1 files changed, 47 insertions, 28 deletions
diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index 6a26cb1879..6873a4575d 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -47,37 +47,23 @@ class BaseHandler(object):
         self.event_builder_factory = hs.get_event_builder_factory()
 
     @defer.inlineCallbacks
-    def _filter_events_for_client(self, user_id, events):
-        event_id_to_state = yield self.store.get_state_for_events(
-            frozenset(e.event_id for e in events),
-            types=(
-                (EventTypes.RoomHistoryVisibility, ""),
-                (EventTypes.Member, user_id),
-            )
-        )
+    def _filter_events_for_client(self, user_id, events, is_guest=False):
+        # Assumes that user has at some point joined the room if not is_guest.
 
-        def allowed(event, state):
-            if event.type == EventTypes.RoomHistoryVisibility:
+        def allowed(event, membership, visibility):
+            if visibility == "world_readable":
                 return True
 
-            membership_ev = state.get((EventTypes.Member, user_id), None)
-            if membership_ev:
-                membership = membership_ev.membership
-            else:
-                membership = Membership.LEAVE
+            if is_guest:
+                return False
 
             if membership == Membership.JOIN:
                 return True
 
-            history = state.get((EventTypes.RoomHistoryVisibility, ''), None)
-            if history:
-                visibility = history.content.get("history_visibility", "shared")
-            else:
-                visibility = "shared"
+            if event.type == EventTypes.RoomHistoryVisibility:
+                return not is_guest
 
-            if visibility == "public":
-                return True
-            elif visibility == "shared":
+            if visibility == "shared":
                 return True
             elif visibility == "joined":
                 return membership == Membership.JOIN
@@ -86,11 +72,44 @@ class BaseHandler(object):
 
             return True
 
-        defer.returnValue([
-            event
-            for event in events
-            if allowed(event, event_id_to_state[event.event_id])
-        ])
+        event_id_to_state = yield self.store.get_state_for_events(
+            frozenset(e.event_id for e in events),
+            types=(
+                (EventTypes.RoomHistoryVisibility, ""),
+                (EventTypes.Member, user_id),
+            )
+        )
+
+        events_to_return = []
+        for event in events:
+            state = event_id_to_state[event.event_id]
+
+            membership_event = state.get((EventTypes.Member, user_id), None)
+            if membership_event:
+                membership = membership_event.membership
+            else:
+                membership = None
+
+            visibility_event = state.get((EventTypes.RoomHistoryVisibility, ""), None)
+            if visibility_event:
+                visibility = visibility_event.content.get("history_visibility", "shared")
+            else:
+                visibility = "shared"
+
+            should_include = allowed(event, membership, visibility)
+            if should_include:
+                events_to_return.append(event)
+
+        if is_guest and len(events_to_return) < len(events):
+            # This indicates that some events in the requested range were not
+            # visible to guest users. To be safe, we reject the entire request,
+            # so that we don't have to worry about interpreting visibility
+            # boundaries.
+            raise AuthError(403, "User %s does not have permission" % (
+                user_id
+            ))
+
+        defer.returnValue(events_to_return)
 
     def ratelimit(self, user_id):
         time_now = self.clock.time()