If the remember me checkbox is checked you set a cookie on the user's system with a random string. E.g.:
$cookie = array(
'name' => 'remember_me_token',
'value' => 'Random string',
'expire' => '1209600', // Two weeks
'domain' => '.your_domain.com',
'path' => '/'
);
set_cookie($cookie);
You also save this random string in the users
table, e.g. in the column remember_me_token
.
Now, when a user (who is not yet logged in) tries to access a page that requires authentication:
- you check if there is a cookie by the name of
remember_me
token on his system
- if it's there, you check the database if there is a record with the same value
- if so, you recreate this user's session (this means they are logged in)
- show the page they were visiting
If one of the requirements above is not met, you redirect them to the login page.
For security reasons you may want to renew the random remember_me_token
every time the user logs in. You can also update the expiry date of the cookie every time the user logs in. This way he will stay logged in.
It would be too much work to write all the code for you, but I hope this helps you to implement this functionality yourself. Please comment if you have any questions. Good luck.