2 files changed, 28 insertions, 0 deletions
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index d4037b3d55..8bc7b9e6db 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -120,6 +120,22 @@ class AuthError(SynapseError):
         super(AuthError, self).__init__(*args, **kwargs)
 
 
+class GuestAccessError(AuthError):
+    """An error raised when a there is a problem with a guest user accessing
+    a room"""
+
+    def __init__(self, rooms, *args, **kwargs):
+        self.rooms = rooms
+        super(GuestAccessError, self).__init__(*args, **kwargs)
+
+    def error_dict(self):
+        return cs_error(
+            self.msg,
+            self.errcode,
+            rooms=self.rooms,
+        )
+
+
 class EventSizeError(SynapseError):
     """An error raised when an event is too big."""
 
diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index 4390d01e38..5287aaa757 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -149,6 +149,9 @@ class FilterCollection(object):
             "include_leave", False
         )
 
+    def list_rooms(self):
+        return self.room_filter.list_rooms()
+
     def timeline_limit(self):
         return self.room_timeline_filter.limit()
 
@@ -181,6 +184,15 @@ class Filter(object):
     def __init__(self, filter_json):
         self.filter_json = filter_json
 
+    def list_rooms(self):
+        """The list of room_id strings this filter restricts the output to
+        or None if the this filter doesn't list the room ids.
+        """
+        if "rooms" in self.filter_json:
+            return list(set(self.filter_json["rooms"]))
+        else:
+            return None
+
     def check(self, event):
         """Checks whether the filter matches the given event.