Add new route.hasGateway() api

Fixes issues brought in by change to isHostRoute.  isHostRoute
was technically correct, but the callers really wanted hasNextHop
behavior.

bug:8597268
Change-Id: I360761ccfa98b2ba34642f717a78fa71ec1bae4f

core/java/android/net/RouteInfo.java

@@ -60,6 +60,7 @@ public class RouteInfo implements Parcelable {
 
     private final boolean mIsDefault;
     private final boolean mIsHost;
+    private final boolean mHasGateway;
 
     /**
      * Constructs a RouteInfo object.
@@ -97,6 +98,8 @@ public class RouteInfo implements Parcelable {
                 gateway = Inet6Address.ANY;
             }
         }
+        mHasGateway = (!gateway.isAnyLocalAddress());
+
         mDestination = new LinkAddress(NetworkUtils.getNetworkPart(destination.getAddress(),
                 destination.getNetworkPrefixLength()), destination.getNetworkPrefixLength());
         mGateway = gateway;
@@ -171,6 +174,10 @@ public class RouteInfo implements Parcelable {
         return mIsHost;
     }
 
+    public boolean hasGateway() {
+        return mHasGateway;
+    }
+
     public String toString() {
         String val = "";
         if (mDestination != null) val = mDestination.toString();

services/java/com/android/server/ConnectivityService.java

@@ -1470,8 +1470,7 @@ public class ConnectivityService extends IConnectivityManager.Stub {
             loge("Error modifying route - no interface name");
             return false;
         }
-
-        if (r.isHostRoute() == false) {
+        if (r.hasGateway()) {
             RouteInfo bestRoute = RouteInfo.selectBestRoute(lp.getAllRoutes(), r.getGateway());
             if (bestRoute != null) {
                 if (bestRoute.getGateway().equals(r.getGateway())) {