Visual Basic Network Services
Obtaining Workstation Configuration and Current User
     
Posted:   Monday June 25, 2001
Updated:   Monday December 26, 2011
     
Applies to:   VB4-32, VB5, VB6
Developed with:   VB6, Windows 2000
OS restrictions:   Windows NT3.1, Windows NT4, Windows 2000, Windows XP
Author:   VBnet - Randy Birch
     

Related:  

NetWkstaGetInfo: Workstation Configuration Information 
NetWkstaUserEnum: Workstation Logon Information
 
NetWkstaGetInfo: Workstation Configuration and Current User
 
NetWkstaGetInfo: Workstation Configuration and Logon Information
 

     
 Prerequisites
For this demo, one of the operating systems listed under OS Restrictions above.

This demo combines NetWkstaGetInfo and NetWkstaUserEnum to retrieve the workstation information, passing the server to NetWkstaUserEnum in order to obtain just the name of the user currently logged on to the workstation.

The WKSTA_INFO_102 structure used by NetWkstaGetInfo returns information about a workstation environment, including platform-specific information, the names of the domain (or workgroup) and the local computer, number of users logged on to the local computer, as well as information concerning the operating system on the machine.

The WKSTA_USER_INFO_0 structure used by NetWkstaUserEnum contains a single member returning only the name of the user currently logged on to the workstation. Should more information be required, such as the domain, authenticating computer, or other domains browsed by the workstation, pass a WKSTA_USER_INFO_1 structure instead as shown in NetWkstaGetInfo: Workstation Configuration and Logon Information

The security requirements are the same as those outlined in NetWkstaUserEnum: Workstation Logon Information.

 BAS Module Code
None.

 Form Code
To a form add a command button (Command1), list box (List1), and two labels (Label1, Label2). A third set of labels in a control array can be used for the list item captions. Add the following to the form:

Option Explicit
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright 1996-2011 VBnet/Randy Birch, All Rights Reserved.
' Some pages may also contain other copyrights by the author.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Distribution: You can freely use this code in your own
'               applications, but you may not reproduce 
'               or publish this code on any web site,
'               online service, or distribute as source 
'               on any media without express permission.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Private Const NERR_SUCCESS As Long = 0&
Private Const MAX_PREFERRED_LENGTH As Long = -1
Private Const ERROR_MORE_DATA As Long = 234&
Private Const LB_SETTABSTOPS As Long = &H192

'for use on Win NT/2000 only
Private Type WKSTA_INFO_102
  wki102_platform_id As Long
  wki102_computername As Long
  wki102_langroup As Long
  wki102_ver_major As Long
  wki102_ver_minor As Long
  wki102_lanroot As Long
  wki102_logged_on_users As Long
End Type

Private Type WKSTA_USER_INFO_0
  wkui0_username  As Long
End Type

Private Declare Function NetWkstaGetInfo Lib "netapi32" _
  (ByVal servername As Long, _
   ByVal level As Long, _
   bufptr As Long) As Long
   
Private Declare Function NetWkstaUserEnum Lib "netapi32" _
  (ByVal servername As Long, _
   ByVal level As Long, _
   bufptr As Long, _
   ByVal prefmaxlen As Long, _
   entriesread As Long, _
   totalentries As Long, _
   resume_handle As Long) As Long
   
Private Declare Function NetApiBufferFree Lib "netapi32" _
   (ByVal Buffer As Long) As Long

'common
Private Declare Sub CopyMemory Lib "kernel32" _
   Alias "RtlMoveMemory" _
  (pTo As Any, _
   uFrom As Any, _
   ByVal lSize As Long)
   
Private Declare Function lstrlenW Lib "kernel32" _
  (ByVal lpString As Long) As Long

Private Declare Function SendMessage Lib "user32" _
   Alias "SendMessageA" _
  (ByVal hwnd As Long, _
   ByVal wMsg As Long, _
   ByVal wParam As Long, _
   lParam As Any) As Long


Private Sub Form_Load()

   ReDim TabArray(0 To 6) As Long
   
   TabArray(0) = 78
   TabArray(1) = 129
   TabArray(2) = 159
   TabArray(3) = 198
   TabArray(4) = 227
   TabArray(5) = 253
   TabArray(6) = 302

  'Clear existing tabs and set list tabstops
   Call SendMessage(List1.hwnd, LB_SETTABSTOPS, 0&, ByVal 0&)
   Call SendMessage(List1.hwnd, LB_SETTABSTOPS, 7&, TabArray(0))
   List1.Refresh

   Command1.Caption = "NetWkstaGetInfo"
   
   Label1.Caption = "call success (0) or error :"
   Label2.Caption = ""
      
End Sub


Private Sub Command1_Click()

   Dim bufptr          As Long
   Dim dwServer        As Long
   Dim success         As Long
   Dim nStructSize     As Long
   Dim bServer         As String
   Dim ws102           As WKSTA_INFO_102
   
   bServer = "\\" & Environ$("COMPUTERNAME") & vbNullString

   List1.Clear
   Label2.Caption = success
   
   dwServer = StrPtr(bServer)
   
   success = NetWkstaGetInfo(dwServer, 102, bufptr)

   If success = NERR_SUCCESS And _
      success <> ERROR_MORE_DATA Then
      
      nStructSize = LenB(ws102)
      
        'cast data into a WKSTA_INFO_102 type
        'and add the data to a list, calling
        'the GetWorkstationUserName function
        'to retrieve the logon username for
        'the dwServer passed
         CopyMemory ws102, ByVal bufptr, nStructSize

         List1.AddItem GetPointerToByteStringW(ws102.wki102_computername) & vbTab & _
                       GetPointerToByteStringW(ws102.wki102_langroup) & vbTab & _
                       ws102.wki102_logged_on_users & vbTab & _
                       ws102.wki102_platform_id & vbTab & _
                       ws102.wki102_ver_major & vbTab & _
                       ws102.wki102_ver_minor & vbTab & _
                       GetWorkstationUserName(dwServer)
                       
   End If
   
   Call NetApiBufferFree(bufptr)
      
End Sub


Private Function GetPointerToByteStringW(ByVal dwData As Long) As String
  
   Dim tmp() As Byte
   Dim tmplen As Long
   
   If dwData <> 0 Then
   
      tmplen = lstrlenW(dwData) * 2
      
      If tmplen <> 0 Then
      
         ReDim tmp(0 To (tmplen - 1)) As Byte
         CopyMemory tmp(0), ByVal dwData, tmplen
         GetPointerToByteStringW = tmp
         
     End If
     
   End If
    
End Function


Private Function GetWorkstationUserName(ByVal dwWorkstation As Long) As String

   Dim bufptr          As Long
   Dim dwEntriesread   As Long
   Dim dwTotalentries  As Long
   Dim dwResumehandle  As Long
   Dim success         As Long
   Dim nStructSize     As Long
   Dim wui0            As WKSTA_USER_INFO_0
   
   success = NetWkstaUserEnum(dwWorkstation, _
                              0, _
                              bufptr, _
                              MAX_PREFERRED_LENGTH, _
                              dwEntriesread, _
                              dwTotalentries, _
                              dwResumehandle)

   If success = NERR_SUCCESS And _
      success <> ERROR_MORE_DATA Then
      
      nStructSize = LenB(wui0)
      
      If dwEntriesread > 0 Then

        'cast data into WKSTA_USER_INFO_0 since
        'we only need the user name. Although this
        'API enumerates and returns information
        'about all users currently logged on to
        'the workstation, including interactive,
        'service and batch logons, chances are
        'that the first user enumerated was the
        'user who logged on the session so we
        'exit after the first user info is returned.
        '
        'If this presumption is incorrect, please 
        'let me know via the VBnet Comments link.
         CopyMemory wui0, ByVal bufptr, nStructSize
         
         GetWorkstationUserName = GetPointerToByteStringW(wui0.wkui0_username)
         
        'clean up 
         Call NetApiBufferFree(bufptr)
         Exit Function
         
      End If

   End If
   

  'if the dwWorkstation  passed was a Win9x
  'machine, dwEntriesread was 0, so return
  'a default string.
   
   GetWorkstationUserName = "n\a on Win9x"
   Call NetApiBufferFree(bufptr)
   
End Function
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