Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * Entity model representing quiz settings for the seb plugin.

 *

 * @package    quizaccess_seb

 * @author     Andrew Madden <andrewmadden@catalyst-au.net>

 * @copyright  2019 Catalyst IT

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

namespace quizaccess_seb;

use CFPropertyList\CFArray;

use CFPropertyList\CFBoolean;

use CFPropertyList\CFDictionary;

use CFPropertyList\CFNumber;

use CFPropertyList\CFString;

use core\persistent;

use lang_string;

use moodle_exception;

use moodle_url;

defined('MOODLE_INTERNAL') || die();

/**

 * Entity model representing quiz settings for the seb plugin.

 *

 * @copyright  2020 Catalyst IT

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class seb_quiz_settings extends persistent {

    /** Table name for the persistent. */

    const TABLE = 'quizaccess_seb_quizsettings';

    /** @var property_list $plist The SEB config represented as a Property List object. */

    private $plist;

    /** @var string $config The SEB config represented as a string. */

    private $config;

    /** @var string $configkey The SEB config key represented as a string. */

    private $configkey;

    /**

     * Return the definition of the properties of this model.

     *

     * @return array

     */

    protected static function define_properties(): array {

        return [

            'quizid' => [

                'type' => PARAM_INT,

            ],

            'cmid' => [

                'type' => PARAM_INT,

            ],

            'templateid' => [

                'type' => PARAM_INT,

                'default' => 0,

            ],

            'requiresafeexambrowser' => [

                'type' => PARAM_INT,

                'default' => 0,

            ],

            'showsebtaskbar' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'showwificontrol' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'showreloadbutton' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'showtime' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'showkeyboardlayout' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'allowuserquitseb' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'quitpassword' => [

                'type' => PARAM_TEXT,

                'default' => '',

                'null' => NULL_ALLOWED,

            ],

            'linkquitseb' => [

                'type' => PARAM_URL,

                'default' => '',

                'null' => NULL_ALLOWED,

            ],

            'userconfirmquit' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'enableaudiocontrol' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'muteonstartup' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'allowcapturecamera' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'allowcapturemicrophone' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'allowspellchecking' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'allowreloadinexam' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'activateurlfiltering' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'filterembeddedcontent' => [

                'type' => PARAM_INT,

                'default' => 0,

                'null' => NULL_ALLOWED,

            ],

            'expressionsallowed' => [

                'type' => PARAM_TEXT,

                'default' => '',

                'null' => NULL_ALLOWED,

            ],

            'regexallowed' => [

                'type' => PARAM_TEXT,

                'default' => '',

                'null' => NULL_ALLOWED,

            ],

            'expressionsblocked' => [

                'type' => PARAM_TEXT,

                'default' => '',

                'null' => NULL_ALLOWED,

            ],

            'regexblocked' => [

                'type' => PARAM_TEXT,

                'default' => '',

                'null' => NULL_ALLOWED,

            ],

            'showsebdownloadlink' => [

                'type' => PARAM_INT,

                'default' => 1,

                'null' => NULL_ALLOWED,

            ],

            'allowedbrowserexamkeys' => [

                'type' => PARAM_TEXT,

                'default' => '',

                'null' => NULL_ALLOWED,

            ],

        ];

    }

    /**

     * Return an instance by quiz id.

     *

     * This method gets data from cache before doing any DB calls.

     *

     * @param int $quizid Quiz id.

     * @return false|\quizaccess_seb\seb_quiz_settings

     */

    public static function get_by_quiz_id(int $quizid) {

        if ($data = self::get_quiz_settings_cache()->get($quizid)) {

            return new static(0, $data);

        }

        return self::get_record(['quizid' => $quizid]);

    }

    /**

     * Return cached SEB config represented as a string by quiz ID.

     *

     * @param int $quizid Quiz id.

     * @return string|null

     */

    public static function get_config_by_quiz_id(int $quizid): ?string {

        $config = self::get_config_cache()->get($quizid);

        if ($config !== false) {

            return $config;

        }

        $config = null;

        if ($settings = self::get_by_quiz_id($quizid)) {

            $config = $settings->get_config();

            self::get_config_cache()->set($quizid, $config);

        }

        return $config;

    }

    /**

     * Return cached SEB config key by quiz ID.

     *

     * @param int $quizid Quiz id.

     * @return string|null

     */

    public static function get_config_key_by_quiz_id(int $quizid): ?string {

        $configkey = self::get_config_key_cache()->get($quizid);

        if ($configkey !== false) {

            return $configkey;

        }

        $configkey = null;

        if ($settings = self::get_by_quiz_id($quizid)) {

            $configkey = $settings->get_config_key();

            self::get_config_key_cache()->set($quizid, $configkey);

        }

        return $configkey;

    }

    /**

     * Return SEB config key cache instance.

     *

     * @return \cache_application

     */

    private static function get_config_key_cache(): \cache_application {

        return \cache::make('quizaccess_seb', 'configkey');

    }

    /**

     * Return SEB config cache instance.

     *

     * @return \cache_application

     */

    private static function get_config_cache(): \cache_application {

        return \cache::make('quizaccess_seb', 'config');

    }

    /**

     * Return quiz settings cache object,

     *

     * @return \cache_application

     */

    private static function get_quiz_settings_cache(): \cache_application {

        return \cache::make('quizaccess_seb', 'quizsettings');

    }

    /**

     * Adds the new record to the cache.

     */

    protected function after_create() {

        $this->after_save();

    }

    /**

     * Updates the cache record.

     *

     * @param bool $result

     */

    protected function after_update($result) {

        $this->after_save();

    }

    /**

     * Helper method to execute common stuff after create and update.

     */

    private function after_save() {

        self::get_quiz_settings_cache()->set($this->get('quizid'), $this->to_record());

        self::get_config_cache()->set($this->get('quizid'), $this->config);

        self::get_config_key_cache()->set($this->get('quizid'), $this->configkey);

    }

    /**

     * Removes unnecessary stuff from db.

     */

    protected function before_delete() {

        $key = $this->get('quizid');

        self::get_quiz_settings_cache()->delete($key);

        self::get_config_cache()->delete($key);

        self::get_config_key_cache()->delete($key);

    }

    /**

     * Validate the browser exam keys string.

     *

     * @param string $keys Newline separated browser exam keys.

     * @return true|lang_string If there is an error, an error string is returned.

     */

    protected function validate_allowedbrowserexamkeys($keys) {

        $keys = $this->split_keys($keys);

        foreach ($keys as $i => $key) {

            if (!preg_match('~^[a-f0-9]{64}$~', $key)) {

                return new lang_string('allowedbrowserkeyssyntax', 'quizaccess_seb');

            }

        }

        if (count($keys) != count(array_unique($keys))) {

            return new lang_string('allowedbrowserkeysdistinct', 'quizaccess_seb');

        }

        return true;

    }

    /**

     * Get the browser exam keys as a pre-split array instead of just as a string.

     *

     * @return array

     */

    protected function get_allowedbrowserexamkeys(): array {

        $keysstring = $this->raw_get('allowedbrowserexamkeys');

        $keysstring = empty($keysstring) ? '' : $keysstring;

        return $this->split_keys($keysstring);

    }

    /**

     * Hook to execute before an update.

     *

     * Please note that at this stage the data has already been validated and therefore

     * any new data being set will not be validated before it is sent to the database.

     */

    protected function before_update() {

        $this->before_save();

    }

    /**

     * Hook to execute before a create.

     *

     * Please note that at this stage the data has already been validated and therefore

     * any new data being set will not be validated before it is sent to the database.

     */

    protected function before_create() {

        $this->before_save();

    }

    /**

     * As there is no hook for before both create and update, this function is called by both hooks.

     */

    private function before_save() {

        // Set template to 0 if using anything different to template.

        if ($this->get('requiresafeexambrowser') != settings_provider::USE_SEB_TEMPLATE) {

            $this->set('templateid', 0);

        }

        // Process configs to make sure that all data is set correctly.

        $this->process_configs();

    }

    /**

     * Before validate hook.

     */

    protected function before_validate() {

        // Template can't be null.

        if (is_null($this->raw_get('templateid'))) {

            $this->set('templateid', 0);

        }

    }

    /**

     * Create or update the config string based on the current quiz settings.

     */

    private function process_configs() {

        switch ($this->get('requiresafeexambrowser')) {

            case settings_provider::USE_SEB_NO:

                $this->process_seb_config_no();

                break;

            case settings_provider::USE_SEB_CONFIG_MANUALLY:

                $this->process_seb_config_manually();

                break;

            case settings_provider::USE_SEB_TEMPLATE:

                $this->process_seb_template();

                break;

            case settings_provider::USE_SEB_UPLOAD_CONFIG:

                $this->process_seb_upload_config();

                break;

            default: // Also settings_provider::USE_SEB_CLIENT_CONFIG.

                $this->process_seb_client_config();

        }

        // Generate config key based on given SEB config.

        if (!empty($this->config)) {

            $this->configkey = config_key::generate($this->config)->get_hash();

        } else {

            $this->configkey = null;

        }

    }

    /**

     * Return SEB config key.

     *

     * @return string|null

     */

    public function get_config_key(): ?string {

        $this->process_configs();

        return $this->configkey;

    }

    /**

     * Return string representation of the config.

     *

     * @return string|null

     */

    public function get_config(): ?string {

        $this->process_configs();

        return $this->config;

    }

    /**

     * Case for USE_SEB_NO.

     */

    private function process_seb_config_no() {

        $this->config = null;

    }

    /**

     * Case for USE_SEB_CONFIG_MANUALLY. This creates a plist and applies all settings from the posted form, along with

     * some defaults.

     */

    private function process_seb_config_manually() {

        // If at any point a configuration file has been uploaded and parsed, clear the settings.

        $this->plist = new property_list();

        $this->process_bool_settings();

        $this->process_quit_password_settings();

        $this->process_quit_url_from_settings();

        $this->process_url_filters();

        $this->process_required_enforced_settings();

        // One of the requirements for USE_SEB_CONFIG_MANUALLY is setting examSessionClearCookiesOnStart to false.

        $this->plist->set_or_update_value('examSessionClearCookiesOnStart', new CFBoolean(false));

        $this->plist->set_or_update_value('allowPreferencesWindow', new CFBoolean(false));

        $this->config = $this->plist->to_xml();

    }

    /**

     * Case for USE_SEB_TEMPLATE. This creates a plist from the template uploaded, then applies the quit password

     * setting and some defaults.

     */

    private function process_seb_template() {

        $template = template::get_record(['id' => $this->get('templateid')]);

        $this->plist = new property_list($template->get('content'));

        $this->process_bool_setting('allowuserquitseb');

        $this->process_quit_password_settings();

        $this->process_quit_url_from_template_or_config();

        $this->process_required_enforced_settings();

        $this->config = $this->plist->to_xml();

    }

    /**

     * Case for USE_SEB_UPLOAD_CONFIG. This creates a plist from an uploaded configuration file, then applies the quiz

     * password settings and some defaults.

     */

    private function process_seb_upload_config() {

        $file = settings_provider::get_module_context_sebconfig_file($this->get('cmid'));

        // If there was no file, create an empty plist so the rest of this wont explode.

        if (empty($file)) {

            throw new moodle_exception('noconfigfilefound', 'quizaccess_seb', '', $this->get('cmid'));

        } else {

            $this->plist = new property_list($file->get_content());

        }

        $this->process_quit_url_from_template_or_config();

        $this->process_required_enforced_settings();

        $this->config = $this->plist->to_xml();

    }

    /**

     * Case for USE_SEB_CLIENT_CONFIG. This creates an empty plist to remove the config stored.

     */

    private function process_seb_client_config() {

        $this->config = null;

    }

    /**

     * Sets or updates some sensible default settings, these are the items 'startURL' and 'sendBrowserExamKey'.

     */

    private function process_required_enforced_settings() {

        global $CFG;

        $quizurl = new moodle_url($CFG->wwwroot . "/mod/quiz/view.php", ['id' => $this->get('cmid')]);

        $this->plist->set_or_update_value('startURL', new CFString($quizurl->out(true)));

        $this->plist->set_or_update_value('sendBrowserExamKey', new CFBoolean(true));

        // Use the modern WebView and JS API if the SEB version supports it.

        // Documentation: https://safeexambrowser.org/developer/seb-config-key.html .

        // "Set the key browserWindowWebView to the policy "Prefer Modern" (value 3)".

        $this->plist->set_or_update_value('browserWindowWebView', new CFNumber(3));

    }

    /**

     * Use the boolean map to add Moodle boolean setting to config PList.

     */

    private function process_bool_settings() {

        $settings = $this->to_record();

        $map = $this->get_bool_seb_setting_map();

        foreach ($settings as $setting => $value) {

            if (isset($map[$setting])) {

                $this->process_bool_setting($setting);

            }

        }

    }

    /**

     * Process provided single bool setting.

     *

     * @param string $name Setting name matching one from self::get_bool_seb_setting_map.

     */

    private function process_bool_setting(string $name) {

        $map = $this->get_bool_seb_setting_map();

        if (!isset($map[$name])) {

            throw new \coding_exception('Provided setting name can not be found in known bool settings');

        }

        $enabled = $this->raw_get($name) == 1 ? true : false;

        $this->plist->set_or_update_value($map[$name], new CFBoolean($enabled));

    }

    /**

     * Turn hashed quit password and quit link into PList strings and add to config PList.

     */

    private function process_quit_password_settings() {

        $settings = $this->to_record();

        if (!empty($settings->quitpassword) && is_string($settings->quitpassword)) {

            // Hash quit password.

            $hashedpassword = hash('SHA256', $settings->quitpassword);

            $this->plist->add_element_to_root('hashedQuitPassword', new CFString($hashedpassword));

        } else if (!is_null($this->plist->get_element_value('hashedQuitPassword'))) {

            $this->plist->delete_element('hashedQuitPassword');

        }

    }

    /**

     * Sets the quitURL if found in the seb_quiz_settings.

     */

    private function process_quit_url_from_settings() {

        $settings = $this->to_record();

        if (!empty($settings->linkquitseb) && is_string($settings->linkquitseb)) {

            $this->plist->set_or_update_value('quitURL', new CFString($settings->linkquitseb));

        }

    }

    /**

     * Sets the quiz_setting's linkquitseb if a quitURL value was found in a template or uploaded config.

     */

    private function process_quit_url_from_template_or_config() {

        // Does the plist (template or config file) have an existing quitURL?

        $quiturl = $this->plist->get_element_value('quitURL');

        if (!empty($quiturl)) {

            $this->set('linkquitseb', $quiturl);

        }

    }

    /**

     * Turn return separated strings for URL filters into a PList array and add to config PList.

     */

    private function process_url_filters() {

        $settings = $this->to_record();

        // Create rules to each expression provided and add to config.

        $urlfilterrules = [];

        // Get all rules separated by newlines and remove empty rules.

        $expallowed = array_filter(explode(PHP_EOL, $settings->expressionsallowed));

        $expblocked = array_filter(explode(PHP_EOL, $settings->expressionsblocked));

        $regallowed = array_filter(explode(PHP_EOL, $settings->regexallowed));

        $regblocked = array_filter(explode(PHP_EOL, $settings->regexblocked));

        foreach ($expallowed as $rulestring) {

            $urlfilterrules[] = $this->create_filter_rule($rulestring, true, false);

        }

        foreach ($expblocked as $rulestring) {

            $urlfilterrules[] = $this->create_filter_rule($rulestring, false, false);

        }

        foreach ($regallowed as $rulestring) {

            $urlfilterrules[] = $this->create_filter_rule($rulestring, true, true);

        }

        foreach ($regblocked as $rulestring) {

            $urlfilterrules[] = $this->create_filter_rule($rulestring, false, true);

        }

        $this->plist->add_element_to_root('URLFilterRules', new CFArray($urlfilterrules));

    }

    /**

     * Create a CFDictionary represeting a URL filter rule.

     *

     * @param string $rulestring The expression to filter with.

     * @param bool $allowed Allowed or blocked.

     * @param bool $isregex Regex or simple.

     * @return CFDictionary A PList dictionary.

     */

    private function create_filter_rule(string $rulestring, bool $allowed, bool $isregex): CFDictionary {

        $action = $allowed ? 1 : 0;

        return new CFDictionary([

                    'action' => new CFNumber($action),

                    'active' => new CFBoolean(true),

                    'expression' => new CFString(trim($rulestring)),

                    'regex' => new CFBoolean($isregex),

                    ]);

    }

    /**

     * Map the settings that are booleans to the Safe Exam Browser config keys.

     *

     * @return array Moodle setting as key, SEB setting as value.

     */

    private function get_bool_seb_setting_map(): array {

        return [

            'activateurlfiltering' => 'URLFilterEnable',

            'allowspellchecking' => 'allowSpellCheck',

            'allowreloadinexam' => 'browserWindowAllowReload',

            'allowuserquitseb' => 'allowQuit',

            'enableaudiocontrol' => 'audioControlEnabled',

            'allowcapturecamera' => 'browserMediaCaptureCamera',

            'allowcapturemicrophone' => 'browserMediaCaptureMicrophone',

            'filterembeddedcontent' => 'URLFilterEnableContentFilter',

            'muteonstartup' => 'audioMute',

            'showkeyboardlayout' => 'showInputLanguage',

            'showreloadbutton' => 'showReloadButton',

            'showsebtaskbar' => 'showTaskBar',

            'showtime' => 'showTime',

            'showwificontrol' => 'allowWlan',

            'userconfirmquit' => 'quitURLConfirm',

        ];

    }

    /**

     * This helper method takes list of browser exam keys in a string and splits it into an array of separate keys.

     *

     * @param string|null $keys the allowed keys.

     * @return array of string, the separate keys.

     */

    private function split_keys($keys): array {

        $keys = preg_split('~[ \t\n\r,;]+~', $keys ?? '', -1, PREG_SPLIT_NO_EMPTY);

        foreach ($keys as $i => $key) {

            $keys[$i] = strtolower($key);

        }

        return $keys;

    }

}