Prevent potential stall on dns proxy operations.

Update wire protocol to return and process error code first. This
will make sure dns proxy operations do not stall when an internal
error happens.

Change-Id: I65595abb0638722ccd877f69057bd435ca06e524
diff --git a/ResponseCode.h b/ResponseCode.h
index b01c141..04a6644 100644
--- a/ResponseCode.h
+++ b/ResponseCode.h
@@ -44,10 +44,12 @@
     static const int InterfaceTxThrottleResult = 219;
     static const int QuotaCounterResult        = 220;
     static const int TetheringStatsResult      = 221;
+    static const int DnsProxyQueryResult       = 222;
 
     // 400 series - The command was accepted but the requested action
     // did not take place.
-    static const int OperationFailed = 400;
+    static const int OperationFailed           = 400;
+    static const int DnsProxyOperationFailed   = 401;
 
     // 500 series - The command was not accepted and the requested
     // action did not take place.