Adds BeforeFilterFunctions.mapRequestHeader()

See gh-2949

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

@@ -19,6 +19,7 @@ package org.springframework.cloud.gateway.server.mvc.filter;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
 import java.util.regex.Pattern;
@@ -70,6 +71,16 @@ public abstract class BeforeFilterFunctions {
 		};
 	}
 
+	public static Function<ServerRequest, ServerRequest> mapRequestHeader(String fromHeader, String toHeader) {
+		return request -> {
+			if (request.headers().asHttpHeaders().containsKey(fromHeader)) {
+				List<String> values = request.headers().header(fromHeader);
+				return ServerRequest.from(request).header(toHeader, values.toArray(new String[0])).build();
+			}
+			return request;
+		};
+	}
+
 	public static Function<ServerRequest, ServerRequest> prefixPath(String prefix) {
 		final UriTemplate uriTemplate = new UriTemplate(prefix);
 

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

@@ -50,6 +50,11 @@ public interface FilterFunctions {
 		return ofResponseProcessor(AfterFilterFunctions.addResponseHeader(name, values));
 	}
 
+	@Shortcut
+	static HandlerFilterFunction<ServerResponse, ServerResponse> mapRequestHeader(String fromHeader, String toHeader) {
+		return ofRequestProcessor(BeforeFilterFunctions.mapRequestHeader(fromHeader, toHeader));
+	}
+
 	@Shortcut
 	static HandlerFilterFunction<ServerResponse, ServerResponse> prefixPath(String prefix) {
 		return ofRequestProcessor(BeforeFilterFunctions.prefixPath(prefix));

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

@@ -74,6 +74,7 @@ import static org.springframework.cloud.gateway.server.mvc.filter.AfterFilterFun
 import static org.springframework.cloud.gateway.server.mvc.filter.AfterFilterFunctions.rewriteResponseHeader;
 import static org.springframework.cloud.gateway.server.mvc.filter.AfterFilterFunctions.setResponseHeader;
 import static org.springframework.cloud.gateway.server.mvc.filter.AfterFilterFunctions.setStatus;
+import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.mapRequestHeader;
 import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.preserveHost;
 import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.removeRequestParameter;
 import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.requestHeaderSize;
@@ -465,6 +466,15 @@ public class ServerMvcIntegrationTests {
 				.exchange().expectStatus().isOk().expectBody(String.class).isEqualTo("Hello");
 	}
 
+	@Test
+	public void mapRequestHeaderWorks() {
+		restClient.get().uri("/anything/maprequestheader").header("X-Foo", "fooval").exchange().expectStatus().isOk()
+				.expectBody(Map.class).consumeWith(res -> {
+					Map<String, Object> headers = getMap(res.getResponseBody(), "headers");
+					assertThat(headers).containsEntry("X-Bar", "fooval");
+				});
+	}
+
 	@SpringBootConfiguration
 	@EnableAutoConfiguration
 	@LoadBalancerClient(name = "httpbin", configuration = TestLoadBalancerConfig.Httpbin.class)
@@ -833,6 +843,17 @@ public class ServerMvcIntegrationTests {
 			// @formatter:on
 		}
 
+		@Bean
+		public RouterFunction<ServerResponse> gatewayRouterFunctionsMapRequestHeader() {
+			// @formatter:off
+			return route("testmaprequestheader")
+					.GET("/anything/maprequestheader", http())
+					.before(new HttpbinUriResolver())
+					.before(mapRequestHeader("X-Foo", "X-Bar"))
+					.build();
+			// @formatter:on
+		}
+
 	}
 
 	@RestController