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 Event, Lock

from uuid import uuid1

from weakref import WeakValueDictionary

from ncclient import content

from errors import OperationError

import logging

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

class RPCReply:

    'NOTES: memory considerations?? storing both raw xml + ET.Element'

    def __init__(self, raw):

        self._raw = raw

        self._parsed = False

        self._root = None

        self._errors = []

    def __repr__(self):

        return self._raw

    def parse(self):

        if self._parsed:

            return

        root = self._root = content.xml2ele(self._raw) # <rpc-reply> element

        # per rfc 4741 an <ok/> tag is sent when there are no errors or warnings

        ok = content.find(root, 'ok')

        if ok is not None:

            logger.debug('parsed [%s]' % ok.tag)

        else: # create RPCError objects from <rpc-error> elements

            error = content.find(root, 'rpc-error')

            if error is not None:

                logger.debug('parsed [%s]' % error.tag)

                for err in root.getiterator(error.tag):

                    # process a particular <rpc-error>

                    d = {}

                    for err_detail in err.getchildren(): # <error-type> etc..

                        tag = content.unqualify(err_detail.tag)

                        if tag != 'error-info':

                            d[tag] = err_detail.text.strip()

                        else:

                            d[tag] = content.ele2xml(err_detail)

                    self._errors.append(RPCError(d))

        self._parsing_hook(root)

        self._parsed = True

    @property

    def xml(self):

        '<rpc-reply> as returned'

        return self._raw

    @property

    def ok(self):

        if not self._parsed:

            self.parse()

        return not self._errors # empty list => false

    @property

    def error(self):

        if not self._parsed:

            self.parse()

        if self._errors:

            return self._errors[0]

        else:

            return None

    @property

    def errors(self):

        'List of RPCError objects. Will be empty if no <rpc-error> elements in reply.'

        if not self._parsed:

            self.parse()

        return self._errors

class RPCError(OperationError): # raise it if you like

    def __init__(self, err_dict):

        self._dict = err_dict

        if self.message is not None:

            OperationError.__init__(self, self.message)

        else:

            OperationError.__init__(self)

    @property

    def type(self):

        return self.get('error-type', None)

    @property

    def severity(self):

        return self.get('error-severity', None)

    @property

    def tag(self):

        return self.get('error-tag', None)

    @property

    def path(self):

        return self.get('error-path', None)

    @property

    def message(self):

        return self.get('error-message', None)

    @property

    def info(self):

        return self.get('error-info', None)

    ## dictionary interface

    __getitem__ = lambda self, key: self._dict.__getitem__(key)

    __iter__ = lambda self: self._dict.__iter__()

    __contains__ = lambda self, key: self._dict.__contains__(key)

    keys = lambda self: self._dict.keys()

    get = lambda self, key, default: self._dict.get(key, default)

    iteritems = lambda self: self._dict.iteritems()

    iterkeys = lambda self: self._dict.iterkeys()

    itervalues = lambda self: self._dict.itervalues()

    values = lambda self: self._dict.values()

    items = lambda self: self._dict.items()

    __repr__ = lambda self: repr(self._dict)

class RPCReplyListener(object):

    # one instance per session

    def __new__(cls, session):

        instance = session.get_listener_instance(cls)

        if instance is None:

            instance = object.__new__(cls)

            instance._lock = Lock()

            instance._id2rpc = WeakValueDictionary()

            instance._pipelined = session.can_pipeline

            instance._errback = None

            session.add_listener(instance)

        return instance

    def register(self, id, rpc):

        with self._lock:

            self._id2rpc[id] = rpc

    def set_errback(self, errback):

        self._errback = errback

    def callback(self, root, raw):

        tag, attrs = root

        if content.unqualify(tag) != 'rpc-reply':

            return

        rpc = None

        for key in attrs:

            if content.unqualify(key) == 'message-id':

                id = attrs[key]

                try:

                    with self._lock:

                        rpc = self._id2rpc.pop(id)

                except KeyError:

                    logger.warning('no object registered for message-id: [%s]' % id)

                except Exception as e:

                    logger.debug('error - %r' % e)

                break

        else:

            if not self._pipelined:

                with self._lock:

                    assert(len(self._id2rpc) == 1)

                    rpc = self._id2rpc.values()[0]

                    self._id2rpc.clear()

            else:

                logger.warning('<rpc-reply> without message-id received: %s' % raw)

        logger.debug('delivering to %r' % rpc)

        rpc.deliver(raw)

    def errback(self, err):

        if self._errback is not None:

            self._errback(err)

class RPC(object):

    DEPENDS = []

    REPLY_CLS = RPCReply

    def __init__(self, session, async=False, timeout=None):

        if not session.can_pipeline:

            raise UserWarning('Asynchronous mode not supported for this device/session')

        self._session = session

        try:

            for cap in self.DEPENDS:

                self._assert(cap)

        except AttributeError:

            pass        

        self._async = async

        self._timeout = timeout

        # keeps things simple instead of having a class attr that has to be locked

        self._id = uuid1().urn

        # RPCReplyListener itself makes sure there isn't more than one instance -- i.e. multiton

        self._listener = RPCReplyListener(session)

        self._listener.register(self._id, self)

        self._reply = None

        self._reply_event = Event()

    def _build(self, opspec, encoding='utf-8'):

        "TODO: docstring"

        spec = {

            'tag': content.qualify('rpc'),

            'attributes': {'message-id': self._id},

            'subtree': opspec

            }

        return content.dtree2xml(encoding)

    def _request(self, op):

        req = self._build(op)

        self._session.send(req)

        if self._async:

            return self._reply_event

        else:

            self._reply_event.wait(self._timeout)

            if self._reply_event.isSet():

                self._reply.parse()

                return self._reply

            else:

                raise ReplyTimeoutError

    def request(self):

        return self._request(self.SPEC)

    def _delivery_hook(self):

        'For subclasses'

        pass

    def _assert(self, capability):

        if capability not in self._session.server_capabilities:

            raise MissingCapabilityError('Server does not support [%s]' % cap)

    def deliver(self, raw):

        self._reply = self.REPLY_CLS(raw)

        self._delivery_hook()

        self._reply_event.set()

    @property

    def has_reply(self):

        return self._reply_event.isSet()

    @property

    def reply(self):

        return self._reply

    @property

    def id(self):

        return self._id

    @property

    def session(self):

        return self._session

    @property

    def reply_event(self):

        return self._reply_event

    def set_async(self, bool): self._async = bool

    async = property(fget=lambda self: self._async, fset=set_async)

    def set_timeout(self, timeout): self._timeout = timeout

    timeout = property(fget=lambda self: self._timeout, fset=set_timeout)