neutron/neutron/api/v2/resource.py

# Copyright 2012 OpenStack Foundation.
# All Rights Reserved.
#
#    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.

"""
Utility methods for working with WSGI servers redux
"""

import sys

import netaddr
import oslo_i18n
from oslo_log import log as logging
from oslo_policy import policy as oslo_policy
import six
import webob.dec
import webob.exc

from neutron._i18n import _LE, _LI
from neutron.common import exceptions
from neutron import wsgi


LOG = logging.getLogger(__name__)


class Request(wsgi.Request):
    pass


def Resource(controller, faults=None, deserializers=None, serializers=None):
    """Represents an API entity resource and the associated serialization and
    deserialization logic
    """
    default_deserializers = {'application/json': wsgi.JSONDeserializer()}
    default_serializers = {'application/json': wsgi.JSONDictSerializer()}
    format_types = {'json': 'application/json'}
    action_status = dict(create=201, delete=204)

    default_deserializers.update(deserializers or {})
    default_serializers.update(serializers or {})

    deserializers = default_deserializers
    serializers = default_serializers
    faults = faults or {}

    @webob.dec.wsgify(RequestClass=Request)
    def resource(request):
        route_args = request.environ.get('wsgiorg.routing_args')
        if route_args:
            args = route_args[1].copy()
        else:
            args = {}

        # NOTE(jkoelker) by now the controller is already found, remove
        #                it from the args if it is in the matchdict
        args.pop('controller', None)
        fmt = args.pop('format', None)
        action = args.pop('action', None)
        content_type = format_types.get(fmt,
                                        request.best_match_content_type())
        language = request.best_match_language()
        deserializer = deserializers.get(content_type)
        serializer = serializers.get(content_type)

        try:
            if request.body:
                args['body'] = deserializer.deserialize(request.body)['body']

            method = getattr(controller, action)

            result = method(request=request, **args)
        except (exceptions.NeutronException,
                netaddr.AddrFormatError,
                oslo_policy.PolicyNotAuthorized) as e:
            for fault in faults:
                if isinstance(e, fault):
                    mapped_exc = faults[fault]
                    break
            else:
                mapped_exc = webob.exc.HTTPInternalServerError
            if 400 <= mapped_exc.code < 500:
                LOG.info(_LI('%(action)s failed (client error): %(exc)s'),
                         {'action': action, 'exc': e})
            else:
                LOG.exception(_LE('%s failed'), action)
            e = translate(e, language)
            body = serializer.serialize(
                {'NeutronError': get_exception_data(e)})
            kwargs = {'body': body, 'content_type': content_type}
            raise mapped_exc(**kwargs)
        except webob.exc.HTTPException as e:
            type_, value, tb = sys.exc_info()
            if hasattr(e, 'code') and 400 <= e.code < 500:
                LOG.info(_LI('%(action)s failed (client error): %(exc)s'),
                         {'action': action, 'exc': e})
            else:
                LOG.exception(_LE('%s failed'), action)
            translate(e, language)
            value.body = serializer.serialize(
                {'NeutronError': get_exception_data(e)})
            value.content_type = content_type
            six.reraise(type_, value, tb)
        except NotImplementedError as e:
            e = translate(e, language)
            # NOTE(armando-migliaccio): from a client standpoint
            # it makes sense to receive these errors, because
            # extensions may or may not be implemented by
            # the underlying plugin. So if something goes south,
            # because a plugin does not implement a feature,
            # returning 500 is definitely confusing.
            body = serializer.serialize(
                {'NotImplementedError': get_exception_data(e)})
            kwargs = {'body': body, 'content_type': content_type}
            raise webob.exc.HTTPNotImplemented(**kwargs)
        except Exception:
            # NOTE(jkoelker) Everything else is 500
            LOG.exception(_LE('%s failed'), action)
            # Do not expose details of 500 error to clients.
            msg = _('Request Failed: internal server error while '
                    'processing your request.')
            msg = translate(msg, language)
            body = serializer.serialize(
                {'NeutronError': get_exception_data(
                    webob.exc.HTTPInternalServerError(msg))})
            kwargs = {'body': body, 'content_type': content_type}
            raise webob.exc.HTTPInternalServerError(**kwargs)

        status = action_status.get(action, 200)
        body = serializer.serialize(result)
        # NOTE(jkoelker) Comply with RFC2616 section 9.7
        if status == 204:
            content_type = ''
            body = None

        return webob.Response(request=request, status=status,
                              content_type=content_type,
                              body=body)
    return resource


def get_exception_data(e):
    """Extract the information about an exception.

    Neutron client for the v2 API expects exceptions to have 'type', 'message'
    and 'detail' attributes.This information is extracted and converted into a
    dictionary.

    :param e: the exception to be reraised
    :returns: a structured dict with the exception data
    """
    err_data = {'type': e.__class__.__name__,
                'message': e, 'detail': ''}
    return err_data


def translate(translatable, locale):
    """Translates the object to the given locale.

    If the object is an exception its translatable elements are translated
    in place, if the object is a translatable string it is translated and
    returned. Otherwise, the object is returned as-is.

    :param translatable: the object to be translated
    :param locale: the locale to translate to
    :returns: the translated object, or the object as-is if it
              was not translated
    """
    localize = oslo_i18n.translate
    if isinstance(translatable, exceptions.NeutronException):
        translatable.msg = localize(translatable.msg, locale)
    elif isinstance(translatable, webob.exc.HTTPError):
        translatable.detail = localize(translatable.detail, locale)
    elif isinstance(translatable, Exception):
        translatable.message = localize(translatable, locale)
    else:
        return localize(translatable, locale)
    return translatable