Milestone 5: deliver embedded RDP sessions and lifecycle hardening

third_party/FreeRDP/channels/remdesk/common/remdesk_common.c

@@ -0,0 +1,105 @@
+/**
+ * FreeRDP: A Remote Desktop Protocol Implementation
+ * Remote Assistance Virtual Channel - common components
+ *
+ * Copyright 2024 Armin Novak <armin.novak@thincast.com>
+ * Copyright 2024 Thincast Technologies GmbH
+ *
+ * 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 "remdesk_common.h"
+
+#include <freerdp/channels/log.h>
+#define TAG CHANNELS_TAG("remdesk.common")
+
+UINT remdesk_write_channel_header(wStream* s, const REMDESK_CHANNEL_HEADER* header)
+{
+	WCHAR ChannelNameW[32] = WINPR_C_ARRAY_INIT;
+
+	WINPR_ASSERT(s);
+	WINPR_ASSERT(header);
+
+	for (size_t index = 0; index < 32; index++)
+	{
+		ChannelNameW[index] = (WCHAR)header->ChannelName[index];
+	}
+
+	const size_t ChannelNameLen =
+	    (strnlen(header->ChannelName, sizeof(header->ChannelName)) + 1) * sizeof(WCHAR);
+	WINPR_ASSERT(ChannelNameLen <= ARRAYSIZE(header->ChannelName));
+
+	Stream_Write_UINT32(s, (UINT32)ChannelNameLen); /* ChannelNameLen (4 bytes) */
+	Stream_Write_UINT32(s, header->DataLength);     /* DataLen (4 bytes) */
+	Stream_Write(s, ChannelNameW, ChannelNameLen);  /* ChannelName (variable) */
+	return CHANNEL_RC_OK;
+}
+
+UINT remdesk_write_ctl_header(wStream* s, const REMDESK_CTL_HEADER* ctlHeader)
+{
+	WINPR_ASSERT(ctlHeader);
+	const UINT error = remdesk_write_channel_header(s, &ctlHeader->ch);
+
+	if (error != 0)
+	{
+		WLog_ERR(TAG, "remdesk_write_channel_header failed with error %" PRIu32 "!", error);
+		return error;
+	}
+
+	Stream_Write_UINT32(s, ctlHeader->msgType); /* msgType (4 bytes) */
+	return CHANNEL_RC_OK;
+}
+
+UINT remdesk_read_channel_header(wStream* s, REMDESK_CHANNEL_HEADER* header)
+{
+	UINT32 ChannelNameLen = 0;
+
+	if (!Stream_CheckAndLogRequiredLength(TAG, s, 8))
+		return CHANNEL_RC_NO_MEMORY;
+
+	Stream_Read_UINT32(s, ChannelNameLen);     /* ChannelNameLen (4 bytes) */
+	Stream_Read_UINT32(s, header->DataLength); /* DataLen (4 bytes) */
+
+	if (ChannelNameLen > 64)
+	{
+		WLog_ERR(TAG, "ChannelNameLen > 64!");
+		return ERROR_INVALID_DATA;
+	}
+
+	if ((ChannelNameLen % 2) != 0)
+	{
+		WLog_ERR(TAG, "(ChannelNameLen %% 2) != 0!");
+		return ERROR_INVALID_DATA;
+	}
+
+	if (Stream_Read_UTF16_String_As_UTF8_Buffer(s, ChannelNameLen / sizeof(WCHAR),
+	                                            header->ChannelName,
+	                                            ARRAYSIZE(header->ChannelName)) < 0)
+		return ERROR_INVALID_DATA;
+
+	return CHANNEL_RC_OK;
+}
+
+UINT remdesk_prepare_ctl_header(REMDESK_CTL_HEADER* ctlHeader, UINT32 msgType, size_t msgSize)
+{
+	WINPR_ASSERT(ctlHeader);
+
+	if (msgSize > UINT32_MAX - 4)
+		return ERROR_INVALID_PARAMETER;
+
+	ctlHeader->msgType = msgType;
+	(void)sprintf_s(ctlHeader->ch.ChannelName, ARRAYSIZE(ctlHeader->ch.ChannelName),
+	                REMDESK_CHANNEL_CTL_NAME);
+	ctlHeader->ch.DataLength = (UINT32)(4UL + msgSize);
+	return CHANNEL_RC_OK;
+}