fix memory init issue

and another place where dns data needs to be copied

osdep/MacEthernetTap.hpp

@@ -56,6 +56,7 @@ public:
 	virtual void setFriendlyName(const char *friendlyName);
 	virtual void scanMulticastGroups(std::vector<MulticastGroup> &added,std::vector<MulticastGroup> &removed);
 	virtual void setMtu(unsigned int mtu);
+	virtual void setDns(const char *domain, const std::vector<InetAddress> &servers);
 
 	void threadMain()
 		throw();