/**
* Check the authenticity of the LTI launch request.
*
* The consumer, resource link and user objects will be initialised if the request is valid.
*
* @return boolean True if the request has been successfully validated.
*/
private function authenticate()
{
// Get the consumer
$doSaveConsumer = false;
// Check all required launch parameters
$this->ok = isset($_POST['lti_message_type']) && array_key_exists($_POST['lti_message_type'], self::$MESSAGE_TYPES);
if (!$this->ok) {
$this->reason = 'Invalid or missing lti_message_type parameter.';
}
if ($this->ok) {
$this->ok = isset($_POST['lti_version']) && in_array($_POST['lti_version'], self::$LTI_VERSIONS);
if (!$this->ok) {
$this->reason = 'Invalid or missing lti_version parameter.';
}
}
if ($this->ok) {
if ($_POST['lti_message_type'] === 'basic-lti-launch-request') {
$this->ok = isset($_POST['resource_link_id']) && strlen(trim($_POST['resource_link_id'])) > 0;
if (!$this->ok) {
$this->reason = 'Missing resource link ID.';
}
} else {
if ($_POST['lti_message_type'] === 'ContentItemSelectionRequest') {
if (isset($_POST['accept_media_types']) && strlen(trim($_POST['accept_media_types'])) > 0) {
$mediaTypes = array_filter(explode(',', str_replace(' ', '', $_POST['accept_media_types'])), 'strlen');
$mediaTypes = array_unique($mediaTypes);
$this->ok = count($mediaTypes) > 0;
if (!$this->ok) {
$this->reason = 'No accept_media_types found.';
} else {
$this->mediaTypes = $mediaTypes;
}
} else {
$this->ok = false;
}
if ($this->ok && isset($_POST['accept_presentation_document_targets']) && strlen(trim($_POST['accept_presentation_document_targets'])) > 0) {
$documentTargets = array_filter(explode(',', str_replace(' ', '', $_POST['accept_presentation_document_targets'])), 'strlen');
$documentTargets = array_unique($documentTargets);
$this->ok = count($documentTargets) > 0;
if (!$this->ok) {
$this->reason = 'Missing or empty accept_presentation_document_targets parameter.';
} else {
foreach ($documentTargets as $documentTarget) {
$this->ok = $this->checkValue($documentTarget, array('embed', 'frame', 'iframe', 'window', 'popup', 'overlay', 'none'), 'Invalid value in accept_presentation_document_targets parameter: %s.');
if (!$this->ok) {
break;
}
}
if ($this->ok) {
$this->documentTargets = $documentTargets;
}
}
} else {
$this->ok = false;
}
if ($this->ok) {
$this->ok = isset($_POST['content_item_return_url']) && strlen(trim($_POST['content_item_return_url'])) > 0;
if (!$this->ok) {
$this->reason = 'Missing content_item_return_url parameter.';
}
}
} else {
if ($_POST['lti_message_type'] == 'ToolProxyRegistrationRequest') {
$this->ok = isset($_POST['reg_key']) && strlen(trim($_POST['reg_key'])) > 0 && (isset($_POST['reg_password']) && strlen(trim($_POST['reg_password'])) > 0) && (isset($_POST['tc_profile_url']) && strlen(trim($_POST['tc_profile_url'])) > 0) && (isset($_POST['launch_presentation_return_url']) && strlen(trim($_POST['launch_presentation_return_url'])) > 0);
if ($this->debugMode && !$this->ok) {
$this->reason = 'Missing message parameters.';
}
}
}
}
}
$now = time();
// Check consumer key
if ($this->ok && $_POST['lti_message_type'] != 'ToolProxyRegistrationRequest') {
$this->ok = isset($_POST['oauth_consumer_key']);
if (!$this->ok) {
$this->reason = 'Missing consumer key.';
}
if ($this->ok) {
$this->consumer = new ToolConsumer($_POST['oauth_consumer_key'], $this->dataConnector);
$this->ok = !is_null($this->consumer->created);
if (!$this->ok) {
$this->reason = 'Invalid consumer key.';
}
}
if ($this->ok) {
$today = date('Y-m-d', $now);
if (is_null($this->consumer->lastAccess)) {
$doSaveConsumer = true;
} else {
$last = date('Y-m-d', $this->consumer->lastAccess);
$doSaveConsumer = $doSaveConsumer || $last !== $today;
}
$this->consumer->last_access = $now;
try {
$store = new OAuthDataStore($this);
$server = new OAuth\OAuthServer($store);
$method = new OAuth\OAuthSignatureMethod_HMAC_SHA1();
$server->add_signature_method($method);
$request = OAuth\OAuthRequest::from_request();
$res = $server->verify_request($request);
} catch (\Exception $e) {
$this->ok = false;
if (empty($this->reason)) {
if ($this->debugMode) {
$consumer = new OAuth\OAuthConsumer($this->consumer->getKey(), $this->consumer->secret);
$signature = $request->build_signature($method, $consumer, false);
$this->reason = $e->getMessage();
if (empty($this->reason)) {
$this->reason = 'OAuth exception';
}
$this->details[] = 'Timestamp: ' . time();
$this->details[] = "Signature: {$signature}";
$this->details[] = "Base string: {$request->base_string}]";
} else {
$this->reason = 'OAuth signature check failed - perhaps an incorrect secret or timestamp.';
}
}
}
}
if ($this->ok) {
$today = date('Y-m-d', $now);
if (is_null($this->consumer->lastAccess)) {
$doSaveConsumer = true;
} else {
$last = date('Y-m-d', $this->consumer->lastAccess);
$doSaveConsumer = $doSaveConsumer || $last !== $today;
}
$this->consumer->last_access = $now;
if ($this->consumer->protected) {
if (!is_null($this->consumer->consumerGuid)) {
$this->ok = empty($_POST['tool_consumer_instance_guid']) || $this->consumer->consumerGuid === $_POST['tool_consumer_instance_guid'];
if (!$this->ok) {
$this->reason = 'Request is from an invalid tool consumer.';
}
} else {
$this->ok = isset($_POST['tool_consumer_instance_guid']);
if (!$this->ok) {
$this->reason = 'A tool consumer GUID must be included in the launch request.';
}
}
}
if ($this->ok) {
$this->ok = $this->consumer->enabled;
if (!$this->ok) {
$this->reason = 'Tool consumer has not been enabled by the tool provider.';
}
}
if ($this->ok) {
$this->ok = is_null($this->consumer->enableFrom) || $this->consumer->enableFrom <= $now;
if ($this->ok) {
$this->ok = is_null($this->consumer->enableUntil) || $this->consumer->enableUntil > $now;
if (!$this->ok) {
$this->reason = 'Tool consumer access has expired.';
}
} else {
$this->reason = 'Tool consumer access is not yet available.';
}
}
}
// Validate other message parameter values
if ($this->ok) {
if ($_POST['lti_message_type'] === 'ContentItemSelectionRequest') {
if (isset($_POST['accept_unsigned'])) {
$this->ok = $this->checkValue($_POST['accept_unsigned'], array('true', 'false'), 'Invalid value for accept_unsigned parameter: %s.');
}
if ($this->ok && isset($_POST['accept_multiple'])) {
$this->ok = $this->checkValue($_POST['accept_multiple'], array('true', 'false'), 'Invalid value for accept_multiple parameter: %s.');
}
if ($this->ok && isset($_POST['accept_copy_advice'])) {
$this->ok = $this->checkValue($_POST['accept_copy_advice'], array('true', 'false'), 'Invalid value for accept_copy_advice parameter: %s.');
}
if ($this->ok && isset($_POST['auto_create'])) {
$this->ok = $this->checkValue($_POST['auto_create'], array('true', 'false'), 'Invalid value for auto_create parameter: %s.');
}
if ($this->ok && isset($_POST['can_confirm'])) {
$this->ok = $this->checkValue($_POST['can_confirm'], array('true', 'false'), 'Invalid value for can_confirm parameter: %s.');
}
} else {
if (isset($_POST['launch_presentation_document_target'])) {
$this->ok = $this->checkValue($_POST['launch_presentation_document_target'], array('embed', 'frame', 'iframe', 'window', 'popup', 'overlay'), 'Invalid value for launch_presentation_document_target parameter: %s.');
}
}
}
}
if ($this->ok && $_POST['lti_message_type'] === 'ToolProxyRegistrationRequest') {
$this->ok = $_POST['lti_version'] == self::LTI_VERSION2;
if (!$this->ok) {
$this->reason = 'Invalid lti_version parameter';
}
if ($this->ok) {
$http = new HTTPMessage($_POST['tc_profile_url'], 'GET', null, 'Accept: application/vnd.ims.lti.v2.toolconsumerprofile+json');
$this->ok = $http->send();
if (!$this->ok) {
$this->reason = 'Tool consumer profile not accessible.';
} else {
$tcProfile = json_decode($http->response);
$this->ok = !is_null($tcProfile);
if (!$this->ok) {
$this->reason = 'Invalid JSON in tool consumer profile.';
}
}
}
// Check for required capabilities
if ($this->ok) {
$this->consumer = new ToolConsumer($_POST['reg_key'], $this->dataConnector);
$this->consumer->profile = $tcProfile;
$capabilities = $this->consumer->profile->capability_offered;
$missing = array();
foreach ($this->resourceHandlers as $resourceHandler) {
foreach ($resourceHandler->requiredMessages as $message) {
if (!in_array($message->type, $capabilities)) {
$missing[$message->type] = true;
}
}
}
foreach ($this->constraints as $name => $constraint) {
if ($constraint['required']) {
if (!in_array($name, $capabilities) && !in_array($name, array_flip($capabilities))) {
$missing[$name] = true;
}
}
}
if (!empty($missing)) {
ksort($missing);
$this->reason = 'Required capability not offered - \'' . implode('\', \'', array_keys($missing)) . '\'';
$this->ok = false;
}
}
// Check for required services
if ($this->ok) {
foreach ($this->requiredServices as $service) {
foreach ($service->formats as $format) {
if (!$this->findService($format, $service->actions)) {
if ($this->ok) {
$this->reason = 'Required service(s) not offered - ';
$this->ok = false;
} else {
$this->reason .= ', ';
}
$this->reason .= "'{$format}' [" . implode(', ', $service->actions) . ']';
}
}
}
}
if ($this->ok) {
if ($_POST['lti_message_type'] === 'ToolProxyRegistrationRequest') {
$this->consumer->profile = $tcProfile;
$this->consumer->secret = $_POST['reg_password'];
$this->consumer->ltiVersion = $_POST['lti_version'];
$this->consumer->name = $tcProfile->product_instance->service_owner->service_owner_name->default_value;
$this->consumer->consumerName = $this->consumer->name;
$this->consumer->consumerVersion = "{$tcProfile->product_instance->product_info->product_family->code}-{$tcProfile->product_instance->product_info->product_version}";
$this->consumer->consumerGuid = $tcProfile->product_instance->guid;
$this->consumer->enabled = true;
$this->consumer->protected = true;
$doSaveConsumer = true;
}
}
} else {
if ($this->ok && !empty($_POST['custom_tc_profile_url']) && empty($this->consumer->profile)) {
$http = new HTTPMessage($_POST['custom_tc_profile_url'], 'GET', null, 'Accept: application/vnd.ims.lti.v2.toolconsumerprofile+json');
if ($http->send()) {
$tcProfile = json_decode($http->response);
if (!is_null($tcProfile)) {
$this->consumer->profile = $tcProfile;
$doSaveConsumer = true;
}
}
}
}
// Validate message parameter constraints
if ($this->ok) {
$invalidParameters = array();
foreach ($this->constraints as $name => $constraint) {
if (empty($constraint['messages']) || in_array($_POST['lti_message_type'], $constraint['messages'])) {
$ok = true;
if ($constraint['required']) {
if (!isset($_POST[$name]) || strlen(trim($_POST[$name])) <= 0) {
$invalidParameters[] = "{$name} (missing)";
$ok = false;
}
}
if ($ok && !is_null($constraint['max_length']) && isset($_POST[$name])) {
if (strlen(trim($_POST[$name])) > $constraint['max_length']) {
$invalidParameters[] = "{$name} (too long)";
}
}
}
}
if (count($invalidParameters) > 0) {
$this->ok = false;
if (empty($this->reason)) {
$this->reason = 'Invalid parameter(s): ' . implode(', ', $invalidParameters) . '.';
}
}
}
if ($this->ok) {
// Set the request context
if (isset($_POST['context_id'])) {
$this->context = Context::fromConsumer($this->consumer, trim($_POST['context_id']));
$title = '';
if (isset($_POST['context_title'])) {
$title = trim($_POST['context_title']);
}
if (empty($title)) {
$title = "Course {$this->context->getId()}";
}
if (isset($_POST['context_type'])) {
$this->context->type = trim($_POST['context_type']);
}
$this->context->title = $title;
}
// Set the request resource link
if (isset($_POST['resource_link_id'])) {
$contentItemId = '';
if (isset($_POST['custom_content_item_id'])) {
$contentItemId = $_POST['custom_content_item_id'];
}
$this->resourceLink = ResourceLink::fromConsumer($this->consumer, trim($_POST['resource_link_id']), $contentItemId);
if (!empty($this->context)) {
$this->resourceLink->setContextId($this->context->getRecordId());
}
$title = '';
if (isset($_POST['resource_link_title'])) {
$title = trim($_POST['resource_link_title']);
}
if (empty($title)) {
$title = "Resource {$this->resourceLink->getId()}";
}
$this->resourceLink->title = $title;
// Delete any existing custom parameters
foreach ($this->consumer->getSettings() as $name => $value) {
if (strpos($name, 'custom_') === 0) {
$this->consumer->setSetting($name);
$doSaveConsumer = true;
}
}
if (!empty($this->context)) {
foreach ($this->context->getSettings() as $name => $value) {
if (strpos($name, 'custom_') === 0) {
$this->context->setSetting($name);
}
}
}
foreach ($this->resourceLink->getSettings() as $name => $value) {
if (strpos($name, 'custom_') === 0) {
$this->resourceLink->setSetting($name);
}
}
// Save LTI parameters
foreach (self::$LTI_CONSUMER_SETTING_NAMES as $name) {
if (isset($_POST[$name])) {
$this->consumer->setSetting($name, $_POST[$name]);
} else {
$this->consumer->setSetting($name);
}
}
if (!empty($this->context)) {
foreach (self::$LTI_CONTEXT_SETTING_NAMES as $name) {
if (isset($_POST[$name])) {
$this->context->setSetting($name, $_POST[$name]);
} else {
$this->context->setSetting($name);
}
}
}
foreach (self::$LTI_RESOURCE_LINK_SETTING_NAMES as $name) {
if (isset($_POST[$name])) {
$this->resourceLink->setSetting($name, $_POST[$name]);
} else {
$this->resourceLink->setSetting($name);
}
}
// Save other custom parameters
foreach ($_POST as $name => $value) {
if (strpos($name, 'custom_') === 0 && !in_array($name, array_merge(self::$LTI_CONSUMER_SETTING_NAMES, self::$LTI_CONTEXT_SETTING_NAMES, self::$LTI_RESOURCE_LINK_SETTING_NAMES))) {
$this->resourceLink->setSetting($name, $value);
}
}
}
// Set the user instance
$userId = '';
if (isset($_POST['user_id'])) {
$userId = trim($_POST['user_id']);
}
$this->user = User::fromResourceLink($this->resourceLink, $userId);
// Set the user name
$firstname = isset($_POST['lis_person_name_given']) ? $_POST['lis_person_name_given'] : '';
$lastname = isset($_POST['lis_person_name_family']) ? $_POST['lis_person_name_family'] : '';
$fullname = isset($_POST['lis_person_name_full']) ? $_POST['lis_person_name_full'] : '';
$this->user->setNames($firstname, $lastname, $fullname);
// Set the user email
$email = isset($_POST['lis_person_contact_email_primary']) ? $_POST['lis_person_contact_email_primary'] : '';
$this->user->setEmail($email, $this->defaultEmail);
// Set the user image URI
if (isset($_POST['user_image'])) {
$this->user->image = $_POST['user_image'];
}
// Set the user roles
if (isset($_POST['roles'])) {
$this->user->roles = self::parseRoles($_POST['roles']);
}
// Initialise the consumer and check for changes
$this->consumer->defaultEmail = $this->defaultEmail;
if ($this->consumer->ltiVersion !== $_POST['lti_version']) {
$this->consumer->ltiVersion = $_POST['lti_version'];
$doSaveConsumer = true;
}
if (isset($_POST['tool_consumer_instance_name'])) {
if ($this->consumer->consumerName !== $_POST['tool_consumer_instance_name']) {
$this->consumer->consumerName = $_POST['tool_consumer_instance_name'];
$doSaveConsumer = true;
}
}
if (isset($_POST['tool_consumer_info_product_family_code'])) {
$version = $_POST['tool_consumer_info_product_family_code'];
if (isset($_POST['tool_consumer_info_version'])) {
$version .= "-{$_POST['tool_consumer_info_version']}";
}
// do not delete any existing consumer version if none is passed
if ($this->consumer->consumerVersion !== $version) {
$this->consumer->consumerVersion = $version;
$doSaveConsumer = true;
}
} else {
if (isset($_POST['ext_lms']) && $this->consumer->consumerName !== $_POST['ext_lms']) {
$this->consumer->consumerVersion = $_POST['ext_lms'];
$doSaveConsumer = true;
}
}
if (isset($_POST['tool_consumer_instance_guid'])) {
if (is_null($this->consumer->consumerGuid)) {
$this->consumer->consumerGuid = $_POST['tool_consumer_instance_guid'];
$doSaveConsumer = true;
} else {
if (!$this->consumer->protected) {
$doSaveConsumer = $this->consumer->consumerGuid !== $_POST['tool_consumer_instance_guid'];
if ($doSaveConsumer) {
$this->consumer->consumerGuid = $_POST['tool_consumer_instance_guid'];
}
}
}
}
if (isset($_POST['launch_presentation_css_url'])) {
if ($this->consumer->cssPath !== $_POST['launch_presentation_css_url']) {
$this->consumer->cssPath = $_POST['launch_presentation_css_url'];
$doSaveConsumer = true;
}
} else {
if (isset($_POST['ext_launch_presentation_css_url']) && $this->consumer->cssPath !== $_POST['ext_launch_presentation_css_url']) {
$this->consumer->cssPath = $_POST['ext_launch_presentation_css_url'];
$doSaveConsumer = true;
} else {
if (!empty($this->consumer->cssPath)) {
$this->consumer->cssPath = null;
$doSaveConsumer = true;
}
}
}
}
// Persist changes to consumer
if ($doSaveConsumer) {
$this->consumer->save();
}
if ($this->ok && isset($this->context)) {
$this->context->save();
}
if ($this->ok && isset($this->resourceLink)) {
// Check if a share arrangement is in place for this resource link
$this->ok = $this->checkForShare();
// Persist changes to resource link
$this->resourceLink->save();
// Save the user instance
if (isset($_POST['lis_result_sourcedid'])) {
if ($this->user->ltiResultSourcedId !== $_POST['lis_result_sourcedid']) {
$this->user->ltiResultSourcedId = $_POST['lis_result_sourcedid'];
$this->user->save();
}
} else {
if (!empty($this->user->ltiResultSourcedId)) {
$this->user->ltiResultSourcedId = '';
$this->user->save();
}
}
}
return $this->ok;
}
/**
* Send a service request to the tool consumer.
*
* @param string $type Message type value
* @param string $url URL to send request to
* @param string $xml XML of message request
*
* @return boolean True if the request successfully obtained a response
*/
private function doLTI11Service($type, $url, $xml)
{
$ok = false;
$this->extRequest = null;
$this->extRequestHeaders = '';
$this->extResponse = null;
$this->extResponseHeaders = '';
if (!empty($url)) {
$id = uniqid();
$xmlRequest = <<<EOD
<?xml version = "1.0" encoding = "UTF-8"?>
<imsx_POXEnvelopeRequest xmlns = "http://www.imsglobal.org/services/ltiv1p1/xsd/imsoms_v1p0">
<imsx_POXHeader>
<imsx_POXRequestHeaderInfo>
<imsx_version>V1.0</imsx_version>
<imsx_messageIdentifier>{$id}</imsx_messageIdentifier>
</imsx_POXRequestHeaderInfo>
</imsx_POXHeader>
<imsx_POXBody>
<{$type}Request>
{$xml}
</{$type}Request>
</imsx_POXBody>
</imsx_POXEnvelopeRequest>
EOD;
// Calculate body hash
$hash = base64_encode(sha1($xmlRequest, true));
$params = array('oauth_body_hash' => $hash);
// Add OAuth signature
$hmacMethod = new OAuth\OAuthSignatureMethod_HMAC_SHA1();
$consumer = new OAuth\OAuthConsumer($this->getConsumer()->getKey(), $this->getConsumer()->secret, null);
$req = OAuth\OAuthRequest::from_consumer_and_token($consumer, null, 'POST', $url, $params);
$req->sign_request($hmacMethod, $consumer, null);
$params = $req->get_parameters();
$header = $req->to_header();
$header .= "\nContent-Type: application/xml";
// Connect to tool consumer
$http = new HTTPMessage($url, 'POST', $xmlRequest, $header);
// Parse XML response
if ($http->send()) {
$this->extResponse = $http->response;
$this->extResponseHeaders = $http->responseHeaders;
try {
$this->extDoc = new DOMDocument();
$this->extDoc->loadXML($http->response);
$this->extNodes = $this->domnodeToArray($this->extDoc->documentElement);
if (isset($this->extNodes['imsx_POXHeader']['imsx_POXResponseHeaderInfo']['imsx_statusInfo']['imsx_codeMajor']) && $this->extNodes['imsx_POXHeader']['imsx_POXResponseHeaderInfo']['imsx_statusInfo']['imsx_codeMajor'] === 'success') {
$ok = true;
}
} catch (\Exception $e) {
}
}
$this->extRequest = $http->request;
$this->extRequestHeaders = $http->requestHeaders;
}
return $ok;
}
/**
* Add the OAuth signature to an array of message parameters or to a header string.
*
* @return mixed Array of signed message parameters or header string
*/
public static function addSignature($endpoint, $consumerKey, $consumerSecret, $data, $method = 'POST', $type = null)
{
$params = array();
if (is_array($data)) {
$params = $data;
}
// Check for query parameters which need to be included in the signature
$queryParams = array();
$queryString = parse_url($endpoint, PHP_URL_QUERY);
if (!is_null($queryString)) {
$queryItems = explode('&', $queryString);
foreach ($queryItems as $item) {
if (strpos($item, '=') !== false) {
list($name, $value) = explode('=', $item);
$queryParams[urldecode($name)] = urldecode($value);
} else {
$queryParams[urldecode($item)] = '';
}
}
$params = $params + $queryParams;
}
if (!is_array($data)) {
// Calculate body hash
$hash = base64_encode(sha1($data, true));
$params['oauth_body_hash'] = $hash;
}
// Add OAuth signature
$hmacMethod = new OAuth\OAuthSignatureMethod_HMAC_SHA1();
$oauthConsumer = new OAuth\OAuthConsumer($consumerKey, $consumerSecret, null);
$oauthReq = OAuth\OAuthRequest::from_consumer_and_token($oauthConsumer, null, $method, $endpoint, $params);
$oauthReq->sign_request($hmacMethod, $oauthConsumer, null);
$params = $oauthReq->get_parameters();
// Remove parameters being passed on the query string
foreach (array_keys($queryParams) as $name) {
unset($params[$name]);
}
if (!is_array($data)) {
$header = $oauthReq->to_header();
if (empty($data)) {
if (!empty($type)) {
$header .= "\nAccept: {$type}";
}
} else {
if (isset($type)) {
$header .= "\nContent-Type: {$type}";
$header .= "\nContent-Length: " . strlen($data);
}
}
return $header;
} else {
return $params;
}
}
