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.

Depends on neutrinolabs/xorgxrdp#183

README.md

@@ -9,9 +9,15 @@
 ## Overview
 
 **xrdp** provides a graphical login to remote machines using Microsoft
-Remote Desktop Protocol (RDP). xrdp accepts connections from a variety of
-RDP clients: FreeRDP, rdesktop, KRDC, NeutrinoRDP and Microsoft Remote Desktop
-Client (for Windows, Mac OS, iOS and Android).
+Remote Desktop Protocol (RDP). xrdp accepts connections from a variety of RDP clients:
+  - FreeRDP
+  - rdesktop
+  - KRDC
+  - NeutrinoRDP
+  - Windows MSTSC (Microsoft Terminal Services Client)
+  - Microsoft Remote Desktop (which is distinct from MSTSC and the only Microsoft clients that support resizing without reconnection)
+
+Many of these work on some or all of Windows, Mac OS, iOS, and/or Android.
 
 RDP transport is encrypted using TLS by default.
 
@@ -24,7 +30,7 @@ RDP transport is encrypted using TLS by default.
  * Connect to a Linux desktop using RDP from anywhere (requires
    [xorgxrdp](https://github.com/neutrinolabs/xorgxrdp) Xorg module)
  * Reconnect to an existing session
- * Session resizing
+ * Session resizing on connect and while an existing session is active.
  * RDP/VNC proxy (connect to another RDP/VNC server via xrdp)
 
 ### Access to Remote Resources

libxrdp/xrdp_channel.c

@@ -777,6 +777,12 @@ xrdp_channel_drdynvc_start(struct xrdp_channel *self)
     struct mcs_channel_item *dci;
 
 
+    LOG(LOG_LEVEL_INFO, "xrdp_channel_drdynvc_start: drdynvc_channel_id %d", self->drdynvc_channel_id);
+    if (self->drdynvc_channel_id != -1)
+    {
+        LOG(LOG_LEVEL_INFO, "xrdp_channel_drdynvc_start: already started");
+        return 0;
+    }
     dci = NULL;
     count = self->mcs_layer->channel_list->count;
     for (index = 0; index < count; index++)

vnc/vnc.c

@@ -1224,7 +1224,7 @@ send_update_request_for_resize_status(struct vnc *v)
     make_stream(s);
     init_stream(s, 8192);
 
-    switch (v->initial_resize_status)
+    switch (v->resize_status)
     {
         case VRS_WAITING_FOR_FIRST_UPDATE:
             /*
@@ -1364,14 +1364,14 @@ lib_framebuffer_first_update(struct vnc *v)
             {
                 LOG(LOG_LEVEL_DEBUG, "Server layout is the same "
                     "as the client layout");
-                v->initial_resize_status = VRS_DONE;
+                v->resize_status = VRS_DONE;
             }
             else
             {
                 LOG(LOG_LEVEL_DEBUG, "Server layout differs from "
                     "the client layout. Changing server layout");
                 error = send_set_desktop_size(v, &v->client_layout);
-                v->initial_resize_status = VRS_WAITING_FOR_RESIZE_CONFIRM;
+                v->resize_status = VRS_WAITING_FOR_RESIZE_CONFIRM;
             }
         }
         else
@@ -1382,7 +1382,7 @@ lib_framebuffer_first_update(struct vnc *v)
             LOG(LOG_LEVEL_DEBUG, "Resizing client to server %dx%d",
                 v->server_width, v->server_height);
             error = resize_client(v, 0, v->server_width, v->server_height);
-            v->initial_resize_status = VRS_DONE;
+            v->resize_status = VRS_DONE;
         }
 
         g_free(layout.s);
@@ -1437,7 +1437,7 @@ lib_framebuffer_waiting_for_resize_confirm(struct vnc *v)
                     v->server_width, v->server_height);
                 error = resize_client(v, 0, v->server_width, v->server_height);
             }
-            v->initial_resize_status = VRS_DONE;
+            v->resize_status = VRS_DONE;
         }
 
         g_free(layout.s);
@@ -1777,7 +1777,7 @@ lib_mod_process_message(struct vnc *v, struct stream *s)
     {
         if (type == S2C_FRAMEBUFFER_UPDATE)
         {
-            switch (v->initial_resize_status)
+            switch (v->resize_status)
             {
                 case VRS_WAITING_FOR_FIRST_UPDATE:
                     error = lib_framebuffer_first_update(v);
@@ -2237,7 +2237,7 @@ lib_mod_connect(struct vnc *v)
 
     if (error == 0)
     {
-        v->initial_resize_status = VRS_WAITING_FOR_FIRST_UPDATE;
+        v->resize_status = VRS_WAITING_FOR_FIRST_UPDATE;
         error = send_update_request_for_resize_status(v);
     }
 
@@ -2465,6 +2465,34 @@ lib_mod_suppress_output(struct vnc *v, int suppress,
     return error;
 }
 
+/******************************************************************************/
+/* return error */
+int
+lib_mod_server_version_message(struct vnc *v)
+{
+    return 0;
+}
+
+/******************************************************************************/
+/* return error */
+int
+lib_mod_server_monitor_resize(struct vnc *v, int width, int height, int bpp)
+{
+    int error = 0;
+    set_single_screen_layout(&v->client_layout, width, height);
+    v->resize_status = VRS_WAITING_FOR_FIRST_UPDATE;
+    error = send_update_request_for_resize_status(v);
+    return error;
+}
+
+/******************************************************************************/
+/* return error */
+int
+lib_mod_server_monitor_full_invalidate(struct vnc *v, int param1, int param2)
+{
+    return 0;
+}
+
 /******************************************************************************/
 tintptr EXPORT_CC
 mod_init(void)
@@ -2486,6 +2514,9 @@ mod_init(void)
     v->mod_check_wait_objs = lib_mod_check_wait_objs;
     v->mod_frame_ack = lib_mod_frame_ack;
     v->mod_suppress_output = lib_mod_suppress_output;
+    v->mod_server_monitor_resize = lib_mod_server_monitor_resize;
+    v->mod_server_monitor_full_invalidate = lib_mod_server_monitor_full_invalidate;
+    v->mod_server_version_message = lib_mod_server_version_message;
 
     /* Member variables */
     v->enabled_encodings_mask = -1;

vnc/vnc.h

@@ -77,7 +77,12 @@ struct vnc
     int (*mod_frame_ack)(struct vnc *v, int flags, int frame_id);
     int (*mod_suppress_output)(struct vnc *v, int suppress,
                                int left, int top, int right, int bottom);
-    tintptr mod_dumby[100 - 11]; /* align, 100 minus the number of mod
+    int (*mod_server_monitor_resize)(struct vnc *v,
+                               int width, int height, int bpp);
+    int (*mod_server_monitor_full_invalidate)(struct vnc *v,
+                               int width, int height);
+    int (*mod_server_version_message)(struct vnc *v);
+    tintptr mod_dumby[100 - 14]; /* align, 100 minus the number of mod
                                   functions above */
     /* server functions */
     int (*server_begin_update)(struct vnc *v);
@@ -152,5 +157,5 @@ struct vnc
     unsigned int enabled_encodings_mask;
     /* Resizeable support */
     struct vnc_screen_layout client_layout;
-    enum vnc_resize_status initial_resize_status;
+    enum vnc_resize_status resize_status;
 };