firebase_rules.json

{
    "rules": {
        "rooms": {
            "$roomid": {
                // You can see people in the room only if you are in it as well
                ".read": "auth != null && data.child('users').hasChild(auth.id)",
                "users": {
                    "$userid": {
                        // You can modify only your own info
                        ".write": "auth != null && $userid == auth.id",

                        // Ensure that all required attributes are there
                        ".validate": "newData.hasChildren(['uuid', 'public_ip', 'peer']) && newData.child('peer').hasChildren(['id'])"

                    }
                },
                "messages": {
                    // You can send message to anybody in the room
                    ".write": "auth != null",
                    "$userid": {
                        // You can read only messages sent to you
                        ".read": "auth != null && $userid == auth.id"
                    }
                }
            }
        }
    }
}