if (!wtap_read_packet_bytes(fh, buf, packet_size, err, err_info))
return FALSE;
phdr->rec_type = REC_TYPE_PACKET;
/* XXX - relative, not absolute, time stamps */
if (!is_random) {
phdr->presence_flags = WTAP_HAS_TS;
phdr->ts = ts;
}
phdr->caplen = packet_size;
phdr->len = packet_size;
return TRUE;
}
static gboolean
mpeg_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
{
*data_offset = file_tell(wth->fh);
return mpeg_read_packet(wth, wth->fh, &wth->phdr, wth->frame_buffer,
FALSE, err, err_info);
}
static gboolean
mpeg_seek_read(wtap *wth, gint64 seek_off,
struct wtap_pkthdr *phdr, Buffer *buf,
int *err, gchar **err_info)
{
if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
return FALSE;
if (!mpeg_read_packet(wth, wth->random_fh, phdr, buf, TRUE, err,
err_info)) {
if (*err == 0)
*err = WTAP_ERR_SHORT_READ;
return FALSE;
}
return TRUE;
}
struct _mpeg_magic {
size_t len;
const gchar* match;
} magic[] = {
{ 3, "TAG" }, /* ID3v1 */
{ 3, "ID3" }, /* ID3v2 */
{ 3, "\0\0\1" }, /* MPEG PES */
{ 2, "\xff\xfb" }, /* MP3, taken from http://en.wikipedia.org/wiki/MP3#File_structure */
{ 0, NULL }
};
wtap_open_return_val
mpeg_open(wtap *wth, int *err, gchar **err_info)
{
char magic_buf[16];
struct _mpeg_magic* m;
mpeg_t *mpeg;
if (!wtap_read_bytes(wth->fh, magic_buf, sizeof magic_buf,
err, err_info)) {
if (*err != WTAP_ERR_SHORT_READ)
return WTAP_OPEN_ERROR;
return WTAP_OPEN_NOT_MINE;
}
for (m=magic; m->match; m++) {
if (memcmp(magic_buf, m->match, m->len) == 0)
goto good_magic;
}
return WTAP_OPEN_NOT_MINE;
good_magic:
/* This appears to be a file with MPEG data. */
if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
return WTAP_OPEN_ERROR;
wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MPEG;
wth->file_encap = WTAP_ENCAP_MPEG;
wth->file_tsprec = WTAP_TSPREC_NSEC;
wth->subtype_read = mpeg_read;
wth->subtype_seek_read = mpeg_seek_read;
wth->snapshot_length = 0;
mpeg = (mpeg_t *)g_malloc(sizeof(mpeg_t));
wth->priv = (void *)mpeg;
mpeg->now.secs = 0;
mpeg->now.nsecs = 0;
mpeg->t0 = mpeg->now.secs;
return WTAP_OPEN_MINE;
}
/*
* Editor modelines - http://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:
*/