* Written by Weston Schmidt <weston_schmidt@alumni.purdue.edu>
* Copyright 2012 Weston Schmidt
*
- * $Id$
- *
* Wiretap Library
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
-#ifdef HAVE_CONFIG_H
#include "config.h"
-#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#include "mp2t.h"
#include "wtap-int.h"
-#include "buffer.h"
+#include <wsutil/buffer.h>
#include "file_wrappers.h"
#include <errno.h>
#include <stdlib.h>
#define MP2T_SYNC_BYTE 0x47
#define MP2T_SIZE 188
-#define MP2T_QAM256_BITRATE 38810700 /* bits per second */
#define MP2T_QAM64_BITRATE 26970350 /* bits per second */
+#define MP2T_PCR_CLOCK 27000000 /* cycles per second - 27MHz */
/* we try to detect trailing data up to 40 bytes after each packet */
#define TRAILER_LEN_MAX 40
typedef struct {
- guint32 offset;
- struct wtap_nstime now;
+ guint32 start_offset;
+ guint64 bitrate;
/* length of trailing data (e.g. FEC) that's appended after each packet */
guint8 trailer_len;
} mp2t_filetype_t;
static gboolean
-mp2t_read_data(guint8 *dest, int length, int *err, gchar **err_info, FILE_T fh)
+mp2t_read_packet(mp2t_filetype_t *mp2t, FILE_T fh, gint64 offset,
+ struct wtap_pkthdr *phdr, Buffer *buf, int *err,
+ gchar **err_info)
{
- int bytes_read;
+ guint64 tmp;
- bytes_read = file_read(dest, length, fh);
- if (length != bytes_read) {
- *err = file_error(fh, err_info);
- /* bytes_read==0 is end of file, not a short read */
- if (bytes_read>0 && *err == 0) {
- *err = WTAP_ERR_SHORT_READ;
- }
+ /*
+ * MP2T_SIZE will always be less than WTAP_MAX_PACKET_SIZE, so
+ * we don't have to worry about the packet being too big.
+ */
+ ws_buffer_assure_space(buf, MP2T_SIZE);
+ if (!wtap_read_bytes_or_eof(fh, ws_buffer_start_ptr(buf), MP2T_SIZE, err, err_info))
return FALSE;
- }
+
+ phdr->rec_type = REC_TYPE_PACKET;
+
+ /* XXX - relative, not absolute, time stamps */
+ phdr->presence_flags = WTAP_HAS_TS;
+
+ /*
+ * Every packet in an MPEG2-TS stream is has a fixed size of
+ * MP2T_SIZE plus the number of trailer bytes.
+ *
+ * We assume that the bits in the transport stream are supplied at
+ * a constant rate; is that guaranteed by all media that use
+ * MPEG2-TS? If so, the time offset, from the beginning of the
+ * stream, of a given packet is the packet offset, in bits, divided
+ * by the bitrate.
+ *
+ * It would be really cool to be able to configure the bitrate, in
+ * case our attempt to guess it from the PCRs of one of the programs
+ * doesn't get the right answer.
+ */
+ tmp = ((guint64)(offset - mp2t->start_offset) * 8); /* offset, in bits */
+ phdr->ts.secs = (time_t)(tmp / mp2t->bitrate);
+ phdr->ts.nsecs = (int)((tmp % mp2t->bitrate) * 1000000000 / mp2t->bitrate);
+
+ phdr->caplen = MP2T_SIZE;
+ phdr->len = MP2T_SIZE;
return TRUE;
}
mp2t_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
{
mp2t_filetype_t *mp2t;
- guint64 tmp;
mp2t = (mp2t_filetype_t*) wth->priv;
- *data_offset = mp2t->offset;
- /* read only the actual mpeg2 ts packet, not including a trailer */
- buffer_assure_space(wth->frame_buffer, MP2T_SIZE);
- if (FALSE == mp2t_read_data(buffer_start_ptr(wth->frame_buffer),
- MP2T_SIZE, err, err_info, wth->fh))
- {
+ *data_offset = file_tell(wth->fh);
+
+ if (!mp2t_read_packet(mp2t, wth->fh, *data_offset, &wth->phdr,
+ wth->frame_buffer, err, err_info)) {
return FALSE;
}
/* if there's a trailer, skip it and go to the start of the next packet */
- if (mp2t->trailer_len!=0 &&
- (-1 == file_seek(wth->fh, mp2t->trailer_len, SEEK_CUR, err))) {
- return FALSE;
+ if (mp2t->trailer_len!=0) {
+ if (-1 == file_seek(wth->fh, mp2t->trailer_len, SEEK_CUR, err)) {
+ return FALSE;
+ }
}
- mp2t->offset += MP2T_SIZE + mp2t->trailer_len;
+ return TRUE;
+}
- /* XXX - relative, not absolute, time stamps */
- wth->phdr.presence_flags = WTAP_HAS_TS;
-
- /* It would be really cool to be able to configure the bitrate... */
- tmp = (MP2T_SIZE+mp2t->trailer_len) * 8;
- tmp *= 1000000000;
- tmp /= MP2T_QAM256_BITRATE;
-
- wth->phdr.ts.secs = mp2t->now.secs;
- wth->phdr.ts.nsecs = mp2t->now.nsecs;
- mp2t->now.nsecs += (guint32)tmp;
- if (1000000000 <= mp2t->now.nsecs) {
- mp2t->now.nsecs -= 1000000000;
- mp2t->now.secs++;
+static gboolean
+mp2t_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr,
+ Buffer *buf, int *err, gchar **err_info)
+{
+ mp2t_filetype_t *mp2t;
+
+ if (-1 == file_seek(wth->random_fh, seek_off, SEEK_SET, err)) {
+ return FALSE;
}
- wth->phdr.caplen = MP2T_SIZE;
- wth->phdr.len = MP2T_SIZE;
+ mp2t = (mp2t_filetype_t*) wth->priv;
+
+ if (!mp2t_read_packet(mp2t, wth->random_fh, seek_off, phdr, buf,
+ err, err_info)) {
+ if (*err == 0)
+ *err = WTAP_ERR_SHORT_READ;
+ return FALSE;
+ }
return TRUE;
}
+static guint64
+mp2t_read_pcr(guint8 *buffer)
+{
+ guint64 base;
+ guint64 ext;
+
+ base = pntoh40(buffer);
+ base >>= 7;
+
+ ext = pntoh16(&buffer[4]);
+ ext &= 0x01ff;
+
+ return (base * 300 + ext);
+}
+
static gboolean
-mp2t_seek_read(wtap *wth, gint64 seek_off,
- union wtap_pseudo_header *pseudo_header _U_, guint8 *pd, int length,
- int *err, gchar **err_info)
+mp2t_find_next_pcr(wtap *wth, guint8 trailer_len,
+ int *err, gchar **err_info, guint32 *idx, guint64 *pcr, guint16 *pid)
{
- if (-1 == file_seek(wth->random_fh, seek_off, SEEK_SET, err)) {
- return FALSE;
+ guint8 buffer[MP2T_SIZE+TRAILER_LEN_MAX];
+ gboolean found;
+ guint8 afc;
+ guint timeout = 0;
+
+ found = FALSE;
+ while (FALSE == found && timeout++ < SYNC_STEPS * SYNC_STEPS) {
+ (*idx)++;
+ if (!wtap_read_bytes_or_eof(
+ wth->fh, buffer, MP2T_SIZE+trailer_len, err, err_info)) {
+ /* Read error, short read, or EOF */
+ return FALSE;
+ }
+
+ if (MP2T_SYNC_BYTE != buffer[0]) {
+ continue;
+ }
+
+ /* Read out the AFC value. */
+ afc = 3 & (buffer[3] >> 4);
+ if (afc < 2) {
+ continue;
+ }
+
+ /* Check the length. */
+ if (buffer[4] < 7) {
+ continue;
+ }
+
+ /* Check that there is the PCR flag. */
+ if (0x10 != (0x10 & buffer[5])) {
+ continue;
+ }
+
+ /* We have a PCR value! */
+ *pcr = mp2t_read_pcr(&buffer[6]);
+ *pid = 0x01ff & pntoh16(&buffer[1]);
+ found = TRUE;
+ }
+
+ return found;
+}
+
+static wtap_open_return_val
+mp2t_bits_per_second(wtap *wth, guint32 first, guint8 trailer_len,
+ guint64 *bitrate, int *err, gchar **err_info)
+{
+ guint32 pn1, pn2;
+ guint64 pcr1, pcr2;
+ guint16 pid1, pid2;
+ guint32 idx;
+ guint64 pcr_delta, bits_passed;
+
+ /* Find the first PCR + PID.
+ * Then find another PCR in that PID.
+ * Take the difference and that's our bitrate.
+ * All the different PCRs in different PIDs 'should' be the same.
+ *
+ * XXX - is this assuming that the time stamps in the PCRs correspond
+ * to the time scale of the underlying transport stream?
+ */
+ idx = first;
+
+ if (!mp2t_find_next_pcr(wth, trailer_len, err, err_info, &idx, &pcr1, &pid1)) {
+ /* Read error, short read, or EOF */
+ if (*err == WTAP_ERR_SHORT_READ)
+ return WTAP_OPEN_NOT_MINE; /* not a full frame */
+ if (*err != 0)
+ return WTAP_OPEN_ERROR;
+
+ /* We don't have any PCRs, so we can't guess the bit rate.
+ * Default to something reasonable.
+ */
+ *bitrate = MP2T_QAM64_BITRATE;
+ return WTAP_OPEN_MINE;
+ }
+
+ pn1 = idx;
+ pn2 = pn1;
+
+ while (pn1 == pn2) {
+ if (!mp2t_find_next_pcr(wth, trailer_len, err, err_info, &idx, &pcr2, &pid2)) {
+ /* Read error, short read, or EOF */
+ if (*err == WTAP_ERR_SHORT_READ)
+ return WTAP_OPEN_NOT_MINE; /* not a full frame */
+ if (*err != 0)
+ return WTAP_OPEN_ERROR;
+
+ /* We don't have two PCRs for the same PID, so we can't guess
+ * the bit rate.
+ * Default to something reasonable.
+ */
+ *bitrate = MP2T_QAM64_BITRATE;
+ return WTAP_OPEN_MINE;
+ }
+
+ if (pid1 == pid2) {
+ pn2 = idx;
+ }
}
- return mp2t_read_data(pd, length, err, err_info, wth->random_fh);
+ if (pcr2 <= pcr1) {
+ /* The PCRs for that PID didn't go forward; treat that as an
+ * indication that this isn't an MPEG-2 TS.
+ */
+ return WTAP_OPEN_NOT_MINE;
+ }
+ pcr_delta = pcr2 - pcr1;
+ /* cast one of the factors to guint64
+ otherwise, the multiplication would use guint32 and could
+ overflow before the result is assigned to the guint64 bits_passed */
+ bits_passed = (guint64)MP2T_SIZE * (pn2 - pn1) * 8;
+
+ *bitrate = ((MP2T_PCR_CLOCK * bits_passed) / pcr_delta);
+ if (*bitrate == 0) {
+ /* pcr_delta < MP2T_PCR_CLOCK * bits_passed (pn2 != pn1,
+ * as that's the test for the loop above, so bits_passed
+ * is non-zero).
+ *
+ * That will produce a fractional bitrate, which turns
+ * into zero, causing a zero divide later.
+ *
+ * XXX - should we report this as "not ours"? A bitrate
+ * of less than 1 bit per second is not very useful for any
+ * form of audio/video, so presumably that's unlikely to
+ * be an MP2T file.
+ */
+ return WTAP_OPEN_ERROR;
+ }
+ return WTAP_OPEN_MINE;
}
-int
+wtap_open_return_val
mp2t_open(wtap *wth, int *err, gchar **err_info)
{
- int bytes_read;
guint8 buffer[MP2T_SIZE+TRAILER_LEN_MAX];
guint8 trailer_len = 0;
guint sync_steps = 0;
- int i;
- int first;
+ guint i;
+ guint32 first = 0;
mp2t_filetype_t *mp2t;
+ wtap_open_return_val status;
+ guint64 bitrate;
- errno = WTAP_ERR_CANT_READ;
- bytes_read = file_read(buffer, MP2T_SIZE, wth->fh);
-
- if (MP2T_SIZE != bytes_read) {
- *err = file_error(wth->fh, err_info);
- return (*err == 0) ? 0 : -1;
+ if (!wtap_read_bytes(wth->fh, buffer, MP2T_SIZE, err, err_info)) {
+ if (*err != WTAP_ERR_SHORT_READ)
+ return WTAP_OPEN_ERROR;
+ return WTAP_OPEN_NOT_MINE;
}
- first = -1;
for (i = 0; i < MP2T_SIZE; i++) {
if (MP2T_SYNC_BYTE == buffer[i]) {
first = i;
- break;
+ goto found;
}
}
- if (-1 == first) {
- return 0; /* wrong file type - not an mpeg2 ts file */
- }
+ /*
+ * No sync bytes found, so not an MPEG-2 Transport Stream file.
+ */
+ return WTAP_OPEN_NOT_MINE; /* wrong file type - not an mpeg2 ts file */
+found:
if (-1 == file_seek(wth->fh, first, SEEK_SET, err)) {
- return -1;
+ return WTAP_OPEN_ERROR;
}
+
/* read some packets and make sure they all start with a sync byte */
do {
- bytes_read = file_read(buffer, MP2T_SIZE+trailer_len, wth->fh);
- if (bytes_read < 0)
- return -1; /* read error */
- if (bytes_read < MP2T_SIZE+trailer_len)
+ if (!wtap_read_bytes(wth->fh, buffer, MP2T_SIZE+trailer_len, err, err_info)) {
+ if (*err != WTAP_ERR_SHORT_READ)
+ return WTAP_OPEN_ERROR; /* read error */
+ if(sync_steps<2) return WTAP_OPEN_NOT_MINE; /* wrong file type - not an mpeg2 ts file */
break; /* end of file, that's ok if we're still in sync */
-
+ }
if (buffer[0] == MP2T_SYNC_BYTE) {
sync_steps++;
}
/* if we've already detected a trailer field, we must remain in sync
another mismatch means we have no mpeg2 ts file */
if (trailer_len>0)
- return 0;
+ return WTAP_OPEN_NOT_MINE;
/* check if a trailer is appended to the packet */
for (i=0; i<TRAILER_LEN_MAX; i++) {
if (buffer[i] == MP2T_SYNC_BYTE) {
trailer_len = i;
if (-1 == file_seek(wth->fh, first, SEEK_SET, err)) {
- return -1;
+ return WTAP_OPEN_ERROR;
}
sync_steps = 0;
break;
}
/* no sync byte found in the vicinity, this is no mpeg2 ts file */
if (i==TRAILER_LEN_MAX)
- return 0;
+ return WTAP_OPEN_NOT_MINE;
}
} while (sync_steps < SYNC_STEPS);
if (-1 == file_seek(wth->fh, first, SEEK_SET, err)) {
- return -1;
+ return WTAP_OPEN_ERROR;
+ }
+
+ /* Ensure there is a valid bitrate */
+ status = mp2t_bits_per_second(wth, first, trailer_len,
+ &bitrate, err, err_info);
+ if (status != WTAP_OPEN_MINE) {
+ return status;
+ }
+
+ if (-1 == file_seek(wth->fh, first, SEEK_SET, err)) {
+ return WTAP_OPEN_ERROR;
}
- wth->file_type = WTAP_FILE_MPEG_2_TS;
+ wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MPEG_2_TS;
wth->file_encap = WTAP_ENCAP_MPEG_2_TS;
- wth->tsprecision = WTAP_FILE_TSPREC_NSEC;
+ wth->file_tsprec = WTAP_TSPREC_NSEC;
wth->subtype_read = mp2t_read;
wth->subtype_seek_read = mp2t_seek_read;
wth->snapshot_length = 0;
mp2t = (mp2t_filetype_t*) g_malloc(sizeof(mp2t_filetype_t));
- if (NULL == mp2t) {
- return -1;
- }
wth->priv = mp2t;
- mp2t->offset = (guint32) first;
- mp2t->now.secs = 0;
- mp2t->now.nsecs = 0;
+ mp2t->start_offset = first;
mp2t->trailer_len = trailer_len;
+ mp2t->bitrate = bitrate;
- return 1;
+ return WTAP_OPEN_MINE;
}
+
+/*
+ * Editor modelines - http://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:
+ */
git.samba.org / metze / wireshark / wip.git / blobdiff