Mapping a network drive

[chris128]

Unfortunately in the .NET Framework there is currently no way to create a network drive (aka mapped drive) so we have to use a Windows API to accomplish this, the WNetAddConnection2 API to be precise. So I thought I would provide the VB.NET definitions for the API function and the relevant structures/constants, along with a .NET method that you can use to wrap this API functionality to make it easier to use

EDIT: The .NET wrapper for this function and loads of others are all in my .NET Windows API Library which you can download here to save copying and pasting API definitions etc into your projects: http://cjwdev.wordpress.com/2011/06/...-2-2-released/

First of all make sure you use this at the very top of your code:

Imports System.Runtime.InteropServices

then you can copy and paste these API definitions, which I've added comments to just in case you do want to use these directly instead of using the .NET method I will provide later in this post.

'Constants
    Public Const NO_ERROR As UInteger = 0
    Public Const RESOURCETYPE_DISK As UInteger = 1
 
    ''' <summary>
    ''' Creates a connection to a network resource
    ''' </summary>
    ''' <param name="lpNetResource">A NETRESOURCE structure that specifies information about the network resource connection</param>
    ''' <param name="lpPassword">The password to use for the connection - leave blank to use current user credentials</param>
    ''' <param name="lpUserName">The username to use for the connection - leave blank to use current user credentials</param>
    ''' <param name="dwFlags">Bitmask that specifies connection options. For example, whether or not to make the connection persistent</param>
    <DllImportAttribute("mpr.dll", EntryPoint:="WNetAddConnection2W")> _
    Public Shared Function WNetAddConnection2(ByRef lpNetResource As NETRESOURCE, <InAttribute(), MarshalAsAttribute(UnmanagedType.LPWStr)> ByVal lpPassword As String, <InAttribute(), MarshalAsAttribute(UnmanagedType.LPWStr)> ByVal lpUserName As String, ByVal dwFlags As UInteger) As UInteger
    End Function
 
    ''' <summary>
    ''' Contains information about a network resource. Used by the WNetAddConnection2 method
    ''' </summary>
    <StructLayoutAttribute(LayoutKind.Sequential)> _
    Public Structure NETRESOURCE
        Public dwScope As UInteger
        Public dwType As UInteger
        Public dwDisplayType As UInteger
        Public dwUsage As UInteger
        <MarshalAsAttribute(UnmanagedType.LPWStr)> _
        Public lpLocalName As String
        <MarshalAsAttribute(UnmanagedType.LPWStr)> _
        Public lpRemoteName As String
        <MarshalAsAttribute(UnmanagedType.LPWStr)> _
        Public lpComment As String
        <MarshalAsAttribute(UnmanagedType.LPWStr)> _
        Public lpProvider As String
    End Structure

and here is the .NET method I wrote that makes using the API much simpler:

''' <summary>
    ''' Creates a network drive (aka mapped drive) using the specified drive letter, UNC path and optional credentials
    ''' </summary>
    ''' <param name="UncPath">The UNC path (\\servername\share) to map the drive letter to</param>
    ''' <param name="DriveLetter">The drive letter to use</param>
    ''' <param name="Persistent">False to have this drive removed when the user logs off. True to have the drive remembered. 
    ''' This option is the equivelant of the Reconnect At Logon checkbox shown when mapping a drive in Windows Exporer</param>
    ''' <param name="ConnectionUsername">The username to use for the connection - optional</param>
    ''' <param name="ConnectionPassword">The password to use for the connection - optional</param>
    Public Shared Sub MapNetworkDrive(ByVal UncPath As String, ByVal DriveLetter As Char, ByVal Persistent As Boolean, Optional ByVal ConnectionUsername As String = Nothing, Optional ByVal ConnectionPassword As String = Nothing)
        If String.IsNullOrEmpty(UncPath) Then
            Throw New ArgumentException("No UNC path specified", "UncPath")
        End If
        Dim DriveInfo As New NETRESOURCE
        With DriveInfo
            .dwType = RESOURCETYPE_DISK
            .lpLocalName = DriveLetter & ":"
            .lpRemoteName = UncPath
        End With
        Dim flags As UInteger = 0
        If Persistent Then
            flags = &H1
        End If
        Dim Result As UInteger = WNetAddConnection2(DriveInfo, ConnectionPassword, ConnectionUsername, flags)
        If Not Result = NO_ERROR Then
            Throw New System.ComponentModel.Win32Exception(CInt(Result))
        End If
    End Sub

so then when you want to map a network drive you can simply do this:

'This example maps the R drive to \\SomeServer\SomeShare
Try
     MapNetworkDrive("\\SomeServer\SomeShare", "R"c, False)
Catch ex As Exception
     MessageBox.Show("The network drive could not be mapped for the following reason: " & ex.Message)
End Try