NegotiateStream Classe

Definição

public ref class NegotiateStream : System::Net::Security::AuthenticatedStream

public class NegotiateStream : System.Net.Security.AuthenticatedStream

type NegotiateStream = class
    inherit AuthenticatedStream

Public Class NegotiateStream
Inherits AuthenticatedStream

Herança

Object

MarshalByRefObject

Stream

AuthenticatedStream

NegotiateStream

Exemplos

O exemplo seguinte demonstra o lado cliente de uma ligação cliente-servidor que utiliza o NegotiateStream. O cliente autentica e envia uma mensagem ao servidor de forma assíncrona.

using System;
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Text;

namespace Examples.NegotiateStreamExample
{
    public class ASynchronousAuthenticatingTcpClient
    {
        static TcpClient client = null;

        public static void Main(String[] args)
        {
            // Establish the remote endpoint for the socket.
            // For this example, use the local machine.
            IPHostEntry ipHostInfo = Dns.GetHostEntry("localhost");
            IPAddress ipAddress = ipHostInfo.AddressList[0];
            // Client and server use port 11000.
            IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);
            // Create a TCP/IP socket.
            client = new TcpClient();
            // Connect the socket to the remote endpoint.
            client.Connect(remoteEP);
            Console.WriteLine("Client connected to {0}.", remoteEP.ToString());
            // Ensure the client does not close when there is
            // still data to be sent to the server.
            client.LingerState = new LingerOption(true, 0);
            // Request authentication.
            NetworkStream clientStream = client.GetStream();
            NegotiateStream authStream = new NegotiateStream(clientStream, false);
            // Pass the NegotiateStream as the AsyncState object
            // so that it is available to the callback delegate.
            Task authenticateTask = authStream
                .AuthenticateAsClientAsync()
                .ContinueWith(task =>
                {
                    Console.WriteLine("Client ending authentication...");
                    Console.WriteLine("ImpersonationLevel: {0}", authStream.ImpersonationLevel);
                });

            Console.WriteLine("Client waiting for authentication...");
            // Wait until the result is available.
            authenticateTask.Wait();
            // Display the properties of the authenticated stream.
            AuthenticatedStreamReporter.DisplayProperties(authStream);
            // Send a message to the server.
            // Encode the test data into a byte array.
            byte[] message = Encoding.UTF8.GetBytes("Hello from the client.");
            Task writeTask = authStream
                .WriteAsync(message, 0, message.Length)
                .ContinueWith(task =>
                {
                    Console.WriteLine("Client ending write operation...");
                });

            writeTask.Wait();
            Console.WriteLine("Sent {0} bytes.", message.Length);
            // Close the client connection.
            authStream.Close();
            Console.WriteLine("Client closed.");
        }
    }

    // The following class displays the properties of an authenticatedStream.
    public class AuthenticatedStreamReporter
    {
        public static void DisplayProperties(AuthenticatedStream stream)
        {
            Console.WriteLine("IsAuthenticated: {0}", stream.IsAuthenticated);
            Console.WriteLine("IsMutuallyAuthenticated: {0}", stream.IsMutuallyAuthenticated);
            Console.WriteLine("IsEncrypted: {0}", stream.IsEncrypted);
            Console.WriteLine("IsSigned: {0}", stream.IsSigned);
            Console.WriteLine("IsServer: {0}", stream.IsServer);
        }
    }
}

Imports System.Text
Imports System.Net.Sockets
Imports System.Net.Security
Imports System.Net

Namespace Examples.NegotiateStreamExample

    Public Class ASynchronousAuthenticatingTcpClient

        Shared client As TcpClient = Nothing

        Public Shared Sub Main(args As String())
            ' Establish the remote endpoint for the socket.
            ' For this example, use the local machine.
            Dim ipHostInfo = Dns.GetHostEntry("localhost")
            Dim ipAddress = ipHostInfo.AddressList(0)

            ' Client and server use port 11000. 
            Dim remoteEP As New IPEndPoint(ipAddress, 11000)

            ' Create a TCP/IP socket.
            client = New TcpClient()

            ' Connect the socket to the remote endpoint.
            client.Connect(remoteEP)
            Console.WriteLine("Client connected to {0}.", remoteEP.ToString())

            ' Ensure the client does not close when there is 
            ' still data to be sent to the server.
            client.LingerState = (New LingerOption(True, 0))

            ' Request authentication.
            Dim clientStream = client.GetStream()
            Dim authStream As New NegotiateStream(clientStream, False)

            ' Pass the NegotiateStream as the AsyncState object 
            ' so that it is available to the callback delegate.
            Dim ar = authStream.BeginAuthenticateAsClient(
                New AsyncCallback(AddressOf EndAuthenticateCallback), authStream)

            Console.WriteLine("Client waiting for authentication...")

            ' Wait until the result is available.
            ar.AsyncWaitHandle.WaitOne()

            ' Display the properties of the authenticated stream.
            AuthenticatedStreamReporter.DisplayProperties(authStream)

            ' Send a message to the server.
            ' Encode the test data into a byte array.
            Dim message = Encoding.UTF8.GetBytes("Hello from the client.")
            ar = authStream.BeginWrite(message, 0, message.Length, 
                New AsyncCallback(AddressOf EndWriteCallback), authStream)
            ar.AsyncWaitHandle.WaitOne()
            Console.WriteLine("Sent {0} bytes.", message.Length)

            ' Close the client connection.
            authStream.Close()
            Console.WriteLine("Client closed.")

        End Sub

        ' The following method is called when the authentication completes.
        Public Shared Sub EndAuthenticateCallback(ar As IAsyncResult)

            Console.WriteLine("Client ending authentication...")
            Dim authStream = CType(ar.AsyncState, NegotiateStream)
            Console.WriteLine("ImpersonationLevel: {0}", authStream.ImpersonationLevel)

            ' End the asynchronous operation.
            authStream.EndAuthenticateAsClient(ar)

        End Sub

        ' The following method is called when the write operation completes.
        Public Shared Sub EndWriteCallback(ar As IAsyncResult)

            Console.WriteLine("Client ending write operation...")
            Dim authStream = CType(ar.AsyncState, NegotiateStream)

            ' End the asynchronous operation.
            authStream.EndWrite(ar)

        End Sub
    End Class

    ' The following class displays the properties of an AuthenticatedStream.
    Public Class AuthenticatedStreamReporter
        Public Shared Sub DisplayProperties(stream As AuthenticatedStream)
            Console.WriteLine("IsAuthenticated: {0}", stream.IsAuthenticated)
            Console.WriteLine("IsMutuallyAuthenticated: {0}", stream.IsMutuallyAuthenticated)
            Console.WriteLine("IsEncrypted: {0}", stream.IsEncrypted)
            Console.WriteLine("IsSigned: {0}", stream.IsSigned)
            Console.WriteLine("IsServer: {0}", stream.IsServer)
        End Sub
    End Class
End Namespace

O exemplo de código seguinte demonstra o lado servidor de uma ligação cliente-servidor que utiliza o NegotiateStream para autenticar o cliente e ler uma mensagem enviada pelo cliente.

using System;
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Authentication;
using System.Security.Principal;
using System.Text;
using System.IO;
using System.Threading;

namespace Examples.NegotiateStreamExample
{
    public class AsynchronousAuthenticatingTcpListener
    {
        public static void Main()
        {
            // Create an IPv4 TCP/IP socket.
            TcpListener listener = new TcpListener(IPAddress.Any, 11000);
            // Listen for incoming connections.
            listener.Start();
            while (true)
            {
                TcpClient clientRequest;
                // Application blocks while waiting for an incoming connection.
                // Type CNTL-C to terminate the server.
                clientRequest = listener.AcceptTcpClient();
                Console.WriteLine("Client connected.");
                // A client has connected.
                try
                {
                    AuthenticateClient(clientRequest);
                }
                catch (Exception e)
                {
                    Console.WriteLine(e);
                }
            }
        }

        public static void AuthenticateClient(TcpClient clientRequest)
        {
            NetworkStream stream = clientRequest.GetStream();
            // Create the NegotiateStream.
            NegotiateStream authStream = new NegotiateStream(stream, false);
            // Save the current client and NegotiateStream instance
            // in a ClientState object.
            ClientState cState = new ClientState(authStream, clientRequest);
            // Listen for the client authentication request.
            Task authTask = authStream
                .AuthenticateAsServerAsync()
                .ContinueWith(task => { EndAuthenticateCallback(cState); });

            // Any exceptions that occurred during authentication are
            // thrown by the EndAuthenticateAsServer method.
            try
            {
                // This call blocks until the authentication is complete.
                authTask.Wait();
            }
            catch (AuthenticationException e)
            {
                Console.WriteLine(e);
                Console.WriteLine("Authentication failed - closing connection.");
                return;
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                Console.WriteLine("Closing connection.");
                return;
            }

            Task<int> readTask = authStream
                .ReadAsync(cState.Buffer, 0, cState.Buffer.Length);

            readTask
                .ContinueWith((task) => { EndReadCallback(cState, task.Result); })
                .Wait();
            // Finished with the current client.
            authStream.Close();
            clientRequest.Close();
        }

        private static void EndAuthenticateCallback(ClientState cState)
        {
            // Get the saved data.
            NegotiateStream authStream = (NegotiateStream)cState.AuthenticatedStream;
            Console.WriteLine("Ending authentication.");

            // Display properties of the authenticated client.
            IIdentity id = authStream.RemoteIdentity;
            Console.WriteLine("{0} was authenticated using {1}.",
                id.Name,
                id.AuthenticationType
            );
        }

        private static void EndReadCallback(ClientState cState, int bytes)
        {
            NegotiateStream authStream = (NegotiateStream)cState.AuthenticatedStream;
            // Read the client message.
            try
            {
                cState.Message.Append(Encoding.UTF8.GetChars(cState.Buffer, 0, bytes));
                if (bytes != 0)
                {
                    Task<int> readTask = authStream.ReadAsync(cState.Buffer, 0, cState.Buffer.Length);
                    readTask
                        .ContinueWith(task => { EndReadCallback(cState, task.Result); })
                        .Wait();

                    return;
                }
            }
            catch (Exception e)
            {
                // A real application should do something
                // useful here, such as logging the failure.
                Console.WriteLine("Client message exception:");
                Console.WriteLine(e);
                return;
            }
            IIdentity id = authStream.RemoteIdentity;
            Console.WriteLine("{0} says {1}", id.Name, cState.Message.ToString());
        }
    }
    // ClientState is the AsyncState object.
    internal class ClientState
    {
        private StringBuilder _message = null;

        internal ClientState(AuthenticatedStream a, TcpClient theClient)
        {
            AuthenticatedStream = a;
            Client = theClient;
        }
        internal TcpClient Client { get; }

        internal AuthenticatedStream AuthenticatedStream { get; }

        internal byte[] Buffer { get; } = new byte[2048];

        internal StringBuilder Message
        {
            get { return _message ??= new StringBuilder(); }
        }
    }
}

Observações

Use a NegotiateStream classe para autenticação e para ajudar a proteger a informação transmitida entre um cliente e um servidor. Usando NegotiateStream, pode fazer o seguinte.

• Envie as credenciais do cliente para o servidor para Suplantação ou Delegação.
• Solicitar autenticação do servidor.
• Encripte e/ou assine os dados antes de os transmitir.

A autenticação deve ser realizada antes de transmitir informação. Os clientes solicitam autenticação usando os métodos síncronos AuthenticateAsClient , que bloqueiam até a autenticação ser concluída, ou os métodos assíncronos BeginAuthenticateAsClient , que não bloqueiam enquanto aguardam a conclusão da autenticação. Os servidores solicitam autenticação usando métodos síncronos AuthenticateAsServer ou assíncronos BeginAuthenticateAsServer . O cliente, e opcionalmente o servidor, é autenticado usando o protocolo de segurança Negotiate. O protocolo Kerberos é usado para autenticação se tanto o cliente como o servidor o suportarem; caso contrário, é usado NTLM. A NegotiateStream classe realiza a autenticação usando a Interface de Suporte de Segurança (SSPI).

Quando a autenticação for bem-sucedida, deve verificar as propriedades e IsEncryptedIsSigned para determinar que serviços de segurança serão utilizados NegotiateStream para ajudar a proteger os seus dados durante a transmissão. Verifique a IsMutuallyAuthenticated propriedade para determinar se ocorreu autenticação mútua. Pode obter informações sobre o cliente ou servidor remoto que utiliza a RemoteIdentity propriedade.

Se a autenticação falhar, receberá um AuthenticationException ou um InvalidCredentialException. Neste caso, pode tentar a autenticação novamente com uma credencial diferente.

Envia dados usando métodos síncronos Write ou assíncronos WriteAsyncBeginWrite. Recebes dados usando métodos síncronos Read ou assíncronos BeginReadReadAsync. Se serviços de segurança como encriptação ou assinatura estiverem ativados, estes são automaticamente aplicados aos seus dados pelo NegotiateStream.

O NegotiateStream transmite dados usando um fluxo que fornece ao criar o NegotiateStream. Quando fornece este fluxo subjacente, tem a opção de especificar se fechar o NegotiateStream fluxo também fecha o fluxo subjacente.

Ver também

• Alterações à autenticação NTLM para HTTPWebRequest na Versão 3.5 SP1