From 7ee687c79866f59b678c07f083b411e0a9b0d134 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Edd=C3=BA=20Mel=C3=A9ndez?= <eddu.melendez@gmail.com>
Date: Wed, 1 Jun 2016 19:58:46 +1000
Subject: [PATCH] Support X-Forwarded-Prefix in ForwardedHeaderFilter

See SPR-14270
---
 .../web/filter/ForwardedHeaderFilter.java     | 25 ++++++++++++-
 .../filter/ForwardedHeaderFilterTests.java    | 37 +++++++++++++++++++
 2 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/web/filter/ForwardedHeaderFilter.java b/spring-web/src/main/java/org/springframework/web/filter/ForwardedHeaderFilter.java
index c21a3ac0c6..c16fb46f9b 100644
--- a/spring-web/src/main/java/org/springframework/web/filter/ForwardedHeaderFilter.java
+++ b/spring-web/src/main/java/org/springframework/web/filter/ForwardedHeaderFilter.java
@@ -34,6 +34,7 @@ import org.springframework.http.HttpRequest;
 import org.springframework.http.server.ServletServerHttpRequest;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
+import org.springframework.util.StringUtils;
 import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 import org.springframework.web.util.UrlPathHelper;
@@ -48,6 +49,7 @@ import org.springframework.web.util.UrlPathHelper;
  * reflects the client-originated protocol and address.
  *
  * @author Rossen Stoyanchev
+ * @author Eddú Meléndez
  * @since 4.3
  */
 public class ForwardedHeaderFilter extends OncePerRequestFilter {
@@ -143,13 +145,32 @@ public class ForwardedHeaderFilter extends OncePerRequestFilter {
 			this.host = uriComponents.getHost();
 			this.port = (port == -1 ? (this.secure ? 443 : 80) : port);
 
-			this.contextPath = (pathHelper != null ? pathHelper.getContextPath(request) : request.getContextPath());
-			this.requestUri = (pathHelper != null ? pathHelper.getRequestUri(request) : request.getRequestURI());
+			this.contextPath = contextPath(request, pathHelper);
+			this.requestUri = requestUri(request, pathHelper);
 			this.requestUrl = initRequestUrl(this.scheme, this.host, port, this.requestUri);
 
 			this.headers = initHeaders(request);
 		}
 
+		private static String contextPath(HttpServletRequest request, ContextPathHelper pathHelper) {
+			String contextPath = (pathHelper != null ? pathHelper.getContextPath(request) : request.getContextPath());
+			return prependForwardedPrefix(request, contextPath);
+		}
+
+		private static String requestUri(HttpServletRequest request, ContextPathHelper pathHelper) {
+			String requestUri = (pathHelper != null ? pathHelper.getRequestUri(request) : request.getRequestURI());
+			return prependForwardedPrefix(request, requestUri);
+		}
+
+		private static String prependForwardedPrefix(HttpServletRequest request, String value) {
+			String header = request.getHeader("X-Forwarded-Prefix");
+			if (StringUtils.hasText(header)) {
+				value = header + value;
+			}
+			UriComponents uriComponents = UriComponentsBuilder.fromUriString(value).build();
+			return uriComponents.toUriString();
+		}
+
 		private static StringBuffer initRequestUrl(String scheme, String host, int port, String path) {
 			StringBuffer sb = new StringBuffer();
 			sb.append(scheme).append("://").append(host);
diff --git a/spring-web/src/test/java/org/springframework/web/filter/ForwardedHeaderFilterTests.java b/spring-web/src/test/java/org/springframework/web/filter/ForwardedHeaderFilterTests.java
index bd7a375bd6..c6d54b22bd 100644
--- a/spring-web/src/test/java/org/springframework/web/filter/ForwardedHeaderFilterTests.java
+++ b/spring-web/src/test/java/org/springframework/web/filter/ForwardedHeaderFilterTests.java
@@ -170,6 +170,43 @@ public class ForwardedHeaderFilterTests {
 		assertEquals("bar", actual.getHeader("foo"));
 	}
 
+	@Test
+	public void requestUriWithForwardedPrefix() throws Exception {
+		this.request.addHeader("X-Forwarded-Prefix", "/prefix");
+		this.request.setRequestURI("/mvc-showcase");
+
+		HttpServletRequest actual = filterAndGetWrappedRequest();
+		assertEquals("http://localhost/prefix/mvc-showcase", actual.getRequestURL()
+				.toString());
+	}
+
+	@Test
+	public void requestUriWithForwardedPrefixTrailingSlash() throws Exception {
+		this.request.addHeader("X-Forwarded-Prefix", "/prefix/");
+		this.request.setRequestURI("/mvc-showcase");
+
+		HttpServletRequest actual = filterAndGetWrappedRequest();
+		assertEquals("http://localhost/prefix/mvc-showcase", actual.getRequestURL()
+				.toString());
+	}
+
+	@Test
+	public void contextPathWithForwardedPrefix() throws Exception {
+		this.request.addHeader("X-Forwarded-Prefix", "/prefix");
+		this.request.setContextPath("/mvc-showcase");
+
+		String actual = filterAndGetContextPath();
+		assertEquals("/prefix/mvc-showcase", actual);
+	}
+
+	@Test
+	public void contextPathWithForwardedPrefixTrailingSlash() throws Exception {
+		this.request.addHeader("X-Forwarded-Prefix", "/prefix/");
+		this.request.setContextPath("/mvc-showcase");
+
+		String actual = filterAndGetContextPath();
+		assertEquals("/prefix/mvc-showcase", actual);
+	}
 
 	private String filterAndGetContextPath() throws ServletException, IOException {
 		return filterAndGetWrappedRequest().getContextPath();