Add whitelist hosts and sensitive headers

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

@@ -1227,6 +1227,15 @@ span all services and supersede any other route specification.
 This means that all calls such as "/myusers/101" will be forwarded to "/101" on the "users" service.
 But calls including "/admin/" will not resolve.
 
+=== Sensitive Headers
+
+It's OK to share headers between services in the same system, but you
+probably don't want sensitive headers leaking downstream into external
+servers. Thus if you use an explicit URL in a route configuration (as
+opposed to a service id), then you can also specify a list of
+sensitive headers and a whitelist of host patterns to not receive
+those headers.
+
 === Strangulation Patterns and Local Forwards
 
 A common pattern when migrating an existing application or API is to

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/ProxyRequestHelper.java

@@ -19,8 +19,10 @@ package org.springframework.cloud.netflix.zuul.filters;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.net.URL;
 import java.nio.charset.Charset;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -37,6 +39,7 @@ import org.springframework.boot.actuate.trace.TraceRepository;
 import org.springframework.http.HttpHeaders;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
+import org.springframework.util.PatternMatchUtils;
 import org.springframework.web.util.UriTemplate;
 import org.springframework.web.util.UriUtils;
 import org.springframework.web.util.WebUtils;
@@ -65,8 +68,20 @@ public class ProxyRequestHelper {
 
 	private Set<String> ignoredHeaders = new LinkedHashSet<>();
 
+	private Set<String> sensitiveHeaders = new LinkedHashSet<>();
+
+	private Set<String> whitelistHosts = new LinkedHashSet<>();
+
+	public void setWhitelistHosts(Set<String> whitelistHosts) {
+		this.whitelistHosts.addAll(whitelistHosts);
+	}
+
+	public void setSensitiveHeaders(Set<String> sensitiveHeaders) {
+		this.sensitiveHeaders.addAll(sensitiveHeaders);
+	}
+
 	public void setIgnoredHeaders(Set<String> ignoredHeaders) {
-		this.ignoredHeaders = ignoredHeaders;
+		this.ignoredHeaders.addAll(ignoredHeaders);
 	}
 
 	public void setTraces(TraceRepository traces) {
@@ -182,11 +197,28 @@ public class ProxyRequestHelper {
 		for (String name : this.ignoredHeaders) {
 			set.add(name.toLowerCase());
 		}
+		for (String name : getSensitiveHeaders(ctx)) {
+			set.add(name.toLowerCase());
+		}
 		for (String name : names) {
 			set.add(name.toLowerCase());
 		}
 	}
 
+	private Collection<String> getSensitiveHeaders(RequestContext ctx) {
+		URL uri = ctx.getRouteHost();
+		if (uri == null) {
+			return Collections.emptySet();
+		}
+		String host;
+		host = uri.getHost();
+		if (PatternMatchUtils.simpleMatch(this.whitelistHosts.toArray(new String[0]),
+				host)) {
+			return this.sensitiveHeaders;
+		}
+		return Collections.emptySet();
+	}
+
 	public boolean isIncludedHeader(String headerName) {
 		String name = headerName.toLowerCase();
 		RequestContext ctx = RequestContext.getCurrentContext();

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/ZuulProperties.java

@@ -66,6 +66,8 @@ public class ZuulProperties {
 
 	private Set<String> ignoredHeaders = new LinkedHashSet<>();
 
+	private Sensitive sensitive = new Sensitive();
+
 	private String servletPath = "/zuul";
 
 	private boolean ignoreLocalService = true;
@@ -103,6 +105,21 @@ public class ZuulProperties {
 		}
 	}
 
+	@Data
+	@AllArgsConstructor
+	@NoArgsConstructor
+	public static class Sensitive {
+		/**
+		 * Headers that are considered sensitive, and not passed on through a proxy.
+		 */
+		private Set<String> headers = new LinkedHashSet<>(Arrays.asList("Cookie"));
+		/**
+		 * Hostname (patterns) that are considered safe and can receive sensitive headers
+		 * when a route is specified as a URL.
+		 */
+		private Set<String> whitelist = new LinkedHashSet<>(Arrays.asList("localhost"));
+	}
+
 	@Data
 	@AllArgsConstructor
 	@NoArgsConstructor

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/SimpleHostRoutingFilter.java

@@ -209,9 +209,10 @@ public class SimpleHostRoutingFilter extends ZuulFilter {
 					.build();
 
 			this.connectionManager = new PoolingHttpClientConnectionManager(registry);
-			this.connectionManager.setMaxTotal(hostProperties.getMaxTotalConnections());
 			this.connectionManager
-					.setDefaultMaxPerRoute(hostProperties.getMaxPerRouteConnections());
+					.setMaxTotal(this.hostProperties.getMaxTotalConnections());
+			this.connectionManager.setDefaultMaxPerRoute(
+					this.hostProperties.getMaxPerRouteConnections());
 			return this.connectionManager;
 		}
 		catch (Exception ex) {

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/filters/ProxyRequestHelperTests.java

@@ -17,10 +17,9 @@
 package org.springframework.cloud.netflix.zuul.filters;
 
 import java.io.IOException;
-import java.util.Collection;
+import java.net.URL;
+import java.util.Collections;
 import java.util.List;
-import java.util.Map;
-import java.util.Set;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -28,7 +27,6 @@ import org.mockito.Mock;
 import org.springframework.boot.actuate.trace.InMemoryTraceRepository;
 import org.springframework.boot.actuate.trace.Trace;
 import org.springframework.boot.actuate.trace.TraceRepository;
-import org.springframework.boot.autoconfigure.web.ResourceProperties;
 import org.springframework.http.HttpHeaders;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
@@ -163,7 +161,7 @@ public class ProxyRequestHelperTests {
 	}
 
 	@Test
-	public void getQueryString(){
+	public void getQueryString() {
 		MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
 		params.add("a", "1234");
 		params.add("b", "5678");
@@ -174,7 +172,7 @@ public class ProxyRequestHelperTests {
 	}
 
 	@Test
-	public void getQueryStringWithEmptyParam(){
+	public void getQueryStringWithEmptyParam() {
 		MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
 		params.add("wsdl", "");
 
@@ -182,4 +180,36 @@ public class ProxyRequestHelperTests {
 
 		assertThat(queryString, is("?wsdl"));
 	}
+
+	@Test
+	public void ignoreSensitiveHeadersMatchingHost() throws Exception {
+		ProxyRequestHelper helper = new ProxyRequestHelper();
+		helper.setSensitiveHeaders(Collections.singleton("Cookie"));
+		helper.setWhitelistHosts(Collections.singleton("*"));
+		RequestContext context = RequestContext.getCurrentContext();
+		context.setRouteHost(new URL("http://example.com"));
+		helper.addIgnoredHeaders();
+		assertThat(helper.isIncludedHeader("Cookie"), is(false));
+	}
+
+	@Test
+	public void ignoreSensitiveHeadersNotMatching() throws Exception {
+		ProxyRequestHelper helper = new ProxyRequestHelper();
+		helper.setSensitiveHeaders(Collections.singleton("Cookie"));
+		helper.setWhitelistHosts(Collections.singleton("foo.com"));
+		RequestContext context = RequestContext.getCurrentContext();
+		context.setRouteHost(new URL("http://example.com"));
+		helper.addIgnoredHeaders();
+		assertThat(helper.isIncludedHeader("Cookie"), is(true));
+	}
+
+	@Test
+	public void ignoreSensitiveHeadersWhenNoRoute() throws Exception {
+		ProxyRequestHelper helper = new ProxyRequestHelper();
+		helper.setSensitiveHeaders(Collections.singleton("Cookie"));
+		helper.setWhitelistHosts(Collections.singleton("foo.com"));
+		RequestContext context = RequestContext.getCurrentContext();
+		helper.addIgnoredHeaders();
+		assertThat(helper.isIncludedHeader("Cookie"), is(true));
+	}
 }