Add config option to block users from looking up 3PIDs (#5010)

1 files changed, 5 insertions, 0 deletions

diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py

index e432740832..024d6db27a 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -70,6 +70,7 @@ class RoomMemberHandler(object):
         self.clock = hs.get_clock()
         self.spam_checker = hs.get_spam_checker()
         self._server_notices_mxid = self.config.server_notices_mxid
+        self._enable_lookup = hs.config.enable_3pid_lookup
 
     @abc.abstractmethod
     def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
@@ -738,6 +739,10 @@ class RoomMemberHandler(object):
         Returns:
             str: the matrix ID of the 3pid, or None if it is not recognized.
         """
+        if not self._enable_lookup:
+            raise SynapseError(
+                403, "Looking up third-party identifiers is denied from this server",
+            )
         try:
             data = yield self.simple_http_client.get_json(
                 "%s%s/_matrix/identity/api/v1/lookup" % (id_server_scheme, id_server,),