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"""of_core utility functions and classes.""" |
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import struct |
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from collections import OrderedDict |
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from pyof.foundation.exceptions import PackException, UnpackException |
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from pyof.v0x01.common.header import Type as OFPTYPE |
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from kytos.core import KytosEvent |
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def of_slicer(remaining_data): |
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"""Slice a raw `bytes` instance into OpenFlow packets.""" |
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data_len = len(remaining_data) |
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pkts = [] |
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while data_len > 3: |
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length_field = struct.unpack('!H', remaining_data[2:4])[0] |
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if data_len >= length_field: |
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pkts.append(remaining_data[:length_field]) |
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remaining_data = remaining_data[length_field:] |
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data_len = len(remaining_data) |
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else: |
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break |
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return pkts, remaining_data |
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def _unpack_int(packet, offset=0, size=None): |
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if size is None: |
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if isinstance(packet, int): |
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return packet |
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size = len(packet) |
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return int.from_bytes(packet[offset:offset + size], byteorder='big') |
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def _emit_message(controller, connection, message, direction): |
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"""Emit a KytosEvent for every incoming or outgoing message.""" |
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if direction == 'in': |
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address_type = 'source' |
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message_buffer = controller.buffers.msg_in |
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elif direction == 'out': |
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address_type = 'destination' |
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message_buffer = controller.buffers.msg_out |
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else: |
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raise Exception("direction must be 'in' or 'out'") |
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name = message.header.message_type.name.lower() |
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hex_version = 'v0x%0.2x' % (message.header.version + 0) |
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of_event = KytosEvent( |
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name=f"kytos/of_core.{hex_version}.messages.{direction}.{name}", |
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content={'message': message, |
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address_type: connection}) |
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message_buffer.put(of_event) |
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def emit_message_in(controller, connection, message): |
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"""Emit a KytosEvent for every incoming message.""" |
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_emit_message(controller, connection, message, 'in') |
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def emit_message_out(controller, connection, message): |
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"""Emit a KytosEvent for every outgoing message.""" |
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_emit_message(controller, connection, message, 'out') |
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class GenericHello: |
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"""Version agnostic OpenFlow Hello Message.""" |
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header_sizes = OrderedDict( |
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version=1, |
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type=1, |
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length=2, |
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xid=4) |
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elem_type_size = 2 |
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elem_len_size = 2 |
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OFPHET_VERSIONBITMAP = 1 |
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class GenericHeader: |
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xid = None |
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type = None |
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length = None |
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def __init__(self, *, packet=None, versions=None, xid=None): |
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"""Initialize from a binary packet or from initial versions and xid. |
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Parameters: |
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packet: binary packet (bytes) to be unpacked and used to |
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initialize the message |
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versions: list of versions used to build the version bitmap |
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xid: xid to be used in the message |
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""" |
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self.header = self.GenericHeader() |
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self.header.message_type = OFPTYPE.OFPT_HELLO |
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if not any((packet, versions)): |
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raise Exception('either packet or versions must be set.') |
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if packet is not None: |
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self.unpack(packet) |
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else: |
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if xid is None: |
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self.header.xid = 0 |
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if versions is not None: |
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self.versions = versions |
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self.header.version = max(versions) |
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if xid is not None: |
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self.header.xid = xid |
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def pack(self): |
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"""Encode OpenFlow packet.""" |
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versions = self.versions |
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xid = self.header.xid |
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packet_version = max(versions) |
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if packet_version > 31: |
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raise PackException |
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versions_value = 0 |
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for version in versions: |
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versions_value += (1 << version) |
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bitmap = versions_value.to_bytes(4, byteorder='big') |
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version_byte = packet_version.to_bytes(self.header_sizes['version'], |
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byteorder='big') |
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xid_byte = xid.to_bytes(self.header_sizes['xid'], |
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byteorder='big') |
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packet = version_byte + b'\x00\x00\x10' + xid_byte + \ |
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b'\x00\x01\x00\x08' + bitmap |
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return packet |
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def unpack(self, packet): |
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"""Decode OpenFlow packet.""" |
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offset = 0 |
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# self.header = self.generic_Header() |
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for key, size in self.header_sizes.items(): |
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setattr(self.header, key, _unpack_int(packet, offset, size)) |
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offset += size |
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if self.header.type != 0: |
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raise UnpackException |
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elements = {} |
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try: |
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while offset < self.header.length: |
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elem_type = _unpack_int( |
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packet, offset, self.elem_type_size) |
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offset += self.elem_type_size |
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elem_length = _unpack_int( |
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packet, offset, self.elem_len_size) |
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offset += self.elem_len_size |
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elem_header_size = self.elem_type_size - self.elem_len_size |
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elem_value_size = elem_length - elem_header_size |
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elem_value = _unpack_int( |
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packet, offset, elem_value_size) |
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elements[elem_type] = elem_value |
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except IndexError: |
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raise UnpackException |
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self.elements = elements |
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if self.OFPHET_VERSIONBITMAP in self.elements: |
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bitmap = self.elements[self.OFPHET_VERSIONBITMAP] |
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versions = [] |
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for i in range(32): |
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if ((1 << i) & bitmap) != 0: |
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versions.append(i) |
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self.versions = versions |
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self.version_bitmap = bitmap |
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else: |
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self.versions = None |
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class NegotiationException(Exception): |
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"""Exception raised when OpenFlow version negotiation failed.""" |
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def __str__(self): |
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return "OF version negotiation failed: " + super().__str__() |
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kytos /
of_core
