Replaces rather than prepend contextPath

Issue: SPR-16650

Author: rstoyanchev

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

@@ -81,10 +81,15 @@ protected ServletUriComponentsBuilder(ServletUriComponentsBuilder other) {
 	 *
 	 * <p><strong>Note:</strong> This method extracts values from "Forwarded"
 	 * and "X-Forwarded-*" headers if found. See class-level docs.
+	 *
+	 * <p>As of 4.3.15, this method replaces the contextPath with the value
+	 * of "X-Forwarded-Prefix" rather than prepending, thus aligning with
+	 * {@code ForwardedHeaderFiller}.
 	 */
 	public static ServletUriComponentsBuilder fromContextPath(HttpServletRequest request) {
 		ServletUriComponentsBuilder builder = initFromRequest(request);
-		builder.replacePath(prependForwardedPrefix(request, request.getContextPath()));
+		String forwardedPrefix = getForwardedPrefix(request);
+		builder.replacePath(forwardedPrefix != null ? forwardedPrefix : request.getContextPath());
 		return builder;
 	}
 
@@ -98,6 +103,10 @@ public static ServletUriComponentsBuilder fromContextPath(HttpServletRequest req
 	 *
 	 * <p><strong>Note:</strong> This method extracts values from "Forwarded"
 	 * and "X-Forwarded-*" headers if found. See class-level docs.
+	 *
+	 * <p>As of 4.3.15, this method replaces the contextPath with the value
+	 * of "X-Forwarded-Prefix" rather than prepending, thus aligning with
+	 * {@code ForwardedHeaderFiller}.
 	 */
 	public static ServletUriComponentsBuilder fromServletMapping(HttpServletRequest request) {
 		ServletUriComponentsBuilder builder = fromContextPath(request);
@@ -113,10 +122,14 @@ public static ServletUriComponentsBuilder fromServletMapping(HttpServletRequest
 	 *
 	 * <p><strong>Note:</strong> This method extracts values from "Forwarded"
 	 * and "X-Forwarded-*" headers if found. See class-level docs.
+	 *
+	 * <p>As of 4.3.15, this method replaces the contextPath with the value
+	 * of "X-Forwarded-Prefix" rather than prepending, thus aligning with
+	 * {@code ForwardedHeaderFiller}.
 	 */
 	public static ServletUriComponentsBuilder fromRequestUri(HttpServletRequest request) {
 		ServletUriComponentsBuilder builder = initFromRequest(request);
-		builder.initPath(prependForwardedPrefix(request, request.getRequestURI()));
+		builder.initPath(getRequestUriWithForwardedPrefix(request));
 		return builder;
 	}
 
@@ -126,10 +139,14 @@ public static ServletUriComponentsBuilder fromRequestUri(HttpServletRequest requ
 	 *
 	 * <p><strong>Note:</strong> This method extracts values from "Forwarded"
 	 * and "X-Forwarded-*" headers if found. See class-level docs.
+	 *
+	 * <p>As of 4.3.15, this method replaces the contextPath with the value
+	 * of "X-Forwarded-Prefix" rather than prepending, thus aligning with
+	 * {@code ForwardedHeaderFiller}.
 	 */
 	public static ServletUriComponentsBuilder fromRequest(HttpServletRequest request) {
 		ServletUriComponentsBuilder builder = initFromRequest(request);
-		builder.initPath(prependForwardedPrefix(request, request.getRequestURI()));
+		builder.initPath(getRequestUriWithForwardedPrefix(request));
 		builder.query(request.getQueryString());
 		return builder;
 	}
@@ -153,7 +170,7 @@ private static ServletUriComponentsBuilder initFromRequest(HttpServletRequest re
 		return builder;
 	}
 
-	private static String prependForwardedPrefix(HttpServletRequest request, String path) {
+	private static String getForwardedPrefix(HttpServletRequest request) {
 		String prefix = null;
 		Enumeration<String> names = request.getHeaderNames();
 		while (names.hasMoreElements()) {
@@ -163,7 +180,22 @@ private static String prependForwardedPrefix(HttpServletRequest request, String
 			}
 		}
 		if (prefix != null) {
-			path = prefix + path;
+			while (prefix.endsWith("/")) {
+				prefix = prefix.substring(0, prefix.length() - 1);
+			}
+		}
+		return prefix;
+	}
+
+	private static String getRequestUriWithForwardedPrefix(HttpServletRequest request) {
+		String path = request.getRequestURI();
+		String forwardedPrefix = getForwardedPrefix(request);
+		if (forwardedPrefix != null) {
+			String contextPath = request.getContextPath();
+			if (!StringUtils.isEmpty(contextPath) && !contextPath.equals("/") && path.startsWith(contextPath)) {
+				path = path.substring(contextPath.length());
+			}
+			path = forwardedPrefix + path;
 		}
 		return path;
 	}
@@ -177,6 +209,10 @@ private static String prependForwardedPrefix(HttpServletRequest request, String
 	 *
 	 * <p><strong>Note:</strong> This method extracts values from "Forwarded"
 	 * and "X-Forwarded-*" headers if found. See class-level docs.
+	 *
+	 * <p>As of 4.3.15, this method replaces the contextPath with the value
+	 * of "X-Forwarded-Prefix" rather than prepending, thus aligning with
+	 * {@code ForwardedHeaderFiller}.
 	 */
 	public static ServletUriComponentsBuilder fromCurrentContextPath() {
 		return fromContextPath(getCurrentRequest());
@@ -199,6 +235,10 @@ public static ServletUriComponentsBuilder fromCurrentServletMapping() {
 	 *
 	 * <p><strong>Note:</strong> This method extracts values from "Forwarded"
 	 * and "X-Forwarded-*" headers if found. See class-level docs.
+	 *
+	 * <p>As of 4.3.15, this method replaces the contextPath with the value
+	 * of "X-Forwarded-Prefix" rather than prepending, thus aligning with
+	 * {@code ForwardedHeaderFiller}.
 	 */
 	public static ServletUriComponentsBuilder fromCurrentRequestUri() {
 		return fromRequestUri(getCurrentRequest());
@@ -210,6 +250,10 @@ public static ServletUriComponentsBuilder fromCurrentRequestUri() {
 	 *
 	 * <p><strong>Note:</strong> This method extracts values from "Forwarded"
 	 * and "X-Forwarded-*" headers if found. See class-level docs.
+	 *
+	 * <p>As of 4.3.15, this method replaces the contextPath with the value
+	 * of "X-Forwarded-Prefix" rather than prepending, thus aligning with
+	 * {@code ForwardedHeaderFiller}.
 	 */
 	public static ServletUriComponentsBuilder fromCurrentRequest() {
 		return fromRequest(getCurrentRequest());

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

@@ -102,22 +102,33 @@ public void fromRequestUri() {
 		assertEquals("http://localhost/mvc-showcase/data/param", result);
 	}
 
-	@Test
+	@Test // SPR-16650
 	public void fromRequestWithForwardedPrefix() {
-		this.request.setRequestURI("/bar");
-		this.request.addHeader("X-Forwarded-Prefix", "/foo");
+		this.request.addHeader("X-Forwarded-Prefix", "/prefix");
+		this.request.setContextPath("/mvc-showcase");
+		this.request.setRequestURI("/mvc-showcase/bar");
 		UriComponents result = ServletUriComponentsBuilder.fromRequest(this.request).build();
-		assertEquals("http://localhost/foo/bar", result.toUriString());
+		assertEquals("http://localhost/prefix/bar", result.toUriString());
 	}
 
-	@Test
+	@Test // SPR-16650
 	public void fromRequestWithForwardedPrefixTrailingSlash() {
-		this.request.setRequestURI("/bar");
 		this.request.addHeader("X-Forwarded-Prefix", "/foo/");
+		this.request.setContextPath("/spring-mvc-showcase");
+		this.request.setRequestURI("/spring-mvc-showcase/bar");
 		UriComponents result = ServletUriComponentsBuilder.fromRequest(this.request).build();
 		assertEquals("http://localhost/foo/bar", result.toUriString());
 	}
 
+	@Test // SPR-16650
+	public void fromRequestWithForwardedPrefixRoot() {
+		this.request.addHeader("X-Forwarded-Prefix", "/");
+		this.request.setContextPath("/mvc-showcase");
+		this.request.setRequestURI("/mvc-showcase/bar");
+		UriComponents result = ServletUriComponentsBuilder.fromRequest(this.request).build();
+		assertEquals("http://localhost/bar", result.toUriString());
+	}
+
 	@Test
 	public void fromContextPath() {
 		this.request.setRequestURI("/mvc-showcase/data/param");
@@ -126,13 +137,13 @@ public void fromContextPath() {
 		assertEquals("http://localhost/mvc-showcase", result);
 	}
 
-	@Test
+	@Test // SPR-16650
 	public void fromContextPathWithForwardedPrefix() {
 		this.request.addHeader("X-Forwarded-Prefix", "/prefix");
 		this.request.setContextPath("/mvc-showcase");
 		this.request.setRequestURI("/mvc-showcase/simple");
 		String result = ServletUriComponentsBuilder.fromContextPath(this.request).build().toUriString();
-		assertEquals("http://localhost/prefix/mvc-showcase", result);
+		assertEquals("http://localhost/prefix", result);
 	}
 
 	@Test
@@ -144,14 +155,14 @@ public void fromServletMapping() {
 		assertEquals("http://localhost/mvc-showcase/app", result);
 	}
 
-	@Test
+	@Test // SPR-16650
 	public void fromServletMappingWithForwardedPrefix() {
 		this.request.addHeader("X-Forwarded-Prefix", "/prefix");
 		this.request.setContextPath("/mvc-showcase");
 		this.request.setServletPath("/app");
 		this.request.setRequestURI("/mvc-showcase/app/simple");
 		String result = ServletUriComponentsBuilder.fromServletMapping(this.request).build().toUriString();
-		assertEquals("http://localhost/prefix/mvc-showcase/app", result);
+		assertEquals("http://localhost/prefix/app", result);
 	}
 
 	@Test
@@ -168,9 +179,7 @@ public void fromCurrentRequest() {
 		}
 	}
 
-	// SPR-10272
-
-	@Test
+	@Test // SPR-10272
 	public void pathExtension() {
 		this.request.setRequestURI("/rest/books/6.json");
 		ServletUriComponentsBuilder builder = ServletUriComponentsBuilder.fromRequestUri(this.request);