diff --git a/plugins/libkolab/lib/kolab_storage_cache.php b/plugins/libkolab/lib/kolab_storage_cache.php
index cdb373fd..6d50bf9a 100644
--- a/plugins/libkolab/lib/kolab_storage_cache.php
+++ b/plugins/libkolab/lib/kolab_storage_cache.php
@@ -1,728 +1,729 @@
 <?php
 
 /**
  * Kolab storage cache class providing a local caching layer for Kolab groupware objects.
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2012, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program 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 Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class kolab_storage_cache
 {
     private $db;
     private $imap;
     private $folder;
     private $uid2msg;
     private $objects;
     private $index = array();
     private $resource_uri;
     private $enabled = true;
     private $synched = false;
     private $synclock = false;
     private $ready = false;
     private $max_sql_packet = 1046576;  // 1 MB - 2000 bytes
     private $binary_cols = array('photo','pgppublickey','pkcs7publickey');
 
 
     /**
      * Default constructor
      */
     public function __construct(kolab_storage_folder $storage_folder = null)
     {
         $rcmail = rcube::get_instance();
         $this->db = $rcmail->get_dbh();
         $this->imap = $rcmail->get_storage();
         $this->enabled = $rcmail->config->get('kolab_cache', false);
 
         if ($this->enabled) {
             // remove sync-lock on script termination
             $rcmail->add_shutdown_function(array($this, '_sync_unlock'));
 
             // read max_allowed_packet from mysql config
             $this->max_sql_packet = min($this->db->get_variable('max_allowed_packet', 1048500), 4*1024*1024) - 2000;  // mysql limit or max 4 MB
         }
 
         if ($storage_folder)
             $this->set_folder($storage_folder);
     }
 
 
     /**
      * Connect cache with a storage folder
      *
      * @param kolab_storage_folder The storage folder instance to connect with
      */
     public function set_folder(kolab_storage_folder $storage_folder)
     {
         $this->folder = $storage_folder;
 
         if (empty($this->folder->name)) {
             $this->ready = false;
             return;
         }
 
         // compose fully qualified ressource uri for this instance
         $this->resource_uri = $this->folder->get_resource_uri();
         $this->ready = $this->enabled;
     }
 
 
     /**
      * Synchronize local cache data with remote
      */
     public function synchronize()
     {
         // only sync once per request cycle
         if ($this->synched)
             return;
 
         // increase time limit
         @set_time_limit(500);
 
         // lock synchronization for this folder or wait if locked
         $this->_sync_lock();
 
         // synchronize IMAP mailbox cache
         $this->imap->folder_sync($this->folder->name);
 
         // compare IMAP index with object cache index
         $imap_index = $this->imap->index($this->folder->name);
         $this->index = $imap_index->get();
 
         // determine objects to fetch or to invalidate
         if ($this->ready) {
             // read cache index
             $sql_result = $this->db->query(
                 "SELECT msguid, uid FROM kolab_cache WHERE resource=? AND type<>?",
                 $this->resource_uri,
                 'lock'
             );
 
             $old_index = array();
             while ($sql_arr = $this->db->fetch_assoc($sql_result)) {
                 $old_index[] = $sql_arr['msguid'];
                 $this->uid2msg[$sql_arr['uid']] = $sql_arr['msguid'];
             }
 
             // fetch new objects from imap
             foreach (array_diff($this->index, $old_index) as $msguid) {
                 if ($object = $this->folder->read_object($msguid, '*')) {
                     $this->_extended_insert($msguid, $object);
                 }
             }
             $this->_extended_insert(0, null);
 
             // delete invalid entries from local DB
             $del_index = array_diff($old_index, $this->index);
             if (!empty($del_index)) {
                 $quoted_ids = join(',', array_map(array($this->db, 'quote'), $del_index));
                 $this->db->query(
                     "DELETE FROM kolab_cache WHERE resource=? AND msguid IN ($quoted_ids)",
                     $this->resource_uri
                 );
             }
         }
 
         // remove lock
         $this->_sync_unlock();
 
         $this->synched = time();
     }
 
 
     /**
      * Read a single entry from cache or from IMAP directly
      *
      * @param string Related IMAP message UID
      * @param string Object type to read
      * @param string IMAP folder name the entry relates to
      * @param array  Hash array with object properties or null if not found
      */
     public function get($msguid, $type = null, $foldername = null)
     {
         // delegate to another cache instance
         if ($foldername && $foldername != $this->folder->name) {
             return kolab_storage::get_folder($foldername)->cache->get($msguid, $object);
         }
 
         // load object if not in memory
         if (!isset($this->objects[$msguid])) {
             if ($this->ready) {
                 $sql_result = $this->db->query(
                     "SELECT * FROM kolab_cache ".
                     "WHERE resource=? AND type=? AND msguid=?",
                     $this->resource_uri,
                     $type ?: $this->folder->type,
                     $msguid
                 );
 
                 if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
                     $this->objects[$msguid] = $this->_unserialize($sql_arr);
                 }
             }
 
             // fetch from IMAP if not present in cache
             if (empty($this->objects[$msguid])) {
                 $result = $this->_fetch(array($msguid), $type, $foldername);
                 $this->objects[$msguid] = $result[0];
             }
         }
 
         return $this->objects[$msguid];
     }
 
 
     /**
      * Insert/Update a cache entry
      *
      * @param string Related IMAP message UID
      * @param mixed  Hash array with object properties to save or false to delete the cache entry
      * @param string IMAP folder name the entry relates to
      */
     public function set($msguid, $object, $foldername = null)
     {
         if (!$msguid) {
             return;
         }
 
         // delegate to another cache instance
         if ($foldername && $foldername != $this->folder->name) {
             kolab_storage::get_folder($foldername)->cache->set($msguid, $object);
             return;
         }
 
         // remove old entry
         if ($this->ready) {
             $this->db->query("DELETE FROM kolab_cache WHERE resource=? AND msguid=? AND type<>?",
                 $this->resource_uri, $msguid, 'lock');
         }
 
         if ($object) {
             // insert new object data...
             $this->insert($msguid, $object);
         }
         else {
             // ...or set in-memory cache to false
             $this->objects[$msguid] = $object;
         }
     }
 
 
     /**
      * Insert a cache entry
      *
      * @param string Related IMAP message UID
      * @param mixed  Hash array with object properties to save or false to delete the cache entry
      */
     public function insert($msguid, $object)
     {
         // write to cache
         if ($this->ready) {
             $sql_data = $this->_serialize($object);
             $objtype = $object['_type'] ? $object['_type'] : $this->folder->type;
 
             $result = $this->db->query(
                 "INSERT INTO kolab_cache ".
                 " (resource, type, msguid, uid, created, changed, data, xml, dtstart, dtend, tags, words)".
                 " VALUES (?, ?, ?, ?, " . $this->db->now() . ", ?, ?, ?, ?, ?, ?, ?)",
                 $this->resource_uri,
                 $objtype,
                 $msguid,
                 $object['uid'],
                 $sql_data['changed'],
                 $sql_data['data'],
                 $sql_data['xml'],
                 $sql_data['dtstart'],
                 $sql_data['dtend'],
                 $sql_data['tags'],
                 $sql_data['words']
             );
 
             if (!$this->db->affected_rows($result)) {
                 rcube::raise_error(array(
                     'code' => 900, 'type' => 'php',
                     'message' => "Failed to write to kolab cache"
                 ), true);
             }
         }
 
         // keep a copy in memory for fast access
         $this->objects[$msguid] = $object;
         $this->uid2msg[$object['uid']] = $msguid;
     }
 
 
     /**
      * Move an existing cache entry to a new resource
      *
      * @param string Entry's IMAP message UID
      * @param string Entry's Object UID
      * @param string Target IMAP folder to move it to
      */
     public function move($msguid, $objuid, $target_folder)
     {
         $target = kolab_storage::get_folder($target_folder);
 
         // resolve new message UID in target folder
         if ($new_msguid = $target->cache->uid2msguid($objuid)) {
             $this->db->query(
                 "UPDATE kolab_cache SET resource=?, msguid=? ".
                 "WHERE resource=? AND msguid=? AND type<>?",
                 $target->get_resource_uri(),
                 $new_msguid,
                 $this->resource_uri,
                 $msguid,
                 'lock'
             );
         }
         else {
             // just clear cache entry
             $this->set($msguid, false);
         }
 
         unset($this->uid2msg[$uid]);
     }
 
 
     /**
      * Remove all objects from local cache
      */
     public function purge($type = null)
     {
         $result = $this->db->query(
             "DELETE FROM kolab_cache WHERE resource=?".
             ($type ? ' AND type=?' : ''),
             $this->resource_uri,
             $type
         );
         return $this->db->affected_rows($result);
     }
 
 
     /**
      * Select Kolab objects filtered by the given query
      *
      * @param array Pseudo-SQL query as list of filter parameter triplets
      *   triplet: array('<colname>', '<comparator>', '<value>')
      * @param boolean Set true to only return UIDs instead of complete objects
      * @return array List of Kolab data objects (each represented as hash array) or UIDs
      */
     public function select($query = array(), $uids = false)
     {
         $result = array();
 
         // read from local cache DB (assume it to be synchronized)
         if ($this->ready) {
             $sql_result = $this->db->query(
                 "SELECT " . ($uids ? 'msguid, uid' : '*') . " FROM kolab_cache ".
                 "WHERE resource=? " . $this->_sql_where($query),
                 $this->resource_uri
             );
 
             while ($sql_arr = $this->db->fetch_assoc($sql_result)) {
                 if ($uids) {
                     $this->uid2msg[$sql_arr['uid']] = $sql_arr['msguid'];
                     $result[] = $sql_arr['uid'];
                 }
                 else if ($object = $this->_unserialize($sql_arr)) {
                     $result[] = $object;
                 }
             }
         }
         else {
             // extract object type from query parameter
             $filter = $this->_query2assoc($query);
 
             // use 'list' for folder's default objects
             if ($filter['type'] == $this->type) {
                 $index = $this->index;
             }
             else {  // search by object type
                 $search = 'UNDELETED HEADER X-Kolab-Type ' . kolab_format::KTYPE_PREFIX . $filter['type'];
                 $index = $this->imap->search_once($this->folder->name, $search)->get();
             }
 
             // fetch all messages in $index from IMAP
             $result = $uids ? $this->_fetch_uids($index, $filter['type']) : $this->_fetch($index, $filter['type']);
 
             // TODO: post-filter result according to query
         }
 
         return $result;
     }
 
 
     /**
      * Get number of objects mathing the given query
      *
      * @param array  $query Pseudo-SQL query as list of filter parameter triplets
      * @return integer The number of objects of the given type
      */
     public function count($query = array())
     {
         $count = 0;
 
         // cache is in sync, we can count records in local DB
         if ($this->synched) {
             $sql_result = $this->db->query(
                 "SELECT COUNT(*) AS numrows FROM kolab_cache ".
                 "WHERE resource=? " . $this->_sql_where($query),
                 $this->resource_uri
             );
 
             $sql_arr = $this->db->fetch_assoc($sql_result);
             $count = intval($sql_arr['numrows']);
         }
         else {
             // search IMAP by object type
             $filter = $this->_query2assoc($query);
             $ctype  = kolab_format::KTYPE_PREFIX . $filter['type'];
             $index = $this->imap->search_once($this->folder->name, 'UNDELETED HEADER X-Kolab-Type ' . $ctype);
             $count = $index->count();
         }
 
         return $count;
     }
 
 
     /**
      * Helper method to compose a valid SQL query from pseudo filter triplets
      */
     private function _sql_where($query)
     {
         $sql_where = '';
         foreach ($query as $param) {
             if ($param[1] == '=' && is_array($param[2])) {
                 $qvalue = '(' . join(',', array_map(array($this->db, 'quote'), $param[2])) . ')';
                 $param[1] = 'IN';
             }
             else if ($param[1] == '~' || $param[1] == 'LIKE' || $param[1] == '!~' || $param[1] == '!LIKE') {
                 $not = ($param[1] == '!~' || $param[1] == '!LIKE') ? 'NOT ' : '';
                 $param[1] = $not . 'LIKE';
                 $qvalue = $this->db->quote('%'.preg_replace('/(^\^|\$$)/', ' ', $param[2]).'%');
             }
             else if ($param[0] == 'tags') {
                 $param[1] = 'LIKE';
                 $qvalue = $this->db->quote('% '.$param[2].' %');
             }
             else {
                 $qvalue = $this->db->quote($param[2]);
             }
 
             $sql_where .= sprintf(' AND %s %s %s',
                 $this->db->quote_identifier($param[0]),
                 $param[1],
                 $qvalue
             );
         }
 
         return $sql_where;
     }
 
     /**
      * Helper method to convert the given pseudo-query triplets into
      * an associative filter array with 'equals' values only
      */
     private function _query2assoc($query)
     {
         // extract object type from query parameter
         $filter = array();
         foreach ($query as $param) {
             if ($param[1] == '=')
                 $filter[$param[0]] = $param[2];
         }
         return $filter;
     }
 
     /**
      * Fetch messages from IMAP
      *
      * @param array  List of message UIDs to fetch
      * @param string Requested object type or * for all
      * @param string IMAP folder to read from
      * @return array List of parsed Kolab objects
      */
     private function _fetch($index, $type = null, $folder = null)
     {
         $results = array();
         foreach ((array)$index as $msguid) {
             if ($object = $this->folder->read_object($msguid, $type, $folder)) {
                 $results[] = $object;
                 $this->set($msguid, $object);
             }
         }
 
         return $results;
     }
 
 
     /**
      * Fetch object UIDs (aka message subjects) from IMAP
      *
      * @param array List of message UIDs to fetch
      * @param string Requested object type or * for all
      * @param string IMAP folder to read from
      * @return array List of parsed Kolab objects
      */
     private function _fetch_uids($index, $type = null)
     {
         if (!$type)
             $type = $this->folder->type;
 
         $results = array();
         foreach ((array)$this->imap->fetch_headers($this->folder->name, $index, false) as $msguid => $headers) {
             $object_type = kolab_format::mime2object_type($headers->others['x-kolab-type']);
 
             // check object type header and abort on mismatch
             if ($type != '*' && $object_type != $type)
                 return false;
 
             $uid = $headers->subject;
             $this->uid2msg[$uid] = $msguid;
             $results[] = $uid;
         }
 
         return $results;
     }
 
 
     /**
      * Helper method to convert the given Kolab object into a dataset to be written to cache
      */
     private function _serialize($object)
     {
         $bincols = array_flip($this->binary_cols);
         $sql_data = array('changed' => null, 'dtstart' => null, 'dtend' => null, 'xml' => '', 'tags' => '', 'words' => '');
         $objtype = $object['_type'] ? $object['_type'] : $this->folder->type;
 
         // set type specific values
         if ($objtype == 'event') {
             // database runs in server's timezone so using date() is what we want
             $sql_data['dtstart'] = date('Y-m-d H:i:s', is_object($object['start']) ? $object['start']->format('U') : $object['start']);
             $sql_data['dtend']   = date('Y-m-d H:i:s', is_object($object['end'])   ? $object['end']->format('U')   : $object['end']);
 
             // extend date range for recurring events
             if ($object['recurrence'] && $object['_formatobj']) {
                 $recurrence = new kolab_date_recurrence($object['_formatobj']);
                 $sql_data['dtend'] = date('Y-m-d 23:59:59', $recurrence->end() ?: strtotime('now +1 year'));
             }
         }
         else if ($objtype == 'task') {
             if ($object['start'])
                 $sql_data['dtstart'] = date('Y-m-d H:i:s', is_object($object['start']) ? $object['start']->format('U') : $object['start']);
             if ($object['due'])
                 $sql_data['dtend']   = date('Y-m-d H:i:s', is_object($object['due'])   ? $object['due']->format('U')   : $object['due']);
         }
 
         if ($object['changed']) {
             $sql_data['changed'] = date('Y-m-d H:i:s', is_object($object['changed']) ? $object['changed']->format('U') : $object['changed']);
         }
 
         if ($object['_formatobj']) {
             $sql_data['xml'] = preg_replace('!(</?[a-z0-9:-]+>)[\n\r\t\s]+!ms', '$1', (string)$object['_formatobj']->write());
             $sql_data['tags'] = ' ' . join(' ', $object['_formatobj']->get_tags()) . ' ';  // pad with spaces for strict/prefix search
             $sql_data['words'] = ' ' . join(' ', $object['_formatobj']->get_words()) . ' ';
         }
 
         // extract object data
         $data = array();
         foreach ($object as $key => $val) {
             if ($val === "" || $val === null) {
                 // skip empty properties
                 continue;
             }
             if (isset($bincols[$key])) {
                 $data[$key] = base64_encode($val);
             }
             else if ($key[0] != '_') {
                 $data[$key] = $val;
             }
             else if ($key == '_attachments') {
                 foreach ($val as $k => $att) {
                     unset($att['content'], $att['path']);
                     if ($att['id'])
                         $data[$key][$k] = $att;
                 }
             }
         }
 
         $sql_data['data'] = serialize($data);
         return $sql_data;
     }
 
     /**
      * Helper method to turn stored cache data into a valid storage object
      */
     private function _unserialize($sql_arr)
     {
         $object = unserialize($sql_arr['data']);
 
         // decode binary properties
         foreach ($this->binary_cols as $key) {
             if (!empty($object[$key]))
                 $object[$key] = base64_decode($object[$key]);
         }
 
         // add meta data
         $object['_type'] = $sql_arr['type'];
         $object['_msguid'] = $sql_arr['msguid'];
         $object['_mailbox'] = $this->folder->name;
         $object['_formatobj'] = kolab_format::factory($sql_arr['type'], 3.0, $sql_arr['xml']);
 
         return $object;
     }
 
     /**
      * Write records into cache using extended inserts to reduce the number of queries to be executed
      *
      * @param int  Message UID. Set 0 to commit buffered inserts
      * @param array Kolab object to cache
      */
     private function _extended_insert($msguid, $object)
     {
         static $buffer = '';
 
         $line = '';
         if ($object) {
             $sql_data = $this->_serialize($object);
             $objtype = $object['_type'] ? $object['_type'] : $this->folder->type;
 
             $values = array(
                 $this->db->quote($this->resource_uri),
                 $this->db->quote($objtype),
                 $this->db->quote($msguid),
                 $this->db->quote($object['uid']),
                 $this->db->now(),
                 $this->db->quote($sql_data['changed']),
                 $this->db->quote($sql_data['data']),
                 $this->db->quote($sql_data['xml']),
                 $this->db->quote($sql_data['dtstart']),
                 $this->db->quote($sql_data['dtend']),
                 $this->db->quote($sql_data['tags']),
                 $this->db->quote($sql_data['words']),
             );
             $line = '(' . join(',', $values) . ')';
         }
 
         if ($buffer && (!$msguid || (strlen($buffer) + strlen($line) > $this->max_sql_packet))) {
             $result = $this->db->query(
                 "INSERT INTO kolab_cache ".
                 " (resource, type, msguid, uid, created, changed, data, xml, dtstart, dtend, tags, words)".
                 " VALUES $buffer"
             );
             if (!$this->db->affected_rows($result)) {
                 rcube::raise_error(array(
                     'code' => 900, 'type' => 'php',
                     'message' => "Failed to write to kolab cache"
                 ), true);
             }
 
             $buffer = '';
         }
 
         $buffer .= ($buffer ? ',' : '') . $line;
     }
 
     /**
      * Check lock record for this folder and wait if locked or set lock
      */
     private function _sync_lock()
     {
         if (!$this->ready)
             return;
 
         $sql_arr = $this->db->fetch_assoc($this->db->query(
             "SELECT msguid AS locked, ".$this->db->unixtimestamp('created')." AS created FROM kolab_cache ".
             "WHERE resource=? AND type=?",
             $this->resource_uri,
             'lock'
         ));
 
         // abort if database is not set-up
         if ($this->db->is_error()) {
             $this->ready = false;
             return;
         }
 
         $this->synclock = true;
 
         // create lock record if not exists
         if (!$sql_arr) {
             $this->db->query(
                 "INSERT INTO kolab_cache (resource, type, msguid, created, uid, data, xml)".
                 " VALUES (?, ?, 1, ?, '', '', '')",
                 $this->resource_uri,
                 'lock',
                 date('Y-m-d H:i:s')
             );
         }
         // wait if locked (expire locks after 10 minutes)
         else if (intval($sql_arr['locked']) > 0 && (time() - $sql_arr['created']) < 600) {
             usleep(500000);
             return $this->_sync_lock();
         }
         // set lock
         else {
             $this->db->query(
                 "UPDATE kolab_cache SET msguid=1, created=? ".
                 "WHERE resource=? AND type=?",
                 date('Y-m-d H:i:s'),
                 $this->resource_uri,
                 'lock'
             );
         }
     }
 
     /**
      * Remove lock for this folder
      */
     public function _sync_unlock()
     {
         if (!$this->ready || !$this->synclock)
             return;
 
         $this->db->query(
             "UPDATE kolab_cache SET msguid=0 ".
             "WHERE resource=? AND type=?",
             $this->resource_uri,
             'lock'
         );
 
         $this->synclock = false;
     }
 
     /**
      * Resolve an object UID into an IMAP message UID
      *
      * @param string  Kolab object UID
      * @param boolean Include deleted objects
      * @return int The resolved IMAP message UID
      */
     public function uid2msguid($uid, $deleted = false)
     {
         if (!isset($this->uid2msg[$uid])) {
             // use IMAP SEARCH to get the right message
-            $index = $this->imap->search_once($this->folder->name, ($deleted ? '' : 'UNDELETED ') . 'HEADER SUBJECT "' . $uid. '"');
+            $index = $this->imap->search_once($this->folder->name, ($deleted ? '' : 'UNDELETED ') .
+				'HEADER SUBJECT ' . rcube_imap_generic::escape($uid));
             $results = $index->get();
             $this->uid2msg[$uid] = $results[0];
         }
 
         return $this->uid2msg[$uid];
     }
 
 }