parse.py

class MessageHeader(object):
    def __init__(self, priority, protocol):
        self.priority = priority
        self.protocol = protocol
        self.sender = None


def decode(bits):
    priority = bits.read('uint:2')
    broadcast = bits.read('bool')
    if broadcast:
  	     message = decodeBroadcast(priority, bits)
    else:
  	     message = decodeUnicast(priority, bits)
    message.sender = bits.read('uint:8')
    return message


broadcast_protocols = {
    
}


def decodeBroadcast(priority, bits):
    protocol = bits.read('uint:4')
    return broadcast_protocols.get(protocol, decodeUnknownBroadcast)(priority, protocol, bits)


def decodeUnknownBroadcast(priority, protocol, bits):
    subfields = bits.read('bits:14')
    return UnknownBroadcastHeader(priority, protocol, subfields)


class UnknownBroadcastHeader(MessageHeader):
    def __init__(self, priority, protocol, subfields):
        super(UnknownBroadcastHeader, self).__init__(priority, protocol)
        self.subfields = subfields


unicast_protocols = {
    0: decodeYARP,
    1: decodeRAP,
}


def decodeUnicast(priority, bits):
    protocol = bits.read('uint:4')
    ret = unicast_protocols.get(protocol, decodeUnknownUnicast)(priority, protocol, bits)
    ret.recipient = bits.read('uint:8')


def decodeUnknownUnicast(priority, protocol, bits):
    subfields = bits.read('bits:6')
    return UnknownUnicastHeader(priority, protocol, subfields)


class UnicastHeader(MessageHeader):
    def __init__(self, priority, protocol):
        super(UnicastHeader, self).__init__(priority, protocol)


class UnknownUnicastHeader(UnicastHeader):
    def __init__(self, priority, protocol, subfields):
        super(UnknownUnicastHeader, self).__init__(priority, protocol)
        self.subfields = subfields


def decodeYARP(priority, protocol, bits):
    query = bits.read('bool')
    response = bits.read('bool')
    has_hwid = bits.read('bool')
    bits.read('pad:3')
    return YARPHeader(priority, query, response, has_hwid)


class YARPHeader(UnicastHeader):
    def __init__(self, priority, query, response, has_hwid):
        super(YARPHeader, self).__init__(priority, 0)
        self.query = query
        self.response = response
        self.has_hwid = has_hwid


def decodeRAP(priority, protocol, bits):
    write = bits.read('bool')
    response = bits.read('bool')
    bits.read('pad:1')
    size = bits.read('uint:3')
    return RAPHeader(priority, write, response, size)


class RAPHeader(UnicastHeader):
    def __init__(self, priority, write, response, size):
        super(RAPHeader, self).__init__(priority, 1)
        self.write = write
        self.response = response
        self.size = size