src/Util/LTI.php
public static function isRequestCheck($request_data=false) {
        if ( $request_data === false ) $request_data = $_REQUEST;
        if ( !isset($request_data["lti_message_type"]) ) return false;
        if ( !isset($request_data["lti_version"]) ) return false;
        $good_lti_version = self::isValidVersion($request_data["lti_version"]);
        if ( ! $good_lti_version ) return "Invalid LTI version ".$request_data["lti_version"];
        $good_message_type = self::isValidMessageType($request_data["lti_message_type"]);
        if ( ! $good_message_type ) return "Invalid message type ".$request_data["lti_message_type"];
        return true;
    }
public static function isRequestCheck($request_data=false) {
        if ( $request_data === false ) $request_data = $_REQUEST;
        if ( !isset($request_data["lti_message_type"]) ) return false;
        if ( !isset($request_data["lti_version"]) ) return false;
        $good_lti_version = self::isValidVersion($request_data["lti_version"]);
        if ( ! $good_lti_version ) return "Invalid LTI version ".$request_data["lti_version"];
        $good_message_type = self::isValidMessageType($request_data["lti_message_type"]);
        if ( ! $good_message_type ) return "Invalid message type ".$request_data["lti_message_type"];
        return true;
    }
public static function isRequestCheck ( $ request_data = false ) { if ( $ request_data === false ) $ request_data = $ _REQUEST ; if ( ! isset ( $ request_data [ "lti_message_type" ] ) ) return false ; if ( ! isset ( $ request_data [ "lti_version" ] ) ) return false ; $ good_lti_version = self :: isValidVersion ( $ request_data [ "lti_version" ] ) ; if ( ! $ good_lti_version ) return "Invalid LTI version " . $ request_data [ "lti_version" ] ; $ good_message_type = self :: isValidMessageType ( $ request_data [ "lti_message_type" ] ) ; if ( ! $ good_message_type ) return "Invalid message type " . $ request_data [ "lti_message_type" ] ; return true ; }
Determines if this is a valid Basic LTI message

@retval mixed Returns true if this is a Basic LTI message
with minimum values to meet the protocol.  Returns false
if this is not even close to an LTI launch.  If this is a
broken launch, it returns an error as to why.
Determines if this is a valid Basic LTI message