Levels in login servlet

Question

I am about to extend my login servlet.
First I want to give each user different levels.
Example I have 4 options
- Watch topics
- Modify topics
- Delete topics
- Create new user
User 1 is allowed to do all 4 options.
User 2 is only allowed to use 1st option
User 3 is allowed to use top 3 options
User 4 is allowed to use top 2 options
Which way is the best way to build such 'check'?
Second, I need to have some check added to check if the origin of the login form, is from the same server .
thanks
Andreas

Answer 1

OK, create your role keys like this:
int watchRole = 1; // binary 0001
int modifyRole = 2; // binary 0010
int deleteRole = 4; // binary 0100
int createRole = 8; // binary 1000Your user's all have a 'mask' as well, which would be stored in your database alongside their username and password. If the user joe needs 'watch' and 'modify' permissions, his mask would be 1+2=3:
int userKey = 3; // binary 0011When an action requiring 'modify' permissions is attempted, the following operation will check authentication:
if (userKey & modifyRole == modifyRole) {
// user is authenticated
} else {
// user is NOT authenticated
}So Joe would be successfully authenticated.
You can use different binary AND/OR logic to perform different operations or checks:
(roleKey | roleKey) // combines permissions
(userKey & roleKey) // checks permissions
(userKey | roleKey) // adds permissions
(userKey & !roleKey) // deletes permissionsEg to add 'delete' permissions to Joe you do this:
userKey = userKey | deleteRole;and the resultant userKey now has delete permissions.
I'd recommend googling for binary logic if you're still unsure about how this all works.
Hope that helps.
--Jon