Spring websocket message broker adding extra Access-Control-Allow-Origin header to respose - spring-boot

Question

I have an application that includes a Spring cloud gateway that sits in front of an app which (among other things) supports web socket connections (sockJS). The gateway does a simple url rewrite when it forwards to the app. The two are currently running Spring-Boot 2.0.5.RELEASE and Spring-Cloud Finchley.RELEASE. According to the source I pulled down, this should be using spring-websockets-5.0.9.
When I try to upgrade to 2.1.2.RELEASE and Greenwich.RELEASE for Spring-Boot and Spring-Cloud respectively, my websocket connections start failing because an extra Access-Cloud-Allow-Origin is being injected into the response.
My gateway has a simple CORS filter like this (the values are constants and not relevant):
#Bean
public WebFilter corsFilter() {
return (ServerWebExchange ctx, WebFilterChain chain) -> {
Mono<Void> result;
ServerHttpRequest request = ctx.getRequest();
if (CorsUtils.isCorsRequest(request)) {
ServerHttpResponse response = ctx.getResponse();
HttpHeaders headers = response.getHeaders();
headers.add("Access-Control-Allow-Origin", ALLOWED_ORIGIN);
headers.add("Access-Control-Allow-Methods", ALLOWED_METHODS);
headers.add("Access-Control-Max-Age", MAX_AGE);
headers.add("Access-Control-Allow-Headers",ALLOWED_HEADERS);
if (request.getMethod() == HttpMethod.OPTIONS) {
response.setStatusCode(HttpStatus.OK);
result = Mono.empty();
} else {
result = chain.filter(ctx);
}
} else {
result = chain.filter(ctx);
}
return result;
};
}
And my web socket config on the downstream app is simply this:
#Configuration
#EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {
#Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker("/topic");
config.setApplicationDestinationPrefixes("/app");
}
#Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/ws")
.setAllowedOrigins("*")
.withSockJS();
}
}
If I comment out the .setAllowedOrigins("*") in the registerStompEndpoints method, I correctly get 403 access denied responses, and the response only has the Access-Control-Allow-Origin header as injected by the gateway.
With the method in place as shown here, the websocket response completes as expected with a success response to the caller, but the response header contains both the access control header injected by the gateway plus another Access-Control-Allow-Origin header which is set to the value of the caller (in my case, http://localhost:4200 for the front-end application.) None of the other access control headers are duplicated.
How can I configure the Spring websocket message broker to not inject the Access-Control-Allow-Origin header? This was working, and still works if I roll back to 2.0.5/Finchley.

Answer 1

I faced this issue recently and I was able to resolve it by calling setSupressCors method. The documentation says that
This option can be used to disable automatic addition of CORS headers for SockJS requests.
Here is a code sample:
#Configuration
#EnableWebSocketMessageBroker
public class WebsocketMessageBrokerConfig implements WebSocketMessageBrokerConfigurer {
#Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/websocket/handshake")
.setAllowedOrigins("*")
.withSockJS()
.setSupressCors(true);
}
}