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
26defined('MOODLE_INTERNAL') || die;
27
28require_once($CFG->dirroot.'/mod/lti/OAuthBody.php');
29require_once($CFG->dirroot.'/mod/lti/locallib.php');
30
31// TODO: Switch to core oauthlib once implemented - MDL-30149.
32use moodle\mod\lti as lti;
33
34define('LTI_ITEM_TYPE', 'mod');
35define('LTI_ITEM_MODULE', 'lti');
36define('LTI_SOURCE', 'mod/lti');
37
38function lti_get_response_xml($codemajor, $description, $messageref, $messagetype) {
39    $xml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><imsx_POXEnvelopeResponse />');
40    $xml->addAttribute('xmlns', 'http://www.imsglobal.org/services/ltiv1p1/xsd/imsoms_v1p0');
41
42    $headerinfo = $xml->addChild('imsx_POXHeader')->addChild('imsx_POXResponseHeaderInfo');
43
44    $headerinfo->addChild('imsx_version', 'V1.0');
45    $headerinfo->addChild('imsx_messageIdentifier', (string)mt_rand());
46
47    $statusinfo = $headerinfo->addChild('imsx_statusInfo');
48    $statusinfo->addchild('imsx_codeMajor', $codemajor);
49    $statusinfo->addChild('imsx_severity', 'status');
50    $statusinfo->addChild('imsx_description', $description);
51    $statusinfo->addChild('imsx_messageRefIdentifier', $messageref);
52    $incomingtype = str_replace('Response', 'Request', $messagetype);
53    $statusinfo->addChild('imsx_operationRefIdentifier', $incomingtype);
54
55    $xml->addChild('imsx_POXBody')->addChild($messagetype);
56
57    return $xml;
58}
59
60function lti_parse_message_id($xml) {
61    if (empty($xml->imsx_POXHeader)) {
62        return '';
63    }
64
65    $node = $xml->imsx_POXHeader->imsx_POXRequestHeaderInfo->imsx_messageIdentifier;
66    $messageid = (string)$node;
67
68    return $messageid;
69}
70
71function lti_parse_grade_replace_message($xml) {
72    $node = $xml->imsx_POXBody->replaceResultRequest->resultRecord->sourcedGUID->sourcedId;
73    $resultjson = json_decode((string)$node);
74    if ( is_null($resultjson) ) {
75        throw new Exception('Invalid sourcedId in result message');
76    }
77    $node = $xml->imsx_POXBody->replaceResultRequest->resultRecord->result->resultScore->textString;
78
79    $score = (string) $node;
80    if ( ! is_numeric($score) ) {
81        throw new Exception('Score must be numeric');
82    }
83    $grade = floatval($score);
84    if ( $grade < 0.0 || $grade > 1.0 ) {
85        throw new Exception('Score not between 0.0 and 1.0');
86    }
87
88    $parsed = new stdClass();
89    $parsed->gradeval = $grade;
90
91    $parsed->instanceid = $resultjson->data->instanceid;
92    $parsed->userid = $resultjson->data->userid;
93    $parsed->launchid = $resultjson->data->launchid;
94    $parsed->typeid = $resultjson->data->typeid;
95    $parsed->sourcedidhash = $resultjson->hash;
96
97    $parsed->messageid = lti_parse_message_id($xml);
98
99    return $parsed;
100}
101
102function lti_parse_grade_read_message($xml) {
103    $node = $xml->imsx_POXBody->readResultRequest->resultRecord->sourcedGUID->sourcedId;
104    $resultjson = json_decode((string)$node);
105    if ( is_null($resultjson) ) {
106        throw new Exception('Invalid sourcedId in result message');
107    }
108
109    $parsed = new stdClass();
110    $parsed->instanceid = $resultjson->data->instanceid;
111    $parsed->userid = $resultjson->data->userid;
112    $parsed->launchid = $resultjson->data->launchid;
113    $parsed->typeid = $resultjson->data->typeid;
114    $parsed->sourcedidhash = $resultjson->hash;
115
116    $parsed->messageid = lti_parse_message_id($xml);
117
118    return $parsed;
119}
120
121function lti_parse_grade_delete_message($xml) {
122    $node = $xml->imsx_POXBody->deleteResultRequest->resultRecord->sourcedGUID->sourcedId;
123    $resultjson = json_decode((string)$node);
124    if ( is_null($resultjson) ) {
125        throw new Exception('Invalid sourcedId in result message');
126    }
127
128    $parsed = new stdClass();
129    $parsed->instanceid = $resultjson->data->instanceid;
130    $parsed->userid = $resultjson->data->userid;
131    $parsed->launchid = $resultjson->data->launchid;
132    $parsed->typeid = $resultjson->data->typeid;
133    $parsed->sourcedidhash = $resultjson->hash;
134
135    $parsed->messageid = lti_parse_message_id($xml);
136
137    return $parsed;
138}
139
140function lti_accepts_grades($ltiinstance) {
141    global $DB;
142
143    $acceptsgrades = true;
144    $ltitype = $DB->get_record('lti_types', array('id' => $ltiinstance->typeid));
145
146    if (empty($ltitype->toolproxyid)) {
147        $typeconfig = lti_get_config($ltiinstance);
148
149        $typeacceptgrades = isset($typeconfig['acceptgrades']) ? $typeconfig['acceptgrades'] : LTI_SETTING_DELEGATE;
150
151        if (!($typeacceptgrades == LTI_SETTING_ALWAYS ||
152            ($typeacceptgrades == LTI_SETTING_DELEGATE && $ltiinstance->instructorchoiceacceptgrades == LTI_SETTING_ALWAYS))) {
153            $acceptsgrades = false;
154        }
155    } else {
156        $enabledcapabilities = explode("\n", $ltitype->enabledcapability);
157        $acceptsgrades = in_array('Result.autocreate', $enabledcapabilities) || in_array('BasicOutcome.url', $enabledcapabilities);
158    }
159
160    return $acceptsgrades;
161}
162
163/**
164 * Set the passed user ID to the session user.
165 *
166 * @param int $userid
167 */
168function lti_set_session_user($userid) {
169    global $DB;
170
171    if ($user = $DB->get_record('user', array('id' => $userid))) {
172        \core\session\manager::set_user($user);
173    }
174}
175
176function lti_update_grade($ltiinstance, $userid, $launchid, $gradeval) {
177    global $CFG, $DB;
178    require_once($CFG->libdir . '/gradelib.php');
179
180    $params = array();
181    $params['itemname'] = $ltiinstance->name;
182
183    $gradeval = $gradeval * floatval($ltiinstance->grade);
184
185    $grade = new stdClass();
186    $grade->userid   = $userid;
187    $grade->rawgrade = $gradeval;
188
189    $status = grade_update(LTI_SOURCE, $ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, 0, $grade, $params);
190
191    $record = $DB->get_record('lti_submission', array('ltiid' => $ltiinstance->id, 'userid' => $userid,
192        'launchid' => $launchid), 'id');
193    if ($record) {
194        $id = $record->id;
195    } else {
196        $id = null;
197    }
198
199    if (!empty($id)) {
200        $DB->update_record('lti_submission', array(
201            'id' => $id,
202            'dateupdated' => time(),
203            'gradepercent' => $gradeval,
204            'state' => 2
205        ));
206    } else {
207        $DB->insert_record('lti_submission', array(
208            'ltiid' => $ltiinstance->id,
209            'userid' => $userid,
210            'datesubmitted' => time(),
211            'dateupdated' => time(),
212            'gradepercent' => $gradeval,
213            'originalgrade' => $gradeval,
214            'launchid' => $launchid,
215            'state' => 1
216        ));
217    }
218
219    return $status == GRADE_UPDATE_OK;
220}
221
222function lti_read_grade($ltiinstance, $userid) {
223    global $CFG;
224    require_once($CFG->libdir . '/gradelib.php');
225
226    $grades = grade_get_grades($ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, $userid);
227
228    $ltigrade = floatval($ltiinstance->grade);
229
230    if (!empty($ltigrade) && isset($grades) && isset($grades->items[0]) && is_array($grades->items[0]->grades)) {
231        foreach ($grades->items[0]->grades as $agrade) {
232            $grade = $agrade->grade;
233            if (isset($grade)) {
234                return $grade / $ltigrade;
235            }
236        }
237    }
238}
239
240function lti_delete_grade($ltiinstance, $userid) {
241    global $CFG;
242    require_once($CFG->libdir . '/gradelib.php');
243
244    $grade = new stdClass();
245    $grade->userid   = $userid;
246    $grade->rawgrade = null;
247
248    $status = grade_update(LTI_SOURCE, $ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, 0, $grade);
249
250    return $status == GRADE_UPDATE_OK;
251}
252
253function lti_verify_message($key, $sharedsecrets, $body, $headers = null) {
254    foreach ($sharedsecrets as $secret) {
255        $signaturefailed = false;
256
257        try {
258            // TODO: Switch to core oauthlib once implemented - MDL-30149.
259            lti\handle_oauth_body_post($key, $secret, $body, $headers);
260        } catch (Exception $e) {
261            debugging('LTI message verification failed: '.$e->getMessage());
262            $signaturefailed = true;
263        }
264
265        if (!$signaturefailed) {
266            return $secret; // Return the secret used to sign the message).
267        }
268    }
269
270    return false;
271}
272
273/**
274 * Validate source ID from external request
275 *
276 * @param object $ltiinstance
277 * @param object $parsed
278 * @throws Exception
279 */
280function lti_verify_sourcedid($ltiinstance, $parsed) {
281    $sourceid = lti_build_sourcedid($parsed->instanceid, $parsed->userid,
282        $ltiinstance->servicesalt, $parsed->typeid, $parsed->launchid);
283
284    if ($sourceid->hash != $parsed->sourcedidhash) {
285        throw new Exception('SourcedId hash not valid');
286    }
287}
288
289/**
290 * Extend the LTI services through the ltisource plugins
291 *
292 * @param stdClass $data LTI request data
293 * @return bool
294 * @throws coding_exception
295 */
296function lti_extend_lti_services($data) {
297    $plugins = get_plugin_list_with_function('ltisource', $data->messagetype);
298    if (!empty($plugins)) {
299        // There can only be one.
300        if (count($plugins) > 1) {
301            throw new coding_exception('More than one ltisource plugin handler found');
302        }
303        $data->xml = new SimpleXMLElement($data->body);
304        $callback = current($plugins);
305        call_user_func($callback, $data);
306
307        return true;
308    }
309    return false;
310}
311