Adds max response header configuration.

fixes gh-1457

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

@@ -572,7 +572,14 @@ else if (pool.getType() == FIXED) {
 			}
 
 			HttpClient httpClient = HttpClient.create(connectionProvider)
-					.tcpConfiguration(tcpClient -> {
+					.httpResponseDecoder(spec -> {
+						if (properties.getMaxHeaderSize() != null) {
+							// cast to int is ok, since @Max is Integer.MAX_VALUE
+							spec.maxHeaderSize(
+									(int) properties.getMaxHeaderSize().toBytes());
+						}
+						return spec;
+					}).tcpConfiguration(tcpClient -> {
 
 						if (properties.getConnectTimeout() != null) {
 							tcpClient = tcpClient.option(

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

@@ -27,6 +27,8 @@
 import java.util.Collection;
 import java.util.List;
 
+import javax.validation.constraints.Max;
+
 import reactor.netty.resources.ConnectionProvider;
 import reactor.netty.tcp.SslProvider;
 
@@ -35,6 +37,7 @@
 import org.springframework.boot.web.server.WebServerException;
 import org.springframework.core.style.ToStringCreator;
 import org.springframework.util.ResourceUtils;
+import org.springframework.util.unit.DataSize;
 
 /**
  * Configuration properties for the Netty {@link reactor.netty.http.client.HttpClient}.
@@ -48,6 +51,9 @@ public class HttpClientProperties {
 	/** The response timeout. */
 	private Duration responseTimeout;
 
+	/** The max response header size. */
+	private DataSize maxHeaderSize;
+
 	/** Pool configuration for Netty HttpClient. */
 	private Pool pool = new Pool();
 
@@ -76,6 +82,15 @@ public void setResponseTimeout(Duration responseTimeout) {
 		this.responseTimeout = responseTimeout;
 	}
 
+	@Max(Integer.MAX_VALUE)
+	public DataSize getMaxHeaderSize() {
+		return maxHeaderSize;
+	}
+
+	public void setMaxHeaderSize(DataSize maxHeaderSize) {
+		this.maxHeaderSize = maxHeaderSize;
+	}
+
 	public Pool getPool() {
 		return pool;
 	}
@@ -114,6 +129,7 @@ public String toString() {
 		return new ToStringCreator(this)
 				.append("connectTimeout", connectTimeout)
 				.append("responseTimeout", responseTimeout)
+				.append("maxHeaderSize", maxHeaderSize)
 				.append("pool", pool)
 				.append("proxy", proxy)
 				.append("ssl", ssl)