State-reset and security mitigations.

Upgrade Ruma to present.

The following are intentionally benign for activation in a later commit:

- Hydra backports not default.
- Room version 12 not default.
- Room version 12 not listed as stable.

Do not enable them manually or you can brick your database.

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/matrix/room_version.rs

@@ -0,0 +1,23 @@
+use ruma::{RoomVersionId, events::room::create::RoomCreateEventContent};
+pub use ruma::{RoomVersionId as RoomVersion, room_version_rules::RoomVersionRules};
+
+use crate::{Result, err, matrix::Event};
+
+pub fn rules(room_version_id: &RoomVersionId) -> Result<RoomVersionRules> {
+	room_version_id.rules().ok_or_else(|| {
+		err!(Request(UnsupportedRoomVersion(
+			"Unknown or unsupported room version {room_version_id:?}.",
+		)))
+	})
+}
+
+pub fn from_create_event<Pdu: Event>(create_event: &Pdu) -> Result<RoomVersionId> {
+	let content: RoomCreateEventContent = create_event.get_content()?;
+	Ok(from_create_content(&content).clone())
+}
+
+#[inline]
+#[must_use]
+pub fn from_create_content(content: &RoomCreateEventContent) -> &RoomVersionId {
+	&content.room_version
+}