root / ncclient / rpc / rpc.py @ cc8de468
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# Copyright 2009 Shikhar Bhushan
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from threading import Event, Lock |
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from uuid import uuid1 |
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from weakref import WeakValueDictionary |
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from ncclient.content import TreeBuilder |
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from ncclient.content import qualify as _ |
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from ncclient.content import unqualify as __ |
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from ncclient.glue import Listener |
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from . import logger
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from reply import RPCReply |
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# Cisco does not include message-id attribute in <rpc-reply> in case of an error.
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# This is messed up however we have to deal with it.
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# So essentially, there can be only one operation at a time if we are talking to
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# a Cisco device.
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def cisco_check(session): |
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try:
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return session.is_remote_cisco
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except AttributeError: |
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return False |
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class RPC(object): |
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def __init__(self, session, async=False): |
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if cisco_check(session) and async: |
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raise UserWarning('Asynchronous mode not supported for Cisco devices') |
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self._session = session
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self._async = async
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self._id = uuid1().urn
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self._listener = RPCReplyListener(session)
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self._listener.register(self._id, self) |
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self._reply = None |
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self._reply_event = Event()
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def _build(self, op, encoding='utf-8'): |
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if isinstance(op, dict): |
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return self.build_from_spec(self._id, op, encoding) |
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else:
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return self.build_from_string(self._id, op, encoding) |
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def _request(self, op): |
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req = self._build(op)
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self._session.send(req)
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if self._async: |
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return self._reply_event |
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else:
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self._reply_event.wait()
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self._reply.parse()
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return self._reply |
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def _delivery_hook(self): |
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'For subclasses'
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pass
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def deliver(self, raw): |
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self._reply = RPCReply(raw)
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self._delivery_hook()
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self._reply_event.set()
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@property
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def has_reply(self): |
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return self._reply_event.isSet() |
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@property
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def reply(self): |
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return self._reply |
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@property
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def is_async(self): |
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return self._async |
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@property
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def id(self): |
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return self._id |
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@property
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def session(self): |
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return self._session |
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@property
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def reply_event(self): |
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return self._reply_event |
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@staticmethod
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def build_from_spec(msgid, opspec, encoding='utf-8'): |
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"TODO: docstring"
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spec = { |
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'tag': _('rpc'), |
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'attributes': {'message-id': msgid}, |
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'children': opspec
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} |
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return TreeBuilder(spec).to_string(encoding)
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@staticmethod
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def build_from_string(msgid, opstr, encoding='utf-8'): |
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"TODO: docstring"
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decl = '<?xml version="1.0" encoding="%s"?>' % encoding
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doc = (u'<rpc message-id="%s" xmlns="%s">%s</rpc>' %
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(msgid, BASE_NS, opstr)).encode(encoding) |
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return '%s%s' % (decl, doc) |
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class RPCReplyListener(Listener): |
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# TODO - determine if need locking
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# one instance per session
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def __new__(cls, session): |
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instance = session.get_listener_instance(cls) |
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if instance is None: |
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instance = object.__new__(cls)
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instance._id2rpc = WeakValueDictionary() |
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instance._cisco = cisco_check(session) |
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instance._errback = None
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session.add_listener(instance) |
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return instance
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def __str__(self): |
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return 'RPCReplyListener' |
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def set_errback(self, errback): |
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self._errback = errback
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def register(self, id, rpc): |
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self._id2rpc[id] = rpc |
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def callback(self, root, raw): |
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tag, attrs = root |
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if __(tag) != 'rpc-reply': |
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return
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rpc = None
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for key in attrs: |
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if __(key) == 'message-id': |
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id = attrs[key] |
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try:
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rpc = self._id2rpc.pop(id) |
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except KeyError: |
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logger.warning('[RPCReplyListener.callback] no object '
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+ 'registered for message-id: [%s]' % id) |
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except Exception as e: |
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logger.debug('[RPCReplyListener.callback] error - %r' % e)
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break
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else:
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if self._cisco: |
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assert(len(self._id2rpc) == 1) |
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rpc = self._id2rpc.values()[0] |
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self._id2rpc.clear()
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else:
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logger.warning('<rpc-reply> without message-id received: %s' % raw)
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logger.debug('[RPCReplyListener.callback] delivering to %r' % rpc)
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rpc.deliver(raw) |
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def errback(self, err): |
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if self._errback is not None: |
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self._errback(err)
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