Add "hosts" property to RedirectView

Issue: SPR-13693

spring-webmvc/src/main/java/org/springframework/web/servlet/view/RedirectView.java

@@ -104,6 +104,8 @@ public class RedirectView extends AbstractUrlBasedView implements SmartView {
 
 	private boolean propagateQueryParams = false;
 
+	private String[] hosts;
+
 
 	/**
 	 * Constructor for use as a bean.
@@ -252,6 +254,27 @@ public class RedirectView extends AbstractUrlBasedView implements SmartView {
 		return this.propagateQueryParams;
 	}
 
+	/**
+	 * Configure one or more hosts associated with the application. All other
+	 * hosts will be considered external hosts. In effect this property
+	 * provides a way turn off encoding via
+	 * {@link HttpServletResponse#encodeRedirectURL} for URLs that have a host
+	 * and that host is not listed as a known host.
+	 * <p>If not set (the default) all URLs are encoded through the response.
+	 * @param hosts one or more application hosts
+	 * @since 4.3
+	 */
+	public void setHosts(String[] hosts) {
+		this.hosts = hosts;
+	}
+
+	/**
+	 * Return the configured application hosts.
+	 */
+	public String[] getHosts() {
+		return this.hosts;
+	}
+
 	/**
 	 * Returns "true" indicating this view performs a redirect.
 	 */
@@ -583,29 +606,55 @@ public class RedirectView extends AbstractUrlBasedView implements SmartView {
 	protected void sendRedirect(HttpServletRequest request, HttpServletResponse response,
 			String targetUrl, boolean http10Compatible) throws IOException {
 
-		String encodedRedirectURL = response.encodeRedirectURL(targetUrl);
+		String encodedURL = (isRemoteHost(targetUrl) ? targetUrl : response.encodeRedirectURL(targetUrl));
 		if (http10Compatible) {
 			HttpStatus attributeStatusCode = (HttpStatus) request.getAttribute(View.RESPONSE_STATUS_ATTRIBUTE);
 			if (this.statusCode != null) {
 				response.setStatus(this.statusCode.value());
-				response.setHeader("Location", encodedRedirectURL);
+				response.setHeader("Location", encodedURL);
 			}
 			else if (attributeStatusCode != null) {
 				response.setStatus(attributeStatusCode.value());
-				response.setHeader("Location", encodedRedirectURL);
+				response.setHeader("Location", encodedURL);
 			}
 			else {
 				// Send status code 302 by default.
-				response.sendRedirect(encodedRedirectURL);
+				response.sendRedirect(encodedURL);
 			}
 		}
 		else {
 			HttpStatus statusCode = getHttp11StatusCode(request, response, targetUrl);
 			response.setStatus(statusCode.value());
-			response.setHeader("Location", encodedRedirectURL);
+			response.setHeader("Location", encodedURL);
 		}
 	}
 
+	/**
+	 * Whether the given targetUrl has a host that is a "foreign" system in which
+	 * case {@link HttpServletResponse#encodeRedirectURL} will not be applied.
+	 * This method returns {@code true} if the {@link #setHosts(String[])}
+	 * property is configured and the target URL has a host that does not match.
+	 * @param targetUrl the target redirect URL
+	 * @return {@code true} the target URL has a remote host, {@code false} if it
+	 * the URL does not have a host or the "host" property is not configured.
+	 * @since 4.3
+	 */
+	protected boolean isRemoteHost(String targetUrl) {
+		if (ObjectUtils.isEmpty(getHosts())) {
+			return false;
+		}
+		String targetHost = UriComponentsBuilder.fromUriString(targetUrl).build().getHost();
+		if (StringUtils.isEmpty(targetHost)) {
+			return false;
+		}
+		for (String host : getHosts()) {
+			if (targetHost.equals(host)) {
+				return false;
+			}
+		}
+		return true;
+	}
+
 	/**
 	 * Determines the status code to use for HTTP 1.1 compatible requests.
 	 * <p>The default implementation returns the {@link #setStatusCode(HttpStatus) statusCode}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/UrlBasedViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -20,6 +20,7 @@ import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Properties;
+import javax.servlet.http.HttpServletResponse;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.Ordered;
@@ -112,6 +113,8 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 
 	private boolean redirectHttp10Compatible = true;
 
+	private String[] redirectHosts;
+
 	private String requestContextAttribute;
 
 	/** Map of static attributes, keyed by attribute name (String) */
@@ -253,6 +256,27 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 		return this.redirectHttp10Compatible;
 	}
 
+	/**
+	 * Configure one or more hosts associated with the application. All other
+	 * hosts will be considered external hosts. In effect this property
+	 * provides a way turn off encoding on redirect via
+	 * {@link HttpServletResponse#encodeRedirectURL} for URLs that have a host
+	 * and that host is not listed as a known host.
+	 * <p>If not set (the default) all URLs are encoded through the response.
+	 * @param redirectHosts one or more application hosts
+	 * @since 4.3
+	 */
+	public void setRedirectHosts(String[] redirectHosts) {
+		this.redirectHosts = redirectHosts;
+	}
+
+	/**
+	 * Return the configured application hosts for redirect purposes.
+	 */
+	public String[] getRedirectHosts() {
+		return this.redirectHosts;
+	}
+
 	/**
 	 * Set the name of the RequestContext attribute for all views.
 	 * @param requestContextAttribute name of the RequestContext attribute
@@ -435,6 +459,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 		if (viewName.startsWith(REDIRECT_URL_PREFIX)) {
 			String redirectUrl = viewName.substring(REDIRECT_URL_PREFIX.length());
 			RedirectView view = new RedirectView(redirectUrl, isRedirectContextRelative(), isRedirectHttp10Compatible());
+			view.setHosts(getRedirectHosts());
 			return applyLifecycleMethods(viewName, view);
 		}
 		// Check for special "forward:" prefix.

spring-webmvc/src/test/java/org/springframework/web/servlet/view/RedirectViewTests.java

@@ -43,6 +43,7 @@ import org.springframework.web.servlet.support.SessionFlashMapManager;
 import org.springframework.web.util.WebUtils;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.BDDMockito.mock;
@@ -205,6 +206,24 @@ public class RedirectViewTests {
 		}
 	}
 
+	// SPR-13693
+
+	@Test
+	public void remoteHost() throws Exception {
+		RedirectView rv = new RedirectView();
+
+		assertFalse(rv.isRemoteHost("http://url.somewhere.com"));
+		assertFalse(rv.isRemoteHost("/path"));
+		assertFalse(rv.isRemoteHost("http://url.somewhereelse.com"));
+
+		rv.setHosts(new String[] {"url.somewhere.com"});
+
+		assertFalse(rv.isRemoteHost("http://url.somewhere.com"));
+		assertFalse(rv.isRemoteHost("/path"));
+		assertTrue(rv.isRemoteHost("http://url.somewhereelse.com"));
+
+	}
+
 	@Test
 	public void emptyMap() throws Exception {
 		String url = "/myUrl";