From 659898ffaf24f74b62e73c487cd81bad21904790 Mon Sep 17 00:00:00 2001
From: Tom Christie <tomchristie@bright-interactive.co.uk>
Date: Wed, 27 Apr 2011 18:08:32 +0100
Subject: [PATCH] Inital pass at generic permissions, throttling etc.

---
 djangorestframework/permissions.py      | 74 +++++++++++++++++++++++++
 djangorestframework/tests/throttling.py | 38 +++++++++++++
 2 files changed, 112 insertions(+)
 create mode 100644 djangorestframework/permissions.py
 create mode 100644 djangorestframework/tests/throttling.py

diff --git a/djangorestframework/permissions.py b/djangorestframework/permissions.py
new file mode 100644
index 000000000..98d4b0be3
--- /dev/null
+++ b/djangorestframework/permissions.py
@@ -0,0 +1,74 @@
+from django.core.cache import cache
+from djangorestframework import status
+import time
+
+
+class BasePermission(object):
+    """A base class from which all permission classes should inherit."""
+    def __init__(self, view):
+        self.view = view
+    
+    def has_permission(self, auth):
+        return True
+
+class IsAuthenticated(BasePermission):
+    """"""
+    def has_permission(self, auth):
+        return auth is not None and auth.is_authenticated()
+
+#class IsUser(BasePermission):
+#    """The request has authenticated as a user."""
+#    def has_permission(self, auth):
+#        pass
+#
+#class IsAdminUser():
+#    """The request has authenticated as an admin user."""
+#    def has_permission(self, auth):
+#        pass
+#
+#class IsUserOrIsAnonReadOnly(BasePermission):
+#    """The request has authenticated as a user, or is a read-only request."""
+#    def has_permission(self, auth):
+#        pass
+#
+#class OAuthTokenInScope(BasePermission):
+#    def has_permission(self, auth):
+#        pass
+#
+#class UserHasModelPermissions(BasePermission):
+#    def has_permission(self, auth):
+#        pass
+    
+
+class Throttling(BasePermission):
+    """Rate throttling of requests on a per-user basis.
+
+    The rate is set by a 'throttle' attribute on the view class.
+    The attribute is a two tuple of the form (number of requests, duration in seconds).
+
+    The user's id will be used as a unique identifier if the user is authenticated.
+    For anonymous requests, the IP address of the client will be used.
+
+    Previous request information used for throttling is stored in the cache.
+    """
+    def has_permission(self, auth):
+        (num_requests, duration) = getattr(self.view, 'throttle', (0, 0))
+
+        if auth.is_authenticated():
+            ident = str(auth)
+        else:
+            ident = self.view.request.META.get('REMOTE_ADDR', None)
+
+        key = 'throttle_%s' % ident
+        history = cache.get(key, [])
+        now = time.time()
+        
+        # Drop any requests from the history which have now passed the throttle duration
+        while history and history[0] < now - duration:
+            history.pop()
+
+        if len(history) >= num_requests:
+            raise ErrorResponse(status.HTTP_503_SERVICE_UNAVAILABLE, {'detail': 'request was throttled'})
+
+        history.insert(0, now)
+        cache.set(key, history, duration)        
diff --git a/djangorestframework/tests/throttling.py b/djangorestframework/tests/throttling.py
new file mode 100644
index 000000000..46383271f
--- /dev/null
+++ b/djangorestframework/tests/throttling.py
@@ -0,0 +1,38 @@
+from django.conf.urls.defaults import patterns
+from django.test import TestCase
+from django.utils import simplejson as json
+
+from djangorestframework.compat import RequestFactory
+from djangorestframework.resource import Resource
+from djangorestframework.permissions import Throttling
+
+
+class MockResource(Resource):
+    permissions = ( Throttling, )
+    throttle = (3, 1) # 3 requests per second
+
+    def get(self, request):
+        return 'foo'
+
+urlpatterns = patterns('',
+    (r'^$', MockResource.as_view()),
+)
+
+
+#class ThrottlingTests(TestCase):
+#    """Basic authentication"""
+#    urls = 'djangorestframework.tests.throttling'      
+#
+#    def test_requests_are_throttled(self):
+#        """Ensure request rate is limited"""
+#        for dummy in range(3):
+#            response = self.client.get('/')
+#        response = self.client.get('/')
+#        
+#    def test_request_throttling_is_per_user(self):
+#        """Ensure request rate is only limited per user, not globally"""
+#        pass
+#    
+#    def test_request_throttling_expires(self):
+#        """Ensure request rate is limited for a limited duration only"""
+#        pass