Option Explicit

Const ERROR_SUCCESS = 0
Const ERROR_MORE_DATA = 234
Const SV_TYPE_SERVER = &H2
Const SIZE_SI_101 = 24

Private Type SERVER_INFO_101
  dwPlatformId As Long
  lpszServerName As Long
  dwVersionMajor As Long
  dwVersionMinor As Long
  dwType As Long
  lpszComment As Long
End Type

Private Declare Function NetServerEnum Lib "netapi32.dll" (ByVal servername As String, _
  ByVal level As Long, buffer As Long, ByVal prefmaxlen As Long, entriesread As Long, _
  totalentries As Long, ByVal servertype As Long, ByVal domain As String, resumehandle As Long) As Long

Private Declare Function NetApiBufferFree Lib "netapi32.dll" (BufPtr As Any) As Long
Private Declare Sub RtlMoveMemory Lib "KERNEL32" _
  (hpvDest As Any, ByVal hpvSource As Long, ByVal cbCopy As Long)
Private Declare Function lstrcpyW Lib "KERNEL32" _
  (ByVal lpszDest As String, ByVal lpszSrc As Long) As Long

Private Const NERR_Success As Long = 0&
Private Const NERR_BASE = 2100
Private Const NERR_NameNotFound = NERR_BASE + 173
Private Const NERR_NetworkError = NERR_BASE + 36
Private Const ERROR_ACCESS_DENIED = 5
Private Const ERROR_INVALID_PARAMETER = 87
Private Const ERROR_NOT_SUPPORTED = 50

Private Declare Function NetMessageBufferSend Lib "netapi32.dll" (servername As Any, _
  msgname As Byte, fromname As Any, buf As Byte, ByVal buflen As Long) As Long

Private Sub cmdSend_Click()
  Dim nRet As Long
  Dim sTo() As Byte
  Dim sMsg() As Byte

  sTo = lst.List(lst.ListIndex) & Chr(0)
  sMsg = txtMsg & Chr(0)
  nRet = NetMessageBufferSend(ByVal 0, sTo(0), ByVal 0, sMsg(0), UBound(sMsg))
  Select Case nRet
  Case NERR_Success: MsgBox "Success"
  Case NERR_NameNotFound: MsgBox "NameNotFound"
  Case NERR_NetworkError: MsgBox "NetworkError"
  Case ERROR_ACCESS_DENIED: MsgBox "ACCESS_DENIED"
  Case ERROR_INVALID_PARAMETER: MsgBox "INVALID_PARAMETER"
  Case ERROR_NOT_SUPPORTED: MsgBox "NOT_SUPPORTED"
  Case Else: MsgBox "Unexpected error"
  End Select
End Sub

Private Function PointerToString(lpszString As Long) As String
  Dim lpszStr1 As String, lpszStr2 As String, nRet As Long
  lpszStr1 = String(1000, "*")
  nRet = lstrcpyW(lpszStr1, lpszString)
  lpszStr2 = (StrConv(lpszStr1, vbFromUnicode))
  PointerToString = Left(lpszStr2, InStr(lpszStr2, Chr$(0)) - 1)
End Function

Private Sub Form_Load()
  Dim pszServer As String, pszDomain As String
  Dim nLevel As Long, i As Long, BufPtr As Long, TempBufPtr As Long
  Dim nPrefMaxLen As Long, nEntriesRead As Long, nTotalEntries As Long
  Dim nServerType As Long, nResumeHandle As Long, nRet As Long
  Dim ServerInfo As SERVER_INFO_101
  
  nLevel = 101
  BufPtr = 0
  nPrefMaxLen = &HFFFFFFFF
  nEntriesRead = 0
  nTotalEntries = 0
  nServerType = SV_TYPE_SERVER
  nResumeHandle = 0

  Do
    nRet = NetServerEnum(pszServer, nLevel, BufPtr, nPrefMaxLen, nEntriesRead, _
      nTotalEntries, nServerType, pszDomain, nResumeHandle)
    If ((nRet = ERROR_SUCCESS) Or (nRet = ERROR_MORE_DATA)) And (nEntriesRead > 0) Then
      TempBufPtr = BufPtr
      For i = 1 To nEntriesRead
        RtlMoveMemory ServerInfo, TempBufPtr, SIZE_SI_101
        lst.AddItem PointerToString(ServerInfo.lpszServerName)
        TempBufPtr = TempBufPtr + SIZE_SI_101
      Next i
    Else
      MsgBox "NetServerEnum failed: " & nRet
    End If
    NetApiBufferFree (BufPtr)
  Loop While nEntriesRead < nTotalEntries
End Sub