libfreerdp-core: add Fast Path header parsing.

libfreerdp-core/CMakeLists.txt

@@ -72,6 +72,8 @@ set(LIBFREERDP_CORE_SRCS
 	tpdu.h
 	tpkt.c
 	tpkt.h
+	fastpath.c
+	fastpath.h
 	transport.c
 	transport.h
 	update.c

libfreerdp-core/fastpath.c

@@ -0,0 +1,65 @@
+/**
+ * FreeRDP: A Remote Desktop Protocol Client
+ * Fast Path
+ *
+ * Copyright 2011 Vic Lee
+ *
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <freerdp/utils/stream.h>
+
+#include "fastpath.h"
+
+/**
+ * Fast-Path packet format is defined in [MS-RDPBCGR] 2.2.9.1.2, which revises
+ * server output packets from the first byte with the goal of improving
+ * bandwidth.
+ * 
+ * Slow-Path packet always starts with TPKT header, which has the first
+ * byte 0x03, while Fast-Path packet starts with 2 zero bits in the first
+ * two less significant bits of the first byte.
+ */
+
+/**
+ * Read a Fast-Path packet header.\n
+ * @param s stream
+ * @param encryptionFlags
+ * @return length
+ */
+
+uint16 fastpath_read_header(STREAM* s, uint8* encryptionFlags)
+{
+	uint8 header;
+	uint16 length;
+	uint8 t;
+
+	stream_read_uint8(s, header);
+	if (encryptionFlags != NULL)
+		*encryptionFlags = (header & 0xC0) >> 6;
+
+	stream_read_uint8(s, length); /* length1 */
+	/* If most significant bit is not set, length2 is not presented. */
+	if ((length & 0x80))
+	{
+		length &= 0x7F;
+		length <<= 8;
+		stream_read_uint8(s, t);
+		length += t;
+	}
+
+	return length;
+}

libfreerdp-core/fastpath.h

@@ -0,0 +1,39 @@
+/**
+ * FreeRDP: A Remote Desktop Protocol Client
+ * Fast Path
+ *
+ * Copyright 2011 Vic Lee
+ *
+ * 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.
+ */
+
+#ifndef __FASTPATH_H
+#define __FASTPATH_H
+
+#include <freerdp/utils/stream.h>
+
+enum FASTPATH_OUTPUT_ACTION_TYPE
+{
+	FASTPATH_OUTPUT_ACTION_FASTPATH = 0x0,
+	FASTPATH_OUTPUT_ACTION_X224 = 0x3
+};
+
+enum FASTPATH_OUTPUT_ENCRYPTION_FLAGS
+{
+	FASTPATH_OUTPUT_SECURE_CHECKSUM = 0x1,
+	FASTPATH_OUTPUT_ENCRYPTED = 0x2
+};
+
+uint16 fastpath_read_header(STREAM* s, uint8* encryptionFlags);
+
+#endif

libfreerdp-core/rdp.c

@@ -359,6 +359,8 @@ void rdp_process_pdu(rdpRdp* rdp, STREAM* s)
 	uint16 sec_flags;
 	enum DomainMCSPDU MCSPDU;
 
+	/* TODO: Check Fast Path header */
+
 	MCSPDU = DomainMCSPDU_SendDataIndication;
 	mcs_read_domain_mcspdu_header(s, &MCSPDU, &length);
 

libfreerdp-core/transport.c

@@ -30,6 +30,7 @@
 #include <fcntl.h>
 
 #include "tpkt.h"
+#include "fastpath.h"
 #include "credssp.h"
 #include "transport.h"
 
@@ -214,8 +215,8 @@ int transport_check_fds(rdpTransport* transport)
 		stream_peek_uint8(transport->recv_buffer, header);
 		if (header == 0x03) /* TPKT */
 			length = tpkt_read_header(transport->recv_buffer);
-		else /* TODO: Fast Path */
-			length = 0;
+		else /* Fast Path */
+			length = fastpath_read_header(transport->recv_buffer, NULL);
 
 		if (length == 0)
 		{