--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_muc_reserve_nick_pattern/README.markdown	Mon Feb 20 13:42:13 2023 -0500
@@ -0,0 +1,23 @@
+---
+labels:
+- 'Stage-Alpha'
+summary: 'Require MUC occupant nicknames to no match some patterns'
+---
+
+Introduction
+============
+
+This checks the nickname of a joining user against a configurable list of
+[Lua patterns](https://www.lua.org/manual/5.2/manual.html#6.4.1), and prevents
+them from joining if it matches any of them.
+
+Configuration
+=============
+
+There is a single configuration option, `muc_reserve_nick_patterns` and the
+default is `{}` - i.e. allow everything.
+
+Compatibility
+=============
+
+Requires Prosody 0.11 or higher.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_muc_reserve_nick_pattern/mod_muc_reserve_nick_pattern.lua	Mon Feb 20 13:42:13 2023 -0500
@@ -0,0 +1,15 @@
+local jid = require "util.jid";
+local st = require "util.stanza";
+
+local nick_patterns = module:get_option_array("muc_reserve_nick_patterns", {});
+
+module:hook("muc-occupant-pre-join", function (event)
+	local nick = jid.resource(event.occupant.nick);
+	for k, nick_pattern in pairs(nick_patterns) do
+		if nick:match(nick_pattern) then
+			local reply = st.error_reply(event.stanza, "modify", "conflict", "Unacceptable nickname, please try another");
+			module:send(reply);
+			return true;
+		end
+	end
+end);