Question

我有一个会话WCF双工服务（绑定：NetTcpBinding）：此服务具有启动会话的Subscribe方法，以及终止会话的Unsubscribe方法。该服务保留了一个黑名单端点，因此我希望该服务拒绝访问此黑名单中包含的端点。有没有办法自动过滤来自某些地址的连接，避免创建新会话？

Answer 1

每当启动新会话时，都会在WCF服务中初始化新的实例上下文，因此您可以使用自定义IInstanceContextInitializer实现来执行该验证。下面的代码显示了如何实现这一目标的一种方式。

public class StackOverflow_12089879
{
    [ServiceContract(SessionMode = SessionMode.Required)]
    public interface IStackCalculator
    {
        [OperationContract]
        void Enter(double value);
        [OperationContract]
        double Add();
        [OperationContract]
        double Subtract();
        [OperationContract]
        double Multiply();
        [OperationContract]
        double Divide();
    }
    public class StackCalculator : IStackCalculator
    {
        public Stack<double> stack = new Stack<double>();

        public void Enter(double value)
        {
            Console.WriteLine("Entering {0}", value);
            stack.Push(value);
        }

        public double Add()
        {
            return Execute("Add", (x, y) => x + y);
        }

        public double Subtract()
        {
            return Execute("Subtract", (x, y) => x - y);
        }

        public double Multiply()
        {
            return Execute("Multiply", (x, y) => x * y);
        }

        public double Divide()
        {
            return Execute("Divide", (x, y) => x / y);
        }

        private double Execute(string operationName, Func<double, double, double> operation)
        {
            double first = stack.Pop();
            double second = stack.Pop();
            double result = operation(first, second);
            Console.WriteLine("Executing {0}({1}, {2}), result = {3}", operationName, first, second, result);
            stack.Push(result);
            return result;
        }
    }
    static Binding GetBinding()
    {
        var result = new NetTcpBinding(SecurityMode.None);
        return result;
    }
    public class MyInstanceContextInitializer : IEndpointBehavior, IInstanceContextInitializer
    {
        public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
        {
        }

        public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
        {
        }

        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
        {
            endpointDispatcher.DispatchRuntime.InstanceContextInitializers.Add(this);
        }

        public void Validate(ServiceEndpoint endpoint)
        {
        }

        public void Initialize(InstanceContext instanceContext, Message message)
        {
            RemoteEndpointMessageProperty remp = (RemoteEndpointMessageProperty)message.Properties[RemoteEndpointMessageProperty.Name];
            Console.WriteLine("Starting new session from {0}:{1}", remp.Address, remp.Port);
            Console.WriteLine("If session should not be started, throw an exception here");
        }
    }
    public static void Test()
    {
        string baseAddress = "net.tcp://" + Environment.MachineName + ":8000/Service";
        ServiceHost host = new ServiceHost(typeof(StackCalculator), new Uri(baseAddress));
        ServiceEndpoint endpoint = host.AddServiceEndpoint(typeof(IStackCalculator), GetBinding(), "");
        endpoint.Behaviors.Add(new MyInstanceContextInitializer());
        host.Open();
        Console.WriteLine("Host opened");

        ChannelFactory<IStackCalculator> factory = new ChannelFactory<IStackCalculator>(GetBinding(), new EndpointAddress(baseAddress));
        IStackCalculator proxy = factory.CreateChannel();
        proxy.Enter(40);
        proxy.Enter(30);
        proxy.Enter(20);
        proxy.Add();
        proxy.Subtract();

        ChannelFactory<IStackCalculator> factory2 = new ChannelFactory<IStackCalculator>(GetBinding(), new EndpointAddress(baseAddress));
        IStackCalculator proxy2 = factory.CreateChannel();
        proxy2.Enter(40);
        proxy2.Enter(30);
        proxy2.Enter(20);
        proxy2.Add();
        proxy2.Subtract();

        ((IClientChannel)proxy).Close();
        factory.Close();
        ((IClientChannel)proxy2).Close();
        factory2.Close();

        Console.Write("Press ENTER to close the host");
        Console.ReadLine();
        host.Close();
    }
}

如何阻止来自特定地址的传入连接？

1 个答案: