"""Manage host learning on VLANs."""
# Copyright (C) 2013 Nippon Telegraph and Telephone Corporation.
# Copyright (C) 2015 Brad Cowie, Christopher Lorier and Joe Stringer.
# Copyright (C) 2015 Research and Education Advanced Network New Zealand Ltd.
# Copyright (C) 2015--2018 The Contributors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import random
from faucet import valve_of
[docs]class ValveHostManager:
"""Manage host learning on VLANs."""
def __init__(self, logger, ports, vlans, eth_src_table, eth_dst_table,
learn_timeout, learn_jitter, learn_ban_timeout,
low_priority, host_priority,
cache_update_guard_time):
self.logger = logger
self.ports = ports
self.vlans = vlans
self.eth_src_table = eth_src_table
self.eth_dst_table = eth_dst_table
self.learn_timeout = learn_timeout
self.learn_jitter = learn_jitter
self.learn_ban_timeout = learn_ban_timeout
self.low_priority = low_priority
self.host_priority = host_priority
self.cache_update_guard_time = cache_update_guard_time
[docs] def ban_rules(self, pkt_meta):
"""Limit learning to a maximum configured on this port/VLAN.
Args:
pkt_meta: PacketMeta instance.
Returns:
list: OpenFlow messages, if any.
"""
ofmsgs = []
port = pkt_meta.port
eth_src = pkt_meta.eth_src
vlan = pkt_meta.vlan
entry = vlan.cached_host(eth_src)
if entry is None:
if port.max_hosts:
if port.hosts_count() == port.max_hosts:
ofmsgs.append(self._temp_ban_host_learning(self.eth_src_table.match(in_port=port.number)))
port.dyn_learn_ban_count += 1
self.logger.info(
'max hosts %u reached on %s, '
'temporarily banning learning on this port, '
'and not learning %s' % (
port.max_hosts, port, eth_src))
if vlan is not None and vlan.max_hosts:
hosts_count = vlan.hosts_count()
if hosts_count == vlan.max_hosts:
ofmsgs.append(self._temp_ban_host_learning(self.eth_src_table.match(vlan=vlan)))
vlan.dyn_learn_ban_count += 1
self.logger.info(
'max hosts %u reached on VLAN %u, '
'temporarily banning learning on this vlan, '
'and not learning %s on %s' % (
vlan.max_hosts, vlan.vid, eth_src, port))
return ofmsgs
def _temp_ban_host_learning(self, match):
return self.eth_src_table.flowdrop(
match,
priority=(self.low_priority + 1),
hard_timeout=self.learn_ban_timeout)
[docs] def delete_host_from_vlan(self, eth_src, vlan):
"""Delete a host from a VLAN."""
ofmsgs = []
ofmsgs.extend(self.eth_src_table.flowdel(
self.eth_src_table.match(vlan=vlan, eth_src=eth_src)))
ofmsgs.extend(self.eth_dst_table.flowdel(
self.eth_dst_table.match(vlan=vlan, eth_dst=eth_src)))
return ofmsgs
[docs] def expire_hosts_from_vlan(self, vlan, now):
"""Expire hosts from VLAN cache."""
expired_hosts = vlan.expire_cache_hosts(now, self.learn_timeout)
if expired_hosts:
vlan.dyn_last_time_hosts_expired = now
self.logger.info(
'%u recently active hosts on VLAN %u, expired %s' % (
vlan.hosts_count(), vlan.vid, expired_hosts))
return expired_hosts
def _jitter_learn_timeout(self):
"""Calculate jittered learning timeout to avoid synchronized host timeouts."""
return int(max(abs(
self.learn_timeout -
(self.learn_jitter / 2) + random.randint(0, self.learn_jitter)),
self.cache_update_guard_time))
[docs] def learn_host_timeouts(self, port):
"""Calculate flow timeouts for learning on a port."""
# hosts learned on this port never relearned
if port.permanent_learn:
learn_timeout = 0
else:
learn_timeout = self.learn_timeout
if self.learn_timeout:
learn_timeout = self._jitter_learn_timeout()
# Update datapath to no longer send packets from this mac to controller
# note the use of hard_timeout here and idle_timeout for the dst table
# this is to ensure that the source rules will always be deleted before
# any rules on the dst table. Otherwise if the dst table rule expires
# but the src table rule is still being hit intermittantly the switch
# will flood packets to that dst and not realise it needs to relearn
# the rule
# NB: Must be lower than highest priority otherwise it can match
# flows destined to controller
src_rule_idle_timeout = 0
src_rule_hard_timeout = learn_timeout
dst_rule_idle_timeout = learn_timeout
return (src_rule_idle_timeout, src_rule_hard_timeout, dst_rule_idle_timeout)
[docs] def learn_host_on_vlan_port_flows(self, port, vlan, eth_src, delete_existing,
src_rule_idle_timeout, src_rule_hard_timeout,
dst_rule_idle_timeout):
"""Return flows that implement learning a host on a port."""
ofmsgs = []
if port.permanent_learn:
# Antispoofing rule for this MAC.
ofmsgs.append(self.eth_src_table.flowdrop(
self.eth_src_table.match(vlan=vlan, eth_src=eth_src),
priority=(self.host_priority - 2)))
else:
# Delete any existing entries for MAC.
if delete_existing:
ofmsgs.extend(self.delete_host_from_vlan(eth_src, vlan))
# Output packets for this MAC to specified port.
ofmsgs.append(self.eth_dst_table.flowmod(
self.eth_dst_table.match(vlan=vlan, eth_dst=eth_src),
priority=self.host_priority,
inst=[valve_of.apply_actions(vlan.output_port(port))],
idle_timeout=dst_rule_idle_timeout))
# Associate this MAC with source port.
src_match = self.eth_src_table.match(
in_port=port.number, vlan=vlan, eth_src=eth_src)
src_priority = self.host_priority - 1
inst = valve_of.goto_table(self.eth_dst_table)
if port.override_output_port:
inst = valve_of.apply_actions([
valve_of.output_port(port.override_output_port.number)])
ofmsgs.append(self.eth_src_table.flowmod(
match=src_match,
priority=src_priority,
inst=[inst],
hard_timeout=src_rule_hard_timeout,
idle_timeout=src_rule_idle_timeout))
# If port is in hairpin mode, install a special rule
# that outputs packets destined to this MAC back out the same
# port they came in (e.g. multiple hosts on same WiFi AP,
# and FAUCET is switching between them on the same port).
if port.hairpin:
ofmsgs.append(self.eth_src_table.flowmod(
self.eth_src_table.match(in_port=port.number, vlan=vlan, eth_dst=eth_src),
priority=(self.host_priority + 1),
inst=[valve_of.apply_actions(vlan.output_port(port, hairpin=True))],
hard_timeout=src_rule_hard_timeout,
idle_timeout=dst_rule_idle_timeout))
return ofmsgs
[docs] def learn_host_on_vlan_ports(self, now, port, vlan, eth_src,
delete_existing=True,
last_dp_coldstart_time=None):
"""Learn a host on a port."""
ofmsgs = []
cache_port = None
cache_age = None
entry = vlan.cached_host(eth_src)
# Host not cached, and no hosts expired since we cold started
# Enable faster learning by assuming there's no previous host to delete
if entry is None:
if (last_dp_coldstart_time and
(vlan.dyn_last_time_hosts_expired is None or
vlan.dyn_last_time_hosts_expired < last_dp_coldstart_time)):
delete_existing = False
else:
cache_age = now - entry.cache_time
cache_port = entry.port
same_lag = (
cache_port is not None and
cache_port.lacp and port.lacp and cache_port.lacp == port.lacp)
if cache_port == port or same_lag:
# skip delete if host didn't change ports or on same LAG.
delete_existing = False
# if we very very recently learned this host, don't do anything.
if cache_age < self.cache_update_guard_time:
return (ofmsgs, cache_port)
if port.loop_protect:
ban_age = None
learn_ban = False
# if recently in loop protect mode and still receiving packets,
# prolong the ban
if port.dyn_last_ban_time:
ban_age = now - port.dyn_last_ban_time
if ban_age < self.cache_update_guard_time:
learn_ban = True
# if not in protect mode and we get a rapid move, enact protect mode
if not learn_ban and entry is not None:
if port != cache_port and cache_age < self.cache_update_guard_time:
learn_ban = True
port.dyn_learn_ban_count += 1
self.logger.info('rapid move of %s from %s to %s, temp loop ban %s' % (
eth_src, cache_port, port, port))
# already, or newly in protect mode, apply the ban rules.
if learn_ban:
port.dyn_last_ban_time = now
ofmsgs.append(self._temp_ban_host_learning(self.eth_src_table.match(in_port=port.number)))
return (ofmsgs, cache_port)
(src_rule_idle_timeout,
src_rule_hard_timeout,
dst_rule_idle_timeout) = self.learn_host_timeouts(port)
ofmsgs.extend(self.learn_host_on_vlan_port_flows(
port, vlan, eth_src, delete_existing,
src_rule_idle_timeout, src_rule_hard_timeout,
dst_rule_idle_timeout))
vlan.add_cache_host(eth_src, port, now)
return (ofmsgs, cache_port)
[docs] def flow_timeout(self, _now, _table_id, _match):
"""Handle a flow timed out message from dataplane."""
return []
[docs]class ValveHostFlowRemovedManager(ValveHostManager):
"""Trigger relearning on flow removed notifications.
.. note::
not currently reliable.
"""
[docs] def flow_timeout(self, now, table_id, match):
ofmsgs = []
if table_id in (self.eth_src_table.table_id, self.eth_dst_table.table_id):
if 'vlan_vid' in match:
vlan = self.vlans[valve_of.devid_present(match['vlan_vid'])]
in_port = None
eth_src = None
eth_dst = None
for field, value in list(match.items()):
if field == 'in_port':
in_port = value
elif field == 'eth_src':
eth_src = value
elif field == 'eth_dst':
eth_dst = value
if eth_src and in_port:
port = self.ports[in_port]
ofmsgs.extend(self._src_rule_expire(vlan, port, eth_src))
elif eth_dst:
ofmsgs.extend(self._dst_rule_expire(now, vlan, eth_dst))
return ofmsgs
[docs] def expire_hosts_from_vlan(self, _vlan, _now):
return []
[docs] def learn_host_timeouts(self, port):
"""Calculate flow timeouts for learning on a port."""
# hosts learned on this port never relearned
if port.permanent_learn:
learn_timeout = 0
else:
learn_timeout = self._jitter_learn_timeout()
# Disable hard_time, dst rule expires after src rule.
src_rule_idle_timeout = learn_timeout
src_rule_hard_timeout = 0
dst_rule_idle_timeout = learn_timeout + self.cache_update_guard_time
return (src_rule_idle_timeout, src_rule_hard_timeout, dst_rule_idle_timeout)
def _src_rule_expire(self, vlan, port, eth_src):
"""When a src rule expires, the host is probably inactive or active in
receiving but not sending. We mark just mark the host as expired."""
ofmsgs = []
entry = vlan.cached_host_on_port(eth_src, port)
if entry is not None:
vlan.expire_cache_host(eth_src)
self.logger.info('expired src_rule for host %s' % eth_src)
return ofmsgs
def _dst_rule_expire(self, now, vlan, eth_dst):
"""Expiring a dst rule may indicate that the host is actively sending
traffic but not receving. If the src rule not yet expires, we reinstall
host rules."""
ofmsgs = []
entry = vlan.cached_host(eth_dst)
if entry is not None:
ofmsgs.extend(self.learn_host_on_vlan_ports(
now, entry.port, vlan, eth_dst, delete_existing=False))
self.logger.info(
'refreshing host %s from VLAN %u' % (eth_dst, vlan.vid))
return ofmsgs