/**

 * 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.

 */

#include <freerdp/config.h>

#include "tpdu.h"

#include "tpkt.h"

#include <winpr/wlog.h>

#define TAG FREERDP_TAG("core.tpkt")

/**

 * 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.

 *

 * @param s A stream to read from

 *

 * @return \b TRUE for success, \b FALSE otherwise

 */

int tpkt_verify_header(wStream* s)

{

  BYTE version = 0;

  if (!Stream_CheckAndLogRequiredLength(TAG, s, 1))

    return -1;

  Stream_Peek_UINT8(s, version);

  if (version == 3)

    return 1;

  else

    return 0;

}

/**

 * Read a TPKT header.

 *

 * @param s A stream to read from

 * @param length A pointer to the result, must not be NULL

 *

 * @return \b TRUE for success, \b FALSE otherwise

 */

BOOL tpkt_read_header(wStream* s, UINT16* length)

{

  BYTE version = 0;

  if (!Stream_CheckAndLogRequiredLength(TAG, s, 1))

    return FALSE;

  Stream_Peek_UINT8(s, version);

  if (version == 3)

  {

    UINT16 len = 0;

    if (!Stream_CheckAndLogRequiredLength(TAG, s, 4))

      return FALSE;

    Stream_Seek(s, 2);

    Stream_Read_UINT16_BE(s, len);

    /* ITU-T Rec. T.123 8 Packet header to delimit data units in an octet stream */

    if (len < 7)

    {

      WLog_ERR(TAG, "TPKT header too short, require minimum of 7 bytes, got %" PRId16, len);

      return FALSE;

    }

    if (!Stream_CheckAndLogRequiredLength(TAG, s, len - 4))

    {

      WLog_ERR(TAG, "TPKT header length %" PRIu16 ", but received less", len);

      return FALSE;

    }

    *length = len;

  }

  else

  {

    /* not a TPKT header */

    *length = 0;

  }

  return TRUE;

}

BOOL tpkt_ensure_stream_consumed_(wStream* s, size_t length, const char* fkt)

{

  if (length > UINT16_MAX)

  {

    WLog_ERR(TAG, "[%s] length %" PRIuz " > %" PRIu16, fkt, length, UINT16_MAX);

    return FALSE;

  }

  size_t rem = Stream_GetRemainingLength(s);

  if (rem > 0)

  {

    WLog_ERR(TAG,

             "[%s] Received invalid TPKT header length %" PRIu16 ", %" PRIdz " bytes too long!",

             fkt, length, rem);

    return FALSE;

  }

  return TRUE;

}

/**

 * Write a TPKT header.

 *

 * @param s A stream to write to

 * @param length The value to write

 *

 * @return \b TRUE for success, \b FALSE otherwise

 */

BOOL tpkt_write_header(wStream* s, size_t length)

{

  if (!Stream_CheckAndLogRequiredCapacity(TAG, (s), 4))

    return FALSE;

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

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

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

  return TRUE;

}