[Summary view]

   1  <?php
   2  
   3  require_once($CFG->dirroot . '/enrol/lti/ims-blti/OAuth.php');
   4  require_once($CFG->dirroot . '/enrol/lti/ims-blti/TrivialOAuthDataStore.php');
   5  
   6  // Returns true if this is a Basic LTI message
   7  // with minimum values to meet the protocol
   8  function is_basic_lti_request() {
   9     $good_message_type = $_REQUEST["lti_message_type"] == "basic-lti-launch-request";
  10     $good_lti_version = ($_REQUEST["lti_version"] == "LTI-1p0" or $_REQUEST["lti_version"] == "LTI-1.0");
  11     $good_lti_version = $good_lti_version || ($_REQUEST["lti_version"] == "LTI-2p0" or $_REQUEST["lti_version"] == "LTI-2.0");
  12     $resource_link_id = $_REQUEST["resource_link_id"];
  13     if ($good_message_type and $good_lti_version and isset($resource_link_id) ) return(true);
  14     return false;
  15  }
  16  
  17  // Basic LTI Class that does the setup and provides utility
  18  // functions
  19  class BLTI {
  20  
  21      public $valid = false;
  22      public $complete = false;
  23      public $message = false;
  24      public $basestring = false;
  25      public $info = false;
  26      public $row = false;
  27      public $context_id = false;  // Override context_id
  28  
  29      function __construct($parm=false, $usesession=true, $doredirect=true) {
  30  
  31  
  32          // If this request is not an LTI Launch, either
  33          // give up or try to retrieve the context from session
  34          if ( ! is_basic_lti_request() ) {
  35  
  36              if ( $usesession === false ) return;
  37  
  38              if ( strlen(session_id()) > 0 ) {
  39                  $row = $_SESSION['_basiclti_lti_row'];
  40                  if ( isset($row) ) $this->row = $row;
  41                  $context_id = $_SESSION['_basiclti_lti_context_id'];
  42                  if ( isset($context_id) ) $this->context_id = $context_id;
  43                  $info = $_SESSION['_basic_lti_context'];
  44                  if ( isset($info) ) {
  45                      $this->info = $info;
  46                      $this->valid = true;
  47                      return;
  48                  }
  49                  $this->message = "Could not find context in session";
  50                  return;
  51              }
  52              $this->message = "Session not available";
  53              return;
  54          }
  55          // Insure we have a valid launch
  56          if ( empty($_REQUEST["oauth_consumer_key"]) ) {
  57              $this->message = "Missing oauth_consumer_key in request";
  58              return;
  59          }
  60          $oauth_consumer_key = $_REQUEST["oauth_consumer_key"];
  61  
  62          // Find the secret - either form the parameter as a string or
  63          // look it up in a database from parameters we are given
  64          $secret = false;
  65          $row = false;
  66          if ( is_string($parm) ) {
  67              $secret = $parm;
  68          } else if ( ! is_array($parm) ) {
  69              $this->message = "Constructor requires a secret or database information.";
  70              return;
  71          }
  72  
  73          // Verify the message signature
  74          $store = new TrivialOAuthDataStore();
  75          $store->add_consumer($oauth_consumer_key, $secret);
  76  
  77          $server = new OAuthServer($store);
  78  
  79          $method = new OAuthSignatureMethod_HMAC_SHA1();
  80          $server->add_signature_method($method);
  81          $request = OAuthRequest::from_request();
  82  
  83          $this->basestring = $request->get_signature_base_string();
  84          try {
  85              $server->verify_request($request);
  86              $this->valid = true;
  87          } catch (Exception $e) {
  88              $this->message = $e->getMessage();
  89              return;
  90          }
  91          // Store the launch information in the session for later
  92          $newinfo = array();
  93          foreach($_POST as $key => $value ) {
  94              if ( $key == "basiclti_submit" ) continue;
  95              if ( strpos($key, "oauth_") === false ) {
  96                  $newinfo[$key] = $value;
  97                  continue;
  98              }
  99              if ( $key == "oauth_consumer_key" ) {
 100                  $newinfo[$key] = $value;
 101                  continue;
 102              }
 103          }
 104          //Added abertranb to decode base 64 20120801
 105          if (isset($newinfo['custom_lti_message_encoded_base64']) && $newinfo['custom_lti_message_encoded_base64']==1){
 106              $newinfo = $this->decodeBase64($newinfo);
 107          }
 108  
 109          $this->info = $newinfo;
 110  
 111          if ( $usesession == true and strlen(session_id()) > 0 ) {
 112               $_SESSION['_basic_lti_context'] = $this->info;
 113               unset($_SESSION['_basiclti_lti_row']);
 114               unset($_SESSION['_basiclti_lti_context_id']);
 115               if ( $this->row ) $_SESSION['_basiclti_lti_row'] = $this->row;
 116               if ( $this->context_id ) $_SESSION['_basiclti_lti_context_id'] = $this->context_id;
 117          }
 118  
 119          if ( $this->valid && $doredirect ) {
 120              $this->redirect();
 121              $this->complete = true;
 122          }
 123      }
 124  
 125      function addSession($location) {
 126          if ( ini_get('session.use_cookies') == 0 ) {
 127              if ( strpos($location,'?') > 0 ) {
 128                 $location = $location . '&';
 129              } else {
 130                 $location = $location . '?';
 131              }
 132              $location = $location . session_name() . '=' . session_id();
 133          }
 134          return $location;
 135      }
 136  
 137      function isInstructor() {
 138          $roles = $this->info['roles'];
 139          $roles = strtolower($roles);
 140          if ( ! ( strpos($roles,"instructor") === false ) ) return true;
 141          if ( ! ( strpos($roles,"administrator") === false ) ) return true;
 142          return false;
 143      }
 144  
 145      function getUserEmail() {
 146          # set default email in the event privacy settings don't pass in email.
 147          $email = $this->info['user_id'] . "@ltiuser.com";
 148          if ( isset($this->info['lis_person_contact_email_primary']) ) $email = $this->info['lis_person_contact_email_primary'];
 149          # Sakai Hack
 150          if ( isset($this->info['lis_person_contact_emailprimary']) ) $email = $this->info['lis_person_contact_emailprimary'];
 151          return $email;
 152      }
 153  
 154      function getUserShortName() {
 155          $email = $this->getUserEmail();
 156          $givenname = $this->info['lis_person_name_given'];
 157          $familyname = $this->info['lis_person_name_family'];
 158          $fullname = $this->info['lis_person_name_full'];
 159          if ( strlen($email) > 0 ) return $email;
 160          if ( strlen($givenname) > 0 ) return $givenname;
 161          if ( strlen($familyname) > 0 ) return $familyname;
 162          return $this->getUserName();
 163      }
 164  
 165      function getUserName() {
 166          $givenname = $this->info['lis_person_name_given'];
 167          $familyname = $this->info['lis_person_name_family'];
 168          $fullname = $this->info['lis_person_name_full'];
 169          if ( strlen($fullname) > 0 ) return $fullname;
 170          if ( strlen($familyname) > 0 and strlen($givenname) > 0 ) return $givenname + $familyname;
 171          if ( strlen($givenname) > 0 ) return $givenname;
 172          if ( strlen($familyname) > 0 ) return $familyname;
 173          return $this->getUserEmail();
 174      }
 175  
 176      function getUserKey() {
 177          $oauth = $this->info['oauth_consumer_key'];
 178          $id = $this->info['user_id'];
 179          if ( strlen($id) > 0 and strlen($oauth) > 0 ) return $oauth . ':' . $id;
 180          return false;
 181      }
 182  
 183      function getUserImage() {
 184          $image = $this->info['user_image'];
 185          if ( strlen($image) > 0 ) return $image;
 186          $email = $this->getUserEmail();
 187          if ( $email === false ) return false;
 188          $size = 40;
 189          $grav_url = $_SERVER['HTTPS'] ? 'https://' : 'http://';
 190          $grav_url = $grav_url . "www.gravatar.com/avatar.php?gravatar_id=".md5( strtolower($email) )."&size=".$size;
 191          return $grav_url;
 192      }
 193  
 194      function getResourceKey() {
 195          $oauth = $this->info['oauth_consumer_key'];
 196          $id = $this->info['resource_link_id'];
 197          if ( strlen($id) > 0 and strlen($oauth) > 0 ) return $oauth . ':' . $id;
 198          return false;
 199      }
 200  
 201      function getResourceTitle() {
 202          $title = $this->info['resource_link_title'];
 203          if ( strlen($title) > 0 ) return $title;
 204          return false;
 205      }
 206  
 207      function getConsumerKey() {
 208          $oauth = $this->info['oauth_consumer_key'];
 209          return $oauth;
 210      }
 211  
 212      function getCourseKey() {
 213          if ( $this->context_id ) return $this->context_id;
 214          $oauth = $this->info['oauth_consumer_key'];
 215          $id = $this->info['context_id'];
 216          if ( strlen($id) > 0 and strlen($oauth) > 0 ) return $oauth . ':' . $id;
 217          return false;
 218      }
 219  
 220      function getCourseName() {
 221          $label = $this->info['context_label'];
 222          $title = $this->info['context_title'];
 223          $id = $this->info['context_id'];
 224          if ( strlen($label) > 0 ) return $label;
 225          if ( strlen($title) > 0 ) return $title;
 226          if ( strlen($id) > 0 ) return $id;
 227          return false;
 228      }
 229  
 230      // TODO: Add javasript version if headers are already sent
 231      function redirect() {
 232              $host = $_SERVER['HTTP_HOST'];
 233              $uri = $_SERVER['PHP_SELF'];
 234              $location = $_SERVER['HTTPS'] ? 'https://' : 'http://';
 235              $location = $location . $host . $uri;
 236              $location = $this->addSession($location);
 237              header("Location: $location");
 238      }
 239  
 240      function dump() {
 241          if ( ! $this->valid or $this->info == false ) return "Context not valid\n";
 242          $ret = "";
 243          if ( $this->isInstructor() ) {
 244              $ret .= "isInstructor() = true\n";
 245          } else {
 246              $ret .= "isInstructor() = false\n";
 247          }
 248          $ret .= "getUserKey() = ".$this->getUserKey()."\n";
 249          $ret .= "getUserEmail() = ".$this->getUserEmail()."\n";
 250          $ret .= "getUserShortName() = ".$this->getUserShortName()."\n";
 251          $ret .= "getUserName() = ".$this->getUserName()."\n";
 252          $ret .= "getUserImage() = ".$this->getUserImage()."\n";
 253          $ret .= "getResourceKey() = ".$this->getResourceKey()."\n";
 254          $ret .= "getResourceTitle() = ".$this->getResourceTitle()."\n";
 255          $ret .= "getCourseName() = ".$this->getCourseName()."\n";
 256          $ret .= "getCourseKey() = ".$this->getCourseKey()."\n";
 257          $ret .= "getConsumerKey() = ".$this->getConsumerKey()."\n";
 258          return $ret;
 259      }
 260  
 261      /**
 262       * Data submitter are in base64 then we have to decode
 263       * @author Antoni Bertran (antoni@tresipunt.com)
 264       * @param $info array
 265       * @date 20120801
 266       */
 267       function decodeBase64($info) {
 268           $keysNoEncode = array("lti_version", "lti_message_type", "tool_consumer_instance_description", "tool_consumer_instance_guid", "oauth_consumer_key", "custom_lti_message_encoded_base64", "oauth_nonce", "oauth_version", "oauth_callback", "oauth_timestamp", "basiclti_submit", "oauth_signature_method", "ext_ims_lis_memberships_id", "ext_ims_lis_memberships_url");
 269           foreach ($info as $key => $item){
 270               if (!in_array($key, $keysNoEncode))
 271                  $info[$key] = base64_decode($item);
 272           }
 273          return $info;
 274       }
 275  
 276  }
 277  
 278  ?>