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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Utility code for LTI service handling.
  19   *
  20   * @package mod_lti
  21   * @copyright  Copyright (c) 2011 Moodlerooms Inc. (http://www.moodlerooms.com)
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   * @author     Chris Scribner
  24   */
  25  
  26  defined('MOODLE_INTERNAL') || die;
  27  
  28  require_once($CFG->dirroot.'/mod/lti/OAuthBody.php');
  29  
  30  // TODO: Switch to core oauthlib once implemented - MDL-30149.
  31  use moodle\mod\lti as lti;
  32  
  33  define('LTI_ITEM_TYPE', 'mod');
  34  define('LTI_ITEM_MODULE', 'lti');
  35  define('LTI_SOURCE', 'mod/lti');
  36  
  37  function lti_get_response_xml($codemajor, $description, $messageref, $messagetype) {
  38      $xml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><imsx_POXEnvelopeResponse />');
  39      $xml->addAttribute('xmlns', 'http://www.imsglobal.org/services/ltiv1p1/xsd/imsoms_v1p0');
  40  
  41      $headerinfo = $xml->addChild('imsx_POXHeader')->addChild('imsx_POXResponseHeaderInfo');
  42  
  43      $headerinfo->addChild('imsx_version', 'V1.0');
  44      $headerinfo->addChild('imsx_messageIdentifier', (string)mt_rand());
  45  
  46      $statusinfo = $headerinfo->addChild('imsx_statusInfo');
  47      $statusinfo->addchild('imsx_codeMajor', $codemajor);
  48      $statusinfo->addChild('imsx_severity', 'status');
  49      $statusinfo->addChild('imsx_description', $description);
  50      $statusinfo->addChild('imsx_messageRefIdentifier', $messageref);
  51      $incomingtype = str_replace('Response', 'Request', $messagetype);
  52      $statusinfo->addChild('imsx_operationRefIdentifier', $incomingtype);
  53  
  54      $xml->addChild('imsx_POXBody')->addChild($messagetype);
  55  
  56      return $xml;
  57  }
  58  
  59  function lti_parse_message_id($xml) {
  60      if (empty($xml->imsx_POXHeader)) {
  61          return '';
  62      }
  63  
  64      $node = $xml->imsx_POXHeader->imsx_POXRequestHeaderInfo->imsx_messageIdentifier;
  65      $messageid = (string)$node;
  66  
  67      return $messageid;
  68  }
  69  
  70  function lti_parse_grade_replace_message($xml) {
  71      $node = $xml->imsx_POXBody->replaceResultRequest->resultRecord->sourcedGUID->sourcedId;
  72      $resultjson = json_decode((string)$node);
  73  
  74      $node = $xml->imsx_POXBody->replaceResultRequest->resultRecord->result->resultScore->textString;
  75  
  76      $score = (string) $node;
  77      if ( ! is_numeric($score) ) {
  78          throw new Exception('Score must be numeric');
  79      }
  80      $grade = floatval($score);
  81      if ( $grade < 0.0 || $grade > 1.0 ) {
  82          throw new Exception('Score not between 0.0 and 1.0');
  83      }
  84  
  85      $parsed = new stdClass();
  86      $parsed->gradeval = $grade;
  87  
  88      $parsed->instanceid = $resultjson->data->instanceid;
  89      $parsed->userid = $resultjson->data->userid;
  90      $parsed->launchid = $resultjson->data->launchid;
  91      $parsed->typeid = $resultjson->data->typeid;
  92      $parsed->sourcedidhash = $resultjson->hash;
  93  
  94      $parsed->messageid = lti_parse_message_id($xml);
  95  
  96      return $parsed;
  97  }
  98  
  99  function lti_parse_grade_read_message($xml) {
 100      $node = $xml->imsx_POXBody->readResultRequest->resultRecord->sourcedGUID->sourcedId;
 101      $resultjson = json_decode((string)$node);
 102  
 103      $parsed = new stdClass();
 104      $parsed->instanceid = $resultjson->data->instanceid;
 105      $parsed->userid = $resultjson->data->userid;
 106      $parsed->launchid = $resultjson->data->launchid;
 107      $parsed->typeid = $resultjson->data->typeid;
 108      $parsed->sourcedidhash = $resultjson->hash;
 109  
 110      $parsed->messageid = lti_parse_message_id($xml);
 111  
 112      return $parsed;
 113  }
 114  
 115  function lti_parse_grade_delete_message($xml) {
 116      $node = $xml->imsx_POXBody->deleteResultRequest->resultRecord->sourcedGUID->sourcedId;
 117      $resultjson = json_decode((string)$node);
 118  
 119      $parsed = new stdClass();
 120      $parsed->instanceid = $resultjson->data->instanceid;
 121      $parsed->userid = $resultjson->data->userid;
 122      $parsed->launchid = $resultjson->data->launchid;
 123      $parsed->typeid = $resultjson->data->typeid;
 124      $parsed->sourcedidhash = $resultjson->hash;
 125  
 126      $parsed->messageid = lti_parse_message_id($xml);
 127  
 128      return $parsed;
 129  }
 130  
 131  function lti_accepts_grades($ltiinstance) {
 132      global $DB;
 133  
 134      $acceptsgrades = true;
 135      $ltitype = $DB->get_record('lti_types', array('id' => $ltiinstance->typeid));
 136  
 137      if (empty($ltitype->toolproxyid)) {
 138          $typeconfig = lti_get_config($ltiinstance);
 139  
 140          $typeacceptgrades = isset($typeconfig['acceptgrades']) ? $typeconfig['acceptgrades'] : LTI_SETTING_DELEGATE;
 141  
 142          if (!($typeacceptgrades == LTI_SETTING_ALWAYS ||
 143              ($typeacceptgrades == LTI_SETTING_DELEGATE && $ltiinstance->instructorchoiceacceptgrades == LTI_SETTING_ALWAYS))) {
 144              $acceptsgrades = false;
 145          }
 146      } else {
 147          $enabledcapabilities = explode("\n", $ltitype->enabledcapability);
 148          $acceptsgrades = in_array('Result.autocreate', $enabledcapabilities);
 149      }
 150  
 151      return $acceptsgrades;
 152  }
 153  
 154  /**
 155   * Set the passed user ID to the session user.
 156   *
 157   * @param int $userid
 158   */
 159  function lti_set_session_user($userid) {
 160      global $DB;
 161  
 162      if ($user = $DB->get_record('user', array('id' => $userid))) {
 163          \core\session\manager::set_user($user);
 164      }
 165  }
 166  
 167  function lti_update_grade($ltiinstance, $userid, $launchid, $gradeval) {
 168      global $CFG, $DB;
 169      require_once($CFG->libdir . '/gradelib.php');
 170  
 171      $params = array();
 172      $params['itemname'] = $ltiinstance->name;
 173  
 174      $gradeval = $gradeval * floatval($ltiinstance->grade);
 175  
 176      $grade = new stdClass();
 177      $grade->userid   = $userid;
 178      $grade->rawgrade = $gradeval;
 179  
 180      $status = grade_update(LTI_SOURCE, $ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, 0, $grade, $params);
 181  
 182      $record = $DB->get_record('lti_submission', array('ltiid' => $ltiinstance->id, 'userid' => $userid,
 183          'launchid' => $launchid), 'id');
 184      if ($record) {
 185          $id = $record->id;
 186      } else {
 187          $id = null;
 188      }
 189  
 190      if (!empty($id)) {
 191          $DB->update_record('lti_submission', array(
 192              'id' => $id,
 193              'dateupdated' => time(),
 194              'gradepercent' => $gradeval,
 195              'state' => 2
 196          ));
 197      } else {
 198          $DB->insert_record('lti_submission', array(
 199              'ltiid' => $ltiinstance->id,
 200              'userid' => $userid,
 201              'datesubmitted' => time(),
 202              'dateupdated' => time(),
 203              'gradepercent' => $gradeval,
 204              'originalgrade' => $gradeval,
 205              'launchid' => $launchid,
 206              'state' => 1
 207          ));
 208      }
 209  
 210      return $status == GRADE_UPDATE_OK;
 211  }
 212  
 213  function lti_read_grade($ltiinstance, $userid) {
 214      global $CFG;
 215      require_once($CFG->libdir . '/gradelib.php');
 216  
 217      $grades = grade_get_grades($ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, $userid);
 218  
 219      $ltigrade = floatval($ltiinstance->grade);
 220  
 221      if (!empty($ltigrade) && isset($grades) && isset($grades->items[0]) && is_array($grades->items[0]->grades)) {
 222          foreach ($grades->items[0]->grades as $agrade) {
 223              $grade = $agrade->grade;
 224              if (isset($grade)) {
 225                  return $grade / $ltigrade;
 226              }
 227          }
 228      }
 229  }
 230  
 231  function lti_delete_grade($ltiinstance, $userid) {
 232      global $CFG;
 233      require_once($CFG->libdir . '/gradelib.php');
 234  
 235      $grade = new stdClass();
 236      $grade->userid   = $userid;
 237      $grade->rawgrade = null;
 238  
 239      $status = grade_update(LTI_SOURCE, $ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, 0, $grade);
 240  
 241      return $status == GRADE_UPDATE_OK;
 242  }
 243  
 244  function lti_verify_message($key, $sharedsecrets, $body, $headers = null) {
 245      foreach ($sharedsecrets as $secret) {
 246          $signaturefailed = false;
 247  
 248          try {
 249              // TODO: Switch to core oauthlib once implemented - MDL-30149.
 250              lti\handle_oauth_body_post($key, $secret, $body, $headers);
 251          } catch (Exception $e) {
 252              $signaturefailed = true;
 253          }
 254  
 255          if (!$signaturefailed) {
 256              return $secret; // Return the secret used to sign the message).
 257          }
 258      }
 259  
 260      return false;
 261  }
 262  
 263  /**
 264   * Validate source ID from external request
 265   *
 266   * @param object $ltiinstance
 267   * @param object $parsed
 268   * @throws Exception
 269   */
 270  function lti_verify_sourcedid($ltiinstance, $parsed) {
 271      $sourceid = lti_build_sourcedid($parsed->instanceid, $parsed->userid,
 272          $ltiinstance->servicesalt, $parsed->typeid, $parsed->launchid);
 273  
 274      if ($sourceid->hash != $parsed->sourcedidhash) {
 275          throw new Exception('SourcedId hash not valid');
 276      }
 277  }
 278  
 279  /**
 280   * Extend the LTI services through the ltisource plugins
 281   *
 282   * @param stdClass $data LTI request data
 283   * @return bool
 284   * @throws coding_exception
 285   */
 286  function lti_extend_lti_services($data) {
 287      $plugins = get_plugin_list_with_function('ltisource', $data->messagetype);
 288      if (!empty($plugins)) {
 289          // There can only be one.
 290          if (count($plugins) > 1) {
 291              throw new coding_exception('More than one ltisource plugin handler found');
 292          }
 293          $data->xml = new SimpleXMLElement($data->body);
 294          $callback = current($plugins);
 295          call_user_func($callback, $data);
 296  
 297          return true;
 298      }
 299      return false;
 300  }