gstreamer/libs/gst/dataprotocol/dataprotocol.c

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/* GStreamer
* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
* Copyright (C) <2004> Thomas Vander Stichele <thomas at apestaart dot org>
*
* dataprotocol.c: Functions implementing the GStreamer Data Protocol
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/gst.h>
#include <gst/dataprotocol/dataprotocol.h>
#include <glib/gprintf.h> /* g_sprintf */
#include <string.h> /* strlen */
#include "dp-private.h"
/* debug category */
GST_DEBUG_CATEGORY (data_protocol_debug);
#define GST_CAT_DEFAULT data_protocol_debug
/* calculate a CCITT 16 bit CRC check value for a given byte array */
/*
* this code snippet is adapted from a web page I found
* it is identical except for cleanups, and a final XOR with 0xffff
* as outlined in the uecp spec
*
* XMODEM x^16 + x^12 + x^5 + 1
*/
#define POLY 0x1021
#define CRC_INIT 0xFFFF
static guint16
gst_dp_crc (const guint8 * buffer, register guint length)
{
static gboolean initialized = FALSE;
static guint16 crc_table[256];
guint16 crc_register;
unsigned long i, j, k;
if (!initialized) {
for (i = 0; i < 256; i++) {
j = i << 8;
for (k = 8; k--;) {
j = j & 0x8000 ? (j << 1) ^ POLY : j << 1;
}
crc_table[i] = (guint16) j;
}
initialized = TRUE;
}
crc_register = CRC_INIT; /* always init register */
/* calc CRC */
for (; length--;) {
crc_register = (guint16) ((crc_register << 8) ^
crc_table[((crc_register >> 8) & 0x00ff) ^ *buffer++]);
}
return (0xffff ^ crc_register);
}
/* debugging function; dumps byte array values per 8 bytes */
/* FIXME: would be nice to merge this with gst_util_dump_mem () */
void
gst_dp_dump_byte_array (guint8 * array, guint length)
{
int i;
int n = 8; /* number of bytes per line */
gchar *line = g_malloc (3 * n + 1);
GST_LOG ("dumping byte array of length %d", length);
for (i = 0; i < length; ++i) {
g_sprintf (line + 3 * (i % n), "%02x ", array[i]);
if (i % n == (n - 1)) {
GST_LOG ("%03d: %s", i - (n - 1), line);
}
}
if (i % n != 0) {
GST_LOG ("%03d: %s", (i / n) * n, line);
}
g_free (line);
}
/**
* gst_dp_init:
*
* Initialize GStreamer Data Protocol library.
*
* Should be called before using these functions; either from source linking
* to this source file or from plugin_init.
*/
void
gst_dp_init (void)
{
static gboolean _gst_dp_initialized = FALSE;
if (_gst_dp_initialized)
return;
_gst_dp_initialized = TRUE;
GST_DEBUG_CATEGORY_INIT (data_protocol_debug, "gdp", 0,
"GStreamer Data Protocol");
}
/*** PUBLIC FUNCTIONS ***/
/**
* gst_dp_header_payload_length:
* @header: the byte header of the packet array
*
* Returns: the length of the payload this header describes.
*/
guint32
gst_dp_header_payload_length (const guint8 * header)
{
return GST_DP_HEADER_PAYLOAD_LENGTH (header);
}
/**
* gst_dp_header_payload_type:
* @header: the byte header of the packet array
*
* Returns: the #GstDPPayloadType the payload this header describes.
*/
GstDPPayloadType
gst_dp_header_payload_type (const guint8 * header)
{
return GST_DP_HEADER_PAYLOAD_TYPE (header);
}
/**
* gst_dp_header_from_buffer:
* @buffer: a #GstBuffer to create a header for
* @flags: the #GDPHeaderFlags to create the header with
* @length: a guint pointer to store the header length in
* @header: a guint8 * pointer to store a newly allocated header byte array in
*
* Creates a GDP header from the given buffer.
*
* Returns: %TRUE if the header was successfully created.
*/
gboolean
gst_dp_header_from_buffer (const GstBuffer * buffer, GstDPHeaderFlag flags,
guint * length, guint8 ** header)
{
guint8 *h;
guint16 crc;
guint16 flags_mask;
g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
g_return_val_if_fail (GST_BUFFER_REFCOUNT_VALUE (buffer) > 0, FALSE);
g_return_val_if_fail (header, FALSE);
*length = GST_DP_HEADER_LENGTH;
h = g_malloc (GST_DP_HEADER_LENGTH);
/* version, flags, type */
h[0] = (guint8) GST_DP_VERSION_MAJOR;
h[1] = (guint8) GST_DP_VERSION_MINOR;
h[2] = (guint8) flags;
h[3] = GST_DP_PAYLOAD_BUFFER;
/* buffer properties */
GST_WRITE_UINT32_BE (h + 4, GST_BUFFER_SIZE (buffer));
GST_WRITE_UINT64_BE (h + 8, GST_BUFFER_TIMESTAMP (buffer));
GST_WRITE_UINT64_BE (h + 16, GST_BUFFER_DURATION (buffer));
GST_WRITE_UINT64_BE (h + 24, GST_BUFFER_OFFSET (buffer));
GST_WRITE_UINT64_BE (h + 32, GST_BUFFER_OFFSET_END (buffer));
/* data flags */
/* we only copy KEY_UNIT,DELTA_UNIT and IN_CAPS flags */
flags_mask = GST_DATA_FLAG_SHIFT (GST_BUFFER_PREROLL) |
GST_DATA_FLAG_SHIFT (GST_BUFFER_IN_CAPS) |
GST_DATA_FLAG_SHIFT (GST_BUFFER_DELTA_UNIT);
GST_WRITE_UINT16_BE (h + 40, GST_BUFFER_FLAGS (buffer) & flags_mask);
/* ABI padding */
GST_WRITE_UINT16_BE (h + 42, (guint64) 0);
GST_WRITE_UINT32_BE (h + 44, (guint64) 0);
GST_WRITE_UINT64_BE (h + 48, (guint64) 0);
/* CRC */
crc = 0;
if (flags & GST_DP_HEADER_FLAG_CRC_HEADER) {
/* we don't crc the last four bytes of the header since they are crc's */
crc = gst_dp_crc (h, 56);
}
GST_WRITE_UINT16_BE (h + 56, crc);
crc = 0;
if (flags & GST_DP_HEADER_FLAG_CRC_PAYLOAD) {
crc = gst_dp_crc (GST_BUFFER_DATA (buffer), GST_BUFFER_SIZE (buffer));
}
GST_WRITE_UINT16_BE (h + 58, crc);
GST_LOG ("created header from buffer:");
gst_dp_dump_byte_array (h, GST_DP_HEADER_LENGTH);
*header = h;
return TRUE;
}
/**
* gst_dp_packet_from_caps:
* @caps: a #GstCaps to create a packet for
* @flags: the #GDPHeaderFlags to create the header with
* @length: a guint pointer to store the header length in
* @header: a guint8 pointer to store a newly allocated header byte array in
* @payload: a guint8 pointer to store a newly allocated payload byte array in
*
* Creates a GDP packet from the given caps.
*
* Returns: %TRUE if the packet was successfully created.
*/
gboolean
gst_dp_packet_from_caps (const GstCaps * caps, GstDPHeaderFlag flags,
guint * length, guint8 ** header, guint8 ** payload)
{
guint8 *h;
guint16 crc;
gchar *string;
/* FIXME: GST_IS_CAPS doesn't work
g_return_val_if_fail (GST_IS_CAPS (caps), FALSE); */
g_return_val_if_fail (caps, FALSE);
g_return_val_if_fail (header, FALSE);
g_return_val_if_fail (payload, FALSE);
*length = GST_DP_HEADER_LENGTH;
h = g_malloc (GST_DP_HEADER_LENGTH);
string = gst_caps_to_string (caps);
/* version, flags, type */
h[0] = (guint8) GST_DP_VERSION_MAJOR;
h[1] = (guint8) GST_DP_VERSION_MINOR;
h[2] = (guint8) flags;
h[3] = GST_DP_PAYLOAD_CAPS;
/* buffer properties */
GST_WRITE_UINT32_BE (h + 4, strlen (string) + 1); /* include trailing 0 */
GST_WRITE_UINT64_BE (h + 8, (guint64) 0);
GST_WRITE_UINT64_BE (h + 16, (guint64) 0);
GST_WRITE_UINT64_BE (h + 24, (guint64) 0);
GST_WRITE_UINT64_BE (h + 32, (guint64) 0);
/* ABI padding */
GST_WRITE_UINT64_BE (h + 40, (guint64) 0);
GST_WRITE_UINT64_BE (h + 48, (guint64) 0);
/* CRC */
crc = 0;
if (flags & GST_DP_HEADER_FLAG_CRC_HEADER) {
crc = gst_dp_crc (h, 56);
}
GST_WRITE_UINT16_BE (h + 56, crc);
crc = 0;
if (flags & GST_DP_HEADER_FLAG_CRC_PAYLOAD) {
crc = gst_dp_crc (string, strlen (string) + 1);
}
GST_WRITE_UINT16_BE (h + 58, crc);
GST_LOG ("created header from caps:");
gst_dp_dump_byte_array (h, GST_DP_HEADER_LENGTH);
*header = h;
*payload = string;
return TRUE;
}
/**
* gst_dp_packet_from_event:
* @event: a #GstEvent to create a packet for
* @flags: the #GDPHeaderFlags to create the header with
* @length: a guint pointer to store the header length in
* @header: a guint8 pointer to store a newly allocated header byte array in
* @payload: a guint8 pointer to store a newly allocated payload byte array in
*
* Creates a GDP packet from the given event.
*
* Returns: %TRUE if the packet was successfully created.
*/
gboolean
gst_dp_packet_from_event (const GstEvent * event, GstDPHeaderFlag flags,
guint * length, guint8 ** header, guint8 ** payload)
{
guint8 *h;
guint16 crc;
guint pl_length; /* length of payload */
g_return_val_if_fail (event, FALSE);
g_return_val_if_fail (GST_IS_EVENT (event), FALSE);
g_return_val_if_fail (header, FALSE);
g_return_val_if_fail (payload, FALSE);
*length = GST_DP_HEADER_LENGTH;
h = g_malloc0 (GST_DP_HEADER_LENGTH);
/* first construct payload, since we need the length */
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_UNKNOWN:
g_warning ("Unknown event, ignoring");
*length = 0;
g_free (h);
return FALSE;
case GST_EVENT_EOS:
case GST_EVENT_FLUSH:
case GST_EVENT_DISCONTINUOUS:
GST_WRITE_UINT64_BE (h + 8, GST_EVENT_TIMESTAMP (event));
pl_length = 0;
*payload = NULL;
break;
case GST_EVENT_SEEK:
pl_length = 4 + 8 + 8 + 4;
*payload = g_malloc0 (pl_length);
GST_WRITE_UINT32_BE (*payload, (guint32) GST_EVENT_SEEK_TYPE (event));
GST_WRITE_UINT64_BE (*payload + 4,
(guint64) GST_EVENT_SEEK_OFFSET (event));
GST_WRITE_UINT64_BE (*payload + 12,
(guint64) GST_EVENT_SEEK_ENDOFFSET (event));
GST_WRITE_UINT32_BE (*payload + 20,
(guint32) GST_EVENT_SEEK_ACCURACY (event));
break;
case GST_EVENT_QOS:
case GST_EVENT_SIZE:
case GST_EVENT_RATE:
case GST_EVENT_NAVIGATION:
case GST_EVENT_TAG:
g_warning ("Unhandled event type %d, ignoring", GST_EVENT_TYPE (event));
return FALSE;
default:
g_warning ("Unknown event type %d, ignoring", GST_EVENT_TYPE (event));
*length = 0;
g_free (h);
return FALSE;
}
/* version, flags, type */
h[0] = (guint8) GST_DP_VERSION_MAJOR;
h[1] = (guint8) GST_DP_VERSION_MINOR;
h[2] = (guint8) flags;
h[3] = GST_DP_PAYLOAD_EVENT_NONE + GST_EVENT_TYPE (event);
/* length */
GST_WRITE_UINT32_BE (h + 4, (guint32) pl_length);
/* timestamp */
GST_WRITE_UINT64_BE (h + 8, GST_EVENT_TIMESTAMP (event));
/* ABI padding */
GST_WRITE_UINT64_BE (h + 40, (guint64) 0);
GST_WRITE_UINT64_BE (h + 48, (guint64) 0);
/* CRC */
crc = 0;
if (flags & GST_DP_HEADER_FLAG_CRC_HEADER) {
crc = gst_dp_crc (h, 56);
}
GST_WRITE_UINT16_BE (h + 56, crc);
crc = 0;
/* events can have a NULL payload */
if (*payload && flags & GST_DP_HEADER_FLAG_CRC_PAYLOAD) {
crc = gst_dp_crc (*payload, strlen (*payload) + 1);
}
GST_WRITE_UINT16_BE (h + 58, crc);
GST_LOG ("created header from event:");
gst_dp_dump_byte_array (h, GST_DP_HEADER_LENGTH);
*header = h;
return TRUE;
}
/**
* gst_dp_buffer_from_header:
* @header_length: the length of the packet header
* @header: the byte array of the packet header
*
* Creates a newly allocated #GstBuffer from the given header.
* The buffer data needs to be copied into it before validating.
*
* Use this function if you want to pre-allocate a buffer based on the
* packet header to read the packet payload in to.
*
* Returns: %TRUE if the buffer was successfully created.
*/
GstBuffer *
gst_dp_buffer_from_header (guint header_length, const guint8 * header)
{
GstBuffer *buffer;
g_return_val_if_fail (GST_DP_HEADER_PAYLOAD_TYPE (header) ==
GST_DP_PAYLOAD_BUFFER, FALSE);
buffer =
gst_buffer_new_and_alloc ((guint) GST_DP_HEADER_PAYLOAD_LENGTH (header));
GST_BUFFER_TIMESTAMP (buffer) = GST_DP_HEADER_TIMESTAMP (header);
GST_BUFFER_DURATION (buffer) = GST_DP_HEADER_DURATION (header);
GST_BUFFER_OFFSET (buffer) = GST_DP_HEADER_OFFSET (header);
GST_BUFFER_OFFSET_END (buffer) = GST_DP_HEADER_OFFSET_END (header);
GST_BUFFER_FLAGS (buffer) = GST_DP_HEADER_BUFFER_FLAGS (header);
return buffer;
}
/**
* gst_dp_caps_from_packet:
* @header_length: the length of the packet header
* @header: the byte array of the packet header
* @payload: the byte array of the packet payload
*
* Creates a newly allocated #GstCaps from the given packet.
*
* Returns: %TRUE if the caps was successfully created.
*/
GstCaps *
gst_dp_caps_from_packet (guint header_length, const guint8 * header,
const guint8 * payload)
{
GstCaps *caps;
const gchar *string;
g_return_val_if_fail (header, FALSE);
g_return_val_if_fail (payload, FALSE);
g_return_val_if_fail (GST_DP_HEADER_PAYLOAD_TYPE (header) ==
GST_DP_PAYLOAD_CAPS, FALSE);
string = payload;
caps = gst_caps_from_string (string);
return caps;
}
/**
* gst_dp_event_from_packet:
* @header_length: the length of the packet header
* @header: the byte array of the packet header
* @payload: the byte array of the packet payload
*
* Creates a newly allocated #GstEvent from the given packet.
*
* Returns: %TRUE if the event was successfully created.
*/
GstEvent *
gst_dp_event_from_packet (guint header_length, const guint8 * header,
const guint8 * payload)
{
GstEvent *event = NULL;
GstEventType type;
g_return_val_if_fail (header, FALSE);
/* payload can be NULL, e.g. for an EOS event */
type = GST_DP_HEADER_PAYLOAD_TYPE (header) - GST_DP_PAYLOAD_EVENT_NONE;
switch (type) {
case GST_EVENT_UNKNOWN:
g_warning ("Unknown event, ignoring");
return FALSE;
case GST_EVENT_EOS:
case GST_EVENT_FLUSH:
case GST_EVENT_DISCONTINUOUS:
event = gst_event_new (type);
GST_EVENT_TIMESTAMP (event) = GST_DP_HEADER_TIMESTAMP (header);
break;
case GST_EVENT_SEEK:
{
GstSeekType type;
gint64 offset, endoffset;
GstSeekAccuracy accuracy;
type = (GstSeekType) GST_READ_UINT32_BE (payload);
offset = (gint64) GST_READ_UINT64_BE (payload + 4);
endoffset = (gint64) GST_READ_UINT64_BE (payload + 12);
accuracy = (GstSeekAccuracy) GST_READ_UINT32_BE (payload + 20);
event = gst_event_new_segment_seek (type, offset, endoffset);
GST_EVENT_TIMESTAMP (event) = GST_DP_HEADER_TIMESTAMP (header);
GST_EVENT_SEEK_ACCURACY (event) = accuracy;
break;
}
case GST_EVENT_QOS:
case GST_EVENT_SIZE:
case GST_EVENT_RATE:
case GST_EVENT_NAVIGATION:
case GST_EVENT_TAG:
g_warning ("Unhandled event type %d, ignoring", GST_EVENT_TYPE (event));
return FALSE;
default:
g_warning ("Unknown event type %d, ignoring", GST_EVENT_TYPE (event));
return FALSE;
}
return event;
}
/**
* gst_dp_validate_header:
* @header_length: the length of the packet header
* @header: the byte array of the packet header
*
* Validates the given packet header by checking the CRC checksum.
*
* Returns: %TRUE if the CRC matches, or no CRC checksum is present.
*/
gboolean
gst_dp_validate_header (guint header_length, const guint8 * header)
{
guint16 crc_read, crc_calculated;
if (!(GST_DP_HEADER_FLAGS (header) & GST_DP_HEADER_FLAG_CRC_HEADER))
return TRUE;
crc_read = GST_DP_HEADER_CRC_HEADER (header);
/* don't included the last two crc fields for the crc check */
crc_calculated = gst_dp_crc (header, header_length - 4);
if (crc_read != crc_calculated) {
GST_WARNING ("header crc mismatch: read %02x, calculated %02x", crc_read,
crc_calculated);
return FALSE;
}
GST_LOG ("header crc validation: %02x", crc_read);
return TRUE;
}
/**
* gst_dp_validate_payload:
* @header_length: the length of the packet header
* @header: the byte array of the packet header
* @payload: the byte array of the packet payload
*
* Validates the given packet payload using the given packet header
* by checking the CRC checksum.
*
* Returns: %TRUE if the CRC matches, or no CRC checksum is present.
*/
gboolean
gst_dp_validate_payload (guint header_length, const guint8 * header,
const guint8 * payload)
{
guint16 crc_read, crc_calculated;
if (!(GST_DP_HEADER_FLAGS (header) & GST_DP_HEADER_FLAG_CRC_PAYLOAD))
return TRUE;
crc_read = GST_DP_HEADER_CRC_PAYLOAD (header);
crc_calculated = gst_dp_crc (payload, GST_DP_HEADER_PAYLOAD_LENGTH (header));
if (crc_read != crc_calculated) {
GST_WARNING ("payload crc mismatch: read %02x, calculated %02x", crc_read,
crc_calculated);
return FALSE;
}
GST_LOG ("payload crc validation: %02x", crc_read);
return TRUE;
}
/**
* gst_dp_validate_packet:
* @header_length: the length of the packet header
* @header: the byte array of the packet header
* @payload: the byte array of the packet payload
*
* Validates the given packet by checking version information and checksums.
*
* Returns: %TRUE if the packet validates.
*/
gboolean
gst_dp_validate_packet (guint header_length, const guint8 * header,
const guint8 * payload)
{
if (!gst_dp_validate_header (header_length, header))
return FALSE;
if (!gst_dp_validate_payload (header_length, header, payload))
return FALSE;
return TRUE;
}
/*** PLUGIN STUFF ***/
static gboolean
plugin_init (GstPlugin * plugin)
{
gst_dp_init ();
return TRUE;
}
GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
GST_VERSION_MINOR,
"gstdataprotocol",
"a data protocol to serialize buffers, caps and events",
plugin_init, VERSION, GST_LICENSE, GST_PACKAGE, GST_ORIGIN)