3 files changed, 22 insertions, 1 deletions
diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index 35faa53746..8c8c7b642e 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -144,6 +144,9 @@ 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()
 
@@ -176,6 +179,15 @@ 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.
 
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 7088c20cb4..75ef742328 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -29,6 +29,7 @@ logger = logging.getLogger(__name__)
 
 SyncConfig = collections.namedtuple("SyncConfig", [
     "user",
+    "is_guest",
     "filter",
 ])
 
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index 697df03dda..35a70ffad1 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -85,7 +85,9 @@ class SyncRestServlet(RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request):
-        user, token_id, _ = yield self.auth.get_user_by_req(request)
+        user, token_id, is_guest = yield self.auth.get_user_by_req(
+            request, allow_guest=True
+        )
 
         timeout = parse_integer(request, "timeout", default=0)
         since = parse_string(request, "since")
@@ -118,8 +120,14 @@ class SyncRestServlet(RestServlet):
             except:
                 filter = FilterCollection({})
 
+        if is_guest and filter.list_rooms() is None:
+            raise SynapseError(
+                400, "Guest users must provide a list of rooms in the filter"
+            )
+
         sync_config = SyncConfig(
             user=user,
+            is_guest=is_guest,
             filter=filter,
         )