1 local jid = require "util.jid";

     2 local st = require "util.stanza";

     3 

     4 local nick_pattern = module:get_option_string("muc_restrict_nick_pattern", "^%w+$");

     5 

     6 module:hook("muc-occupant-pre-join", function (event)

     7 	local nick = jid.resource(event.occupant.nick);

     8 	if not nick:match(nick_pattern) then

     9 		local reply = st.error_reply(event.stanza, "modify", "policy-violation", "Unacceptable nickname, please try another");

    10 		module:send(reply);

    11 		return true;

    12 	end

    13 end);