Use a packet structure to wrap raw data
Signed-off-by: Yohann D'ANELLO <ynerant@crans.org>
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@ -48,10 +48,79 @@ class Squinnondation:
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while True:
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data, addr = squirrel.receive_raw_data()
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print("received message: %s" % data)
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pkt = Packet.unmarshal(data)
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print("received message: %d %d %d %s" % (pkt.magic, pkt.version, pkt.body_length, pkt.body.raw_data))
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print(str(pkt.marshal()))
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# squirrel.send_raw_data(hazelnut, b"Hello squirrel!")
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class TLV:
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"""
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The Tag-Length-Value contains the different type of data that can be sent.
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TODO: add subclasses for each type of TLV
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"""
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type: int
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raw_data: bytes
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def validate_data(self) -> bool:
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"""
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Ensure that the TLV is well-formed.
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Raises a ValueError if it is not the case.
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TODO: Make some tests
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"""
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return True
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class Packet:
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"""
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A Packet is a wrapper around the
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"""
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magic: int
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version: int
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body_length: int
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body: TLV
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def validate_data(self) -> bool:
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"""
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Ensure that the packet is well-formed.
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Raises a ValueError if the packet contains bad data.
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"""
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if self.magic != 95:
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raise ValueError("The magic code of the packet must be 95, found: {:d}".format(self.magic))
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if self.version != 0:
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raise ValueError("The version of the packet is not supported: {:d}".format(self.version))
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if not (0 <= self.body_length <= 120):
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raise ValueError("The body length of the packet is negative or too high. It must be between 0 and 1020,"
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"found: {:d}".format(self.body_length))
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return self.body.validate_data()
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@staticmethod
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def unmarshal(data: bytes) -> "Packet":
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"""
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Read raw data and build the packet wrapper.
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Raises a ValueError whenever the data is invalid.
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"""
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pkt = Packet()
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pkt.magic = data[0]
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pkt.version = data[1]
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pkt.body_length = int.from_bytes(data[2:4], byteorder="big")
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pkt.body = TLV()
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pkt.body.raw_data = data[4:4+pkt.body_length]
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pkt.validate_data()
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return pkt
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def marshal(self) -> bytes:
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"""
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Compute the byte array data associated to the packet.
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"""
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data = bytes([self.magic, self.version])
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data += self.body_length.to_bytes(2, "big")
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data += self.body.raw_data
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return data
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class Hazelnut:
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"""
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A hazelnut is a connected client, with its socket.
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