Merge branch 'auto_update'

README.md

@@ -11,7 +11,7 @@ This repository contains the core of Mibew Messenger application.
 ## Server requirements
 
 1. A webserver or web hosting account running on any major Operating System
-2. PHP (5.3.3 and above) with PDO, pdo_mysql and gd extensions
+2. PHP (5.3.3 and above) with PDO, pdo_mysql, cURL and gd extensions
 3. MySQL 5.0 and above
 
 ## Build from sources

src/mibew/README.txt

@@ -6,7 +6,7 @@ REQUIREMENTS
  * Apache web server 1.3.34 or above with the ability to use local .htaccess
    files (mod_rewrite module is optional, but recommended)
  * MySQL database 5.0 or above
- * PHP 5.3.3 or above with PDO, pdo_mysql and gd extensions
+ * PHP 5.3.3 or above with PDO, pdo_mysql, cURL and gd extensions
 
 INSTALLATION
 

src/mibew/configs/database_schema.yml

@@ -316,3 +316,19 @@ plugin:
         enabled: "tinyint NOT NULL DEFAULT 0"
     unique_keys:
         name: [name]
+
+# Contains info about all available updates
+availableupdate:
+    fields:
+        # Artificial ID
+        id: "INT NOT NULL auto_increment PRIMARY KEY"
+        # Can be either "core" or fully qualified plugin's name
+        target: "varchar(255) NOT NULL"
+        # The latest available version of the plugin
+        version: "varchar(255) NOT NULL"
+        # A URL where the new version can be downloaded
+        url: "text"
+        # Description of the update
+        description: "text"
+    unique_keys:
+        target: [target]

src/mibew/configs/routing.yml

@@ -759,6 +759,13 @@ update_run:
         _access_check: Mibew\AccessControl\Check\PermissionsCheck
         _access_permissions: [CAN_ADMINISTRATE]
 
+update_check:
+    path: /update/check
+    defaults:
+        _controller: Mibew\Controller\UpdateController::checkUpdatesAction
+        _access_check: Mibew\AccessControl\Check\PermissionsCheck
+        _access_permissions: [CAN_ADMINISTRATE]
+
 ## Users (visitors avaiting page)
 users:
     path: /operator/users

src/mibew/js/source/about.js

@@ -1,40 +0,0 @@
-/*!
- * This file is a part of Mibew Messenger.
- *
- * Copyright 2005-2015 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-(function (Mibew, $) {
-    Mibew.updateVersion = function(data) {
-        if (!data.core || !data.core.stable) {
-            return;
-        }
-
-        $(document).ready(function() {
-            var currentVersion = $("#current-version").html(),
-                core = data.core.stable;
-
-            if (currentVersion != core.version) {
-                if (currentVersion < core.version) {
-                    $("#current-version").css("color", "red");
-                }
-                $("#latest-version").html(core.version + ", Download <a href=\"" + core.download + "\">" + core.title + "</a>");
-            } else {
-                $("#current-version").css("color", "green");
-                $("#latest-version").html(core.version);
-            }
-        });
-    }
-})(Mibew, jQuery);

src/mibew/libs/classes/Mibew/Controller/AboutController.php

@@ -19,7 +19,7 @@
 
 namespace Mibew\Controller;
 
-use Mibew\Asset\AssetManagerInterface;
+use Mibew\Maintenance\AvailableUpdate;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
@@ -43,16 +43,11 @@ class AboutController extends AbstractController
                 'version' => MIBEW_VERSION,
                 'title' => getlocal('About'),
                 'menuid' => 'about',
+                'availableUpdates' => $this->getAvailableUpdates(),
             ),
             prepare_menu($this->getOperator())
         );
 
-        $this->getAssetManager()->attachJs('js/compiled/about.js');
-        $this->getAssetManager()->attachJs(
-            'https://mibew.org/api/updates',
-            AssetManagerInterface::ABSOLUTE_URL
-        );
-
         return $this->render('about', $page);
     }
 
@@ -68,7 +63,7 @@ class AboutController extends AbstractController
      */
     protected function getExtensionsInfo()
     {
-        $required_extensions = array('PDO', 'pdo_mysql', 'gd');
+        $required_extensions = array('PDO', 'pdo_mysql', 'gd', 'curl');
         $info = array();
         foreach ($required_extensions as $ext) {
             if (!extension_loaded($ext)) {
@@ -86,4 +81,39 @@ class AboutController extends AbstractController
 
         return $info;
     }
+
+    /**
+     * Builds list of available updates to display in the template.
+     *
+     * @return array List of updates data. Each item of the list is associative
+     * array with the following keys:
+     *   - "title": string, title of the update.
+     *   - "version": string, the latest available version.
+     *   - "url": string, URL of the page the updated version can be downloaded
+     *     from.
+     *   - "description": string, description of the update.
+     */
+    protected function getAvailableUpdates()
+    {
+        $updates = AvailableUpdate::all();
+        if (!$updates) {
+            return array();
+        }
+
+        $data = array();
+        foreach ($updates as $update) {
+            $title = ($update->target == 'core')
+                ? 'Mibew'
+                : getlocal('{0} plugin', array($update->target));
+
+            $data[] = array(
+                'title' => $title,
+                'version' => $update->version,
+                'url' => $update->url,
+                'description' => $update->description,
+            );
+        }
+
+        return $data;
+    }
 }

src/mibew/libs/classes/Mibew/Controller/Settings/FeaturesController.php

@@ -111,6 +111,7 @@ class FeaturesController extends AbstractController
             'showonlineoperators',
             'enablecaptcha',
             'trackoperators',
+            'autocheckupdates',
         );
     }
 }

src/mibew/libs/classes/Mibew/Controller/UpdateController.php

@@ -19,7 +19,9 @@
 
 namespace Mibew\Controller;
 
+use Mibew\Maintenance\UpdateChecker;
 use Mibew\Maintenance\Updater;
+use Mibew\Settings;
 use Mibew\Style\PageStyle;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -33,6 +35,11 @@ class UpdateController extends AbstractController
      */
     protected $updater = null;
 
+    /**
+     * @var UpdateChecker|null
+     */
+    protected $updateChecker = null;
+
     /**
      * Renders update intro page.
      *
@@ -74,6 +81,26 @@ class UpdateController extends AbstractController
         return $this->render('update_progress', $parameters);
     }
 
+    /**
+     * Runs the Update checker.
+     *
+     * @param Request $request Incoming request.
+     * @return Response|string Rendered page contents or Symfony's response
+     *   object.
+     */
+    public function checkUpdatesAction(Request $request)
+    {
+        $checker = $this->getUpdateChecker();
+        $success = $checker->run();
+        if (!$success) {
+            foreach ($checker->getErrors() as $error) {
+                trigger_error('Update checking failed: ' . $error, E_USER_WARNING);
+            }
+        }
+
+        return $this->redirect($this->generateUrl('about'));
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -99,4 +126,22 @@ class UpdateController extends AbstractController
 
         return $this->updater;
     }
+
+    /**
+     * Returns an instance of Update Checker.
+     *
+     * @return UpdateChecker
+     */
+    protected function getUpdateChecker()
+    {
+        if (is_null($this->updateChecker)) {
+            $this->updateChecker = new UpdateChecker();
+            $id = Settings::get('_instance_id');
+            if ($id) {
+                $this->updateChecker->setInstanceId($id);
+            }
+        }
+
+        return $this->updateChecker;
+    }
 }

src/mibew/libs/classes/Mibew/Maintenance/AvailableUpdate.php

@@ -0,0 +1,253 @@
+<?php
+/*
+ * This file is a part of Mibew Messenger.
+ *
+ * Copyright 2005-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Mibew\Maintenance;
+
+use Mibew\Database;
+
+/**
+ * Represents a record about available update with all necessary info.
+ */
+class AvailableUpdate
+{
+    /**
+     * Unique (for the current Mibew instance) update ID.
+     *
+     * @type int
+     */
+    public $id;
+
+    /**
+     * String representing update target.
+     *
+     * It can be equal to either "core" or fully qualified plugin's name.
+     *
+     * @var string
+     */
+    public $target;
+
+    /**
+     * The latest version the core/plugin can be updated to.
+     *
+     * @type string
+     */
+    public $version;
+
+    /**
+     * The URL the update can be downloaded from.
+     *
+     * @type string
+     */
+    public $url;
+
+    /**
+     * Arbitrary description of the update.
+     *
+     * @type string
+     */
+    public $description;
+
+    /**
+     * Loads update by its ID.
+     *
+     * @param int $id ID of the update to load
+     * @return boolean|AvailableUpdate Returns an AvailableUpdate instance or
+     * boolean false on failure.
+     */
+    public static function load($id)
+    {
+        // Check $id
+        if (empty($id)) {
+            return false;
+        }
+
+        // Load update's info
+        $info = Database::getInstance()->query(
+            "SELECT * FROM {availableupdate} WHERE id = :id",
+            array(':id' => $id),
+            array('return_rows' => Database::RETURN_ONE_ROW)
+        );
+
+        // There is no update with such id in database
+        if (!$info) {
+            return false;
+        }
+
+        // Create and populate update object
+        $update = new self();
+        $update->populateFromDbFields($info);
+
+        return $update;
+    }
+
+    /**
+     * Loads update by its target.
+     *
+     * @param string $target Target of the update to load.
+     * @return boolean|AvailableUpdate Returns an AvailableUpdate instance or
+     * boolean false on failure.
+     */
+    public static function loadByTarget($target)
+    {
+        // Check the target
+        if (empty($target)) {
+            return false;
+        }
+
+        // Load update info
+        $info = Database::getInstance()->query(
+            "SELECT * FROM {availableupdate} WHERE target = :target",
+            array(':target' => $target),
+            array('return_rows' => Database::RETURN_ONE_ROW)
+        );
+
+        // There is no update with such target in database
+        if (!$info) {
+            return false;
+        }
+
+        // Create and populate update object
+        $update = new self();
+        $update->populateFromDbFields($info);
+
+        return $update;
+    }
+
+    /**
+     * Loads available updates.
+     *
+     * @return array List of AvailableUpdate instances.
+     *
+     * @throws \RuntimeException If something went wrong and the list could not
+     *   be loaded.
+     */
+    public static function all()
+    {
+        $rows = Database::getInstance()->query(
+            "SELECT * FROM {availableupdate}",
+            null,
+            array('return_rows' => Database::RETURN_ALL_ROWS)
+        );
+
+        if ($rows === false) {
+            throw new \RuntimeException('List of available updates cannot be retrieved.');
+        }
+
+        $updates = array();
+        foreach ($rows as $item) {
+            $update = new self();
+            $update->populateFromDbFields($item);
+            $updates[] = $update;
+        }
+
+        return $updates;
+    }
+
+    /**
+     * Class constructor.
+     */
+    public function __construct()
+    {
+        // Set default values
+        $this->id = false;
+        $this->target = null;
+        $this->version = null;
+        $this->url = '';
+        $this->description = '';
+    }
+
+    /**
+     * Remove record about available update from the database.
+     */
+    public function delete()
+    {
+        if (!$this->id) {
+            throw new \RuntimeException('You cannot delete an update without id');
+        }
+
+        Database::getInstance()->query(
+            "DELETE FROM {availableupdate} WHERE id = :id LIMIT 1",
+            array(':id' => $this->id)
+        );
+    }
+
+    /**
+     * Save the update to the database.
+     */
+    public function save()
+    {
+        $db = Database::getInstance();
+
+        if (!$this->target) {
+            throw new \RuntimeException('Update\'s target was not set');
+        }
+
+        if (!$this->url) {
+            throw new \RuntimeException('Update\'s URL was not set');
+        }
+
+        if (!$this->version) {
+            throw new \RuntimeException('Update\'s version was not set');
+        }
+
+        if (!$this->id) {
+            // This update is new.
+            $db->query(
+                ("INSERT INTO {availableupdate} (target, version, url, description) "
+                    . "VALUES (:target, :version, :url, :description)"),
+                array(
+                    ':target' => $this->target,
+                    ':version' => $this->version,
+                    ':url' => $this->url,
+                    ':description' => $this->description,
+                )
+            );
+            $this->id = $db->insertedId();
+        } else {
+            // Update existing update
+            $db->query(
+                ("UPDATE {availableupdate} SET target = :target, url = :url, "
+                    . "version = :version, description = :description "
+                    . "WHERE id = :id"),
+                array(
+                    ':id' => $this->id,
+                    ':target' => $this->target,
+                    ':version' => $this->version,
+                    ':url' => $this->url,
+                    ':description' => $this->description,
+                )
+            );
+        }
+    }
+
+    /**
+     * Sets update's fields according to the fields from Database.
+     *
+     * @param array $db_fields Associative array of database fields which keys
+     *   are fields names and the values are fields values.
+     */
+    protected function populateFromDbFields($db_fields)
+    {
+        $this->id = $db_fields['id'];
+        $this->target = $db_fields['target'];
+        $this->version = $db_fields['version'];
+        $this->url = $db_fields['url'];
+        $this->description = $db_fields['description'];
+    }
+}

src/mibew/libs/classes/Mibew/Maintenance/CronWorker.php

@@ -36,6 +36,13 @@ class CronWorker
      */
     protected $cache = null;
 
+    /**
+     * An instance of update checker.
+     *
+     * @var UpdateChecker|null
+     */
+    protected $updateChecker = null;
+
     /**
      * List of errors.
      *
@@ -54,10 +61,15 @@ class CronWorker
      * Class constructor.
      *
      * @param PoolInterface $cache An instance of cache pool.
+     * @param UpdateChecker $update_checker An instance of update checker.
      */
-    public function __construct(PoolInterface $cache)
+    public function __construct(PoolInterface $cache, UpdateChecker $update_checker = null)
     {
         $this->cache = $cache;
+
+        if (!is_null($update_checker)) {
+            $this->updateChecker = $update_checker;
+        }
     }
 
     /**
@@ -71,6 +83,9 @@ class CronWorker
         try {
             set_time_limit(0);
 
+            // Update time of last cron run
+            Settings::set('_last_cron_run', time());
+
             // Remove stale cached items
             $this->cache->purge();
 
@@ -83,8 +98,18 @@ class CronWorker
             $dispatcher = EventDispatcher::getInstance();
             $dispatcher->triggerEvent(Events::CRON_RUN);
 
-            // Update time of last cron run
+            if (Settings::get('autocheckupdates') == '1') {
-            Settings::set('_last_cron_run', time());
+                // Run the update checker
+                $update_checker = $this->getUpdateChecker();
+                if (!$update_checker->run()) {
+                    $this->errors = array_merge(
+                        $this->errors,
+                        $update_checker->getErrors()
+                    );
+
+                    return false;
+                }
+            }
         } catch (\Exception $e) {
             $this->log[] = $e->getMessage();
 
@@ -114,4 +139,24 @@ class CronWorker
     {
         return $this->log;
     }
+
+    /**
+     * Retrives an instance of Update Checker attached to the worker.
+     *
+     * If there was no attached checker it creates a new one.
+     *
+     * @return UpdateChecker
+     */
+    protected function getUpdateChecker()
+    {
+        if (is_null($this->updateChecker)) {
+            $this->updateChecker = new UpdateChecker();
+            $id = Settings::get('_instance_id');
+            if ($id) {
+                $this->updateChecker->setInstanceId($id);
+            }
+        }
+
+        return $this->updateChecker;
+    }
 }

src/mibew/libs/classes/Mibew/Maintenance/Installer.php

@@ -440,6 +440,46 @@ class Installer
             return false;
         }
 
+        // Generate Unique ID for Mibew Instance
+        try {
+            list($count) = $db->query(
+                'SELECT COUNT(*) FROM {config} WHERE vckey = :key',
+                array(':key' => '_instance_id'),
+                array(
+                    'return_rows' => Database::RETURN_ONE_ROW,
+                    'fetch_type' => Database::FETCH_NUM,
+                )
+            );
+
+            if ($count == 0) {
+                $db->query(
+                    'INSERT INTO {config} (vckey, vcvalue) VALUES (:key, :value)',
+                    array(
+                        ':key' => '_instance_id',
+                        ':value' => Utils::generateInstanceId(),
+                    )
+                );
+            } else {
+                // The option is already in the database. It seems that
+                // something went wrong with the previous installation attempt.
+                // Just update the instance ID.
+                $db->query(
+                    'UPDATE {config} SET vcvalue = :value WHERE vckey = :key',
+                    array(
+                        ':key' => '_instance_id',
+                        ':value' => Utils::generateInstanceId(),
+                    )
+                );
+            }
+        } catch (\Exception $e) {
+            $this->errors[] = getlocal(
+                'Cannot store instance ID. Error {0}',
+                array($e->getMessage())
+            );
+
+            return false;
+        }
+
         return true;
     }
 
@@ -489,7 +529,7 @@ class Installer
      */
     protected function checkPhpExtensions()
     {
-        $extensions = array('PDO', 'pdo_mysql', 'gd');
+        $extensions = array('PDO', 'pdo_mysql', 'gd', 'curl');
 
         foreach ($extensions as $ext) {
             if (!extension_loaded($ext)) {

src/mibew/libs/classes/Mibew/Maintenance/UpdateChecker.php

@@ -0,0 +1,371 @@
+<?php
+/*
+ * This file is a part of Mibew Messenger.
+ *
+ * Copyright 2005-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Mibew\Maintenance;
+
+use Mibew\Plugin\Utils as PluginUtils;
+use Mibew\Plugin\PluginInfo;
+
+/**
+ * Encapsulates available updates checking process.
+ */
+class UpdateChecker
+{
+    /**
+     * URL of the updates server.
+     *
+     * @var string|null
+     */
+    private $url = null;
+
+    /**
+     * Unique 64 character length ID of the Mibew instance.
+     *
+     * @var string
+     */
+    private $instanceId = '';
+
+    /**
+     * A cache for plugins info array.
+     *
+     * @var array|null
+     */
+    private $pluginsInfo = null;
+
+    /**
+     * List of errors that took place during updates checking.
+     *
+     * Each item of the list is a error string.
+     *
+     * @var array
+     */
+    private $errors = [];
+
+    /**
+     * Sets URL of updates server.
+     *
+     * @param string $url New updates server's URL
+     */
+    public function setUrl($url)
+    {
+        $this->url = $url;
+    }
+
+    /**
+     * Retrieves URL of updates server.
+     *
+     * @return string
+     */
+    public function getUrl()
+    {
+        return is_null($this->url)
+            ? 'https://mibew.org/api2/updates.json'
+            : $this->url;
+    }
+
+    /**
+     * Sets Unique ID of the Mibew instance.
+     *
+     * @param string $id Unique ID that is 64 characters length at most.
+     * @throws \InvalidArgumentException
+     */
+    public function setInstanceId($id)
+    {
+        if (strlen($id) > 64) {
+            throw new \InvalidArgumentException(
+                'The ID is too long. It can be 64 characters length at most.'
+            );
+        }
+
+        // Make sure the ID is always a string.
+        $this->instanceId = $id ?: '';
+    }
+
+    /**
+     * Retrieve Unique ID of the Mibew instance.
+     *
+     * @return string
+     */
+    public function getInstanceId()
+    {
+        return $this->instanceId;
+    }
+
+    /**
+     * Retrieves list of errors that took place during update checking process.
+     *
+     * @return array List of errors. Each item in the list is a error string.
+     */
+    public function getErrors()
+    {
+        return $this->errors;
+    }
+
+    /**
+     * Runs update checking process.
+     *
+     * @return boolean False on error and true otherwise. To get more info about
+     * error call {@link UpdateChecker::getErrors()} method.
+     */
+    public function run()
+    {
+        $ch = curl_init($this->getUrl());
+
+        // TODO: set timeouts
+        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
+        curl_setopt($ch, CURLOPT_POST, true);
+        curl_setopt($ch, CURLOPT_MAXREDIRS, 5);
+
+        $json = json_encode($this->getSystemInfo());
+        curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
+        curl_setopt($ch, CURLOPT_HTTPHEADER, array(
+            'Accept: application/json',
+            'Content-Type: application/json',
+            'Content-Length: ' . strlen($json)
+        ));
+        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+
+        $body = curl_exec($ch);
+        $response_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        $curl_errno = curl_errno($ch);
+        $curl_error = curl_error($ch);
+        curl_close($ch);
+
+        if ($curl_errno !== 0) {
+            // cURL request failed.
+            $this->errors[] = sprintf(
+                'cURL error (#%u): %s',
+                $curl_errno,
+                $curl_error
+            );
+
+            return false;
+        }
+
+        if ($response_code != 200) {
+            // Unexpected HTTP recieved.
+            $this->errors[] = sprintf(
+                'Update server returns %u HTTP code instead of 200',
+                $response_code
+            );
+
+            return false;
+        }
+
+        $updates = json_decode($body, true);
+        $json_error = json_last_error();
+        if ($json_error !== JSON_ERROR_NONE) {
+            // Cannot parse JSON result.
+            $this->errors[] = $this->formatJsonError($json_error);
+
+            return false;
+        }
+
+        if (!$updates) {
+            // There are no available updates.
+            return true;
+        }
+
+        return $this->processUpdates($updates);
+    }
+
+    /**
+     * Retrieves set of system info that will be sent to updates server.
+     *
+     * @return array
+     */
+    protected function getSystemInfo()
+    {
+        $info = array(
+            'core' => MIBEW_VERSION,
+            'plugins' => $this->getPluginsInfo(),
+        );
+
+        // Attach Instance ID to the info but only if it's not empty.
+        $id = $this->getInstanceId();
+        if ($id) {
+            $info['uid'] = $id;
+        }
+
+        return $info;
+    }
+
+    /**
+     * Retrieves info about plugins available in the system.
+     *
+     * @return array Associative array of plugins info. Each key of the array is
+     * fully qualified plugin's name and each value is an array with the
+     * fillowing keys:
+     *  - "version": string, version of the plugin which presents in the system.
+     *  - "installed": boolean, indicates if the plugin is installed.
+     *  - "enabled": boolean, indicates if the plugin is enabled.
+     */
+    protected function getPluginsInfo()
+    {
+        if (is_null($this->pluginsInfo)) {
+            $this->pluginsInfo = [];
+            $names = PluginUtils::discoverPlugins();
+            foreach ($names as $plugin_name) {
+                $info = new PluginInfo($plugin_name);
+                $this->pluginsInfo[$plugin_name] = array(
+                    'version' => $info->getVersion(),
+                    'installed' => $info->getState()->installed,
+                    'enabled' => $info->getState()->enabled,
+                );
+            }
+        }
+
+        return $this->pluginsInfo;
+    }
+
+    /**
+     * Performs all actions that are needed to prepare store available updates.
+     *
+     * @param array $updates Asscociative array of available updates that is
+     * retrieved from the updates server.
+     * @return boolean False on error and true otherwise. To get more info about
+     * error call {@link UpdateChecker::getErrors()} method.
+     */
+    protected function processUpdates($updates)
+    {
+        // Process updates of the core.
+        if (version_compare($updates['core']['version'], MIBEW_VERSION) > 0) {
+            $update = $updates['core'];
+            // Save info about update for the core only if its version changed
+            $success = $this->saveUpdate(
+                'core',
+                $update['version'],
+                $update['download'],
+                empty($update['description']) ? '' : $update['description']
+            );
+            if (!$success) {
+                // Something went wrong. The error is already logged so just
+                // notify the outer code.
+                return false;
+            }
+        }
+
+        // Process plugins updates.
+        $plugins_info = $this->getPluginsInfo();
+        foreach ($updates['plugins'] as $plugin_name => $update) {
+            if (!isset($plugins_info[$plugin_name])) {
+                // It's strange. We recieve update info for a plugin that does
+                // not exist in the system. Just do nothing.
+                continue;
+            }
+
+            $info = $plugins_info[$plugin_name];
+
+            if (version_compare($update['version'], $info['version']) <= 0) {
+                // Version of the plugin is not updated. Just do nothing.
+                continue;
+            }
+
+            // Save the update
+            $success = $this->saveUpdate(
+                $plugin_name,
+                $update['version'],
+                $update['download'],
+                empty($update['description']) ? '' : $update['description']
+            );
+            if (!$success) {
+                // Something went wrong. The error is already logged so just
+                // notify the outer code.
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Saves record about available update in the database.
+     *
+     * @param string $target Update's target. Can be either "core" or fully
+     * qualified plugin's name.
+     * @param string $version The latest version at the updates server.
+     * @param string $url URL of the page where the update can be downloaded.
+     * @param string $description Arbitrary update's description.
+     * @return boolean False on failure and true otherwise. To get more info
+     * about the error call {@link UpdateChecker::getErrors()} method.
+     */
+    protected function saveUpdate($target, $version, $url, $description = '')
+    {
+        try {
+            $update = AvailableUpdate::loadByTarget($target);
+            if (!$update) {
+                // There is no such update in the database. Create a new one.
+                $update = new AvailableUpdate();
+                $update->target = $target;
+            }
+
+            $update->version = $version;
+            $update->url = $url;
+            $update->description = $description;
+
+            $update->save();
+        } catch (\Exception $e) {
+            $this->errors[] = 'Cannot save available update: ' + $e->getMessage();
+
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Builds human-readable message about error in json_* PHP's function.
+     *
+     * @param int $error_code Error code returned by json_last_error
+     * @return string Human-readable error message.
+     */
+    protected function formatJsonError($error_code)
+    {
+        $errors = array(
+            JSON_ERROR_DEPTH => 'JSON_ERROR_DEPTH',
+            JSON_ERROR_STATE_MISMATCH => 'JSON_ERROR_STATE_MISMATCH',
+            JSON_ERROR_CTRL_CHAR => 'JSON_ERROR_CTRL_CHAR',
+            JSON_ERROR_SYNTAX => 'JSON_ERROR_SYNTAX',
+        );
+
+        // Following constants may be unavailable for the current PHP version.
+        if (defined('JSON_ERROR_UTF8')) {
+            $errors[JSON_ERROR_UTF8] = 'JSON_ERROR_UTF8';
+        }
+
+        if (defined('JSON_ERROR_RECURSION')) {
+            $errors[JSON_ERROR_RECURSION] = 'JSON_ERROR_RECURSION';
+        }
+
+        if (defined('JSON_ERROR_INF_OR_NAN')) {
+            $errors[JSON_ERROR_INF_OR_NAN] = 'JSON_ERROR_INF_OR_NAN';
+        }
+
+        if (defined('JSON_ERROR_UNSUPPORTED_TYPE')) {
+            $errors[JSON_ERROR_UNSUPPORTED_TYPE] = 'JSON_ERROR_UNSUPPORTED_TYPE';
+        }
+
+        $msg = isset($errors[$error_code]) ? $errors[$error_code] : 'UNKNOWN';
+
+        return sprintf(
+            'Could not parse response from update server. The error is: "%s"',
+            $msg
+        );
+    }
+}

src/mibew/libs/classes/Mibew/Maintenance/Updater.php

@@ -332,14 +332,33 @@ class Updater
             return false;
         }
 
-        // Alter locale table.
         try {
+            // Alter locale table.
             $db->query('ALTER TABLE {locale} ADD COLUMN name varchar(128) NOT NULL DEFAULT "" AFTER code');
             $db->query('ALTER TABLE {locale} ADD COLUMN rtl tinyint NOT NULL DEFAULT 0');
             $db->query('ALTER TABLE {locale} ADD COLUMN time_locale varchar(128) NOT NULL DEFAULT "en_US"');
             $db->query('ALTER TABLE {locale} ADD COLUMN date_format text');
 
             $db->query('ALTER TABLE {locale} ADD UNIQUE KEY code (code)');
+
+            // Create a table for available updates.
+            $db->query('CREATE TABLE {availableupdate} ( '
+                . 'id INT NOT NULL auto_increment PRIMARY KEY, '
+                . 'target varchar(255) NOT NULL, '
+                . 'version varchar(255) NOT NULL, '
+                . 'url text, '
+                . 'description text, '
+                . 'UNIQUE KEY target (target) '
+                . ') charset utf8 ENGINE=InnoDb');
+
+            // Generate Unique ID of Mibew instance.
+            $db->query(
+                'INSERT INTO {config} (vckey, vcvalue) VALUES (:key, :value)',
+                array(
+                    ':key' => '_instance_id',
+                    ':value' => Utils::generateInstanceId(),
+                )
+            );
         } catch (\Exception $e) {
             $this->errors[] = getlocal('Cannot update tables: {0}', $e->getMessage());
 

src/mibew/libs/classes/Mibew/Maintenance/Utils.php

@@ -101,6 +101,40 @@ class Utils
         return $updates;
     }
 
+    /**
+     * Generates random unique 64 characters length ID for Mibew instance.
+     *
+     * WARNING: This ID should not be used for any security/cryptographic. If
+     * you need an ID for such purpose you have to use PHP's
+     * {@link openssl_random_pseudo_bytes()} function instead.
+     *
+     * @return string
+     */
+    public static function generateInstanceId()
+    {
+        $chars = '0123456789abcdefghijklmnopqrstuvwxyz';
+        $rnd = (string)microtime(true);
+
+        // Add ten random characters before and after the timestamp
+        $max_char = strlen($chars) - 1;
+        for ($i = 0; $i < 10; $i++) {
+            $rnd = $chars[rand(0, $max_char)] . $rnd . $chars[rand(0, $max_char)];
+        }
+
+        if (function_exists('hash')) {
+            // There is hash function that can give us 64-length hash.
+            return hash('sha256', $rnd);
+        }
+
+        // We should build random 64 character length hash using old'n'good md5
+        // function.
+        $middle = (int)floor(strlen($rnd) / 2);
+        $rnd_left = substr($rnd, 0, $middle);
+        $rnd_right = substr($rnd, $middle);
+
+        return md5($rnd_left) . md5($rnd_right);
+    }
+
     /**
      * This class should not be instantiated
      */

src/mibew/libs/classes/Mibew/Settings.php

@@ -97,6 +97,7 @@ class Settings
             'surveyaskgroup' => '1',
             'surveyaskmessage' => '0',
             'enablepopupnotification' => '0',
+            'autocheckupdates' => '1', /* Check updates automatically */
             'showonlineoperators' => '0',
             'enablecaptcha' => '0',
             'online_timeout' => 30, /* Timeout (in seconds) when online operator becomes offline */
@@ -114,6 +115,10 @@ class Settings
             // underscore sign(_).
             // Unix timestamp when cron job ran last time.
             '_last_cron_run' => 0,
+            // Random unique ID which is used for getting info about new
+            // updates. This value is initialized during Installation or Update
+            // process.
+            '_instance_id' => '',
         );
 
         // Load values from database

src/mibew/styles/pages/default/templates_src/server_side/about.handlebars

@@ -22,11 +22,6 @@
 
                     <br/>
 
-                    <h3>{{l10n "Latest version:"}}</h3>
-                    <div id="latest-version"></div>
-
-                    <br/>
-
                     <h3>{{l10n "Installed localizations:"}}</h3>
                     {{#each localizations}}
                         {{this}}
@@ -36,6 +31,26 @@
 
                     <h3>{{l10n "Environment:"}}</h3>
                     PHP {{phpVersion}} {{#each extensions}}{{@key}}{{#if loaded}}{{#if version}}/{{version}}{{/if}}{{else}}/absent{{/if}} {{/each}}
+
+                    <br/><br/>
+
+                    <h2>{{l10n "Available updates"}}</h2>
+                    {{#if availableUpdates}}
+                        {{#each availableUpdates}}
+                            <h3>{{title}} ({{version}})</h3>
+                            {{#if description}}
+                                <div>{{description}}</div>
+                            {{/if}}
+                            <div>
+                                <a href="{{url}}">Download</a>
+                            </div>
+
+                            <br/>
+                        {{/each}}
+                    {{else}}
+                        There is no available updates.<br/><br/>
+                    {{/if}}
+                    <a href="{{route "update_check"}}">{{l10n "Check for available updates"}}</a>
                 </div>
 
                 <div class="form-footer">

src/mibew/styles/pages/default/templates_src/server_side/settings_features.handlebars

@@ -172,6 +172,15 @@
                                 <br clear="all"/>
                             </div>
 
+                            <div class="field">
+                                <label for="autocheck-updates" class="field-label">{{l10n "Check updates automatically"}}</label>
+                                <div class="field-value">
+                                    <input id="autocheck-updates" type="checkbox" name="autocheckupdates" value="on"{{#if formautocheckupdates}} checked="checked"{{/if}}{{#unless canmodify}} disabled="disabled"{{/unless}}/>
+                                </div>
+                                <label for="autocheck-updates" class="field-description"> &mdash; {{l10n "System will check updates for the core and plugins automatically using cron"}}</label>
+                                <br clear="all"/>
+                            </div>
+
                             {{#if canmodify}}
                                 <div class="form-button">
                                     <input type="submit" name="save" class="submit-button-background save-button" value="{{l10n "Save"}}"/>