166 lines
3.9 KiB
C
166 lines
3.9 KiB
C
/**
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* FreeRDP: A Remote Desktop Protocol Implementation
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* Transport Packets (TPKTs)
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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 <freerdp/config.h>
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#include "tpdu.h"
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#include "tpkt.h"
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#include <winpr/wlog.h>
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#define TAG FREERDP_TAG("core.tpkt")
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/**
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* TPKTs are defined in:
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*
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* http://tools.ietf.org/html/rfc1006/
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* RFC 1006 - ISO Transport Service on top of the TCP
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*
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* http://www.itu.int/rec/T-REC-T.123/
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* ITU-T T.123 (01/2007) - Network-specific data protocol stacks for multimedia conferencing
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*
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* TPKT Header
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* ____________________ byte
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* | |
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* | 3 (version) | 1
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* |____________________|
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* | |
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* | Reserved | 2
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* |____________________|
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* | |
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* | Length (MSB) | 3
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* |____________________|
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* | |
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* | Length (LSB) | 4
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* |____________________|
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* | |
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* | X.224 TPDU | 5 - ?
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* ....
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*
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* A TPKT header is of fixed length 4, and the following X.224 TPDU is at least three bytes long.
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* Therefore, the minimum TPKT length is 7, and the maximum TPKT length is 65535. Because the TPKT
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* length includes the TPKT header (4 bytes), the maximum X.224 TPDU length is 65531.
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*/
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/**
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* Verify if a packet has valid TPKT header.
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*
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* @param s A stream to read from
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*
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* @return \b TRUE for success, \b FALSE otherwise
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*/
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int tpkt_verify_header(wStream* s)
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{
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BYTE version;
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if (!Stream_CheckAndLogRequiredLength(TAG, s, 1))
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return -1;
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Stream_Peek_UINT8(s, version);
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if (version == 3)
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return 1;
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else
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return 0;
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}
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/**
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* Read a TPKT header.
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*
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* @param s A stream to read from
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* @param length A pointer to the result, must not be NULL
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*
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* @return \b TRUE for success, \b FALSE otherwise
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*/
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BOOL tpkt_read_header(wStream* s, UINT16* length)
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{
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BYTE version;
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if (!Stream_CheckAndLogRequiredLength(TAG, s, 1))
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return FALSE;
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Stream_Peek_UINT8(s, version);
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if (version == 3)
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{
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UINT16 len;
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if (!Stream_CheckAndLogRequiredLength(TAG, s, 4))
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return FALSE;
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Stream_Seek(s, 2);
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Stream_Read_UINT16_BE(s, len);
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/* ITU-T Rec. T.123 8 Packet header to delimit data units in an octet stream */
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if (len < 7)
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{
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WLog_ERR(TAG, "TPKT header too short, require minimum of 7 bytes, got %" PRId16, len);
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return FALSE;
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}
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if (!Stream_CheckAndLogRequiredLength(TAG, s, len - 4))
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{
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WLog_ERR(TAG, "TPKT header length %" PRIu16 ", but received less", len);
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return FALSE;
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}
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*length = len;
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}
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else
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{
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/* not a TPKT header */
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*length = 0;
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}
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return TRUE;
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}
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BOOL tpkt_ensure_stream_consumed_(wStream* s, UINT16 length, const char* fkt)
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{
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size_t rem = Stream_GetRemainingLength(s);
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if (rem > 0)
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{
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WLog_ERR(TAG,
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"[%s] Received invalid TPKT header length %" PRIu16 ", %" PRIdz " bytes too long!",
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fkt, length, rem);
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return FALSE;
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}
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return TRUE;
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}
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/**
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* Write a TPKT header.
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*
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* @param s A stream to write to
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* @param length The value to write
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*
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* @return \b TRUE for success, \b FALSE otherwise
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*/
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BOOL tpkt_write_header(wStream* s, UINT16 length)
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{
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if (!Stream_CheckAndLogRequiredCapacity(TAG, (s), 4))
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return FALSE;
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Stream_Write_UINT8(s, 3); /* version */
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Stream_Write_UINT8(s, 0); /* reserved */
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Stream_Write_UINT16_BE(s, length); /* length */
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return TRUE;
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}
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