Add delete room admin endpoint (#7613)

The Delete Room admin API allows server admins to remove rooms from server
and block these rooms.
`DELETE /_synapse/admin/v1/rooms/<room_id>`
It is a combination and improvement of "[Shutdown room](https://github.com/matrix-org/synapse/blob/develop/docs/admin_api/shutdown_room.md)" and "[Purge room](https://github.com/matrix-org/synapse/blob/develop/docs/admin_api/purge_room.md)" API.

Fixes: #6425 

It also fixes a bug in [synapse/storage/data_stores/main/room.py](synapse/storage/data_stores/main/room.py) in ` get_room_with_stats`.
It should return `None` if the room is unknown. But it returns an `IndexError`.
https://github.com/matrix-org/synapse/blob/901b1fa561e3cc661d78aa96d59802cf2078cb0d/synapse/storage/data_stores/main/room.py#L99-L105

Related to:
- #5575
- https://github.com/Awesome-Technologies/synapse-admin/issues/17

Signed-off-by: Dirk Klimpel dirk@klimpel.org

2 files changed, 50 insertions, 109 deletions

diff --git a/synapse/rest/admin/__init__.py b/synapse/rest/admin/__init__.py
index 9eda592de9..dc373bc5a3 100644
--- a/synapse/rest/admin/__init__.py
+++ b/synapse/rest/admin/__init__.py
@@ -35,6 +35,7 @@ from synapse.rest.admin.groups import DeleteGroupAdminRestServlet
 from synapse.rest.admin.media import ListMediaInRoom, register_servlets_for_media_repo
 from synapse.rest.admin.purge_room_servlet import PurgeRoomServlet
 from synapse.rest.admin.rooms import (
+    DeleteRoomRestServlet,
     JoinRoomAliasServlet,
     ListRoomRestServlet,
     RoomRestServlet,
@@ -200,6 +201,7 @@ def register_servlets(hs, http_server):
     register_servlets_for_client_rest_resource(hs, http_server)
     ListRoomRestServlet(hs).register(http_server)
     RoomRestServlet(hs).register(http_server)
+    DeleteRoomRestServlet(hs).register(http_server)
     JoinRoomAliasServlet(hs).register(http_server)
     PurgeRoomServlet(hs).register(http_server)
     SendServerNoticeServlet(hs).register(http_server)
diff --git a/synapse/rest/admin/rooms.py b/synapse/rest/admin/rooms.py
index e07c32118d..544be47060 100644
--- a/synapse/rest/admin/rooms.py
+++ b/synapse/rest/admin/rooms.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+from http import HTTPStatus
 from typing import List, Optional
 
-from synapse.api.constants import EventTypes, JoinRules, Membership, RoomCreationPreset
+from synapse.api.constants import EventTypes, JoinRules
 from synapse.api.errors import Codes, NotFoundError, SynapseError
 from synapse.http.servlet import (
     RestServlet,
@@ -32,7 +33,6 @@ from synapse.rest.admin._base import (
 )
 from synapse.storage.data_stores.main.room import RoomSortOrder
 from synapse.types import RoomAlias, RoomID, UserID, create_requester
-from synapse.util.async_helpers import maybe_awaitable
 
 logger = logging.getLogger(__name__)
 
@@ -46,20 +46,10 @@ class ShutdownRoomRestServlet(RestServlet):
 
     PATTERNS = historical_admin_path_patterns("/shutdown_room/(?P<room_id>[^/]+)")
 
-    DEFAULT_MESSAGE = (
-        "Sharing illegal content on this server is not permitted and rooms in"
-        " violation will be blocked."
-    )
-
     def __init__(self, hs):
         self.hs = hs
-        self.store = hs.get_datastore()
-        self.state = hs.get_state_handler()
-        self._room_creation_handler = hs.get_room_creation_handler()
-        self.event_creation_handler = hs.get_event_creation_handler()
-        self.room_member_handler = hs.get_room_member_handler()
         self.auth = hs.get_auth()
-        self._replication = hs.get_replication_data_handler()
+        self.room_shutdown_handler = hs.get_room_shutdown_handler()
 
     async def on_POST(self, request, room_id):
         requester = await self.auth.get_user_by_req(request)
@@ -67,116 +57,65 @@ class ShutdownRoomRestServlet(RestServlet):
 
         content = parse_json_object_from_request(request)
         assert_params_in_dict(content, ["new_room_user_id"])
-        new_room_user_id = content["new_room_user_id"]
-
-        room_creator_requester = create_requester(new_room_user_id)
-
-        message = content.get("message", self.DEFAULT_MESSAGE)
-        room_name = content.get("room_name", "Content Violation Notification")
 
-        info, stream_id = await self._room_creation_handler.create_room(
-            room_creator_requester,
-            config={
-                "preset": RoomCreationPreset.PUBLIC_CHAT,
-                "name": room_name,
-                "power_level_content_override": {"users_default": -10},
-            },
-            ratelimit=False,
+        ret = await self.room_shutdown_handler.shutdown_room(
+            room_id=room_id,
+            new_room_user_id=content["new_room_user_id"],
+            new_room_name=content.get("room_name"),
+            message=content.get("message"),
+            requester_user_id=requester.user.to_string(),
+            block=True,
         )
-        new_room_id = info["room_id"]
 
-        requester_user_id = requester.user.to_string()
+        return (200, ret)
 
-        logger.info(
-            "Shutting down room %r, joining to new room: %r", room_id, new_room_id
-        )
-
-        # This will work even if the room is already blocked, but that is
-        # desirable in case the first attempt at blocking the room failed below.
-        await self.store.block_room(room_id, requester_user_id)
-
-        # We now wait for the create room to come back in via replication so
-        # that we can assume that all the joins/invites have propogated before
-        # we try and auto join below.
-        #
-        # TODO: Currently the events stream is written to from master
-        await self._replication.wait_for_stream_position(
-            self.hs.config.worker.writers.events, "events", stream_id
-        )
 
-        users = await self.state.get_current_users_in_room(room_id)
-        kicked_users = []
-        failed_to_kick_users = []
-        for user_id in users:
-            if not self.hs.is_mine_id(user_id):
-                continue
+class DeleteRoomRestServlet(RestServlet):
+    """Delete a room from server. It is a combination and improvement of
+    shut down and purge room.
+    Shuts down a room by removing all local users from the room.
+    Blocking all future invites and joins to the room is optional.
+    If desired any local aliases will be repointed to a new room
+    created by `new_room_user_id` and kicked users will be auto
+    joined to the new room.
+    It will remove all trace of a room from the database.
+    """
 
-            logger.info("Kicking %r from %r...", user_id, room_id)
+    PATTERNS = admin_patterns("/rooms/(?P<room_id>[^/]+)/delete$")
 
-            try:
-                target_requester = create_requester(user_id)
-                _, stream_id = await self.room_member_handler.update_membership(
-                    requester=target_requester,
-                    target=target_requester.user,
-                    room_id=room_id,
-                    action=Membership.LEAVE,
-                    content={},
-                    ratelimit=False,
-                    require_consent=False,
-                )
-
-                # Wait for leave to come in over replication before trying to forget.
-                await self._replication.wait_for_stream_position(
-                    self.hs.config.worker.writers.events, "events", stream_id
-                )
+    def __init__(self, hs):
+        self.hs = hs
+        self.auth = hs.get_auth()
+        self.room_shutdown_handler = hs.get_room_shutdown_handler()
+        self.pagination_handler = hs.get_pagination_handler()
 
-                await self.room_member_handler.forget(target_requester.user, room_id)
+    async def on_POST(self, request, room_id):
+        requester = await self.auth.get_user_by_req(request)
+        await assert_user_is_admin(self.auth, requester.user)
 
-                await self.room_member_handler.update_membership(
-                    requester=target_requester,
-                    target=target_requester.user,
-                    room_id=new_room_id,
-                    action=Membership.JOIN,
-                    content={},
-                    ratelimit=False,
-                    require_consent=False,
-                )
+        content = parse_json_object_from_request(request)
 
-                kicked_users.append(user_id)
-            except Exception:
-                logger.exception(
-                    "Failed to leave old room and join new room for %r", user_id
-                )
-                failed_to_kick_users.append(user_id)
-
-        await self.event_creation_handler.create_and_send_nonmember_event(
-            room_creator_requester,
-            {
-                "type": "m.room.message",
-                "content": {"body": message, "msgtype": "m.text"},
-                "room_id": new_room_id,
-                "sender": new_room_user_id,
-            },
-            ratelimit=False,
-        )
+        block = content.get("block", False)
+        if not isinstance(block, bool):
+            raise SynapseError(
+                HTTPStatus.BAD_REQUEST,
+                "Param 'block' must be a boolean, if given",
+                Codes.BAD_JSON,
+            )
 
-        aliases_for_room = await maybe_awaitable(
-            self.store.get_aliases_for_room(room_id)
+        ret = await self.room_shutdown_handler.shutdown_room(
+            room_id=room_id,
+            new_room_user_id=content.get("new_room_user_id"),
+            new_room_name=content.get("room_name"),
+            message=content.get("message"),
+            requester_user_id=requester.user.to_string(),
+            block=block,
         )
 
-        await self.store.update_aliases_for_room(
-            room_id, new_room_id, requester_user_id
-        )
+        # Purge room
+        await self.pagination_handler.purge_room(room_id)
 
-        return (
-            200,
-            {
-                "kicked_users": kicked_users,
-                "failed_to_kick_users": failed_to_kick_users,
-                "local_aliases": aliases_for_room,
-                "new_room_id": new_room_id,
-            },
-        )
+        return (200, ret)
 
 
 class ListRoomRestServlet(RestServlet):