Use dns proxy a bit.

Sets the current default interface and sets the dns per interface.
port of changes 23041 and 22098 from opensource.
bug:5060618

Change-Id: I80e7ef88727eeb8ff2b48059f69b270e5a6b5c16

core/java/android/net/NetworkUtils.java

@@ -20,6 +20,7 @@ import java.net.InetAddress;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
 import java.net.UnknownHostException;
+import java.util.Collection;
 
 import android.util.Log;
 
@@ -235,4 +236,18 @@ public class NetworkUtils {
             throw new IllegalArgumentException(e);
         }
     }
+
+    /**
+     * Create a string array of host addresses from a collection of InetAddresses
+     * @param addrs a Collection of InetAddresses
+     * @return an array of Strings containing their host addresses
+     */
+    public static String[] makeStrings(Collection<InetAddress> addrs) {
+        String[] result = new String[addrs.size()];
+        int i=0;
+        for (InetAddress addr : addrs) {
+            result[i++] = addr.getHostAddress();
+        }
+        return result;
+    }
 }

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

@@ -1757,8 +1757,19 @@ public class ConnectivityService extends IConnectivityManager.Stub {
             LinkProperties p = nt.getLinkProperties();
             if (p == null) return;
             Collection<InetAddress> dnses = p.getDnses();
+            try {
+                mNetd.setDnsServersForInterface(p.getInterfaceName(),
+                        NetworkUtils.makeStrings(dnses));
+            } catch (Exception e) {
+                Slog.e(TAG, "exception setting dns servers: " + e);
+            }
             boolean changed = false;
             if (mNetConfigs[netType].isDefault()) {
+                try {
+                    mNetd.setDefaultInterfaceForDns(p.getInterfaceName());
+                } catch (Exception e) {
+                    Slog.e(TAG, "exception setting default dns interface: " + e);
+                }
                 int j = 1;
                 if (dnses.size() == 0 && mDefaultDns != null) {
                     String dnsString = mDefaultDns.getHostAddress();