From 2995005162004524cee0a45bc0b0bc38ca0153a1 Mon Sep 17 00:00:00 2001
From: Spencer Gibb <spencer@gibb.us>
Date: Tue, 14 Feb 2017 21:13:39 -0700
Subject: [PATCH] add RemoveNonProxyHeaders filter

---
 .../config/GatewayAutoConfiguration.java      |  6 ++
 .../RemoveNonProxyHeadersRouteFilter.java     | 64 +++++++++++++++++++
 .../cloud/gateway/support/NameUtils.java      | 18 ++++++
 3 files changed, 88 insertions(+)
 create mode 100644 src/main/java/org/springframework/cloud/gateway/filter/route/RemoveNonProxyHeadersRouteFilter.java
 create mode 100644 src/main/java/org/springframework/cloud/gateway/support/NameUtils.java

diff --git a/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java b/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java
index 1a7c7fb40..ee60eb0ec 100644
--- a/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java
+++ b/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java
@@ -22,6 +22,7 @@ import org.springframework.cloud.gateway.filter.route.AddRequestParameterRouteFi
 import org.springframework.cloud.gateway.filter.route.AddResponseHeaderRouteFilter;
 import org.springframework.cloud.gateway.filter.route.HystrixRouteFilter;
 import org.springframework.cloud.gateway.filter.route.RedirectToRouteFilter;
+import org.springframework.cloud.gateway.filter.route.RemoveNonProxyHeadersRouteFilter;
 import org.springframework.cloud.gateway.filter.route.RemoveRequestHeaderRouteFilter;
 import org.springframework.cloud.gateway.filter.route.RemoveResponseHeaderRouteFilter;
 import org.springframework.cloud.gateway.filter.route.RewritePathRouteFilter;
@@ -213,6 +214,11 @@ public class GatewayAutoConfiguration {
 		return new RedirectToRouteFilter();
 	}
 
+	@Bean(name = "RemoveNonProxyHeadersRouteFilter")
+	public RemoveNonProxyHeadersRouteFilter removeNonProxyHeadersRouteFilter() {
+		return new RemoveNonProxyHeadersRouteFilter();
+	}
+
 	@Bean(name = "RemoveRequestHeaderRouteFilter")
 	public RemoveRequestHeaderRouteFilter removeRequestHeaderRouteFilter() {
 		return new RemoveRequestHeaderRouteFilter();
diff --git a/src/main/java/org/springframework/cloud/gateway/filter/route/RemoveNonProxyHeadersRouteFilter.java b/src/main/java/org/springframework/cloud/gateway/filter/route/RemoveNonProxyHeadersRouteFilter.java
new file mode 100644
index 000000000..4ac2e3078
--- /dev/null
+++ b/src/main/java/org/springframework/cloud/gateway/filter/route/RemoveNonProxyHeadersRouteFilter.java
@@ -0,0 +1,64 @@
+package org.springframework.cloud.gateway.filter.route;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.web.server.WebFilter;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Hop-by-hop header fields, which are meaningful only for a single transport-level connection,
+ * and are not stored by caches or forwarded by proxies. The following HTTP/1.1 header fields
+ * are hop-by-hop header fields:
+ * <ul>
+ *  <li>Connection
+ *  <li>Keep-Alive
+ *  <li>Proxy-Authenticate
+ *  <li>Proxy-Authorization
+ *  <li>TE
+ *  <li>Trailer
+ *  <li>Transfer-Encoding
+ *  <li>Upgrade
+ * </ul>
+ *
+ * See https://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-14#section-7.1.3
+ *
+ * @author Spencer Gibb
+ */
+@ConfigurationProperties("spring.cloud.gateway.filter.removeNonProxyHeaders")
+public class RemoveNonProxyHeadersRouteFilter implements RouteFilter {
+
+	private static final String FAKE_HEADER = "_______force_______";
+	public static final String[] DEFAULT_HEADERS_TO_REMOVE = new String[] {"Connection", "Keep-Alive",
+			"Proxy-Authenticate", "Proxy-Authorization", "TE", "Trailer", "Transfer-Encoding", "Upgrade"};
+
+	private List<String> headers = Arrays.asList(DEFAULT_HEADERS_TO_REMOVE);
+
+	public List<String> getHeaders() {
+		return headers;
+	}
+
+	public void setHeaders(List<String> headers) {
+		this.headers = headers;
+	}
+
+	@Override
+	public WebFilter apply(String... args) {
+		//TODO: support filter args
+
+		return (exchange, chain) -> {
+			ServerHttpRequest request = exchange.getRequest().mutate()
+					.header(FAKE_HEADER, "mutable") //TODO: is there a better way?
+					.build();
+
+			request.getHeaders().remove(FAKE_HEADER);
+
+			for (String header : this.headers) {
+				request.getHeaders().remove(header);
+			}
+
+			return chain.filter(exchange.mutate().request(request).build());
+		};
+	}
+}
diff --git a/src/main/java/org/springframework/cloud/gateway/support/NameUtils.java b/src/main/java/org/springframework/cloud/gateway/support/NameUtils.java
new file mode 100644
index 000000000..6945a2b91
--- /dev/null
+++ b/src/main/java/org/springframework/cloud/gateway/support/NameUtils.java
@@ -0,0 +1,18 @@
+package org.springframework.cloud.gateway.support;
+
+import org.springframework.cloud.gateway.filter.route.RouteFilter;
+import org.springframework.cloud.gateway.handler.predicate.RoutePredicate;
+
+/**
+ * @author Spencer Gibb
+ */
+public class NameUtils {
+
+	public static String normalizePredicateName(Class<? extends RoutePredicate> clazz) {
+		return clazz.getSimpleName().replace(RoutePredicate.class.getSimpleName(), "");
+	}
+
+	public static String normalizeFilterName(Class<? extends RouteFilter> clazz) {
+		return clazz.getSimpleName().replace(RouteFilter.class.getSimpleName(), "");
+	}
+}