state-res: Add RoomVersion::V11

According to MSC3820

crates/ruma-state-res/CHANGELOG.md

@@ -1,5 +1,9 @@
 # [unreleased]
 
+Improvements:
+
+- Add `RoomVersion::V11` according to MSC3820
+
 # 0.9.1
 
 No changes for this version

crates/ruma-state-res/src/event_auth.rs

@@ -15,7 +15,10 @@ use ruma_common::{
     serde::{Base64, Raw},
     OwnedUserId, RoomVersionId, UserId,
 };
-use serde::{de::IgnoredAny, Deserialize};
+use serde::{
+    de::{Error as _, IgnoredAny},
+    Deserialize,
+};
 use serde_json::{from_str as from_json_str, value::RawValue as RawJsonValue};
 use tracing::{debug, error, info, warn};
 
@@ -175,10 +178,12 @@ pub fn auth_check<E: Event>(
             return Ok(false);
         }
 
-        // If content has no creator field, reject
-        if content.creator.is_none() {
-            warn!("no creator field found in m.room.create content");
-            return Ok(false);
+        if !room_version.use_room_create_sender {
+            // If content has no creator field, reject
+            if content.creator.is_none() {
+                warn!("no creator field found in m.room.create content");
+                return Ok(false);
+            }
         }
 
         info!("m.room.create event was allowed");
@@ -343,11 +348,19 @@ pub fn auth_check<E: Event>(
         }
     } else {
         // If no power level event found the creator gets 100 everyone else gets 0
-        #[allow(deprecated)]
-        from_json_str::<RoomCreateEventContent>(room_create_event.content().get())
-            .ok()
-            .and_then(|create| (create.creator.unwrap() == *sender).then(|| int!(100)))
-            .unwrap_or_default()
+        let is_creator = if room_version.use_room_create_sender {
+            room_create_event.sender() == sender
+        } else {
+            #[allow(deprecated)]
+            from_json_str::<RoomCreateEventContent>(room_create_event.content().get())
+                .is_ok_and(|create| create.creator.unwrap() == *sender)
+        };
+
+        if is_creator {
+            int!(100)
+        } else {
+            int!(0)
+        }
     };
 
     // Allow if and only if sender's current power level is greater than
@@ -531,12 +544,21 @@ fn valid_membership_change(
             let no_more_prev_events = prev_events.next().is_none();
 
             if prev_event_is_create_event && no_more_prev_events {
-                let create_content =
-                    from_json_str::<RoomCreateEventContent>(create_room.content().get())?;
+                let is_creator = if room_version.use_room_create_sender {
+                    let creator = create_room.sender();
 
-                #[allow(deprecated)]
-                let creator = create_content.creator.unwrap();
-                if creator == sender && creator == target_user {
+                    creator == sender && creator == target_user
+                } else {
+                    #[allow(deprecated)]
+                    let creator =
+                        from_json_str::<RoomCreateEventContent>(create_room.content().get())?
+                            .creator
+                            .ok_or_else(|| serde_json::Error::missing_field("creator"))?;
+
+                    creator == sender && creator == target_user
+                };
+
+                if is_creator {
                     return Ok(true);
                 }
             }

crates/ruma-state-res/src/room_version.rs

@@ -74,6 +74,11 @@ pub struct RoomVersion {
     ///
     /// See: [MSC3667](https://github.com/matrix-org/matrix-spec-proposals/pull/3667) for more information.
     pub integer_power_levels: bool,
+    /// Determine the room creator using the `m.room.create` event's `sender`,
+    /// instead of the event content's `creator` field.
+    ///
+    /// See: [MSC2175](https://github.com/matrix-org/matrix-spec-proposals/pull/2175) for more information.
+    pub use_room_create_sender: bool,
 }
 
 impl RoomVersion {
@@ -90,6 +95,7 @@ impl RoomVersion {
         restricted_join_rules: false,
         knock_restricted_join_rule: false,
         integer_power_levels: false,
+        use_room_create_sender: false,
     };
 
     pub const V2: Self = Self { state_res: StateResolutionVersion::V2, ..Self::V1 };
@@ -117,6 +123,8 @@ impl RoomVersion {
     pub const V10: Self =
         Self { knock_restricted_join_rule: true, integer_power_levels: true, ..Self::V9 };
 
+    pub const V11: Self = Self { use_room_create_sender: true, ..Self::V10 };
+
     pub fn new(version: &RoomVersionId) -> Result<Self> {
         Ok(match version {
             RoomVersionId::V1 => Self::V1,
@@ -129,6 +137,7 @@ impl RoomVersion {
             RoomVersionId::V8 => Self::V8,
             RoomVersionId::V9 => Self::V9,
             RoomVersionId::V10 => Self::V10,
+            RoomVersionId::V11 => Self::V11,
             ver => return Err(Error::Unsupported(format!("found version `{ver}`"))),
         })
     }