How To Use NetQueryDisplayInformation() in Visual Basic (316318)


The information in this article applies to:

  • Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows 4.0, when used with:
    • the operating system: Microsoft Windows XP
    • the operating system: Microsoft Windows 2000
    • the operating system: Microsoft Windows NT 4.0
  • Microsoft Visual Basic Professional Edition, 32-bit, for Windows 4.0, when used with:
    • the operating system: Microsoft Windows XP
    • the operating system: Microsoft Windows 2000
    • the operating system: Microsoft Windows NT 4.0
This article was previously published under Q316318

SUMMARY

The sample code in this article demonstrates how to use the NetQueryDisplayInformation function to enumerate users, machines, and groups that are available in the specified domain in a 32-bit Visual Basic application.

NOTE: The 32-bit version of the NetQueryDisplayInformation function is only supported in Microsoft Windows NT or later. This function uses Unicode for its string parameters.

MORE INFORMATION

When you call C functions in Visual Basic, you must redefine or declare the relevant constants, structures(types), and functional prototypes. The sample code in this article demonstrates how to use NetQueryDisplayInformation at the following levels:
  • Level 1 (NET_DISPLAY_USER) to enumerate all of the users in the specified domain.
  • Level 2 (NET_DISPLAY_MACHINE) to enumerate all of the servers that are present in the specified domain.
  • Level 3 (NET_DISPLAY_GROUP) to enumerate all of the groups that are present in the specified domain.
You must also declare the prototypes for NetQueryDisplayInformation and the memory management functions, such as the NetApiBufferFree, the RtlMoveMemory, and the lstrcpyW functions.

Use this Visual Basic code sample to create a Visual Basic form that includes the following components:
  • One list box named List1. List1 displays the list of users, servers, or groups.
  • Two text boxes named txtPageSize and txtTotal. The txtPageSize text box displays the number of data per page, and the txtTotal text box displays the total number of items in the list.
  • Two command buttons named btnRun and btnExit. The btnRun button executes the NetQueryDisplayInformation function, and the btnExit button closes the application.
  • One frame named Frame1. In Frame1, you can select whether you want to display users, machines, or groups.
'/* definitions and declarations
Private Declare Function NetQueryDisplayInformation Lib "netapi32.dll" _
        (ByVal lpwServername As String, _
        ByVal dwLevel As Long, _
        ByVal dwIndex As Long, _
        ByVal dwReqEntries As Long, _
        ByVal dwMaxLength As Long, _
        pdwNumEntries As Long, _
        pBuffer As Any) As Long

Private Declare Function NetApiBufferFree Lib "netapi32.dll" (BufPtr As Any) As Long

Private Declare Sub CopyMem Lib "KERNEL32" Alias "RtlMoveMemory" ( _
        hpvDest As Any, ByVal hpvSource As Long, ByVal cbCopy As Long)


Private Declare Function CopyString Lib "KERNEL32" Alias "lstrcpyW" ( _
        ByVal NewString As String, ByVal OldString As Long) As Long
        

Private Const NET_USER = 1
Private Const NET_MACHINE = 2
Private Const NET_GROUP = 3
Private Const ERROR_MORE_DATA = 234
Private Const REQUESTED_ENTRIES = 5
Private Const MAX_PREFERRED_LENGTH = &HFFFF

Private Type NET_DISPLAY_USER
    usri1_name As Long      'lpwstr
    usri1_comment As Long   'lpwstr
    usri1_flags As Long
    usri1_full_name As Long 'lpwstr
    usri1_user_id As Long
    usri1_next_index As Long
End Type

Private Type NET_DISPLAY_GROUP
    grpi3_name As Long      'lpwstr
    grpi3_comment As Long   'lpwstr
    grpi3_group_id As Long
    grpi3_attributes As Long
    grpi3_next_index As Long
End Type

Private Type NET_DISPLAY_MACHINE
    usri2_name As Long      'lpwstr
    usri2_comment As Long   'lpwstr
    usri2_flags As Long
    usri2_user_id As Long
    usri2_next_index As Long
End Type

Private Sub btnExit_Click()
    Unload Me
End Sub

Private Sub btnRun_Click()
    '/* This code enumerates domain users.
    Dim pndu() As NET_DISPLAY_USER
    Dim pndm() As NET_DISPLAY_MACHINE
    Dim pndg() As NET_DISPLAY_GROUP
    Dim pszTemp As String, pszServer As String
    Dim pBuffer As Long
    Dim lLevel As Long
    Dim lResult As Long
    Dim lIndex As Long
    Dim lNumEntries As Long
    Dim lTotalEntries As Long
    
    List1.Clear
    
    ' Get the domain controller name. It can be a null string.
    pszTemp = Chr(0)
    pszTemp = InputBox("Enter domain controller name: (eg. \\domain-01)", "DC Name")
    If Len(pszTemp) = 0 Then
        pszServer = vbNullString
    Else
        pszServer = StrConv(pszTemp, vbUnicode)
    End If
    
    lIndex = 0
    lTotalEntries = 0
    lNumEntries = 0
    lResult = ERROR_MORE_DATA
    
    If (txtPageSize < 1) Then
        txtPageSize = REQUESTED_ENTRIES
    End If
    
    If (optUser = True) Then
        While lResult = ERROR_MORE_DATA
            List1.AddItem "---------------"
            lResult = NetQueryDisplayInformation(pszServer, NET_USER, lIndex, _
                        txtPageSize, MAX_PREFERRED_LENGTH, lNumEntries, pBuffer)
         
            If lResult = 0 Or lResult = ERROR_MORE_DATA Then
                If lNumEntries > 0 Then
                    ReDim pndu(lNumEntries - 1)
                    '/* Copy information to VB friendly structure
                    CopyMem pndu(0), ByVal pBuffer, Len(pndu(0)) * lNumEntries
                    
                    For i = 0 To lNumEntries - 1
                        List1.AddItem PointerToString(pndu(i).usri1_name)
                    Next
                    
                    '/* Get index for next iteration
                    lIndex = pndu(i - 1).usri1_next_index
                End If
            Else
                MsgBox "Error: " & lResult
            End If
            
            If pBuffer Then
                '/* Release NetAPI buffer
                NetApiBufferFree (pBuffer)
            End If
            
            lTotalEntries = lNumEntries + lTotalEntries
        Wend
    ElseIf (optMachine = True) Then
        While lResult = ERROR_MORE_DATA
            List1.AddItem "---------------"
            lResult = NetQueryDisplayInformation(pszServer, NET_MACHINE, lIndex, _
                        txtPageSize, MAX_PREFERRED_LENGTH, lNumEntries, pBuffer)
         
            If lResult = 0 Or lResult = ERROR_MORE_DATA Then
                If lNumEntries > 0 Then
                    ReDim pndm(lNumEntries - 1)
                    '/* Copy information to VB friendly structure
                    CopyMem pndm(0), ByVal pBuffer, Len(pndm(0)) * lNumEntries
                    
                    For i = 0 To lNumEntries - 1
                        List1.AddItem PointerToString(pndm(i).usri2_name)
                    Next
                    
                    '/* Get index for next iteration
                    lIndex = pndm(i - 1).usri2_next_index
                End If
            Else
                MsgBox "Error: " & lResult
            End If
            
            If pBuffer Then
                '/* Release NetAPI buffer.
                NetApiBufferFree (pBuffer)
            End If
            
            lTotalEntries = lNumEntries + lTotalEntries
        Wend
    ElseIf (optGroup = True) Then
        While lResult = ERROR_MORE_DATA
            List1.AddItem "---------------"
            lResult = NetQueryDisplayInformation(pszServer, NET_GROUP, lIndex, _
                        txtPageSize, MAX_PREFERRED_LENGTH, lNumEntries, pBuffer)
         
            If lResult = 0 Or lResult = ERROR_MORE_DATA Then
                If lNumEntries > 0 Then
                    ReDim pndg(lNumEntries - 1)
                    '/* Copy information to VB friendly structure
                    CopyMem pndg(0), ByVal pBuffer, Len(pndg(0)) * lNumEntries
                    
                    For i = 0 To lNumEntries - 1
                        List1.AddItem PointerToString(pndg(i).grpi3_name)
                    Next
                    
                    '/* Get index for next iteration
                    lIndex = pndg(i - 1).grpi3_next_index
                End If
            Else
                MsgBox "Error: " & lResult
            End If
            
            If pBuffer Then
                '/* Release NetAPI buffer.
                NetApiBufferFree (pBuffer)
            End If
            
            lTotalEntries = lNumEntries + lTotalEntries
        Wend
    Else
        MsgBox "Invalid level!"
    End If

    txtTotal.Text = lTotalEntries
End Sub

Private Function PointerToString(lpszString As Long) As String
    Dim Temp1 As String, res As Long, Temp2 As String
    Temp1 = String(1000, "*")
    res = CopyString(Temp1, lpszString)
    Temp2 = (StrConv(Temp1, vbFromUnicode))
    PointerToString = Left(Temp2, InStr(Temp2, Chr$(0)) - 1)
End Function

REFERENCES

For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:

159498 How To Call LanMan Services from 32-bit Visual Basic Apps

159423 How To Call LAN Manager Functions from 16-bit Visual Basic 4.0

151774 How To Call NetUserGetInfo from Visual Basic

106553 How To Write C DLLs and Call Them from Visual Basic

118643 How to Pass a String or String Arrays Between VB and a C DLL

Modification Type:MinorLast Reviewed:8/30/2004
Keywords:kbDSWNET2003Swept kbAPI kbhowto kbinfo KB316318
©2004 Microsoft Corporation. All rights reserved.