Adds support for saving original request URL to request attributes

This enables X-Forwarded-Prefix.

Fixes gh-3354
Fixes gh-3443

Author: jrhenderson1988

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/common/MvcUtils.java

@@ -25,6 +25,7 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -72,6 +73,11 @@ public abstract class MvcUtils {
 	 */
 	public static final String GATEWAY_ATTRIBUTES_ATTR = qualify("gatewayAttributes");
 
+	/**
+	 * Gateway original request URL attribute name.
+	 */
+	public static final String GATEWAY_ORIGINAL_REQUEST_URL_ATTR = qualify("gatewayOriginalRequestUrl");
+
 	/**
 	 * Gateway request URL attribute name.
 	 */
@@ -250,6 +256,15 @@ public static void setRequestUrl(ServerRequest request, URI url) {
 		request.servletRequest().setAttribute(GATEWAY_REQUEST_URL_ATTR, url);
 	}
 
+	public static void addOriginalRequestUrl(ServerRequest request, URI url) {
+		LinkedHashSet<URI> urls = getAttribute(request, GATEWAY_ORIGINAL_REQUEST_URL_ATTR);
+		if (urls == null) {
+			urls = new LinkedHashSet<>();
+		}
+		urls.add(url);
+		putAttribute(request, GATEWAY_ORIGINAL_REQUEST_URL_ATTR, urls);
+	}
+
 	private record ByteArrayInputMessage(ServerRequest request, ByteArrayInputStream body) implements HttpInputMessage {
 
 		@Override

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/BeforeFilterFunctions.java

@@ -389,6 +389,7 @@ public static Function<ServerRequest, ServerRequest> stripPrefix() {
 
 	public static Function<ServerRequest, ServerRequest> stripPrefix(int parts) {
 		return request -> {
+			MvcUtils.addOriginalRequestUrl(request, request.uri());
 			// TODO: gateway url attributes
 			String path = request.uri().getRawPath();
 			// TODO: begin duplicate code from StripPrefixGatewayFilterFactory
@@ -414,6 +415,8 @@ public static Function<ServerRequest, ServerRequest> stripPrefix(int parts) {
 				.replacePath(newPath.toString())
 				.build(true)
 				.toUri();
+			MvcUtils.setRequestUrl(request, prefixedUri);
+
 			return ServerRequest.from(request).uri(prefixedUri).build();
 		};
 	}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/XForwardedRequestHeadersFilter.java

@@ -25,6 +25,7 @@
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.DeprecatedConfigurationProperty;
 import org.springframework.boot.context.properties.PropertyMapper;
+import org.springframework.cloud.gateway.server.mvc.common.MvcUtils;
 import org.springframework.core.Ordered;
 import org.springframework.http.HttpHeaders;
 import org.springframework.util.ObjectUtils;
@@ -397,18 +398,15 @@ public HttpHeaders apply(HttpHeaders input, ServerRequest request) {
 			// - see XForwardedHeadersFilterTests, so first get uris, then extract paths
 			// and remove one from another if it's the ending part.
 
-			LinkedHashSet<URI> originalUris = null; // TODO:
-													// exchange.getAttribute(GATEWAY_ORIGINAL_REQUEST_URL_ATTR);
-			URI requestUri = null; // TODO:
-									// exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR);
+			LinkedHashSet<URI> originalUris = MvcUtils.getAttribute(request,
+					MvcUtils.GATEWAY_ORIGINAL_REQUEST_URL_ATTR);
+			URI requestUri = MvcUtils.getAttribute(request, MvcUtils.GATEWAY_REQUEST_URL_ATTR);
 
 			if (originalUris != null && requestUri != null) {
 
 				originalUris.forEach(originalUri -> {
 
 					if (originalUri != null && originalUri.getPath() != null) {
-						String prefix = originalUri.getPath();
-
 						// strip trailing slashes before checking if request path is end
 						// of original path
 						String originalUriPath = stripTrailingSlash(originalUri);

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/ServerMvcIntegrationTests.java

@@ -242,6 +242,14 @@ public void stripPrefixWorks() {
 			.consumeWith(res -> {
 				Map<String, Object> map = res.getResponseBody();
 				Map<String, Object> headers = getMap(map, "headers");
+				assertThat(headers).containsKeys(
+						XForwardedRequestHeadersFilter.X_FORWARDED_PREFIX_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_HOST_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_PORT_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_PROTO_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_FOR_HEADER);
+				assertThat(headers).containsEntry(
+						XForwardedRequestHeadersFilter.X_FORWARDED_PREFIX_HEADER, "/long/path/to");
 				assertThat(headers).containsEntry("X-Test", "stripPrefix");
 			});
 	}
@@ -260,6 +268,14 @@ public void stripPrefixPostWorks() {
 				Map<String, Object> map = res.getResponseBody();
 				assertThat(map).containsEntry("data", "hello");
 				Map<String, Object> headers = getMap(map, "headers");
+				assertThat(headers).containsKeys(
+						XForwardedRequestHeadersFilter.X_FORWARDED_PREFIX_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_HOST_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_PORT_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_PROTO_HEADER,
+						XForwardedRequestHeadersFilter.X_FORWARDED_FOR_HEADER);
+				assertThat(headers).containsEntry(
+						XForwardedRequestHeadersFilter.X_FORWARDED_PREFIX_HEADER, "/long/path/to");
 				assertThat(headers).containsEntry("X-Test", "stripPrefixPost");
 			});
 	}
@@ -1068,9 +1084,9 @@ public RouterFunction<ServerResponse> gatewayRouterFunctionsSetPathPost() {
 		public RouterFunction<ServerResponse> gatewayRouterFunctionsStripPrefix() {
 			// @formatter:off
 			return route(GET("/long/path/to/get"), http())
-					.filter(new HttpbinUriResolver())
 					.filter(stripPrefix(3))
 					.filter(addRequestHeader("X-Test", "stripPrefix"))
+					.filter(new HttpbinUriResolver(true))
 					.withAttribute(MvcUtils.GATEWAY_ROUTE_ID_ATTR, "teststripprefix");
 			// @formatter:on
 		}
@@ -1080,9 +1096,9 @@ public RouterFunction<ServerResponse> gatewayRouterFunctionsStripPrefixPost() {
 			// @formatter:off
 			return route("teststripprefixpost")
 					.route(POST("/long/path/to/post").and(host("**.stripprefixpost.org")), http())
-					.filter(new HttpbinUriResolver())
 					.filter(stripPrefix(3))
 					.filter(addRequestHeader("X-Test", "stripPrefixPost"))
+					.filter(new HttpbinUriResolver(true))
 					.build();
 			// @formatter:on
 		}

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/test/HttpbinUriResolver.java

@@ -17,6 +17,7 @@
 package org.springframework.cloud.gateway.server.mvc.test;
 
 import java.net.URI;
+import java.net.URISyntaxException;
 import java.util.function.Function;
 
 import org.springframework.cloud.gateway.server.mvc.common.MvcUtils;
@@ -30,12 +31,32 @@
 public class HttpbinUriResolver
 		implements Function<ServerRequest, ServerRequest>, HandlerFilterFunction<ServerResponse, ServerResponse> {
 
+	private final boolean preservePath;
+
+	public HttpbinUriResolver(boolean preservePath) {
+		this.preservePath = preservePath;
+	}
+
+	public HttpbinUriResolver() {
+		this(false);
+	}
+
 	protected URI uri(ServerRequest request) {
 		ApplicationContext context = MvcUtils.getApplicationContext(request);
 		Integer port = context.getEnvironment().getProperty("httpbin.port", Integer.class);
 		String host = context.getEnvironment().getProperty("httpbin.host");
 		Assert.hasText(host, "httpbin.host is not set, did you initialize HttpbinTestcontainers?");
 		Assert.notNull(port, "httpbin.port is not set, did you initialize HttpbinTestcontainers?");
+		if (preservePath) {
+			URI original = request.uri();
+			try {
+				return new URI("http", original.getUserInfo(), host, port, original.getPath(),
+						original.getQuery(), original.getFragment());
+			} catch (URISyntaxException e) {
+				throw new IllegalArgumentException(e.getMessage(), e);
+			}
+		}
+
 		return URI.create(String.format("http://%s:%d", host, port));
 	}