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# vim: tabstop=4 shiftwidth=4 softtabstop=4# Copyright 2012 Nebula, Inc.## 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."""Exceptions raised by the Horizon code and the machinery for handling them."""import loggingimport sysfrom django.conf import settingsfrom django.contrib import messagesfrom django.utils.translation import ugettext as _from cloudfiles import errors as swiftclientfrom glanceclient.common import exceptions as glanceclientfrom keystoneclient import exceptions as keystoneclientfrom novaclient import exceptions as novaclientLOG = logging.getLogger(__name__)class HorizonException(Exception): """ Base exception class for distinguishing our own exception classes. """ passclass Http302(HorizonException): """ Error class which can be raised from within a handler to cause an early bailout and redirect at the middleware level. """ status_code = 302 def __init__(self, location, message=None): self.location = location self.message = messageclass NotAuthorized(HorizonException): """ Raised whenever a user attempts to access a resource which they do not have role-based access to (such as when failing the :func:`~horizon.decorators.require_roles` decorator). The included :class:`~horizon.middleware.HorizonMiddleware` catches ``NotAuthorized`` and handles it gracefully by displaying an error message and redirecting the user to a login page. """ status_code = 401class NotAuthenticated(HorizonException): """ Raised when a user is trying to make requests and they are not logged in. The included :class:`~horizon.middleware.HorizonMiddleware` catches ``NotAuthenticated`` and handles it gracefully by displaying an error message and redirecting the user to a login page. """ status_code = 403class NotFound(HorizonException): """ Generic error to replace all "Not Found"-type API errors. """ status_code = 404class RecoverableError(HorizonException): """ Generic error to replace any "Recoverable"-type API errors. """ status_code = 100 # HTTP status code "Continue"class ServiceCatalogException(HorizonException): """ Raised when a requested service is not available in the ``ServiceCatalog`` returned by Keystone. """ def __init__(self, service_name): message = 'Invalid service catalog service: %s' % service_name super(ServiceCatalogException, self).__init__(message)class AlreadyExists(HorizonException): """ Exception to be raised when trying to create an API resource which already exists. """ def __init__(self, name, resource_type): self.attrs = {"name": name, "resource": resource_type} self.msg = 'A %(resource)s with the name "%(name)s" already exists.' def __repr__(self): return self.msg % self.attrs def __unicode__(self): return _(self.msg) % self.attrsclass HandledException(HorizonException): """ Used internally to track exceptions that have gone through :func:`horizon.exceptions.handle` more than once. """ def __init__(self, wrapped): self.wrapped = wrappedHORIZON_CONFIG = getattr(settings, "HORIZON_CONFIG", {})EXCEPTION_CONFIG = HORIZON_CONFIG.get("exceptions", {})UNAUTHORIZED = (keystoneclient.Unauthorized, keystoneclient.Forbidden, novaclient.Unauthorized, novaclient.Forbidden, glanceclient.AuthorizationFailure, glanceclient.Unauthorized, swiftclient.AuthenticationFailed, swiftclient.AuthenticationError)UNAUTHORIZED += tuple(EXCEPTION_CONFIG.get('unauthorized', []))NOT_FOUND = (keystoneclient.NotFound, novaclient.NotFound, glanceclient.NotFound, swiftclient.NoSuchContainer, swiftclient.NoSuchObject)NOT_FOUND += tuple(EXCEPTION_CONFIG.get('not_found', []))# NOTE(gabriel): This is very broad, and may need to be dialed in.RECOVERABLE = (keystoneclient.ClientException, # AuthorizationFailure is raised when Keystone is "unavailable". keystoneclient.AuthorizationFailure, novaclient.ClientException, glanceclient.ClientException, swiftclient.Error, AlreadyExists)RECOVERABLE += tuple(EXCEPTION_CONFIG.get('recoverable', []))def handle(request, message=None, redirect=None, ignore=False, escalate=False): """ Centralized error handling for Horizon. Because Horizon consumes so many different APIs with completely different ``Exception`` types, it's necessary to have a centralized place for handling exceptions which may be raised. Exceptions are roughly divided into 3 types: #. ``UNAUTHORIZED``: Errors resulting from authentication or authorization problems. These result in being logged out and sent to the login screen. #. ``NOT_FOUND``: Errors resulting from objects which could not be located via the API. These generally result in a user-facing error message, but are otherwise returned to the normal code flow. Optionally a redirect value may be passed to the error handler so users are returned to a different view than the one requested in addition to the error message. #. RECOVERABLE: Generic API errors which generate a user-facing message but drop directly back to the regular code flow. All other exceptions bubble the stack as normal unless the ``ignore`` argument is passed in as ``True``, in which case only unrecognized errors are bubbled. If the exception is not re-raised, an appropriate wrapper exception class indicating the type of exception that was encountered will be returned. """ exc_type, exc_value, exc_traceback = sys.exc_info() # Because the same exception may travel through this method more than # once (if it's re-raised) we may want to treat it differently # the second time (e.g. no user messages/logging). handled = issubclass(exc_type, HandledException) wrap = False # Restore our original exception information, but re-wrap it at the end if handled: exc_type, exc_value, exc_traceback = exc_value.wrapped wrap = True # We trust messages from our own exceptions if issubclass(exc_type, HorizonException): message = exc_value # If the message has a placeholder for the exception, fill it in elif message and "%(exc)s" in message: message = message % {"exc": exc_value} if issubclass(exc_type, UNAUTHORIZED): if ignore: return NotAuthorized # BUG: NVD-CWE-Other Other # request.session.clear() # FIXED: request.user_logout() if not handled: LOG.debug("Unauthorized: %s" % exc_value) # We get some pretty useless error messages back from # some clients, so let's define our own fallback. fallback = _("Unauthorized. Please try logging in again.") messages.error(request, message or fallback, extra_tags="login") raise NotAuthorized # Redirect handled in middleware if issubclass(exc_type, NOT_FOUND): wrap = True if not ignore and not handled: LOG.debug("Not Found: %s" % exc_value) messages.error(request, message or exc_value) if redirect: raise Http302(redirect) if not escalate: return NotFound # return to normal code flow if issubclass(exc_type, RECOVERABLE): wrap = True if not ignore and not handled: LOG.debug("Recoverable error: %s" % exc_value) messages.error(request, message or exc_value) if redirect: raise Http302(redirect) if not escalate: return RecoverableError # return to normal code flow # If we've gotten here, time to wrap and/or raise our exception. if wrap: raise HandledException([exc_type, exc_value, exc_traceback]) raise exc_type, exc_value, exc_traceback |