Add Support for Clear Site Data on Logout

Added an implementation of HeaderWriter for Clear-Site-Data HTTP
response header as welll as an implementation of LogoutHanlder
that accepts an implementation of HeaderWriter to write headers.

- Added ClearSiteDataHeaderWriter and HeaderWriterLogoutHandler
that implements HeaderWriter and LogoutHandler respectively
- Added unit tests for both implementations's behaviours
- Integration tests for HeaderWriterLogoutHandler that uses
ClearSiteDataHeaderWriter
- Updated the documentation to include link to
HeaderWriterLogoutHandler

Fixes gh-4187

config/src/test/java/org/springframework/security/config/annotation/web/configurers/LogoutConfigurerClearSiteDataTests.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2002-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.config.annotation.web.configurers;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
+import org.springframework.security.config.test.SpringTestRule;
+import org.springframework.security.test.context.annotation.SecurityTestExecutionListeners;
+import org.springframework.security.test.context.support.WithMockUser;
+import org.springframework.security.web.authentication.logout.HeaderWriterLogoutHandler;
+import org.springframework.security.web.header.writers.ClearSiteDataHeaderWriter;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
+
+import static org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors.csrf;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.header;
+
+/**
+ *
+ * Tests for {@link HeaderWriterLogoutHandler} that passing {@link ClearSiteDataHeaderWriter}
+ * implementation.
+ *
+ * @author Rafiullah Hamedy
+ *
+ */
+@RunWith(SpringRunner.class)
+@SecurityTestExecutionListeners
+public class LogoutConfigurerClearSiteDataTests {
+
+	private static final String CLEAR_SITE_DATA_HEADER = "Clear-Site-Data";
+
+	private static final String[] SOURCE = {"cache", "cookies", "storage", "executionContexts"};
+
+	private static final String HEADER_VALUE = "\"cache\", \"cookies\", \"storage\", \"executionContexts\"";
+
+	@Rule
+	public final SpringTestRule spring = new SpringTestRule();
+
+	@Autowired
+	MockMvc mvc;
+
+	@Test
+	@WithMockUser
+	public void logoutWhenRequestTypeGetThenHeaderNotPresentt() throws Exception {
+		this.spring.register(HttpLogoutConfig.class).autowire();
+
+		this.mvc.perform(get("/logout").secure(true).with(csrf()))
+			.andExpect(header().doesNotExist(CLEAR_SITE_DATA_HEADER));
+	}
+
+	@Test
+	@WithMockUser
+	public void logoutWhenRequestTypePostAndNotSecureThenHeaderNotPresent() throws Exception {
+		this.spring.register(HttpLogoutConfig.class).autowire();
+
+		this.mvc.perform(post("/logout").with(csrf()))
+			.andExpect(header().doesNotExist(CLEAR_SITE_DATA_HEADER));
+	}
+
+	@Test
+	@WithMockUser
+	public void logoutWhenRequestTypePostAndSecureThenHeaderIsPresent() throws Exception {
+		this.spring.register(HttpLogoutConfig.class).autowire();
+
+		this.mvc.perform(post("/logout").secure(true).with(csrf()))
+			.andExpect(header().stringValues(CLEAR_SITE_DATA_HEADER, HEADER_VALUE));
+	}
+
+	@EnableWebSecurity
+	static class HttpLogoutConfig extends WebSecurityConfigurerAdapter {
+		@Override
+		protected void configure(HttpSecurity http) throws Exception {
+			http
+				.logout()
+					.addLogoutHandler(new HeaderWriterLogoutHandler(new ClearSiteDataHeaderWriter(SOURCE)));
+		}
+	}
+}