How To Use the WNetUseConnection API to Map a Drive in Visual Basic (256847)

MORE INFORMATION

At times, it is necessary to map a drive letter to a network share. There are several API functions that can be used to accomplish this, such as WNetAddConnection, WNetAddConnection2, WNetAddConnection3, and WNetUseConnection. The primary difference is that with the WNetUseConnection function, you do not need to specify the drive letter to be used, while it is required with the other API functions.

Steps to Create Sample

1. Create a new Standard EXE project in Visual Basic. Form1 is created by default.
2. Add three TextBox controls to Form1 and name them txtUNC, txtUser, and txtPWD.
3. Set the PasswordChar property of txtPWD to an asterisk (*).
4. Add two CommandButtons to Form1 and set their Captions to CONNECT and DISCONNECT.
5. Paste the following code into the code window of Form1:

   Option Explicit
   
   ' CONSTANTS
   Private Const NO_ERROR = 0
   Private Const CONNECT_LOCALDRIVE = 256
   Private Const CONNECT_REDIRECT = 128
   Private Const RESOURCE_GLOBALNET = &H2
   Private Const RESOURCETYPE_DISK = &H1
   Private Const RESOURCEDISPLAYTYPE_SHARE = &H3
   Private Const RESOURCEUSAGE_CONNECTABLE = &H1
   Private Const CONNECT_UPDATE_PROFILE = 1
   
   ' LOCAL VARIABLES
   Private MappedDrive As String
   
   ' CUSTOM TYPES
   Private Type NETRESOURCE
       dwScope As Long
       dwType As Long
       dwDisplayType As Long
       dwUsage As Long
       lpLocalName As String
       lpRemoteName As String
       lpComment As String
       lpProvider As String
   End Type
   
   ' API DECLARATIONS
   Private Declare Function WNetUseConnection Lib "mpr.dll" _
      Alias "WNetUseConnectionA" ( _
      ByVal hwndOwner As Long, _
      ByRef lpNetResource As NETRESOURCE, _
      ByVal lpUsername As String, _
      ByVal lpPassword As String, _
      ByVal dwFlags As Long, _
      ByVal lpAccessName As Any, _
      ByRef lpBufferSize As Long, _
      ByRef lpResult As Long) _
      As Long
   
   Private Declare Function WNetCancelConnection2 Lib "mpr.dll" _
      Alias "WNetCancelConnection2A" ( _
      ByVal lpName As String, _
      ByVal dwFlags As Long, _
      ByVal fForce As Long) _
      As Long
   
   Private Sub Command1_Click()
      Dim NetR As NETRESOURCE    ' NetResouce structure
      Dim ErrInfo As Long        ' Return value from API
      Dim buffer As String       ' Drive letter assigned to resource
      Dim bufferlen As Long      ' Size of the buffer
      Dim success As Long        ' Additional info about API call
      
      ' Initialize the NetResouce structure
      NetR.dwScope = RESOURCE_GLOBALNET
      NetR.dwType = RESOURCETYPE_DISK
      NetR.dwDisplayType = RESOURCEDISPLAYTYPE_SHARE
      NetR.dwUsage = RESOURCEUSAGE_CONNECTABLE
      NetR.lpLocalName = vbNullString
      NetR.lpRemoteName = txtUNC.Text
   
      ' Initialize the return buffer and buffer size
      buffer = Space(32)
      bufferlen = Len(buffer)
   
      ' Call API to map the drive
      ErrInfo = WNetUseConnection(Me.hWnd, NetR, txtPWD.Text, txtUser.Text, _
         CONNECT_REDIRECT, buffer, bufferlen, success)
   
      ' Check if call to API failed. According to the MSDN help, there
      ' are some versions of the operating system that expect the userid
      ' as the 3rd parameter and the password as the 4th, while other
      ' versions of the operating system have them in reverse order, so
      ' if first call to API fails, try reversing these two parameters.
      If ErrInfo <> NO_ERROR Then
         ' Call API with userid and password switched
         ErrInfo = WNetUseConnection(Me.hWnd, NetR, txtUser.Text, _
            txtPWD.Text, CONNECT_REDIRECT, buffer, bufferlen, success)
      End If
   
      ' Check for success
      If (ErrInfo = NO_ERROR) And (success = CONNECT_LOCALDRIVE) Then
         ' Store the mapped drive letter for later usage
         MappedDrive = Left$(buffer, InStr(1, buffer, ":"))
   
         ' Display the mapped drive letter
         MsgBox "Connect Succeeded to " & MappedDrive
      Else
         MsgBox "ERROR: " & Str(ErrInfo) & " - Connect Failed!"
      End If
   End Sub
   
   Private Sub Command2_Click()
      Dim ErrInfo As Long     ' Return value from API
   
      ' Call API to disconnect the drive
      ErrInfo = WNetCancelConnection2(MappedDrive, _
         CONNECT_UPDATE_PROFILE, False)
   
      ' Check for success
      If ErrInfo = NO_ERROR Then
         MsgBox "Disconnect of '" & MappedDrive & "' Succeeded"
         
         ' Clear the mapped drive letter
         MappedDrive = ""
      Else
         MsgBox "ERROR: " & Str(ErrInfo) & " - Disconnect Failed!"
      End If
   End Sub
   					

6. Save and run the sample.
7. In the first TextBox, type the UNC path to the share you wish to map to a drive letter (such as, \\ServerName\ShareName).
8. In the second TextBox, type your network logon name.
9. In the third TextBox, type your password.
10. Click the CONNECT button.
    
    RESULT: Provided you have typed a valid user id, password, network share, and have the appropriate network permissions, you should receive a message indicating that the share was connected and the mapped drive letter is given. You can verify the map by opening the Windows Explorer.
11. Click the DISCONNECT button.
    
    RESULT: The mapped drive is disconnected. Again, this can be verified with the Windows Explorer.