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"""General Unpack utils for python-openflow.
This package was moved from kytos/of_core for the purpose of creating a generic
method to perform package unpack independent of the OpenFlow version.
"""
from pyof import v0x01, v0x04
from pyof.foundation.exceptions import UnpackException
from pyof.v0x01.common import utils as u_v0x01 # pylint: disable=unused-import
from pyof.v0x04.common import utils as u_v0x04 # pylint: disable=unused-import
PYOF_VERSION_LIBS = {0x01: v0x01,
0x04: v0x04}
def validate_packet(packet):
"""Check if packet is valid OF packet.
Raises:
UnpackException: If the packet is invalid.
"""
if not isinstance(packet, bytes):
raise UnpackException('invalid packet')
packet_length = len(packet)
if packet_length < 8 or packet_length > 2**16:
raise UnpackException('invalid packet')
if packet_length != int.from_bytes(packet[2:4], byteorder='big'):
raise UnpackException('invalid packet')
version = packet[0]
if version == 0 or version >= 128:
raise UnpackException('invalid packet')
def unpack(packet):
"""Unpack the OpenFlow Packet and returns a message.
Args:
packet: buffer with the openflow packet.
Returns:
GenericMessage: Message unpacked based on openflow packet.
Raises:
UnpackException: if the packet can't be unpacked.
"""
validate_packet(packet)
version = packet[0]
try:
pyof_lib = PYOF_VERSION_LIBS[version]
except KeyError:
raise UnpackException('Version not supported')
try:
message = pyof_lib.common.utils.unpack_message(packet)
return message
except (UnpackException, ValueError) as exception:
raise UnpackException(exception)
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