Accessing mapped drives while impersonating in ASP.NET

Short version: Is it possible to use impersonation in ASP.NET to access mapped drives?

Long version:

I am currently using impersonation in ASP.NET to access network files. This works fine for any network file using a UNC path, but it doesn't have access to any files on the mapped drives defined for the user account I issued.

For example, suppose a file lives on the network at \\machine\folder\file.txt

, and let's also say that the drive is S:

mapped to \\machine\folder

. We need to have access to the full path of the UNC, \\machine\folder\file.txt

, as well as a shorter route to the map S:\file.txt

.

Obviously the standard ASP.NET process cannot access.

Using a console application that runs under a local account with a mapped drive S:

, the call File.Exists(@"\\machine\folder\file.txt")

returns true and File.Exists(@"S:\file.txt")

also returns true.

However, when impersonating in the ASP.NET context with the same local account, it only File.Exists(@"\\machine\folder\file.txt")

returns true. File.Exists(@"S:\file.txt")

returns false.

I am testing with IIS 7 running on my local windows 7 box, but this should work in both IIS 6 and IIS 7.

Impersonation is handled by several classes in C #, which I will include here:

public static class Impersonation
{
    private static WindowsImpersonationContext context;

    public static void ImpersonateUser(string username, string password)
    {
        ImpersonateUser(".", username, password);
    }

    public static void ImpersonateUser(string domain, string username, string password)
    {
        StopImpersonating();

        IntPtr userToken;
        var returnValue = ImpersonationImports.LogonUser(username, domain, password,
                                                  ImpersonationImports.LOGON32_LOGON_INTERACTIVE,
                                                  ImpersonationImports.LOGON32_PROVIDER_DEFAULT,
                                                  out userToken);
        context = WindowsIdentity.Impersonate(userToken);
    }

    public static void StopImpersonating()
    {
        if (context != null)
        {
            context.Undo();
            context = null;
        }
    }
}

public static class ImpersonationImports
{
    public const int LOGON32_LOGON_INTERACTIVE = 2;
    public const int LOGON32_LOGON_NETWORK = 3;
    public const int LOGON32_LOGON_BATCH = 4;
    public const int LOGON32_LOGON_SERVICE = 5;
    public const int LOGON32_LOGON_UNLOCK = 7;
    public const int LOGON32_LOGON_NETWORK_CLEARTEXT = 8;
    public const int LOGON32_LOGON_NEW_CREDENTIALS = 9;
    public const int LOGON32_PROVIDER_DEFAULT = 0;

    [DllImport("advapi32.dll", SetLastError = true)]
    public static extern int LogonUser(
        string lpszUsername,
        string lpszDomain,
        string lpszPassword,
        int dwLogonType,
        int dwLogonProvider,
        out IntPtr phToken
        );
    [DllImport("advapi32.dll", SetLastError = true)]
    public static extern int ImpersonateLoggedOnUser(
        IntPtr hToken
    );

    [DllImport("advapi32.dll", SetLastError = true)]
    public static extern int RevertToSelf();

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern int CloseHandle(IntPtr hObject);
}

      

        
        
        
      

    

Then during Page_Load we basically do something like this:

Impersonation.ImpersonateUser("DOMAIN", "username", "password");

if (!File.Exists(@"S:\file.txt"))
     throw new WeCannotContinueException();

      

        
        
        
      

    

I understand that using mapped drives is not best practice, but for old reasons it is desirable for our business. Can I use impersonation in ASP.NET to access mapped drives?