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"""General Unpack utils for python-openflow. |
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This package was moved from kytos/of_core for the purpose of creating a generic |
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method to perform package unpack independent of the OpenFlow version. |
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""" |
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from pyof import v0x01, v0x04 |
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from pyof.foundation.exceptions import UnpackException |
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PYOF_VERSION_LIBS = {0x01: v0x01, |
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0x04: v0x04} |
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def validate_packet(packet): |
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"""Check if packet is valid OF packet. |
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Raises: |
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UnpackException: If the packet is invalid. |
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""" |
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if not isinstance(packet, bytes): |
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raise UnpackException('invalid packet') |
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packet_length = len(packet) |
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if packet_length < 8 or packet_length > 2**16: |
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raise UnpackException('invalid packet') |
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if packet_length != int.from_bytes(packet[2:4], |
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byteorder='big'): |
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raise UnpackException('invalid packet') |
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version = packet[0] |
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if version == 0 or version >= 128: |
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raise UnpackException('invalid packet') |
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def unpack(packet): |
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"""Unpack the OpenFlow Packet and returns a message. |
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Returns: |
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GenericMessage: Message unpacked based on openflow packet. |
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Raises: |
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UnpackException: if the packet can't be unpacked. |
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""" |
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validate_packet(packet) |
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version = packet[0] |
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try: |
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pyof_lib = PYOF_VERSION_LIBS[version] |
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except KeyError: |
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raise UnpackException('Version not supported') |
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try: |
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header = pyof_lib.common.header.Header() |
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header.unpack(packet[:header.get_size()]) |
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message = pyof_lib.common.utils.new_message_from_header(header) |
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binary_data = packet[header.get_size():] |
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binary_data_size = header.length - header.get_size() |
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if binary_data and len(binary_data) == binary_data_size: |
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message.unpack(binary_data) |
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return message |
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except (UnpackException, ValueError) as exception: |
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raise UnpackException(exception) |
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kytos /
python-openflow
