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Diffstat (limited to 'libfreerdp/core/tpkt.c')
| -rw-r--r-- | libfreerdp/core/tpkt.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/libfreerdp/core/tpkt.c b/libfreerdp/core/tpkt.c new file mode 100644 index 0000000..2e84c66 --- /dev/null +++ b/libfreerdp/core/tpkt.c @@ -0,0 +1,171 @@ +/** + * 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, UINT16 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; +} |