C#: How to logon to a share when using DirectoryInfo

Question

If I want to instantiate a DirectoryInfo object with an UNC path

DirectoryInfo myDI = new DirectoryInfo (@\"\\\\server\\share\");

how can

Answer 1

Try this approach:

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

namespace Tools.Network
{
 public enum LogonType
 {
  LOGON32_LOGON_INTERACTIVE = 2,
  LOGON32_LOGON_NETWORK = 3,
  LOGON32_LOGON_BATCH = 4,
  LOGON32_LOGON_SERVICE = 5,
  LOGON32_LOGON_UNLOCK = 7,
  LOGON32_LOGON_NETWORK_CLEARTEXT = 8, // Win2K or higher
  LOGON32_LOGON_NEW_CREDENTIALS = 9 // Win2K or higher
 };

 public enum LogonProvider
 {
  LOGON32_PROVIDER_DEFAULT = 0,
  LOGON32_PROVIDER_WINNT35 = 1,
  LOGON32_PROVIDER_WINNT40 = 2,
  LOGON32_PROVIDER_WINNT50 = 3
 };

 public enum ImpersonationLevel
 {
  SecurityAnonymous = 0,
  SecurityIdentification = 1,
  SecurityImpersonation = 2,
  SecurityDelegation = 3
 }

 class Win32NativeMethods
 {
  [DllImport("advapi32.dll", SetLastError = true)]
  public 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)]
  public static extern int DuplicateToken( IntPtr hToken,
        int impersonationLevel,
        ref IntPtr hNewToken);

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

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

 /// 

 /// Allows code to be executed under the security context of a specified user account.
 /// 
 ///  
 ///
 /// Implements IDispose, so can be used via a using-directive or method calls;
 ///  ...
 ///
 ///  var imp = new Impersonator( "myUsername", "myDomainname", "myPassword" );
 ///  imp.UndoImpersonation();
 ///
 ///  ...
 ///
 ///   var imp = new Impersonator();
 ///  imp.Impersonate("myUsername", "myDomainname", "myPassword");
 ///  imp.UndoImpersonation();
 ///
 ///  ...
 ///
 ///  using ( new Impersonator( "myUsername", "myDomainname", "myPassword" ) )
 ///  {
 ///   ...
 ///   [code that executes under the new context]
 ///   ...
 ///  }
 ///
 ///  ...
 /// 
 public class Impersonator : IDisposable
 {
  private WindowsImpersonationContext _wic;

  /// 

  /// Begins impersonation with the given credentials, Logon type and Logon provider.
  /// 
  ///
Name of the user.
  ///
Name of the domain.
  ///
The password. 
  ///
Type of the logon.
  ///
The logon provider. 
  public Impersonator(string userName, string domainName, string password, LogonType logonType, LogonProvider logonProvider)
  {
   Impersonate(userName, domainName, password, logonType, logonProvider);
  }

  /// 

  /// Begins impersonation with the given credentials.
  /// 
  ///
Name of the user.
  ///
Name of the domain.
  ///
The password. 
  public Impersonator(string userName, string domainName, string password)
  {
   Impersonate(userName, domainName, password, LogonType.LOGON32_LOGON_INTERACTIVE, LogonProvider.LOGON32_PROVIDER_DEFAULT);
  }

  /// 

  /// Initializes a new instance of the  class.
  /// 
  public Impersonator()
  {}

  /// 

  /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
  /// 
  public void Dispose()
  {
   UndoImpersonation();
  }

  /// 

  /// Impersonates the specified user account.
  /// 
  ///
Name of the user.
  ///
Name of the domain.
  ///
The password. 
  public void Impersonate(string userName, string domainName, string password)
  {
   Impersonate(userName, domainName, password, LogonType.LOGON32_LOGON_INTERACTIVE, LogonProvider.LOGON32_PROVIDER_DEFAULT);
  }

  /// 

  /// Impersonates the specified user account.
  /// 
  ///
Name of the user.
  ///
Name of the domain.
  ///
The password. 
  ///
Type of the logon.
  ///
The logon provider. 
  public void Impersonate(string userName, string domainName, string password, LogonType logonType, LogonProvider logonProvider)
  {
   UndoImpersonation();

   IntPtr logonToken = IntPtr.Zero;
   IntPtr logonTokenDuplicate = IntPtr.Zero;
   try
   {
    // revert to the application pool identity, saving the identity of the current requestor
    _wic = WindowsIdentity.Impersonate(IntPtr.Zero);

    // do logon & impersonate
    if (Win32NativeMethods.LogonUser(userName,
        domainName,
        password,
        (int)logonType,
        (int)logonProvider,
        ref logonToken) != 0)
    {
     if (Win32NativeMethods.DuplicateToken(logonToken, (int)ImpersonationLevel.SecurityImpersonation, ref logonTokenDuplicate) != 0)
     {
      var wi = new WindowsIdentity(logonTokenDuplicate);
      wi.Impersonate(); // discard the returned identity context (which is the context of the application pool)
     }
     else
      throw new Win32Exception(Marshal.GetLastWin32Error());
    }
    else
     throw new Win32Exception(Marshal.GetLastWin32Error());
   }
   finally
   {
    if (logonToken != IntPtr.Zero)
     Win32NativeMethods.CloseHandle(logonToken);

    if (logonTokenDuplicate != IntPtr.Zero)
     Win32NativeMethods.CloseHandle(logonTokenDuplicate);
   }
  }

  /// 

  /// Stops impersonation.
  /// 
  private void UndoImpersonation()
  {
   // restore saved requestor identity
   if (_wic != null)
    _wic.Undo();
   _wic = null;
  }
 }
}