Tethering: Skip link local addresses when enabling NAT

Only one entry is allowed to be added to route table 60 for all
interface ipv6 link local addresses, so skip ipv6 link local
addresses on all interfaces when enabling NAT

Change-Id: Ibbe6c2bdae83586cdd38287089715f3433bbb91f
Signed-off-by: jiaguo <jiaguo@marvell.com>

services/java/com/android/server/NetworkManagementService.java

@@ -82,6 +82,7 @@ import java.net.SocketException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.StringTokenizer;
@@ -1022,6 +1023,15 @@ public class NetworkManagementService extends INetworkManagementService.Stub
         }
     }
 
+    private List<InterfaceAddress> excludeLinkLocal(List<InterfaceAddress> addresses) {
+        ArrayList<InterfaceAddress> filtered = new ArrayList<InterfaceAddress>(addresses.size());
+        for (InterfaceAddress ia : addresses) {
+            if (!ia.getAddress().isLinkLocalAddress())
+                filtered.add(ia);
+        }
+        return filtered;
+    }
+
     private void modifyNat(String action, String internalInterface, String externalInterface)
             throws SocketException {
         final Command cmd = new Command("nat", action, internalInterface, externalInterface);
@@ -1031,8 +1041,10 @@ public class NetworkManagementService extends INetworkManagementService.Stub
         if (internalNetworkInterface == null) {
             cmd.appendArg("0");
         } else {
-            Collection<InterfaceAddress> interfaceAddresses = internalNetworkInterface
-                    .getInterfaceAddresses();
+            // Don't touch link-local routes, as link-local addresses aren't routable,
+            // kernel creates link-local routes on all interfaces automatically
+            List<InterfaceAddress> interfaceAddresses = excludeLinkLocal(
+                    internalNetworkInterface.getInterfaceAddresses());
             cmd.appendArg(interfaceAddresses.size());
             for (InterfaceAddress ia : interfaceAddresses) {
                 InetAddress addr = NetworkUtils.getNetworkPart(