Fix session issues when local and database time differs (#1486132)

Improve performance by executing session gc on script shutdown, also call session_write_close() ASAP

4 files changed, 60 insertions, 67 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 9c67958a1..eaffa7099 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix session issues when local and database time differs (#1486132)
 - Fix thread cache syncronization/validation (#1489028)
 - Add option show_real_foldernames to disable localization of special folders
 - Fix database cache expunge issues (#1489149)
diff --git a/program/include/rcmail.php b/program/include/rcmail.php
index fd625ba4d..39d804d1f 100644
--- a/program/include/rcmail.php
+++ b/program/include/rcmail.php
@@ -749,11 +749,6 @@ class rcmail extends rcube
         $book->close();
     }
 
-    // before closing the database connection, write session data
-    if ($_SERVER['REMOTE_ADDR'] && is_object($this->session)) {
-      $this->session->write_close();
-    }
-
     // write performance stats to logs/console
     if ($this->config->get('devel_mode')) {
       if (function_exists('memory_get_usage'))
diff --git a/program/lib/Roundcube/rcube.php b/program/lib/Roundcube/rcube.php
index 8d17827be..21b49f49b 100644
--- a/program/lib/Roundcube/rcube.php
+++ b/program/lib/Roundcube/rcube.php
@@ -99,7 +99,6 @@ class rcube
     protected $texts;
     protected $caches = array();
     protected $shutdown_functions = array();
-    protected $expunge_cache = false;
 
 
     /**
@@ -462,7 +461,7 @@ class rcube
         // use database for storing session data
         $this->session = new rcube_session($this->get_dbh(), $this->config);
 
-        $this->session->register_gc_handler(array($this, 'gc_handler'));
+        $this->session->register_gc_handler(array($this, 'gc'));
         $this->session->set_secret($this->config->get('des_key') . dirname($_SERVER['SCRIPT_NAME']));
         $this->session->set_ip_check($this->config->get('ip_check'));
 
@@ -512,18 +511,6 @@ class rcube
 
 
     /**
-     * Garbage collector for cache entries.
-     * Set flag to expunge caches on shutdown
-     */
-    public function gc_handler()
-    {
-        // because this gc function is called before storage is initialized,
-        // we just set a flag to expunge storage cache on shutdown.
-        $this->expunge_cache = true;
-    }
-
-
-    /**
      * Runs garbage collector with probability based on
      * session settings. This is intended for environments
      * without a session.
@@ -922,12 +909,16 @@ class rcube
             call_user_func($function);
         }
 
-        if (is_object($this->smtp)) {
-            $this->smtp->disconnect();
+        // write session data as soon as possible and before
+        // closing database connection, don't do this before
+        // registered shutdown functions, they may need the session
+        // Note: this will run registered gc handlers (ie. cache gc)
+        if ($_SERVER['REMOTE_ADDR'] && is_object($this->session)) {
+            $this->session->write_close();
         }
 
-        if ($this->expunge_cache) {
-            $this->gc();
+        if (is_object($this->smtp)) {
+            $this->smtp->disconnect();
         }
 
         foreach ($this->caches as $cache) {
diff --git a/program/lib/Roundcube/rcube_session.php b/program/lib/Roundcube/rcube_session.php
index 4e0682749..615ec6f0e 100644
--- a/program/lib/Roundcube/rcube_session.php
+++ b/program/lib/Roundcube/rcube_session.php
@@ -32,6 +32,7 @@ class rcube_session
     private $ip;
     private $start;
     private $changed;
+    private $time_diff = 0;
     private $reloaded = false;
     private $unsets = array();
     private $gc_handlers = array();
@@ -93,7 +94,7 @@ class rcube_session
                 array($this, 'db_read'),
                 array($this, 'db_write'),
                 array($this, 'db_destroy'),
-                array($this, 'db_gc'));
+                array($this, 'gc'));
         }
     }
 
@@ -148,6 +149,11 @@ class rcube_session
         }
 
         session_write_close();
+
+        // write_close() is called on script shutdown, see rcube::shutdown()
+        // execute cleanup functionality if enabled by session gc handler
+        // we do this after closing the session for better performance
+        $this->gc_shutdown();
     }
 
 
@@ -161,14 +167,16 @@ class rcube_session
     public function db_read($key)
     {
         $sql_result = $this->db->query(
-            "SELECT vars, ip, changed FROM ".$this->db->table_name('session')
-            ." WHERE sess_id = ?", $key);
+            "SELECT vars, ip, changed, " . $this->db->now() . " AS ts"
+            . " FROM " . $this->db->table_name('session')
+            . " WHERE sess_id = ?", $key);
 
         if ($sql_result && ($sql_arr = $this->db->fetch_assoc($sql_result))) {
-            $this->changed = strtotime($sql_arr['changed']);
-            $this->ip      = $sql_arr['ip'];
-            $this->vars    = base64_decode($sql_arr['vars']);
-            $this->key     = $key;
+            $this->time_diff = time() - strtotime($sql_arr['ts']);
+            $this->changed   = strtotime($sql_arr['changed']);
+            $this->ip        = $sql_arr['ip'];
+            $this->vars      = base64_decode($sql_arr['vars']);
+            $this->key       = $key;
 
             return !empty($this->vars) ? (string) $this->vars : '';
         }
@@ -188,8 +196,9 @@ class rcube_session
      */
     public function db_write($key, $vars)
     {
-        $ts  = microtime(true);
-        $now = $this->db->fromunixtime((int)$ts);
+        $now   = $this->db->now();
+        $table = $this->db->table_name('session');
+        $ts    = microtime(true);
 
         // no session row in DB (db_read() returns false)
         if (!$this->key) {
@@ -207,22 +216,19 @@ class rcube_session
             $newvars = $this->_fixvars($vars, $oldvars);
 
             if ($newvars !== $oldvars) {
-                $this->db->query(
-                    sprintf("UPDATE %s SET vars=?, changed=%s WHERE sess_id=?",
-                        $this->db->table_name('session'), $now),
-                        base64_encode($newvars), $key);
+                $this->db->query("UPDATE $table "
+                    . "SET changed = $now, vars = ? WHERE sess_id = ?",
+                    base64_encode($newvars), $key);
             }
-            else if ($ts - $this->changed > $this->lifetime / 2) {
-                $this->db->query("UPDATE ".$this->db->table_name('session')
-                    ." SET changed=$now WHERE sess_id=?", $key);
+            else if ($ts - $this->changed + $this->time_diff > $this->lifetime / 2) {
+                $this->db->query("UPDATE $table SET changed = $now"
+                    . " WHERE sess_id = ?", $key);
             }
         }
         else {
-            $this->db->query(
-                sprintf("INSERT INTO %s (sess_id, vars, ip, created, changed) ".
-                    "VALUES (?, ?, ?, %s, %s)",
-                    $this->db->table_name('session'), $now, $now),
-                    $key, base64_encode($vars), (string)$this->ip);
+            $this->db->query("INSERT INTO $table (sess_id, vars, ip, created, changed)"
+                . " VALUES (?, ?, ?, $now, $now)",
+                $key, base64_encode($vars), (string)$this->ip);
         }
 
         return true;
@@ -282,25 +288,6 @@ class rcube_session
 
 
     /**
-     * Garbage collecting function
-     *
-     * @param string Session lifetime in seconds
-     * @return boolean True on success
-     */
-    public function db_gc($maxlifetime)
-    {
-        // just delete all expired sessions
-        $this->db->query(
-            sprintf("DELETE FROM %s WHERE changed < %s",
-                $this->db->table_name('session'), $this->db->fromunixtime(time() - $maxlifetime)));
-
-        $this->gc();
-
-        return true;
-    }
-
-
-    /**
      * Read session data from memcache
      *
      * @param string Session ID
@@ -376,11 +363,11 @@ class rcube_session
     /**
      * Execute registered garbage collector routines
      */
-    public function gc()
+    public function gc($maxlifetime)
     {
-        foreach ($this->gc_handlers as $fct) {
-            call_user_func($fct);
-        }
+        // move gc execution to the script shutdown function
+        // see rcube::shutdown() and rcube_session::write_close()
+        return $this->gc_enabled = $maxlifetime;
     }
 
 
@@ -402,6 +389,25 @@ class rcube_session
 
 
     /**
+     * Garbage collector handler to run on script shutdown
+     */
+    protected function gc_shutdown()
+    {
+        if ($this->gc_enabled) {
+            // just delete all expired sessions
+            if ($this->storage == 'db') {
+                $this->db->query("DELETE FROM " . $this->db->table_name('session')
+                    . " WHERE changed < " . $this->db->now(-$this->gc_enabled));
+            }
+
+            foreach ($this->gc_handlers as $fct) {
+                call_user_func($fct);
+            }
+        }
+    }
+
+
+    /**
      * Generate and set new session id
      *
      * @param boolean $destroy If enabled the current session will be destroyed