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<?php
require_once($CFG->dirroot . '/enrol/lti/ims-blti/OAuth.php');
require_once($CFG->dirroot . '/enrol/lti/ims-blti/TrivialOAuthDataStore.php');
// Returns true if this is a Basic LTI message
// with minimum values to meet the protocol
function is_basic_lti_request() {
$good_message_type = $_REQUEST["lti_message_type"] == "basic-lti-launch-request";
$good_lti_version = ($_REQUEST["lti_version"] == "LTI-1p0" or $_REQUEST["lti_version"] == "LTI-1.0");
$good_lti_version = $good_lti_version || ($_REQUEST["lti_version"] == "LTI-2p0" or $_REQUEST["lti_version"] == "LTI-2.0");
$resource_link_id = $_REQUEST["resource_link_id"];
if ($good_message_type and $good_lti_version and isset($resource_link_id) ) return(true);
return false;
}
// Basic LTI Class that does the setup and provides utility
// functions
class BLTI {
public $valid = false;
public $complete = false;
public $message = false;
public $basestring = false;
public $info = false;
public $row = false;
public $context_id = false; // Override context_id
function __construct($parm=false, $usesession=true, $doredirect=true) {
// If this request is not an LTI Launch, either
// give up or try to retrieve the context from session
if ( ! is_basic_lti_request() ) {
if ( $usesession === false ) return;
if ( strlen(session_id()) > 0 ) {
$row = $_SESSION['_basiclti_lti_row'];
if ( isset($row) ) $this->row = $row;
$context_id = $_SESSION['_basiclti_lti_context_id'];
if ( isset($context_id) ) $this->context_id = $context_id;
$info = $_SESSION['_basic_lti_context'];
if ( isset($info) ) {
$this->info = $info;
$this->valid = true;
return;
}
$this->message = "Could not find context in session";
return;
}
$this->message = "Session not available";
return;
}
// Insure we have a valid launch
if ( empty($_REQUEST["oauth_consumer_key"]) ) {
$this->message = "Missing oauth_consumer_key in request";
return;
}
$oauth_consumer_key = $_REQUEST["oauth_consumer_key"];
// Find the secret - either form the parameter as a string or
// look it up in a database from parameters we are given
$secret = false;
$row = false;
if ( is_string($parm) ) {
$secret = $parm;
} else if ( ! is_array($parm) ) {
$this->message = "Constructor requires a secret or database information.";
return;
}
// Verify the message signature
$store = new TrivialOAuthDataStore();
$store->add_consumer($oauth_consumer_key, $secret);
$server = new OAuthServer($store);
$method = new OAuthSignatureMethod_HMAC_SHA1();
$server->add_signature_method($method);
$request = OAuthRequest::from_request();
$this->basestring = $request->get_signature_base_string();
try {
$server->verify_request($request);
$this->valid = true;
} catch (Exception $e) {
$this->message = $e->getMessage();
return;
}
// Store the launch information in the session for later
$newinfo = array();
foreach($_POST as $key => $value ) {
if ( $key == "basiclti_submit" ) continue;
if ( strpos($key, "oauth_") === false ) {
$newinfo[$key] = $value;
continue;
}
if ( $key == "oauth_consumer_key" ) {
$newinfo[$key] = $value;
continue;
}
}
//Added abertranb to decode base 64 20120801
if (isset($newinfo['custom_lti_message_encoded_base64']) && $newinfo['custom_lti_message_encoded_base64']==1){
$newinfo = $this->decodeBase64($newinfo);
}
$this->info = $newinfo;
if ( $usesession == true and strlen(session_id()) > 0 ) {
$_SESSION['_basic_lti_context'] = $this->info;
unset($_SESSION['_basiclti_lti_row']);
unset($_SESSION['_basiclti_lti_context_id']);
if ( $this->row ) $_SESSION['_basiclti_lti_row'] = $this->row;
if ( $this->context_id ) $_SESSION['_basiclti_lti_context_id'] = $this->context_id;
}
if ( $this->valid && $doredirect ) {
$this->redirect();
$this->complete = true;
}
}
function addSession($location) {
if ( ini_get('session.use_cookies') == 0 ) {
if ( strpos($location,'?') > 0 ) {
$location = $location . '&';
} else {
$location = $location . '?';
}
$location = $location . session_name() . '=' . session_id();
}
return $location;
}
function isInstructor() {
$roles = $this->info['roles'];
$roles = strtolower($roles);
if ( ! ( strpos($roles,"instructor") === false ) ) return true;
if ( ! ( strpos($roles,"administrator") === false ) ) return true;
return false;
}
function getUserEmail() {
# set default email in the event privacy settings don't pass in email.
$email = $this->info['user_id'] . "@ltiuser.com";
if ( isset($this->info['lis_person_contact_email_primary']) ) $email = $this->info['lis_person_contact_email_primary'];
# Sakai Hack
if ( isset($this->info['lis_person_contact_emailprimary']) ) $email = $this->info['lis_person_contact_emailprimary'];
return $email;
}
function getUserShortName() {
$email = $this->getUserEmail();
$givenname = $this->info['lis_person_name_given'];
$familyname = $this->info['lis_person_name_family'];
$fullname = $this->info['lis_person_name_full'];
if ( strlen($email) > 0 ) return $email;
if ( strlen($givenname) > 0 ) return $givenname;
if ( strlen($familyname) > 0 ) return $familyname;
return $this->getUserName();
}
function getUserName() {
$givenname = $this->info['lis_person_name_given'];
$familyname = $this->info['lis_person_name_family'];
$fullname = $this->info['lis_person_name_full'];
if ( strlen($fullname) > 0 ) return $fullname;
if ( strlen($familyname) > 0 and strlen($givenname) > 0 ) return $givenname + $familyname;
if ( strlen($givenname) > 0 ) return $givenname;
if ( strlen($familyname) > 0 ) return $familyname;
return $this->getUserEmail();
}
function getUserKey() {
$oauth = $this->info['oauth_consumer_key'];
$id = $this->info['user_id'];
if ( strlen($id) > 0 and strlen($oauth) > 0 ) return $oauth . ':' . $id;
return false;
}
function getUserImage() {
$image = $this->info['user_image'];
if ( strlen($image) > 0 ) return $image;
$email = $this->getUserEmail();
if ( $email === false ) return false;
$size = 40;
$grav_url = $_SERVER['HTTPS'] ? 'https://' : 'http://';
$grav_url = $grav_url . "www.gravatar.com/avatar.php?gravatar_id=".md5( strtolower($email) )."&size=".$size;
return $grav_url;
}
function getResourceKey() {
$oauth = $this->info['oauth_consumer_key'];
$id = $this->info['resource_link_id'];
if ( strlen($id) > 0 and strlen($oauth) > 0 ) return $oauth . ':' . $id;
return false;
}
function getResourceTitle() {
$title = $this->info['resource_link_title'];
if ( strlen($title) > 0 ) return $title;
return false;
}
function getConsumerKey() {
$oauth = $this->info['oauth_consumer_key'];
return $oauth;
}
function getCourseKey() {
if ( $this->context_id ) return $this->context_id;
$oauth = $this->info['oauth_consumer_key'];
$id = $this->info['context_id'];
if ( strlen($id) > 0 and strlen($oauth) > 0 ) return $oauth . ':' . $id;
return false;
}
function getCourseName() {
$label = $this->info['context_label'];
$title = $this->info['context_title'];
$id = $this->info['context_id'];
if ( strlen($label) > 0 ) return $label;
if ( strlen($title) > 0 ) return $title;
if ( strlen($id) > 0 ) return $id;
return false;
}
// TODO: Add javasript version if headers are already sent
function redirect() {
$host = $_SERVER['HTTP_HOST'];
$uri = $_SERVER['PHP_SELF'];
$location = $_SERVER['HTTPS'] ? 'https://' : 'http://';
$location = $location . $host . $uri;
$location = $this->addSession($location);
header("Location: $location");
}
function dump() {
if ( ! $this->valid or $this->info == false ) return "Context not valid\n";
$ret = "";
if ( $this->isInstructor() ) {
$ret .= "isInstructor() = true\n";
} else {
$ret .= "isInstructor() = false\n";
}
$ret .= "getUserKey() = ".$this->getUserKey()."\n";
$ret .= "getUserEmail() = ".$this->getUserEmail()."\n";
$ret .= "getUserShortName() = ".$this->getUserShortName()."\n";
$ret .= "getUserName() = ".$this->getUserName()."\n";
$ret .= "getUserImage() = ".$this->getUserImage()."\n";
$ret .= "getResourceKey() = ".$this->getResourceKey()."\n";
$ret .= "getResourceTitle() = ".$this->getResourceTitle()."\n";
$ret .= "getCourseName() = ".$this->getCourseName()."\n";
$ret .= "getCourseKey() = ".$this->getCourseKey()."\n";
$ret .= "getConsumerKey() = ".$this->getConsumerKey()."\n";
return $ret;
}
/**
* Data submitter are in base64 then we have to decode
* @author Antoni Bertran (antoni@tresipunt.com)
* @param $info array
* @date 20120801
*/
function decodeBase64($info) {
$keysNoEncode = array("lti_version", "lti_message_type", "tool_consumer_instance_description", "tool_consumer_instance_guid", "oauth_consumer_key", "custom_lti_message_encoded_base64", "oauth_nonce", "oauth_version", "oauth_callback", "oauth_timestamp", "basiclti_submit", "oauth_signature_method", "ext_ims_lis_memberships_id", "ext_ims_lis_memberships_url");
foreach ($info as $key => $item){
if (!in_array($key, $keysNoEncode))
$info[$key] = base64_decode($item);
}
return $info;
}
}
?>