Improved zuul proxy header support.

- add zuul.add-host-header property to add Host header
- add port to X-Forwarded-Host as defined in RFC 7239
- extract PreDecorationFilter.filterOrder() into a public constant

fixes gh-1108

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

@@ -82,6 +82,11 @@ public class ZuulProperties {
 	 */
 	private boolean addProxyHeaders = true;
 
+	/**
+	 * Flag to determine whether the proxy forwards the Host header.
+	 */
+	private boolean addHostHeader = false;
+
 	/**
 	 * Set of service names not to consider for proxying automatically. By default all
 	 * services in the discovery client will be proxied.

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

@@ -19,6 +19,8 @@
 import java.net.MalformedURLException;
 import java.net.URL;
 
+import javax.servlet.http.HttpServletRequest;
+
 import org.springframework.cloud.netflix.zuul.filters.ProxyRequestHelper;
 import org.springframework.cloud.netflix.zuul.filters.Route;
 import org.springframework.cloud.netflix.zuul.filters.RouteLocator;
@@ -36,6 +38,8 @@
 @CommonsLog
 public class PreDecorationFilter extends ZuulFilter {
 
+	public static final int FILTER_ORDER = 5;
+
 	private RouteLocator routeLocator;
 
 	private String dispatcherServletPath;
@@ -58,7 +62,7 @@ public PreDecorationFilter(RouteLocator routeLocator, String dispatcherServletPa
 
 	@Override
 	public int filterOrder() {
-		return 5;
+		return FILTER_ORDER;
 	}
 
 	@Override
@@ -115,8 +119,7 @@ else if (location.startsWith("forward:")) {
 					ctx.addOriginResponseHeader("X-Zuul-ServiceId", location);
 				}
 				if (this.properties.isAddProxyHeaders()) {
-					ctx.addZuulRequestHeader("X-Forwarded-Host",
-							ctx.getRequest().getServerName());
+					ctx.addZuulRequestHeader("X-Forwarded-Host", toHostHeader(ctx.getRequest()));
 					ctx.addZuulRequestHeader("X-Forwarded-Port",
 							String.valueOf(ctx.getRequest().getServerPort()));
 					ctx.addZuulRequestHeader(ZuulHeaders.X_FORWARDED_PROTO,
@@ -149,6 +152,9 @@ else if (!xforwardedfor.contains(remoteAddr)) { // Prevent duplicates
 					}
 					ctx.addZuulRequestHeader("X-Forwarded-For", xforwardedfor);
 				}
+				if (this.properties.isAddHostHeader()) {
+					ctx.addZuulRequestHeader("Host", toHostHeader(ctx.getRequest()));
+				}
 			}
 		}
 		else {
@@ -182,6 +188,15 @@ else if (!xforwardedfor.contains(remoteAddr)) { // Prevent duplicates
 		return null;
 	}
 
+	private String toHostHeader(HttpServletRequest request) {
+		int port = request.getServerPort();
+		if ((port == 80 && "http".equals(request.getScheme())) || (port == 443 && "https".equals(request.getScheme()))) {
+			return request.getServerName();
+		} else {
+			return request.getServerName() + ":" + port;
+		}
+	}
+
 	private URL getUrl(String target) {
 		try {
 			return new URL(target);

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

@@ -90,6 +90,34 @@ public void skippedIfForwardToSet() throws Exception {
 		assertEquals(false, this.filter.shouldFilter());
 	}
 
+	@Test
+	public void xForwardedHostHasPort() throws Exception {
+		this.properties.setPrefix("/api");
+		this.request.setRequestURI("/api/foo/1");
+		this.request.setRemoteAddr("5.6.7.8");
+		this.request.setServerPort(8080);
+		this.routeLocator.addRoute(
+				new ZuulRoute("foo", "/foo/**", "foo", null, false, null, null));
+		this.filter.run();
+		RequestContext ctx = RequestContext.getCurrentContext();
+		assertEquals("localhost:8080", ctx.getZuulRequestHeaders().get("x-forwarded-host"));
+	}
+
+	@Test
+	public void hostHeaderSet() throws Exception {
+		this.properties.setPrefix("/api");
+		this.properties.setAddHostHeader(true);
+		this.request.setRequestURI("/api/foo/1");
+		this.request.setRemoteAddr("5.6.7.8");
+		this.request.setServerPort(8080);
+		this.routeLocator.addRoute(
+				new ZuulRoute("foo", "/foo/**", "foo", null, false, null, null));
+		this.filter.run();
+		RequestContext ctx = RequestContext.getCurrentContext();
+		assertEquals("localhost:8080", ctx.getZuulRequestHeaders().get("x-forwarded-host"));
+		assertEquals("localhost:8080", ctx.getZuulRequestHeaders().get("host"));
+	}
+
 	@Test
 	public void prefixRouteAddsHeader() throws Exception {
 		this.properties.setPrefix("/api");