Merge pull request #29333 from terminux

* gh-29333:
  Polish "Configure ForwardedHeaderFilter with Tomcat's use relative redirects"
  Configure ForwardedHeaderFilter with Tomcat's use relative redirects

Closes gh-29333

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/ServletWebServerFactoryAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -85,15 +85,35 @@ public class ServletWebServerFactoryAutoConfiguration {
 		return new TomcatServletWebServerFactoryCustomizer(serverProperties);
 	}
 
-	@Bean
-	@ConditionalOnMissingFilterBean(ForwardedHeaderFilter.class)
+	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnProperty(value = "server.forward-headers-strategy", havingValue = "framework")
-	public FilterRegistrationBean<ForwardedHeaderFilter> forwardedHeaderFilter() {
-		ForwardedHeaderFilter filter = new ForwardedHeaderFilter();
-		FilterRegistrationBean<ForwardedHeaderFilter> registration = new FilterRegistrationBean<>(filter);
-		registration.setDispatcherTypes(DispatcherType.REQUEST, DispatcherType.ASYNC, DispatcherType.ERROR);
-		registration.setOrder(Ordered.HIGHEST_PRECEDENCE);
-		return registration;
+	@ConditionalOnMissingFilterBean(ForwardedHeaderFilter.class)
+	static class ForwardedHeaderFilterConfiguration {
+
+		@Bean
+		@ConditionalOnClass(name = "org.apache.catalina.startup.Tomcat")
+		@ConditionalOnMissingFilterBean(ForwardedHeaderFilter.class)
+		ForwardedHeaderFilterCustomizer tomcatForwardedHeaderFilterCustomizer(ServerProperties serverProperties) {
+			return (filter) -> filter.setRelativeRedirects(serverProperties.getTomcat().isUseRelativeRedirects());
+		}
+
+		@Bean
+		FilterRegistrationBean<ForwardedHeaderFilter> forwardedHeaderFilter(
+				ObjectProvider<ForwardedHeaderFilterCustomizer> customizerProvider) {
+			ForwardedHeaderFilter filter = new ForwardedHeaderFilter();
+			customizerProvider.ifAvailable((customizer) -> customizer.customize(filter));
+			FilterRegistrationBean<ForwardedHeaderFilter> registration = new FilterRegistrationBean<>(filter);
+			registration.setDispatcherTypes(DispatcherType.REQUEST, DispatcherType.ASYNC, DispatcherType.ERROR);
+			registration.setOrder(Ordered.HIGHEST_PRECEDENCE);
+			return registration;
+		}
+
+	}
+
+	interface ForwardedHeaderFilterCustomizer {
+
+		void customize(ForwardedHeaderFilter filter);
+
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/ServletWebServerFactoryAutoConfigurationTests.java

@@ -352,6 +352,7 @@ class ServletWebServerFactoryAutoConfigurationTests {
 			assertThat(context).hasSingleBean(FilterRegistrationBean.class);
 			Filter filter = context.getBean(FilterRegistrationBean.class).getFilter();
 			assertThat(filter).isInstanceOf(ForwardedHeaderFilter.class);
+			assertThat(filter).extracting("relativeRedirects").isEqualTo(false);
 		});
 	}
 
@@ -368,6 +369,48 @@ class ServletWebServerFactoryAutoConfigurationTests {
 				.run((context) -> assertThat(context).hasSingleBean(FilterRegistrationBean.class));
 	}
 
+	@Test
+	void relativeRedirectsShouldBeEnabledWhenUsingTomcatContainerAndUseRelativeRedirects() {
+		WebApplicationContextRunner runner = new WebApplicationContextRunner(
+				AnnotationConfigServletWebServerApplicationContext::new)
+						.withConfiguration(AutoConfigurations.of(ServletWebServerFactoryAutoConfiguration.class))
+						.withPropertyValues("server.forward-headers-strategy=framework",
+								"server.tomcat.use-relative-redirects=true");
+		runner.run((context) -> {
+			Filter filter = context.getBean(FilterRegistrationBean.class).getFilter();
+			assertThat(filter).isInstanceOf(ForwardedHeaderFilter.class);
+			assertThat(filter).extracting("relativeRedirects").isEqualTo(true);
+		});
+	}
+
+	@Test
+	void relativeRedirectsShouldNotBeEnabledWhenUsingTomcatContainerAndNotUsingRelativeRedirects() {
+		WebApplicationContextRunner runner = new WebApplicationContextRunner(
+				AnnotationConfigServletWebServerApplicationContext::new)
+						.withConfiguration(AutoConfigurations.of(ServletWebServerFactoryAutoConfiguration.class))
+						.withPropertyValues("server.forward-headers-strategy=framework",
+								"server.tomcat.use-relative-redirects=false");
+		runner.run((context) -> {
+			Filter filter = context.getBean(FilterRegistrationBean.class).getFilter();
+			assertThat(filter).isInstanceOf(ForwardedHeaderFilter.class);
+			assertThat(filter).extracting("relativeRedirects").isEqualTo(false);
+		});
+	}
+
+	@Test
+	void relativeRedirectsShouldNotBeEnabledWhenNotUsingTomcatContainer() {
+		WebApplicationContextRunner runner = new WebApplicationContextRunner(
+				AnnotationConfigServletWebServerApplicationContext::new)
+						.withClassLoader(new FilteredClassLoader(Tomcat.class))
+						.withConfiguration(AutoConfigurations.of(ServletWebServerFactoryAutoConfiguration.class))
+						.withPropertyValues("server.forward-headers-strategy=framework");
+		runner.run((context) -> {
+			Filter filter = context.getBean(FilterRegistrationBean.class).getFilter();
+			assertThat(filter).isInstanceOf(ForwardedHeaderFilter.class);
+			assertThat(filter).extracting("relativeRedirects").isEqualTo(false);
+		});
+	}
+
 	private ContextConsumer<AssertableWebApplicationContext> verifyContext() {
 		return this::verifyContext;
 	}