41 lines
1.4 KiB
Python
41 lines
1.4 KiB
Python
"""This module implements the TftpPacketFactory class, which can take a binary
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buffer, and return the appropriate TftpPacket object to represent it, via the
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parse() method."""
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from TftpShared import *
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from TftpPacketTypes import *
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class TftpPacketFactory(object):
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"""This class generates TftpPacket objects. It is responsible for parsing
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raw buffers off of the wire and returning objects representing them, via
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the parse() method."""
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def __init__(self):
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self.classes = {
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1: TftpPacketRRQ,
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2: TftpPacketWRQ,
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3: TftpPacketDAT,
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4: TftpPacketACK,
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5: TftpPacketERR,
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6: TftpPacketOACK
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}
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def parse(self, buffer):
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"""This method is used to parse an existing datagram into its
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corresponding TftpPacket object. The buffer is the raw bytes off of
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the network."""
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log.debug("parsing a %d byte packet" % len(buffer))
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(opcode,) = struct.unpack("!H", buffer[:2])
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log.debug("opcode is %d" % opcode)
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packet = self.__create(opcode)
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packet.buffer = buffer
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return packet.decode()
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def __create(self, opcode):
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"""This method returns the appropriate class object corresponding to
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the passed opcode."""
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tftpassert(self.classes.has_key(opcode),
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"Unsupported opcode: %d" % opcode)
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packet = self.classes[opcode]()
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return packet
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