Visual Basic Network Services
NetShareEnum: Enumerating Shared Resources on Other Machines
Posted:   Monday June 25, 2001
Updated:   Monday December 26, 2011
Applies to:   VB4-32, VB5, VB6
Developed with:   VB6, Windows 2000
OS restrictions:   Windows NT3.1, Windows NT4, Windows 2000, Windows XP
Author:   VBnet - Randy Birch


WNetAddConnection2: Transparently Connect to Network Shares
NetShareCheck: Determine Remote Folder or Device Share Status
WNetEnumResource: Enumerating Local Network Resources
NetConnectionEnum: Enumerating Share Connection Information
NetShareEnum: Enumerating Shared Resources on Other Machines  
NetShareAdd: Create a Local or Remote Share
WNetGetUser: User, Share and Share User for Network Resources
WNetGetConnection: Get UNC Path for Mapped Drive

For this demo, one of the operating systems listed under OS Restrictions above.

NetShareEnum retrieves information about each shared resource on a server. It's security requirements are the same as those outlined in NetWkstaUserEnum: Workstation Logon Information.

WNetEnumResource can also be used to retrieve resource information, however, it does not enumerate hidden shares or users connected to a share. The demo below shows how to call NetShareEnum with the SHARE_INFO_2 structure when calling on an NT-based machine. WNetEnumResource can be called on 9x and NT-based systems (WNetEnumResource: Enumerating Local Network Resources).

The parameters for NetShareEnum under Windows 95/98/Me - including the structures you can use - are different from those valid for Windows NT/2000/XP. Specifically, the MSDN states that in using this API for 9x, the calling application must use the cbBuffer parameter to specify the size, in bytes, of the information buffer pointed to by the pbBuffer parameter. (The cbBuffer parameter replaces the prefmaxlen parameter.) In addition, the resume handle parameter is not available on this platform. Therefore, for 9x systems the API's parameter list is defined as:

   const char FAR * pszServer, 
   short sLevel, 
   char FAR * pbBuffer, 
   unsigned short cbBuffer, 
   unsigned short FAR * pcEntriesRead, 
   unsigned short FAR * pcTotalAvail );

The MSDN's NetShareEnum page contains a link to a C code example for calling this API under Windows 95/98/Me.

 BAS Module Code

 Form Code
To a form add a command button (Command1), list box (List1), and two labels (Label1, Label2). A third set of labels in a control array can be used for the list item captions. Add the following to the form:

Option Explicit
' Copyright 1996-2011 VBnet/Randy Birch, All Rights Reserved.
' Some pages may also contain other copyrights by the author.
' Distribution: You can freely use this code in your own
'               applications, but you may not reproduce 
'               or publish this code on any web site,
'               online service, or distribute as source 
'               on any media without express permission.
'Windows type used to call the Net API
Private Const MAX_PREFERRED_LENGTH As Long = -1
Private Const NERR_SUCCESS As Long = 0&
Private Const ERROR_MORE_DATA As Long = 234&
Private Const LB_SETTABSTOPS As Long = &H192

'See NetServerEnum demo for complete
'list of server types supported
Private Const SV_TYPE_ALL As Long = &HFFFFFFFF
Private Const SV_TYPE_WORKSTATION As Long = &H1
Private Const SV_TYPE_SERVER As Long = &H2

Private Const STYPE_ALL As Long = -1  'note: my const
Private Const STYPE_DISKTREE As Long = 0
Private Const STYPE_PRINTQ As Long = 1
Private Const STYPE_DEVICE As Long = 2
Private Const STYPE_IPC As Long = 3
Private Const STYPE_SPECIAL As Long = &H80000000
Private Const ACCESS_READ  As Long = &H1
Private Const ACCESS_WRITE As Long = &H2
Private Const ACCESS_CREATE As Long = &H4
Private Const ACCESS_EXEC As Long = &H8
Private Const ACCESS_DELETE As Long = &H10
Private Const ACCESS_ATRIB As Long = &H20
Private Const ACCESS_PERM As Long = &H40
Private Const ACCESS_ALL As Long = ACCESS_READ Or _
                                   ACCESS_WRITE Or _
                                   ACCESS_CREATE Or _
                                   ACCESS_EXEC Or _
                                   ACCESS_DELETE Or _
                                   ACCESS_ATRIB Or _
'for use on Win NT/2000 only
Private Type SERVER_INFO_100
  sv100_platform_id As Long
  sv100_name As Long
End Type

'shi2_current_uses: number of current connections to the resource
'shi2_max_uses    : max concurrent connections resource can accommodate
'shi2_netname     : share name of a resource
'shi2_passwd      : share's password when
'                  (server running with share-level security)
'shi2_path        : local path for the shared resource
'shi2_permissions : shared resource's permissions
'                  (servers running with share-level security)
'shi2_remark      : string containing optional comment about the resource
'shi2_type        : the type of the shared resource
Private Type SHARE_INFO_2
  shi2_netname As Long
  shi2_type As Long
  shi2_remark As Long
  shi2_permissions As Long
  shi2_max_uses As Long
  shi2_current_uses As Long
  shi2_path As Long
  shi2_passwd As Long
End Type

Private Declare Function NetServerEnum Lib "netapi32" _
  (ByVal servername As Long, _
   ByVal level As Long, _
   buf As Any, _
   ByVal prefmaxlen As Long, _
   entriesread As Long, _
   totalentries As Long, _
   ByVal servertype As Long, _
   ByVal domain As Long, _
   resume_handle As Long) As Long

Private Declare Function NetShareEnum Lib "netapi32" _
  (ByVal servername As Long, _
   ByVal level As Long, _
   bufptr As Long, _
   ByVal prefmaxlen As Long, _
   entriesread As Long, _
   totalentries As Long, _
   resume_handle As Long) As Long
Private Declare Function NetApiBufferFree Lib "netapi32" _
   (ByVal Buffer As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32" _
   Alias "RtlMoveMemory" _
  (pTo As Any, uFrom As Any, _
   ByVal lSize As Long)
Private Declare Function lstrlenW Lib "kernel32" _
  (ByVal lpString As Long) As Long

Private Declare Function SendMessage Lib "user32" _
   Alias "SendMessageA" _
  (ByVal hwnd As Long, _
   ByVal wMsg As Long, _
   ByVal wParam As Long, _
   lParam As Any) As Long

Private Sub Form_Load()

   ReDim TabArray(0 To 4) As Long
   TabArray(0) = 73
   TabArray(1) = 125
   TabArray(2) = 151
   TabArray(3) = 232
  'Clear any existing tabs
  'and set the list tabstops
   Call SendMessage(List1.hwnd, LB_SETTABSTOPS, 0&, ByVal 0&)
   Call SendMessage(List1.hwnd, LB_SETTABSTOPS, 4&, TabArray(0))
   Command1.Caption = "Net Share Enum"
   Label1.Caption = "call success (0) or error :"
   Label2.Caption = ""

End Sub

Private Sub Command1_Click()

   Dim bufptr          As Long  'output
   Dim dwServer        As Long  'pointer to the server
   Dim dwEntriesread   As Long  'out
   Dim dwTotalentries  As Long  'out
   Dim dwResumehandle  As Long  'out
   Dim success         As Long
   Dim nStructSize     As Long
   Dim cnt             As Long
   Dim usrname         As String
   Dim bServer         As String
   Dim shi2            As SHARE_INFO_2
  'demo using the local machine
   bServer = "\\" & Environ$("COMPUTERNAME") & vbNullString
  'create pointer to the machine name
   dwServer = StrPtr(bServer)
   success = NetShareEnum(dwServer, _
                          2, _
                          bufptr, _
                          MAX_PREFERRED_LENGTH, _
                          dwEntriesread, _
                          dwTotalentries, _

   Label2.Caption = success
   If success = NERR_SUCCESS And _
      success <> ERROR_MORE_DATA Then
      nStructSize = LenB(shi2)
      For cnt = 0 To dwEntriesread - 1
        'get one chunk of data and cast
        'into an SHARE_INFO_2 type, and
        'add the data to a list
         CopyMemory shi2, ByVal bufptr + (nStructSize * cnt), nStructSize

         List1.AddItem GetPointerToByteStringW(shi2.shi2_netname) & vbTab & _
                       GetConnectionType(shi2.shi2_type) & vbTab & _
                       GetConnectionPermissions(shi2.shi2_permissions) & vbTab & _
                       GetPointerToByteStringW(shi2.shi2_remark) & vbTab & _
                       GetPointerToByteStringW(shi2.shi2_path)  ' & vbTab & _

   End If
   Call NetApiBufferFree(bufptr)

End Sub

Private Function GetConnectionPermissions(ByVal dwPermissions As Long) As String

  'Permissions are only returned a shared
  'resource running with share-level security.
  'A server running user-level security ignores
  'this member, so the function returns
  '"not applicable".
   Dim tmp As String
   If (dwPermissions And ACCESS_READ) Then tmp = tmp & "R"
   If (dwPermissions And ACCESS_WRITE) Then tmp = tmp & " W"
   If (dwPermissions And ACCESS_CREATE) Then tmp = tmp & " C"
   If (dwPermissions And ACCESS_DELETE) Then tmp = tmp & " D"
   If (dwPermissions And ACCESS_EXEC) Then tmp = tmp & " E"
   If (dwPermissions And ACCESS_ATRIB) Then tmp = tmp & " A"
   If (dwPermissions And ACCESS_PERM) Then tmp = tmp & " P"

   If Len(tmp) = 0 Then tmp = "n/a"
   GetConnectionPermissions = tmp
End Function

Private Function GetConnectionType(ByVal dwConnectType As Long) As String

  'compare connection type value
   Select Case dwConnectType
      Case STYPE_DISKTREE: GetConnectionType = "disk drive"
      Case STYPE_PRINTQ:   GetConnectionType = "print queue"
      Case STYPE_DEVICE:   GetConnectionType = "communication device"
      Case STYPE_IPC:      GetConnectionType = "ipc"
      Case STYPE_SPECIAL:  GetConnectionType = "administrative"
      Case Else
        'weird case. On my NT2000 machines,
        'I have to do this to identify the
        'IPC$ share type
         Select Case (dwConnectType Xor STYPE_SPECIAL) 'rtns 3 if IPC
            Case STYPE_IPC: GetConnectionType = "ipc"
            Case Else:      GetConnectionType = "undefined"
         End Select
   End Select
End Function

Public Function GetPointerToByteStringW(ByVal dwData As Long) As String
   Dim tmp() As Byte
   Dim tmplen As Long
   If dwData <> 0 Then
      tmplen = lstrlenW(dwData) * 2
      If tmplen <> 0 Then
         ReDim tmp(0 To (tmplen - 1)) As Byte
         CopyMemory tmp(0), ByVal dwData, tmplen
         GetPointerToByteStringW = tmp
     End If
   End If
End Function


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