implicit cast failed on reactive.TomcatHttpHandlerAdapter$TomcatServerHttpRequest

[tutufool]

When upgrade to spring boot 2.1.1, the newly introduced spring-web-5.1.3.RELEASE gives me exceptions:

 java.lang.IllegalArgumentException: Can not set org.apache.catalina.connector.Request field org.apache.catalina.connector.RequestFacade.request to org.apache.catalina.core.ApplicationHttpRequest
 	at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167) ~[na:1.8.0_20]
 	at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171) ~[na:1.8.0_20]
 	at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58) ~[na:1.8.0_20]
 	at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36) ~[na:1.8.0_20]
 	at java.lang.reflect.Field.get(Field.java:387) ~[na:1.8.0_20]
 	at org.springframework.util.ReflectionUtils.getField(ReflectionUtils.java:169) ~[spring-core-5.1.3.RELEASE.jar:5.1.3.RELEASE]
 	at org.springframework.http.server.reactive.TomcatHttpHandlerAdapter$TomcatServerHttpRequest.createTomcatHttpHeaders(TomcatHttpHandlerAdapter.java:106) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
 	at org.springframework.http.server.reactive.TomcatHttpHandlerAdapter$TomcatServerHttpRequest.<init>(TomcatHttpHandlerAdapter.java:99) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
 	at org.springframework.http.server.reactive.TomcatHttpHandlerAdapter.createRequest(TomcatHttpHandlerAdapter.java:68) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
 	at org.springframework.http.server.reactive.ServletHttpHandlerAdapter.service(ServletHttpHandlerAdapter.java:171) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
 	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.13.jar:9.0.13]
 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
 	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
 	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
 	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:384) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
 	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312) ~[tomcat-embed-core-9.0.13.jar:9.0.13]

related code:

private static HttpHeaders createTomcatHttpHeaders(HttpServletRequest request) {
	org.apache.catalina.connector.Request connectorRequest = (org.apache.catalina.connector.Request)
		ReflectionUtils.getField(COYOTE_REQUEST_FIELD, request);
	Assert.state(connectorRequest != null, "No Tomcat connector request");
	Request tomcatRequest = connectorRequest.getCoyoteRequest();
	TomcatHeadersAdapter headers = new TomcatHeadersAdapter(tomcatRequest.getMimeHeaders());
	return new HttpHeaders(headers);
}

The code assuming pass in request is an org.apache.catalina.connector.RequestFacade.
But actually it's org.apache.catalina.core.ApplicationHttpRequest.

[bclozel]

This is likely to be a bug in Spring Framework.
Could you provide more information on how to reproduce that? Do you have a sample application I can run?

[tutufool]

Here you go:
https://github.com/tutufool/ServletOnReactive

[bclozel]

Thanks for the repro.
I see you're trying to use org.apache.tomcat.websocket.server.WsFilter in your application. I've got a couple of comments about that first:

• For websocket support, you should use what's provided by Spring WebFlux already
• In my opinion, it's a bad idea to use Servlet filters on a WebFlux application. Since WebFlux is using the Tomcat container in async IO mode (note: not just async), nothing should read or write to the request/response in a blocking way. Most filters out there won't work.

With that in mind, there might be a problem still in Spring Framework since we shouldn't maybe enforce the total absence of Servlet Filters. Let me get back to you on that.

[tutufool]

I didn't specify org.apache.tomcat.websocket.server.WsFilter by my own, not sure which component/starter bring it in.

My application contains 2 parts:

1. biz logic served via webflux: RestControllers + WebFilters
2. legacy servlet based admin console: pure servlet + it's own servlet filters

They're both in the same tomcat container, but will not interfere with each other.

[poutsma]

I've created a JIRA for Spring Framework here: https://jira.spring.io/browse/SPR-17611

[poutsma]

Fixed in spring-projects/spring-framework@5e4a896

[wilkinsona]

Thanks, @poutsma. We're building against Framework 5.1.4 snapshots now (as part of #15493) so there's nothing more to do here on the Boot side.

[bclozel]

Thanks @poutsma !

@tutufool the WsFilter seems to be deployed anyway in your arrangement. Even though this issue is fixed on the Framework side, my warning still stands. Servlet async I/O is a very different beast, and mixing blocking + non-blocking IO through filters in the same request/response processing is likely to cause issues.

[tutufool]

@bclozel Thanks for your reminding.

Is there a way to explicitly exclude WsFilter in my case?
I guess WsFilter is default enabled for reactive mode.

However, like I said, my case is special, I have to support both case within same tomcat container:

1. biz logic served via webflux: RestControllers + WebFilters (non-blocking)

2. legacy servlet based admin console: pure servlet + it's own servlet filters (blocking)

1 and 2 are different request/response processing.