Reverse mapping of drive letter to server address

You need the pure server address of a remote directory mapped to a drive letter? Try this:

[DllImport("Mpr.dll", CharSet = CharSet.Auto)]
private static extern int WNetGetConnection(
    [MarshalAs(UnmanagedType.LPTStr)] string localName,
    [MarshalAs(UnmanagedType.LPTStr)] StringBuilder remoteName,
    ref int length);

public static String GetServerPath(char driverLetter)
{
    try
    {
        int length = 1024;
        StringBuilder result = new StringBuilder(length);
        WNetGetConnection(driverLetter + ":", result, ref length);

        return result.ToString();
    }
    catch
    {
    }
    return null;
}

public static String GetServerPath(String filename)
{
    if (filename.Length > 1 && filename[1] == ':')
    {
        String serverpath = GetServerPath(filename[0]);
        if (serverpath != null && serverpath.Trim().Length > 0)
            filename = serverpath + filename.Substring(2);
    }
    return filename;
}