Re: [undertow-dev] response-code handler bypasses configured error pages

Basically I think the only way you can solve this is to attach the error code to the exchange somehow, then have a handler that reads the error code and calls sendError later.Basically write a new response-code handler that sets the code then calls the next handler (so the request gets to Servlet), then add a handler to the Servlet deployment that calls sendError if the exchange status code is > 400. We could actually add this to Undertow very simply, just add a 'continue' param to the response code handler, then always call sendError in servlet if the incoming request response is >400. Can you try this out, and if it works I can look at getting it into Undertow. Stuart On Wed, 8 Jul 2020 at 02:35, Brad Wood <bdw429s(a)gmail.com&gt; wrote: > Stuart, any further suggestions or answers to my outstanding questions? > So far, everything you've suggested doesn't work for various reasons I've > shared here. I also have a number of outstanding questions such as how I > could access the deployment information for the servlet's error pages from > inside an HTTPHandler running in the initial handler chain that fires in > the XNIO worker. > > Thanks! > > ~Brad > > *Developer Advocate* > *Ortus Solutions, Corp * > > E-mail: brad(a)coldbox.org > ColdBox Platform: http://www.coldbox.org > Blog: http://www.codersrevolution.com > > > > On Fri, Jul 3, 2020 at 3:55 PM Brad Wood <bdw429s(a)gmail.com&gt; wrote: > >> After a few hours of experimenting, I was able to answer a few of my own >> questions, but not all of them. >> >> - Yes, it is possible to contribute a custom handler to the >> predicate language-- this is actually pretty sweet. I didn't realize just >> how generic the parser was. >> - In order to get "picked up", the builder class must be listed in >> the >> *META-INF/services/io.undertow.server.handlers.builder.HandlerBuilder* >> file >> - That custom handler suggested by Stuart in the previous message >> ONLY works if the predicate chain is wrapped "inside" the servlet initial >> handler. Otherwise, the servletcontext classes are missing. This >> unfortunately, makes it a no-go for me to be able to use. >> >> The rest of my questions still stand however in so far as how I can >> accomplish what I need. >> >> During my experiments today, I also played with the error-file handler, >> but it also is of no use. Since the response-code handler ends the >> exchange, any error pages declared in the error file handler are never >> used! >> >> error-file( response-codes={404}, >> file="C:\sandbox\predicatetest\custom404.html" ) >> path('/box.json') -> response-code(404) >> >> I even tried creating a custom handler that sets the status code but >> continues the exchange, but then that just serves the original file anyway, >> which causes the error-file handler to do nothing since the response stream >> is already started. >> >> Thanks! >> >> ~Brad >> >> *Developer Advocate* >> *Ortus Solutions, Corp * >> >> E-mail: brad(a)coldbox.org >> ColdBox Platform: http://www.coldbox.org >> Blog: http://www.codersrevolution.com >> >> >> >> On Fri, Jul 3, 2020 at 12:02 PM Brad Wood <bdw429s(a)gmail.com&gt; wrote: >> >>> You probably need to write a custom one that looks like this (plus the >>>> relevant predicate languge bits): >>> >>> >>> Stuart, if I can branch the conversation here back to your idea of a >>> custom handler for a bit... >>> >>> I'm still toying with this, and while the handleRequest() code you have >>> makes perfect sense, I think I'm missing a lot of context on how you were >>> suggesting this would work. >>> >>> - The code you put in your message-- were you suggesting that >>> should be added to the Undertow core as a built in handler or just a custom >>> class I would put in my project? >>> - Would this handler require the predicates be processed downstream >>> of the servlet initial handler in order to work? Because if so, that >>> appears to be a no-go since handlers like the rewrite only appear to work >>> upstream of the servlet >>> - Is it possible to register custom handlers of my own creation >>> with the predicate language or were you suggesting a handler that could >>> only be manually configured? I'm familiar with the handler builder pattern >>> that the built in handlers use, but I'm unclear on how builders get >>> registered with the predicate handler parser. >>> - Actually, I just reviewed the code again now and I see >>> the loadHandlerBuilders() method in the PredicatedhandlersParser class >>> appears to be scanning the classpath for builders. Interesting.... Does >>> Undertow need to be loaded by the same class loader that loaded my custom >>> handlers for this to work? I'm not super familiar with the ServiceLoader >>> stuff >>> - I'm not against building a custom handler that I ship alongside >>> Undertow that provides what I'm looking for, but I'm still interested in >>> having the conversation of how we can improve undertow's core offering. >>> >>> Thanks! >>> >>> ~Brad >>> >>> *Developer Advocate* >>> *Ortus Solutions, Corp * >>> >>> E-mail: brad(a)coldbox.org >>> ColdBox Platform: http://www.coldbox.org >>> Blog: http://www.codersrevolution.com >>> >>> >>> >>> On Thu, Jul 2, 2020 at 7:01 PM Stuart Douglas <sdouglas(a)redhat.com&gt; >>> wrote: >>> >>>> Hmm, this is because the servlet status code is only triggered by a >>>> sendError method, not by just setting the code. >>>> >>>> You probably need to write a custom one that looks like this (plus the >>>> relevant predicate languge bits): >>>> >>>> public class SendErrorHandler implements HttpHandler { >>>> >>>> private final int code; >>>> >>>> public SendErrorHandler(int code) { >>>> this.code = code; >>>> } >>>> >>>> @Override >>>> public void handleRequest(HttpServerExchange exchange) throws >>>> Exception { >>>> ServletRequestContext src = >>>> exchange.getAttachment(ServletRequestContext.ATTACHMENT_KEY); >>>> >>>> ((HttpServletResponse)src.getServletResponse()).sendError(code); >>>> } >>>> } >>>> >>>> Stuart >>>> >>>> >>>> >>>> On Fri, 3 Jul 2020 at 09:40, Brad Wood <bdw429s(a)gmail.com&gt; wrote: >>>> >>>>> Thanks for the reply Stuart. I've tried this with no success, but >>>>> perhaps I'm doing it wrong. >>>>> >>>>> List<PredicatedHandler> ph = >>>>> PredicatedHandlersParser.parse(predicatesLines, _classLoader); >>>>> servletBuilder.addOuterHandlerChainWrapper(next -> >>>>> Handlers.predicates(ph,next)); >>>>> >>>>> When the response-code handler fires, I still get no response body. >>>>> >>>>> On a related note, when I move the predicates into an outer handler >>>>> chain wrapper, my default response listener also doesn't fire at all. >>>>> >>>>> On an unrelated train of thought, I've been trying to see if I can >>>>> get the default response listener to automatically dispatch the correct >>>>> error page, but that hasn't been going well either. If I don't use the >>>>> outer handler chain idea, but try to capture the empty response in a >>>>> default response listener, I can return a static message using the Sender >>>>> class >>>>> >>>>> Sender sender = exchange.getResponseSender(); >>>>> sender.send(errorHTMLString); >>>>> >>>>> But if I try to run something this in my default response listener to >>>>> invoke my error pages >>>>> >>>>> ServletRequestContext src = >>>>> exchange.getAttachment(ServletRequestContext.ATTACHMENT_KEY); >>>>> HttpServletResponseImpl response = src.getOriginalResponse(); >>>>> response.doErrorDispatch( exchange.getStatusCode(), >>>>> exchange.getReasonPhrase() ); >>>>> >>>>> Then it's as though nothing happens and I still get an empty response. >>>>> >>>>> Thanks! >>>>> >>>>> ~Brad >>>>> >>>>> *Developer Advocate* >>>>> *Ortus Solutions, Corp * >>>>> >>>>> E-mail: brad(a)coldbox.org >>>>> ColdBox Platform: http://www.coldbox.org >>>>> Blog: http://www.codersrevolution.com >>>>> >>>>> >>>>> >>>>> On Thu, Jul 2, 2020 at 6:17 PM Stuart Douglas <sdouglas(a)redhat.com&gt; >>>>> wrote: >>>>> >>>>>> The predicate languages are executed before the Servler handlers, so >>>>>> they won't be handled by Servlet error pages. >>>>>> >>>>>> If you are setting this all up programmatically you could use >>>>>> io.undertow.servlet.api.DeploymentInfo#addOuterHandlerChainWrapper to setup >>>>>> the predicate handler after the initial servlet one, which should mean that >>>>>> the servlet error handling will handle the response code. >>>>>> >>>>>> Stuart >>>>>> >>>>>> On Fri, 3 Jul 2020 at 08:25, Brad Wood <bdw429s(a)gmail.com&gt; wrote: >>>>>> >>>>>>> When I configure an error page similar to this: >>>>>>> >>>>>>> servletBuilder.addErrorPage( new ErrorPage( "404.html", 404)); >>>>>>> >>>>>>> This works great when I hit a path in my browser that doesn't >>>>>>> exist. The contents of the *404.html* file is served with a >>>>>>> response code of *404*. >>>>>>> >>>>>>> However, if I also use the predicate language to define something >>>>>>> like: >>>>>>> >>>>>>> path(/box.json)->response-code(404) >>>>>>> >>>>>>> and then I hit *localhost/box.json* in my browser, I get a *404* >>>>>>> status code but with no response body. >>>>>>> >>>>>>> - The docs say the response-code handler ends the exchange, but >>>>>>> should it still respect the error pages? >>>>>>> - How can I modify my use of Undertow to respect the error >>>>>>> pages when using the response-code handler? >>>>>>> - I've seen in the docs the ability to have a >>>>>>> *addDefaultResponseListener()* but I'm not sure if it is the >>>>>>> correct solution for this, nor how I would access the error page >>>>>>> configuration dynamically as to not need to duplicate my work. >>>>>>> >>>>>>> Thanks! >>>>>>> >>>>>>> ~Brad >>>>>>> >>>>>>> *Developer Advocate* >>>>>>> *Ortus Solutions, Corp * >>>>>>> >>>>>>> E-mail: brad(a)coldbox.org >>>>>>> ColdBox Platform: http://www.coldbox.org >>>>>>> Blog: http://www.codersrevolution.com >>>>>>> >>>>>>> _______________________________________________ >>>>>>> undertow-dev mailing list >>>>>>> undertow-dev(a)lists.jboss.org >>>>>>> https://lists.jboss.org/mailman/listinfo/undertow-dev >>>>>> >>>>>>