/**

 * FreeRDP: A Remote Desktop Protocol Implementation

 * Transport Packets (TPKTs)

 *

 * Copyright 2011 Marc-Andre Moreau <marcandre.moreau@gmail.com>

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "tpdu.h"

#include "tpkt.h"

/**

 * TPKTs are defined in:

 *

 * http://tools.ietf.org/html/rfc1006/

 * RFC 1006 - ISO Transport Service on top of the TCP

 *

 * http://www.itu.int/rec/T-REC-T.123/

 * ITU-T T.123 (01/2007) - Network-specific data protocol stacks for multimedia conferencing

 *

 *       TPKT Header

 *  ____________________   byte

 * |                    |

 * |     3 (version)    |   1

 * |____________________|

 * |                    |

 * |      Reserved      |   2

 * |____________________|

 * |                    |

 * |    Length (MSB)    |   3

 * |____________________|

 * |                    |

 * |    Length (LSB)    |   4

 * |____________________|

 * |                    |

 * |     X.224 TPDU     |   5 - ?

 *          ....

 *

 * A TPKT header is of fixed length 4, and the following X.224 TPDU is at least three bytes long.

 * Therefore, the minimum TPKT length is 7, and the maximum TPKT length is 65535. Because the TPKT

 * length includes the TPKT header (4 bytes), the maximum X.224 TPDU length is 65531.

 */

/**

 * Verify if a packet has valid TPKT header.\n

 * @param s

 * @return BOOL

 */

BOOL tpkt_verify_header(wStream* s)

{

	BYTE version;

	Stream_Peek_UINT8(s, version);

	if (version == 3)

		return TRUE;

	else

		return FALSE;

}

/**

 * Read a TPKT header.\n

 * @param s

 * @param length

 * @return success

 */

BOOL tpkt_read_header(wStream* s, UINT16* length)

{

	BYTE version;

	if (Stream_GetRemainingLength(s) < 1)

		return FALSE;

	Stream_Peek_UINT8(s, version);

	if (version == 3)

	{

		UINT16 len;

		if (Stream_GetRemainingLength(s) < 4)

			return FALSE;

		Stream_Seek(s, 2);

		Stream_Read_UINT16_BE(s, len);

		if (len < 4)

			return FALSE;

		*length = len;

	}

	else

	{

		/* not a TPKT header */

		*length = 0;

	}

	return TRUE;

}

/**

 * Write a TPKT header.\n

 * @param s

 * @param length

 */

void tpkt_write_header(wStream* s, UINT16 length)

{

	Stream_Write_UINT8(s, 3); /* version */

	Stream_Write_UINT8(s, 0); /* reserved */

	Stream_Write_UINT16_BE(s, length); /* length */

}