/usr/share/arc/ssm/ssm2.py is in nordugrid-arc-arex 5.3.0~rc1-1.
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Copyright (C) 2012 STFC
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.
@author: Will Rogers
'''
# It's possible for SSM to be used without SSL, and the ssl module isn't in the
# standard library until 2.6, so this makes it safe for earlier Python versions.
try:
import ssl
except ImportError:
# ImportError is raised later on if SSL is actually requested.
ssl = None
import crypto
from dirq.QueueSimple import QueueSimple
from dirq.queue import Queue
import stomp
# Exception changed name between stomppy versions
try:
from stomp.exception import ConnectFailedException
except ImportError:
from stomp.exception import ReconnectFailedException \
as ConnectFailedException
import os
import socket
import time
import logging
# Set up logging
log = logging.getLogger(__name__)
class Ssm2Exception(Exception):
'''
Exception for use by SSM2.
'''
pass
class Ssm2(stomp.ConnectionListener):
'''
Minimal SSM implementation.
'''
# Schema for the dirq message queue.
QSCHEMA = {'body': 'string', 'signer':'string', 'empaid':'string?'}
REJECT_SCHEMA = {'body': 'string', 'signer':'string?', 'empaid':'string?', 'error':'string'}
CONNECTION_TIMEOUT = 10
def __init__(self, hosts_and_ports, qpath, cert, key, dest=None, listen=None,
capath=None, check_crls=False, use_ssl=False, username=None, password=None,
enc_cert=None, verify_enc_cert=True, pidfile=None):
'''
Creates an SSM2 object. If a listen value is supplied,
this SSM2 will be a receiver.
'''
self._conn = None
self._last_msg = None
self._brokers = hosts_and_ports
self._cert = cert
self._key = key
self._enc_cert = enc_cert
self._capath = capath
self._check_crls = check_crls
self._user = username
self._pwd = password
self._use_ssl = use_ssl
# use pwd auth if we're supplied both user and pwd
self._use_pwd = username is not None and password is not None
self.connected = False
self._listen = listen
self._dest = dest
self._valid_dns = []
self._pidfile = pidfile
# create the filesystem queues for accepted and rejected messages
if dest is not None and listen is None:
self._outq = QueueSimple(qpath)
elif listen is not None:
inqpath = os.path.join(qpath, 'incoming')
rejectqpath = os.path.join(qpath, 'reject')
self._inq = Queue(inqpath, schema=Ssm2.QSCHEMA)
self._rejectq = Queue(rejectqpath, schema=Ssm2.REJECT_SCHEMA)
else:
raise Ssm2Exception('SSM must be either producer or consumer.')
# check that the cert and key match
if not crypto.check_cert_key(self._cert, self._key):
raise Ssm2Exception('Cert and key don\'t match.')
# check the server certificate provided
if enc_cert is not None:
log.info('Messages will be encrypted using %s', enc_cert)
if not os.path.isfile(self._enc_cert):
raise Ssm2Exception('Specified certificate file does not exist: %s.' % self._enc_cert)
if verify_enc_cert:
if not crypto.verify_cert_path(self._enc_cert, self._capath, self._check_crls):
raise Ssm2Exception('Failed to verify server certificate %s against CA path %s.'
% (self._enc_cert, self._capath))
def set_dns(self, dn_list):
'''
Set the list of DNs which are allowed to sign incoming messages.
'''
self._valid_dns = dn_list
##########################################################################
# Methods called by stomppy
##########################################################################
def on_send(self, headers, unused_body):
'''
Called by stomppy when a message is sent.
'''
log.debug('Sent message: ' + headers['empa-id'])
def on_message(self, headers, body):
'''
Called by stomppy when a message is received.
Handle the message according to its content and headers.
'''
try:
empaid = headers['empa-id']
if empaid == 'ping': # ignore ping message
log.info('Received ping message.')
return
except KeyError:
empaid = 'noid'
log.info('Received message: ' + empaid)
raw_msg, signer = self._handle_msg(body)
try:
if raw_msg is None: # the message has been rejected
log.warn('Message rejected.')
if signer is None: # crypto failed
err_msg = 'Could not extract message.'
log.warn(err_msg)
signer = 'Not available.'
else: # crypto ok but signer not verified
err_msg = 'Signer not in valid DNs list.'
log.warn(err_msg)
self._rejectq.add({'body': body,
'signer': signer,
'empaid': empaid,
'error': err_msg})
else: # message verified ok
self._inq.add({'body': raw_msg,
'signer':signer,
'empaid': headers['empa-id']})
except OSError, e:
log.error('Failed to read or write file: %s', e)
def on_error(self, unused_headers, body):
'''
Called by stomppy when an error frame is received.
'''
log.warn('Error message received: %s', body)
raise Ssm2Exception()
def on_connected(self, unused_headers, unused_body):
'''
Called by stomppy when a connection is established.
Track the connection.
'''
self.connected = True
log.info('Connected.')
def on_disconnected(self):
'''
Called by stomppy when disconnected from the broker.
'''
log.info('Disconnected from broker.')
self.connected = False
def on_receipt(self, headers, unused_body):
'''
Called by stomppy when the broker acknowledges receipt of a message.
'''
log.info('Broker received message: ' + headers['receipt-id'])
self._last_msg = headers['receipt-id']
##########################################################################
# Message handling methods
##########################################################################
def _handle_msg(self, text):
'''
Deal with the raw message contents appropriately:
- decrypt if necessary
- verify signature
Return plain-text message and signer's DN.
'''
if text is None or text == '':
return None, None
# if not text.startswith('MIME-Version: 1.0'):
# raise Ssm2Exception('Not a valid message.')
# encrypted - this could be nicer
if 'application/pkcs7-mime' in text or 'application/x-pkcs7-mime' in text:
try:
text = crypto.decrypt(text, self._cert, self._key)
except crypto.CryptoException, e:
log.error('Failed to decrypt message: %s', e)
return None, None
# always signed
try:
message, signer = crypto.verify(text, self._capath, self._check_crls)
except crypto.CryptoException, e:
log.error('Failed to verify message: %s', e)
return None, None
if signer not in self._valid_dns:
log.error('Message signer not in the valid DNs list: %s', signer)
return None, signer
else:
log.info('Valid signer: %s', signer)
return message, signer
def _send_msg(self, message, msgid):
'''
Send one message using stomppy. The message will be signed using
the host cert and key. If an encryption certificate
has been supplied, the message will also be encrypted.
'''
log.info('Sending message: ' + msgid)
headers = {'destination': self._dest, 'receipt': msgid,
'empa-id': msgid}
if message is not None:
to_send = crypto.sign(message, self._cert, self._key)
if self._enc_cert is not None:
to_send = crypto.encrypt(to_send, self._enc_cert)
else:
to_send = ''
self._conn.send(to_send, headers=headers)
def send_ping(self):
'''
If a STOMP connection is left open with no activity for an hour or
so, it stops responding. Stomppy 3.1.3 has two ways of handling
this, but stomppy 3.0.3 (EPEL 5 and 6) has neither.
To get around this, we begin and then abort a STOMP transaction to
keep the connection active.
'''
# Use time as transaction id to ensure uniqueness within each connection
transaction_id = str(time.time())
self._conn.begin({'transaction': transaction_id})
self._conn.abort({'transaction': transaction_id})
def has_msgs(self):
'''
Return True if there are any messages in the outgoing queue.
'''
return self._outq.count() > 0
def send_all(self):
'''
Send all the messages in the outgoing queue.
'''
log.info('Found %s messages.', self._outq.count())
for msgid in self._outq:
if not self._outq.lock(msgid):
log.warn('Message was locked. %s will not be sent.', msgid)
continue
text = self._outq.get(msgid)
self._send_msg(text, msgid)
log.info('Waiting for broker to accept message.')
while self._last_msg is None:
if not self.connected:
raise Ssm2Exception('Lost connection.')
time.sleep(0.1)
self._last_msg = None
self._outq.remove(msgid)
log.info('Tidying message directory.')
try:
# Remove empty dirs and unlock msgs older than 5 min (default)
self._outq.purge()
except OSError, e:
log.warn('OSError raised while purging message queue: %s', e)
############################################################################
# Connection handling methods
############################################################################
def _initialise_connection(self, host, port):
'''
Create the self._connection object with the appropriate properties,
but don't try to start the connection.
'''
if self._use_ssl:
if ssl is None:
raise ImportError("SSL connection requested but the ssl module "
"wasn't found.")
log.info('Connecting using SSL...')
try:
# Compatible with stomp.py >= 3.0.4
self._conn = stomp.Connection([(host, port)],
use_ssl=self._use_ssl,
user=self._user,
passcode=self._pwd,
ssl_key_file=self._key,
ssl_cert_file=self._cert,
ssl_version=ssl.PROTOCOL_SSLv23)
except TypeError:
# For stomp.py <= 3.0.3, override ssl.PROTOCOL_SSLv3 and then
# try to set up the connection again below.
ssl.PROTOCOL_SSLv3 = ssl.PROTOCOL_SSLv23
if self._conn is None:
# If _conn is None then either SSL wasn't requested or trying to
# set ssl_version failed.
self._conn = stomp.Connection([(host, port)],
use_ssl=self._use_ssl,
user=self._user,
passcode=self._pwd,
ssl_key_file=self._key,
ssl_cert_file=self._cert)
# You can set this in the constructor but only for stomppy version 3.
# This works for stomppy 3 but doesn't break stomppy 2.
self._conn.__reconnect_attempts_max = 1
self._conn.__timeout = Ssm2.CONNECTION_TIMEOUT
self._conn.set_listener('SSM', self)
def handle_connect(self):
'''
Assuming that the SSM has retrieved the details of the broker or
brokers it wants to connect to, connect to one.
If more than one is in the list self._network_brokers, try to
connect to each in turn until successful.
'''
for host, port in self._brokers:
self._initialise_connection(host, port)
try:
self.start_connection()
break
except ConnectFailedException, e:
# ConnectFailedException doesn't provide a message.
log.warn('Failed to connect to %s:%s.', host, port)
except Ssm2Exception, e:
log.warn('Failed to connect to %s:%s: %s', host, port, e)
if not self.connected:
raise Ssm2Exception('Attempts to start the SSM failed. The system will exit.')
def handle_disconnect(self):
'''
When disconnected, attempt to reconnect using the same method as used
when starting up.
'''
self.connected = False
# Shut down properly
self.close_connection()
# Sometimes the SSM will reconnect to the broker before it's properly
# shut down! This prevents that.
time.sleep(2)
# Try again according to the same logic as the initial startup
try:
self.handle_connect()
except Ssm2Exception:
self.connected = False
# If reconnection fails, admit defeat.
if not self.connected:
err_msg = 'Reconnection attempts failed and have been abandoned.'
raise Ssm2Exception(err_msg)
def start_connection(self):
'''
Once self._connection exists, attempt to start it and subscribe
to the relevant topics.
If the timeout is reached without receiving confirmation of
connection, raise an exception.
'''
if self._conn is None:
raise Ssm2Exception('Called start_connection() before a \
connection object was initialised.')
self._conn.start()
self._conn.connect(wait = True)
if self._dest is not None:
log.info('Will send messages to: %s', self._dest)
if self._listen is not None:
self._conn.subscribe(destination=self._listen, ack='auto')
log.info('Subscribing to: %s', self._listen)
i = 0
while not self.connected:
time.sleep(0.1)
if i > Ssm2.CONNECTION_TIMEOUT * 10:
err = 'Timed out while waiting for connection. '
err += 'Check the connection details.'
raise Ssm2Exception(err)
i += 1
def close_connection(self):
'''
Close the connection. This is important because it runs
in a separate thread, so it can outlive the main process
if it is not ended.
'''
try:
self._conn.stop() # Same as diconnect() but waits for thread exit
except (stomp.exception.NotConnectedException, socket.error):
self._conn = None
except AttributeError:
# AttributeError if self._connection is None already
pass
log.info('SSM connection ended.')
def startup(self):
'''
Create the pidfile then start the connection.
'''
if self._pidfile is not None:
try:
f = open(self._pidfile, 'w')
f.write(str(os.getpid()))
f.write('\n')
f.close()
except IOError, e:
log.warn('Failed to create pidfile %s: %s', self._pidfile, e)
self.handle_connect()
def shutdown(self):
'''
Close the connection then remove the pidfile.
'''
self.close_connection()
if self._pidfile is not None:
try:
if os.path.exists(self._pidfile):
os.remove(self._pidfile)
else:
log.warn('pidfile %s not found.', self._pidfile)
except IOError, e:
log.warn('Failed to remove pidfile %s: %e', self._pidfile, e)
log.warn('SSM may not start again until it is removed.')
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