Properly Implementing IAuthorizationFilter in Web API

Question

I'm having trouble figuring out how to implement an authorization filter in Web API using IAuthorizationFilter from System.Web.Http.Filters.

This is a simple filter I wrote to respond to all non-https requests with a 403 forbidden response:

public class HttpsFilter : IAuthorizationFilter {
    public bool AllowMultiple {
        get {
            return false;
        }
    }

    public Task<HttpResponseMessage> ExecuteAuthorizationFilterAsync( HttpActionContext actionContext, CancellationToken cancellationToken, Func<Task<HttpResponseMessage>> continuation ) {
        var request = actionContext.Request;

        if ( request.RequestUri.Scheme != Uri.UriSchemeHttps ) {
            HttpResponseMessage response = request.CreateResponse( HttpStatusCode.Forbidden );
            response.Content = new StringContent( "<h1>HTTPS Required</h1>", Encoding.UTF8, "text/html" );
            actionContext.Response = response;

            return new Task<HttpResponseMessage>( delegate() {
                return response;
            } );
        }
        else
            return continuation();
    }
}

What I have written so far runs, but when I try to access the api over regular http, it just hangs and I never get a response.

Answer 1

You either need to save the task into a variable and call the task.Start() method before returning it, or use the Task<HttpResponseMessage>.Factory.StartNew(Action action) method to create the task.