Taylohtio/GeneralApi/GeneralApi.WcfService/Pox/CustomWebHttpErrorHandler.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Dispatcher;
using System.ServiceModel.Web;
using System.Text;
using WcfRestContrib.ServiceModel.Channels;
using WcfRestContrib.ServiceModel.Description;
using WcfRestContrib.ServiceModel.Dispatcher;
using WcfRestContrib.ServiceModel.Web;
using WebException = WcfRestContrib.ServiceModel.Web.Exceptions.WebException;

namespace Taloyhtio.GeneralApi.WcfService
{
    // Custom error handler shows error message instead of generic Internal Server Error.
    // NOTE: this error handler doesn't help when exception occurs in http module (e.g. UnitOfWork).
    // In this case generic Internal Server Error is shown
    public class CustomWebHttpErrorHandler : IErrorHandler
    {
//        [DataContract(Name = "Error", Namespace = "")]
//        private class WebExceptionContract : IWebExceptionDataContract
//        {
//            public void Init(WebException exception)
//            {
//                this.Message = exception.Message;
//                this.Status = (int)exception.Status;
//            }
//
            // Properties
//            [DataMember(Name = "Message")]
//            public string Message { get; set; }
//            [DataMember(Name = "Status")]
//            public int Status { get; set; }
//        }

        bool IErrorHandler.HandleError(Exception error)
        {
            return true;
        }

        // Wraps all exceptions thrown in the service in common wrapper (FaultException<CustomFaultException>)
        // so clients will be able to get exception details
        /*void IErrorHandler.ProvideFault(Exception error, MessageVersion version, ref Message fault)
        {
            string errorMsg = error != null ? error.Message : "";

            var faultException = new FaultException<CustomFaultException>(
                new CustomFaultException{Reason = errorMsg});

            var msgFault = faultException.CreateMessageFault();

            fault = Message.CreateMessage(version, msgFault, faultException.Action);

            var statusCode = HttpStatusCode.InternalServerError;
            if (error is WebException)
            {
                statusCode = ((WebException)error).Status;
            }
            var rmp = new HttpResponseMessageProperty {StatusCode = statusCode};
            fault.Properties.Add(HttpResponseMessageProperty.Name, rmp);
        }*/

        void IErrorHandler.ProvideFault(Exception error, MessageVersion version, ref Message fault)
        {
            var statusCode = HttpStatusCode.InternalServerError;
            // 2011-06-12: although it is real REST to provide StatusCode, it is not easy to do
            // with json endpoints because WebScriptEnablingBehavior is sealed and we can't do the same
            // thing for it. So for consistentcy I disabled it for pox as well
//            if (error is WebException)
//            {
//                statusCode = ((WebException) error).Status;
//            }

            string errorMsg = error != null ? error.Message : "";

            //string body = ErrorBodyWriter.GetBody(statusCode, error.Message);
            fault = Message.CreateMessage(version, null, 
                new ErrorBodyWriter {Code = statusCode, Message = errorMsg});
            
            var rmp = new HttpResponseMessageProperty();
            
            rmp.StatusCode = statusCode;
            
            // 2011-06-12: if we use custom status description it will causes "protocol violation" error
            // use body as description. On client side WCF will use this property for exception.Message
            //rmp.StatusDescription = string.Format("{0}: {1}", statusCode, error.Message);

            // convert error msg to base64 and store it in custom header. Client will read it via custom message inspector
            if (!string.IsNullOrEmpty(errorMsg))
            {
                rmp.Headers[Common.Constants.HttpHeaders.Error] = Convert.ToBase64String(Encoding.UTF8.GetBytes(errorMsg));
            }
            fault.Properties.Add(HttpResponseMessageProperty.Name, rmp);
        }

        /*void IErrorHandler.ProvideFault(Exception error, MessageVersion version, ref System.ServiceModel.Channels.Message fault)
        {
            WebException webException;
            WebErrorHandlerConfigurationBehavior behavior;
            if (error != null)
            {
                if (error is WebException)
                {
                    webException = (WebException) error;
                }
                else
                {
                    //                string unhandledErrorMessage;
                    //                behavior = GetWebErrorHandlerConfiguration();
                    //                if (behavior.ReturnRawException)
                    //                {
                    //                    unhandledErrorMessage = error.ToString();
                    //                }
                    //                else
                    //                {
                    //                    unhandledErrorMessage = ((behavior != null) && (behavior.UnhandledErrorMessage != null)) ? behavior.UnhandledErrorMessage : "An error has occured processing your request.";
                    //                }
                    webException = new WebException(error, HttpStatusCode.InternalServerError, error.Message,
                                                    new object[0]);
                }
            }
            else
            {
                webException = new WebException(HttpStatusCode.InternalServerError, "An error has occured processing request.");
            }
            webException.UpdateHeaders(WebOperationContext.Current.OutgoingResponse.Headers);
            WebOperationContext.Current.OutgoingResponse.StatusCode = webException.Status;
            WebOperationContext.Current.OutgoingResponse.StatusDescription = webException.Status.ToString();
            WebDispatchFormatter webDispatchFormatter = null;
            if (OperationContext.Current.OutgoingMessageProperties.ContainsKey("WebDispatcherFormatter"))
            {
                webDispatchFormatter = OperationContext.Current.OutgoingMessageProperties["WebDispatcherFormatter"] as WebDispatchFormatter;
            }
            if (webDispatchFormatter != null)
            {
                IWebExceptionDataContract exceptionContract = new WebExceptionContract();
//                behavior = GetWebErrorHandlerConfiguration();
//                if ((behavior != null) && behavior.HasExceptionDataContract)
//                {
//                    exceptionContract = behavior.CreateExceptionDataContract();
//                }
//                else
//                {
//                    exceptionContract = new WebExceptionContract();
//                }
                exceptionContract.Init(webException);
                fault = webDispatchFormatter.Serialize(exceptionContract, typeof(WebExceptionContract), WebOperationContext.Current.IncomingRequest.GetAcceptTypes());
            }
            else
            {
                WebOperationContext.Current.OutgoingResponse.ContentType = "text/html";
                fault = Message.CreateMessage(MessageVersion.None, (string)null, (BodyWriter)new BinaryBodyWriter(GenerateResponseText(webException.Message)));
                fault.SetWebContentFormatProperty(WebContentFormat.Raw);
            }
            fault.UpdateHttpProperty();

        }*/

//        private static WebErrorHandlerConfigurationBehavior GetWebErrorHandlerConfiguration()
//        {
//            return OperationContext.Current.Host.Description.FindBehavior<WebErrorHandlerConfigurationBehavior, WebErrorHandlerConfigurationAttribute>(delegate(WebErrorHandlerConfigurationAttribute x)
//            {
//                return x.BaseBehavior;
//            });
//        }

//        private static string GenerateResponseText(string message)
//        {
//            return string.Format("<html><body style=\"font-family:Arial;font-size:11pt;\">{0}</body></html>", message);
//        }
    }



    internal class ErrorBodyWriter : BodyWriter
    {
        public HttpStatusCode Code { get; set; }
        public string Message { get; set; }

        public ErrorBodyWriter()
            : base(true)
        {
        }

        protected override void OnWriteBodyContents(System.Xml.XmlDictionaryWriter writer)
        {
            string errorMsg = GetBody(Code, Message);
            System.Xml.Linq.XElement xElement = System.Xml.Linq.XElement.Load(new System.IO.StringReader(errorMsg));

            xElement.WriteTo(writer);
        }

        public static string GetBody(HttpStatusCode statusCode, string msg)
        {
            string format = "<?xml version=\"1.0\" encoding=\"utf-8\"?>";
            format += "<error>";
            format += "    <code>{0}</code>";
            format += "    <msg>{1}</msg>";
            format += "</error>";

            string errorMsg = string.Format(format, statusCode, msg);
            return errorMsg;
        }
    }
}