c# - How do I restrict access to some methods in WCF?

Question

I am a bit lost getting started with a simple WCF service. I have two methods and I want to expose one to the world and the second one I want to limit to certain users. Eventually I want to be able to use a client application to use the restricted method. So far I can access both methods anonymously:

C# Code

namespace serviceSpace
{
    [ServiceContract]
    interface ILocationService
    {
        [OperationContract]
        string GetLocation(string id);

        [OperationContract]
        string GetHiddenLocation(string id);
    }

    [AspNetCompatibilityRequirements(
     RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    public class LocationService : ILocationService
    {
        [WebGet(UriTemplate = "Location/{id}")]
        public string GetLocation(string id)
        {
            return "O hai, I'm available to everyone.";
        }

        // only use this if authorized somehow
        [WebGet(UriTemplate = "Location/hush/{id}")]
        public string GetHiddenLocation(string id)
        {
            return "O hai, I can only be seen by certain users.";
        }


    }
}

Configuration

<?xml version="1.0"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>    
    <standardEndpoints>
      <webHttpEndpoint>
        <standardEndpoint name="" helpEnabled="true" 
          automaticFormatSelectionEnabled="true"/>
      </webHttpEndpoint>
    </standardEndpoints>
  </system.serviceModel>
</configuration>

How do I get started?

Answer 1

A lot of the answers I found were almost what I needed but not quite right. I wound up setting up ASP.net membership and implementing a custom attribute to pull an authorization header and process login as the request came in. All of the magic happens in BeforeCall and ParseAuthorizationHeader below:

public class UsernamePasswordAuthentication : Attribute, IOperationBehavior, IParameterInspector
{
    public void ApplyDispatchBehavior(OperationDescription operationDescription,
        DispatchOperation dispatchOperation)
    {
        dispatchOperation.ParameterInspectors.Add(this);
    }

    public void AfterCall(string operationName, object[] outputs,
                          object returnValue, object correlationState)
    {
    }

    public object BeforeCall(string operationName, object[] inputs)
    {
        var usernamePasswordString = parseAuthorizationHeader(WebOperationContext.Current.IncomingRequest);
        if (usernamePasswordString != null)
        {
            string[] usernamePasswordArray = usernamePasswordString.Split(new char[] { ':' });
            string username = usernamePasswordArray[0];
            string password = usernamePasswordArray[1];
            if ((username != null) && (password != null) && (Membership.ValidateUser(username, password)))
            {
                Thread.CurrentPrincipal = new GenericPrincipal(new GenericIdentity(username), new string[0]);
                return null;
            }
        }

        // if we made it here the user is not authorized
        WebOperationContext.Current.OutgoingResponse.StatusCode =
            HttpStatusCode.Unauthorized;
        throw new WebFaultException<string>("Unauthorized", HttpStatusCode.Unauthorized);            
    }

    private string parseAuthorizationHeader(IncomingWebRequestContext request)
    {
        string rtnString = null;
        string authHeader = request.Headers["Authorization"];
        if (authHeader != null)
        {
            var authStr = authHeader.Trim();
            if (authStr.IndexOf("Basic", 0) == 0)
            {
                string encodedCredentials = authStr.Substring(6);
                byte[] decodedBytes = Convert.FromBase64String(encodedCredentials);
                rtnString = new ASCIIEncoding().GetString(decodedBytes);
            }
        }
        return rtnString;
    }

    public void AddBindingParameters(OperationDescription operationDescription, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
    {
    }

    public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation)
    {
    }

    public void Validate(OperationDescription operationDescription)
    {
    }

}

From there I just need to add my new attribute to the service contract entries. Any request to that method will require a valid authorization header or a Not Authorized response will be sent back with doing any further processing.

[ServiceContract]
interface ILocationService
{
    [OperationContract]
    string GetLocation(string id);

    [OperationContract]
    [UsernamePasswordAuthentication]  // this attribute will force authentication
    string GetHiddenLocation(string id);
}