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"""Module with all classes related to links. |
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Links are low level abstractions representing connections between two |
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interfaces. |
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""" |
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import hashlib |
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import json |
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import random |
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from kytos.core.common import GenericEntity |
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from kytos.core.exceptions import (KytosLinkCreationError, |
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KytosNoTagAvailableError) |
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from kytos.core.interface import TAGType |
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class Link(GenericEntity): |
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"""Define a link between two Endpoints.""" |
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def __init__(self, endpoint_a, endpoint_b): |
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"""Create a Link instance and set its attributes. |
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Two kytos.core.interface.Interface are required as parameters. |
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""" |
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if endpoint_a is None: |
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raise KytosLinkCreationError("endpoint_a cannot be None") |
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if endpoint_b is None: |
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raise KytosLinkCreationError("endpoint_b cannot be None") |
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self.endpoint_a = endpoint_a |
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self.endpoint_b = endpoint_b |
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super().__init__() |
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def __hash__(self): |
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return hash(self.id) |
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def is_enabled(self): |
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"""Override the is_enabled method. |
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We consider a link enabled when all the interfaces are enabled. |
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Returns: |
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boolean: True if both interfaces are enabled, False otherwise. |
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""" |
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return (self._enabled and self.endpoint_a.is_enabled() and |
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self.endpoint_b.is_enabled()) |
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def is_active(self): |
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"""Override the is_active method. |
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We consider a link active whether all the interfaces are active. |
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Returns: |
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boolean: True if the interfaces are active, othewrise False. |
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""" |
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return (self._active and self.endpoint_a.is_active() and |
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self.endpoint_b.is_active()) |
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def __eq__(self, other): |
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"""Check if two instances of Link are equal.""" |
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return self.id == other.id |
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@property |
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def id(self): # pylint: disable=invalid-name |
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"""Return id from Link intance. |
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Returns: |
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string: link id. |
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""" |
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dpid_a = self.endpoint_a.switch.dpid |
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port_a = self.endpoint_a.port_number |
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dpid_b = self.endpoint_b.switch.dpid |
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port_b = self.endpoint_b.port_number |
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if dpid_a < dpid_b: |
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elements = (dpid_a, port_a, dpid_b, port_b) |
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elif dpid_a > dpid_b: |
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elements = (dpid_b, port_b, dpid_a, port_a) |
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elif port_a < port_b: |
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elements = (dpid_a, port_a, dpid_b, port_b) |
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else: |
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elements = (dpid_b, port_b, dpid_a, port_a) |
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str_id = "%s:%s:%s:%s" % elements |
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return hashlib.sha256(str_id.encode('utf-8')).hexdigest() |
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@property |
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def available_tags(self): |
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"""Return the available tags for the link. |
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Based on the endpoint tags. |
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""" |
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return [tag for tag in self.endpoint_a.available_tags if tag in |
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self.endpoint_b.available_tags] |
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def use_tag(self, tag): |
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"""Remove a specific tag from available_tags if it is there. |
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Deprecated: use only the get_next_available_tag method. |
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""" |
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if self.is_tag_available(tag): |
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self.endpoint_a.use_tag(tag) |
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self.endpoint_b.use_tag(tag) |
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return True |
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return False |
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def is_tag_available(self, tag): |
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"""Check if a tag is available.""" |
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return (self.endpoint_a.is_tag_available(tag) and |
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self.endpoint_b.is_tag_available(tag)) |
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def get_next_available_tag(self): |
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"""Return the next available tag if exists.""" |
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# Copy the available tags because in case of error |
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# we will remove and add elements to the available_tags |
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available_tags_a = self.endpoint_a.available_tags.copy() |
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available_tags_b = self.endpoint_b.available_tags.copy() |
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random.shuffle(available_tags_a) |
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random.shuffle(available_tags_b) |
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for tag in available_tags_a: |
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# Tag does not exist in endpoint B. Try another tag. |
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if tag not in available_tags_b: |
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continue |
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# Tag already in use. Try another tag. |
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if not self.endpoint_a.use_tag(tag): |
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continue |
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# Tag already in use in B. Mark the tag as available again. |
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if not self.endpoint_b.use_tag(tag): |
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self.endpoint_a.make_tag_available(tag) |
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continue |
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# Tag used successfully by both endpoints. Returning. |
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return tag |
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raise KytosNoTagAvailableError(self) |
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def make_tag_available(self, tag): |
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"""Add a specific tag in available_tags.""" |
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if not self.is_tag_available(tag): |
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self.endpoint_a.make_tag_available(tag) |
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self.endpoint_b.make_tag_available(tag) |
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return True |
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return False |
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def available_vlans(self): |
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"""Get all available vlans from each interface in the link.""" |
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vlans_a = self._get_available_vlans(self.endpoint_a) |
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vlans_b = self._get_available_vlans(self.endpoint_b) |
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return [vlan for vlan in vlans_a if vlan in vlans_b] |
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@staticmethod |
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def _get_available_vlans(endpoint): |
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"""Return all vlans from endpoint.""" |
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tags = endpoint.available_tags |
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return [tag for tag in tags if tag.tag_type == TAGType.VLAN] |
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def as_dict(self): |
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"""Return the Link as a dictionary.""" |
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return {'id': self.id, |
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'endpoint_a': self.endpoint_a.as_dict(), |
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'endpoint_b': self.endpoint_b.as_dict(), |
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'metadata': self.get_metadata_as_dict(), |
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'active': self.is_active(), |
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'enabled': self.is_enabled()} |
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def as_json(self): |
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"""Return the Link as a JSON string.""" |
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return json.dumps(self.as_dict()) |
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kytos /
kytos
