Don't ratelimit autojoining of rooms (#8921)

Fixes #8866

4 files changed, 34 insertions, 11 deletions

diff --git a/changelog.d/8921.bugfix b/changelog.d/8921.bugfix
new file mode 100644
index 0000000000..7f6f0b8a76
--- /dev/null
+++ b/changelog.d/8921.bugfix
@@ -0,0 +1 @@
+Fix bug where we ratelimited auto joining of rooms on registration (using `auto_join_rooms` config).
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 930047e730..82fb72b381 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -440,6 +440,7 @@ class RoomCreationHandler(BaseHandler):
             invite_list=[],
             initial_state=initial_state,
             creation_content=creation_content,
+            ratelimit=False,
         )
 
         # Transfer membership events
@@ -735,6 +736,7 @@ class RoomCreationHandler(BaseHandler):
             room_alias=room_alias,
             power_level_content_override=power_level_content_override,
             creator_join_profile=creator_join_profile,
+            ratelimit=ratelimit,
         )
 
         if "name" in config:
@@ -838,6 +840,7 @@ class RoomCreationHandler(BaseHandler):
         room_alias: Optional[RoomAlias] = None,
         power_level_content_override: Optional[JsonDict] = None,
         creator_join_profile: Optional[JsonDict] = None,
+        ratelimit: bool = True,
     ) -> int:
         """Sends the initial events into a new room.
 
@@ -884,7 +887,7 @@ class RoomCreationHandler(BaseHandler):
             creator.user,
             room_id,
             "join",
-            ratelimit=False,
+            ratelimit=ratelimit,
             content=creator_join_profile,
         )
 
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index c002886324..d85110a35e 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -203,7 +203,7 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
 
             # Only rate-limit if the user actually joined the room, otherwise we'll end
             # up blocking profile updates.
-            if newly_joined:
+            if newly_joined and ratelimit:
                 time_now_s = self.clock.time()
                 (
                     allowed,
@@ -488,17 +488,20 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
                     raise AuthError(403, "Guest access not allowed")
 
             if not is_host_in_room:
-                time_now_s = self.clock.time()
-                (
-                    allowed,
-                    time_allowed,
-                ) = self._join_rate_limiter_remote.can_requester_do_action(requester,)
-
-                if not allowed:
-                    raise LimitExceededError(
-                        retry_after_ms=int(1000 * (time_allowed - time_now_s))
+                if ratelimit:
+                    time_now_s = self.clock.time()
+                    (
+                        allowed,
+                        time_allowed,
+                    ) = self._join_rate_limiter_remote.can_requester_do_action(
+                        requester,
                     )
 
+                    if not allowed:
+                        raise LimitExceededError(
+                            retry_after_ms=int(1000 * (time_allowed - time_now_s))
+                        )
+
                 inviter = await self._get_inviter(target.to_string(), room_id)
                 if inviter and not self.hs.is_mine(inviter):
                     remote_room_hosts.append(inviter.domain)
diff --git a/tests/rest/client/v1/test_rooms.py b/tests/rest/client/v1/test_rooms.py
index e67de41c18..55d872f0ee 100644
--- a/tests/rest/client/v1/test_rooms.py
+++ b/tests/rest/client/v1/test_rooms.py
@@ -26,6 +26,7 @@ from mock import Mock
 import synapse.rest.admin
 from synapse.api.constants import EventContentFields, EventTypes, Membership
 from synapse.handlers.pagination import PurgeStatus
+from synapse.rest import admin
 from synapse.rest.client.v1 import directory, login, profile, room
 from synapse.rest.client.v2_alpha import account
 from synapse.types import JsonDict, RoomAlias, UserID
@@ -625,6 +626,7 @@ class RoomJoinRatelimitTestCase(RoomBase):
     user_id = "@sid1:red"
 
     servlets = [
+        admin.register_servlets,
         profile.register_servlets,
         room.register_servlets,
     ]
@@ -703,6 +705,20 @@ class RoomJoinRatelimitTestCase(RoomBase):
                 request, channel = self.make_request("POST", path % room_id, {})
                 self.assertEquals(channel.code, 200)
 
+    @unittest.override_config(
+        {
+            "rc_joins": {"local": {"per_second": 0.5, "burst_count": 3}},
+            "auto_join_rooms": ["#room:red", "#room2:red", "#room3:red", "#room4:red"],
+            "autocreate_auto_join_rooms": True,
+        },
+    )
+    def test_autojoin_rooms(self):
+        user_id = self.register_user("testuser", "password")
+
+        # Check that the new user successfully joined the four rooms
+        rooms = self.get_success(self.hs.get_datastore().get_rooms_for_user(user_id))
+        self.assertEqual(len(rooms), 4)
+
 
 class RoomMessagesTestCase(RoomBase):
     """ Tests /rooms/$room_id/messages/$user_id/$msg_id REST events. """