ircd:Ⓜ️ Add convenience suite to extract creator from event tuple.

include/ircd/m/creator.h

@@ -0,0 +1,79 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2023 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_M_CREATOR_H
+
+namespace ircd::m
+{
+	id::user creator(const event &);
+	id::user creation(const event &);
+
+	bool creator(const event &, const id::user &);
+	bool creation(const event &, const id::user &);
+}
+
+/// Events that are not type=m.room.create will return false; the sender field
+/// will be tried if available, otherwise content.creator will be tried.
+inline bool
+ircd::m::creation(const event &event,
+                  const id::user &user)
+{
+	if(json::get<"type"_>(event) != "m.room.create")
+		return false;
+
+	return creator(event, user);
+}
+
+/// The sender field will be tried if available, otherwise content.creator will
+/// be tried.
+inline bool
+ircd::m::creator(const event &event,
+                 const id::user &user)
+{
+	assert(defined(user));
+	if(likely(defined(json::get<"sender"_>(event))))
+		if(json::get<"sender"_>(event) == user)
+			return true;
+
+	const json::string creator
+	{
+		json::get<"content"_>(event).get("creator")
+	};
+
+	return creator == user;
+}
+
+/// Events that are not type=m.room.create will return empty; the sender
+/// will be tried if available, otherwise content.creator will be tried.
+inline ircd::m::id::user
+ircd::m::creation(const event &event)
+{
+	if(json::get<"type"_>(event) != "m.room.create")
+		return id::user{};
+
+	return creator(event);
+}
+
+/// The sender will be tried if available, otherwise content.creator will be
+/// tried.
+inline ircd::m::id::user
+ircd::m::creator(const event &event)
+{
+	if(likely(defined(json::get<"sender"_>(event))))
+		return json::get<"sender"_>(event);
+
+	const json::string creator
+	{
+		json::get<"content"_>(event).get("creator")
+	};
+
+	return creator;
+}

include/ircd/m/m.h

@@ -63,6 +63,7 @@ namespace ircd::m
 #include "device.h"
 #include "push.h"
 #include "createroom.h"
+#include "creator.h"
 #include "txn.h"
 #include "relates.h"
 #include "room/room.h"

matrix/room.cc

@@ -775,6 +775,7 @@ ircd::m::creator(const id::room &room_id)
 {
 	// Query the sender field of the event to get the creator. This is for
 	// future compatibility if the content.creator field gets eliminated.
+	// If the sender gets eliminated instead, include "content" in the keys.
 	static const event::fetch::opts fopts
 	{
 		event::keys::include {"sender"}
@@ -789,10 +790,7 @@ ircd::m::creator(const id::room &room_id)
 	state.get("m.room.create", "", [&ret]
 	(const m::event &event)
 	{
-		ret = user::id
-		{
-			json::get<"sender"_>(event)
-		};
+		ret = m::creator(event);
 	});
 
 	return ret;