Handle X-Forwarded-Prefix parsed by Reactor Netty

See gh-33638

framework-platform/framework-platform.gradle

@@ -11,7 +11,7 @@ dependencies {
 	api(platform("io.micrometer:micrometer-bom:1.14.0-M3"))
 	api(platform("io.netty:netty-bom:4.1.113.Final"))
 	api(platform("io.netty:netty5-bom:5.0.0.Alpha5"))
-	api(platform("io.projectreactor:reactor-bom:2024.0.0-M6"))
+	api(platform("io.projectreactor:reactor-bom:2024.0.0-SNAPSHOT"))
 	api(platform("io.rsocket:rsocket-bom:1.1.3"))
 	api(platform("org.apache.groovy:groovy-bom:4.0.23"))
 	api(platform("org.apache.logging.log4j:log4j-bom:2.21.1"))
@@ -50,6 +50,7 @@ dependencies {
 		api("io.micrometer:context-propagation:1.1.1")
 		api("io.mockk:mockk:1.13.4")
 		api("io.projectreactor.netty:reactor-netty5-http:2.0.0-M3")
+		api("io.projectreactor.netty:reactor-netty-http")
 		api("io.projectreactor.tools:blockhound:1.0.8.RELEASE")
 		api("io.r2dbc:r2dbc-h2:1.0.0.RELEASE")
 		api("io.r2dbc:r2dbc-spi-test:1.0.0.RELEASE")

spring-web/src/main/java/org/springframework/http/server/reactive/ReactorServerHttpRequest.java

@@ -65,7 +65,8 @@ class ReactorServerHttpRequest extends AbstractServerHttpRequest {
 	public ReactorServerHttpRequest(HttpServerRequest request, NettyDataBufferFactory bufferFactory)
 			throws URISyntaxException {
 
-		super(HttpMethod.valueOf(request.method().name()), ReactorUriHelper.createUri(request), "",
+		super(HttpMethod.valueOf(request.method().name()),
+				ReactorUriHelper.createUri(request), request.forwardedPrefix(),
 				new Netty4HeadersAdapter(request.requestHeaders()));
 		Assert.notNull(bufferFactory, "DataBufferFactory must not be null");
 		this.request = request;

spring-web/src/main/java/org/springframework/http/server/reactive/ReactorUriHelper.java

@@ -48,8 +48,12 @@ abstract class ReactorUriHelper {
 			builder.append(port);
 		}
 
-		appendRequestUri(request, builder);
+		String prefix = request.forwardedPrefix();
+		if (prefix != null && !prefix.isEmpty()) {
+			builder.append(prefix);
+		}
 
+		appendRequestUri(request, builder);
 		return new URI(builder.toString());
 	}
 

spring-web/src/test/java/org/springframework/http/server/reactive/ReactorUriHelperTests.java

@@ -20,6 +20,8 @@ import java.net.URI;
 import java.net.URISyntaxException;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 import reactor.netty.http.server.HttpServerRequest;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -49,4 +51,29 @@ class ReactorUriHelperTests {
 
 	}
 
+	@ParameterizedTest(name = "{displayName}({arguments})")
+	@CsvSource(delimiter='|', value = {
+			"/prefix           | /prefix/",
+			"/prefix1/prefix2  | /prefix1/prefix2/",
+			"                  | /",
+			"''                | /",
+	})
+	void forwardedPrefix(String prefixHeader, String expectedPath) throws URISyntaxException {
+		HttpServerRequest nettyRequest = mock();
+
+		given(nettyRequest.scheme()).willReturn("https");
+		given(nettyRequest.hostName()).willReturn("localhost");
+		given(nettyRequest.hostPort()).willReturn(443);
+		given(nettyRequest.uri()).willReturn("/");
+		given(nettyRequest.forwardedPrefix()).willReturn(prefixHeader);
+
+		URI uri = ReactorUriHelper.createUri(nettyRequest);
+		assertThat(uri).hasScheme("https")
+				.hasHost("localhost")
+				.hasPort(-1)
+				.hasPath(expectedPath)
+				.hasToString("https://localhost" + expectedPath);
+	}
+
+
 }