Adds RequestSizeFilter

Request Size Limit filter with test case and review comments

docs/src/main/asciidoc/spring-cloud-gateway.adoc

@@ -775,6 +775,32 @@ spring:
 
 NOTE: At this time a URI using the `forward` protocol does not support using the retry filter.
 
+=== RequestSize GatewayFilter Factory
+The RequestSize GatewayFilter Factory can restrict a request from reaching the downstream service , when the request size is greater than the permissible limit. The filter takes `RequestSize` as parameter which is the permissible size limit of the request defined in bytes.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: request_size_route
+      uri: http://localhost:8080/upload
+      predicates:
+      - Path=/upload
+      filters:
+      - name: RequestSize
+        args:
+          maxSize: 5000000
+----
+
+The RequestSize GatewayFilter Factory set the response status as `413 Payload Too Large` with a additional header `errorMessage` when the Request is rejected due to size. Following is an example of such an `errorMessage` .
+
+`errorMessage` : `Request size is larger than permissible limit. Request size is 6.0 MB where permissible limit is 5.0 MB`
+
+NOTE: The default Request size will be set to 5 MB if not provided as filter argument in route definition.
+
 == Global Filters
 
 The `GlobalFilter` interface has the same signature as `GatewayFilter`. These are special filters that are conditionally applied to all routes. (This interface and usage are subject to change in future milestones).

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@@ -64,6 +64,7 @@ import org.springframework.cloud.gateway.filter.factory.RemoveRequestHeaderGatew
 import org.springframework.cloud.gateway.filter.factory.RemoveResponseHeaderGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RequestHeaderToRequestUriGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RequestRateLimiterGatewayFilterFactory;
+import org.springframework.cloud.gateway.filter.factory.RequestSizeGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RetryGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.SaveSessionGatewayFilterFactory;
@@ -574,6 +575,11 @@ public class GatewayAutoConfiguration {
 	public RequestHeaderToRequestUriGatewayFilterFactory requestHeaderToRequestUriGatewayFilterFactory() {
 		return new RequestHeaderToRequestUriGatewayFilterFactory();
 	}
+	
+	@Bean
+	public RequestSizeGatewayFilterFactory requestSizeGatewayFilterFactory() {
+		return new RequestSizeGatewayFilterFactory();
+	}
 
 	@Configuration
 	@ConditionalOnClass(Health.class)

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/RequestSizeGatewayFilterFactory.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2013-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.springframework.cloud.gateway.filter.factory;
+
+import org.springframework.cloud.gateway.filter.GatewayFilter;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * This filter blocks the request, if the request size is more than the permissible size.The default request size is 5 MB.
+ * @author Arpan
+ */
+public class RequestSizeGatewayFilterFactory
+		extends AbstractGatewayFilterFactory<RequestSizeGatewayFilterFactory.RequestSizeConfig> {
+
+	private static String PREFIX = "kMGTPE";
+	private static String ERROR = "Request size is larger than permissible limit."
+			+ " Request size is %s where permissible limit is %s";
+
+	public RequestSizeGatewayFilterFactory() {
+		super(RequestSizeGatewayFilterFactory.RequestSizeConfig.class);
+	}
+
+	@Override
+	public GatewayFilter apply(RequestSizeGatewayFilterFactory.RequestSizeConfig requestSizeConfig) {
+		requestSizeConfig.validate();
+		return (exchange, chain) -> {
+			ServerHttpRequest request = exchange.getRequest();
+			String contentLength = request.getHeaders().getFirst("content-length");
+			if (!StringUtils.isEmpty(contentLength)) {
+				Long currentRequestSize = Long.valueOf(contentLength);
+				if (currentRequestSize > requestSizeConfig.getMaxSize()) {
+					exchange.getResponse().setStatusCode(HttpStatus.PAYLOAD_TOO_LARGE);
+					exchange.getResponse().getHeaders().add("errorMessage",
+							getErrorMessage(currentRequestSize, requestSizeConfig.getMaxSize()));
+					return exchange.getResponse().setComplete();
+				}
+			}
+			return chain.filter(exchange);
+		};
+	}
+
+	public static class RequestSizeConfig {
+
+		private Long maxSize = 5000000L;
+
+		public RequestSizeGatewayFilterFactory.RequestSizeConfig setMaxSize(Long maxSize) {
+			this.maxSize = maxSize;
+			return this;
+		}
+
+		public Long getMaxSize() {
+			return maxSize;
+		}
+
+		public void validate() {
+			Assert.isTrue(this.maxSize != null && this.maxSize > 0, "maxSize must be greater than 0");
+			Assert.isInstanceOf(Long.class, maxSize, "maxSize must be a number");
+		}
+	}
+
+	private static String getErrorMessage(Long currentRequestSize, Long maxSize) {
+		return String.format(ERROR, getReadableByteCount(currentRequestSize), getReadableByteCount(maxSize));
+	}
+
+	private static String getReadableByteCount(long bytes) {
+		int unit = 1000;
+		if (bytes < unit)
+			return bytes + " B";
+		int exp = (int) (Math.log(bytes) / Math.log(unit));
+		String pre = Character.toString(PREFIX.charAt(exp - 1));
+		return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
+	}
+}

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/route/builder/GatewayFilterSpec.java

@@ -47,6 +47,7 @@ import org.springframework.cloud.gateway.filter.factory.RemoveRequestHeaderGatew
 import org.springframework.cloud.gateway.filter.factory.RemoveResponseHeaderGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RequestHeaderToRequestUriGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RequestRateLimiterGatewayFilterFactory;
+import org.springframework.cloud.gateway.filter.factory.RequestSizeGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RetryGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.SaveSessionGatewayFilterFactory;
@@ -555,6 +556,16 @@ public class GatewayFilterSpec extends UriSpec {
 				}.apply(c -> {
 				}));
 	}
+	
+
+	/**
+	 * A filter that sets the maximum permissible size of a Request.
+	 * @param size the maximum size of a request
+	 * @return a {@link GatewayFilterSpec} that can be used to apply additional filters
+	 */
+	public GatewayFilterSpec setRequestSize(Long size) {
+		return filter(getBean(RequestSizeGatewayFilterFactory.class).apply(c -> c.setMaxSize(size)));
+	}
 
 	private String routeId() {
 		return routeBuilder.getId();

spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/filter/factory/RequestSizeGatewayFilterFactoryTest.java

@@ -0,0 +1,54 @@
+package org.springframework.cloud.gateway.filter.factory;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.gateway.route.RouteLocator;
+import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
+import org.springframework.cloud.gateway.test.BaseWebClientTests;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.HttpStatus;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
+
+/**
+ * @author Arpan Das
+ */
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@DirtiesContext
+public class RequestSizeGatewayFilterFactoryTest extends BaseWebClientTests {
+	
+	private static final String responseMesssage = "Request size is larger than permissible limit. Request size is 6.0 MB where permissible limit is 5.0 MB";
+
+	@Test
+	public void setRequestSizeFilterWorks() {
+		testClient.get().uri("/headers")
+				.header("Host", "www.setrequestsize.org")
+				.header("content-length", "6000000")
+				.exchange().expectStatus().isEqualTo(HttpStatus.PAYLOAD_TOO_LARGE)
+				.expectHeader().valueMatches("errorMessage", responseMesssage);
+	}
+
+	@EnableAutoConfiguration
+	@SpringBootConfiguration
+	@Import(DefaultTestConfig.class)
+	public static class TestConfig {
+		@Value("${test.uri}")
+		String uri;
+
+		@Bean
+		public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
+			return builder.routes().route("test_request_size",
+					r -> r.order(-1).host("**.setrequestsize.org").filters(f -> f.setRequestSize(5000000L)).uri(uri))
+					.build();
+		}
+	}
+}