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# Copyright 2012 Canonical Ltd. This software is licensed under the
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# GNU Affero General Public License version 3 (see the file LICENSE).
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"""Supporting infrastructure for Piston-based APIs in MAAS."""
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from __future__ import (
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'AnonymousOperationsHandler',
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from django.core.exceptions import PermissionDenied
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from django.http import HttpResponseBadRequest
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from piston.handler import (
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from piston.resource import Resource
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class OperationsResource(Resource):
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"""A resource supporting operation dispatch.
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All requests are passed onto the handler's `dispatch` method. See
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:class:`OperationsHandler`.
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crudmap = Resource.callmap
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callmap = dict.fromkeys(crudmap, "dispatch")
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class RestrictedResource(OperationsResource):
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"""A resource that's restricted to active users."""
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def authenticate(self, request, rm):
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actor, anonymous = super(
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RestrictedResource, self).authenticate(request, rm)
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if not anonymous and not request.user.is_active:
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raise PermissionDenied("User is not allowed access to this API.")
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return actor, anonymous
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class AdminRestrictedResource(RestrictedResource):
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"""A resource that's restricted to administrators."""
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def authenticate(self, request, rm):
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actor, anonymous = super(
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AdminRestrictedResource, self).authenticate(request, rm)
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if anonymous or not request.user.is_superuser:
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raise PermissionDenied("User is not allowed access to this API.")
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return actor, anonymous
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def operation(idempotent, exported_as=None):
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"""Decorator to make a method available on the API.
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:param idempotent: If this operation is idempotent. Idempotent operations
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are made available via HTTP GET, non-idempotent operations via HTTP
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:param exported_as: Optional operation name; defaults to the name of the
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method = "GET" if idempotent else "POST"
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if exported_as is None:
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func.export = method, func.__name__
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func.export = method, exported_as
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class OperationsHandlerType(HandlerMetaClass):
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"""Type for handlers that dispatch operations.
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Collects all the exported operations, CRUD and custom, into the class's
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`exports` attribute. This is a signature:function mapping, where signature
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is an (http-method, operation-name) tuple. If operation-name is None, it's
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The `allowed_methods` attribute is calculated as the union of all HTTP
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methods required for the exported CRUD and custom operations.
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def __new__(metaclass, name, bases, namespace):
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cls = super(OperationsHandlerType, metaclass).__new__(
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metaclass, name, bases, namespace)
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# Create a signature:function mapping for CRUD operations.
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(http_method, None): getattr(cls, method)
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for http_method, method in OperationsResource.crudmap.items()
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if getattr(cls, method, None) is not None
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# Create a signature:function mapping for non-CRUD operations.
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attribute.export: attribute
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for attribute in vars(cls).values()
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if getattr(attribute, "export", None) is not None
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# Create the exports mapping.
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exports.update(operations)
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cls.exports = exports
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cls.allowed_methods = frozenset(
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http_method for http_method, name in exports)
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class OperationsHandlerMixin:
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"""Handler mixin for operations dispatch.
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This enabled dispatch to custom functions that piggyback on HTTP methods
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that ordinarily, in Piston, are used for CRUD operations.
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This must be used in cooperation with :class:`OperationsResource` and
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:class:`OperationsHandlerType`.
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def dispatch(self, request, *args, **kwargs):
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signature = request.method.upper(), request.REQUEST.get("op")
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function = self.exports.get(signature)
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return HttpResponseBadRequest(
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"Unrecognised signature: %s %s" % signature)
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return function(self, request, *args, **kwargs)
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class OperationsHandler(
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OperationsHandlerMixin, BaseHandler):
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"""Base handler that supports operation dispatch."""
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__metaclass__ = OperationsHandlerType
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class AnonymousOperationsHandler(
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OperationsHandlerMixin, AnonymousBaseHandler):
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"""Anonymous base handler that supports operation dispatch."""
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__metaclass__ = OperationsHandlerType
added
removed
src/maasserver/api_support.py
