ejabberd XMPP Expert - Erlang Coding, Java, etc

I have an ejabberd XMPP server set up and my own messenger client app. What I want to do is keep my ejabberd XMPP server Proprietary. In other words to have only my app connect to the server, and not to have the server seen or available to anyone else. I am open to suggestions on ideas to achieve this but my initial thought was to have something like the following. When the messenger app (mobile and later web) connects to the XMPP sever, the app will send a "code" that is generated. The server will receive this code and then check it's authenticity by checking with an external SQL database. If that code exists then the app can connect and continue. Else if the code does not exists the app cannot continue. So in summary I am thinking there needs to be a mod to the ejabberd code at the connection stage to handle ; a) obtaining the code b) checking externally to a SQL database to verify that code c) logically allowing or not allowing the connection.