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/>.

/**

 * Manager class for antivirus integration.

 *

 * @package    core_antivirus

 * @copyright  2015 Ruslan Kabalin, Lancaster University.

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

 */

namespace core\antivirus;

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

/**

 * Class used for various antivirus related stuff.

 *

 * @package    core_antivirus

 * @copyright  2015 Ruslan Kabalin, Lancaster University.

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

 */

class manager {

    /**

     * Returns list of enabled antiviruses.

     *

     * @return array Array ('antivirusname'=>stdClass antivirus object).

     */

    private static function get_enabled() {

        global $CFG;

        $active = array();

        if (empty($CFG->antiviruses)) {

            return $active;

        }

        foreach (explode(',', $CFG->antiviruses) as $e) {

            if ($antivirus = self::get_antivirus($e)) {

                if ($antivirus->is_configured()) {

                    $active[$e] = $antivirus;

                }

            }

        }

        return $active;

    }

    /**

     * Scan file using all enabled antiviruses, throws exception in case of infected file.

     *

     * @param string $file Full path to the file.

     * @param string $filename Name of the file (could be different from physical file if temp file is used).

     * @param bool $deleteinfected whether infected file needs to be deleted.

     * @throws \core\antivirus\scanner_exception If file is infected.

     * @return void

     */

    public static function scan_file($file, $filename, $deleteinfected) {

        global $USER;

        $antiviruses = self::get_enabled();

        $notifylevel = (int)get_config('antivirus', 'notifylevel');

        foreach ($antiviruses as $antivirus) {

            // Attempt to scan, catching internal exceptions.

            try {

                $result = $antivirus->scan_file($file, $filename);

            } catch (\core\antivirus\scanner_exception $e) {

                $notice = $antivirus->get_scanning_notice();

                $incidentdetails = $antivirus->get_incident_details($file, $filename, $notice, false);

                // Log scan error event.

                $params = [

                    'context' => \context_system::instance(),

                    'relateduserid' => $USER->id,

                    'other' => ['filename' => $filename, 'incidentdetails' => $incidentdetails],

                ];

                $event = \core\event\antivirus_scan_file_error::create($params);

                $event->trigger();

                // If there was a scanner exception (such as ClamAV denying

                // upload), send messages (on error and above), and rethrow.

                if ($notifylevel === $antivirus::SCAN_RESULT_ERROR) {

                    $notice = $antivirus->get_scanning_notice();

                    self::send_antivirus_messages($antivirus, $incidentdetails);

                }

                throw $e;

            }

            $notice = $antivirus->get_scanning_notice();

            if ($result === $antivirus::SCAN_RESULT_FOUND) {

                // Infection found, send notification.

                $incidentdetails = $antivirus->get_incident_details($file, $filename, $notice);

                self::send_antivirus_messages($antivirus, $incidentdetails);

                // Move to quarantine folder.

                $zipfile = \core\antivirus\quarantine::quarantine_file($file, $filename, $incidentdetails, $notice);

                // If file not stored due to disabled quarantine, store a message.

                if (empty($zipfile)) {

                    $zipfile = get_string('quarantinedisabled', 'antivirus');

                }

                // Log file infected event.

                $params = [

                    'context' => \context_system::instance(),

                    'relateduserid' => $USER->id,

                    'other' => ['filename' => $filename, 'zipfile' => $zipfile, 'incidentdetails' => $incidentdetails],

                ];

                $event = \core\event\virus_infected_file_detected::create($params);

                $event->trigger();

                if ($deleteinfected) {

                    unlink($file);

                }

                // Get custom message to display to user from antivirus engine.

                $displaymessage = $antivirus->get_virus_found_message();

                $placeholders = array_merge(['item' => $filename], $displaymessage['placeholders']);

                throw new \core\antivirus\scanner_exception(

                    $displaymessage['string'],

                    '',

                    $placeholders,

                    null,

                    $displaymessage['component']

                );

            } else if ($result === $antivirus::SCAN_RESULT_ERROR) {

                // Here we need to generate a different incident based on an error.

                $incidentdetails = $antivirus->get_incident_details($file, $filename, $notice, false);

                // Log scan error event.

                $params = [

                    'context' => \context_system::instance(),

                    'relateduserid' => $USER->id,

                    'other' => ['filename' => $filename, 'incidentdetails' => $incidentdetails],

                ];

                $event = \core\event\antivirus_scan_file_error::create($params);

                $event->trigger();

                // Send a notification if required (error or above).

                if ($notifylevel === $antivirus::SCAN_RESULT_ERROR) {

                    self::send_antivirus_messages($antivirus, $incidentdetails);

                }

            }

        }

    }

    /**

     * Scan data steam using all enabled antiviruses, throws exception in case of infected data.

     *

     * @param string $data The variable containing the data to scan.

     * @throws \core\antivirus\scanner_exception If data is infected.

     * @return void

     */

    public static function scan_data($data) {

        global $USER;

        $antiviruses = self::get_enabled();

        $notifylevel = (int)get_config('antivirus', 'notifylevel');

        foreach ($antiviruses as $antivirus) {

            // Attempt to scan, catching internal exceptions.

            try {

                $result = $antivirus->scan_data($data);

            } catch (\core\antivirus\scanner_exception $e) {

                $notice = $antivirus->get_scanning_notice();

                $incidentdetails = $antivirus->get_incident_details('', $filename, $notice, false);

                // Log scan error event.

                $params = [

                    'context' => \context_system::instance(),

                    'relateduserid' => $USER->id,

                    'other' => ['filename' => $filename, 'incidentdetails' => $incidentdetails],

                ];

                $event = \core\event\antivirus_scan_file_error::create($params);

                $event->trigger();

                // If there was a scanner exception (such as ClamAV denying upload), send messages and rethrow.

                if ($notifylevel === $antivirus::SCAN_RESULT_ERROR) {

                    $notice = $antivirus->get_scanning_notice();

                    $filename = get_string('datastream', 'antivirus');

                    self::send_antivirus_messages($antivirus, $incidentdetails);

                }

                throw $e;

            }

            $filename = get_string('datastream', 'antivirus');

            $notice = $antivirus->get_scanning_notice();

            if ($result === $antivirus::SCAN_RESULT_FOUND) {

                // Infection found, send notification.

                $incidentdetails = $antivirus->get_incident_details('', $filename, $notice);

                self::send_antivirus_messages($antivirus, $incidentdetails);

                // Copy data to quarantine folder.

                $zipfile = \core\antivirus\quarantine::quarantine_data($data, $filename, $incidentdetails, $notice);

                // If file not stored due to disabled quarantine, store a message.

                if (empty($zipfile)) {

                    $zipfile = get_string('quarantinedisabled', 'antivirus');

                }

                // Log file infected event.

                $params = [

                    'context' => \context_system::instance(),

                    'relateduserid' => $USER->id,

                    'other' => ['filename' => $filename, 'zipfile' => $zipfile, 'incidentdetails' => $incidentdetails],

                ];

                $event = \core\event\virus_infected_data_detected::create($params);

                $event->trigger();

                // Get custom message to display to user from antivirus engine.

                $displaymessage = $antivirus->get_virus_found_message();

                $placeholders = array_merge(['item' => get_string('datastream', 'antivirus')], $displaymessage['placeholders']);

                throw new \core\antivirus\scanner_exception(

                    $displaymessage['string'],

                    '',

                    $placeholders,

                    null,

                    $displaymessage['component']

                );

            } else if ($result === $antivirus::SCAN_RESULT_ERROR) {

                // Here we need to generate a different incident based on an error.

                $incidentdetails = $antivirus->get_incident_details('', $filename, $notice, false);

                // Log scan error event.

                $params = [

                    'context' => \context_system::instance(),

                    'relateduserid' => $USER->id,

                    'other' => ['filename' => $filename, 'incidentdetails' => $incidentdetails],

                ];

                $event = \core\event\antivirus_scan_data_error::create($params);

                $event->trigger();

                // Send a notification if required (error or above).

                if ($notifylevel === $antivirus::SCAN_RESULT_ERROR) {

                    self::send_antivirus_messages($antivirus, $incidentdetails);

                }

            }

        }

    }

    /**

     * Returns instance of antivirus.

     *

     * @param string $antivirusname name of antivirus.

     * @return object|bool antivirus instance or false if does not exist.

     */

    public static function get_antivirus($antivirusname) {

        global $CFG;

        $classname = '\\antivirus_' . $antivirusname . '\\scanner';

        if (!class_exists($classname)) {

            return false;

        }

        return new $classname();

    }

    /**

     * Get the list of available antiviruses.

     *

     * @return array Array ('antivirusname'=>'localised antivirus name').

     */

    public static function get_available() {

        $antiviruses = array();

        foreach (\core_component::get_plugin_list('antivirus') as $antivirusname => $dir) {

            $antiviruses[$antivirusname] = get_string('pluginname', 'antivirus_'.$antivirusname);

        }

        return $antiviruses;

    }

    /**

     * This function puts all relevant information into the messages required, and sends them.

     *

     * @param \core\antivirus\scanner $antivirus the scanner engine.

     * @param string $incidentdetails details of the incident.

     * @return void

     */

    public static function send_antivirus_messages(\core\antivirus\scanner $antivirus, string $incidentdetails) {

        $messages = $antivirus->get_messages();

        // If there is no messages, and a virus is found, we should generate one, then send it.

        if (empty($messages)) {

            $antivirus->message_admins($antivirus->get_scanning_notice(), FORMAT_MOODLE, 'infected');

            $messages = $antivirus->get_messages();

        }

        foreach ($messages as $message) {

            // Check if the information is already in the current scanning notice.

            if (!empty($antivirus->get_scanning_notice()) &&

                strpos($antivirus->get_scanning_notice(), $message->fullmessage) === false) {

                // This is some extra information. We should append this to the end of the incident details.

                $incidentdetails .= \html_writer::tag('pre', $message->fullmessage);

            }

            // Now update the message to the detailed version, and format.

            $message->name = 'infected';

            $message->fullmessagehtml = $incidentdetails;

            $message->fullmessageformat = FORMAT_MOODLE;

            $message->fullmessage = format_text_email($incidentdetails, $message->fullmessageformat);

            // Now we must check if message is going to a real account.

            // It may be an email that needs to be sent to non-user address.

            if ($message->userto->id === -1) {

                // If this doesnt exist, send a regular email.

                email_to_user(

                    $message->userto,

                    get_admin(),

                    $message->subject,

                    $message->fullmessage,

                    $message->fullmessagehtml

                );

            } else {

                // And now we can send.

                message_send($message);

            }

        }

    }

}