C-Sharp .Net 1.1

How to Use `Net Use` in C# with Exception Handling

If you’re a C# developer, you might find yourself needing to map or disconnect network drives without resorting to command line tools. The built-in Net Use command is fantastic, but calling it from your application can feel clunky and less elegant. Fortunately, there’s a solution that lets you achieve this directly in C# using the P/Invoke method. In this post, we’ll explore how to map and disconnect network drives in C#, while also implementing robust exception handling.

Why Use P/Invoke?

P/Invoke, or Platform Invocation Services, is a feature of the .NET Framework that allows managed code to call unmanaged functions implemented in DLLs. This means that instead of relying on command line calls, we can directly interact with system-level network functions. This provides greater flexibility and more control over error handling.

Implementing the Solution

To manage network drives in C#, we’ll use the WNetAddConnection2 function, which is part of the Windows API. This function allows you to map a network drive dynamically within your C# application.

Step 1: Define the Necessary Structures and Constants

Before we call the API, we need to define some structures and constants that the WNetAddConnection2 function requires. Here’s a quick overview:

using System.Runtime.InteropServices;

[StructLayout(LayoutKind.Sequential)]
public struct NETRESOURCE
{
    public int dwType;
    public string lpProvider;
    public string lpDevice;
    public string lpRemoteName;
    public string lpLocalName;
    public string lpPassword;
    public string lpUsername;
}

public const int RESOURCETYPE_DISK = 1;
public const int CONNECT_UPDATE_PROFILE = 0x00000001;

The NETRESOURCE structure contains all the necessary parameters for the network resource we want to connect or disconnect from.
The RESOURCETYPE_DISK constant specifies that we are dealing with disk resources.

Step 2: Create the P/Invoke Call

Next, we need to create a method that calls WNetAddConnection2. Here’s how you can encapsulate this in a function:

[DllImport("mpr.dll")]
public static extern int WNetAddConnection2(NETRESOURCE lpNetResource, string lpPassword, string lpUsername, int dwFlags);

public void MapNetworkDrive(string driveLetter, string networkPath, string username, string password)
{
    NETRESOURCE netResource = new NETRESOURCE
    {
        dwType = RESOURCETYPE_DISK,
        lpLocalName = driveLetter,
        lpRemoteName = networkPath,
        lpProvider = null
    };

    int result = WNetAddConnection2(netResource, password, username, CONNECT_UPDATE_PROFILE);
    
    if (result != 0)
    {
        throw new System.ComponentModel.Win32Exception(result);
    }
}

This function, MapNetworkDrive, will allow you to map a drive by passing the local drive letter, the network path, and credentials.

Step 3: Implement Exception Handling

To ensure our application can gracefully handle errors, we can wrap our mapping logic inside a try-catch block:

try
{
    MapNetworkDrive("Z:", @"\\NetworkPath\Share", "username", "password");
    Console.WriteLine("Network drive mapped successfully!");
}
catch (System.ComponentModel.Win32Exception ex)
{
    Console.WriteLine($"Error mapping network drive: {ex.Message}");
}

If any issue occurs during the connection, an exception will be thrown, and we can handle it appropriately, informing the user of the failure.

Disconnecting a Network Drive

To disconnect a network drive, you can use the WNetCancelConnection2 function, which operates similarly to the WNetAddConnection2 function. You will have to define this function using P/Invoke as well, follow a similar process to the above, and handle exceptions similarly.

In Summary

Using P/Invoke to manage network drives in C# provides a cleaner solution compared to invoking the command line’s Net Use feature. Here’s a quick recap of the steps:

Use the WNetAddConnection2 function to map network drives.
Handle all relevant parameters and structures through P/Invoke.
Implement robust exception handling to gracefully respond to issues.

By following this guide, you can effectively manage network drives within your C# applications, ensuring smooth functionality and a better user experience. Always remember, Google is your friend – you can find additional wrappers and examples out there to simplify your implementation!

How to Use Net Use in C# with Exception Handling