HOWTO: Call LanMan Services from 32-bit Visual Basic Apps

Last reviewed: September 29, 1997
Article ID: Q159498

The information in this article applies to:

Standard, Professional, and Enterprise Editions of Microsoft Visual Basic, 32-bit only, for Windows, version 4.0

SUMMARY

This article demonstrates how to call various LanMan services from 32-bit Visual Basic 4.0 applications. The sample code also applies to applications which use the 32-bit VBA engine. An example of such an application is Microsoft Excel 97.

MORE INFORMATION

Windows NT exposes LanMan 32-bit Application Programming Interfaces (APIs) to provide network services. These APIs are called only from 32-bit programs running on a Windows NT workstation or server and are used to control both the local and remote Windows NT machines that you have permission to access.

This article contains code examples of using the following LanMan APIs:

   NetGetDCName
   NetUserDel
   NetGroupAddUser
   NetGroupDelUser
   NetUserAdd        (using Level 1 structure)
   NetUserEnum       (using Level 0 structure)
   NetGroupEnumUsers (using Level 0 structure)
   NetGroupEnum      (using Level 0 structure)
   NetUserGetGroups  (using Level 0 structure)
   NetAPIBufferFree
   NetAPIBufferAllocate

Although, Visual Basic stores strings internally as UNICODE, it converts them to ANSI when it calls APIs. Normally this isn't a problem because most 32-bit APIs have both an ANSI and a UNICODE version. However, LanMan APIs only support UNICODE. The code snippet below demonstrates how to use Byte arrays to pass UNICODE parameters.

Instead of using strings, for example:

   "X = My_ANSI_API("Some String")"

use Byte arrays, such the one below, because they aren't converted to ANSI:

   Dim Temp() As Byte, Message As String
   Message = "Some String"
   Temp = Message & vbNullChar     '
   MyUnicodeAPI Temp(0)
   Message = Temp                  ' modified message

Declarations and Sample Code

WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN RISK. Microsoft provides this macro code "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. Microsoft provides examples of Visual Basic procedures for illustration only, without warranty either expressed or implied, including, but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. The Visual Basic procedures in this article are provided 'as is' and Microsoft does not guarantee that they can be used in all situations. While Microsoft support engineers can help explain the functionality of a particular procedure, they will not modify these examples to provide added functionality, nor will they help you construct procedures to meet your specific needs. If you have limited programming experience, you may want to consult one of the Microsoft Solution Providers. Solution Providers offer a wide range of fee-based services, including creating custom procedures. For more information about Microsoft Solution Providers, call Microsoft Customer Information Service at (800) 426-9400.

   Option Explicit
   Option Base 0     ' Important assumption for this code

   Type MungeLong
     X As Long
     Dummy As Integer
   End Type

   Type MungeInt
     XLo As Integer
     XHi As Integer
     Dummy As Integer
   End Type

   Type TUser0                    ' Level 0
     ptrName As Long
   End Type

   Type TUser1                    ' Level 1
     ptrName As Long
     ptrPassword As Long
     dwPasswordAge As Long
     dwPriv As Long
     ptrHomeDir As Long
     ptrComment As Long
     dwFlags As Long
     ptrScriptPath As Long
   End Type

   '
   ' for dwPriv
   '
   Const USER_PRIV_MASK = &H3
   Const USER_PRIV_GUEST = &H0
   Const USER_PRIV_USER = &H1
   Const USER_PRIV_ADMIN = &H2

   '
   ' for dwFlags
   '
   Const UF_SCRIPT = &H1
   Const UF_ACCOUNTDISABLE = &H2
   Const UF_HOMEDIR_REQUIRED = &H8
   Const UF_LOCKOUT = &H10
   Const UF_PASSWD_NOTREQD = &H20
   Const UF_PASSWD_CANT_CHANGE = &H40
   Const UF_NORMAL_ACCOUNT = &H200     ' Needs to be ORed with the
                                       ' other flags

   '
   ' for lFilter
   '
   Const FILTER_NORMAL_ACCOUNT = &H2

   Declare Function NetGetDCName Lib "NETAPI32.DLL" (ServerName As Byte, _
   DomainName As Byte, DCNPtr As Long) As Long

   Declare Function NetUserDel Lib "NETAPI32.DLL" (ServerName As Byte, _
   UserName As Byte) As Long

   Declare Function NetGroupAddUser Lib "NETAPI32.DLL" (ServerName As _
   Byte, GroupName As Byte, UserName As Byte) As Long

   Declare Function NetGroupDelUser Lib "NETAPI32.DLL" (ServerName As _
   Byte, GroupName As Byte, UserName As Byte) As Long

   ' Add using Level 1 user structure
   Declare Function NetUserAdd1 Lib "NETAPI32.DLL" Alias "NetUserAdd" _
   (ServerName As Byte, ByVal Level As Long, Buffer As TUser1, ParmError _
   As Long) As Long

   ' Enumerate using Level 0 user structure
   Declare Function NetUserEnum0 Lib "NETAPI32.DLL" Alias "NetUserEnum" _
   (ServerName As Byte, ByVal Level As Long, ByVal lFilter As Long, _
   Buffer As Long, ByVal PrefMaxLen As Long, EntriesRead As Long, _
   TotalEntries As Long, ResumeHandle As Long) As Long

   Declare Function NetGroupEnumUsers0 Lib "NETAPI32.DLL" Alias _
   "NetGroupGetUsers" (ServerName As Byte, GroupName As Byte, _
   ByVal Level As Long, Buffer As Long, ByVal PrefMaxLen As Long, _
   EntriesRead As Long, TotalEntries As Long, ResumeHandle As Long) As Long

   Declare Function NetGroupEnum0 Lib "NETAPI32.DLL" Alias "NetGroupEnum" _
   (ServerName As Byte, ByVal Level As Long, Buffer As Long, ByVal _
   PrefMaxLen As Long, EntriesRead As Long, TotalEntries As Long, _
   ResumeHandle As Long) As Long

   Declare Function NetUserGetGroups0 Lib "NETAPI32.DLL" Alias _
   "NetUserGetGroups" (ServerName As Byte, UserName As Byte, _
   ByVal Level As Long, Buffer As Long, ByVal PrefMaxLen As Long, _
   EntriesRead As Long, TotalEntries As Long) As Long

   Declare Function NetAPIBufferFree Lib "NETAPI32.DLL" Alias _
   "NetApiBufferFree" (ByVal Ptr As Long) As Long

   Declare Function NetAPIBufferAllocate Lib "NETAPI32.DLL" Alias _
   "NetApiBufferAllocate" (ByVal ByteCount As Long, Ptr As Long) As Long

   Declare Function PtrToStr Lib "Kernel32" Alias "lstrcpyW" _
   (RetVal As Byte, ByVal Ptr As Long) As Long

   Declare Function StrToPtr Lib "Kernel32" Alias "lstrcpyW" _
   (ByVal Ptr As Long, Source As Byte) As Long

   Declare Function PtrToInt Lib "Kernel32" Alias "lstrcpynW" _
   (RetVal As Any, ByVal Ptr As Long, ByVal nCharCount As Long) As Long

   Declare Function StrLen Lib "Kernel32" Alias "lstrlenW" _
   (ByVal Ptr As Long) As Long

   Function AddUserToGroup(ByVal SName As String, _
   ByVal GName As String, ByVal UName As String) As Long
   '
   ' This only adds users to global groups - not to local groups
   '
   Dim SNArray() As Byte, GNArray() As Byte, UNArray() As Byte, _
   Result As Long
     SNArray = SName & vbNullChar
     GNArray = GName & vbNullChar
     UNArray = UName & vbNullChar
     Result = NetGroupAddUser(SNArray(0), GNArray(0), UNArray(0))
     If Result = 2220 Then Debug.Print _
   "There is no **GLOBAL** group '" & GName & "'"
     AddUserToGroup = Result
   End Function

   Function DelUser(ByVal SName As String, ByVal UName As String) As Long
   Dim UNArray() As Byte, SNArray() As Byte
     UNArray = UName & vbNullChar
     SNArray = SName & vbNullChar
     DelUser = NetUserDel(SNArray(0), UNArray(0))
   End Function

   Function DelUserFromGroup(ByVal SName As String, _
   ByVal GName As String, ByVal UName As String) As Long
   '
   ' This only deletes users from global groups - not local groups
   '
   Dim SNArray() As Byte, GNArray() As Byte, UNArray() As Byte, _
   Result As Long
     SNArray = SName & vbNullChar
     GNArray = GName & vbNullChar
     UNArray = UName & vbNullChar
     Result = NetGroupDelUser(SNArray(0), GNArray(0), UNArray(0))
     If Result = 2220 Then Debug.Print _
   "There is no **GLOBAL** group '" & GName & "'"
     DelUserFromGroup = Result
   End Function

   Function EnumerateGroups(ByVal SName As String, _
   ByVal UName As String) As Long
   '
   ' Enumerates global groups only - not local groups
   '
   ' The buffer is filled from the left with pointers to user names that
   ' are filled from the right side. For example:
   '
   '     ptr1|ptr2|...|ptrn|<garbage>|strn|...|str2|str1
   '     ^-------------- BufPtr buffer ----------------^
   '
   ' On NT, TotalEntries is the number of entries left to be read including
   ' the currently read entries.
   '
   ' On LanMan and OS/2, it is the total number of entries, period. Code
   ' would have to be changed to reflect this if the Domain controller
   ' wasn't an NT machine.
   '
   ' BufPtr gets the address of the buffer (or ptr1 - add 4 to BufPtr for
   ' each additional pointer)
   '
   Dim Result As Long, BufPtr As Long, EntriesRead As Long, _
   TotalEntries As Long, ResumeHandle As Long, BufLen As Long, _
   SNArray() As Byte, GNArray(99) As Byte, UNArray() As Byte, _
   GName As String, I As Integer, UNPtr As Long, _
   TempPtr As MungeLong, TempStr As MungeInt

     SNArray = SName & vbNullChar       ' Move to byte array
     UNArray = UName & vbNullChar       ' Move to Byte array
     BufLen = 255                       ' Buffer size
     ResumeHandle = 0                   ' Start with the first entry

     Do
       If UName = "" Then
         Result = NetGroupEnum0(SNArray(0), 0, BufPtr, BufLen, _
   EntriesRead, TotalEntries, ResumeHandle)
       Else
         Result = NetUserGetGroups0(SNArray(0), UNArray(0), 0, BufPtr, _
   BufLen, EntriesRead, TotalEntries)
       End If
       EnumerateGroups = Result
       If Result <> 0 And Result <> 234 Then    ' 234 means multiple reads
                                                ' required
         Debug.Print "Error " & Result & " enumerating group " & _
   EntriesRead & " of " & TotalEntries
         Exit Function
       End If
       For I = 1 To EntriesRead
         ' Get pointer to string from beginning of buffer
         ' Copy 4 byte block of memory in 2 steps
         Result = PtrToInt(TempStr.XLo, BufPtr + (I - 1) * 4, 2)
         Result = PtrToInt(TempStr.XHi, BufPtr + (I - 1) * 4 + 2, 2)
         LSet TempPtr = TempStr ' munge 2 Integers to a Long
         ' Copy string to array and convert to a string
         Result = PtrToStr(GNArray(0), TempPtr.X)
         GName = Left(GNArray, StrLen(TempPtr.X))
         Debug.Print "Group: " & GName
       Next I
     Loop Until EntriesRead = TotalEntries
   ' The above condition only valid for reading accounts on NT
   ' but not OK for OS/2 or LanMan

     Result = NetAPIBufferFree(BufPtr)         ' Don't leak memory

   End Function

   Function EnumerateUsers(ByVal SName As String, ByVal GName As String) _
   As Long
   '
   ' If a group name is specified, it must be a global group
   ' and not a local group.
   '
   ' The buffer is filled from the left with pointers to user names that
   ' are filled from the right side. For example:
   '
   '     ptr1|ptr2|...|ptrn|<garbage>|strn|...|str2|str1
   '     ^-------------- BufPtr buffer ----------------^
   '
   ' On Windows NT, TotalEntries is the number of entries left to be read,
   ' including the currently read entries.
   ' On LanMan and OS/2, it is the total number of entries, period.  Code
   ' would have to be changed to reflect this if the Domain controller
   ' wasn't an NT machine.
   '
   ' BufPtr gets the address of the buffer (or ptr1 - add 4 to BufPtr for
   ' each additional pointer)
   '
   ' SName should be "\\servername"
   '
   Dim Result As Long, BufPtr As Long, EntriesRead As Long, _
   TotalEntries As Long, ResumeHandle As Long, BufLen As Long, _
   SNArray() As Byte, GNArray() As Byte, UNArray(99) As Byte, _
   UName As String, I As Integer, UNPtr As Long, TempPtr As MungeLong, _
   TempStr As MungeInt

     SNArray = SName & vbNullChar       ' Move to byte array
     GNArray = GName & vbNullChar       ' Move to Byte array
     BufLen = 255                       ' Buffer size
     ResumeHandle = 0                   ' Start with the first entry

     Do
       If GName = "" Then
         Result = NetUserEnum0(SNArray(0), 0, FILTER_NORMAL_ACCOUNT, _
   BufPtr, BufLen, EntriesRead, TotalEntries, ResumeHandle)
       Else
         Result = NetGroupEnumUsers0(SNArray(0), GNArray(0), 0, BufPtr, _
   BufLen, EntriesRead, TotalEntries, ResumeHandle)
       End If
       EnumerateUsers = Result
       If Result <> 0 And Result <> 234 Then    ' 234 means multiple reads
                                                ' required
         Debug.Print "Error " & Result & " enumerating user " _
   & EntriesRead & " of " & TotalEntries
         If Result = 2220 Then Debug.Print _
   "There is no **GLOBAL** group '" & GName & "'"
         Exit Function
       End If
       For I = 1 To EntriesRead
         ' Get pointer to string from beginning of buffer
         ' Copy 4-byte block of memory in 2 steps
         Result = PtrToInt(TempStr.XLo, BufPtr + (I - 1) * 4, 2)
         Result = PtrToInt(TempStr.XHi, BufPtr + (I - 1) * 4 + 2, 2)
         LSet TempPtr = TempStr ' munge 2 integers into a Long
         ' Copy string to array
         Result = PtrToStr(UNArray(0), TempPtr.X)
         UName = Left(UNArray, StrLen(TempPtr.X))
         Debug.Print "User: " & UName
       Next I
     Loop Until EntriesRead = TotalEntries
   ' The above condition is only valid for reading accounts on Windows NT,
   ' but is not OK for OS/2 or LanMan

     Result = NetAPIBufferFree(BufPtr)         ' Don't leak memory

   End Function

   Function GetPrimaryDCName(ByVal MName As String, _
   ByVal DName As String) As String
   Dim Result As Long, DCName As String, DCNPtr As Long
   Dim DNArray() As Byte, MNArray() As Byte, DCNArray(100) As Byte
     MNArray = MName & vbNullChar
     DNArray = DName & vbNullChar
     Result = NetGetDCName(MNArray(0), DNArray(0), DCNPtr)
     If Result <> 0 Then
       Debug.Print "Error: " & Result
       Exit Function
     End If
     Result = PtrToStr(DCNArray(0), DCNPtr)
     Result = NetAPIBufferFree(DCNPtr)
     DCName = DCNArray()
     GetPrimaryDCName = DCName
   End Function

   Function AddUser(ByVal SName As String, ByVal UName As String, _
   ByVal PWD As String) As Long
   Dim Result As Long, UNPtr As Long, PWDPtr As Long, ParmError As Long
   Dim SNArray() As Byte, UNArray() As Byte, PWDArray() As Byte
   Dim UserStruct As TUser1
   '
   ' Move to byte arrays
   '
     SNArray = SName & vbNullChar
     UNArray = UName & vbNullChar
     PWDArray = PWD & vbNullChar
   '
   ' Allocate buffer space
   '
     Result = NetAPIBufferAllocate(UBound(UNArray) + 1, UNPtr)
     Result = NetAPIBufferAllocate(UBound(PWDArray) + 1, PWDPtr)
   '
   ' Copy arrays to the buffer
   '
     Result = StrToPtr(UNPtr, UNArray(0))
     Result = StrToPtr(PWDPtr, PWDArray(0))
   '
   ' Fill the structure
   '
     With UserStruct
       .ptrName = UNPtr
       .ptrPassword = PWDPtr
       .dwPasswordAge = 3
       .dwPriv = USER_PRIV_USER
       .ptrHomeDir = 0
       .ptrComment = 0
       .dwFlags = UF_NORMAL_ACCOUNT Or UF_SCRIPT
       .ptrScriptPath = 0
     End With
   '
   ' Add the user
   '
     Result = NetUserAdd1(SNArray(0), 1, UserStruct, ParmError)
     AddUser = Result
     If Result <> 0 Then
       Debug.Print "Error " & Result & " in parameter " & ParmError _
   & " when adding user " & UName
     End If
   '
   ' Release buffers from memory
   '
     Result = NetAPIBufferFree(UNPtr)
     Result = NetAPIBufferFree(PWDPtr)

   End Function

Keywords          : APrgOther vb432 VB4WIN vbwin
Technology        : kbvba
Version           : WINDOWS:4.0
Platform          : WINDOWS
Issue type        : kbhowto

================================================================================

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Last reviewed: September 29, 1997
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.