The Below Code Provides a mechanism for supplying a list of all PC names in the local network.
This class makes use of a DllImport instruction. The purpose of which is as follows:
When a DllImport declaration is made in managed code (C#) it is a call to a legacy
unmanaged code module, normally a C++ Dynamic Link Library. These C++ Dll's are
usually part of the operating system API, or some other vendors API, and must be
used to carry out operations that are not native within the managed code C# framework.
This is fairly normal within the windows world. The only thing that needs careful consideration
is the construction of the correct type of STRUCTS, object pointers, and attribute markers,
which all contribute to making the link between managed (C#) and unmanaged code (C++)
more seamless
Netapi32.dll : NetServerEnum, The NetServerEnum function lists all servers
of the specified type that are visible in a domain. For example, an application can call
NetServerEnum to list all domain controllers only or all SQL servers only.
You can combine bit masks to list several types. For example, a value of 0x00000003
combines the bit masks for SV_TYPE_WORKSTATION (0x00000001) and SV_TYPE_SERVER (0x00000002).
Netapi32.dll : NetApiBufferFree, The NetApiBufferFree function frees
the memory that the NetApiBufferAllocate function allocates. Call NetApiBufferFree
to free the memory that other network management functions return.</description>
At first create a class with name 'claMachineAccess'
#Region "Dll Imports"
'declare the Netapi32 : NetServerEnum method import
''' <summary>
''' Netapi32.dll : The NetServerEnum function lists all servers
''' of the specified type that are visible in a domain. For example, an
''' application can call NetServerEnum to list all domain controllers only
''' or all SQL servers only.
''' You can combine bit masks to list several types. For example, a value
''' of 0x00000003 combines the bit masks for SV_TYPE_WORKSTATION
''' (0x00000001) and SV_TYPE_SERVER (0x00000002)
''' </summary>
' must be null
' null for login domain
<DllImport("Netapi32", CharSet:=CharSet.Auto, SetLastError:=True), SuppressUnmanagedCodeSecurityAttribute> _
Public Shared Function NetServerEnum(ServerNane As String, dwLevel As Integer, ByRef pBuf As IntPtr, dwPrefMaxLen As Integer, ByRef dwEntriesRead As Integer, ByRef dwTotalEntries As Integer, _
dwServerType As Integer, domain As String, ByRef dwResumeHandle As Integer) As Integer
End Function
'declare the Netapi32 : NetApiBufferFree method import
''' <summary>
''' Netapi32.dll : The NetApiBufferFree function frees
''' the memory that the NetApiBufferAllocate function allocates.
''' Call NetApiBufferFree to free the memory that other network
''' management functions return.
''' </summary>
<DllImport("Netapi32", SetLastError:=True), SuppressUnmanagedCodeSecurityAttribute> _
Public Shared Function NetApiBufferFree(pBuf As IntPtr) As Integer
End Function
'create a _SERVER_INFO_100 STRUCTURE
<StructLayout(LayoutKind.Sequential)> _
Public Structure _SERVER_INFO_100
Friend sv100_platform_id As Integer
<MarshalAs(UnmanagedType.LPWStr)> _
Friend sv100_name As String
End Structure
#End Region
#Region "Public Constructor"
''' <summary>
''' Constructor, simply creates a new NetworkBrowser object
''' </summary>
Public Sub New()
End Sub
#End Region
#Region "Public Methods"
''' <summary>
''' Uses the DllImport : NetServerEnum with all its required parameters
''' (see http://msdn.microsoft.com/library/default.asp?url=/library/en-us/netmgmt/netmgmt/netserverenum.asp
''' for full details or method signature) to retrieve a list of domain SV_TYPE_WORKSTATION
''' and SV_TYPE_SERVER PC's
''' </summary>
''' <returns>Arraylist that represents all the SV_TYPE_WORKSTATION and SV_TYPE_SERVER
''' PC's in the Domain</returns>
Public Function getNetworkComputers() As ArrayList
'local fields
Dim networkComputers As New ArrayList()
Const MAX_PREFERRED_LENGTH As Integer = -1
Dim SV_TYPE_WORKSTATION As Integer = 1
Dim SV_TYPE_SERVER As Integer = 2
Dim buffer As IntPtr = IntPtr.Zero
Dim tmpBuffer As IntPtr = IntPtr.Zero
Dim entriesRead As Integer = 0
Dim totalEntries As Integer = 0
Dim resHandle As Integer = 0
Dim sizeofINFO As Integer = Marshal.SizeOf(GetType(_SERVER_INFO_100))
Try
'call the DllImport : NetServerEnum with all its required parameters
'see http://msdn.microsoft.com/library/default.asp?url=/library/en-us/netmgmt/netmgmt/netserverenum.asp
'for full details of method signature
Dim ret As Integer = NetServerEnum(Nothing, 100, buffer, MAX_PREFERRED_LENGTH, entriesRead, totalEntries, _
SV_TYPE_WORKSTATION Or SV_TYPE_SERVER, Nothing, resHandle)
'if the returned with a NERR_Success (C++ term), =0 for C#
If ret = 0 Then
'loop through all SV_TYPE_WORKSTATION and SV_TYPE_SERVER PC's
For i As Integer = 0 To totalEntries - 1
'get pointer to, Pointer to the buffer that received the data from
'the call to NetServerEnum. Must ensure to use correct size of
'STRUCTURE to ensure correct location in memory is pointed to
tmpBuffer = New IntPtr(CInt(buffer) + (i * sizeofINFO))
'Have now got a pointer to the list of SV_TYPE_WORKSTATION and
'SV_TYPE_SERVER PC's, which is unmanaged memory
'Needs to Marshal data from an unmanaged block of memory to a
'managed object, again using STRUCTURE to ensure the correct data
'is marshalled
Dim svrInfo As _SERVER_INFO_100 = CType(Marshal.PtrToStructure(tmpBuffer, GetType(_SERVER_INFO_100)), _SERVER_INFO_100)
'add the PC names to the ArrayList
networkComputers.Add(svrInfo.sv100_name)
Next
End If
Catch ex As Exception
MessageBox.Show("Problem with acessing network computers in NetworkBrowser " & vbCr & vbLf & vbCr & vbLf & vbCr & vbLf & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.[Error])
Return Nothing
Finally
'The NetApiBufferFree function frees
'the memory that the NetApiBufferAllocate function allocates
NetApiBufferFree(buffer)
End Try
'return entries found
Return networkComputers
End Function
#End Region
End Class
After Creating the class just right the following code to access the computer name :
hare CBox_IP is a conbo box which will display all the Pc
Dim nb As New ScanClientCredential()
For Each pc As String In nb.getNetworkComputers()
CBox_IP.Items.Add(pc)
Next
