C# Signature:
[DllImport("wtsapi32.dll", SetLastError=true)]
static extern int WTSEnumerateSessions(
System.IntPtr hServer,
int Reserved,
int Version,
ref System.IntPtr ppSessionInfo,
ref int pCount);
[DllImport("wtsapi32.dll", SetLastError=true)]
static extern void WTSEnumerateSessions(
System.IntPtr hServer,
ref System.IntPtr ppSessionInfo,
ref int pCount)
{
WTSEnumerateSessions(hServer,0,1,ppSessionInfo,pCount);
}
C# Example
// Note the VB example will give you the first entry of the array n times where n is the size of the array
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
namespace TerminalServices
{
class TSManager
{
[DllImport("wtsapi32.dll", SetLastError=true)]
static extern IntPtr WTSOpenServer([MarshalAs(UnmanagedType.LPStr)] String pServerName);
[DllImport("wtsapi32.dll")]
static extern void WTSCloseServer(IntPtr hServer);
[DllImport("wtsapi32.dll", SetLastError=true)]
static extern Int32 WTSEnumerateSessions(
IntPtr hServer,
[MarshalAs(UnmanagedType.U4)] Int32 Reserved,
[MarshalAs(UnmanagedType.U4)] Int32 Version,
ref IntPtr ppSessionInfo,
[MarshalAs(UnmanagedType.U4)] ref Int32 pCount);
[DllImport("wtsapi32.dll")]
static extern void WTSFreeMemory(IntPtr pMemory);
[StructLayout(LayoutKind.Sequential)]
private struct WTS_SESSION_INFO
{
public Int32 SessionID;
[MarshalAs(UnmanagedType.LPStr)]
public String pWinStationName;
public WTS_CONNECTSTATE_CLASS State;
}
public enum WTS_CONNECTSTATE_CLASS
{
WTSActive,
WTSConnected,
WTSConnectQuery,
WTSShadow,
WTSDisconnected,
WTSIdle,
WTSListen,
WTSReset,
WTSDown,
WTSInit
}
public static IntPtr OpenServer(String Name)
{
IntPtr server = WTSOpenServer(Name);
return server;
}
public static void CloseServer(IntPtr ServerHandle)
{
WTSCloseServer(ServerHandle);
}
public static List<String> ListSessions(String ServerName)
{
IntPtr server = IntPtr.Zero;
List<String> ret = new List<string>();
server = OpenServer(ServerName);
try
{
IntPtr ppSessionInfo = IntPtr.Zero;
Int32 count = 0;
Int32 retval = WTSEnumerateSessions(server, 0, 1, ref ppSessionInfo, ref count);
Int32 dataSize = Marshal.SizeOf(typeof(WTS_SESSION_INFO));
Int64 current = (int)ppSessionInfo;
if (retval != 0)
{
for (int i = 0; i < count; i++)
{
WTS_SESSION_INFO si = (WTS_SESSION_INFO)Marshal.PtrToStructure((System.IntPtr)current, typeof(WTS_SESSION_INFO));
current += dataSize;
ret.Add(si.SessionID + " " + si.State + " " + si.pWinStationName);
}
WTSFreeMemory(ppSessionInfo);
}
}
finally
{
CloseServer(server);
}
return ret;
}
}
}
VB Signature:
<DllImport("wtsapi32.dll", _
bestfitmapping:=True, _
CallingConvention:=CallingConvention.StdCall, _
CharSet:=CharSet.Auto, _
EntryPoint:="WTSEnumerateSessions", _
setlasterror:=True, _
ThrowOnUnmappableChar:=True)> _
Private Shared Function WTSEnumerateSessions( _
ByVal hServer As IntPtr, _
<MarshalAs(UnmanagedType.U4)> _
ByVal Reserved As Int32, _
<MarshalAs(UnmanagedType.U4)> _
ByVal Version As Int32, _
ByRef ppSessionInfo As IntPtr, _
<MarshalAs(UnmanagedType.U4)> _
ByRef pCount As Int32) As Int32
End Function
User-Defined Types:
Private Enum WTS_CONNECTSTATE_CLASS
WTSActive
WTSConnected
WTSConnectQuery
WTSShadow
WTSDisconnected
WTSIdle
WTSListen
WTSReset
WTSDown
WTSInit
End Enum
<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _
Private Structure WTS_SESSION_INFO
Dim SessionID As Int32 'DWORD integer
Dim pWinStationName As String ' integer LPTSTR - Pointer to a null-terminated string containing the name of the WinStation for this session
Dim State As WTS_CONNECTSTATE_CLASS
End Structure
Notes:
None.
Tips & Tricks:
Please add some!
Sample Code:
Option Explicit On
Option Strict On
Imports System.Runtime.InteropServices
Public Class ManagedWTSAPI
Private Enum WTS_CONNECTSTATE_CLASS
WTSActive
WTSConnected
WTSConnectQuery
WTSShadow
WTSDisconnected
WTSIdle
WTSListen
WTSReset
WTSDown
WTSInit
End Enum
<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _
Private Structure WTS_SESSION_INFO
Dim SessionID As Int32 'DWORD integer
Dim pWinStationName As String ' integer LPTSTR - Pointer to a null-terminated string containing the name of the WinStation for this session
Dim State As WTS_CONNECTSTATE_CLASS
End Structure
Friend Structure strSessionsInfo
Dim SessionID As Integer
Dim StationName As String
Dim ConnectionState As String
End Structure
<DllImport("wtsapi32.dll", _
bestfitmapping:=True, _
CallingConvention:=CallingConvention.StdCall, _
CharSet:=CharSet.Auto, _
EntryPoint:="WTSEnumerateSessions", _
setlasterror:=True, _
ThrowOnUnmappableChar:=True)> _
Private Shared Function WTSEnumerateSessions( _
ByVal hServer As IntPtr, _
<MarshalAs(UnmanagedType.U4)> _
ByVal Reserved As Int32, _
<MarshalAs(UnmanagedType.U4)> _
ByVal Vesrion As Int32, _
ByRef ppSessionInfo As IntPtr, _
<MarshalAs(UnmanagedType.U4)> _
ByRef pCount As Int32) As Int32
End Function
<DllImport("wtsapi32.dll")> _
Private Shared Sub WTSFreeMemory(ByVal pMemory As IntPtr)
End Sub
<DllImport("wtsapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Private Shared Function WTSOpenServer(ByVal pServerName As String) As IntPtr
End Function
<DllImport("wtsapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Private Shared Sub WTSCloseServer(ByVal hServer As IntPtr)
End Sub
Friend Function GetSessions(ByVal ServerName As String) As strSessionsInfo()
Dim ptrOpenedServer As IntPtr
Dim RetVal As strSessionsInfo()
Try
ptrOpenedServer = WTSOpenServer(ServerName)
Dim FRetVal As Int32
Dim ppSessionInfo As IntPtr = IntPtr.Zero
Dim Count As Int32 = 0
Try
FRetVal = WTSEnumerateSessions(ptrOpenedServer, 0, 1, ppSessionInfo, Count)
If FRetVal <> 0 Then
Dim sessionInfo() As WTS_SESSION_INFO = New WTS_SESSION_INFO(Count) {}
Dim i As Integer
Dim DataSize = Marshal.SizeOf(New WTS_SESSION_INFO)
Dim current As Int64
current = ppSessionInfo.ToInt64
For i = 0 To Count - 1 ' Step i + 1
sessionInfo(i) = CType(Marshal.PtrToStructure(New IntPtr(current), GetType(WTS_SESSION_INFO)), WTS_SESSION_INFO)
current = current + DataSize
Next
WTSFreeMemory(ppSessionInfo)
Dim tmpArr(sessionInfo.GetUpperBound(0)) As strSessionsInfo
For i = 0 To tmpArr.GetUpperBound(0)
tmpArr(i).SessionID = sessionInfo(i).SessionID
tmpArr(i).StationName = sessionInfo(i).pWinStationName
tmpArr(i).ConnectionState = GetConnectionState(sessionInfo(i).State)
Next
ReDim sessionInfo(-1)
RetVal = tmpArr
Else
Throw New ApplicationException("No data retruned")
End If
Catch ex As Exception
Throw New Exception(ex.Message & vbCrLf & System.Runtime.InteropServices.Marshal.GetLastWin32Error)
End Try
Catch ex As Exception
Throw New Exception(ex.Message)
Exit Function
Finally
WTSCloseServer(ptrOpenedServer)
End Try
Return RetVal
End Function
Private Function GetConnectionState(ByVal State As WTS_CONNECTSTATE_CLASS) As String
Dim RetVal As String
Select Case State
Case WTS_CONNECTSTATE_CLASS.WTSActive
RetVal = "Active"
Case WTS_CONNECTSTATE_CLASS.WTSConnected
RetVal = "Connected"
Case WTS_CONNECTSTATE_CLASS.WTSConnectQuery
RetVal = "Query"
Case WTS_CONNECTSTATE_CLASS.WTSDisconnected
RetVal = "Disconnected"
Case WTS_CONNECTSTATE_CLASS.WTSDown
RetVal = "Down"
Case WTS_CONNECTSTATE_CLASS.WTSIdle
RetVal = "Idle"
Case WTS_CONNECTSTATE_CLASS.WTSInit
RetVal = "Initializing."
Case WTS_CONNECTSTATE_CLASS.WTSListen
RetVal = "Listen"
Case WTS_CONNECTSTATE_CLASS.WTSReset
RetVal = "reset"
Case WTS_CONNECTSTATE_CLASS.WTSShadow
RetVal = "Shadowing"
Case Else
RetVal = "Unknown connect state"
End Select
Return RetVal
End Function
End Class
Alternative Managed API:
Do you know one? Please contribute it!
