Add RelativeRedirectFilter

spring-web/src/main/java/org/springframework/web/filter/ForwardedHeaderFilter.java

@@ -102,7 +102,8 @@ public class ForwardedHeaderFilter extends OncePerRequestFilter {
 	/**
 	 * Enables mode in which only the HttpServletRequest is modified. This means that
 	 * {@link HttpServletResponse#sendRedirect(String)} will only work when the application is configured to use
-	 * relative redirects. This can be done with Servlet Container specific setup. For example,  using Tomcat's
+	 * relative redirects. This can be done by placing {@link RelativeRedirectFilter} after this Filter or Servlet
+	 * Container specific setup. For example, using Tomcat's
 	 * <a href="https://tomcat.apache.org/tomcat-8.0-doc/config/context.html#Common_Attributes">useRelativeRedirects</a>
 	 * attribute.
 	 *

spring-web/src/main/java/org/springframework/web/filter/RelativeRedirectFilter.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2002-2017 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.web.filter;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.util.Assert;
+
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpServletResponseWrapper;
+import java.io.IOException;
+
+/**
+ * Overrides the {@link HttpServletResponse#sendRedirect(String)} to set the "Location" header and the HTTP Status
+ * directly to avoid the Servlet Container from creating an absolute URL. This allows redirects that have a relative
+ * "Location" that ensures support for <a href="https://tools.ietf.org/html/rfc7231#section-7.1.2">RFC 7231 Section
+ * 7.1.2</a>. It should be noted that while relative redirects are more efficient, they may not work with reverse
+ * proxies under some configurations.
+ *
+ * @author Rob Winch
+ * @since 4.3.10
+ */
+public class RelativeRedirectFilter extends OncePerRequestFilter {
+	private HttpStatus sendRedirectHttpStatus = HttpStatus.FOUND;
+
+	/**
+	 * Sets the HTTP Status to be used when {@code HttpServletResponse#sendRedirect(String)} is invoked.
+	 * @param sendRedirectHttpStatus the 3xx HTTP Status to be used when
+	 * {@code HttpServletResponse#sendRedirect(String)} is invoked. The default is {@code HttpStatus.FOUND}.
+	 */
+	public void setSendRedirectHttpStatus(HttpStatus sendRedirectHttpStatus) {
+		Assert.notNull(sendRedirectHttpStatus, "HttpStatus is required");
+		if(!sendRedirectHttpStatus.is3xxRedirection()) {
+			throw new IllegalArgumentException("sendRedirectHttpStatus should be for redirection. Got " + sendRedirectHttpStatus);
+		}
+		this.sendRedirectHttpStatus = sendRedirectHttpStatus;
+	}
+
+	@Override
+	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
+		filterChain.doFilter(request, new RelativeRedirectResponse(response));
+	}
+
+	/**
+	 * Modifies {@link #sendRedirect(String)} to explicitly set the "Location" header and an HTTP status code to avoid
+	 * containers from rewriting the location to be an absolute URL.
+	 *
+	 * @author Rob Winch
+	 * @since 4.3.10
+	 */
+	private class RelativeRedirectResponse extends HttpServletResponseWrapper {
+
+		/**
+		 * Constructs a response adaptor wrapping the given response.
+		 *
+		 * @param response
+		 * @throws IllegalArgumentException if the response is null
+		 */
+		public RelativeRedirectResponse(HttpServletResponse response) {
+			super(response);
+		}
+
+		@Override
+		public void sendRedirect(String location) throws IOException {
+			setHeader(HttpHeaders.LOCATION, location);
+			setStatus(sendRedirectHttpStatus.value());
+		}
+	}
+}

spring-web/src/test/java/org/springframework/web/filter/RelativeRedirectFilterTests.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2002-2017 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.web.filter;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.InOrder;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.mock.web.test.MockFilterChain;
+import org.springframework.mock.web.test.MockHttpServletRequest;
+
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * @author Rob Winch
+ * @since 4.3.10
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class RelativeRedirectFilterTests {
+	@Mock
+	HttpServletResponse response;
+
+	RelativeRedirectFilter filter = new RelativeRedirectFilter();
+
+	@Test(expected = IllegalArgumentException.class)
+	public void sendRedirectHttpStatusWhenNullThenIllegalArgumentException() {
+		this.filter.setSendRedirectHttpStatus(null);
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void sendRedirectHttpStatusWhenNot3xxThenIllegalArgumentException() {
+		this.filter.setSendRedirectHttpStatus(HttpStatus.OK);
+	}
+
+	@Test
+	public void doFilterSendRedirectWhenDefaultsThenLocationAnd302() throws Exception {
+		String location = "/foo";
+
+		sendRedirect(location);
+
+		InOrder inOrder = Mockito.inOrder(this.response);
+		inOrder.verify(this.response).setHeader(HttpHeaders.LOCATION, location);
+		inOrder.verify(this.response).setStatus(HttpStatus.FOUND.value());
+	}
+
+	@Test
+	public void doFilterSendRedirectWhenCustomSendRedirectHttpStatusThenLocationAnd301() throws Exception {
+		String location = "/foo";
+		HttpStatus status = HttpStatus.MOVED_PERMANENTLY;
+		this.filter.setSendRedirectHttpStatus(status);
+		sendRedirect(location);
+
+		InOrder inOrder = Mockito.inOrder(this.response);
+		inOrder.verify(this.response).setHeader(HttpHeaders.LOCATION, location);
+		inOrder.verify(this.response).setStatus(status.value());
+	}
+
+	private void sendRedirect(String location) throws Exception {
+		MockFilterChain chain = new MockFilterChain();
+
+		filter.doFilterInternal(new MockHttpServletRequest(), response, chain);
+
+		HttpServletResponse wrappedResponse = (HttpServletResponse) chain.getResponse();
+		wrappedResponse.sendRedirect(location);
+	}
+}