How can I use existingResponse="Auto" successfully? - c#

So I am returning detailed 400 error responses from my MVC web app. Setting existingResponse="PassThrough" works, but that's not what I want. I don't want to expose all failures, I only want to expose them when I have custom responses.
Auto, is set by default, but I deliberately set it. However, the documentation says "SetStatus" flag must be set, but I have no idea how to do such a thing. I wrote the following four controller methods in order to test it, and only BadRequestD works. The others set the status code and the status just fine, but the body content is "Bad Request".
public ActionResult BadRequestA()
{
Response.StatusCode = 400;
return Content("weeeeee");
}
public ActionResult BadRequestB()
{
Response.Status = "400 U DUN MESSED UP";
return Content("weeeeee");
}
public ActionResult BadRequestC()
{
Response.Status = "400 U DUN MESSED UP";
Response.StatusCode = 400;
return Content("weeeeee");
}
public ActionResult BadRequestD()
{
Response.StatusCode = 400;
Response.TrySkipIisCustomErrors = true;
return Content("weeeeee");
}

However, the documentation says "SetStatus" flag must be set, but I have no idea how to do such a thing
It's actually talking about the fTrySkipCustomErrors flag/argument to the IHttpResponse::SetStatus method in the IIS C++ SDK (see note I added to bottom of documentation here). But in ASP.NET the flag is exposed as Response.TrySkipIisCustomErrors. So according to:
http://www.iis.net/configreference/system.webserver/httperrors
Auto = Leaves the response untouched only if the SetStatus flag is set
I would expect to see IIS replace the response with its own html error page content (you can configure what that content is) by default unless you set:
Response.TrySkipIisCustomErrors = true;
Which is what you're seeing.
Additional related info, in MVC5 it seems to act as if that flag is true even if it's false for uncaught exceptions which I don't see in WebForms. As a workaround in Global.asax I'm:
protected void Application_Error()
{
var error = Server.GetLastError();
Server.ClearError();
//code to log error here
var httpException = error as HttpException;
Response.StatusCode = httpException != null ? httpException.GetHttpCode() : (int)HttpStatusCode.InternalServerError;
}

If you need to have custom responses with 4xx http statuses and still want to use Custom Error Pages here's what you should do:
set existingResponse="Auto" in web.config;
set TrySkipIisCustomErrors = true in your action (one that returns 4xx status and a content);
clear server error in global.asax (in Application_Error() - Server.ClearError()) and re-set the status code (Reponse.StatusCode = ((HttpException)Server.GetLastError()).GetHttpCode())
It's weird that IIS team didn't implement existingResponse attribute for specific status codes, so it's impossible to use existingResponse="PassThrough" just for one (or few) codes.

Related

Adding the WWW-Authenticate header gives an error

I'm trying to configure basic access authorization on my .NET HttpListener but I keep running into the same error. I've tried all the solutions that can be found on this site and many others but with no success.
I need to use admin/admin as username/password for basic authentication. The wikipedi page shows how the header should look, which I followed.
I keep getting the error "The header WWW-Authenticate must be changed with the correct method, parameter:name" there is however no parameter called "name" that must be added, like shown on the wikipedia page. I've ran out of options unfortunately and hope that somebody can help.
My code is as follows
private void WebRequestCallback(IAsyncResult result)
{
if (httpListener == null)
{
return;
}
HttpListenerContext context = httpListener.EndGetContext(result);
if (basicAccessAuth)
{
HttpListenerRequest Request = context.Request;
HttpListenerResponse Response = context.Response;
httpListener.AuthenticationSchemes = AuthenticationSchemes.Basic;
NameValueCollection nvCol = new NameValueCollection();
nvCol.Add("Authorization", "admin:admin");
httpListener.Realm = "Overflow";
Request.Headers.Add(nvCol); // error gets thrown here, missing "name" parameter
Response.Headers.Add("WWW-Authenticate: Basic YWRtaW46YWRtaW4=");
HttpListenerBasicIdentity identity = (HttpListenerBasicIdentity)context.User.Identity;
MessageBox.Show(identity.Name);
}
httpListener.BeginGetContext(new AsyncCallback(WebRequestCallback), httpListener);
if (ReceiveWebRequest != null)
{
ReceiveWebRequest(context);
}
ProcessRequest(context);
}
I have managed to figure out my issue. I added the header in the wrong way, it should be Response.AddHeader instead of Response.Headers.Add

How to create a custom HTTP status code between 110 - 150 in action result?

I want to add a custom error code like 110, 108 with some message like "Invalid Id". Please suggest how to break the default HTTP status code in ASP.NET
Firstly you can't use 1xx range of HTTP status codes to show error.
1xx Informational
2xx Success
3xx Redirection
4xx Client Error
5xx Server Error
You can learn more about HTTP status codes here as well.
Secondly as you want to create custom code, I think this will answer your question How to show the status code with custom message in c#?
For example :
public ActionResult TestError(string id) // id = error code
{
Response.StatusCode = 400; // Replace .AddHeader
var error = new Error(); // Create class Error() w/ prop
error.ErrorID = 123;
error.Level = 2;
error.Message = "You broke the Internet!";
return Json(error, JsonRequestBehavior.AllowGet);
}

Flurl Client - Is it possible to access the headers from a failed request?

I am using Flurl Client to call a restful API with a post data. There is a validation performed on the server on the data I submit and it returns back a header containing an error message for the user.
As the request requirement doesn't satisfy server marks the request as 400 BadRequest. In the below code on line cli.Request(uri).PostJsonAsync(data) it throws the FlurlHttpException with appropriate status code.
Now, as there is a problem with the input data by the user I want to report the user back with the error message which I receive from the server in the header. However, I am unable to access the response headers as the request has failed.
Is there any other way to access the response headers from a failed request using Flurl?
try
{
using (var cli = new FlurlClient(baseUrl))
{
var httpResponse = await cli.Request(uri).PostJsonAsync(data);
var errorMessage = httpResponse.GetHeaderValue("errorMessage");
}
}
catch (FlurlHttpException ex)
{
}
Using an event handler works, but I think those are better for cross-cutting concerns like logging that you don't want cluttering the main flow of your app. You basically want to allow and/or handle 400 responses as part of that main flow. You can do that more directly with AllowHtttpStatus, which can be set on the client:
cli.AllowHtttpStatus(HttpStatusCode.BadRequest);
or the request:
var httpResponse = await cli
.Request(uri)
.AllowHttpStatus(HttpStatusCode.BadRequest)
.PostJsonAsync(data);
Either way, the call will not throw on a 400.
Another way to do this, and one I'd recommend if your app logic takes a completely different path on an error condition than on a success condition, is to keep your try/catch in place and use the Response property of the exception to handle the error condition:
try
{
await cli.Request(uri).PostJsonAsync(data);
// handle success condition
}
catch (FlurlHttpException ex) when (ex.Response?.StatusCode == 400)
{
var errorMessage = ex.Response.GetHeaderValue("errorMessage");
// handle error condition
}
As a side note, there are some significant changes coming in 3.0 that you should be aware of as they touch on some of these areas directly:
https://github.com/tmenier/Flurl/issues/354
https://github.com/tmenier/Flurl/issues/488
I am configuring the Error Event Handler to report any error. As a result, the code doesn't jump to the exception block it asynchronously fires the event handler, and the rest of my subsequent code executes OK with an appropriate httpResponseMessage, StatusCode, headers everything.
...
FlurlHttp.Configure(settings => settings.OnErrorAsync = HandleFlurlErrorAsync);
using (var cli = new FlurlClient(baseUrl))
{
var httpResponse = await cli.Request(uri).PostJsonAsync(data);
var errorMessage = httpResponse.GetHeaderValue("errorMessage");
}
...
private async Task HandleFlurlErrorAsync(HttpCall call)
{
//Log your exception here
call.ExceptionHandled = true;
}

Web API 2 return an error and make http.post catch it

Up to now if a web api 2 error happened and I caught it, I'd return a custom object and fill in the error message from the catch. This would however make the actually http.post() go into success method instead of the error and then I'd have to look at my own boolean success variable and if true all good, if false show error. This is kind of annoying as I have to look for errors in 2 different places for 2 different reasons. From Web API 2 is there a way I can make the http.post() trigger the error callback while I fill out the error message if I catch an error in the web api controller?
[HttpPost]
public MyResponseObject UpdateData(RequestObject req)
{
MyResponseObject resp = new MyResponseObject();
resp.Success = true;
try{
// error happens here
}catch(Exception ex){
resp.Success = false;
resp.Msg = ex.Message;
}
return resp;
}
The http.post() call will still be successful but now I have to look in the success callback for my resp.Success to see if it was REALLY successful or not. Sure the API call was able to be made, but something went wrong inside of it. I'd like to just be able to display that message and fail the call so the http.post() error callback is called with the exception message.
Just throw an exception:
throw new HttpResponseException(HttpStatusCode.InternalServerError);
If you want to customize the response that is returned you can create a HttpResponseMessage with more detail:
var response = new HttpResponseMessage(HttpStatusCode.InternalServerError)
{
Content = new StringContent("We messed up"),
ReasonPhrase = "Error"
}
throw new HttpResponseException(resp);
Documentation here

Issuing HEAD request with IRestClient in ServiceStack

The context: I've built a REST service which handles 'Profile' objects. Each profile is required to have a unique name. One of the operations that clients will need to do for validation purposes is check to make sure that a profile with the given name does not already exist.
Rather than build a RPC-style 'ProfileExists' method, I would prefer to stay within REST design principles and issue a HEAD request to the Profile with the given name and then return the appropriate response code depending on whether the profile already exists or not (200, 404, respectively), no response body needed.
Following the conventions with the newer ServiceStack API, I've set up a method to accept Head requests and tested it successfully for both cases using Fiddler:
public object Head(GetProfile request)
{
ValidateRequest(request);
HttpStatusCode responseCode;
using (var scope = new UnitOfWorkScope())
{
responseCode = _profileService.ProfileExists(request.Name) ? HttpStatusCode.OK : HttpStatusCode.NotFound;
scope.Commit();
}
return new HttpResult { StatusCode = responseCode };
}
The trouble is on the client-side. Issuing the HEAD request through ServiceStack's IRestClient interface is proving difficult. While there are methods for Get, Post, Put, and Delete, there is no method for Head. From there I assumed I could use CustomMethod to specify the HEAD verb explicitly as a parameter:
public bool ProfileExists(string profileName)
{
try
{
var response = _restClient.CustomMethod<IHttpResult>(HttpMethods.Head, new GetProfile { Name = profileName });
return response.StatusCode == HttpStatusCode.OK;
}
catch (WebServiceException ex)
{
if (ex.StatusCode == 404)
return false;
}
// Return false for any other reason right now.
return false;
}
However, the underlying implementation (ServiceClientBase) throws an exception when validating the HttpVerb parameter:
if (HttpMethods.AllVerbs.Contains(httpVerb.ToUpper()))
throw new NotSupportedException("Unknown HTTP Method is not supported: " + httpVerb);
The set HttpMethods.AllVerbs contains all of the usual verbs for RFC 2616 and more. Unless this behavior is a bug, throwing an exception for any of the known HTTP verbs suggests that the author's intent for CustomMethod did not include being able to issue requests for a known HTTP verb.
Which leads me to my question: How do I issue a HEAD request on the client side in ServiceStack?
This was a bug:
if (HttpMethods.AllVerbs.Contains(httpVerb.ToUpper()))
throw new NotSupportedException("Unknown HTTP Method is not supported: " + httpVerb);
That I've just fixed in this commit. This fix will be available on the next release of ServiceStack (v3.9.33+) due this weekend.

Categories

Resources