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.

import logging

from threading import Thread, Lock, Event

from Queue import Queue

from capabilities import Capabilities, CAPABILITIES

logger = logging.getLogger('ncclient.session')

class SessionError(Exception):

    pass

class SessionCloseError(SessionError):

    def __init__(self, in_buf, out_buf=None):

        SessionError.__init__(self)

        self._in_buf, self._out_buf = in_buf, out_buf

    def __str__(self):

        msg = 'Session closed by remote endpoint.'

        if self._in_buf:

            msg += '\nIN_BUFFER: %s' % self._in_buf

        if self._out_buf:

            msg += '\nOUT_BUFFER: %s' % self._out_buf

        return msg

class Session(Thread):

    def __init__(self):

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

        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

        self._listeners = set([])

        self._lock = Lock()

    def _post_connect(self):

        from ncclient.content.builders import HelloBuilder

        # queue client's hello message for sending

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

        error = None

        proceed = Event()

        def ok_cb(id, capabilities):

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

            proceed.set()

        def err_cb(err):

            error = err

            proceed.set()

        listener = HelloListener(ok_cb, err_cb)

        self.add_listener(listener)

        # start the subclass' main loop

        self.start()        

        # we expect server's hello message

        proceed.wait()

        # received hello message or an error happened

        self.remove_listener(listener)

        if error:

            self._close()

            raise self._error

    def send(self, message):

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

        self._q.put(message)

    def connect(self):

        raise NotImplementedError

    def run(self):

        raise NotImplementedError

    def capabilities(self, whose='client'):

        if whose == 'client':

            return self._client_capabilities

        elif whose == 'server':

            return self._server_capabilities

    ### Session is a subject for arbitary listeners

    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:

                logger.warning(e)

    ### 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 reply(self, 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)

class DebugListener:

    def __str__(self):

        return 'DebugListener'

    def reply(self, raw):

        logger.debug('DebugListener:reply:%s' % raw)

    def error(self, err):

        logger.debug('DebugListener:error:%s' % err)