def read_string(self, len):
        """Reads a string of a given length from the packet"""
        format = '!' + str(len) + 's'
        length = struct.calcsize(format)
        info = struct.unpack(format,
                self.data[self.offset:self.offset + length])
        self.offset += length
        return info[0]
Reads a string of a given length from the packet