Detecting the Remote Desktop Services environment

To optimize performance, it is good practice for applications to detect whether they are running in a Remote Desktop Services client session. For example, when an application is running on a remote session, it should eliminate unnecessary graphic effects, as described in Graphic Effects. If the user is running the application in a local environment, it is not as critical for the application to optimize its behavior.

The following example shows a function that returns TRUE if the application is running in a remote session and FALSE if the application is running on the console.


#include <windows.h>
#pragma comment(lib, "user32.lib")

BOOL IsRemoteSession(void)
{
   return GetSystemMetrics( SM_REMOTESESSION );
}


For more information, see Run-time Linking to Wtsapi32.dll.

You should not use GetSystemMetrics(SM_REMOTESESSION) to determine if your application is running in a remote session in Windows 8 and later or Windows Server 2012 and later if the remote session may also be using the RemoteFX vGPU improvements to the Microsoft Remote Display Protocol (RDP). In this case, GetSystemMetrics(SM_REMOTESESSION) will identify the remote session as a local session.

Your application can check the following registry key to determine whether the session is a remote session that uses RemoteFX vGPU. If a local session exists, this registry key provides the ID of the local session.

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\GlassSessionId

If the ID of the current session in which the application is running is the same as in the registry key, the application is running in a local session. Sessions identified as remote session in this way include remote sessions that use RemoteFX vGPU. The following sample code demonstrates this.


#define TERMINAL_SERVER_KEY _T("SYSTEM\\CurrentControlSet\\Control\\Terminal Server\\")
#define GLASS_SESSION_ID    _T("GlassSessionId")

BOOL
IsCurrentSessionRemoteable()
{
    BOOL fIsRemoteable = FALSE;
                                       
    if (GetSystemMetrics(SM_REMOTESESSION)) 
    {
        fIsRemoteable = TRUE;
    }
    else
    {
        HKEY hRegKey = NULL;
        LONG lResult;

        lResult = RegOpenKeyEx(
            HKEY_LOCAL_MACHINE,
            TERMINAL_SERVER_KEY,
            0, // ulOptions
            KEY_READ,
            &hRegKey
            );

        if (lResult == ERROR_SUCCESS)
        {
            DWORD dwGlassSessionId;
            DWORD cbGlassSessionId = sizeof(dwGlassSessionId);
            DWORD dwType;

            lResult = RegQueryValueEx(
                hRegKey,
                GLASS_SESSION_ID,
                NULL, // lpReserved
                &dwType,
                (BYTE*) &dwGlassSessionId,
                &cbGlassSessionId
                );

            if (lResult == ERROR_SUCCESS)
            {
                DWORD dwCurrentSessionId;

                if (ProcessIdToSessionId(GetCurrentProcessId(), &dwCurrentSessionId))
                {
                    fIsRemoteable = (dwCurrentSessionId != dwGlassSessionId);
                }
            }
        }

        if (hRegKey)
        {
            RegCloseKey(hRegKey);
        }
    }

    return fIsRemoteable;
}


 

 

Show:
© 2014 Microsoft