Earlier processing of forwarded headers

Forwarded headers are now processed before ServerWebExchange is created
through ForwardedHeaderTransformer which has the same logic as the
ForwardedHeaderFilter but works on the request only.

ForwardedHeaderFilter is deprecated as of 5.1 but if registered it is
removed from the list of filters and ForwardedHeaderTransformer is used
instead.

Issue: SPR-17072

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestMappingIntegrationTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.web.reactive.result.method.annotation;
 
+import java.net.URI;
 import java.time.Duration;
 
 import org.junit.Test;
@@ -23,11 +24,16 @@ import org.reactivestreams.Publisher;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpHeaders;
+import org.springframework.http.RequestEntity;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.reactive.config.EnableWebFlux;
+import org.springframework.web.server.adapter.ForwardedHeaderTransformer;
 
 import static org.junit.Assert.*;
 
@@ -46,7 +52,7 @@ public class RequestMappingIntegrationTests extends AbstractRequestMappingIntegr
 	@Override
 	protected ApplicationContext initApplicationContext() {
 		AnnotationConfigApplicationContext wac = new AnnotationConfigApplicationContext();
-		wac.register(WebConfig.class, TestRestController.class);
+		wac.register(WebConfig.class, TestRestController.class, LocalConfig.class);
 		wac.refresh();
 		return wac;
 	}
@@ -62,6 +68,20 @@ public class RequestMappingIntegrationTests extends AbstractRequestMappingIntegr
 		assertEquals(3, headers.getContentLength());
 	}
 
+	@Test
+	public void forwardedHeaders() {
+
+		// One integration test to verify triggering of Forwarded header support.
+		// More fine-grained tests in ForwardedHeaderTransformerTests.
+
+		RequestEntity<Void> request = RequestEntity
+				.get(URI.create("http://localhost:" + this.port + "/uri"))
+				.header("Forwarded", "host=84.198.58.199;proto=https")
+				.build();
+		ResponseEntity<String> entity = getRestTemplate().exchange(request, String.class);
+		assertEquals("https://84.198.58.199/uri", entity.getBody());
+	}
+
 	@Test
 	public void stream() throws Exception {
 		String[] expected = {"0", "1", "2", "3", "4"};
@@ -84,10 +104,25 @@ public class RequestMappingIntegrationTests extends AbstractRequestMappingIntegr
 			return "Foo";
 		}
 
+		@GetMapping("/uri")
+		public String uri(ServerHttpRequest request) {
+			return request.getURI().toString();
+		}
+
 		@GetMapping("/stream")
 		public Publisher<Long> stream() {
 			return testInterval(Duration.ofMillis(50), 5);
 		}
 	}
 
+
+	@Configuration
+	static class LocalConfig {
+
+		@Bean
+		public ForwardedHeaderTransformer forwardedHeaderTransformer() {
+			return new ForwardedHeaderTransformer();
+		}
+	}
+
 }