Add a standard role to all users logged in by IP

We need a standard role for all users logged in by IP. I added the following function to get the role.

function ip_login_get_role_for_ip_login($role_name = 'IP login')
    {
    $role = db_select('role', 'r')
        ->fields('r', array('rid', 'name'))
        ->condition('name', $role_name)
        ->execute()->fetch();
    return array($role->rid => $role->name);
    }

I found spots to add the role and remember the role. In this example, $new_roles has some roles added in by other code. The actual locations are lost in a number of other code modifications.

define('IP_LOGIN_ROLE', 'ip_login_role'); // Extra role for users logged in purely by IP Login.
if (!isset($_SESSION[IP_LOGIN_ROLE]))
    {
    $_SESSION[IP_LOGIN_ROLE] = ip_login_get_role_for_ip_login();
    }
if (!empty($_SESSION[IP_LOGIN_ROLE]))
    {
    $new_roles = $_SESSION[IP_LOGIN_ROLE];
    }
foreach($new_roles as $role_id => $role_name)
    {
    if(!isset($user->roles[$role_id]))
        {
        $user->roles[$role_id] = $role_name;
        }
    }