Also apply X-Forwarded-Prefix in fromContextPath

Issue: SPR-12500

Author: rstoyanchev

spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java

@@ -28,7 +28,7 @@
 import org.springframework.web.util.WebUtils;
 
 /**
- * A UriComponentsBuilder that extracts information from an HttpServletRequest.
+ * A UriComponentsBuilder that extracts information from the HttpServletRequest.
  *
  * @author Rossen Stoyanchev
  * @since 3.1
@@ -56,8 +56,10 @@ protected ServletUriComponentsBuilder() {
 	 * an HttpServletRequest.
 	 */
 	public static ServletUriComponentsBuilder fromContextPath(HttpServletRequest request) {
+		String path = request.getContextPath();
+		path = prependForwardedPrefix(request, path);
 		ServletUriComponentsBuilder builder = fromRequest(request);
-		builder.replacePath(request.getContextPath());
+		builder.replacePath(path);
 		builder.replaceQuery(null);
 		return builder;
 	}
@@ -98,7 +100,6 @@ public static ServletUriComponentsBuilder fromRequest(HttpServletRequest request
 		String scheme = request.getScheme();
 		String host = request.getServerName();
 		int port = request.getServerPort();
-		String path = request.getRequestURI();
 
 		String hostHeader = request.getHeader("X-Forwarded-Host");
 		if (StringUtils.hasText(hostHeader)) {
@@ -125,10 +126,8 @@ public static ServletUriComponentsBuilder fromRequest(HttpServletRequest request
 			scheme = protocolHeader;
 		}
 
-		String prefix = request.getHeader("X-Forwarded-Prefix");
-		if (StringUtils.hasText(prefix)) {
-			path = prefix + path;
-		}
+		String path = request.getRequestURI();
+		path = prependForwardedPrefix(request, path);
 
 		ServletUriComponentsBuilder builder = new ServletUriComponentsBuilder();
 		builder.scheme(scheme);
@@ -141,6 +140,14 @@ public static ServletUriComponentsBuilder fromRequest(HttpServletRequest request
 		return builder;
 	}
 
+	private static String prependForwardedPrefix(HttpServletRequest request, String path) {
+		String prefix = request.getHeader("X-Forwarded-Prefix");
+		if (StringUtils.hasText(prefix)) {
+			path = prefix + path;
+		}
+		return path;
+	}
+
 	/**
 	 * Same as {@link #fromContextPath(HttpServletRequest)} except the
 	 * request is obtained through {@link RequestContextHolder}.

spring-webmvc/src/test/java/org/springframework/web/servlet/support/ServletUriComponentsBuilderTests.java

@@ -176,6 +176,15 @@ public void fromContextPath() {
 		assertEquals("http://localhost/mvc-showcase", result);
 	}
 
+	@Test
+	public void fromContextPathWithForwardedPrefix() {
+		request.addHeader("X-Forwarded-Prefix", "/prefix");
+		request.setContextPath("/mvc-showcase");
+		request.setRequestURI("/mvc-showcase/simple");
+		String result = ServletUriComponentsBuilder.fromContextPath(request).build().toUriString();
+		assertEquals("http://localhost/prefix/mvc-showcase", result);
+	}
+
 	@Test
 	public void fromServletMapping() {
 		request.setRequestURI("/mvc-showcase/app/simple");
@@ -185,6 +194,16 @@ public void fromServletMapping() {
 		assertEquals("http://localhost/mvc-showcase/app", result);
 	}
 
+	@Test
+	public void fromServletMappingWithForwardedPrefix() {
+		request.addHeader("X-Forwarded-Prefix", "/prefix");
+		request.setContextPath("/mvc-showcase");
+		request.setServletPath("/app");
+		request.setRequestURI("/mvc-showcase/app/simple");
+		String result = ServletUriComponentsBuilder.fromServletMapping(request).build().toUriString();
+		assertEquals("http://localhost/prefix/mvc-showcase/app", result);
+	}
+
 	@Test
 	public void fromCurrentRequest() {
 		request.setRequestURI("/mvc-showcase/data/param");