Resolution switching without reconnecting.

- Based on https://github.com/jsorg71/xrdp/tree/dynamic_monitor
- Tested with xorgxrdp
- Tested with vnc
- Only works with single monitor.
- Update documentation to clarify the difference between MSTSC and
Microsoft Remote Desktop.
- Does not include compatibility with /gfx at this time, which is still
in testing.
- Updates to include ms-rdpedisp.h header for the 2.2.2 specification of
the protocol.
- Adds new dynamic_monitor_layout struct that shares the number of
monitors with xrdp_client_info.h
- Does not allow for BPP changes because the RDP protocol doesn't
support it.
- Option to disable feature as NeutrinoRDP doesn't support it (It was
based on FreeRDP 1.0.1 which didn't yet have this feature.)
- Add CLIENT_MONITOR_DATA_MAXIMUM_MONITORS constant and reference
spec definition.

Depends on https://github.com/neutrinolabs/xorgxrdp/pull/183

common/Makefile.am

@@ -14,6 +14,7 @@ include_HEADERS = \
   ms-rdpegdi.h \
   ms-rdpele.h \
   ms-rdperp.h \
+  ms-rdpedisp.h \
   ms-smb2.h \
   xrdp_client_info.h \
   xrdp_constants.h \

common/ms-rdpbcgr.h

@@ -78,7 +78,12 @@
 /* This isn't explicitly named in MS-RDPBCGR */
 #define CHANNEL_NAME_LEN                7
 
-/* Oprions field */
+/* 2.2.1.3.6 Client Monitor Data - */
+/* monitorCount (4 bytes): A 32-bit, unsigned integer. The number of display */
+/* monitor definitions in the monitorDefArray field (the maximum allowed is 16). */
+#define CLIENT_MONITOR_DATA_MAXIMUM_MONITORS 16
+
+/* Options field */
 /* NOTE: XR_ prefixed to avoid conflict with FreeRDP */
 #define XR_CHANNEL_OPTION_INITIALIZED   0x80000000
 #define XR_CHANNEL_OPTION_ENCRYPT_RDP   0x40000000

common/ms-rdpedisp.h

@@ -0,0 +1,29 @@
+/**
+ * xrdp: A Remote Desktop Protocol server.
+ *
+ * MS-RDPEDISP : Definitions from [MS-RDPEDISP]
+ *
+ * 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.
+ *
+ * References to MS-RDPEDISP are currently correct for v20201030 of that
+ * document
+ */
+
+#if !defined(MS_RDPEDISP_H)
+#define MS_RDPEDISP_H
+
+/* Display Control Messages: Display Virtual Channel Extension (2.2.2) */
+#define DISPLAYCONTROL_PDU_TYPE_MONITOR_LAYOUT 0x00000002
+#define DISPLAYCONTROL_PDU_TYPE_CAPS           0x00000005
+
+#endif /* MS_RDPEDISP_H */

common/xrdp_client_info.h

@@ -19,6 +19,7 @@
  */
 
 #include "xrdp_constants.h"
+#include "ms-rdpbcgr.h"
 
 #if !defined(XRDP_CLIENT_INFO_H)
 #define XRDP_CLIENT_INFO_H
@@ -120,8 +121,8 @@ struct xrdp_client_info
     int security_layer; /* 0 = rdp, 1 = tls , 2 = hybrid */
     int multimon; /* 0 = deny , 1 = allow */
     int monitorCount; /* number of monitors detected (max = 16) */
-    struct monitor_info minfo[16]; /* client monitor data */
-    struct monitor_info minfo_wm[16]; /* client monitor data, non-negative values */
+    struct monitor_info minfo[CLIENT_MONITOR_DATA_MAXIMUM_MONITORS]; /* client monitor data */
+    struct monitor_info minfo_wm[CLIENT_MONITOR_DATA_MAXIMUM_MONITORS]; /* client monitor data, non-negative values */
 
     int keyboard_type;
     int keyboard_subtype;