ncclient:NETCONF Python client

# Copyright 2009 Shikhar Bhushan

#

# 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.

from threading import Thread, Lock, Event

from Queue import Queue

from . import logger

from ncclient.capabilities import Capabilities, CAPABILITIES

class Subject:

    def __init__(self):

        self._listeners = set([])

        self._lock = Lock()

    def has_listener(self, listener):

        with self._lock:

            return (listener in self._listeners)

    def add_listener(self, listener):

        with self._lock:

            self._listeners.add(listener)

    def remove_listener(self, listener):

        with self._lock:

            self._listeners.discard(listener)

    def dispatch(self, event, *args, **kwds):

        # holding the lock while doing callbacks could lead to a deadlock

        # if one of the above methods is called

        with self._lock:

            listeners = list(self._listeners)

        for l in listeners:

            try:

                logger.debug('dispatching [%s] to [%s]' % (event, l))

                getattr(l, event)(*args, **kwds)

            except Exception as e:

                pass # if a listener doesn't care for some event we don't care

class Session(Thread, Subject):

    def __init__(self):

        Thread.__init__(self, name='session')

        Subject.__init__(self)

        self._client_capabilities = CAPABILITIES

        self._server_capabilities = None # yet

        self._id = None # session-id

        self._q = Queue()

        self._connected = False # to be set/cleared by subclass implementation

    def _post_connect(self):

        from ncclient.content.builders import HelloBuilder

        self.send(HelloBuilder.build(self._client_capabilities))

        error = None

        init_event = Event()

        # callbacks

        def ok_cb(id, capabilities):

            self._id, self._server_capabilities = id, Capabilities(capabilities)

            init_event.set()

        def err_cb(err):

            error = err

            init_event.set()

        listener = HelloListener(ok_cb, err_cb)

        self.add_listener(listener)

        # start the subclass' main loop

        self.start()

        # we expect server's hello message

        init_event.wait()

        # received hello message or an error happened

        self.remove_listener(listener)

        if error:

            raise error

        logger.info('initialized: session-id=%s | server_capabilities=%s' %

                     (self.id, self.server_capabilities))

    def send(self, message):

        logger.debug('queueing:%s' % message)

        self._q.put(message)

    def connect(self):

        raise NotImplementedError

    def run(self):

        raise NotImplementedError

    ### Properties

    @property

    def client_capabilities(self):

        return self._client_capabilities

    @property

    def server_capabilities(self):

        return self._server_capabilities

    @property

    def connected(self):

        return self._connected

    @property

    def id(self):

        return self._id

class HelloListener:

    def __init__(self, init_cb, error_cb):

        self._init_cb, self._error_cb = init_cb, error_cb

    def __str__(self):

        return 'HelloListener'

    ### Events

    def received(self, raw):

        logger.debug(raw)

        from ncclient.content.parsers import HelloParser

        try:

            id, capabilities = HelloParser.parse(raw)

        except Exception as e:

            self._error_cb(e)

        else:

            self._init_cb(id, capabilities)

    def error(self, err):

        self._error_cb(err)