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 xml.etree import cElementTree as ElementTree

from cStringIO import StringIO

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

def qualify(tag, ns=None):

    if ns is None:

        return tag

    else:

        return '{%s}%s' % (ns, tag)

_ = qualify

class RootElementParser:

    '''Parse the root element of an XML document. The tag and namespace of

    recognized elements, and attributes of interest can be customized.

    RootElementParser does not parse any sub-elements.

    '''

    def __init__(self, recognize=[]):

        self._recognize = recognize

    def recognize(self, element):

        '''Specify an element that should be successfully parsed.

        element should be a string that represents a qualified name of the form

        *{namespace}tag*.

        '''

        self._recognize.append((element, attrs))

    def parse(self, raw):

        '''Parse the root element from a string representing an XML document.

        Returns a (tag, attributes) tuple. tag is a string representing

        the qualified name of the recognized element. attributes is a

        {'attr': value} dictionary.

        '''

        fp = StringIO(raw)

        for event, element in ElementTree.iterparse(fp, events=('start',)):

            for e in self._recognize:

                if element.tag == e:

                    return (element.tag, element.attrib)

            break

        return None

###########

class XMLBuilder:

    @staticmethod

    def _element(node):

        element = ElementTree.Element( _(node.get('tag'),

                                         node.get('namespace', None)),

                                      node.get('attributes', {}))

        if node.has_key('children'):

            for child in node['children']:

                element.append(_make_element(child))

        else:

            return element

    @staticmethod

    def _etree(tree_dict):

        return ElementTree.ElementTree(XMLBuilder._element(tree_dict))

    @staticmethod

    def to_xml(tree_dict, encoding='utf-8'):

        fp = StringIO()

        self._etree(tree_dict).write(fp, encoding)

        return fp.get_value()

### Hello exchange

class Hello:

    NS = 'urn:ietf:params:xml:ns:netconf:base:1.0'

    @staticmethod

    def build(capabilities, encoding='utf-8'):

        hello = ElementTree.Element(_('hello', Hello.NS))

        caps = ElementTree.Element('capabilities')

        for uri in capabilities:

            cap = ElementTree.Element('capability')

            cap.text = uri

            caps.append(cap)

        hello.append(caps)

        tree = ElementTree.ElementTree(hello)

        fp = StringIO()

        tree.write(fp, encoding)

        return fp.getvalue()

    @staticmethod

    def parse(raw):

        'Returns tuple of (session-id, ["capability_uri", ...])'

        id, capabilities = 0, []

        root = ElementTree.fromstring(raw)

        if root.tag == _('hello', Hello.NS):

            for child in root.getchildren():

                if child.tag == _('session-id', Hello.NS):

                    id = int(child.text)

                elif child.tag == _('capabilities', Hello.NS):

                    for cap in child.getiterator(_('capability', Hello.NS)):

                        capabilities.append(cap.text)

        return id, capabilities