avoid large amounts of notifications being added to the session (#17736)

* impose limit on notification message size when logging to notifications

* if in memory notification count exceeds max notification size in session, do not attempt to new ones it to the session

* Detect when session was too large to read and provide warning to user.

* add some tests for Notification\ManagerTest.php

* add tests for relevant DbTable members

* Change session data column type to allow larger session data values.

* update to rc3

* trigger new build?

* fix namespace

* fix test namespaces

* bump version correctly

7 files changed, 95 insertions, 12 deletions

diff --git a/core/Db/Schema/Mysql.php b/core/Db/Schema/Mysql.php
index c7afaa6d87..940f694e70 100644
--- a/core/Db/Schema/Mysql.php
+++ b/core/Db/Schema/Mysql.php
@@ -275,7 +275,7 @@ class Mysql implements SchemaInterface
                                 id VARCHAR( 191 ) NOT NULL,
                                 modified INTEGER,
                                 lifetime INTEGER,
-                                data TEXT,
+                                data MEDIUMTEXT,
                                   PRIMARY KEY ( id )
                                 ) ENGINE=$engine DEFAULT CHARSET=$charset
             ",
diff --git a/core/Notification/Manager.php b/core/Notification/Manager.php
index a621f27bfd..6e1924e873 100644
--- a/core/Notification/Manager.php
+++ b/core/Notification/Manager.php
@@ -18,6 +18,7 @@ use Piwik\Session\SessionNamespace;
  */
 class Manager
 {
+    const MAX_NOTIFICATIONS_IN_SESSION = 30;
     /**
      * @var SessionNamespace
      */
@@ -36,6 +37,8 @@ class Manager
      *                           element ID. It can only contain alphanumeric characters (underscores can
      *                           be used).
      * @param Notification $notification The notification to post.
+     * @return bool true if the notification was added, false if it was ignored because there were too many
+     *                   pending ones.
      * @api
      */
     public static function notify($id, Notification $notification)
@@ -43,7 +46,7 @@ class Manager
         self::checkId($id);
 
         self::removeOldestNotificationsIfThereAreTooMany();
-        self::addNotification($id, $notification);
+        return self::addNotification($id, $notification);
     }
 
     /**
@@ -103,7 +106,7 @@ class Manager
             throw new \Exception('Notification ID is empty.');
         }
 
-        if (!preg_match('/^(\w)*$/', $id)) {
+        if (!preg_match('/^\w*$/', $id)) {
             throw new \Exception('Invalid Notification ID given. Only word characters (AlNum + underscore) allowed.');
         }
     }
@@ -112,9 +115,15 @@ class Manager
     {
         self::saveNotificationAcrossUiRequestsIfNeeded($id, $notification);
 
+        if (count(self::$notifications) >= self::MAX_NOTIFICATIONS_IN_SESSION) {
+            return false;
+        }
+
         // we store all kinda notifications here so in case the session is not enabled or disabled later there is still
         // a chance it gets delivered to the UI during the same request.
         self::$notifications[$id] = $notification;
+
+        return true;
     }
 
     private static function saveNotificationAcrossUiRequestsIfNeeded($id, Notification $notification)
@@ -133,7 +142,7 @@ class Manager
             return;
         }
 
-        $maxNotificationsInSession = 30;
+        $maxNotificationsInSession = self::MAX_NOTIFICATIONS_IN_SESSION;
 
         $session = static::getSession();
 
@@ -200,4 +209,15 @@ class Manager
 
         return static::$session;
     }
+
+    public static function cancelAllNotifications()
+    {
+        self::$notifications = [];
+    }
+
+    // for tests
+    public static function getPendingInMemoryNotifications()
+    {
+        return self::$notifications;
+    }
 }
diff --git a/core/Session.php b/core/Session.php
index 4c09c3b6cb..641334676c 100644
--- a/core/Session.php
+++ b/core/Session.php
@@ -100,13 +100,7 @@ class Session extends Zend_Session
                 @ini_set('session.serialize_handler', 'php_serialize');
             }
 
-            $config = array(
-                'name'           => Common::prefixTable(DbTable::TABLE_NAME),
-                'primary'        => 'id',
-                'modifiedColumn' => 'modified',
-                'dataColumn'     => 'data',
-                'lifetimeColumn' => 'lifetime',
-            );
+            $config = self::getDbTableConfig();
 
             $saveHandler = new DbTable($config);
             if ($saveHandler) {
@@ -226,4 +220,15 @@ class Session extends Zend_Session
         Common::sendHeader($headerStr);
         return $headerStr;
     }
+
+    public static function getDbTableConfig()
+    {
+        return array(
+            'name'           => Common::prefixTable(DbTable::TABLE_NAME),
+            'primary'        => 'id',
+            'modifiedColumn' => 'modified',
+            'dataColumn'     => 'data',
+            'lifetimeColumn' => 'lifetime',
+        );
+    }
 }
diff --git a/core/Session/SaveHandler/DbTable.php b/core/Session/SaveHandler/DbTable.php
index 46012cc216..52bbeeb37f 100644
--- a/core/Session/SaveHandler/DbTable.php
+++ b/core/Session/SaveHandler/DbTable.php
@@ -23,6 +23,8 @@ use Zend_Session_SaveHandler_Interface;
  */
 class DbTable implements Zend_Session_SaveHandler_Interface
 {
+    public static $wasSessionToLargeToRead = false;
+
     protected $config;
     protected $maxLifetime;
 
diff --git a/core/Session/SessionAuth.php b/core/Session/SessionAuth.php
index 19e7e24e19..bff91c113e 100644
--- a/core/Session/SessionAuth.php
+++ b/core/Session/SessionAuth.php
@@ -13,10 +13,12 @@ use Piwik\Auth;
 use Piwik\AuthResult;
 use Piwik\Common;
 use Piwik\Config;
+use Piwik\Container\StaticContainer;
 use Piwik\Date;
 use Piwik\Plugins\UsersManager\Model;
 use Piwik\Plugins\UsersManager\Model as UsersModel;
 use Piwik\Session;
+use Psr\Log\LoggerInterface;
 
 /**
  * Validates already authenticated sessions.
@@ -94,6 +96,8 @@ class SessionAuth implements Auth
         $sessionFingerprint = new SessionFingerprint();
         $userModel = $this->userModel;
 
+        $this->checkIfSessionFailedToRead();
+
         if ($this->isExpiredSession($sessionFingerprint)) {
             $sessionFingerprint->clear();
             return $this->makeAuthFailure();
@@ -231,4 +235,12 @@ class SessionAuth implements Auth
         $isExpired = Date::now()->getTimestampUTC() > $expirationTime;
         return $isExpired;
     }
+
+    private function checkIfSessionFailedToRead()
+    {
+        if (Session\SaveHandler\DbTable::$wasSessionToLargeToRead) {
+            StaticContainer::get(LoggerInterface::class)->warning(
+                "Too much data stored in the session so it could not be read properly. If you were logged out, this is why.");
+        }
+    }
 }
diff --git a/core/Updates/4.5.0-b1.php b/core/Updates/4.5.0-b1.php
new file mode 100644
index 0000000000..e79ebe7107
--- /dev/null
+++ b/core/Updates/4.5.0-b1.php
@@ -0,0 +1,43 @@
+<?php
+/**
+ * Matomo - free/libre analytics platform
+ *
+ * @link https://matomo.org
+ * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
+ *
+ */
+
+namespace Piwik\Updates;
+
+use Piwik\Updater;
+use Piwik\Updates as PiwikUpdates;
+use Piwik\Updater\Migration;
+use Piwik\Updater\Migration\Factory as MigrationFactory;
+
+class Updates_4_5_0_b1 extends PiwikUpdates
+{
+
+    /**
+     * @var MigrationFactory
+     */
+    private $migration;
+
+    public function __construct(MigrationFactory $factory)
+    {
+        $this->migration = $factory;
+    }
+
+    public function getMigrations(Updater $updater)
+    {
+        $migration1 = $this->migration->db->changeColumnType('session', 'data', 'MEDIUMTEXT');
+
+        return [
+            $migration1,
+        ];
+    }
+
+    public function doUpdate(Updater $updater)
+    {
+        $updater->executeMigrations(__FILE__, $this->getMigrations($updater));
+    }
+}
diff --git a/core/Version.php b/core/Version.php
index 8c0ebd1d8d..cd40ab0d9e 100644
--- a/core/Version.php
+++ b/core/Version.php
@@ -20,7 +20,8 @@ final class Version
      * The current Matomo version.
      * @var string
      */
-    const VERSION = '4.4.1';
+    const VERSION = '4.5.0-b1';
+
     const MAJOR_VERSION = 4;
 
     public function isStableVersion($version)