From 025c2df752de4ef7f5e672630dff332c40235ba6 Mon Sep 17 00:00:00 2001
From: Devin Ragotzy <devin.ragotzy@gmail.com>
Date: Wed, 26 Aug 2020 11:04:30 -0400
Subject: [PATCH] Allow join room creator only if create event has no
 prev_events

---
 src/event_auth.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/event_auth.rs b/src/event_auth.rs
index 4b071599..9e780860 100644
--- a/src/event_auth.rs
+++ b/src/event_auth.rs
@@ -292,7 +292,9 @@ pub fn is_membership_change_allowed(
         if let Some(create) = auth_events.get(&(EventType::RoomCreate, Some("".into()))) {
             if let Ok(create_ev) = create.deserialize_content::<room::create::CreateEventContent>()
             {
-                if user.state_key == Some(create_ev.creator.to_string()) {
+                if user.state_key == Some(create_ev.creator.to_string())
+                    && create.prev_event_ids().is_empty()
+                {
                     tracing::debug!("m.room.member event allowed via m.room.create");
                     return Ok(true);
                 }