def deserialize(self, raw_data):
if len(raw_data) < self.HEADER_LENGTH:
return None
self.message_id, self.payload_descriptor, self.ttl, self.hops, self.payload_length = unpack(self.fmt, raw_data[:self.HEADER_LENGTH])
# Check for error heuristically in connection stream
if not (self.payload_descriptor == GnutellaBodyId.PING or
self.payload_descriptor == GnutellaBodyId.PONG or
self.payload_descriptor == GnutellaBodyId.PUSH or
self.payload_descriptor == GnutellaBodyId.QUERY or
self.payload_descriptor == GnutellaBodyId.QUERYHIT):
raise ValueError
if self.hops + self.ttl > self.MAXIMUM_SUM_TTL_HOPS:
raise ValueError
# shorten the raw_data to body
raw_data = raw_data[self.HEADER_LENGTH:]
# if check raw_data has enough data for payload
if len(raw_data) < self.payload_length:
return None
# deserialize the body
if self.payload_descriptor == GnutellaBodyId.PING:
self.body = PingBody(self)
elif self.payload_descriptor == GnutellaBodyId.PONG:
self.body = PongBody(self)
elif self.payload_descriptor == GnutellaBodyId.PUSH:
self.body = PushBody(self)
elif self.payload_descriptor == GnutellaBodyId.QUERY:
self.body = QueryBody(self)
elif self.payload_descriptor == GnutellaBodyId.QUERYHIT:
self.body = QueryHitBody(self)
else:
raise ValueError('message type is not one of PING, PONG, QUERY, QUERYHIT, PUSH')
# final check if deserialize correctly with payload_length given in the header
if self.body.deserialize(raw_data[:self.payload_length]) == None:
raise ValueError("body should be able to deserialize")
return self.payload_length + self.HEADER_LENGTH
class Message:
# count in byte
MAXIMUM_SUM_TTL_HOPS = 7
def __init__(self, message_id = None, ttl = 7):
if message_id:
self.message_id = message_id
else:
# automatically generate one
self.message_id = uuid.uuid4().bytes
self.ttl = ttl
self.hops = 0
self.body = None
self.payload_length = None
self.payload_descriptor = None
self.fmt = '!16sBBBI'
self.HEADER_LENGTH = calcsize(self.fmt)
def decrease_ttl(self, value=1):
self.ttl = self.ttl - value
self.hops = self.hops + value
def serialize(self):
assert self.body != None
assert self.payload_descriptor != None
payload = self.body.serialize()
self.payload_length = len(payload)
header = pack(self.fmt, self.message_id, self.payload_descriptor, self.ttl, self.hops, self.payload_length)
return header + payload
def deserialize(self, raw_data):
if len(raw_data) < self.HEADER_LENGTH:
return None
self.message_id, self.payload_descriptor, self.ttl, self.hops, self.payload_length = unpack(self.fmt, raw_data[:self.HEADER_LENGTH])
# Check for error heuristically in connection stream
if not (self.payload_descriptor == GnutellaBodyId.PING or
self.payload_descriptor == GnutellaBodyId.PONG or
self.payload_descriptor == GnutellaBodyId.PUSH or
self.payload_descriptor == GnutellaBodyId.QUERY or
self.payload_descriptor == GnutellaBodyId.QUERYHIT):
raise ValueError
if self.hops + self.ttl > self.MAXIMUM_SUM_TTL_HOPS:
raise ValueError
# shorten the raw_data to body
raw_data = raw_data[self.HEADER_LENGTH:]
# if check raw_data has enough data for payload
if len(raw_data) < self.payload_length:
return None
# deserialize the body
if self.payload_descriptor == GnutellaBodyId.PING:
self.body = PingBody(self)
elif self.payload_descriptor == GnutellaBodyId.PONG:
self.body = PongBody(self)
elif self.payload_descriptor == GnutellaBodyId.PUSH:
self.body = PushBody(self)
elif self.payload_descriptor == GnutellaBodyId.QUERY:
self.body = QueryBody(self)
elif self.payload_descriptor == GnutellaBodyId.QUERYHIT:
self.body = QueryHitBody(self)
else:
raise ValueError('message type is not one of PING, PONG, QUERY, QUERYHIT, PUSH')
# final check if deserialize correctly with payload_length given in the header
if self.body.deserialize(raw_data[:self.payload_length]) == None:
raise ValueError("body should be able to deserialize")
return self.payload_length + self.HEADER_LENGTH
def __repr__(self):
return "<Message: %s %s %s %s>" % (self.message_id.encode('hex_codec'), GnutellaBodyId.get_str_id(self.payload_descriptor), self.ttl, self.hops)
