C# Signature:
/// <summary>
/// The WTSQuerySessionInformation function retrieves session information for the specified
/// session on the specified terminal server.
/// It can be used to query session information on local and remote terminal servers.
/// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/termserv/termserv/wtsquerysessioninformation.asp
/// </summary>
/// <param name="hServer">Handle to a terminal server. Specify a handle opened by the WTSOpenServer function,
/// or specify <see cref="WTS_CURRENT_SERVER_HANDLE"/> to indicate the terminal server on which your application is running.</param>
/// <param name="sessionId">A Terminal Services session identifier. To indicate the session in which the calling application is running
/// (or the current session) specify <see cref="WTS_CURRENT_SESSION"/>. Only specify <see cref="WTS_CURRENT_SESSION"/> when obtaining session information on the
/// local server. If it is specified when querying session information on a remote server, the returned session
/// information will be inconsistent. Do not use the returned data in this situation.</param>
/// <param name="wtsInfoClass">Specifies the type of information to retrieve. This parameter can be one of the values from the <see cref="WTSInfoClass"/> enumeration type. </param>
/// <param name="ppBuffer">Pointer to a variable that receives a pointer to the requested information. The format and contents of the data depend on the information class specified in the <see cref="WTSInfoClass"/> parameter.
/// To free the returned buffer, call the <see cref="WTSFreeMemory"/> function. </param>
/// <param name="pBytesReturned">Pointer to a variable that receives the size, in bytes, of the data returned in ppBuffer.</param>
/// <returns>If the function succeeds, the return value is a nonzero value.
/// If the function fails, the return value is zero. To get extended error information, call GetLastError.
/// </returns>
[DllImport("Wtsapi32.dll")]
public static extern bool WTSQuerySessionInformation(
System.IntPtr hServer, int sessionId, WTSInfoClass wtsInfoClass, out System.IntPtr ppBuffer, out uint pBytesReturned);
VB .NET Signature:
Private Declare Auto Function WTSQuerySessionInformation Lib "wtsapi32.dll" ( _
ByVal hServer As Int32, _
ByVal SessionId As Int32, _
ByVal InfoClass As WTS_INFO_CLASS, _
ByRef ppBuffer As IntPtr, _
ByRef pCount As Int32) As Int32
User-Defined Types:
Structure:
Notes:
Used in conjunction with WTSGetActiveConsoleSessionId and WTSFreeMemory.
Tips & Tricks:
Please add some!
How to retrieve username by session id:
[DllImport("Wtsapi32.dll")]
private static extern bool WTSQuerySessionInformation(IntPtr hServer, int sessionId, WTS_INFO_CLASS wtsInfoClass, out IntPtr ppBuffer, out int pBytesReturned);
[DllImport("Wtsapi32.dll")]
private static extern void WTSFreeMemory(IntPtr pointer);
public static String GetUsernameBySessionId(int sessionId)
{
IntPtr buffer;
int strLen;
var username = "SYSTEM"; // assume SYSTEM as this will return "\0" below
if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WTS_INFO_CLASS.WTSUserName, out buffer, out strLen) && strLen > 1)
{
username = Marshal.PtrToStringAnsi(buffer); // don't need length as these are null terminated strings
WTSFreeMemory(buffer);
if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WTS_INFO_CLASS.WTSDomainName, out buffer, out strLen) && strLen > 1)
{
username = Marshal.PtrToStringAnsi(buffer)+"\\"+username; // prepend domain name
WTSFreeMemory(buffer);
}
}
return username;
}
Sample Code:
using System;
using System.Runtime.InteropServices;
namespace TerminalServer
{
/// <summary>
/// Static helper methods.
/// </summary>
internal class Utilities
{
/// <summary>
/// The WTSQuerySessionInformation function retrieves session information for the specified
/// session on the specified terminal server.
/// It can be used to query session information on local and remote terminal servers.
/// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/termserv/termserv/wtsquerysessioninformation.asp
/// </summary>
/// <param name="hServer">Handle to a terminal server. Specify a handle opened by the WTSOpenServer function,
/// or specify <see cref="WTS_CURRENT_SERVER_HANDLE"/> to indicate the terminal server on which your application is running.</param>
/// <param name="sessionId">A Terminal Services session identifier. To indicate the session in which the calling application is running
/// (or the current session) specify <see cref="WTS_CURRENT_SESSION"/>. Only specify <see cref="WTS_CURRENT_SESSION"/> when obtaining session information on the
/// local server. If it is specified when querying session information on a remote server, the returned session
/// information will be inconsistent. Do not use the returned data in this situation.</param>
/// <param name="wtsInfoClass">Specifies the type of information to retrieve. This parameter can be one of the values from the <see cref="WTSInfoClass"/> enumeration type. </param>
/// <param name="ppBuffer">Pointer to a variable that receives a pointer to the requested information. The format and contents of the data depend on the information class specified in the <see cref="WTSInfoClass"/> parameter.
/// To free the returned buffer, call the <see cref="WTSFreeMemory"/> function. </param>
/// <param name="pBytesReturned">Pointer to a variable that receives the size, in bytes, of the data returned in ppBuffer.</param>
/// <returns>If the function succeeds, the return value is a nonzero value.
/// If the function fails, the return value is zero. To get extended error information, call GetLastError.
/// </returns>
[DllImport("Wtsapi32.dll")]
public static extern bool WTSQuerySessionInformation(
System.IntPtr hServer, int sessionId, WTSInfoClass wtsInfoClass, out System.IntPtr ppBuffer, out uint pBytesReturned);
// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/termserv/termserv/wtsgetactiveconsolesessionid.asp
/// <summary>
/// The WTSGetActiveConsoleSessionId function retrieves the
/// Terminal Services session currently attached to the physical console.
/// The physical console is the monitor, keyboard, and mouse.
/// </summary>
/// <returns>An <see cref="int"/> equal to 0 indicates that the current session is attached to the physical console.</returns>
/// <remarks>It is not necessary that Terminal Services be running for this function to succeed.</remarks>
[DllImport("Kernel32.dll")]
public static extern int WTSGetActiveConsoleSessionId();
/// <summary>
/// The WTSFreeMemory function frees memory allocated by a Terminal Services function.
/// </summary>
/// <param name="memory">Pointer to the memory to free.</param>
[DllImport("wtsapi32.dll", ExactSpelling=true, SetLastError=false)]
public static extern void WTSFreeMemory( IntPtr memory );
public const int WTS_CURRENT_SESSION = -1;
/// <summary>
/// Gets a <see cref="bool"/> indicating if the current ehmsas.exe is being run locally or in a Remote session.
/// </summary>
/// <returns>Returns true if the process is being executed locally or from a Terminal Server session.</returns>
internal static bool GetIsRunningLocally()
{
System.IntPtr buffer = IntPtr.Zero;
uint bytesReturned;
int sessionID;
try
{
bool sessionInfo = WTSQuerySessionInformation( System.IntPtr.Zero, WTS_CURRENT_SESSION, WTSInfoClass.WTSSessionId, out buffer, out bytesReturned );
sessionID = Marshal.ReadInt32( buffer );
}
catch
{
return true;
}
finally
{
WTSFreeMemory( buffer );
buffer = IntPtr.Zero;
}
int currentSessionId = WTSGetActiveConsoleSessionId();
if (currentSessionId == sessionID)
{
return true;
}
else
{
return false;
}
}
}
}
Alternative Managed API:
TODO
