Connecting to Indiana University via CAS Login

iu_cas_login

//Note: I did not write all of this code. Some was provided by IU. I am only showing an efficient method to 
//making sure they are an IU student. I wrote this code for use on the iuifc.org website. Any problems? @liambolling


//You may not need this. I found it helped to make sure to ask for auth.
session_start();
 
//This will send the user everytime to CAS to authenticate. 
//Fixes the whole "I closed my browser but not out of CAS" thing.

function cas_authenticate(){
  $sid = SID; //SESSION ID
 
  //Because SESSIONS are used, I default set it to false to make them login. 
  //Watch out with this. I used it because I just wanted to authenticate that they are a student
  //But if you plan to use CAS for the login method, this is a bad idea most likley.
  $_SESSION['CAS'] = false;
 
  $authenticated = $_SESSION['CAS'];
  //Make sure that your code redirects back to here or else you will get an error.
  $casurl = "www.yourURL.com";
 
  //send user to CAS login if not authenticated
  if (!$authenticated) {
    $_SESSION['LAST_SESSION'] = time(); // update last activity time stamp
    $_SESSION['CAS'] = true;
    echo '<META HTTP-EQUIV="Refresh" Content="0; URL=https://cas.iu.edu/cas/login?cassvc=IU&casurl='.$casurl.'">';
	
    exit;
  }
 
  if ($authenticated) {
    if (isset($_GET["casticket"])) {
      //set up validation URL to ask CAS if ticket is good
      $_url = 'https://cas.iu.edu/cas/validate';
      $cassvc = 'IU';
 
      $params = "cassvc=$cassvc&casticket=$_GET[casticket]&casurl=$casurl";
      $urlNew = "$_url?$params";
 
      //CAS sending response on 2 lines. First line contains "yes" or "no". If "yes", second line contains username (otherwise, it is empty).
      $ch = curl_init();
      $timeout = 5; // set to zero for no timeout
      curl_setopt ($ch, CURLOPT_URL, $urlNew);
      curl_setopt ($ch, CURLOPT_CONNECTTIMEOUT, $timeout);
      ob_start();
      curl_exec($ch);
      curl_close($ch);
      $cas_answer = ob_get_contents();
      ob_end_clean();
      
      //split CAS answer into access and user
      list($access,$user) = split("\n",$cas_answer,2);
      $access = trim($access);
      $user = trim($user);
      
      //set user and session variable if CAS says YES
      if ($access == "yes") {
        $_SESSION['user'] = $user;
      }
      
    } else if (!isset($_SESSION['user'])) { //END GET CAS TICKET
      echo '<META HTTP-EQUIV="Refresh" Content="0; URL=https://cas.iu.edu/cas/login?cassvc=IU&casurl='.$casurl.'">';
    }
  }
}//END CAS FUNCTION
 
cas_authenticate();
 
//gets the username from the SESSION and assigns it to username.
$username = $_SESSION['user'];
$email_address = $_SESSION['email_address'];
 
 
//If you want to block someone from your application, you can add them to here
//or curate a list of users you wish to block.
$users = array("ljbollin");
if(in_array($username, $users)){
  die("Sorry, your account was blacklisted and deleted for misconduct. Please contact IFC if you with to revoke this issue.
");
}


session_destroy();