Fix ResourceUrlEncodingFilter lifecycle

Prior to this commit, the `ResourceUrlEncodingFilter` would wrap the
response and keep a reference to the request. When
`HttpServletResponse.encodeURL` is later called during view rendering,
the filter looks at the request and extracts context mapping information
in order to resolve resource paths in views.

This approach is flawed, when the filter is used with JSPs - if the
request is forwarded to the container by the `InternalResourceView`,
the request information is overwritten by the container. When the view
is being rendered, the information available in the request is outdated
and does not allow to correctly compute that context mapping
information.

This commit ensures that that information is being extracted from the
request as soon as the `ResourceUrlProvider` is set as a request
attribute.

Issue: SPR-17421
(Cherry-picked from 50a47691)

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceUrlEncodingFilter.java

 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -22,6 +22,7 @@ import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletRequestWrapper;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpServletResponseWrapper;
 
@@ -53,73 +54,74 @@ public class ResourceUrlEncodingFilter extends GenericFilterBean {
 	public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
 			throws IOException, ServletException {
 		if (!(request instanceof HttpServletRequest) || !(response instanceof HttpServletResponse)) {
-			throw new ServletException("ResourceUrlEncodingFilter just supports HTTP requests");
+			throw new ServletException("ResourceUrlEncodingFilter only supports HTTP requests");
 		}
-		HttpServletRequest httpRequest = (HttpServletRequest) request;
-		HttpServletResponse httpResponse = (HttpServletResponse) response;
-		filterChain.doFilter(httpRequest, new ResourceUrlEncodingResponseWrapper(httpRequest, httpResponse));
+		ResourceUrlEncodingRequestWrapper wrappedRequest =
+				new ResourceUrlEncodingRequestWrapper((HttpServletRequest) request);
+		ResourceUrlEncodingResponseWrapper wrappedResponse =
+				new ResourceUrlEncodingResponseWrapper(wrappedRequest, (HttpServletResponse) response);
+		filterChain.doFilter(wrappedRequest, wrappedResponse);
 	}
 
+	private static class ResourceUrlEncodingRequestWrapper extends HttpServletRequestWrapper {
 
-	private static class ResourceUrlEncodingResponseWrapper extends HttpServletResponseWrapper {
-
-		private final HttpServletRequest request;
+		@Nullable
+		private ResourceUrlProvider resourceUrlProvider;
 
-		/* Cache the index and prefix of the path within the DispatcherServlet mapping */
 		@Nullable
 		private Integer indexLookupPath;
 
 		private String prefixLookupPath = "";
 
-		public ResourceUrlEncodingResponseWrapper(HttpServletRequest request, HttpServletResponse wrapped) {
-			super(wrapped);
-			this.request = request;
+		ResourceUrlEncodingRequestWrapper(HttpServletRequest request) {
+			super(request);
 		}
 
 		@Override
-		public String encodeURL(String url) {
-			ResourceUrlProvider resourceUrlProvider = getResourceUrlProvider();
-			if (resourceUrlProvider == null) {
-				logger.debug("Request attribute exposing ResourceUrlProvider not found");
-				return super.encodeURL(url);
-			}
-
-			int index = initLookupPath(resourceUrlProvider);
-			if (url.startsWith(this.prefixLookupPath)) {
-				int suffixIndex = getQueryParamsIndex(url);
-				String suffix = url.substring(suffixIndex);
-				String lookupPath = url.substring(index, suffixIndex);
-				lookupPath = resourceUrlProvider.getForLookupPath(lookupPath);
-				if (lookupPath != null) {
-					return super.encodeURL(this.prefixLookupPath + lookupPath + suffix);
+		public void setAttribute(String name, Object o) {
+			super.setAttribute(name, o);
+			if (ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR.equals(name)) {
+				if(o instanceof ResourceUrlProvider) {
+					initLookupPath((ResourceUrlProvider) o);
 				}
 			}
 
-			return super.encodeURL(url);
-		}
-
-		@Nullable
-		private ResourceUrlProvider getResourceUrlProvider() {
-			return (ResourceUrlProvider) this.request.getAttribute(
-					ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR);
 		}
 
-		private int initLookupPath(ResourceUrlProvider urlProvider) {
+		private void initLookupPath(ResourceUrlProvider urlProvider) {
+			this.resourceUrlProvider = urlProvider;
 			if (this.indexLookupPath == null) {
-				UrlPathHelper pathHelper = urlProvider.getUrlPathHelper();
-				String requestUri = pathHelper.getRequestUri(this.request);
-				String lookupPath = pathHelper.getLookupPathForRequest(this.request);
+				UrlPathHelper pathHelper = this.resourceUrlProvider.getUrlPathHelper();
+				String requestUri = pathHelper.getRequestUri(this);
+				String lookupPath = pathHelper.getLookupPathForRequest(this);
 				this.indexLookupPath = requestUri.lastIndexOf(lookupPath);
 				this.prefixLookupPath = requestUri.substring(0, this.indexLookupPath);
 				if ("/".equals(lookupPath) && !"/".equals(requestUri)) {
-					String contextPath = pathHelper.getContextPath(this.request);
+					String contextPath = pathHelper.getContextPath(this);
 					if (requestUri.equals(contextPath)) {
 						this.indexLookupPath = requestUri.length();
 						this.prefixLookupPath = requestUri;
 					}
 				}
 			}
-			return this.indexLookupPath;
+		}
+
+		@Nullable
+		public String resolveUrlPath(String url) {
+			if (this.resourceUrlProvider == null) {
+				logger.debug("Request attribute exposing ResourceUrlProvider not found");
+				return null;
+			}
+			if (url.startsWith(this.prefixLookupPath)) {
+				int suffixIndex = getQueryParamsIndex(url);
+				String suffix = url.substring(suffixIndex);
+				String lookupPath = url.substring(this.indexLookupPath, suffixIndex);
+				lookupPath = this.resourceUrlProvider.getForLookupPath(lookupPath);
+				if (lookupPath != null) {
+					return this.prefixLookupPath + lookupPath + suffix;
+				}
+			}
+			return null;
 		}
 
 		private int getQueryParamsIndex(String url) {
@@ -128,4 +130,24 @@ public class ResourceUrlEncodingFilter extends GenericFilterBean {
 		}
 	}
 
-}
+
+	private static class ResourceUrlEncodingResponseWrapper extends HttpServletResponseWrapper {
+
+		private final ResourceUrlEncodingRequestWrapper request;
+
+		ResourceUrlEncodingResponseWrapper(ResourceUrlEncodingRequestWrapper request, HttpServletResponse wrapped) {
+			super(wrapped);
+			this.request = request;
+		}
+
+		@Override
+		public String encodeURL(String url) {
+			String urlPath = this.request.resolveUrlPath(url);
+			if (urlPath != null) {
+				return super.encodeURL(urlPath);
+			}
+			return super.encodeURL(url);
+		}
+	}
+
+}
\ No newline at end of file

spring-webmvc/src/test/java/org/springframework/web/servlet/resource/ResourceUrlEncodingFilterTests.java

@@ -38,7 +38,7 @@ public class ResourceUrlEncodingFilterTests {
 
 	private ResourceUrlEncodingFilter filter;
 
-	private ResourceUrlProvider resourceUrlProvider;
+	private ResourceUrlProvider urlProvider;
 
 	@Before
 	public void createFilter() throws Exception {
@@ -49,16 +49,16 @@ public class ResourceUrlEncodingFilterTests {
 		List<ResourceResolver> resolvers = Arrays.asList(versionResolver, pathResolver);
 
 		this.filter = new ResourceUrlEncodingFilter();
-		this.resourceUrlProvider = createResourceUrlProvider(resolvers);
+		this.urlProvider = createResourceUrlProvider(resolvers);
 	}
 
 	@Test
 	public void encodeURL() throws Exception {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/");
-		request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.resourceUrlProvider);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
 			String result = ((HttpServletResponse) res).encodeURL("/resources/bar.css");
 			assertEquals("/resources/bar-11e16cf79faee7ac698c805cf28248d2.css", result);
 		});
@@ -68,10 +68,26 @@ public class ResourceUrlEncodingFilterTests {
 	public void encodeURLWithContext() throws Exception {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/context/foo");
 		request.setContextPath("/context");
-		request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.resourceUrlProvider);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
+			String result = ((HttpServletResponse) res).encodeURL("/context/resources/bar.css");
+			assertEquals("/context/resources/bar-11e16cf79faee7ac698c805cf28248d2.css", result);
+		});
+	}
+
+
+	@Test
+	public void encodeUrlWithContextAndForwardedRequest() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/context/foo");
+		request.setContextPath("/context");
+		MockHttpServletResponse response = new MockHttpServletResponse();
+
+		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
+			request.setRequestURI("/forwarded");
+			request.setContextPath("/");
 			String result = ((HttpServletResponse) res).encodeURL("/context/resources/bar.css");
 			assertEquals("/context/resources/bar-11e16cf79faee7ac698c805cf28248d2.css", result);
 		});
@@ -82,10 +98,10 @@ public class ResourceUrlEncodingFilterTests {
 	public void encodeContextPathUrlWithoutSuffix() throws Exception {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/context");
 		request.setContextPath("/context");
-		request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.resourceUrlProvider);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
 			String result = ((HttpServletResponse) res).encodeURL("/context/resources/bar.css");
 			assertEquals("/context/resources/bar-11e16cf79faee7ac698c805cf28248d2.css", result);
 		});
@@ -95,10 +111,10 @@ public class ResourceUrlEncodingFilterTests {
 	public void encodeContextPathUrlWithSuffix() throws Exception {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/context/");
 		request.setContextPath("/context");
-		request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.resourceUrlProvider);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
 			String result = ((HttpServletResponse) res).encodeURL("/context/resources/bar.css");
 			assertEquals("/context/resources/bar-11e16cf79faee7ac698c805cf28248d2.css", result);
 		});
@@ -109,10 +125,10 @@ public class ResourceUrlEncodingFilterTests {
 	public void encodeEmptyURLWithContext() throws Exception {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/context/foo");
 		request.setContextPath("/context");
-		request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.resourceUrlProvider);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
 			String result = ((HttpServletResponse) res).encodeURL("?foo=1");
 			assertEquals("?foo=1", result);
 		});
@@ -123,10 +139,10 @@ public class ResourceUrlEncodingFilterTests {
 	public void encodeURLWithRequestParams() throws Exception {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/foo");
 		request.setContextPath("/");
-		request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.resourceUrlProvider);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
 			String result = ((HttpServletResponse) res).encodeURL("/resources/bar.css?foo=bar&url=http://example.org");
 			assertEquals("/resources/bar-11e16cf79faee7ac698c805cf28248d2.css?foo=bar&url=http://example.org", result);
 		});
@@ -138,10 +154,10 @@ public class ResourceUrlEncodingFilterTests {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/context-path/index");
 		request.setContextPath("/context-path");
 		request.setServletPath("");
-		request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.resourceUrlProvider);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		this.filter.doFilter(request, response, (req, res) -> {
+			req.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, this.urlProvider);
 			String result = ((HttpServletResponse) res).encodeURL("index?key=value");
 			assertEquals("index?key=value", result);
 		});

spring-webmvc/src/test/java/org/springframework/web/servlet/resource/ResourceUrlProviderJavaConfigTests.java

 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -55,8 +55,6 @@ public class ResourceUrlProviderJavaConfigTests {
 	@Before
 	@SuppressWarnings("resource")
 	public void setup() throws Exception {
-		this.filterChain = new MockFilterChain(this.servlet, new ResourceUrlEncodingFilter());
-
 		AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
 		context.setServletContext(new MockServletContext());
 		context.register(WebConfig.class);
@@ -66,8 +64,13 @@ public class ResourceUrlProviderJavaConfigTests {
 		this.request.setContextPath("/myapp");
 		this.response = new MockHttpServletResponse();
 
-		Object urlProvider = context.getBean(ResourceUrlProvider.class);
-		this.request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, urlProvider);
+		this.filterChain = new MockFilterChain(this.servlet,
+				new ResourceUrlEncodingFilter(),
+				(request, response, chain) -> {
+					Object urlProvider = context.getBean(ResourceUrlProvider.class);
+					request.setAttribute(ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR, urlProvider);
+					chain.doFilter(request, response);
+				});
 	}
 
 	@Test