diff --git a/composer.json b/composer.json
--- a/composer.json
+++ b/composer.json
@@ -2,12 +2,7 @@
 	"name": "kolab/free-busy",
 	"description": "Kolab Free/Busy Service",
 	"license": "AGPL-3.0",
-	"version": "1.1.0",
 	"repositories": [
-		{
-			"type": "pear",
-			"url": "http://pear.php.net/"
-		},
 		{
 			"type": "vcs",
 			"url": "https://git.kolab.org/diffusion/PNL/php-net_ldap.git"
@@ -15,13 +10,13 @@
 	],
 	"require": {
 		"php": ">=5.3.3",
-		"monolog/monolog": "1.2.*",
-		"desarrolla2/cache":  "dev-master",
-		"sabre/vobject": "~3.3.3"
+		"monolog/monolog": "~1.2",
+		"sabre/vobject": "~3.3.3",
+		"garethp/php-ews": "~0.10.1"
 	},
 	"require-dev": {
-		"pear-pear.php.net/net_ldap2": ">=2.0.12",
-		"kolab/Net_LDAP3": "dev-master"
+		"pear/net_ldap2": "~2.2.0",
+		"kolab/net_ldap3": "~1.1.3"
 	},
-	"minimum-stability": "dev"
+	"minimum-stability": "stable"
 }
diff --git a/composer.json-dist b/composer.json-dist
--- a/composer.json-dist
+++ b/composer.json-dist
@@ -2,7 +2,6 @@
 	"name": "kolab/free-busy",
 	"description": "Kolab Free/Busy Service",
 	"license": "AGPL-3.0",
-	"version": "1.1.0",
 	"autoload": {
 		"psr-0": {
 			"": "/usr/share/pear/"
diff --git a/lib/Kolab/Config.php b/lib/Kolab/Config.php
--- a/lib/Kolab/Config.php
+++ b/lib/Kolab/Config.php
@@ -175,7 +175,9 @@
         }
         else if (is_array($config)) {
             $pkey = rtrim($prefix, '.');
-            $this->data[$pkey] = is_array($this->data[$pkey]) ? array_replace_recursive((array)$this->data[$pkey], $config) : $config;
+            $this->data[$pkey] = isset($this->data[$pkey]) && is_array($this->data[$pkey])
+                ? array_replace_recursive((array)$this->data[$pkey], $config)
+                : $config;
         }
 
         foreach ((array)$config as $key => $val) {
@@ -216,7 +218,7 @@
      */
     public function __get($name)
     {
-        return $this->data[$name];
+        return isset($this->data[$name]) ? $this->data[$name] : null;
     }
 
     /**
diff --git a/lib/Kolab/FreeBusy/Directory.php b/lib/Kolab/FreeBusy/Directory.php
--- a/lib/Kolab/FreeBusy/Directory.php
+++ b/lib/Kolab/FreeBusy/Directory.php
@@ -30,91 +30,108 @@
  */
 abstract class Directory
 {
-	protected $config;
-
-	/**
-	 * Factory method creating an instace of Directory according to config
-	 *
-	 * @param array Hash array with config
-	 */
-	public static function factory($config)
-	{
-		switch (strtolower($config['type'])) {
-			case 'ldap':
-				return new DirectoryLDAP($config);
-
-			case 'static':
-			case 'external':
-				return new DirectoryStatic($config);
-
-			default:
-				Logger::get('directory')->addError("Invalid directory type '" . $config['type'] . "'!");
-		}
-
-		return null;
-	}
-
-	/**
-	 * Resolve the given username to a Entity object
-	 *
-	 * @param string Username/Email to resolve
-	 * @return object Entity if found, otherwise False
-	 */
-	abstract public function resolve($user);
-
-	/**
-	 * Retrieve free/busy data for the given user.
-	 *
-	 * @param string Username or email to resolve
-	 * @param boolean Get extemded free-busy if possible
-	 * @return string VCalendar container if found, False otherwise
-	 */
-	public function getFreeBusyData($user, $extended = false)
-	{
-		// resolve user record first
-		if ($user = $this->resolve($user)) {
-			$fbsource = $this->config['fbsource'];
-			if ($source = Source::Factory($fbsource, $this->config)) {
-				// forward request to Source instance
-				if ($data = $source->getFreeBusyData($this->postprocessAttrib($user), $extended)) {
-					// send data through the according format converter
-					$converter = Format::factory($this->config['format']);
-					$data = $converter->toVCalendar($data);
-
-					// cache the generated data
-					if ($data && $this->config['cacheto'] && !$source->isCached()) {
-						$path = preg_replace_callback(
-							'/%\{?([a-z0-9]+)\}?/',
-							function($m) use ($user) { return $user[$m[1]]; },
-							$this->config['cacheto']
-						);
-
-						if (!@file_put_contents($path, $data, LOCK_EX)) {
-							Logger::get('directory')->addError("Failed to write to cache file '" . $path . "'!");
-						}
-					}
-				}
-
-				return $data;
-			}
-		}
-
-		return false;
-	}
-
-	/**
-	 * Modify attribute values according to config
-	 */
-	protected function postprocessAttrib($attrib)
-	{
-		if (!empty($this->config['lc_attributes'])) {
-			foreach (Config::convert($this->config['lc_attributes'], Config::ARR) as $key) {
-				if (!empty($attrib[$key]))
-					$attrib[$key] = strtolower($attrib[$key]);
-			}
-		}
-
-		return $attrib;
-	}
-
-}
\ No newline at end of file
+    protected $config;
+
+    /**
+     * Factory method creating an instace of Directory according to config
+     *
+     * @param array Hash array with config
+     */
+    public static function factory($config)
+    {
+        switch (strtolower($config['type'])) {
+        case 'ldap':
+            return new DirectoryLDAP($config);
+
+        case 'static':
+        case 'external':
+            return new DirectoryStatic($config);
+
+        default:
+            Logger::get('directory')->addError("Invalid directory type '" . $config['type'] . "'!");
+        }
+
+        return null;
+    }
+
+    /**
+     * Resolve the given username to a Entity object
+     *
+     * @param string Username/Email to resolve
+     * @return object Entity if found, otherwise False
+     */
+    abstract public function resolve($user);
+
+    /**
+     * Retrieve free/busy data for the given user.
+     *
+     * @param string Username or email to resolve
+     * @param boolean Get extemded free-busy if possible
+     * @return string VCalendar container if found, False otherwise
+     */
+    public function getFreeBusyData($user, $extended = false)
+    {
+        $logger = Logger::get('directory');
+
+        // resolve user record first
+        if ($user = $this->resolve($user)) {
+            $fbsource = $this->config['fbsource'];
+            if ($source = Source::Factory($fbsource, $this->config)) {
+                $user = $this->postprocessAttrib($user);
+
+                // Find the cached data
+                if (!empty($this->config['cacheto'])) {
+                    $path = preg_replace_callback(
+                        '/%\{?([a-z0-9]+)\}?/',
+                        function($m) use ($user) { return $user[$m[1]]; },
+                        $this->config['cacheto']
+                    );
+
+                    // check for cached data
+                    if (file_exists($path)) {
+                        if (empty($this->config['expires']) || filemtime($path) + Utils::getOffsetSec($this->config['expires']) >= time()) {
+                            $logger->addInfo("Deliver cached data from {$path}");
+                            return file_get_contents($path);
+                        }
+                    }
+                }
+
+                // forward request to Source instance
+                if ($data = $source->getFreeBusyData($user, $extended)) {
+                    // send data through the according format converter
+                    $converter = Format::factory($this->config['format']);
+                    $data = $converter->toVCalendar($data);
+
+                    // cache the generated data
+                    if ($data && !empty($path)) {
+                        if (!file_put_contents($path, $data, LOCK_EX)) {
+                            $logger->addError("Failed to write to cache in {$path}");
+                        } else {
+                            $logger->addInfo("Cached data in {$path}");
+                        }
+                    }
+                }
+
+                return $data;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Modify attribute values according to config
+     */
+    protected function postprocessAttrib($attrib)
+    {
+        if (!empty($this->config['lc_attributes'])) {
+            foreach (Config::convert($this->config['lc_attributes'], Config::ARR) as $key) {
+                if (!empty($attrib[$key])) {
+                    $attrib[$key] = strtolower($attrib[$key]);
+                }
+            }
+        }
+
+        return $attrib;
+    }
+}
diff --git a/lib/Kolab/FreeBusy/DirectoryStatic.php b/lib/Kolab/FreeBusy/DirectoryStatic.php
--- a/lib/Kolab/FreeBusy/DirectoryStatic.php
+++ b/lib/Kolab/FreeBusy/DirectoryStatic.php
@@ -31,29 +31,28 @@
  */
 class DirectoryStatic extends Directory
 {
-	/**
-	 * Default constructor loading directory configuration
-	 */
-	public function __construct($config)
-	{
-		$this->config = $config;
-	}
-
-	/**
-	 * @see Directory::resolve()
-	 */
-	public function resolve($user)
-	{
-		$result = array('s' => $user);
-
-		// check if user matches the filter property (if configured)
-		if (!empty($this->config['filter'])) {
-			if (!preg_match('!'.$this->config['filter'].'!i', $user))
-			 	$result = false;
-		}
-
-		return $result;
-	}
-
+    /**
+     * Default constructor loading directory configuration
+     */
+    public function __construct($config)
+    {
+        $this->config = $config;
+    }
+
+    /**
+     * @see Directory::resolve()
+     */
+    public function resolve($user)
+    {
+        $result = array('s' => $user);
+
+        // check if user matches the filter property (if configured)
+        if (!empty($this->config['filter'])) {
+            if (!preg_match('!'.$this->config['filter'].'!i', $user)) {
+                $result = false;
+            }
+        }
+
+        return $result;
+    }
 }
-
diff --git a/lib/Kolab/FreeBusy/Source.php b/lib/Kolab/FreeBusy/Source.php
--- a/lib/Kolab/FreeBusy/Source.php
+++ b/lib/Kolab/FreeBusy/Source.php
@@ -29,7 +29,6 @@
 abstract class Source
 {
 	protected $config = array();
-	protected $cached = false;
 
 	/**
 	 * Factory method creating an instace of Source according to config
@@ -51,6 +50,7 @@
 			case 'fbd':
 			case 'fbdaemon': return new SourceFBDaemon($config + $conf);
 			case 'aggregate': return new SourceAggregator($config + $conf);
+			case 'ews': return new SourceEWS($config + $conf);
 		}
 
 		Logger::get('source')->addError("Invalid source configuration: " . $url);
@@ -68,7 +68,7 @@
 	/**
 	 * Retrieve free/busy data for the given user
 	 *
-	 * @param array Hash array with user attributes
+	 * @param false|string vCalendar (ICS) file output, or False on error
 	 */
 	abstract public function getFreeBusyData($user, $extended);
 
@@ -81,7 +81,7 @@
 		foreach ($this->config as $k => $val) {
 			if (is_string($val) && strpos($val, '%') !== false) {
 				$val = preg_replace_callback(
-					'/%\{?([a-z0-9]+)\}?/',
+					'/%\{?([a-z]{1}[a-z0-9]*)\}?/',
 					function($m) use ($k, $user) {
 						$enc = $k == 'url' || $k == 'query' || $k == 'fbsource';
 						return $enc ? urlencode($user[$m[1]]) : $user[$m[1]];
@@ -94,30 +94,4 @@
 
 		return $config;
 	}
-
-	/**
-	 * Helper method to check if a cached file exists and is still valid
-	 *
-	 * @param array Hash array with (replaced) config properties
-	 * @return string Cached free-busy data or false if cache file doesn't exist or is expired
-	 */
-	protected function getCached($config)
-	{
-		if ($config['cacheto'] && file_exists($config['cacheto'])) {
-			if (empty($config['expires']) || filemtime($config['cacheto']) + Utils::getOffsetSec($config['expires']) >= time()) {
-				$this->cached = true;
-				return file_get_contents($config['cacheto']);
-			}
-		}
-
-		return false;
-	}
-
-	/**
-	 * Return the value of the 'cached' flag
-	 */
-	public function isCached()
-	{
-		return $this->cached;
-	}
 }
diff --git a/lib/Kolab/FreeBusy/SourceAggregator.php b/lib/Kolab/FreeBusy/SourceAggregator.php
--- a/lib/Kolab/FreeBusy/SourceAggregator.php
+++ b/lib/Kolab/FreeBusy/SourceAggregator.php
@@ -40,7 +40,7 @@
 	public function getFreeBusyData($user, $extended)
 	{
 		$log = Logger::get('aggregate', intval($this->config['loglevel']));
-		# $config = $this->getUserConfig($user);
+		// $config = $this->getUserConfig($user);
 
 		$attr = str_replace('%', '', strval($this->config['path'] ?: $this->config['host']));
 		if (!empty($user[$attr])) {
diff --git a/lib/Kolab/FreeBusy/SourceEWS.php b/lib/Kolab/FreeBusy/SourceEWS.php
new file mode 100644
--- /dev/null
+++ b/lib/Kolab/FreeBusy/SourceEWS.php
@@ -0,0 +1,202 @@
+<?php
+
+/**
+ * This file is part of the Kolab Server Free/Busy Service
+ *
+ * @author Aleksander Machniak <machniak@kolabsys.com>
+ *
+ * Copyright (C) 2013-2021, Apheleia IT AG <contact@apheleia.ch>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Kolab\FreeBusy;
+
+use garethp\ews\API;
+use garethp\ews\API\Exception;
+
+/**
+ * Implementation of a Free/Busy data source reading from an EWS server
+ */
+class SourceEWS extends Source
+{
+    /**
+     * @see Source::getFreeBusyData()
+     */
+    public function getFreeBusyData($user, $extended)
+    {
+        $config = $this->getUserConfig($user);
+        $user = is_array($user) ? $user['s'] : $user;
+
+        // Get start and end date for the request
+        list($start, $end) = $this->getPeriod();
+
+        // Fetch the availability info from the EWS server
+        $data = $this->fetchData($user, $start, $end, $config);
+
+        if ($data === false) {
+            return false;
+        }
+
+        // Process the data (convert to ics)
+        foreach ($data as $idx => $event) {
+            // Map the busy-type property
+            switch ($event->getBusyType()) {
+            case 'Free':
+                $fbtype = 'FREE';
+                break;
+
+            case 'Tentative':
+                $fbtype = 'BUSY-TENTATIVE';
+                break;
+
+            case 'Busy':
+            // case 'OOF':
+            // case 'NoData':
+            default:
+                $fbtype = 'BUSY';
+                break;
+            }
+
+            $startTime = new \DateTime($event->getStartTime(), new \DateTimeZone('UTC'));
+            $endTime = new \DateTime($event->getEndTime(), new \DateTimeZone('UTC'));
+
+            $data[$idx] = sprintf(
+                "FREEBUSY;FBTYPE=%s:%s/%s",
+                $fbtype,
+                $startTime->format('Ymd\THis\Z'),
+                $endTime->format('Ymd\THis\Z'),
+            );
+        }
+
+        return sprintf(
+            "BEGIN:VCALENDAR\n"
+            . "PRODID:%s\n"
+            . "VERSION:2.0\n"
+            . "METHOD:PUBLISH\n"
+            . "BEGIN:VFREEBUSY\n"
+            . "ORGANIZER:mailto:%s\n"
+            . "UID:%s\n"
+            . "DTSTAMP:%s\n"
+            . "DTSTART:%s\n"
+            . "DTEND:%s\n"
+            . "%s\n"
+            . "END:VFREEBUSY\n"
+            . "END:VCALENDAR\n",
+            Utils::PRODID,
+            $user,
+            \date('YmdHi') . '-' . \substr(\md5($user), 0, 16),
+            $start->format('Ymd\THis\Z'),
+            $start->format('Ymd\THis\Z'),
+            $end->format('Ymd\THis\Z'),
+            implode("\n", $data)
+        );
+    }
+
+    /**
+     * Fetches the user availability data from the EWS server
+     */
+    private function fetchData($user, $startdate, $enddate, $config)
+    {
+        $logger = Logger::get('ews');
+
+        $logger->addDebug(sprintf("Fetching data from %s for %s...", $config['host'], $user));
+
+        try {
+            // Create and build the client
+            $api = API::withUsernameAndPassword(
+                $config['host'],
+                urldecode($config['user']),
+                urldecode($config['pass']),
+                array(
+                    // return date-time in UTC
+                    'timezone' => 'UTC',
+                    // act as the requested user
+                    'impersonation' => $user
+                )
+            );
+
+            $calendar = $api->getCalendar();
+
+            // This is using the EWS's GetUserAvailability API
+            $options = array();
+/*
+            $options = array(
+                'FreeBusyViewOptions' => array(
+                    'MergedFreeBusyIntervalInMinutes' => 15 // default: 30
+                )
+            );
+*/
+            $availability = $calendar->getAvailabilityFor($startdate, $enddate, array($user), $options);
+
+            // Check response status
+            $responseMessage = $availability->getFreeBusyResponseArray()->FreeBusyResponse->getResponseMessage();
+            if ($responseMessage->getResponseClass() === 'Error') {
+                throw new Exception\ExchangeException($responseMessage);
+            }
+
+            $items = $availability->getFreeBusyResponseArray()->FreeBusyResponse->getFreeBusyView()->getCalendarEventArray();
+
+            if ($items && $items->CalendarEvent) {
+                $logger->addDebug(sprintf("Found %d events", count($items->CalendarEvent)));
+                return $items->CalendarEvent;
+            }
+
+            $logger->addDebug("Found 0 events");
+            return array();
+        } catch (Exception\UnauthorizedException $e) {
+            $logger->addError("EWS access unauthorized");
+        } catch (Exception\ServiceUnavailableException $e) {
+            $logger->addError("EWS service unavailable");
+        } catch (Exception\NoResponseReturnedException $e) {
+            $logger->addError("EWS no response");
+        } catch (Exception\AutodiscoverFailed $e) {
+            $logger->addError("EWS autodiscovery failed");
+        } catch (\Exception $e) {
+            $logger->addError($e->getMessage() ?: "EWS unknown error");
+        }
+
+        return false;
+    }
+
+    /**
+     * Get request period start and end
+     */
+    private function getPeriod()
+    {
+        // use date from HTTP query
+        if (!empty($_GET['dtstart']) &&
+            ($dtstart = \filter_input(INPUT_GET, 'dtstart', FILTER_SANITIZE_STRING))
+        ) {
+            try {
+                $start = new \DateTime($dtstart, new \DateTimezone('UTC'));
+            } catch (Exception $e) {
+                // ignore
+            }
+        }
+
+        if (empty($start)) {
+            $start = new \DateTime('now', new \DateTimeZone('UTC'));
+        }
+
+        // Set the period to 7 days in the past and 42-7 days in the future
+        // Note: 42 days is max. supported period on EWS
+
+        $start->sub(new \DateInterval('P7D'));
+        $end = clone $start;
+        $end->add(new \DateInterval('P42D'));
+
+        return array($start, $end);
+    }
+}
diff --git a/lib/Kolab/FreeBusy/SourceFBDaemon.php b/lib/Kolab/FreeBusy/SourceFBDaemon.php
--- a/lib/Kolab/FreeBusy/SourceFBDaemon.php
+++ b/lib/Kolab/FreeBusy/SourceFBDaemon.php
@@ -42,23 +42,6 @@
 		// log this...
 		$log->addInfo("Fetching data for ", $config);
 
-		// caching is enabled
-		if (!empty($config['cacheto'])) {
-			// check for cached data
-			if ($cached = $this->getCached($config)) {
-				$log->addInfo("Deliver cached data from " . $config['cacheto']);
-				return $cached;
-			}
-			// touch cache file to avoid multiple requests generating the same data
-			if (file_exists($config['cacheto'])) {
-				touch($config['cacheto']);
-			}
-			else {
-				file_put_contents($config['cacheto'], Utils::dummyVFreebusy($user['mail']));
-				$tempfile = $config['cacheto'];
-			}
-		}
-
 		// compose command for freebusyd
 		if (!empty($config['folder'])) {
 			$cmd = 'FOLDER';
@@ -128,10 +111,6 @@
 			}
 			return $fbdata;
 		}
-		// remove (temporary) cache file again
-		else if ($tempfile) {
-			unlink($tempfile);
-		}
 
 		// not found
 		return false;
diff --git a/lib/Kolab/FreeBusy/SourceIMAP.php b/lib/Kolab/FreeBusy/SourceIMAP.php
--- a/lib/Kolab/FreeBusy/SourceIMAP.php
+++ b/lib/Kolab/FreeBusy/SourceIMAP.php
@@ -79,23 +79,6 @@
 		// log this...
 		$log->addInfo("Fetching data for ", $config);
 
-		// caching is enabled
-		if (!empty($config['cacheto'])) {
-			// check for cached data
-			if ($cached = $this->getCached($config)) {
-				$log->addInfo("Deliver cached data from " . $config['cacheto']);
-				return $cached;
-			}
-			// touch cache file to avoid multiple requests generating the same data
-			if (file_exists($config['cacheto'])) {
-				touch($config['cacheto']);
-			}
-			else {
-				file_put_contents($config['cacheto'], Utils::dummyVFreebusy($user['mail']));
-				$tempfile = $config['cacheto'];
-			}
-		}
-
 		// compose a list of user email addresses
 		$user_email = array();
 		foreach (Config::convert($this->config['mail_attributes'], Config::ARR) as $key) {
@@ -258,10 +241,6 @@
 			// serialize to VCALENDAR format
 			return $freebusy->serialize();
 		}
-		// remove (temporary) cache file again
-		else if ($tempfile) {
-			unlink($tempfile);
-		}
 
 		return false;
 	}
diff --git a/lib/Kolab/FreeBusy/Utils.php b/lib/Kolab/FreeBusy/Utils.php
--- a/lib/Kolab/FreeBusy/Utils.php
+++ b/lib/Kolab/FreeBusy/Utils.php
@@ -249,7 +249,7 @@
 			}
 		}
 
-		// Should probably be a setting. For now, do 8 weeks in the past
+		// Should probably be a setting. For now, do 16 weeks into the future
 		return new \DateTime('now + 16 weeks 00:00:00', new \DateTimezone('UTC'));
 	}
 
diff --git a/public_html/index.php b/public_html/index.php
--- a/public_html/index.php
+++ b/public_html/index.php
@@ -50,79 +50,77 @@
 // load config
 $config = Config::get_instance(KOLAB_FREEBUSY_ROOT . '/config');
 if ($config->valid()) {
-	// check for trusted IP first
-	$remote_ip = Utils::remoteIP();
-	$trusted_ip = $config->trustednetworks ? Utils::checkIPRange($remote_ip, $config->get('trustednetworks.allow', array(), Config::ARR)) : false;
-
-	$log = Logger::get('web');
-
-	$uri = $_SERVER['REDIRECT_URL'];
-
-	// we're not always redirected here
-	if (empty($uri)) {
-		$uri = $_SERVER['REQUEST_URI'];
-		$log->addDebug('Request (direct): ' . $uri, array('ip' => $remote_ip, 'trusted' => $trusted_ip));
-	} else {
-		$log->addDebug('Request (redirect): ' . $uri, array('ip' => $remote_ip, 'trusted' => $trusted_ip));
-	}
-
-	list($uri, $args) = explode('?', $uri);
-
-	// check HTTP authentication
-	if (!$trusted_ip && $config->httpauth) {
-		$_SERVER['FREEBUSY_URI'] = urldecode(rtrim($uri, '/'));
-
-		if (!HTTPAuth::check($config->httpauth)) {
-			$log->addDebug("Abort with 401 Unauthorized");
-			header('WWW-Authenticate: Basic realm="Kolab Free/Busy Service"');
-			header($_SERVER['SERVER_PROTOCOL'] . " 401 Unauthorized", true);
-			exit;
-		}
-	}
-
-	#header('Content-type: text/calendar; charset=utf-8', true);
-	header('Content-type: text/plain; charset=utf-8', true);
-
-	// analyse request
-	$user     = $_SERVER['FREEBUSY_USER'];
-	$extended = !empty($_SERVER['FREEBUSY_EXTENDED']);
-
-	if (!$user) {
-		$url  = array_filter(explode('/', $uri));
-		$user = strtolower(array_pop($url));
-
-		// remove file extension
-		if (preg_match('/^(.+)\.([ipx]fb)$/i', $user, $m)) {
-			$user     = urldecode($m[1]);
-			$extended = $m[2] == 'xfb';
-		}
-	}
-
-	// iterate over directories
-	foreach ($config->directory as $key => $dirconfig) {
-		$log->addDebug("Trying directory $key", $dirconfig);
-
-		$directory = Directory::factory($dirconfig);
-		if ($directory && ($fbdata = $directory->getFreeBusyData($user, $extended))) {
-			$log->addInfo("Found valid data for user $user in directory $key");
-			echo $fbdata;
-			exit;
-		}
-	}
-
-	// return 404 if request was sent from a trusted IP
-	if ($trusted_ip) {
-		$log->addDebug("Returning '404 Not Found' for user $user");
-		header($_SERVER['SERVER_PROTOCOL'] . " 404 Not found", true);
-	}
-	else {
-		$log->addInfo("Returning empty Free/Busy list for user $user");
-
-		// Return an apparent empty Free/Busy list.
-		print Utils::dummyVFreebusy($user);
-	}
+    // check for trusted IP first
+    $remote_ip = Utils::remoteIP();
+    $trusted_ip = $config->trustednetworks ? Utils::checkIPRange($remote_ip, $config->get('trustednetworks.allow', array(), Config::ARR)) : false;
+
+    $log = Logger::get('web');
+
+    $uri = isset($_SERVER['REDIRECT_URL']) ? $_SERVER['REDIRECT_URL'] : '';
+
+    // we're not always redirected here
+    if (empty($uri)) {
+        $uri = $_SERVER['REQUEST_URI'];
+        $log->addDebug('Request (direct): ' . $uri, array('ip' => $remote_ip, 'trusted' => $trusted_ip));
+    } else {
+        $log->addDebug('Request (redirect): ' . $uri, array('ip' => $remote_ip, 'trusted' => $trusted_ip));
+    }
+
+    list($uri, ) = explode('?', $uri);
+
+    // check HTTP authentication
+    if (!$trusted_ip && $config->httpauth) {
+        $_SERVER['FREEBUSY_URI'] = urldecode(rtrim($uri, '/'));
+
+        if (!HTTPAuth::check($config->httpauth)) {
+            $log->addDebug("Abort with 401 Unauthorized");
+            header('WWW-Authenticate: Basic realm="Kolab Free/Busy Service"');
+            header($_SERVER['SERVER_PROTOCOL'] . " 401 Unauthorized", true);
+            exit;
+        }
+    }
+
+    //header('Content-type: text/calendar; charset=utf-8', true);
+    header('Content-type: text/plain; charset=utf-8', true);
+
+    // analyse request
+    $user     = isset($_SERVER['FREEBUSY_USER']) ? $_SERVER['FREEBUSY_USER'] : null;
+    $extended = !empty($_SERVER['FREEBUSY_EXTENDED']);
+
+    if (!$user) {
+        $url  = array_filter(explode('/', $uri));
+        $user = strtolower(array_pop($url));
+
+        // remove file extension
+        if (preg_match('/^(.+)\.([ipx]fb)$/i', $user, $m)) {
+            $user     = urldecode($m[1]);
+            $extended = $m[2] == 'xfb';
+        }
+    }
+
+    // iterate over directories
+    foreach ($config->directory as $key => $dirconfig) {
+        $log->addDebug("Trying directory $key", $dirconfig);
+
+        $directory = Directory::factory($dirconfig);
+        if ($directory && ($fbdata = $directory->getFreeBusyData($user, $extended))) {
+            $log->addInfo("Found valid data for user $user in directory $key");
+            echo $fbdata;
+            exit;
+        }
+    }
+
+    // return 404 if request was sent from a trusted IP
+    if ($trusted_ip) {
+        $log->addDebug("Returning '404 Not Found' for user $user");
+        header($_SERVER['SERVER_PROTOCOL'] . " 404 Not found", true);
+    } else {
+        $log->addInfo("Returning empty Free/Busy list for user $user");
+
+        // Return an apparent empty Free/Busy list.
+        print Utils::dummyVFreebusy($user);
+    }
 }
 
 // exit with error
 # header($_SERVER['SERVER_PROTOCOL'] . " 500 Internal Server Error", true);
-