initial implementation of banning room IDs

takes a full room ID, evicts all our users from that room,
adds room ID to banned room IDs metadata db table, and
forbids any new local users from attempting to join it.

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/api/client_server/membership.rs

@@ -49,6 +49,13 @@ pub async fn join_room_by_id_route(
 ) -> Result<join_room_by_id::v3::Response> {
     let sender_user = body.sender_user.as_ref().expect("user is authenticated");
 
+    if services().rooms.metadata.is_banned(&body.room_id)? {
+        return Err(Error::BadRequest(
+            ErrorKind::Forbidden,
+            "This room is banned on this homeserver.",
+        ));
+    }
+
     let mut servers = Vec::new(); // There is no body.server_name for /roomId/join
     servers.extend(
         services()
@@ -90,6 +97,13 @@ pub async fn join_room_by_id_or_alias_route(
 
     let (servers, room_id) = match OwnedRoomId::try_from(body.room_id_or_alias) {
         Ok(room_id) => {
+            if services().rooms.metadata.is_banned(&room_id)? {
+                return Err(Error::BadRequest(
+                    ErrorKind::Forbidden,
+                    "This room is banned on this homeserver.",
+                ));
+            }
+
             let mut servers = body.server_name.clone();
             servers.extend(
                 services()
@@ -112,6 +126,13 @@ pub async fn join_room_by_id_or_alias_route(
         Err(room_alias) => {
             let response = get_alias_helper(room_alias).await?;
 
+            if services().rooms.metadata.is_banned(&response.room_id)? {
+                return Err(Error::BadRequest(
+                    ErrorKind::Forbidden,
+                    "This room is banned on this homeserver.",
+                ));
+            }
+
             (response.servers, response.room_id)
         }
     };