os-ken/ryu/services/protocols/bgp/speaker.py
IWAMOTO Toshihiro 536a42d8c1 python3: Use b'str' for binary literals
Signed-off-by: IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
2015-06-25 12:23:31 +09:00

587 lines
22 KiB
Python

# Copyright (C) 2014 Nippon Telegraph and Telephone Corporation.
#
# 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.
"""
BGP protocol implementation.
"""
import logging
import socket
import struct
import traceback
from socket import IPPROTO_TCP, TCP_NODELAY
from eventlet import semaphore
from ryu.lib.packet import bgp
from ryu.lib.packet.bgp import RouteFamily
from ryu.lib.packet.bgp import RF_RTC_UC
from ryu.lib.packet.bgp import BGPMessage
from ryu.lib.packet.bgp import BGPOpen
from ryu.lib.packet.bgp import BGPUpdate
from ryu.lib.packet.bgp import BGPKeepAlive
from ryu.lib.packet.bgp import BGPNotification
from ryu.lib.packet.bgp import BGPRouteRefresh
from ryu.lib.packet.bgp import BGP_MSG_OPEN
from ryu.lib.packet.bgp import BGP_MSG_UPDATE
from ryu.lib.packet.bgp import BGP_MSG_KEEPALIVE
from ryu.lib.packet.bgp import BGP_MSG_NOTIFICATION
from ryu.lib.packet.bgp import BGP_MSG_ROUTE_REFRESH
from ryu.lib.packet.bgp import BGP_CAP_ENHANCED_ROUTE_REFRESH
from ryu.lib.packet.bgp import BGP_CAP_MULTIPROTOCOL
from ryu.lib.packet.bgp import BGP_CAP_ROUTE_REFRESH
from ryu.lib.packet.bgp import BGP_ERROR_HOLD_TIMER_EXPIRED
from ryu.lib.packet.bgp import BGP_ERROR_SUB_HOLD_TIMER_EXPIRED
from ryu.lib.packet.bgp import get_rf
from ryu.services.protocols.bgp.base import Activity
from ryu.services.protocols.bgp.base import add_bgp_error_metadata
from ryu.services.protocols.bgp.base import BGPSException
from ryu.services.protocols.bgp.base import CORE_ERROR_CODE
from ryu.services.protocols.bgp.constants import BGP_FSM_CONNECT
from ryu.services.protocols.bgp.constants import BGP_FSM_OPEN_CONFIRM
from ryu.services.protocols.bgp.constants import BGP_FSM_OPEN_SENT
from ryu.services.protocols.bgp.constants import BGP_VERSION_NUM
from ryu.services.protocols.bgp.protocol import Protocol
from ryu.services.protocols.bgp.utils.validation import is_valid_old_asn
LOG = logging.getLogger('bgpspeaker.speaker')
# BGP min. and max. message lengths as per RFC.
BGP_MIN_MSG_LEN = 19
BGP_MAX_MSG_LEN = 4096
# Keep-alive singleton.
_KEEP_ALIVE = BGPKeepAlive()
@add_bgp_error_metadata(code=CORE_ERROR_CODE, sub_code=2,
def_desc='Unknown error occurred related to Speaker.')
class BgpProtocolException(BGPSException):
"""Base exception related to peer connection management.
"""
pass
def nofitication_factory(code, subcode):
"""Returns a `Notification` message corresponding to given codes.
Parameters:
- `code`: (int) BGP error code
- `subcode`: (int) BGP error sub-code
"""
notification = BGPNotification(code, subcode)
if not notification.reason:
raise ValueError('Invalid code/sub-code.')
return notification
class BgpProtocol(Protocol, Activity):
"""Protocol that handles BGP messages.
"""
MESSAGE_MARKER = (b'\xff\xff\xff\xff\xff\xff\xff\xff'
b'\xff\xff\xff\xff\xff\xff\xff\xff')
def __init__(self, socket, signal_bus, is_reactive_conn=False):
# Validate input.
if socket is None:
raise ValueError('Invalid arguments passed.')
self._remotename = self.get_remotename(socket)
self._localname = self.get_localname(socket)
activity_name = ('BgpProtocol %s, %s, %s' % (is_reactive_conn,
self._remotename,
self._localname))
Activity.__init__(self, name=activity_name)
# Intialize instance variables.
self._peer = None
self._recv_buff = ''
self._socket = socket
self._socket.setsockopt(IPPROTO_TCP, TCP_NODELAY, 1)
self._sendlock = semaphore.Semaphore()
self._signal_bus = signal_bus
self._holdtime = None
self._keepalive = None
self._expiry = None
# Add socket to Activity's socket container for managing it.
if is_reactive_conn:
self._asso_socket_map['passive_conn'] = self._socket
else:
self._asso_socket_map['active_conn'] = self._socket
self._open_msg = None
self.state = BGP_FSM_CONNECT
self._is_reactive = is_reactive_conn
self.sent_open_msg = None
self.recv_open_msg = None
self._is_bound = False
@property
def is_reactive(self):
return self._is_reactive
@property
def holdtime(self):
return self._holdtime
@property
def keepalive(self):
return self._keepalive
def is_colliding(self, other_protocol):
if not isinstance(other_protocol, BgpProtocol):
raise ValueError('Currently only support comparing with '
'`BgpProtocol`')
# Compare protocol connection end point's addresses
if (self._remotename[0] == other_protoco._remotename[0] and
self._localname[0] == other_protocol._localname[0]):
return True
return False
def is_local_router_id_greater(self):
"""Compares *True* if local router id is greater when compared to peer
bgp id.
Should only be called after protocol has reached OpenConfirm state.
"""
from ryu.services.protocols.bgp.utils.bgp import from_inet_ptoi
if not self.state == BGP_FSM_OPEN_CONFIRM:
raise BgpProtocolException(desc='Can access remote router id only'
' after open message is received')
remote_id = self.recv_open_msg.bgp_identifier
local_id = self.sent_open_msg.bgp_identifier
return from_inet_ptoi(local_id) > from_inet_ptoi(remote_id)
def is_enhanced_rr_cap_valid(self):
"""Checks is enhanced route refresh capability is enabled/valid.
Checks sent and received `Open` messages to see if this session with
peer is capable of enhanced route refresh capability.
"""
if not self.recv_open_msg:
raise ValueError('Did not yet receive peers open message.')
err_cap_enabled = False
local_caps = self.sent_open_msg.opt_param
peer_caps = self.recv_open_msg.opt_param
local_cap = [cap for cap in local_caps
if cap.cap_code == BGP_CAP_ENHANCED_ROUTE_REFRESH]
peer_cap = [cap for cap in peer_caps
if cap.cap_code == BGP_CAP_ENHANCED_ROUTE_REFRESH]
# Both local and peer should advertise ERR capability for it to be
# enabled.
if local_cap and peer_cap:
err_cap_enabled = True
return err_cap_enabled
def _check_route_fmly_adv(self, open_msg, route_family):
match_found = False
local_caps = open_msg.opt_param
for cap in local_caps:
# Check MP_BGP capability was advertised.
if cap.cap_code == BGP_CAP_MULTIPROTOCOL:
# Iterate over all advertised mp_bgp caps to find a match.
if (route_family.afi == cap.afi and
route_family.safi == cap.safi):
match_found = True
return match_found
def is_route_family_adv(self, route_family):
"""Checks if `route_family` was advertised to peer as per MP_BGP cap.
Returns:
- True: if given address family was advertised.
- False: if given address family was not advertised.
"""
return self._check_route_fmly_adv(self.sent_open_msg, route_family)
def is_route_family_adv_recv(self, route_family):
"""Checks if `route_family` was advertised by peer as per MP_BGP cap.
Returns:
- True: if given address family was advertised.
- False: if given address family was not advertised.
"""
return self._check_route_fmly_adv(self.recv_open_msg, route_family)
@property
def negotiated_afs(self):
local_caps = self.sent_open_msg.opt_param
remote_caps = self.recv_open_msg.opt_param
local_mbgp_cap = [cap for cap in local_caps
if cap.cap_code == BGP_CAP_MULTIPROTOCOL]
remote_mbgp_cap = [cap for cap in remote_caps
if cap.cap_code == BGP_CAP_MULTIPROTOCOL]
# Check MP_BGP capabilities were advertised.
if local_mbgp_cap and remote_mbgp_cap:
local_families = set([
(peer_cap.afi, peer_cap.safi)
for peer_cap in local_mbgp_cap
])
remote_families = set([
(peer_cap.afi, peer_cap.safi)
for peer_cap in remote_mbgp_cap
])
afi_safi = local_families.intersection(remote_families)
else:
afi_safi = set()
afs = []
for afi, safi in afi_safi:
afs.append(get_rf(afi, safi))
return afs
def is_mbgp_cap_valid(self, route_family):
"""Returns true if both sides of this protocol have advertise
capability for this address family.
"""
return (self.is_route_family_adv(route_family) and
self.is_route_family_adv_recv(route_family))
def _run(self, peer):
"""Sends open message to peer and handles received messages.
Parameters:
- `peer`: the peer to which this protocol instance is connected to.
"""
# We know the peer we are connected to, we send open message.
self._peer = peer
self.connection_made()
# We wait for peer to send messages.
self._recv_loop()
def data_received(self, next_bytes):
try:
self._data_received(next_bytes)
except bgp.BgpExc as exc:
LOG.error(
"BGPExc Exception while receiving data: "
"%s \n Traceback %s \n"
% (str(exc), traceback.format_exc())
)
if exc.SEND_ERROR:
self.send_notification(exc.CODE, exc.SUB_CODE)
else:
self._socket.close()
raise exc
@staticmethod
def parse_msg_header(buff):
"""Parses given `buff` into bgp message header format.
Returns a tuple of marker, length, type of bgp message.
"""
return struct.unpack('!16sHB', buff)
def _data_received(self, next_bytes):
"""Maintains buffer of bytes received from peer and extracts bgp
message from this buffer if enough data is received.
Validates bgp message marker, length, type and data and constructs
appropriate bgp message instance and calls handler.
:Parameters:
- `next_bytes`: next set of bytes received from peer.
"""
# Append buffer with received bytes.
self._recv_buff += next_bytes
while True:
# If current buffer size is less then minimum bgp message size, we
# return as we do not have a complete bgp message to work with.
if len(self._recv_buff) < BGP_MIN_MSG_LEN:
return
# Parse message header into elements.
auth, length, ptype = BgpProtocol.parse_msg_header(
self._recv_buff[:BGP_MIN_MSG_LEN])
# Check if we have valid bgp message marker.
# We should get default marker since we are not supporting any
# authentication.
if (auth != BgpProtocol.MESSAGE_MARKER):
LOG.error('Invalid message marker received: %s', auth)
raise bgp.NotSync()
# Check if we have valid bgp message length.
check = lambda: length < BGP_MIN_MSG_LEN\
or length > BGP_MAX_MSG_LEN
# RFC says: The minimum length of the OPEN message is 29
# octets (including the message header).
check2 = lambda: ptype == BGP_MSG_OPEN\
and length < BGPOpen._MIN_LEN
# RFC says: A KEEPALIVE message consists of only the
# message header and has a length of 19 octets.
check3 = lambda: ptype == BGP_MSG_KEEPALIVE\
and length != BGPKeepAlive._MIN_LEN
# RFC says: The minimum length of the UPDATE message is 23
# octets.
check4 = lambda: ptype == BGP_MSG_UPDATE\
and length < BGPUpdate._MIN_LEN
if check() or check2() or check3() or check4():
raise bgp.BadLen(ptype, length)
# If we have partial message we wait for rest of the message.
if len(self._recv_buff) < length:
return
msg, rest = BGPMessage.parser(self._recv_buff)
self._recv_buff = rest
# If we have a valid bgp message we call message handler.
self._handle_msg(msg)
def send_notification(self, code, subcode):
"""Utility to send notification message.
Closes the socket after sending the message.
:Parameters:
- `socket`: (socket) - socket over which to send notification
message.
- `code`: (int) - BGP Notification code
- `subcode`: (int) - BGP Notification sub-code
RFC ref: http://tools.ietf.org/html/rfc4486
http://www.iana.org/assignments/bgp-parameters/bgp-parameters.xhtml
"""
notification = BGPNotification(code, subcode)
reason = notification.reason
self._send_with_lock(notification)
self._signal_bus.bgp_error(self._peer, code, subcode, reason)
if len(self._localname):
LOG.error('Sent notification to %r >> %s', self._localname,
notification)
self._socket.close()
def _send_with_lock(self, msg):
self._sendlock.acquire()
try:
self._socket.sendall(msg.serialize())
except socket.error as err:
self.connection_lost('failed to write to socket')
finally:
self._sendlock.release()
def send(self, msg):
if not self.started:
raise BgpProtocolException('Tried to send message to peer when '
'this protocol instance is not started'
' or is no longer is started state.')
self._send_with_lock(msg)
if msg.type == BGP_MSG_NOTIFICATION:
LOG.error('Sent notification to %s >> %s', self._remotename, msg)
self._signal_bus.bgp_notification_sent(self._peer, msg)
else:
LOG.debug('Sent msg to %s >> %s', self._remotename, msg)
def stop(self):
Activity.stop(self)
def _validate_open_msg(self, open_msg):
"""Validates BGP OPEN message according from application context.
Parsing modules takes care of validating OPEN message that need no
context. But here we validate it according to current application
settings. RTC or RR/ERR are MUST capability if peer does not support
either one of them we have to end session.
"""
assert open_msg.type == BGP_MSG_OPEN
# Validate remote ASN.
remote_asnum = open_msg.my_as
# Since 4byte AS is not yet supported, we validate AS as old style AS.
if (not is_valid_old_asn(remote_asnum) or
remote_asnum != self._peer.remote_as):
raise bgp.BadPeerAs()
# Validate bgp version number.
if open_msg.version != BGP_VERSION_NUM:
raise bgp.UnsupportedVersion(BGP_VERSION_NUM)
def _handle_msg(self, msg):
"""When a BGP message is received, send it to peer.
Open messages are validated here. Peer handler is called to handle each
message except for *Open* and *Notification* message. On receiving
*Notification* message we close connection with peer.
"""
LOG.debug('Received msg from %s << %s', self._remotename, msg)
# If we receive open message we try to bind to protocol
if (msg.type == BGP_MSG_OPEN):
if self.state == BGP_FSM_OPEN_SENT:
# Validate open message.
self._validate_open_msg(msg)
self.recv_open_msg = msg
self.state = BGP_FSM_OPEN_CONFIRM
self._peer.state.bgp_state = self.state
# Try to bind this protocol to peer.
self._is_bound = self._peer.bind_protocol(self)
# If this protocol failed to bind to peer.
if not self._is_bound:
# Failure to bind to peer indicates connection collision
# resolution choose different instance of protocol and this
# instance has to close. Before closing it sends
# appropriate notification msg. to peer.
raise bgp.CollisionResolution()
# If peer sends Hold Time as zero, then according to RFC we do
# not set Hold Time and Keep Alive timer.
if msg.hold_time == 0:
LOG.info('The Hold Time sent by the peer is zero, hence '
'not setting any Hold Time and Keep Alive'
' timers.')
else:
# Start Keep Alive timer considering Hold Time preference
# of the peer.
self._start_timers(msg.hold_time)
self._send_keepalive()
# Peer does not see open message.
return
else:
# If we receive a Open message out of order
LOG.error('Open message received when current state is not '
'OpenSent')
# Received out-of-order open message
# We raise Finite state machine error
raise bgp.FiniteStateMachineError()
elif msg.type == BGP_MSG_NOTIFICATION:
if self._peer:
self._signal_bus.bgp_notification_received(self._peer, msg)
# If we receive notification message
LOG.error('Received notification message, hence closing '
'connection %s', msg)
self._socket.close()
return
# If we receive keepalive or update message, we reset expire timer.
if (msg.type == BGP_MSG_KEEPALIVE or
msg.type == BGP_MSG_UPDATE):
if self._expiry:
self._expiry.reset()
# Call peer message handler for appropriate messages.
if (msg.type in
(BGP_MSG_UPDATE, BGP_MSG_KEEPALIVE, BGP_MSG_ROUTE_REFRESH)):
self._peer.handle_msg(msg)
# We give chance to other threads to run.
self.pause(0)
def _start_timers(self, peer_holdtime):
"""Starts keepalive and expire timers.
Hold time is set to min. of peer and configured/default hold time.
Starts keep alive timer and expire timer based on this value.
"""
neg_timer = min(self._holdtime, peer_holdtime)
if neg_timer < self._holdtime:
LOG.info('Negotiated hold time (%s) is lower then '
'configured/default (%s).', neg_timer, self._holdtime)
# We use negotiated timer value.
self._holdtime = neg_timer
self._keepalive = self._create_timer('Keepalive Timer',
self._send_keepalive)
interval = self._holdtime // 3
self._keepalive.start(interval, now=False)
# Setup the expire timer.
self._expiry = self._create_timer('Holdtime Timer', self._expired)
self._expiry.start(self._holdtime, now=False)
LOG.debug('Started keep-alive and expire timer for negotiated hold'
'time %s', self._holdtime)
def _expired(self):
"""Hold timer expired event handler.
"""
LOG.info('Negotiated hold time %s expired.', self._holdtime)
code = BGP_ERROR_HOLD_TIMER_EXPIRED
subcode = BGP_ERROR_SUB_HOLD_TIMER_EXPIRED
self.send_notification(code, subcode)
self.connection_lost('Negotiated hold time %s expired.' %
self._holdtime)
self.stop()
def _send_keepalive(self):
self.send(_KEEP_ALIVE)
def _recv_loop(self):
"""Sits in tight loop collecting data received from peer and
processing it.
"""
required_len = BGP_MIN_MSG_LEN
conn_lost_reason = "Connection lost as protocol is no longer active"
try:
while True:
next_bytes = self._socket.recv(required_len)
if len(next_bytes) == 0:
conn_lost_reason = 'Peer closed connection'
break
self.data_received(next_bytes)
except socket.error as err:
conn_lost_reason = 'Connection to peer lost: %s.' % err
except bgp.BgpExc as ex:
conn_lost_reason = 'Connection to peer lost, reason: %s.' % ex
except Exception as e:
LOG.debug(traceback.format_exc())
conn_lost_reason = str(e)
finally:
self.connection_lost(conn_lost_reason)
def connection_made(self):
"""Connection to peer handler.
We send bgp open message to peer and intialize related attributes.
"""
assert self.state == BGP_FSM_CONNECT
# We have a connection with peer we send open message.
open_msg = self._peer.create_open_msg()
self._holdtime = open_msg.hold_time
self.state = BGP_FSM_OPEN_SENT
if not self.is_reactive:
self._peer.state.bgp_state = self.state
self.sent_open_msg = open_msg
self.send(open_msg)
self._peer.connection_made()
def connection_lost(self, reason):
"""Stops all timers and notifies peer that connection is lost.
"""
if self._peer:
state = self._peer.state.bgp_state
if self._is_bound or state == BGP_FSM_OPEN_SENT:
self._peer.connection_lost(reason)
self._peer = None
if reason:
LOG.info(reason)
else:
LOG.info('Connection to peer closed for unknown reasons.')