Merge "Avoid system_server crashing due to mac address is null"

        mInterfaceName = interfaceName;

        mMyAddr = myAddr;

        if (mac != null) {

            for (int i = 0; i < MAC_ADDR_LENGTH; i++) {

                mMyMac[i] = (byte) Integer.parseInt(mac.substring(

                            i*3, (i*3) + 2), 16);

            }

        }

        if (myAddr instanceof Inet6Address || peer instanceof Inet6Address) {

            throw new IllegalArgumentException("IPv6 unsupported");