FreeRDP/libfreerdp-core/tpkt.c
2011-07-02 17:10:10 -04:00

85 lines
2.1 KiB
C

/**
* FreeRDP: A Remote Desktop Protocol Client
* 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 "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.
*/
uint16
tpkt_read_header(STREAM* s)
{
uint8 version;
uint16 length;
stream_peek_uint8(s, version);
if (version == 3)
{
stream_seek(s, 2);
stream_read_uint16(s, length);
}
else
{
/* not a TPKT header */
length = 0;
}
return length;
}
void
tpkt_write_header(STREAM* s, int length)
{
stream_write_uint8(s, 3); /* version */
stream_write_uint8(s, 8); /* reserved */
stream_write_uint16(s, length); /* length */
}