Question

i need to pass a value from client everytime a request sent to WCF and check that value on server and decide to make the request or not, can any one write an example of that ?im not sure how is that is going be implemented

case:
im generating a key based on the hardware of the client and i want to send that key to the server with every request to check if the key is accepted in the server db and then decide to process the request or not.

thanks in advance.

Answer 1

first we need to implement Behavior and inspector in the client side to send Key to authenticate the client :

 class AuthenticationBehaviour : IEndpointBehavior
{
    #region IEndpointBehavior Members

    public void AddBindingParameters(ServiceEndpoint endpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
    {
    }

    public void ApplyClientBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.ClientRuntime clientRuntime)
    {
        AuthenticationMessageInspector inspector = new AuthenticationMessageInspector();
        clientRuntime.MessageInspectors.Add(inspector);
    }

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.EndpointDispatcher endpointDispatcher)
    {
        //AuthenticationMessageInspector inspector = new AuthenticationMessageInspector();
        //endpointDispatcher.DispatchRuntime.MessageInspectors.Add(inspector);
    }

    public void Validate(ServiceEndpoint endpoint)
    {
    }

    class AuthenticationMessageInspector : IClientMessageInspector
{
    private const string HeaderKey = "Authentication";

    public object BeforeSendRequest(ref Message request, IClientChannel channel)
    {

        if (Session.MachineId == 0)
        {
            Session.MachineId = LicenseGenerator.GenerateLicense();
        }


        request.Headers.Add(MessageHeader.CreateHeader(HeaderKey, string.Empty, Session.MachineId));
        return null;
    }

    public void AfterReceiveReply(ref Message reply, object correlationState)
    {

    }
}

now we need to implement Behavior and inspector in the server side (WCF service) to inspect every request made and extract the header then validate it :

  public class AuthenticationBehaviour : IEndpointBehavior
{
    #region IEndpointBehavior Members

    public void AddBindingParameters(ServiceEndpoint endpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
    {
    }

    public void ApplyClientBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.ClientRuntime clientRuntime)
    {
        //AuthenticationMessageInspector inspector = new AuthenticationMessageInspector();
        //clientRuntime.MessageInspectors.Add(inspector);
    }

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.EndpointDispatcher endpointDispatcher)
    {
        AuthenticationMessageInspector inspector = new AuthenticationMessageInspector();
        endpointDispatcher.DispatchRuntime.MessageInspectors.Add(inspector);
        //Console.WriteLine("Dispatcher Applied!");
    }

    public void Validate(ServiceEndpoint endpoint)
    {
    }

    #endregion
}

   public class AuthenticationMessageInspector : IDispatchMessageInspector

{

    #region Members
    private string conStr = "", commStr = "";
    public IDbConnection Connection { get; set; }
    public IDbCommand Command { get; set; }
    public IDataReader Reader { get; set; }

    #endregion        
    private const string HeaderKey = "Authentication";
    public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
    {
        //Console.WriteLine("recieved Request! ");
        int headerIndex = request.Headers.FindHeader(HeaderKey, string.Empty);
        if (headerIndex < 0 || string.IsNullOrEmpty(request.Headers.GetHeader<String>(headerIndex)))
        {

            throw (new Exception("Access Denied!\n"));
            return null;
        } 


        bool valid = Validate(request.Headers.GetHeader<String>(headerIndex));
        if (!valid)
        {
            Console.WriteLine("recieved Request! From " + request.Headers.GetHeader<String>(headerIndex) + " and Access Denied!\n");
            throw (new Exception("Access Denied!\n" + request.Headers.GetHeader<String>(headerIndex) + " License Number is not athourized! "));         
        }
        if (headerIndex != -1)
        {
            Console.WriteLine("recieved Request! From " + request.Headers.GetHeader<String>(headerIndex));
        }
        return null;

    }

    public void BeforeSendReply(ref Message reply, object correlationState)
    {

    }
}

now lets register the behavior :

            _routingHost.Description.Endpoints[0].Behaviors.Add(new Gateway.Controllers.AuthenticationBehaviour());
_routingHost.Open();

that is it thanks.