Accessing Network Resources

[raresm79]

Hi!

i'm trying to read a file using default share in c#. Is there a method to send the username/password to the remote machine that have the necessary rights to access the default share and read the file. I did this under VC++ with the WNetAddConnection() function.But i can't find anything like this in C#.

Please advice....
Thx...Rares

[Aleksej]

Hi,
As far as I know, there're only System.Net to provide socket interface. So for more complicated functions like WNetAddconnection() from <winsock.h> or <winsock2.h> you should use P/Invoke

[raresm79]

Thanks a lot for ur answer. I don't want to use only WNetAddConnection. I would like to know if there is a method in .Net that can give me access to a network resource by providing a username and password that have access to that resource.

Cheers

[stepi]

Hi there,
To answer your question i don't know a method that will do that for you.You will need to impersonate the user prior to accessing your network shared resources:

                using System.Security.Principal;
                using System.Runtime.InteropServices;
                .....................
		#region Impersonate

		public const int LOGON32_LOGON_INTERACTIVE = 2;
		public const int LOGON32_PROVIDER_DEFAULT = 0;
		WindowsImpersonationContext impersonationContext;

		[DllImport("advapi32.dll")]
		public static extern int LogonUserA(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);

		private bool impersonateValidUser(String userName, String domain, String password)
		{
			WindowsIdentity tempWindowsIdentity;
			IntPtr token = IntPtr.Zero;
			IntPtr tokenDuplicate = IntPtr.Zero;

			if(RevertToSelf())
			{
				if(LogonUserA(userName, domain, password, LOGON32_LOGON_INTERACTIVE,
					LOGON32_PROVIDER_DEFAULT, ref token) != 0)
				{
					if(DuplicateToken(token, 2, ref tokenDuplicate) != 0)
					{
						tempWindowsIdentity = new WindowsIdentity(tokenDuplicate);
						impersonationContext = tempWindowsIdentity.Impersonate();
						if (impersonationContext != null)
						{
							CloseHandle(token);
							CloseHandle(tokenDuplicate);
							return true;
						}
					}
					else
					{

					}
				}
				else
				{

				}
			}
			else
			{

			}
			if(token!= IntPtr.Zero)
				CloseHandle(token);
			if(tokenDuplicate!=IntPtr.Zero)
				CloseHandle(tokenDuplicate);
			return false;
		}

		private void undoImpersonation()
		{
			impersonationContext.Undo();
		}
		#endregion		

                ..................................
                if(impersonateValidUser(USER_NAME, DOMAIN, PASSWORD))
		{
			//here you can have your code for reading your file
			undoImpersonation();
		}