'Reads header portion of packet'

def readHeader(self):

    format = '!HHHHHH'
    length = struct.calcsize(format)
    info = struct.unpack(format, self.data[self.offset:(self.offset + length)])
    self.offset += length
    self.id = info[0]
    self.flags = info[1]
    self.numQuestions = info[2]
    self.numAnswers = info[3]
    self.numAuthorities = info[4]
    self.numAdditionals = info[5]
