Impersonation

Impersonation

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using System.Security.Principal;

public class UserImpersonator : IDisposable
{

    [DllImport("advapi32.dll", SetLastError = true)]
    private static extern int LogonUser(
        string lpszUserName,
        string lpszDomain,
        string lpszPassword,
        int dwLogonType,
        int dwLogonProvider,
        ref IntPtr phToken);

    [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern int DuplicateToken(
        IntPtr hToken,
        int impersonationLevel,
        ref IntPtr hNewToken);

    [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern bool RevertToSelf();

    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    private static extern bool CloseHandle(
    IntPtr handle);

    private const int LOGON32_LOGON_INTERACTIVE = 2;
    private const int LOGON32_PROVIDER_DEFAULT = 0;
    enum LogonType
    {
        Interactive = 2,
        Network = 3,
        Batch = 4,
        Service = 5,
        Unlock = 7,
        NetworkClearText = 8,
        NewCredentials = 9
    }
    enum LogonProvider
    {
        Default = 0,
        WinNT35 = 1,
        WinNT40 = 2,
        WinNT50 = 3
    }

    // If you incorporate this code into a DLL, be sure to demand that it
    // runs with FullTrust.

    public UserImpersonator(string userPrincipalName, string password)
    {
        var spn = userPrincipalName.Split('@');

        string userName = spn[0];
        string domainName = spn[1];

        Impersonate(domainName, userName, password);
    }

    public UserImpersonator(string domainName, string userName, string password)
    {
        Impersonate(domainName, userName, password);
    }

    [PermissionSetAttribute(SecurityAction.Demand, Name = "FullTrust")]
    public void Impersonate(string domainName, string userName, string password)
    {
        WindowsIdentity tempWindowsIdentity = null;
        IntPtr token = IntPtr.Zero;
        IntPtr tokenDuplicate = IntPtr.Zero;

        try
        {
            if (RevertToSelf())
            {
                if (LogonUser(
                userName,
                domainName,
                password,
                    //(int)LogonType.NewCredentials,
                    //(int)LogonProvider.WinNT50,
                (int)LogonType.Interactive,
                (int)LogonProvider.Default,

                //LOGON32_LOGON_INTERACTIVE,
                    //LOGON32_PROVIDER_DEFAULT,
                ref token) != 0)
                {
                    if (DuplicateToken(token, 2, ref tokenDuplicate) != 0)
                    {
                        tempWindowsIdentity = new WindowsIdentity(tokenDuplicate);
                        impersonationContext = tempWindowsIdentity.Impersonate();
                    }
                    else
                    {
                        throw new Win32Exception(Marshal.GetLastWin32Error());
                    }
                }
                else
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            else
            {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }
        }
        finally
        {
            if (token != IntPtr.Zero)
            {
                CloseHandle(token);
            }
            if (tokenDuplicate != IntPtr.Zero)
            {
                CloseHandle(tokenDuplicate);
            }
        }
    }

    /// 
    /// Reverts the impersonation.
    /// 
    private void UndoImpersonation()
    {
        if (impersonationContext != null)
        {
            impersonationContext.Undo();
        }
    }

    private WindowsImpersonationContext impersonationContext = null;

    // Stops impersonation
    public void Dispose()
    {
        UndoImpersonation();
    }
}

public interface IElevatedUser : IDisposable
{

    IElevatedUser Impersonate();
    IElevatedUser Impersonate(string account, string password);

    string Account
    {
        get;
        set;
    }

    string Password
    {
        get;
        set;
    }

}

public class ElevatedUser : IElevatedUser
{

    private UserImpersonator impersonator;

    public ElevatedUser()
    {
    }

    public IElevatedUser Impersonate()
    {
        return Impersonate(Account, Password);
    }

    public IElevatedUser Impersonate(string account, string password)
    {
        if (account == null)
        {
            throw new ArgumentNullException("account", "Account not set.");
        }
        if (password == null)
        {
            throw new ArgumentNullException("password", "Password not set.");
        }
        this.impersonator = new UserImpersonator(account, password);
        return this;
    }

    public void Dispose()
    {
        impersonator.Dispose();
    }

    public string Account
    {
        get;
        set;
    }

    public string Password
    {
        get;
        set;
    }
}