Fixes RequestHeaderSizeGatewayFilterFactory to check individual headers.

Previously, it checked the aggregate length of all headers.

Fixes gh-2567

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

@@ -1145,8 +1145,8 @@ This will remove the `red` parameter before it is sent downstream.
 
 === `RequestHeaderSize` `GatewayFilter` Factory
 
-The `RequestHeaderSize` `GatewayFilter` factory takes a `maxSize` parameter.
-It is the maximum data size allowed of the request header (incuding key and value).
+The `RequestHeaderSize` `GatewayFilter` factory takes `maxSize` and `errorHeaderName` parameters.
+The `maxSize` parameter is the maximum data size allowed of the request header (incuding key and value). The `errorHeaderName` parameter sets the name of the response header containing an error message, by default it is "errorMessage".
 The following listing configures a `RequestHeaderSize` `GatewayFilter`:
 
 .application.yml

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/RequestHeaderSizeGatewayFilterFactory.java

@@ -17,6 +17,7 @@
 package org.springframework.cloud.gateway.filter.factory;
 
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -45,8 +46,9 @@ import static org.springframework.cloud.gateway.support.GatewayToStringStyler.fi
 public class RequestHeaderSizeGatewayFilterFactory
 		extends AbstractGatewayFilterFactory<RequestHeaderSizeGatewayFilterFactory.Config> {
 
-	private static String ERROR = "Request Header/s size is larger than permissible limit."
-			+ " Request Header/s size is %s where permissible limit is %s";
+	private static String ERROR_PREFIX = "Request Header/s size is larger than permissible limit (%s).";
+
+	private static String ERROR = " Request Header/s size for '%s' is %s.";
 
 	public RequestHeaderSizeGatewayFilterFactory() {
 		super(RequestHeaderSizeGatewayFilterFactory.Config.class);
@@ -59,25 +61,30 @@ public class RequestHeaderSizeGatewayFilterFactory
 
 	@Override
 	public GatewayFilter apply(RequestHeaderSizeGatewayFilterFactory.Config config) {
+		String errorHeaderName = config.getErrorHeaderName() != null ? config.getErrorHeaderName() : "errorMessage";
 		return new GatewayFilter() {
 			@Override
 			public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
 				ServerHttpRequest request = exchange.getRequest();
 				HttpHeaders headers = request.getHeaders();
-				Long headerSizeInBytes = 0L;
+				HashMap<String, Long> longHeaders = new HashMap<>();
 
 				for (Map.Entry<String, List<String>> headerEntry : headers.entrySet()) {
-					headerSizeInBytes += (long) headerEntry.getKey().getBytes().length;
+					long headerSizeInBytes = 0L;
+					headerSizeInBytes += headerEntry.getKey().getBytes().length;
 					List<String> values = headerEntry.getValue();
 					for (String value : values) {
-						headerSizeInBytes += (long) value.getBytes().length;
+						headerSizeInBytes += value.getBytes().length;
+					}
+					if (headerSizeInBytes > config.getMaxSize().toBytes()) {
+						longHeaders.put(headerEntry.getKey(), headerSizeInBytes);
 					}
 				}
 
-				if (headerSizeInBytes > config.getMaxSize().toBytes()) {
+				if (!longHeaders.isEmpty()) {
 					exchange.getResponse().setStatusCode(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE);
-					exchange.getResponse().getHeaders().add("errorMessage",
-							getErrorMessage(headerSizeInBytes, config.getMaxSize()));
+					exchange.getResponse().getHeaders().add(errorHeaderName,
+							getErrorMessage(longHeaders, config.getMaxSize()));
 					return exchange.getResponse().setComplete();
 
 				}
@@ -93,14 +100,19 @@ public class RequestHeaderSizeGatewayFilterFactory
 		};
 	}
 
-	private static String getErrorMessage(Long currentRequestSize, DataSize maxSize) {
-		return String.format(ERROR, DataSize.of(currentRequestSize, DataUnit.BYTES), maxSize);
+	private static String getErrorMessage(HashMap<String, Long> longHeaders, DataSize maxSize) {
+		StringBuilder msg = new StringBuilder(String.format(ERROR_PREFIX, maxSize));
+		longHeaders
+				.forEach((header, size) -> msg.append(String.format(ERROR, header, DataSize.of(size, DataUnit.BYTES))));
+		return msg.toString();
 	}
 
 	public static class Config {
 
 		private DataSize maxSize = DataSize.ofBytes(16000L);
 
+		private String errorHeaderName;
+
 		public DataSize getMaxSize() {
 			return maxSize;
 		}
@@ -109,6 +121,13 @@ public class RequestHeaderSizeGatewayFilterFactory
 			this.maxSize = maxSize;
 		}
 
+		public String getErrorHeaderName() {
+			return errorHeaderName;
+		}
+
+		public void setErrorHeaderName(String errorHeaderName) {
+			this.errorHeaderName = errorHeaderName;
+		}
 	}
 
 }

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/RequestHeaderSizeGatewayFilterFactoryTest.java

@@ -46,31 +46,40 @@ import static org.springframework.boot.test.context.SpringBootTest.WebEnvironmen
 @DirtiesContext
 public class RequestHeaderSizeGatewayFilterFactoryTest extends BaseWebClientTests {
 
-	private static final String responseMesssage = "Request Header/s size is larger than "
-			+ "permissible limit. Request Header/s size is \\d*B where permissible limit is \\d*B";
+	private static final String longString = "11111111112222222222333333333344444444445555555";
 
 	@Test
 	public void setRequestHeaderSizeFilterWorks() {
+		System.err.println("Here: " + longString.length() + ", " + longString.getBytes().length);
 		testClient.get().uri("/headers").header("Host", "www.testrequestheadersizefilter.org")
-				.header("HeaderName", "Some Very Large Header Name").exchange().expectStatus()
-				.isEqualTo(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE).expectHeader()
-				.valueMatches("errorMessage", responseMesssage);
+				.header("HeaderName", longString).exchange().expectStatus()
+				.isEqualTo(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE).expectHeader().value("errorMessage",
+						header -> assertThat(header).contains("permissible limit (46B)", "'HeaderName' is 57B"));
 	}
 
 	@Test
 	public void setRequestHeaderSizeFilterShortcutWorks() {
-		testClient.get().uri("/headers").header("Host", "www.requestheadersize.org")
-				.header("HeaderName", "Some Very Large Header Name").exchange().expectStatus()
+		testClient.get().uri("/headers").header("Host", "www.requestheadersize.org").header("HeaderName", longString)
+				.exchange().expectStatus().isEqualTo(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE).expectHeader()
+				.value("errorMessage",
+						header -> assertThat(header).contains("permissible limit (46B)", "'HeaderName' is 57B"));
+	}
+
+	@Test
+	public void setRequestHeaderSizeFilterMultipleHeadersWorks() {
+		testClient.get().uri("/headers").header("Host", "www.requestheadersize.org").header("HeaderName", longString)
+				.header("HeaderName2", longString).exchange().expectStatus()
 				.isEqualTo(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE).expectHeader()
-				.valueMatches("errorMessage", responseMesssage);
+				.value("errorMessage", header -> assertThat(header).contains("permissible limit (46B)",
+						"'HeaderName' is 57B", "'HeaderName2' is 58B"));
 	}
 
 	@Test
 	public void setRequestHeaderSizeFilterTakesIntoAccountHeaderName() {
-		testClient.get().uri("/headerName").header("Host", "www.testrequestheadersizefiltername.org")
-				.header("HeaderName", "X").exchange().expectStatus()
-				.isEqualTo(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE).expectHeader()
-				.valueMatches("errorMessage", responseMesssage);
+		testClient.get().uri("/headers").header("Host", "www.testrequestheadersizefiltername.org")
+				.header("HeaderName", longString).exchange().expectStatus()
+				.isEqualTo(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE).expectHeader().value("errorMessage",
+						header -> assertThat(header).contains("permissible limit (47B)", "'HeaderName' is 57B"));
 	}
 
 	@Test
@@ -97,7 +106,7 @@ public class RequestHeaderSizeGatewayFilterFactoryTest extends BaseWebClientTest
 									.filters(f -> f.setRequestHeaderSize(DataSize.of(46L, DataUnit.BYTES))).uri(uri))
 					.route("test_request_header_size_name",
 							r -> r.order(1).host("**.testrequestheadersizefiltername.org")
-									.filters(f -> f.setRequestHeaderSize(DataSize.of(1L, DataUnit.BYTES))).uri(uri))
+									.filters(f -> f.setRequestHeaderSize(DataSize.of(47L, DataUnit.BYTES))).uri(uri))
 					.build();
 		}
 

spring-cloud-gateway-server/src/test/resources/application.yml

@@ -304,7 +304,7 @@ spring:
         predicates:
           - Host=**.requestheadersize.org
         filters:
-          - RequestHeaderSize=4
+          - RequestHeaderSize=46
 
         # =====================================
       - id: rewrite_location_response_header_test