Do idna_to_ascii when building own response.
local st = require "util.stanza";
require "core.discomanager".set("ping", "urn:xmpp:ping");
module:add_iq_handler({"c2s", "s2sin"}, "urn:xmpp:ping",
function(session, stanza)
if stanza.attr.type == "get" then
session.send(st.reply(stanza));
end
end);