mediagoblin/plugins/api/tools.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011, 2012 MediaGoblin contributors.  See AUTHORS.
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Affero General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 import logging
  18 import json
  19
  20 from functools import wraps
  21 from urlparse import urljoin
  22 from werkzeug.exceptions import Forbidden
  23 from werkzeug.wrappers import Response
  24 from mediagoblin import mg_globals
  25 from mediagoblin.tools.pluginapi import PluginManager
  26 from mediagoblin.storage.filestorage import BasicFileStorage
  27
  28 _log = logging.getLogger(__name__)
  29
  30
  31 class Auth(object):
  32     '''
  33     An object with two significant methods, 'trigger' and 'run'.
  34
  35     Using a similar object to this, plugins can register specific
  36     authentication logic, for example the GET param 'access_token' for OAuth.
  37
  38     - trigger: Analyze the 'request' argument, return True if you think you
  39       can handle the request, otherwise return False
  40     - run: The authentication logic, set the request.user object to the user
  41       you intend to authenticate and return True, otherwise return False.
  42
  43     If run() returns False, an HTTP 403 Forbidden error will be shown.
  44
  45     You may also display custom errors, just raise them within the run()
  46     method.
  47     '''
  48     def trigger(self, request):
  49         raise NotImplemented()
  50
  51     def __call__(self, request, *args, **kw):
  52         raise NotImplemented()
  53
  54 def get_entry_serializable(entry, urlgen):
  55     '''
  56     Returns a serializable dict() of a MediaEntry instance.
  57
  58     :param entry: A MediaEntry instance
  59     :param urlgen: An urlgen instance, can be found on the request object passed
  60     to views.
  61     '''
  62     return {
  63             'user': entry.get_uploader.username,
  64             'user_id': entry.get_uploader.id,
  65             'user_bio': entry.get_uploader.bio,
  66             'user_bio_html': entry.get_uploader.bio_html,
  67             'user_permalink': urlgen('mediagoblin.user_pages.user_home',
  68                 user=entry.get_uploader.username,
  69                 qualified=True),
  70             'id': entry.id,
  71             'created': entry.created.isoformat(),
  72             'title': entry.title,
  73             'license': entry.license,
  74             'description': entry.description,
  75             'description_html': entry.description_html,
  76             'media_type': entry.media_type,
  77             'state': entry.state,
  78             'permalink': entry.url_for_self(urlgen, qualified=True),
  79             'media_files': get_media_file_paths(entry.media_files, urlgen)}
  80
  81
  82 def get_media_file_paths(media_files, urlgen):
  83     '''
  84     Returns a dictionary of media files with `file_handle` => `qualified URL`
  85
  86     :param media_files: dict-like object consisting of `file_handle => `listy
  87     filepath` pairs.
  88     :param urlgen: An urlgen object, usually found on request.urlgen.
  89     '''
  90     media_urls = {}
  91
  92     for key, val in media_files.items():
  93         if isinstance(mg_globals.public_store, BasicFileStorage):
  94             # BasicFileStorage does not provide a qualified URI
  95             media_urls[key] = urljoin(
  96                     urlgen('index', qualified=True),
  97                     mg_globals.public_store.file_url(val))
  98         else:
  99             media_urls[key] = mg_globals.public_store.file_url(val)
 100
 101     return media_urls
 102
 103
 104 def api_auth(controller):
 105     '''
 106     Decorator, allows plugins to register auth methods that will then be
 107     evaluated against the request, finally a worthy authenticator object is
 108     chosen and used to decide whether to grant or deny access.
 109     '''
 110     @wraps(controller)
 111     def wrapper(request, *args, **kw):
 112         auth_candidates = []
 113
 114         for auth in PluginManager().get_hook_callables('auth'):
 115             if auth.trigger(request):
 116                 _log.debug('{0} believes it is capable of authenticating this request.'.format(auth))
 117                 auth_candidates.append(auth)
 118
 119         # If we can't find any authentication methods, we should not let them
 120         # pass.
 121         if not auth_candidates:
 122             raise Forbidden()
 123
 124         # For now, just select the first one in the list
 125         auth = auth_candidates[0]
 126
 127         _log.debug('Using {0} to authorize request {1}'.format(
 128             auth, request.url))
 129
 130         if not auth(request, *args, **kw):
 131             if getattr(auth, 'errors', []):
 132                 return json_response({
 133                         'status': 403,
 134                         'errors': auth.errors})
 135
 136             raise Forbidden()
 137
 138         return controller(request, *args, **kw)
 139
 140     return wrapper