mirror of https://github.com/FreeRDP/FreeRDP
170 lines
3.5 KiB
C
170 lines
3.5 KiB
C
/**
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* FreeRDP: A Remote Desktop Protocol Client
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* X.224 Transport Protocol Data Units (TPDUs)
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*
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* Copyright 2011 Marc-Andre Moreau <marcandre.moreau@gmail.com>
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdio.h>
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#include "tpdu.h"
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/**
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* TPDUs are defined in:
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*
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* http://www.itu.int/rec/T-REC-X.224-199511-I/
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* X.224: Information technology - Open Systems Interconnection - Protocol for providing the connection-mode transport service
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*
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* RDP uses only TPDUs of class 0, the "simple class" defined in section 8 of X.224
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*
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* TPDU Header
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* ____________________ byte
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* | |
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* | LI | 1
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* |____________________|
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* | |
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* | Code | 2
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* |____________________|
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* | |
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* | | 3
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* |_______DST-REF______|
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* | |
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* | | 4
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* |____________________|
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* | |
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* | | 5
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* |_______SRC-REF______|
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* | |
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* | | 6
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* |____________________|
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* | |
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* | Class | 7
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* |____________________|
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* | ... |
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*/
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/**
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* Read TPDU header.
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* @param s stream
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* @param code variable pointer to receive TPDU code
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* @return TPDU length indicator (LI)
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*/
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uint8
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tpdu_read_header(STREAM* s, uint8* code)
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{
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uint8 li;
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stream_read_uint8(s, li); /* LI */
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stream_read_uint8(s, *code); /* Code */
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/* DST-REF (2 bytes) */
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/* SRC-REF (2 bytes) */
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/* Class 0 (1 byte) */
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stream_seek(s, 5);
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if (*code == X224_TPDU_DATA)
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{
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/* EOT (1 byte) */
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stream_seek(s, 1);
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}
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return li;
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}
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/**
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* Write TDPU header.
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* @param s stream
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* @param length length
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* @param code TPDU code
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*/
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void
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tpdu_write_header(STREAM* s, uint16 length, uint8 code)
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{
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stream_write_uint8(s, length); /* LI */
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stream_write_uint8(s, code); /* code */
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if (code == X224_TPDU_DATA)
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{
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stream_write_uint8(s, 0x80); /* EOT */
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}
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else
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{
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stream_write_uint16(s, 0); /* DST-REF */
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stream_write_uint16(s, 0); /* SRC-REF */
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stream_write_uint8(s, 0); /* Class 0 */
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}
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}
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/**
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* Write Connection Request TPDU.
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* @param s stream
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* @param length TPDU length
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*/
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void
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tpdu_write_connection_request(STREAM* s, uint16 length)
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{
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tpdu_write_header(s, length, X224_TPDU_CONNECTION_REQUEST);
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}
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/**
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* Read Connection Confirm TPDU.
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* @param s stream
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* @return length indicator (LI)
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*/
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uint8
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tpdu_read_connection_confirm(STREAM* s)
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{
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uint8 li;
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uint8 code;
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li = tpdu_read_header(s, &code);
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if (code != X224_TPDU_CONNECTION_CONFIRM)
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{
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printf("Error: expected X224_TPDU_CONNECTION_CONFIRM\n");
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return 0;
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}
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return li;
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}
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/**
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* Write Disconnect Request TPDU.
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* @param s stream
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* @param length TPDU length
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*/
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void
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tpdu_write_disconnect_request(STREAM* s, uint16 length)
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{
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tpdu_write_header(s, length, X224_TPDU_DISCONNECT_REQUEST);
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}
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/**
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* Write Data TPDU.
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* @param s stream
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* @param length TPDU length
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*/
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void
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tpdu_write_data(STREAM* s, uint16 length)
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{
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tpdu_write_header(s, length, X224_TPDU_DATA);
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}
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