DOCUMENT:Q177697 05-DEC-1997 [vbwin] TITLE :HOWTO: List Local Network Connections with WNetEnumResources PRODUCT :Microsoft Visual Basic for Windows PROD/VER:WINDOWS:4.0,5.0,95; WINNT:3.51,4.0 OPER/SYS:WINDOWS winnt KEYWORDS:VB4WIN vb5all vb5howto ====================================================================== --------------------------------------------------------------------- The information in this article applies to: - Microsoft Visual Basic Professional and Enterprise Editions for Windows, versions 4.0, 5.0 - Microsoft Windows NT versions 3.51, 4.0 - Microsoft Windows 95 - Microsoft Win32 Software Development Kit (SDK) --------------------------------------------------------------------- SUMMARY ======= WNetOpenEnum and WNetEnumResources can be used to list the local drives, printer ports that have been redirected, and any UNC connections on a machine running Windows NT or Windows 95. The code below demonstrates how to do this from Visual Basic by first calling WNetOpenEnum with the dwType parameter set to RESOURCETYPE_ANY. A valid handle returned via the last parameter is passed to WNetEnumResources. This function fills a temporary buffer with an array of NETRESOURCE structures, which includes information about the local network connections. Note that this functionality will not list the resources that are redirected on a remote machine. No such functionality exists in either operating system. MORE INFORMATION ================ The sample includes one form and one module. Follow the steps below to create it. 1. Create a new project and add the following code to the form: Option Explicit Private Const GMEM_FIXED = &H0 Private Const GMEM_ZEROINIT = &H40 Private Const GPTR = (GMEM_FIXED Or GMEM_ZEROINIT) Private Declare Function GlobalAlloc Lib "KERNEL32" ( _ ByVal wFlags As Long, ByVal dwBytes As Long) As Long Private Declare Function GlobalFree Lib "KERNEL32" ( _ ByVal hMem As Long) As Long Private Declare Sub CopyMemory Lib "KERNEL32" Alias "RtlMoveMemory" ( _ hpvDest As Any, hpvSource As Any, ByVal cbCopy As Long) Private Declare Function CopyPointer2String Lib "KERNEL32" _ Alias "lstrcpyA" ( _ ByVal NewString As String, ByVal OldString As Long) As Long Private Sub Form_click() Dim hEnum As Long, lpBuff As Long, nr As NETRESOURCE Dim cbBuff As Long, cCount As Long Dim p As Long, res As Long, i As Long 'Setup the NETRESOURCE input structure nr.dwUsage = RESOURCEUSAGE_CONTAINER nr.lpRemoteName = 0 cbBuff = 1000 cCount = &HFFFFFFFF 'Open a Net enumeration operation handle: hEnum res = WNetOpenEnum(RESOURCE_CONNECTED, RESOURCETYPE_ANY, _ 0, nr, hEnum) If res = 0 Then 'Create a buffer large enough for the results. '1000 bytes should be sufficient lpBuff = GlobalAlloc(GPTR, cbBuff) 'Call the enumeration function res = WNetEnumResource(hEnum, cCount, lpBuff, cbBuff) If res = 0 Then p = lpBuff Cls 'WNetEnumResource fills the buffer with an array of NETRESOURCE 'structures. Walk through the list and print each local and 'remote name For i = 1 To cCount CopyMemory nr, ByVal p, LenB(nr) p = p + LenB(nr) Print PointerToString(nr.lpLocalName), _ PointerToString(nr.lpRemoteName) Next i Else MsgBox "Error: " & Err.LastDllError, vbOKOnly, _ "WNetEnumResources" End If If lpBuff <> 0 Then GlobalFree (lpBuff) WNetCloseEnum (hEnum) 'Close the enumeration Else MsgBox "Error: " & Err.LastDllError, vbOKOnly, "WNetOpenEnum" End If End Sub Private Function PointerToString(p As Long) As String 'The values returned in the NETRESOURCE structures are pointers to 'ANSI strings so they need to be converted to Visual Basic Strings Dim s As String s = String(255, Chr$(0)) CopyPointer2String s, p PointerToString = Left(s, InStr(s, Chr$(0)) - 1) End Function 2. Add a new module to the project and add the following code: Option Explicit Public Type NETRESOURCE dwScope As Long dwType As Long dwDisplayType As Long dwUsage As Long lpLocalName As Long lpRemoteName As Long lpComment As Long lpProvider As Long End Type Public Declare Function WNetOpenEnum Lib "mpr.dll" Alias _ "WNetOpenEnumA" ( _ ByVal dwScope As Long, _ ByVal dwType As Long, _ ByVal dwUsage As Long, _ lpNetResource As Any, _ lphEnum As Long) As Long Public Declare Function WNetEnumResource Lib "mpr.dll" Alias _ "WNetEnumResourceA" ( _ ByVal hEnum As Long, _ lpcCount As Long, _ ByVal lpBuffer As Long, _ lpBufferSize As Long) As Long Public Declare Function WNetCloseEnum Lib "mpr.dll" ( _ ByVal hEnum As Long) As Long ' RESOURCE ENUMERATION Public Const RESOURCE_CONNECTED = &H1 Public Const RESOURCE_GLOBALNET = &H2 Public Const RESOURCE_REMEMBERED = &H3 Public Const RESOURCETYPE_ANY = &H0 Public Const RESOURCETYPE_DISK = &H1 Public Const RESOURCETYPE_PRINT = &H2 Public Const RESOURCETYPE_UNKNOWN = &HFFFF Public Const RESOURCEUSAGE_CONNECTABLE = &H1 Public Const RESOURCEUSAGE_CONTAINER = &H2 Public Const RESOURCEUSAGE_RESERVED = &H80000000 3. Execute the program. When you click on the form, a list of all the local network connections should be displayed, along with the shares they are connected to. ====================================================================== Keywords : VB4WIN vb5all vb5howto Version : WINDOWS:4.0,5.0,95; WINNT:3.51,4.0 Platform : WINDOWS winnt Issue type : kbhowto ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 1997.