use AnyEvent::XMPP::Ext::MUC;

sub retr_connected_users {
        my @data = map { chomp; s/@.*//; $_ } (`some command`);
        return @data;
}

$muc->reg_cb(
        message => sub {
                my ( undef, undef, $msg ) = @_;

                my @inter = retr_connected_users();
                foreach my $user(@inter){
                        AnyEvent::XMPP::IM::Message->new (
                                body => construct_body($msg->body, $from),
                                to   => "$user\@" . HOST,
                                type => "chat",
                        )->send($conn);
                }
        },
);