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

Genius idea. In all my tests I hadn't thought of setting the response code in the predicate and then letting it continue to the servlet and caching it there. I just tested this and it does appear to work well. I added this outer handler chain wrapper to my deployment info deploymentInfo.addOuterHandlerChainWrapper(next -> new HttpHandler() { @Override public void handleRequest(HttpServerExchange exchange) throws Exception { if( exchange.getStatusCode() > 399 && exchange.getResponseContentLength() == -1 ) { ServletRequestContext src = exchange.getAttachment(ServletRequestContext.ATTACHMENT_KEY); ((HttpServletResponse)src.getServletResponse()).sendError(exchange.getStatusCode()); } else { next.handleRequest(exchange); } } }); (I don't know if the exchange.getResponseContentLength() check is needed or the best way to do that) And then I registered a custom handler I called *send-error-page* that has this handleRequest method: public void handleRequest(final HttpServerExchange exchange) throws Exception { exchange.setStatusCode(responseCode); next.handleRequest(exchange); } Then this predicate rule path(/box.json)->send-error-page(404) serves up my servlet's custom error page for that request. 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 Tue, Jul 7, 2020 at 6:39 PM Stuart Douglas <sdouglas(a)redhat.com&gt; wrote: > 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 >>>>>>> >>>>>>>