How to Use WNetGetUser() in Windows for Workgroups from VB 3.0

MORE INFORMATION

Until the release of the Windows for Workgroups Software Development Kit (SDK), the WNetGetUser() function was used internally by Windows. It is documented in the Windows version 3.1 "Device Driver Adaptation Guide" for network device driver developers.

Now the Windows for Workgroups SDK allows you to call WNetGetUser() from an application. However, when using this function on a system with a multinet driver, you must activate the supporting network by first using MNetSetNextTarget(). If the target network has not been set, the function returns WN_SUCCESS but the returned string for the user name is empty. This is documented in the description of MNetSetNextTarget() in the Windows for Workgroups SDK.

It is not sufficient to just call MNetSetNextTarget() before WNetGetUser(). The current target network may not support WNetGetUser(). To set the target network to use WNetGetUser() correctly, you must number the networks and call WNetGetUser() for each network. If WNetGetUser() does not return WN_SUCCESS, then increment the network number for the next target network and iterate the loop. If the loop iterates through all of the networks but WNetGetUser() never returns WN_SUCCESS, then none of the target networks support WNetGetUser(). The following sample code demonstrates how to do this.

Step-by-Step Example

1. Start a new project in Visual Basic. Form1 is created by default.
2. Add the following code to the General Declarations section of Form1:

      ' Enter each of the following Declare statements on one, single line:
      Declare Function WNetGetUser Lib "wfwnet.drv" (ByVal szUser As String,
         nBufferSize As Integer) As Integer
      Declare Function MNetNetworkEnum Lib "wfwnet.drv"
        (lphNetwork As Integer) As Integer
      Declare Function MNetSetNextTarget Lib "wfwnet.drv"
         (ByVal hNetwork As Integer) As Integer
   
      ' The following function determines the logged-in user in Windows for
      ' Workgroups:
      Function MultiNetGetUser (UserName$) As Integer
   
         Dim hNetDrv As Integer
         Dim wRetEnum As Integer, ret As Integer
         Dim wRetGetUser As Integer
         Dim cb As Integer
         Dim Found As Integer
   
         Found = False
         ' Grab the 1st network:
         hNetDrv = 0
         wRetEnum = MNetNetworkEnum(hNetDrv)
   
         ' Loop while there are installed networks:
         While (wRetEnum = 0) And Not Found
            user$ = Space$(255)
            cb = Len(user$)
   
            ' Make sure correct network is accessed in next WNetGetUser call:
            ret = MNetSetNextTarget(hNetDrv)
   
            ' Get the user:
            wRetGetUser = WNetGetUser(user$, cb)
   
            ' Check for success:
            If wRetGetUser = 0 Then
               ' Just grab the relevant characters:
               UserName$ = Left$(user$, cb - 1)
               MsgBox UserName$, , "WNetGetUser"
               Found = True
            End If
   
            ' Get the next network:
            wRetEnum = MNetNetworkEnum(hNetDrv)
         Wend
         If Not Found Then
            MsgBox "WNetGetUser not supported on any of the Multinet subnets"
         End If
   
         MultiNetGetUser = Found
   
      End Function
   
   						

3. Put a command button (Command1) on the form.
4. Add the following code to the Command1 Click event:

      Sub Command1_Click()
         r = MultiNetGetUser(UserName$)
      End Sub
   
   						

5. Save the project.
6. Run the program. A message box should pop up displaying the user name.

NOTE: To determine whether a system supports multinet operations, MNetGetCaps() can be used with WNNC_NET_TYPE. The return value has the WNNC_NET_MultiNet (0x8000) set if the system supports multinet operations.