def DecodeFromData(self, stream):
'''
Decodes a packet from a data stream.
@type stream: Stream (file-like) object
@param stream: Stream from which to decode the packet.
@raise IncompletePacket: Raised if not enough data is present.
@raise CorruptPacket: Raised if the data is invalid.
'''
# Read in the header.
try:
ph_type = BinaryStructs.DeserializeUint16(stream)
ph_flags = BinaryStructs.DeserializeUint16(stream)
except BinaryStructs.EndOfFile:
# Packet seems incomplete
raise IncompletePacket
# Validate the packet header.
if ph_type > MAX_VALID_PACKET:
# Unknown type; corrupt packet.
raise CorruptPacket("Invalid packet type in header.")
# Now try reading the body.
compressed = bool(ph_flags & HeaderFlag_zlib)
self._GetBodyFromBinary(stream, compressed)
def DeserializeBody(self, stream):
# check the protocol signature
signature = stream.read(len(ProtocolSignature))
if len(signature) != len(ProtocolSignature):
raise IncompletePacket
self.Signature = signature
# check the version
try:
self.Revision = BinaryStructs.DeserializeUint16(stream)
self.MajorVersion = BinaryStructs.DeserializeUint16(stream)
self.MinorVersion = BinaryStructs.DeserializeUint16(stream)
except BinaryStructs.EndOfFile:
raise IncompletePacket
except:
msg = "Unhandled exception while deserializing packet type 0.\n\n"
msg += traceback.format_exc()
logging.error(msg)
raise CorruptPacket
def DeserializeBody(self, stream):
# Read values.
try:
self.RequestSerial = BinaryStructs.DeserializeUint32(stream)
self.ReasonCode = BinaryStructs.DeserializeUint16(stream)
except BinaryStructs.EndOfFile:
raise IncompletePacket
except:
msg = "Unhandled exception in DeserializeBody, packet type 4.\n\n"
msg += traceback.format_exc()
logging.error(msg)
raise CorruptPacket
def BuildPacketFromStream(stream, connection):
'''
Attempts to build a packet from a data stream.
@type stream: file-like object
@param stream: Data stream to build packet from.
@type connection: Networking.BaseConnectionHandler
@param connection: Connection with which to associate the packet.
@raise IncompletePacket: Raised if not enough data is present.
@raise CorruptPacket: Raised if something is wrong with the data.
@return: A Packet object, or an object of a Packet subclass.
'''
# try peeking ahead at the packet type
startpos = stream.tell()
try:
type = BinaryStructs.DeserializeUint16(stream)
stream.seek(startpos)
except:
# not enough data, make sure we rewind
stream.seek(startpos)
raise IncompletePacket
# check the type
if type < 0 or type > MAX_VALID_PACKET:
# packet type is out of bounds
raise CorruptPacket
# now build up a packet of the appropriate type
try:
PacketProto = PacketTypes[type]
except KeyError:
# unrecognized packet type
raise CorruptPacket
NewPacket = PacketProto(connection)
# and now fill in the packet with the data...
NewPacket.DecodeFromData(stream)
return NewPacket
def DeserializeBody(self, stream):
# Read data.
try:
self.Reason = BinaryStructs.DeserializeUint16(stream)
except BinaryStructs.EndOfFile:
raise IncompletePacket