upgrade to sabre32

70 files changed, 3298 insertions, 1980 deletions

diff --git a/vendor/sabre/dav/lib/CalDAV/Backend/BackendInterface.php b/vendor/sabre/dav/lib/CalDAV/Backend/BackendInterface.php
index 7513fb60d..bd8ee7602 100644
--- a/vendor/sabre/dav/lib/CalDAV/Backend/BackendInterface.php
+++ b/vendor/sabre/dav/lib/CalDAV/Backend/BackendInterface.php
@@ -44,10 +44,12 @@ interface BackendInterface {
      * If the creation was a success, an id must be returned that can be used to
      * reference this calendar in other methods, such as updateCalendar.
      *
+     * The id can be any type, including ints, strings, objects or array.
+     *
      * @param string $principalUri
      * @param string $calendarUri
      * @param array $properties
-     * @return void
+     * @return mixed
      */
     function createCalendar($principalUri, $calendarUri, array $properties);
 
@@ -63,7 +65,7 @@ interface BackendInterface {
      *
      * Read the PropPatch documentation for more info and examples.
      *
-     * @param string $path
+     * @param mixed $calendarId
      * @param \Sabre\DAV\PropPatch $propPatch
      * @return void
      */
diff --git a/vendor/sabre/dav/lib/CalDAV/Backend/NotificationSupport.php b/vendor/sabre/dav/lib/CalDAV/Backend/NotificationSupport.php
index 19b9b22a7..9c00a89ef 100644
--- a/vendor/sabre/dav/lib/CalDAV/Backend/NotificationSupport.php
+++ b/vendor/sabre/dav/lib/CalDAV/Backend/NotificationSupport.php
@@ -43,4 +43,19 @@ interface NotificationSupport extends BackendInterface {
      */
     function deleteNotification($principalUri, NotificationInterface $notification);
 
+    /**
+     * This method is called when a user replied to a request to share.
+     *
+     * If the user chose to accept the share, this method should return the
+     * newly created calendar url.
+     *
+     * @param string href The sharee who is replying (often a mailto: address)
+     * @param int status One of the SharingPlugin::STATUS_* constants
+     * @param string $calendarUri The url to the calendar thats being shared
+     * @param string $inReplyTo The unique id this message is a response to
+     * @param string $summary A description of the reply
+     * @return null|string
+     */
+    function shareReply($href, $status, $calendarUri, $inReplyTo, $summary = null);
+
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Backend/PDO.php b/vendor/sabre/dav/lib/CalDAV/Backend/PDO.php
index 76b69dc6e..b1c013d62 100644
--- a/vendor/sabre/dav/lib/CalDAV/Backend/PDO.php
+++ b/vendor/sabre/dav/lib/CalDAV/Backend/PDO.php
@@ -2,10 +2,11 @@
 
 namespace Sabre\CalDAV\Backend;
 
-use Sabre\VObject;
 use Sabre\CalDAV;
 use Sabre\DAV;
 use Sabre\DAV\Exception\Forbidden;
+use Sabre\VObject;
+use Sabre\DAV\Xml\Element\Sharee;
 
 /**
  * PDO CalDAV backend
@@ -17,7 +18,12 @@ use Sabre\DAV\Exception\Forbidden;
  * @author Evert Pot (http://evertpot.com/)
  * @license http://sabre.io/license/ Modified BSD License
  */
-class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, SchedulingSupport {
+class PDO extends AbstractBackend
+    implements
+        SyncSupport,
+        SubscriptionSupport,
+        SchedulingSupport,
+        SharingSupport {
 
     /**
      * We need to specify a max date, because we need to stop *somewhere*
@@ -44,6 +50,16 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
     public $calendarTableName = 'calendars';
 
     /**
+     * The table name that will be used for calendars instances.
+     *
+     * A single calendar can have multiple instances, if the calendar is
+     * shared.
+     *
+     * @var string
+     */
+    public $calendarInstancesTableName = 'calendarinstances';
+
+    /**
      * The table name that will be used for calendar objects
      *
      * @var string
@@ -140,16 +156,23 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
     function getCalendarsForUser($principalUri) {
 
         $fields = array_values($this->propertyMap);
-        $fields[] = 'id';
+        $fields[] = 'calendarid';
         $fields[] = 'uri';
         $fields[] = 'synctoken';
         $fields[] = 'components';
         $fields[] = 'principaluri';
         $fields[] = 'transparent';
+        $fields[] = 'access';
 
         // Making fields a comma-delimited list
         $fields = implode(', ', $fields);
-        $stmt = $this->pdo->prepare("SELECT " . $fields . " FROM " . $this->calendarTableName . " WHERE principaluri = ? ORDER BY calendarorder ASC");
+        $stmt = $this->pdo->prepare(<<<SQL
+SELECT {$this->calendarInstancesTableName}.id as id, $fields FROM {$this->calendarInstancesTableName}
+    LEFT JOIN {$this->calendarTableName} ON
+        {$this->calendarInstancesTableName}.calendarid = {$this->calendarTableName}.id
+WHERE principaluri = ? ORDER BY calendarorder ASC
+SQL
+        );
         $stmt->execute([$principalUri]);
 
         $calendars = [];
@@ -161,15 +184,27 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
             }
 
             $calendar = [
-                'id'                                                                 => $row['id'],
+                'id'                                                                 => [(int)$row['calendarid'], (int)$row['id']],
                 'uri'                                                                => $row['uri'],
                 'principaluri'                                                       => $row['principaluri'],
                 '{' . CalDAV\Plugin::NS_CALENDARSERVER . '}getctag'                  => 'http://sabre.io/ns/sync/' . ($row['synctoken'] ? $row['synctoken'] : '0'),
                 '{http://sabredav.org/ns}sync-token'                                 => $row['synctoken'] ? $row['synctoken'] : '0',
                 '{' . CalDAV\Plugin::NS_CALDAV . '}supported-calendar-component-set' => new CalDAV\Xml\Property\SupportedCalendarComponentSet($components),
                 '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-calendar-transp'         => new CalDAV\Xml\Property\ScheduleCalendarTransp($row['transparent'] ? 'transparent' : 'opaque'),
+                'share-resource-uri'                                                 => '/ns/share/' . $row['calendarid'],
             ];
 
+            $calendar['share-access'] = (int)$row['access'];
+            // 1 = owner, 2 = readonly, 3 = readwrite
+            if ($row['access'] > 1) {
+                // We need to find more information about the original owner.
+                //$stmt2 = $this->pdo->prepare('SELECT principaluri FROM ' . $this->calendarInstancesTableName . ' WHERE access = 1 AND id = ?');
+                //$stmt2->execute([$row['id']]);
+
+                // read-only is for backwards compatbility. Might go away in
+                // the future.
+                $calendar['read-only'] = (int)$row['access'] === \Sabre\DAV\Sharing\Plugin::ACCESS_READ;
+            }
 
             foreach ($this->propertyMap as $xmlName => $dbName) {
                 $calendar[$xmlName] = $row[$dbName];
@@ -199,31 +234,38 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
         $fieldNames = [
             'principaluri',
             'uri',
-            'synctoken',
             'transparent',
+            'calendarid',
         ];
         $values = [
             ':principaluri' => $principalUri,
             ':uri'          => $calendarUri,
-            ':synctoken'    => 1,
             ':transparent'  => 0,
         ];
 
-        // Default value
+
         $sccs = '{urn:ietf:params:xml:ns:caldav}supported-calendar-component-set';
-        $fieldNames[] = 'components';
         if (!isset($properties[$sccs])) {
-            $values[':components'] = 'VEVENT,VTODO';
+            // Default value
+            $components = 'VEVENT,VTODO';
         } else {
             if (!($properties[$sccs] instanceof CalDAV\Xml\Property\SupportedCalendarComponentSet)) {
                 throw new DAV\Exception('The ' . $sccs . ' property must be of type: \Sabre\CalDAV\Xml\Property\SupportedCalendarComponentSet');
             }
-            $values[':components'] = implode(',', $properties[$sccs]->getValue());
+            $components = implode(',', $properties[$sccs]->getValue());
         }
         $transp = '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-calendar-transp';
         if (isset($properties[$transp])) {
-            $values[':transparent'] = $properties[$transp]->getValue() === 'transparent';
+            $values[':transparent'] = $properties[$transp]->getValue() === 'transparent' ? 1 : 0;
         }
+        $stmt = $this->pdo->prepare("INSERT INTO " . $this->calendarTableName . " (synctoken, components) VALUES (1, ?)");
+        $stmt->execute([$components]);
+
+        $calendarId = $this->pdo->lastInsertId(
+            $this->calendarTableName . '_id_seq'
+        );
+
+        $values[':calendarid'] = $calendarId;
 
         foreach ($this->propertyMap as $xmlName => $dbName) {
             if (isset($properties[$xmlName])) {
@@ -233,10 +275,14 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
             }
         }
 
-        $stmt = $this->pdo->prepare("INSERT INTO " . $this->calendarTableName . " (" . implode(', ', $fieldNames) . ") VALUES (" . implode(', ', array_keys($values)) . ")");
+        $stmt = $this->pdo->prepare("INSERT INTO " . $this->calendarInstancesTableName . " (" . implode(', ', $fieldNames) . ") VALUES (" . implode(', ', array_keys($values)) . ")");
+
         $stmt->execute($values);
 
-        return $this->pdo->lastInsertId();
+        return [
+            $calendarId,
+            $this->pdo->lastInsertId($this->calendarInstancesTableName . '_id_seq')
+        ];
 
     }
 
@@ -252,16 +298,21 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      *
      * Read the PropPatch documenation for more info and examples.
      *
-     * @param string $calendarId
+     * @param mixed $calendarId
      * @param \Sabre\DAV\PropPatch $propPatch
      * @return void
      */
     function updateCalendar($calendarId, \Sabre\DAV\PropPatch $propPatch) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $supportedProperties = array_keys($this->propertyMap);
         $supportedProperties[] = '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-calendar-transp';
 
-        $propPatch->handle($supportedProperties, function($mutations) use ($calendarId) {
+        $propPatch->handle($supportedProperties, function($mutations) use ($calendarId, $instanceId) {
             $newValues = [];
             foreach ($mutations as $propertyName => $propertyValue) {
 
@@ -282,8 +333,8 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
                 $valuesSql[] = $fieldName . ' = ?';
             }
 
-            $stmt = $this->pdo->prepare("UPDATE " . $this->calendarTableName . " SET " . implode(', ', $valuesSql) . " WHERE id = ?");
-            $newValues['id'] = $calendarId;
+            $stmt = $this->pdo->prepare("UPDATE " . $this->calendarInstancesTableName . " SET " . implode(', ', $valuesSql) . " WHERE id = ?");
+            $newValues['id'] = $instanceId;
             $stmt->execute(array_values($newValues));
 
             $this->addChange($calendarId, "", 2);
@@ -297,19 +348,49 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
     /**
      * Delete a calendar and all it's objects
      *
-     * @param string $calendarId
+     * @param mixed $calendarId
      * @return void
      */
     function deleteCalendar($calendarId) {
 
-        $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarObjectTableName . ' WHERE calendarid = ?');
-        $stmt->execute([$calendarId]);
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
 
-        $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarTableName . ' WHERE id = ?');
-        $stmt->execute([$calendarId]);
+        $stmt = $this->pdo->prepare('SELECT access FROM ' . $this->calendarInstancesTableName . ' where id = ?');
+        $stmt->execute([$instanceId]);
+        $access = (int)$stmt->fetchColumn();
+
+        if ($access === \Sabre\DAV\Sharing\Plugin::ACCESS_SHAREDOWNER) {
+
+            /**
+             * If the user is the owner of the calendar, we delete all data and all
+             * instances.
+             **/
+            $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarObjectTableName . ' WHERE calendarid = ?');
+            $stmt->execute([$calendarId]);
+
+            $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarChangesTableName . ' WHERE calendarid = ?');
+            $stmt->execute([$calendarId]);
+
+            $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarInstancesTableName . ' WHERE calendarid = ?');
+            $stmt->execute([$calendarId]);
+
+            $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarTableName . ' WHERE id = ?');
+            $stmt->execute([$calendarId]);
+
+        } else {
+
+            /**
+             * If it was an instance of a shared calendar, we only delete that
+             * instance.
+             */
+            $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarInstancesTableName . ' WHERE id = ?');
+            $stmt->execute([$instanceId]);
+
+        }
 
-        $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarChangesTableName . ' WHERE calendarid = ?');
-        $stmt->execute([$calendarId]);
 
     }
 
@@ -341,11 +422,16 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      * used/fetched to determine these numbers. If both are specified the
      * amount of times this is needed is reduced by a great degree.
      *
-     * @param string $calendarId
+     * @param mixed $calendarId
      * @return array
      */
     function getCalendarObjects($calendarId) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $stmt = $this->pdo->prepare('SELECT id, uri, lastmodified, etag, calendarid, size, componenttype FROM ' . $this->calendarObjectTableName . ' WHERE calendarid = ?');
         $stmt->execute([$calendarId]);
 
@@ -354,9 +440,8 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
             $result[] = [
                 'id'           => $row['id'],
                 'uri'          => $row['uri'],
-                'lastmodified' => $row['lastmodified'],
+                'lastmodified' => (int)$row['lastmodified'],
                 'etag'         => '"' . $row['etag'] . '"',
-                'calendarid'   => $row['calendarid'],
                 'size'         => (int)$row['size'],
                 'component'    => strtolower($row['componenttype']),
             ];
@@ -378,12 +463,17 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      *
      * This method must return null if the object did not exist.
      *
-     * @param string $calendarId
+     * @param mixed $calendarId
      * @param string $objectUri
      * @return array|null
      */
     function getCalendarObject($calendarId, $objectUri) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $stmt = $this->pdo->prepare('SELECT id, uri, lastmodified, etag, calendarid, size, calendardata, componenttype FROM ' . $this->calendarObjectTableName . ' WHERE calendarid = ? AND uri = ?');
         $stmt->execute([$calendarId, $objectUri]);
         $row = $stmt->fetch(\PDO::FETCH_ASSOC);
@@ -393,9 +483,8 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
         return [
             'id'            => $row['id'],
             'uri'           => $row['uri'],
-            'lastmodified'  => $row['lastmodified'],
+            'lastmodified'  => (int)$row['lastmodified'],
             'etag'          => '"' . $row['etag'] . '"',
-            'calendarid'    => $row['calendarid'],
             'size'          => (int)$row['size'],
             'calendardata'  => $row['calendardata'],
             'component'     => strtolower($row['componenttype']),
@@ -417,6 +506,11 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      */
     function getMultipleCalendarObjects($calendarId, array $uris) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $query = 'SELECT id, uri, lastmodified, etag, calendarid, size, calendardata, componenttype FROM ' . $this->calendarObjectTableName . ' WHERE calendarid = ? AND uri IN (';
         // Inserting a whole bunch of question marks
         $query .= implode(',', array_fill(0, count($uris), '?'));
@@ -431,9 +525,8 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
             $result[] = [
                 'id'           => $row['id'],
                 'uri'          => $row['uri'],
-                'lastmodified' => $row['lastmodified'],
+                'lastmodified' => (int)$row['lastmodified'],
                 'etag'         => '"' . $row['etag'] . '"',
-                'calendarid'   => $row['calendarid'],
                 'size'         => (int)$row['size'],
                 'calendardata' => $row['calendardata'],
                 'component'    => strtolower($row['componenttype']),
@@ -465,6 +558,11 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      */
     function createCalendarObject($calendarId, $objectUri, $calendarData) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $extraData = $this->getDenormalizedData($calendarData);
 
         $stmt = $this->pdo->prepare('INSERT INTO ' . $this->calendarObjectTableName . ' (calendarid, uri, calendardata, lastmodified, etag, size, componenttype, firstoccurence, lastoccurence, uid) VALUES (?,?,?,?,?,?,?,?,?,?)');
@@ -506,6 +604,11 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      */
     function updateCalendarObject($calendarId, $objectUri, $calendarData) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $extraData = $this->getDenormalizedData($calendarData);
 
         $stmt = $this->pdo->prepare('UPDATE ' . $this->calendarObjectTableName . ' SET calendardata = ?, lastmodified = ?, etag = ?, size = ?, componenttype = ?, firstoccurence = ?, lastoccurence = ?, uid = ? WHERE calendarid = ? AND uri = ?');
@@ -583,6 +686,10 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
                 }
 
             }
+            
+            // Ensure Occurence values are positive
+            if ($firstOccurence < 0) $firstOccurence = 0;
+            if ($lastOccurence < 0) $lastOccurence = 0;
         }
 
         // Destroy circular references to PHP will GC the object.
@@ -604,12 +711,17 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      *
      * The object uri is only the basename, or filename and not a full path.
      *
-     * @param string $calendarId
+     * @param mixed $calendarId
      * @param string $objectUri
      * @return void
      */
     function deleteCalendarObject($calendarId, $objectUri) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $stmt = $this->pdo->prepare('DELETE FROM ' . $this->calendarObjectTableName . ' WHERE calendarid = ? AND uri = ?');
         $stmt->execute([$calendarId, $objectUri]);
 
@@ -665,12 +777,17 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
      * This specific implementation (for the PDO) backend optimizes filters on
      * specific components, and VEVENT time-ranges.
      *
-     * @param string $calendarId
+     * @param mixed $calendarId
      * @param array $filters
      * @return array
      */
     function calendarQuery($calendarId, array $filters) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         $componentType = null;
         $requirePostFilter = true;
         $timeRange = null;
@@ -766,14 +883,14 @@ class PDO extends AbstractBackend implements SyncSupport, SubscriptionSupport, S
 
         $query = <<<SQL
 SELECT
-    calendars.uri AS calendaruri, calendarobjects.uri as objecturi
+    calendar_instances.uri AS calendaruri, calendarobjects.uri as objecturi
 FROM
     $this->calendarObjectTableName AS calendarobjects
 LEFT JOIN
-    $this->calendarTableName AS calendars
-    ON calendarobjects.calendarid = calendars.id
+    $this->calendarInstancesTableName AS calendar_instances
+    ON calendarobjects.calendarid = calendar_instances.calendarid
 WHERE
-    calendars.principaluri = ?
+    calendar_instances.principaluri = ?
     AND
     calendarobjects.uid = ?
 SQL;
@@ -837,7 +954,7 @@ SQL;
      *
      * The limit is 'suggestive'. You are free to ignore it.
      *
-     * @param string $calendarId
+     * @param mixed $calendarId
      * @param string $syncToken
      * @param int $syncLevel
      * @param int $limit
@@ -845,6 +962,11 @@ SQL;
      */
     function getChangesForCalendar($calendarId, $syncToken, $syncLevel, $limit = null) {
 
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
         // Current synctoken
         $stmt = $this->pdo->prepare('SELECT synctoken FROM ' . $this->calendarTableName . ' WHERE id = ?');
         $stmt->execute([ $calendarId ]);
@@ -1043,7 +1165,9 @@ SQL;
         $stmt = $this->pdo->prepare("INSERT INTO " . $this->calendarSubscriptionsTableName . " (" . implode(', ', $fieldNames) . ") VALUES (" . implode(', ', array_keys($values)) . ")");
         $stmt->execute($values);
 
-        return $this->pdo->lastInsertId();
+        return $this->pdo->lastInsertId(
+            $this->calendarSubscriptionsTableName . '_id_seq'
+        );
 
     }
 
@@ -1207,4 +1331,179 @@ SQL;
 
     }
 
+    /**
+     * Updates the list of shares.
+     *
+     * @param mixed $calendarId
+     * @param \Sabre\DAV\Xml\Element\Sharee[] $sharees
+     * @return void
+     */
+    function updateInvites($calendarId, array $sharees) {
+
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to $calendarId is expected to be an array with a calendarId and an instanceId');
+        }
+        $currentInvites = $this->getInvites($calendarId);
+        list($calendarId, $instanceId) = $calendarId;
+
+        $removeStmt = $this->pdo->prepare("DELETE FROM " . $this->calendarInstancesTableName . " WHERE calendarid = ? AND share_href = ? AND access IN (2,3)");
+        $updateStmt = $this->pdo->prepare("UPDATE " . $this->calendarInstancesTableName . " SET access = ?, share_displayname = ?, share_invitestatus = ? WHERE calendarid = ? AND share_href = ?");
+
+        $insertStmt = $this->pdo->prepare('
+INSERT INTO ' . $this->calendarInstancesTableName . '
+    (
+        calendarid,
+        principaluri,
+        access,
+        displayname,
+        uri,
+        description,
+        calendarorder,
+        calendarcolor,
+        timezone,
+        transparent,
+        share_href,
+        share_displayname,
+        share_invitestatus
+    )
+    SELECT
+        ?,
+        ?,
+        ?,
+        displayname,
+        ?,
+        description,
+        calendarorder,
+        calendarcolor,
+        timezone,
+        1,
+        ?,
+        ?,
+        ?
+    FROM ' . $this->calendarInstancesTableName . ' WHERE id = ?');
+
+        foreach ($sharees as $sharee) {
+
+            if ($sharee->access === \Sabre\DAV\Sharing\Plugin::ACCESS_NOACCESS) {
+                // if access was set no NOACCESS, it means access for an
+                // existing sharee was removed.
+                $removeStmt->execute([$calendarId, $sharee->href]);
+                continue;
+            }
+
+            if (is_null($sharee->principal)) {
+                // If the server could not determine the principal automatically,
+                // we will mark the invite status as invalid.
+                $sharee->inviteStatus = \Sabre\DAV\Sharing\Plugin::INVITE_INVALID;
+            } else {
+                // Because sabre/dav does not yet have an invitation system,
+                // every invite is automatically accepted for now.
+                $sharee->inviteStatus = \Sabre\DAV\Sharing\Plugin::INVITE_ACCEPTED;
+            }
+
+            foreach ($currentInvites as $oldSharee) {
+
+                if ($oldSharee->href === $sharee->href) {
+                    // This is an update
+                    $sharee->properties = array_merge(
+                        $oldSharee->properties,
+                        $sharee->properties
+                    );
+                    $updateStmt->execute([
+                        $sharee->access,
+                        isset($sharee->properties['{DAV:}displayname']) ? $sharee->properties['{DAV:}displayname'] : null,
+                        $sharee->inviteStatus ?: $oldSharee->inviteStatus,
+                        $calendarId,
+                        $sharee->href
+                    ]);
+                    continue 2;
+                }
+
+            }
+            // If we got here, it means it was a new sharee
+            $insertStmt->execute([
+                $calendarId,
+                $sharee->principal,
+                $sharee->access,
+                \Sabre\DAV\UUIDUtil::getUUID(),
+                $sharee->href,
+                isset($sharee->properties['{DAV:}displayname']) ? $sharee->properties['{DAV:}displayname'] : null,
+                $sharee->inviteStatus ?: \Sabre\DAV\Sharing\Plugin::INVITE_NORESPONSE,
+                $instanceId
+            ]);
+
+        }
+
+    }
+
+    /**
+     * Returns the list of people whom a calendar is shared with.
+     *
+     * Every item in the returned list must be a Sharee object with at
+     * least the following properties set:
+     *   $href
+     *   $shareAccess
+     *   $inviteStatus
+     *
+     * and optionally:
+     *   $properties
+     *
+     * @param mixed $calendarId
+     * @return \Sabre\DAV\Xml\Element\Sharee[]
+     */
+    function getInvites($calendarId) {
+
+        if (!is_array($calendarId)) {
+            throw new \InvalidArgumentException('The value passed to getInvites() is expected to be an array with a calendarId and an instanceId');
+        }
+        list($calendarId, $instanceId) = $calendarId;
+
+        $query = <<<SQL
+SELECT
+    principaluri,
+    access,
+    share_href,
+    share_displayname,
+    share_invitestatus
+FROM {$this->calendarInstancesTableName}
+WHERE
+    calendarid = ?
+SQL;
+
+        $stmt = $this->pdo->prepare($query);
+        $stmt->execute([$calendarId]);
+
+        $result = [];
+        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+
+            $result[] = new Sharee([
+                'href'   => isset($row['share_href']) ? $row['share_href'] : \Sabre\HTTP\encodePath($row['principaluri']),
+                'access' => (int)$row['access'],
+                /// Everyone is always immediately accepted, for now.
+                'inviteStatus' => (int)$row['share_invitestatus'],
+                'properties'   =>
+                    !empty($row['share_displayname'])
+                    ?  [ '{DAV:}displayname' => $row['share_displayname'] ]
+                    : [],
+                'principal' => $row['principaluri'],
+            ]);
+
+        }
+        return $result;
+
+    }
+
+    /**
+     * Publishes a calendar
+     *
+     * @param mixed $calendarId
+     * @param bool $value
+     * @return void
+     */
+    function setPublishStatus($calendarId, $value) {
+
+        throw new \Exception('Not implemented');
+
+    }
+
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Backend/SharingSupport.php b/vendor/sabre/dav/lib/CalDAV/Backend/SharingSupport.php
index 6a11b0ab1..8b6e074e0 100644
--- a/vendor/sabre/dav/lib/CalDAV/Backend/SharingSupport.php
+++ b/vendor/sabre/dav/lib/CalDAV/Backend/SharingSupport.php
@@ -5,231 +5,48 @@ namespace Sabre\CalDAV\Backend;
 /**
  * Adds support for sharing features to a CalDAV server.
  *
- * Note: This feature is experimental, and may change in between different
- * SabreDAV versions.
+ * CalDAV backends that implement this interface, must make the following
+ * modifications to getCalendarsForUser:
  *
- * Early warning: Currently SabreDAV provides no implementation for this. This
- * is, because in it's current state there is no elegant way to do this.
- * The problem lies in the fact that a real CalDAV server with sharing support
- * would first need email support (with invite notifications), and really also
- * a browser-frontend that allows people to accept or reject these shares.
- *
- * In addition, the CalDAV backends are currently kept as independent as
- * possible, and should not be aware of principals, email addresses or
- * accounts.
- *
- * Adding an implementation for Sharing to standard-sabredav would contradict
- * these goals, so for this reason this is currently not implemented, although
- * it may very well in the future; but probably not before SabreDAV 2.0.
- *
- * The interface works however, so if you implement all this, and do it
- * correctly sharing _will_ work. It's not particularly easy, and I _urge you_
- * to make yourself acquainted with the following document first:
- *
- * https://trac.calendarserver.org/browser/CalendarServer/trunk/doc/Extensions/caldav-sharing.txt
- *
- * An overview
- * ===========
- *
- * Implementing this interface will allow a user to share his or her calendars
- * to other users. Effectively, when a calendar is shared the calendar will
- * show up in both the Sharer's and Sharee's calendar-home root.
- * This interface adds a few methods that ensure that this happens, and there
- * are also a number of new requirements in the base-class you must now follow.
- *
- *
- * How it works
- * ============
- *
- * When a user shares a calendar, the updateShares() method will be called with
- * a list of sharees that are now added, and a list of sharees that have been
- * removed.
- * Removal is instant, but when a sharee is added the sharee first gets a
- * chance to accept or reject the invitation for a share.
- *
- * After a share is accepted, the calendar will be returned from
- * getUserCalendars for both the sharer, and the sharee.
- *
- * If the sharee deletes the calendar, only their share gets deleted. When the
- * owner deletes a calendar, it will be removed for everybody.
- *
- *
- * Notifications
- * =============
- *
- * During all these sharing operations, a lot of notifications are sent back
- * and forward.
- *
- * Whenever the list of sharees for a calendar has been changed (they have been
- * added, removed or modified) all sharees should get a notification for this
- * change.
- * This notification is always represented by:
- *
- * Sabre\CalDAV\Notifications\Notification\Invite
- *
- * In the case of an invite, the sharee may reply with an 'accept' or
- * 'decline'. These are always represented by:
- *
- * Sabre\CalDAV\Notifications\Notification\InviteReply
- *
- *
- * Calendar access by sharees
- * ==========================
- *
- * As mentioned earlier, shared calendars must now also be returned for
- * getCalendarsForUser for sharees. A few things change though.
- *
- * The following properties must be specified:
- *
- * 1. {http://calendarserver.org/ns/}shared-url
- *
- * This property MUST contain the url to the original calendar, that is.. the
- * path to the calendar from the owner.
- *
- * 2. {http://sabredav.org/ns}owner-principal
- *
- * This is a url to to the principal who is sharing the calendar.
- *
- * 3. {http://sabredav.org/ns}read-only
- *
- * This should be either 0 or 1, depending on if the user has read-only or
- * read-write access to the calendar.
- *
- * Only when this is done, the calendar will correctly be marked as a calendar
- * that's shared to him, thus allowing clients to display the correct interface
- * and ACL enforcement.
- *
- * If a sharee deletes their calendar, only their instance of the calendar
- * should be deleted, the original should still exists.
- * Pretty much any 'dead' WebDAV properties on these shared calendars should be
- * specific to a user. This means that if the displayname is changed by a
- * sharee, the original is not affected. This is also true for:
- *   * The description
- *   * The color
- *   * The order
- *   * And any other dead properties.
- *
- * Properties like a ctag should not be different for multiple instances of the
- * calendar.
- *
- * Lastly, objects *within* calendars should also have user-specific data. The
- * two things that are user-specific are:
- *   * VALARM objects
- *   * The TRANSP property
- *
- * This _also_ implies that if a VALARM is deleted by a sharee for some event,
- * this has no effect on the original VALARM.
- *
- * Understandably, the this last requirement is one of the hardest.
- * Realisticly, I can see people ignoring this part of the spec, but that could
- * cause a different set of issues.
- *
- *
- * Publishing
- * ==========
- *
- * When a user publishes a url, the server should generate a 'publish url'.
- * This is a read-only url, anybody can use to consume the calendar feed.
- *
- * Calendars are in one of two states:
- *   * published
- *   * unpublished
- *
- * If a calendar is published, the following property should be returned
- * for each calendar in getCalendarsForUser.
- *
- * {http://calendarserver.org/ns/}publish-url
- *
- * This element should contain a {DAV:}href element, which points to the
- * public url that does not require authentication. Unlike every other href,
- * this url must be absolute.
- *
- * Ideally, the following property is always returned
- *
- * {http://calendarserver.org/ns/}pre-publish-url
- *
- * This property should contain the url that the calendar _would_ have, if it
- * were to be published. iCal uses this to display the url, before the user
- * will actually publish it.
- *
- *
- * Selectively disabling publish or share feature
- * ==============================================
- *
- * If Sabre\CalDAV\Property\AllowedSharingModes is returned from
- * getCalendarsForUser, this allows the server to specify whether either sharing,
- * or publishing is supported.
- *
- * This allows a client to determine in advance which features are available,
- * and update the interface appropriately. If this property is not returned by
- * the backend, the SharingPlugin automatically injects it and assumes both
- * features are available.
+ * 1. Return shared calendars for users.
+ * 2. For every calendar, return calendar-resource-uri. This strings is a URI or
+ *    relative URI reference that must be unique for every calendar, but
+ *    identical for every instance of the same shared calenar.
+ * 3. For every calenar, you must return a share-access element. This element
+ *    should contain one of the Sabre\DAV\Sharing\Plugin:ACCESS_* contants and
+ *    indicates the access level the user has.
  *
  * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
  * @author Evert Pot (http://evertpot.com/)
  * @license http://sabre.io/license/ Modified BSD License
  */
-interface SharingSupport extends NotificationSupport {
+interface SharingSupport extends BackendInterface {
 
     /**
      * Updates the list of shares.
      *
-     * The first array is a list of people that are to be added to the
-     * calendar.
-     *
-     * Every element in the add array has the following properties:
-     *   * href - A url. Usually a mailto: address
-     *   * commonName - Usually a first and last name, or false
-     *   * summary - A description of the share, can also be false
-     *   * readOnly - A boolean value
-     *
-     * Every element in the remove array is just the address string.
-     *
-     * Note that if the calendar is currently marked as 'not shared' by and
-     * this method is called, the calendar should be 'upgraded' to a shared
-     * calendar.
-     *
      * @param mixed $calendarId
-     * @param array $add
-     * @param array $remove
+     * @param \Sabre\DAV\Xml\Element\Sharee[] $sharees
      * @return void
      */
-    function updateShares($calendarId, array $add, array $remove);
+    function updateInvites($calendarId, array $sharees);
 
     /**
      * Returns the list of people whom this calendar is shared with.
      *
-     * Every element in this array should have the following properties:
-     *   * href - Often a mailto: address
-     *   * commonName - Optional, for example a first + last name
-     *   * status - See the Sabre\CalDAV\SharingPlugin::STATUS_ constants.
-     *   * readOnly - boolean
-     *   * summary - Optional, a description for the share
+     * Every item in the returned list must be a Sharee object with at
+     * least the following properties set:
+     *   $href
+     *   $shareAccess
+     *   $inviteStatus
      *
-     * This method may be called by either the original instance of the
-     * calendar, as well as the shared instances. In the case of the shared
-     * instances, it is perfectly acceptable to return an empty array in case
-     * there are privacy concerns.
+     * and optionally:
+     *   $properties
      *
      * @param mixed $calendarId
-     * @return array
-     */
-    function getShares($calendarId);
-
-    /**
-     * This method is called when a user replied to a request to share.
-     *
-     * If the user chose to accept the share, this method should return the
-     * newly created calendar url.
-     *
-     * @param string href The sharee who is replying (often a mailto: address)
-     * @param int status One of the SharingPlugin::STATUS_* constants
-     * @param string $calendarUri The url to the calendar thats being shared
-     * @param string $inReplyTo The unique id this message is a response to
-     * @param string $summary A description of the reply
-     * @return null|string
+     * @return \Sabre\DAV\Xml\Element\Sharee[]
      */
-    function shareReply($href, $status, $calendarUri, $inReplyTo, $summary = null);
+    function getInvites($calendarId);
 
     /**
      * Publishes a calendar
diff --git a/vendor/sabre/dav/lib/CalDAV/Backend/SimplePDO.php b/vendor/sabre/dav/lib/CalDAV/Backend/SimplePDO.php
new file mode 100644
index 000000000..f8238ea9a
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Backend/SimplePDO.php
@@ -0,0 +1,296 @@
+<?php
+
+namespace Sabre\CalDAV\Backend;
+
+use Sabre\CalDAV;
+use Sabre\DAV;
+
+/**
+ * Simple PDO CalDAV backend.
+ *
+ * This class is basically the most minmum example to get a caldav backend up
+ * and running. This class uses the following schema (MySQL example):
+ *
+ * CREATE TABLE simple_calendars (
+ *    id INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
+ *    uri VARBINARY(200) NOT NULL,
+ *    principaluri VARBINARY(200) NOT NULL
+ * );
+ *
+ * CREATE TABLE simple_calendarobjects (
+ *    id INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
+ *    calendarid INT UNSIGNED NOT NULL,
+ *    uri VARBINARY(200) NOT NULL,
+ *    calendardata MEDIUMBLOB
+ * )
+ *
+ * To make this class work, you absolutely need to have the PropertyStorage
+ * plugin enabled.
+ *
+ * @copyright Copyright (C) 2007-2015 fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class SimplePDO extends AbstractBackend {
+
+    /**
+     * pdo
+     *
+     * @var \PDO
+     */
+    protected $pdo;
+
+    /**
+     * Creates the backend
+     *
+     * @param \PDO $pdo
+     */
+    function __construct(\PDO $pdo) {
+
+        $this->pdo = $pdo;
+
+    }
+
+    /**
+     * Returns a list of calendars for a principal.
+     *
+     * Every project is an array with the following keys:
+     *  * id, a unique id that will be used by other functions to modify the
+     *    calendar. This can be the same as the uri or a database key.
+     *  * uri. This is just the 'base uri' or 'filename' of the calendar.
+     *  * principaluri. The owner of the calendar. Almost always the same as
+     *    principalUri passed to this method.
+     *
+     * Furthermore it can contain webdav properties in clark notation. A very
+     * common one is '{DAV:}displayname'.
+     *
+     * Many clients also require:
+     * {urn:ietf:params:xml:ns:caldav}supported-calendar-component-set
+     * For this property, you can just return an instance of
+     * Sabre\CalDAV\Xml\Property\SupportedCalendarComponentSet.
+     *
+     * If you return {http://sabredav.org/ns}read-only and set the value to 1,
+     * ACL will automatically be put in read-only mode.
+     *
+     * @param string $principalUri
+     * @return array
+     */
+    function getCalendarsForUser($principalUri) {
+
+        // Making fields a comma-delimited list
+        $stmt = $this->pdo->prepare("SELECT id, uri FROM simple_calendars WHERE principaluri = ? ORDER BY id ASC");
+        $stmt->execute([$principalUri]);
+
+        $calendars = [];
+        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+
+            $calendars[] = [
+                'id'           => $row['id'],
+                'uri'          => $row['uri'],
+                'principaluri' => $principalUri,
+            ];
+
+        }
+
+        return $calendars;
+
+    }
+
+    /**
+     * Creates a new calendar for a principal.
+     *
+     * If the creation was a success, an id must be returned that can be used
+     * to reference this calendar in other methods, such as updateCalendar.
+     *
+     * @param string $principalUri
+     * @param string $calendarUri
+     * @param array $properties
+     * @return string
+     */
+    function createCalendar($principalUri, $calendarUri, array $properties) {
+
+        $stmt = $this->pdo->prepare("INSERT INTO simple_calendars (principaluri, uri) VALUES (?, ?)");
+        $stmt->execute([$principalUri, $calendarUri]);
+
+        return $this->pdo->lastInsertId();
+
+    }
+
+    /**
+     * Delete a calendar and all it's objects
+     *
+     * @param string $calendarId
+     * @return void
+     */
+    function deleteCalendar($calendarId) {
+
+        $stmt = $this->pdo->prepare('DELETE FROM simple_calendarobjects WHERE calendarid = ?');
+        $stmt->execute([$calendarId]);
+
+        $stmt = $this->pdo->prepare('DELETE FROM simple_calendars WHERE id = ?');
+        $stmt->execute([$calendarId]);
+
+    }
+
+    /**
+     * Returns all calendar objects within a calendar.
+     *
+     * Every item contains an array with the following keys:
+     *   * calendardata - The iCalendar-compatible calendar data
+     *   * uri - a unique key which will be used to construct the uri. This can
+     *     be any arbitrary string, but making sure it ends with '.ics' is a
+     *     good idea. This is only the basename, or filename, not the full
+     *     path.
+     *   * lastmodified - a timestamp of the last modification time
+     *   * etag - An arbitrary string, surrounded by double-quotes. (e.g.:
+     *   '  "abcdef"')
+     *   * size - The size of the calendar objects, in bytes.
+     *   * component - optional, a string containing the type of object, such
+     *     as 'vevent' or 'vtodo'. If specified, this will be used to populate
+     *     the Content-Type header.
+     *
+     * Note that the etag is optional, but it's highly encouraged to return for
+     * speed reasons.
+     *
+     * The calendardata is also optional. If it's not returned
+     * 'getCalendarObject' will be called later, which *is* expected to return
+     * calendardata.
+     *
+     * If neither etag or size are specified, the calendardata will be
+     * used/fetched to determine these numbers. If both are specified the
+     * amount of times this is needed is reduced by a great degree.
+     *
+     * @param string $calendarId
+     * @return array
+     */
+    function getCalendarObjects($calendarId) {
+
+        $stmt = $this->pdo->prepare('SELECT id, uri, calendardata FROM simple_calendarobjects WHERE calendarid = ?');
+        $stmt->execute([$calendarId]);
+
+        $result = [];
+        foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) as $row) {
+            $result[] = [
+                'id'           => $row['id'],
+                'uri'          => $row['uri'],
+                'etag'         => '"' . md5($row['calendardata']) . '"',
+                'calendarid'   => $calendarId,
+                'size'         => strlen($row['calendardata']),
+                'calendardata' => $row['calendardata'],
+            ];
+        }
+
+        return $result;
+
+    }
+
+    /**
+     * Returns information from a single calendar object, based on it's object
+     * uri.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * The returned array must have the same keys as getCalendarObjects. The
+     * 'calendardata' object is required here though, while it's not required
+     * for getCalendarObjects.
+     *
+     * This method must return null if the object did not exist.
+     *
+     * @param string $calendarId
+     * @param string $objectUri
+     * @return array|null
+     */
+    function getCalendarObject($calendarId, $objectUri) {
+
+        $stmt = $this->pdo->prepare('SELECT id, uri, calendardata FROM simple_calendarobjects WHERE calendarid = ? AND uri = ?');
+        $stmt->execute([$calendarId, $objectUri]);
+        $row = $stmt->fetch(\PDO::FETCH_ASSOC);
+
+        if (!$row) return null;
+
+        return [
+            'id'            => $row['id'],
+            'uri'           => $row['uri'],
+            'etag'          => '"' . md5($row['calendardata']) . '"',
+            'calendarid'    => $calendarId,
+            'size'          => strlen($row['calendardata']),
+            'calendardata'  => $row['calendardata'],
+         ];
+
+    }
+
+    /**
+     * Creates a new calendar object.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * It is possible return an etag from this function, which will be used in
+     * the response to this PUT request. Note that the ETag must be surrounded
+     * by double-quotes.
+     *
+     * However, you should only really return this ETag if you don't mangle the
+     * calendar-data. If the result of a subsequent GET to this object is not
+     * the exact same as this request body, you should omit the ETag.
+     *
+     * @param mixed $calendarId
+     * @param string $objectUri
+     * @param string $calendarData
+     * @return string|null
+     */
+    function createCalendarObject($calendarId, $objectUri, $calendarData) {
+
+        $stmt = $this->pdo->prepare('INSERT INTO simple_calendarobjects (calendarid, uri, calendardata) VALUES (?,?,?)');
+        $stmt->execute([
+            $calendarId,
+            $objectUri,
+            $calendarData
+        ]);
+
+        return '"' . md5($calendarData) . '"';
+
+    }
+
+    /**
+     * Updates an existing calendarobject, based on it's uri.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * It is possible return an etag from this function, which will be used in
+     * the response to this PUT request. Note that the ETag must be surrounded
+     * by double-quotes.
+     *
+     * However, you should only really return this ETag if you don't mangle the
+     * calendar-data. If the result of a subsequent GET to this object is not
+     * the exact same as this request body, you should omit the ETag.
+     *
+     * @param mixed $calendarId
+     * @param string $objectUri
+     * @param string $calendarData
+     * @return string|null
+     */
+    function updateCalendarObject($calendarId, $objectUri, $calendarData) {
+
+        $stmt = $this->pdo->prepare('UPDATE simple_calendarobjects SET calendardata = ? WHERE calendarid = ? AND uri = ?');
+        $stmt->execute([$calendarData, $calendarId, $objectUri]);
+
+        return '"' . md5($calendarData) . '"';
+
+    }
+
+    /**
+     * Deletes an existing calendar object.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * @param string $calendarId
+     * @param string $objectUri
+     * @return void
+     */
+    function deleteCalendarObject($calendarId, $objectUri) {
+
+        $stmt = $this->pdo->prepare('DELETE FROM simple_calendarobjects WHERE calendarid = ? AND uri = ?');
+        $stmt->execute([$calendarId, $objectUri]);
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Calendar.php b/vendor/sabre/dav/lib/CalDAV/Calendar.php
index ff8e19b15..90ace0d21 100644
--- a/vendor/sabre/dav/lib/CalDAV/Calendar.php
+++ b/vendor/sabre/dav/lib/CalDAV/Calendar.php
@@ -18,6 +18,8 @@ use Sabre\DAV\PropPatch;
  */
 class Calendar implements ICalendar, DAV\IProperties, DAV\Sync\ISyncCollection, DAV\IMultiGet {
 
+    use DAVACL\ACLTrait;
+
     /**
      * This is an array with calendar information
      *
@@ -86,7 +88,7 @@ class Calendar implements ICalendar, DAV\IProperties, DAV\Sync\ISyncCollection,
 
         foreach ($this->calendarInfo as $propName => $propValue) {
 
-            if ($propName[0] === '{')
+            if (!is_null($propValue) && $propName[0] === '{')
                 $response[$propName] = $this->calendarInfo[$propName];
 
         }
@@ -227,7 +229,7 @@ class Calendar implements ICalendar, DAV\IProperties, DAV\Sync\ISyncCollection,
     /**
      * Returns the last modification date as a unix timestamp.
      *
-     * @return void
+     * @return null
      */
     function getLastModified() {
 
@@ -249,19 +251,6 @@ class Calendar implements ICalendar, DAV\IProperties, DAV\Sync\ISyncCollection,
     }
 
     /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -360,50 +349,6 @@ class Calendar implements ICalendar, DAV\IProperties, DAV\Sync\ISyncCollection,
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('Changing ACL is not yet supported');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See \Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        $default = DAVACL\Plugin::getDefaultSupportedPrivilegeSet();
-
-        // We need to inject 'read-free-busy' in the tree, aggregated under
-        // {DAV:}read.
-        foreach ($default['aggregates'] as &$agg) {
-
-            if ($agg['privilege'] !== '{DAV:}read') continue;
-
-            $agg['aggregates'][] = [
-                'privilege' => '{' . Plugin::NS_CALDAV . '}read-free-busy',
-            ];
-
-        }
-        return $default;
-
-    }
 
     /**
      * Performs a calendar-query on the contents of this calendar.
diff --git a/vendor/sabre/dav/lib/CalDAV/CalendarHome.php b/vendor/sabre/dav/lib/CalDAV/CalendarHome.php
index a53f829e2..0a4bfb68f 100644
--- a/vendor/sabre/dav/lib/CalDAV/CalendarHome.php
+++ b/vendor/sabre/dav/lib/CalDAV/CalendarHome.php
@@ -22,6 +22,8 @@ use Sabre\HTTP\URLUtil;
  */
 class CalendarHome implements DAV\IExtendedCollection, DAVACL\IACL {
 
+    use DAVACL\ACLTrait;
+
     /**
      * CalDAV backend
      *
@@ -147,11 +149,7 @@ class CalendarHome implements DAV\IExtendedCollection, DAVACL\IACL {
         foreach ($this->caldavBackend->getCalendarsForUser($this->principalInfo['uri']) as $calendar) {
             if ($calendar['uri'] === $name) {
                 if ($this->caldavBackend instanceof Backend\SharingSupport) {
-                    if (isset($calendar['{http://calendarserver.org/ns/}shared-url'])) {
-                        return new SharedCalendar($this->caldavBackend, $calendar);
-                    } else {
-                        return new ShareableCalendar($this->caldavBackend, $calendar);
-                    }
+                    return new SharedCalendar($this->caldavBackend, $calendar);
                 } else {
                     return new Calendar($this->caldavBackend, $calendar);
                 }
@@ -198,11 +196,7 @@ class CalendarHome implements DAV\IExtendedCollection, DAVACL\IACL {
         $objs = [];
         foreach ($calendars as $calendar) {
             if ($this->caldavBackend instanceof Backend\SharingSupport) {
-                if (isset($calendar['{http://calendarserver.org/ns/}shared-url'])) {
-                    $objs[] = new SharedCalendar($this->caldavBackend, $calendar);
-                } else {
-                    $objs[] = new ShareableCalendar($this->caldavBackend, $calendar);
-                }
+                $objs[] = new SharedCalendar($this->caldavBackend, $calendar);
             } else {
                 $objs[] = new Calendar($this->caldavBackend, $calendar);
             }
@@ -278,11 +272,9 @@ class CalendarHome implements DAV\IExtendedCollection, DAVACL\IACL {
     }
 
     /**
-     * Returns the owner principal
+     * Returns the owner of the calendar home.
      *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
+     * @return string
      */
     function getOwner() {
 
@@ -291,19 +283,6 @@ class CalendarHome implements DAV\IExtendedCollection, DAVACL\IACL {
     }
 
     /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -348,37 +327,6 @@ class CalendarHome implements DAV\IExtendedCollection, DAVACL\IACL {
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('Changing ACL is not yet supported');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
 
     /**
      * This method is called when a user replied to a request to share.
diff --git a/vendor/sabre/dav/lib/CalDAV/CalendarObject.php b/vendor/sabre/dav/lib/CalDAV/CalendarObject.php
index 393ca4cbd..001b35112 100644
--- a/vendor/sabre/dav/lib/CalDAV/CalendarObject.php
+++ b/vendor/sabre/dav/lib/CalDAV/CalendarObject.php
@@ -11,6 +11,8 @@ namespace Sabre\CalDAV;
  */
 class CalendarObject extends \Sabre\DAV\File implements ICalendarObject, \Sabre\DAVACL\IACL {
 
+    use \Sabre\DAVACL\ACLTrait;
+
     /**
      * Sabre\CalDAV\Backend\BackendInterface
      *
@@ -192,19 +194,6 @@ class CalendarObject extends \Sabre\DAV\File implements ICalendarObject, \Sabre\
     }
 
     /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -226,22 +215,12 @@ class CalendarObject extends \Sabre\DAV\File implements ICalendarObject, \Sabre\
         // The default ACL
         return [
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->calendarInfo['principaluri'],
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
+                'privilege' => '{DAV:}all',
                 'principal' => $this->calendarInfo['principaluri'],
                 'protected' => true,
             ],
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
+                'privilege' => '{DAV:}all',
                 'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
                 'protected' => true,
             ],
@@ -255,36 +234,4 @@ class CalendarObject extends \Sabre\DAV\File implements ICalendarObject, \Sabre\
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new \Sabre\DAV\Exception\MethodNotAllowed('Changing ACL is not yet supported');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See \Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/ICSExportPlugin.php b/vendor/sabre/dav/lib/CalDAV/ICSExportPlugin.php
index 8c296d50f..a3a824c71 100644
--- a/vendor/sabre/dav/lib/CalDAV/ICSExportPlugin.php
+++ b/vendor/sabre/dav/lib/CalDAV/ICSExportPlugin.php
@@ -170,13 +170,13 @@ class ICSExportPlugin extends DAV\ServerPlugin {
     protected function generateResponse($path, $start, $end, $expand, $componentType, $format, $properties, ResponseInterface $response) {
 
         $calDataProp = '{' . Plugin::NS_CALDAV . '}calendar-data';
+        $calendarNode = $this->server->tree->getNodeForPath($path);
 
         $blobs = [];
         if ($start || $end || $componentType) {
 
             // If there was a start or end filter, we need to enlist
             // calendarQuery for speed.
-            $calendarNode = $this->server->tree->getNodeForPath($path);
             $queryResult = $calendarNode->calendarQuery([
                 'name'         => 'VCALENDAR',
                 'comp-filters' => [
@@ -246,17 +246,29 @@ class ICSExportPlugin extends DAV\ServerPlugin {
             $mergedCalendar = $mergedCalendar->expand($start, $end, $calendarTimeZone);
         }
 
-        $response->setHeader('Content-Type', $format);
+        $filenameExtension = '.ics';
 
         switch ($format) {
             case 'text/calendar' :
                 $mergedCalendar = $mergedCalendar->serialize();
+                $filenameExtension = '.ics';
                 break;
             case 'application/calendar+json' :
                 $mergedCalendar = json_encode($mergedCalendar->jsonSerialize());
+                $filenameExtension = '.json';
                 break;
         }
 
+        $filename = preg_replace(
+            '/[^a-zA-Z0-9-_ ]/um',
+            '',
+            $calendarNode->getName()
+        );
+        $filename .= '-' . date('Y-m-d') . $filenameExtension;
+
+        $response->setHeader('Content-Disposition', 'attachment; filename="' . $filename . '"');
+        $response->setHeader('Content-Type', $format);
+
         $response->setStatus(200);
         $response->setBody($mergedCalendar);
 
@@ -272,11 +284,11 @@ class ICSExportPlugin extends DAV\ServerPlugin {
     function mergeObjects(array $properties, array $inputObjects) {
 
         $calendar = new VObject\Component\VCalendar();
-        $calendar->version = '2.0';
+        $calendar->VERSION = '2.0';
         if (DAV\Server::$exposeVersion) {
-            $calendar->prodid = '-//SabreDAV//SabreDAV ' . DAV\Version::VERSION . '//EN';
+            $calendar->PRODID = '-//SabreDAV//SabreDAV ' . DAV\Version::VERSION . '//EN';
         } else {
-            $calendar->prodid = '-//SabreDAV//SabreDAV//EN';
+            $calendar->PRODID = '-//SabreDAV//SabreDAV//EN';
         }
         if (isset($properties['{DAV:}displayname'])) {
             $calendar->{'X-WR-CALNAME'} = $properties['{DAV:}displayname'];
diff --git a/vendor/sabre/dav/lib/CalDAV/IShareableCalendar.php b/vendor/sabre/dav/lib/CalDAV/IShareableCalendar.php
index cfda91a55..7420d94f7 100644
--- a/vendor/sabre/dav/lib/CalDAV/IShareableCalendar.php
+++ b/vendor/sabre/dav/lib/CalDAV/IShareableCalendar.php
@@ -5,7 +5,7 @@ namespace Sabre\CalDAV;
 /**
  * This interface represents a Calendar that can be shared with other users.
  *
- * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @copyright Copyright (C) 2007-2015 fruux GmbH (https://fruux.com/).
  * @author Evert Pot (http://evertpot.com/)
  * @license http://sabre.io/license/ Modified BSD License
  */
diff --git a/vendor/sabre/dav/lib/CalDAV/ISharedCalendar.php b/vendor/sabre/dav/lib/CalDAV/ISharedCalendar.php
index 84442ac21..15f3b5335 100644
--- a/vendor/sabre/dav/lib/CalDAV/ISharedCalendar.php
+++ b/vendor/sabre/dav/lib/CalDAV/ISharedCalendar.php
@@ -2,6 +2,8 @@
 
 namespace Sabre\CalDAV;
 
+use Sabre\DAV\Sharing\ISharedNode;
+
 /**
  * This interface represents a Calendar that is shared by a different user.
  *
@@ -9,28 +11,16 @@ namespace Sabre\CalDAV;
  * @author Evert Pot (http://evertpot.com/)
  * @license http://sabre.io/license/ Modified BSD License
  */
-interface ISharedCalendar extends ICalendar {
-
-    /**
-     * This method should return the url of the owners' copy of the shared
-     * calendar.
-     *
-     * @return string
-     */
-    function getSharedUrl();
+interface ISharedCalendar extends ISharedNode {
 
     /**
-     * Returns the list of people whom this calendar is shared with.
+     * Marks this calendar as published.
      *
-     * Every element in this array should have the following properties:
-     *   * href - Often a mailto: address
-     *   * commonName - Optional, for example a first + last name
-     *   * status - See the Sabre\CalDAV\SharingPlugin::STATUS_ constants.
-     *   * readOnly - boolean
-     *   * summary - Optional, a description for the share
+     * Publishing a calendar should automatically create a read-only, public,
+     * subscribable calendar.
      *
-     * @return array
+     * @param bool $value
+     * @return void
      */
-    function getShares();
-
+    function setPublishStatus($value);
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Notifications/Collection.php b/vendor/sabre/dav/lib/CalDAV/Notifications/Collection.php
index 1fcc1171c..5fda61dfa 100644
--- a/vendor/sabre/dav/lib/CalDAV/Notifications/Collection.php
+++ b/vendor/sabre/dav/lib/CalDAV/Notifications/Collection.php
@@ -22,6 +22,8 @@ use Sabre\DAVACL;
  */
 class Collection extends DAV\Collection implements ICollection, DAVACL\IACL {
 
+    use DAVACL\ACLTrait;
+
     /**
      * The notification backend
      *
@@ -96,78 +98,4 @@ class Collection extends DAV\Collection implements ICollection, DAVACL\IACL {
 
     }
 
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
-     * Returns a list of ACE's for this node.
-     *
-     * Each ACE has the following properties:
-     *   * 'privilege', a string such as {DAV:}read or {DAV:}write. These are
-     *     currently the only supported privileges
-     *   * 'principal', a url to the principal who owns the node
-     *   * 'protected' (optional), indicating that this ACE is not allowed to
-     *      be updated.
-     *
-     * @return array
-     */
-    function getACL() {
-
-        return [
-            [
-                'principal' => $this->getOwner(),
-                'privilege' => '{DAV:}read',
-                'protected' => true,
-            ],
-            [
-                'principal' => $this->getOwner(),
-                'privilege' => '{DAV:}write',
-                'protected' => true,
-            ]
-        ];
-
-    }
-
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's as an array argument.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\NotImplemented('Updating ACLs is not implemented here');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Notifications/Node.php b/vendor/sabre/dav/lib/CalDAV/Notifications/Node.php
index 47e78d5de..11df0c94b 100644
--- a/vendor/sabre/dav/lib/CalDAV/Notifications/Node.php
+++ b/vendor/sabre/dav/lib/CalDAV/Notifications/Node.php
@@ -20,6 +20,8 @@ use Sabre\DAVACL;
  */
 class Node extends DAV\File implements INode, DAVACL\IACL {
 
+    use DAVACL\ACLTrait;
+
     /**
      * The notification backend
      *
@@ -116,78 +118,4 @@ class Node extends DAV\File implements INode, DAVACL\IACL {
 
     }
 
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
-     * Returns a list of ACE's for this node.
-     *
-     * Each ACE has the following properties:
-     *   * 'privilege', a string such as {DAV:}read or {DAV:}write. These are
-     *     currently the only supported privileges
-     *   * 'principal', a url to the principal who owns the node
-     *   * 'protected' (optional), indicating that this ACE is not allowed to
-     *      be updated.
-     *
-     * @return array
-     */
-    function getACL() {
-
-        return [
-            [
-                'principal' => $this->getOwner(),
-                'privilege' => '{DAV:}read',
-                'protected' => true,
-            ],
-            [
-                'principal' => $this->getOwner(),
-                'privilege' => '{DAV:}write',
-                'protected' => true,
-            ]
-        ];
-
-    }
-
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's as an array argument.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\NotImplemented('Updating ACLs is not implemented here');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Plugin.php b/vendor/sabre/dav/lib/CalDAV/Plugin.php
index 663490023..71ba75206 100644
--- a/vendor/sabre/dav/lib/CalDAV/Plugin.php
+++ b/vendor/sabre/dav/lib/CalDAV/Plugin.php
@@ -5,8 +5,9 @@ namespace Sabre\CalDAV;
 use DateTimeZone;
 use Sabre\DAV;
 use Sabre\DAV\Exception\BadRequest;
+use Sabre\DAV\INode;
 use Sabre\DAV\MkCol;
-use Sabre\DAV\Xml\Property\Href;
+use Sabre\DAV\Xml\Property\LocalHref;
 use Sabre\DAVACL;
 use Sabre\VObject;
 use Sabre\HTTP;
@@ -186,6 +187,7 @@ class Plugin extends DAV\ServerPlugin {
         $server->on('beforeCreateFile',    [$this, 'beforeCreateFile']);
         $server->on('beforeWriteContent',  [$this, 'beforeWriteContent']);
         $server->on('afterMethod:GET',     [$this, 'httpAfterGET']);
+        $server->on('getSupportedPrivilegeSet', [$this, 'getSupportedPrivilegeSet']);
 
         $server->xml->namespaceMap[self::NS_CALDAV] = 'cal';
         $server->xml->namespaceMap[self::NS_CALENDARSERVER] = 'cs';
@@ -233,9 +235,10 @@ class Plugin extends DAV\ServerPlugin {
      *
      * @param string $reportName
      * @param mixed $report
+     * @param mixed $path
      * @return bool
      */
-    function report($reportName, $report) {
+    function report($reportName, $report, $path) {
 
         switch ($reportName) {
             case '{' . self::NS_CALDAV . '}calendar-multiget' :
@@ -341,7 +344,7 @@ class Plugin extends DAV\ServerPlugin {
 
                 $calendarHomePath = $this->getCalendarHomeForPrincipal($principalUrl);
                 if (is_null($calendarHomePath)) return null;
-                return new Href($calendarHomePath . '/');
+                return new LocalHref($calendarHomePath . '/');
 
             });
             // The calendar-user-address-set property is basically mapped to
@@ -349,7 +352,7 @@ class Plugin extends DAV\ServerPlugin {
             $propFind->handle('{' . self::NS_CALDAV . '}calendar-user-address-set', function() use ($node) {
                 $addresses = $node->getAlternateUriSet();
                 $addresses[] = $this->server->getBaseUri() . $node->getPrincipalUrl() . '/';
-                return new Href($addresses, false);
+                return new LocalHref($addresses);
             });
             // For some reason somebody thought it was a good idea to add
             // another one of these properties. We're supporting it too.
@@ -394,8 +397,8 @@ class Plugin extends DAV\ServerPlugin {
 
                 }
 
-                $propFind->set($propRead, new Href($readList));
-                $propFind->set($propWrite, new Href($writeList));
+                $propFind->set($propRead, new LocalHref($readList));
+                $propFind->set($propWrite, new LocalHref($writeList));
 
             }
 
@@ -821,11 +824,7 @@ class Plugin extends DAV\ServerPlugin {
             $data = stream_get_contents($data);
         }
 
-        $before = md5($data);
-        // Converting the data to unicode, if needed.
-        $data = DAV\StringUtil::ensureUTF8($data);
-
-        if ($before !== md5($data)) $modified = true;
+        $before = $data;
 
         try {
 
@@ -865,7 +864,7 @@ class Plugin extends DAV\ServerPlugin {
         }
 
         $foundType = null;
-        $foundUID = null;
+
         foreach ($vobj->getComponents() as $component) {
             switch ($component->name) {
                 case 'VTIMEZONE' :
@@ -873,31 +872,59 @@ class Plugin extends DAV\ServerPlugin {
                 case 'VEVENT' :
                 case 'VTODO' :
                 case 'VJOURNAL' :
-                    if (is_null($foundType)) {
-                        $foundType = $component->name;
-                        if (!in_array($foundType, $supportedComponents)) {
-                            throw new Exception\InvalidComponentType('This calendar only supports ' . implode(', ', $supportedComponents) . '. We found a ' . $foundType);
-                        }
-                        if (!isset($component->UID)) {
-                            throw new DAV\Exception\BadRequest('Every ' . $component->name . ' component must have an UID');
-                        }
-                        $foundUID = (string)$component->UID;
-                    } else {
-                        if ($foundType !== $component->name) {
-                            throw new DAV\Exception\BadRequest('A calendar object must only contain 1 component. We found a ' . $component->name . ' as well as a ' . $foundType);
-                        }
-                        if ($foundUID !== (string)$component->UID) {
-                            throw new DAV\Exception\BadRequest('Every ' . $component->name . ' in this object must have identical UIDs');
-                        }
-                    }
+                    $foundType = $component->name;
                     break;
-                default :
-                    throw new DAV\Exception\BadRequest('You are not allowed to create components of type: ' . $component->name . ' here');
+            }
+
+        }
+
+        if (!$foundType || !in_array($foundType, $supportedComponents)) {
+            throw new Exception\InvalidComponentType('iCalendar objects must at least have a component of type ' . implode(', ', $supportedComponents));
+        }
+
+        $options = VObject\Node::PROFILE_CALDAV;
+        $prefer = $this->server->getHTTPPrefer();
+
+        if ($prefer['handling'] !== 'strict') {
+            $options |= VObject\Node::REPAIR;
+        }
+
+        $messages = $vobj->validate($options);
 
+        $highestLevel = 0;
+        $warningMessage = null;
+
+        // $messages contains a list of problems with the vcard, along with
+        // their severity.
+        foreach ($messages as $message) {
+
+            if ($message['level'] > $highestLevel) {
+                // Recording the highest reported error level.
+                $highestLevel = $message['level'];
+                $warningMessage = $message['message'];
             }
+            switch ($message['level']) {
+
+                case 1 :
+                    // Level 1 means that there was a problem, but it was repaired.
+                    $modified = true;
+                    break;
+                case 2 :
+                    // Level 2 means a warning, but not critical
+                    break;
+                case 3 :
+                    // Level 3 means a critical error
+                    throw new DAV\Exception\UnsupportedMediaType('Validation error in iCalendar: ' . $message['message']);
+
+            }
+
+        }
+        if ($warningMessage) {
+            $response->setHeader(
+                'X-Sabre-Ew-Gross',
+                'iCalendar validation warning: ' . $warningMessage
+            );
         }
-        if (!$foundType)
-            throw new DAV\Exception\BadRequest('iCalendar object must contain at least 1 of VEVENT, VTODO or VJOURNAL');
 
         // We use an extra variable to allow event handles to tell us wether
         // the object was modified or not.
@@ -917,12 +944,12 @@ class Plugin extends DAV\ServerPlugin {
             ]
         );
 
-        if ($subModified) {
+        if ($modified || $subModified) {
             // An event handler told us that it modified the object.
             $data = $vobj->serialize();
 
             // Using md5 to figure out if there was an *actual* change.
-            if (!$modified && $before !== md5($data)) {
+            if (!$modified && strcmp($data, $before) !== 0) {
                 $modified = true;
             }
 
@@ -933,6 +960,22 @@ class Plugin extends DAV\ServerPlugin {
 
     }
 
+    /**
+     * This method is triggered whenever a subsystem reqeuests the privileges
+     * that are supported on a particular node.
+     *
+     * @param INode $node
+     * @param array $supportedPrivilegeSet
+     */
+    function getSupportedPrivilegeSet(INode $node, array &$supportedPrivilegeSet) {
+
+        if ($node instanceof ICalendar) {
+            $supportedPrivilegeSet['{DAV:}read']['aggregates']['{' . self::NS_CALDAV . '}read-free-busy'] = [
+                'abstract'   => false,
+                'aggregates' => [],
+            ];
+        }
+    }
 
     /**
      * This method is used to generate HTML output for the
diff --git a/vendor/sabre/dav/lib/CalDAV/Schedule/Inbox.php b/vendor/sabre/dav/lib/CalDAV/Schedule/Inbox.php
index 13212565e..6b374ea3f 100644
--- a/vendor/sabre/dav/lib/CalDAV/Schedule/Inbox.php
+++ b/vendor/sabre/dav/lib/CalDAV/Schedule/Inbox.php
@@ -17,6 +17,8 @@ use Sabre\VObject;
  */
 class Inbox extends DAV\Collection implements IInbox {
 
+    use DAVACL\ACLTrait;
+
     /**
      * CalDAV backend
      *
@@ -119,19 +121,6 @@ class Inbox extends DAV\Collection implements IInbox {
     }
 
     /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -167,58 +156,11 @@ class Inbox extends DAV\Collection implements IInbox {
                 'protected' => true,
             ],
             [
-                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-deliver-invite',
+                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-deliver',
                 'principal' => '{DAV:}authenticated',
                 'protected' => true,
             ],
-            [
-                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-deliver-reply',
-                'principal' => '{DAV:}authenticated',
-                'protected' => true,
-            ],
-        ];
-
-    }
-
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('You\'re not allowed to update the ACL');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        $ns = '{' . CalDAV\Plugin::NS_CALDAV . '}';
-
-        $default = DAVACL\Plugin::getDefaultSupportedPrivilegeSet();
-        $default['aggregates'][] = [
-            'privilege'  => $ns . 'schedule-deliver',
-            'aggregates' => [
-               ['privilege' => $ns . 'schedule-deliver-invite'],
-               ['privilege' => $ns . 'schedule-deliver-reply'],
-            ],
         ];
-        return $default;
 
     }
 
diff --git a/vendor/sabre/dav/lib/CalDAV/Schedule/Outbox.php b/vendor/sabre/dav/lib/CalDAV/Schedule/Outbox.php
index dabaee2ca..29eefa744 100644
--- a/vendor/sabre/dav/lib/CalDAV/Schedule/Outbox.php
+++ b/vendor/sabre/dav/lib/CalDAV/Schedule/Outbox.php
@@ -19,6 +19,8 @@ use Sabre\DAVACL;
  */
 class Outbox extends DAV\Collection implements IOutbox {
 
+    use DAVACL\ACLTrait;
+
     /**
      * The principal Uri
      *
@@ -75,19 +77,6 @@ class Outbox extends DAV\Collection implements IOutbox {
     }
 
     /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -103,12 +92,7 @@ class Outbox extends DAV\Collection implements IOutbox {
 
         return [
             [
-                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-query-freebusy',
-                'principal' => $this->getOwner(),
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-post-vevent',
+                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-send',
                 'principal' => $this->getOwner(),
                 'protected' => true,
             ],
@@ -118,12 +102,7 @@ class Outbox extends DAV\Collection implements IOutbox {
                 'protected' => true,
             ],
             [
-                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-query-freebusy',
-                'principal' => $this->getOwner() . '/calendar-proxy-write',
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-post-vevent',
+                'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-send',
                 'principal' => $this->getOwner() . '/calendar-proxy-write',
                 'protected' => true,
             ],
@@ -141,44 +120,4 @@ class Outbox extends DAV\Collection implements IOutbox {
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('You\'re not allowed to update the ACL');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        $default = DAVACL\Plugin::getDefaultSupportedPrivilegeSet();
-        $default['aggregates'][] = [
-            'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-query-freebusy',
-        ];
-        $default['aggregates'][] = [
-            'privilege' => '{' . CalDAV\Plugin::NS_CALDAV . '}schedule-post-vevent',
-        ];
-
-        return $default;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Schedule/Plugin.php b/vendor/sabre/dav/lib/CalDAV/Schedule/Plugin.php
index 827d6209b..47511140f 100644
--- a/vendor/sabre/dav/lib/CalDAV/Schedule/Plugin.php
+++ b/vendor/sabre/dav/lib/CalDAV/Schedule/Plugin.php
@@ -5,10 +5,12 @@ namespace Sabre\CalDAV\Schedule;
 use DateTimeZone;
 use Sabre\DAV\Server;
 use Sabre\DAV\ServerPlugin;
+use Sabre\DAV\Sharing;
 use Sabre\DAV\PropFind;
 use Sabre\DAV\PropPatch;
 use Sabre\DAV\INode;
 use Sabre\DAV\Xml\Property\Href;
+use Sabre\DAV\Xml\Property\LocalHref;
 use Sabre\HTTP\RequestInterface;
 use Sabre\HTTP\ResponseInterface;
 use Sabre\VObject;
@@ -100,12 +102,13 @@ class Plugin extends ServerPlugin {
     function initialize(Server $server) {
 
         $this->server = $server;
-        $server->on('method:POST',          [$this, 'httpPost']);
-        $server->on('propFind',             [$this, 'propFind']);
-        $server->on('propPatch',            [$this, 'propPatch']);
-        $server->on('calendarObjectChange', [$this, 'calendarObjectChange']);
-        $server->on('beforeUnbind',         [$this, 'beforeUnbind']);
-        $server->on('schedule',             [$this, 'scheduleLocalDelivery']);
+        $server->on('method:POST',              [$this, 'httpPost']);
+        $server->on('propFind',                 [$this, 'propFind']);
+        $server->on('propPatch',                [$this, 'propPatch']);
+        $server->on('calendarObjectChange',     [$this, 'calendarObjectChange']);
+        $server->on('beforeUnbind',             [$this, 'beforeUnbind']);
+        $server->on('schedule',                 [$this, 'scheduleLocalDelivery']);
+        $server->on('getSupportedPrivilegeSet', [$this, 'getSupportedPrivilegeSet']);
 
         $ns = '{' . self::NS_CALDAV . '}';
 
@@ -215,7 +218,7 @@ class Plugin extends ServerPlugin {
                 }
                 $outboxPath = $calendarHomePath . '/outbox/';
 
-                return new Href($outboxPath);
+                return new LocalHref($outboxPath);
 
             });
             // schedule-inbox-URL property
@@ -227,7 +230,7 @@ class Plugin extends ServerPlugin {
                 }
                 $inboxPath = $calendarHomePath . '/inbox/';
 
-                return new Href($inboxPath);
+                return new LocalHref($inboxPath);
 
             });
 
@@ -245,18 +248,28 @@ class Plugin extends ServerPlugin {
 
                 $result = $this->server->getPropertiesForPath($calendarHomePath, [
                     '{DAV:}resourcetype',
+                    '{DAV:}share-access',
                     $sccs,
                 ], 1);
 
                 foreach ($result as $child) {
-                    if (!isset($child[200]['{DAV:}resourcetype']) || !$child[200]['{DAV:}resourcetype']->is('{' . self::NS_CALDAV . '}calendar') || $child[200]['{DAV:}resourcetype']->is('{http://calendarserver.org/ns/}shared')) {
-                        // Node is either not a calendar or a shared instance.
+                    if (!isset($child[200]['{DAV:}resourcetype']) || !$child[200]['{DAV:}resourcetype']->is('{' . self::NS_CALDAV . '}calendar')) {
+                        // Node is either not a calendar
                         continue;
                     }
+                    if (isset($child[200]['{DAV:}share-access'])) {
+                        $shareAccess = $child[200]['{DAV:}share-access']->getValue();
+                        if ($shareAccess !== Sharing\Plugin::ACCESS_NOTSHARED && $shareAccess !== Sharing\Plugin::ACCESS_SHAREDOWNER) {
+                            // Node is a shared node, not owned by the relevant
+                            // user.
+                            continue;
+                        }
+
+                    }
                     if (!isset($child[200][$sccs]) || in_array('VEVENT', $child[200][$sccs]->getValue())) {
                         // Either there is no supported-calendar-component-set
                         // (which is fine) or we found one that supports VEVENT.
-                        return new Href($child['href']);
+                        return new LocalHref($child['href']);
                     }
                 }
 
@@ -492,7 +505,7 @@ class Plugin extends ServerPlugin {
         }
 
         if (!$aclPlugin->checkPrivileges($inboxPath, $caldavNS . $privilege, DAVACL\Plugin::R_PARENT, false)) {
-            $iTipMessage->scheduleStatus = '3.8;organizer did not have the ' . $privilege . ' privilege on the attendees inbox';
+            $iTipMessage->scheduleStatus = '3.8;insufficient privileges: ' . $privilege . ' is required on the recipient schedule inbox.';
             return;
         }
 
@@ -561,6 +574,65 @@ class Plugin extends ServerPlugin {
     }
 
     /**
+     * This method is triggered whenever a subsystem requests the privileges
+     * that are supported on a particular node.
+     *
+     * We need to add a number of privileges for scheduling purposes.
+     *
+     * @param INode $node
+     * @param array $supportedPrivilegeSet
+     */
+    function getSupportedPrivilegeSet(INode $node, array &$supportedPrivilegeSet) {
+
+        $ns = '{' . self::NS_CALDAV . '}';
+        if ($node instanceof IOutbox) {
+            $supportedPrivilegeSet[$ns . 'schedule-send'] = [
+                'abstract'   => false,
+                'aggregates' => [
+                    $ns . 'schedule-send-invite' => [
+                        'abstract'   => false,
+                        'aggregates' => [],
+                    ],
+                    $ns . 'schedule-send-reply' => [
+                        'abstract'   => false,
+                        'aggregates' => [],
+                    ],
+                    $ns . 'schedule-send-freebusy' => [
+                        'abstract'   => false,
+                        'aggregates' => [],
+                    ],
+                    // Privilege from an earlier scheduling draft, but still
+                    // used by some clients.
+                    $ns . 'schedule-post-vevent' => [
+                        'abstract'   => false,
+                        'aggregates' => [],
+                    ],
+                ]
+            ];
+        }
+        if ($node instanceof IInbox) {
+            $supportedPrivilegeSet[$ns . 'schedule-deliver'] = [
+                'abstract'   => false,
+                'aggregates' => [
+                    $ns . 'schedule-deliver-invite' => [
+                        'abstract'   => false,
+                        'aggregates' => [],
+                    ],
+                    $ns . 'schedule-deliver-reply' => [
+                        'abstract'   => false,
+                        'aggregates' => [],
+                    ],
+                    $ns . 'schedule-query-freebusy' => [
+                        'abstract'   => false,
+                        'aggregates' => [],
+                    ],
+                ]
+            ];
+        }
+
+    }
+
+    /**
      * This method looks at an old iCalendar object, a new iCalendar object and
      * starts sending scheduling messages based on the changes.
      *
@@ -647,7 +719,7 @@ class Plugin extends ServerPlugin {
     /**
      * This method handles POST requests to the schedule-outbox.
      *
-     * Currently, two types of requests are support:
+     * Currently, two types of requests are supported:
      *   * FREEBUSY requests from RFC 6638
      *   * Simple iTIP messages from draft-desruisseaux-caldav-sched-04
      *
@@ -699,7 +771,7 @@ class Plugin extends ServerPlugin {
 
         if ($componentType === 'VFREEBUSY' && $method === 'REQUEST') {
 
-            $acl && $acl->checkPrivileges($outboxPath, '{' . self::NS_CALDAV . '}schedule-query-freebusy');
+            $acl && $acl->checkPrivileges($outboxPath, '{' . self::NS_CALDAV . '}schedule-send-freebusy');
             $this->handleFreeBusyRequest($outboxNode, $vObject, $request, $response);
 
             // Destroy circular references so PHP can GC the object.
@@ -727,7 +799,7 @@ class Plugin extends ServerPlugin {
     protected function handleFreeBusyRequest(IOutbox $outbox, VObject\Component $vObject, RequestInterface $request, ResponseInterface $response) {
 
         $vFreeBusy = $vObject->VFREEBUSY;
-        $organizer = $vFreeBusy->organizer;
+        $organizer = $vFreeBusy->ORGANIZER;
 
         $organizer = (string)$organizer;
 
@@ -863,6 +935,9 @@ class Plugin extends ServerPlugin {
         $homeSet = $result[0][200][$caldavNS . 'calendar-home-set']->getHref();
         $inboxUrl = $result[0][200][$caldavNS . 'schedule-inbox-URL']->getHref();
 
+        // Do we have permission?
+        $aclPlugin->checkPrivileges($inboxUrl, $caldavNS . 'schedule-query-freebusy');
+
         // Grabbing the calendar list
         $objects = [];
         $calendarTimeZone = new DateTimeZone('UTC');
@@ -882,8 +957,6 @@ class Plugin extends ServerPlugin {
                 continue;
             }
 
-            $aclPlugin->checkPrivileges($homeSet . $node->getName(), $caldavNS . 'read-free-busy');
-
             if (isset($props[$ctz])) {
                 $vtimezoneObj = VObject\Reader::read($props[$ctz]);
                 $calendarTimeZone = $vtimezoneObj->VTIMEZONE->getTimeZone();
diff --git a/vendor/sabre/dav/lib/CalDAV/Schedule/SchedulingObject.php b/vendor/sabre/dav/lib/CalDAV/Schedule/SchedulingObject.php
index a36646e6c..6d9d3d5ec 100644
--- a/vendor/sabre/dav/lib/CalDAV/Schedule/SchedulingObject.php
+++ b/vendor/sabre/dav/lib/CalDAV/Schedule/SchedulingObject.php
@@ -134,22 +134,12 @@ class SchedulingObject extends \Sabre\CalDAV\CalendarObject implements IScheduli
         // The default ACL
         return [
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->objectData['principaluri'],
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
-                'principal' => $this->objectData['principaluri'],
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->objectData['principaluri'] . '/calendar-proxy-write',
+                'privilege' => '{DAV:}all',
+                'principal' => '{DAV:}owner',
                 'protected' => true,
             ],
             [
-                'privilege' => '{DAV:}write',
+                'privilege' => '{DAV:}all',
                 'principal' => $this->objectData['principaluri'] . '/calendar-proxy-write',
                 'protected' => true,
             ],
diff --git a/vendor/sabre/dav/lib/CalDAV/ShareableCalendar.php b/vendor/sabre/dav/lib/CalDAV/ShareableCalendar.php
index c11695d5f..c81c96300 100644
--- a/vendor/sabre/dav/lib/CalDAV/ShareableCalendar.php
+++ b/vendor/sabre/dav/lib/CalDAV/ShareableCalendar.php
@@ -6,7 +6,7 @@ namespace Sabre\CalDAV;
  * This object represents a CalDAV calendar that can be shared with other
  * users.
  *
- * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @copyright Copyright (C) 2007-2015 fruux GmbH (https://fruux.com/).
  * @author Evert Pot (http://evertpot.com/)
  * @license http://sabre.io/license/ Modified BSD License
  */
diff --git a/vendor/sabre/dav/lib/CalDAV/SharedCalendar.php b/vendor/sabre/dav/lib/CalDAV/SharedCalendar.php
index 7973eff9c..7a77616e3 100644
--- a/vendor/sabre/dav/lib/CalDAV/SharedCalendar.php
+++ b/vendor/sabre/dav/lib/CalDAV/SharedCalendar.php
@@ -2,6 +2,8 @@
 
 namespace Sabre\CalDAV;
 
+use Sabre\DAV\Sharing\Plugin as SPlugin;
+
 /**
  * This object represents a CalDAV calendar that is shared by a different user.
  *
@@ -12,50 +14,84 @@ namespace Sabre\CalDAV;
 class SharedCalendar extends Calendar implements ISharedCalendar {
 
     /**
-     * Constructor
+     * Returns the 'access level' for the instance of this shared resource.
+     *
+     * The value should be one of the Sabre\DAV\Sharing\Plugin::ACCESS_
+     * constants.
      *
-     * @param Backend\BackendInterface $caldavBackend
-     * @param array $calendarInfo
+     * @return int
      */
-    function __construct(Backend\BackendInterface $caldavBackend, $calendarInfo) {
-
-        $required = [
-            '{http://calendarserver.org/ns/}shared-url',
-            '{http://sabredav.org/ns}owner-principal',
-            '{http://sabredav.org/ns}read-only',
-        ];
-        foreach ($required as $r) {
-            if (!isset($calendarInfo[$r])) {
-                throw new \InvalidArgumentException('The ' . $r . ' property must be specified for SharedCalendar(s)');
-            }
-        }
+    function getShareAccess() {
 
-        parent::__construct($caldavBackend, $calendarInfo);
+        return isset($this->calendarInfo['share-access']) ? $this->calendarInfo['share-access'] : SPlugin::ACCESS_NOTSHARED;
 
     }
 
     /**
-     * This method should return the url of the owners' copy of the shared
-     * calendar.
+     * This function must return a URI that uniquely identifies the shared
+     * resource. This URI should be identical across instances, and is
+     * also used in several other XML bodies to connect invites to
+     * resources.
+     *
+     * This may simply be a relative reference to the original shared instance,
+     * but it could also be a urn. As long as it's a valid URI and unique.
      *
      * @return string
      */
-    function getSharedUrl() {
+    function getShareResourceUri() {
+
+        return $this->calendarInfo['share-resource-uri'];
+
+    }
+
+    /**
+     * Updates the list of sharees.
+     *
+     * Every item must be a Sharee object.
+     *
+     * @param \Sabre\DAV\Xml\Element\Sharee[] $sharees
+     * @return void
+     */
+    function updateInvites(array $sharees) {
 
-        return $this->calendarInfo['{http://calendarserver.org/ns/}shared-url'];
+        $this->caldavBackend->updateInvites($this->calendarInfo['id'], $sharees);
 
     }
 
     /**
-     * Returns the owner principal
+     * Returns the list of people whom this resource is shared with.
+     *
+     * Every item in the returned array must be a Sharee object with
+     * at least the following properties set:
+     *
+     * * $href
+     * * $shareAccess
+     * * $inviteStatus
      *
-     * This must be a url to a principal, or null if there's no owner
+     * and optionally:
      *
-     * @return string|null
+     * * $properties
+     *
+     * @return \Sabre\DAV\Xml\Element\Sharee[]
      */
-    function getOwner() {
+    function getInvites() {
 
-        return $this->calendarInfo['{http://sabredav.org/ns}owner-principal'];
+        return $this->caldavBackend->getInvites($this->calendarInfo['id']);
+
+    }
+
+    /**
+     * Marks this calendar as published.
+     *
+     * Publishing a calendar should automatically create a read-only, public,
+     * subscribable calendar.
+     *
+     * @param bool $value
+     * @return void
+     */
+    function setPublishStatus($value) {
+
+        $this->caldavBackend->setPublishStatus($this->calendarInfo['id'], $value);
 
     }
 
@@ -73,32 +109,72 @@ class SharedCalendar extends Calendar implements ISharedCalendar {
      */
     function getACL() {
 
-        // The top-level ACL only contains access information for the true
-        // owner of the calendar, so we need to add the information for the
-        // sharee.
-        $acl = parent::getACL();
-        $acl[] = [
-            'privilege' => '{DAV:}read',
-            'principal' => $this->calendarInfo['principaluri'],
-            'protected' => true,
-        ];
-        if ($this->calendarInfo['{http://sabredav.org/ns}read-only']) {
-            $acl[] = [
-                'privilege' => '{DAV:}write-properties',
-                'principal' => $this->calendarInfo['principaluri'],
-                'protected' => true,
-            ];
-        } else {
-            $acl[] = [
-                'privilege' => '{DAV:}write',
-                'principal' => $this->calendarInfo['principaluri'],
-                'protected' => true,
-            ];
+        $acl = [];
+
+        switch ($this->getShareAccess()) {
+            case SPlugin::ACCESS_NOTSHARED :
+            case SPlugin::ACCESS_SHAREDOWNER :
+                $acl[] = [
+                    'privilege' => '{DAV:}share',
+                    'principal' => $this->calendarInfo['principaluri'],
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}share',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
+                    'protected' => true,
+                ];
+                // No break intentional!
+            case SPlugin::ACCESS_READWRITE :
+                $acl[] = [
+                    'privilege' => '{DAV:}write',
+                    'principal' => $this->calendarInfo['principaluri'],
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}write',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
+                    'protected' => true,
+                ];
+                // No break intentional!
+            case SPlugin::ACCESS_READ :
+                $acl[] = [
+                    'privilege' => '{DAV:}write-properties',
+                    'principal' => $this->calendarInfo['principaluri'],
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}write-properties',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}read',
+                    'principal' => $this->calendarInfo['principaluri'],
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}read',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-read',
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}read',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{' . Plugin::NS_CALDAV . '}read-free-busy',
+                    'principal' => '{DAV:}authenticated',
+                    'protected' => true,
+                ];
+                break;
         }
         return $acl;
 
     }
 
+
     /**
      * This method returns the ACL's for calendar objects in this calendar.
      * The result of this method automatically gets passed to the
@@ -108,40 +184,45 @@ class SharedCalendar extends Calendar implements ISharedCalendar {
      */
     function getChildACL() {
 
-        $acl = parent::getChildACL();
-        $acl[] = [
-            'privilege' => '{DAV:}read',
-            'principal' => $this->calendarInfo['principaluri'],
-            'protected' => true,
-        ];
-
-        if (!$this->calendarInfo['{http://sabredav.org/ns}read-only']) {
-            $acl[] = [
-                'privilege' => '{DAV:}write',
-                'principal' => $this->calendarInfo['principaluri'],
-                'protected' => true,
-            ];
+        $acl = [];
+
+        switch ($this->getShareAccess()) {
+            case SPlugin::ACCESS_NOTSHARED :
+                // No break intentional
+            case SPlugin::ACCESS_SHAREDOWNER :
+                // No break intentional
+            case SPlugin::ACCESS_READWRITE:
+                $acl[] = [
+                    'privilege' => '{DAV:}write',
+                    'principal' => $this->calendarInfo['principaluri'],
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}write',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
+                    'protected' => true,
+                ];
+                // No break intentional
+            case SPlugin::ACCESS_READ:
+                $acl[] = [
+                    'privilege' => '{DAV:}read',
+                    'principal' => $this->calendarInfo['principaluri'],
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}read',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-write',
+                    'protected' => true,
+                ];
+                $acl[] = [
+                    'privilege' => '{DAV:}read',
+                    'principal' => $this->calendarInfo['principaluri'] . '/calendar-proxy-read',
+                    'protected' => true,
+                ];
+                break;
         }
-        return $acl;
-
-    }
 
-
-    /**
-     * Returns the list of people whom this calendar is shared with.
-     *
-     * Every element in this array should have the following properties:
-     *   * href - Often a mailto: address
-     *   * commonName - Optional, for example a first + last name
-     *   * status - See the Sabre\CalDAV\SharingPlugin::STATUS_ constants.
-     *   * readOnly - boolean
-     *   * summary - Optional, a description for the share
-     *
-     * @return array
-     */
-    function getShares() {
-
-        return $this->caldavBackend->getShares($this->calendarInfo['id']);
+        return $acl;
 
     }
 
diff --git a/vendor/sabre/dav/lib/CalDAV/SharingPlugin.php b/vendor/sabre/dav/lib/CalDAV/SharingPlugin.php
index 5154fb1de..6f7df02bc 100644
--- a/vendor/sabre/dav/lib/CalDAV/SharingPlugin.php
+++ b/vendor/sabre/dav/lib/CalDAV/SharingPlugin.php
@@ -4,6 +4,7 @@ namespace Sabre\CalDAV;
 
 use Sabre\DAV;
 use Sabre\DAV\Xml\Property\Href;
+use Sabre\DAV\Xml\Property\LocalHref;
 use Sabre\HTTP\RequestInterface;
 use Sabre\HTTP\ResponseInterface;
 
@@ -26,15 +27,6 @@ use Sabre\HTTP\ResponseInterface;
 class SharingPlugin extends DAV\ServerPlugin {
 
     /**
-     * These are the various status constants used by sharing-messages.
-     */
-    const STATUS_ACCEPTED = 1;
-    const STATUS_DECLINED = 2;
-    const STATUS_DELETED = 3;
-    const STATUS_NORESPONSE = 4;
-    const STATUS_INVALID = 5;
-
-    /**
      * Reference to SabreDAV server object.
      *
      * @var Sabre\DAV\Server
@@ -83,7 +75,10 @@ class SharingPlugin extends DAV\ServerPlugin {
     function initialize(DAV\Server $server) {
 
         $this->server = $server;
-        $server->resourceTypeMapping['Sabre\\CalDAV\\ISharedCalendar'] = '{' . Plugin::NS_CALENDARSERVER . '}shared';
+
+        if (is_null($this->server->getPlugin('sharing'))) {
+            throw new \LogicException('The generic "sharing" plugin must be loaded before the caldav sharing plugin. Call $server->addPlugin(new \Sabre\DAV\Sharing\Plugin()); before this one.');
+        }
 
         array_push(
             $this->server->protectedProperties,
@@ -114,24 +109,8 @@ class SharingPlugin extends DAV\ServerPlugin {
      */
     function propFindEarly(DAV\PropFind $propFind, DAV\INode $node) {
 
-        if ($node instanceof IShareableCalendar) {
-
-            $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}invite', function() use ($node) {
-                return new Xml\Property\Invite(
-                    $node->getShares()
-                );
-            });
-
-        }
-
         if ($node instanceof ISharedCalendar) {
 
-            $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}shared-url', function() use ($node) {
-                return new Href(
-                    $node->getSharedUrl()
-                );
-            });
-
             $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}invite', function() use ($node) {
 
                 // Fetching owner information
@@ -158,7 +137,7 @@ class SharingPlugin extends DAV\ServerPlugin {
                 }
 
                 return new Xml\Property\Invite(
-                    $node->getShares(),
+                    $node->getInvites(),
                     $ownerInfo
                 );
 
@@ -179,10 +158,18 @@ class SharingPlugin extends DAV\ServerPlugin {
      */
     function propFindLate(DAV\PropFind $propFind, DAV\INode $node) {
 
-        if ($node instanceof IShareableCalendar) {
+        if ($node instanceof ISharedCalendar) {
+            $shareAccess = $node->getShareAccess();
             if ($rt = $propFind->get('{DAV:}resourcetype')) {
-                if (count($node->getShares()) > 0) {
-                    $rt->add('{' . Plugin::NS_CALENDARSERVER . '}shared-owner');
+                switch ($shareAccess) {
+                    case \Sabre\DAV\Sharing\Plugin::ACCESS_SHAREDOWNER :
+                        $rt->add('{' . Plugin::NS_CALENDARSERVER . '}shared-owner');
+                        break;
+                    case \Sabre\DAV\Sharing\Plugin::ACCESS_READ :
+                    case \Sabre\DAV\Sharing\Plugin::ACCESS_READWRITE :
+                        $rt->add('{' . Plugin::NS_CALENDARSERVER . '}shared');
+                        break;
+
                 }
             }
             $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}allowed-sharing-modes', function() {
@@ -211,21 +198,24 @@ class SharingPlugin extends DAV\ServerPlugin {
     function propPatch($path, DAV\PropPatch $propPatch) {
 
         $node = $this->server->tree->getNodeForPath($path);
-        if (!$node instanceof IShareableCalendar)
+        if (!$node instanceof ISharedCalendar)
             return;
 
-        $propPatch->handle('{DAV:}resourcetype', function($value) use ($node) {
-            if ($value->is('{' . Plugin::NS_CALENDARSERVER . '}shared-owner')) return false;
-            $shares = $node->getShares();
-            $remove = [];
-            foreach ($shares as $share) {
-                $remove[] = $share['href'];
-            }
-            $node->updateShares([], $remove);
+        if ($node->getShareAccess() === \Sabre\DAV\Sharing\Plugin::ACCESS_SHAREDOWNER || $node->getShareAccess() === \Sabre\DAV\Sharing\Plugin::ACCESS_NOTSHARED) {
 
-            return true;
+            $propPatch->handle('{DAV:}resourcetype', function($value) use ($node) {
+                if ($value->is('{' . Plugin::NS_CALENDARSERVER . '}shared-owner')) return false;
+                $shares = $node->getInvites();
+                foreach ($shares as $share) {
+                    $share->access = DAV\Sharing\Plugin::ACCESS_NOACCESS;
+                }
+                $node->updateInvites($shares);
 
-        });
+                return true;
+
+            });
+
+        }
 
     }
 
@@ -267,26 +257,12 @@ class SharingPlugin extends DAV\ServerPlugin {
 
         switch ($documentType) {
 
-            // Dealing with the 'share' document, which modified invitees on a
-            // calendar.
+            // Both the DAV:share-resource and CALENDARSERVER:share requests
+            // behave identically.
             case '{' . Plugin::NS_CALENDARSERVER . '}share' :
 
-                // We can only deal with IShareableCalendar objects
-                if (!$node instanceof IShareableCalendar) {
-                    return;
-                }
-
-                $this->server->transactionType = 'post-calendar-share';
-
-                // Getting ACL info
-                $acl = $this->server->getPlugin('acl');
-
-                // If there's no ACL support, we allow everything
-                if ($acl) {
-                    $acl->checkPrivileges($path, '{DAV:}write');
-                }
-
-                $node->updateShares($message->set, $message->remove);
+                $sharingPlugin = $this->server->getPlugin('sharing');
+                $sharingPlugin->shareResource($path, $message->sharees);
 
                 $response->setStatus(200);
                 // Adding this because sending a response body may cause issues,
@@ -328,11 +304,11 @@ class SharingPlugin extends DAV\ServerPlugin {
                 $response->setHeader('X-Sabre-Status', 'everything-went-well');
 
                 if ($url) {
-                    $writer = $this->server->xml->getWriter($this->server->getBaseUri());
+                    $writer = $this->server->xml->getWriter();
                     $writer->openMemory();
                     $writer->startDocument();
                     $writer->startElement('{' . Plugin::NS_CALENDARSERVER . '}shared-as');
-                    $writer->write(new Href($url));
+                    $writer->write(new LocalHref($url));
                     $writer->endElement();
                     $response->setHeader('Content-Type', 'application/xml');
                     $response->setBody($writer->outputMemory());
@@ -345,7 +321,7 @@ class SharingPlugin extends DAV\ServerPlugin {
             case '{' . Plugin::NS_CALENDARSERVER . '}publish-calendar' :
 
                 // We can only deal with IShareableCalendar objects
-                if (!$node instanceof IShareableCalendar) {
+                if (!$node instanceof ISharedCalendar) {
                     return;
                 }
                 $this->server->transactionType = 'post-publish-calendar';
@@ -355,7 +331,7 @@ class SharingPlugin extends DAV\ServerPlugin {
 
                 // If there's no ACL support, we allow everything
                 if ($acl) {
-                    $acl->checkPrivileges($path, '{DAV:}write');
+                    $acl->checkPrivileges($path, '{DAV:}share');
                 }
 
                 $node->setPublishStatus(true);
@@ -373,7 +349,7 @@ class SharingPlugin extends DAV\ServerPlugin {
             case '{' . Plugin::NS_CALENDARSERVER . '}unpublish-calendar' :
 
                 // We can only deal with IShareableCalendar objects
-                if (!$node instanceof IShareableCalendar) {
+                if (!$node instanceof ISharedCalendar) {
                     return;
                 }
                 $this->server->transactionType = 'post-unpublish-calendar';
@@ -383,7 +359,7 @@ class SharingPlugin extends DAV\ServerPlugin {
 
                 // If there's no ACL support, we allow everything
                 if ($acl) {
-                    $acl->checkPrivileges($path, '{DAV:}write');
+                    $acl->checkPrivileges($path, '{DAV:}share');
                 }
 
                 $node->setPublishStatus(false);
diff --git a/vendor/sabre/dav/lib/CalDAV/Subscriptions/Subscription.php b/vendor/sabre/dav/lib/CalDAV/Subscriptions/Subscription.php
index ee53da2c6..3bb3451f3 100644
--- a/vendor/sabre/dav/lib/CalDAV/Subscriptions/Subscription.php
+++ b/vendor/sabre/dav/lib/CalDAV/Subscriptions/Subscription.php
@@ -5,8 +5,8 @@ namespace Sabre\CalDAV\Subscriptions;
 use Sabre\DAV\Collection;
 use Sabre\DAV\Xml\Property\Href;
 use Sabre\DAV\PropPatch;
-use Sabre\DAV\Exception\MethodNotAllowed;
 use Sabre\DAVACL\IACL;
+use Sabre\DAVACL\ACLTrait;
 use Sabre\CalDAV\Backend\SubscriptionSupport;
 
 /**
@@ -20,6 +20,8 @@ use Sabre\CalDAV\Backend\SubscriptionSupport;
  */
 class Subscription extends Collection implements ISubscription, IACL {
 
+    use ACLTrait;
+
     /**
      * caldavBackend
      *
@@ -144,7 +146,7 @@ class Subscription extends Collection implements ISubscription, IACL {
      * The Server class will filter out the extra.
      *
      * @param array $properties
-     * @return void
+     * @return array
      */
     function getProperties($properties) {
 
@@ -154,7 +156,7 @@ class Subscription extends Collection implements ISubscription, IACL {
 
             switch ($prop) {
                 case '{http://calendarserver.org/ns/}source' :
-                    $r[$prop] = new Href($this->subscriptionInfo['source'], false);
+                    $r[$prop] = new Href($this->subscriptionInfo['source']);
                     break;
                 default :
                     if (array_key_exists($prop, $this->subscriptionInfo)) {
@@ -183,19 +185,6 @@ class Subscription extends Collection implements ISubscription, IACL {
     }
 
     /**
-     * Returns a group principal.
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -211,22 +200,12 @@ class Subscription extends Collection implements ISubscription, IACL {
 
         return [
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->getOwner(),
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
+                'privilege' => '{DAV:}all',
                 'principal' => $this->getOwner(),
                 'protected' => true,
             ],
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->getOwner() . '/calendar-proxy-write',
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
+                'privilege' => '{DAV:}all',
                 'principal' => $this->getOwner() . '/calendar-proxy-write',
                 'protected' => true,
             ],
@@ -239,36 +218,4 @@ class Subscription extends Collection implements ISubscription, IACL {
 
     }
 
-    /**
-     * Updates the ACL.
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new MethodNotAllowed('Changing ACL is not yet supported');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See \Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/Invite.php b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/Invite.php
index 7fb022e33..1ca64f3e8 100644
--- a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/Invite.php
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/Invite.php
@@ -5,6 +5,7 @@ namespace Sabre\CalDAV\Xml\Notification;
 use Sabre\Xml\Writer;
 use Sabre\CalDAV\SharingPlugin as SharingPlugin;
 use Sabre\CalDAV;
+use Sabre\DAV;
 
 /**
  * This class represents the cs:invite-notification notification element.
@@ -210,16 +211,10 @@ class Invite implements NotificationInterface {
 
         switch ($this->type) {
 
-            case SharingPlugin::STATUS_ACCEPTED :
+            case DAV\Sharing\Plugin::INVITE_ACCEPTED :
                 $writer->writeElement($cs . 'invite-accepted');
                 break;
-            case SharingPlugin::STATUS_DECLINED :
-                $writer->writeElement($cs . 'invite-declined');
-                break;
-            case SharingPlugin::STATUS_DELETED :
-                $writer->writeElement($cs . 'invite-deleted');
-                break;
-            case SharingPlugin::STATUS_NORESPONSE :
+            case DAV\Sharing\Plugin::INVITE_NORESPONSE :
                 $writer->writeElement($cs . 'invite-noresponse');
                 break;
 
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/InviteReply.php b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/InviteReply.php
index 945323fed..51bfc178a 100644
--- a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/InviteReply.php
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/InviteReply.php
@@ -5,6 +5,7 @@ namespace Sabre\CalDAV\Xml\Notification;
 use Sabre\Xml\Writer;
 use Sabre\CalDAV;
 use Sabre\CalDAV\SharingPlugin;
+use Sabre\DAV;
 
 /**
  * This class represents the cs:invite-reply notification element.
@@ -162,10 +163,10 @@ class InviteReply implements NotificationInterface {
 
         switch ($this->type) {
 
-            case SharingPlugin::STATUS_ACCEPTED :
+            case DAV\Sharing\Plugin::INVITE_ACCEPTED :
                 $writer->writeElement($cs . 'invite-accepted');
                 break;
-            case SharingPlugin::STATUS_DECLINED :
+            case DAV\Sharing\Plugin::INVITE_DECLINED :
                 $writer->writeElement($cs . 'invite-declined');
                 break;
 
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/Invite.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/Invite.php
index 3ee053214..40ff6b936 100644
--- a/vendor/sabre/dav/lib/CalDAV/Xml/Property/Invite.php
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/Invite.php
@@ -2,11 +2,10 @@
 
 namespace Sabre\CalDAV\Xml\Property;
 
-use Sabre\Xml\Element;
-use Sabre\Xml\Reader;
+use Sabre\Xml\XmlSerializable;
 use Sabre\Xml\Writer;
 use Sabre\CalDAV\Plugin;
-use Sabre\CalDAV\SharingPlugin;
+use Sabre\DAV;
 
 /**
  * Invite property
@@ -20,53 +19,23 @@ use Sabre\CalDAV\SharingPlugin;
  * @author Evert Pot (http://evertpot.com/)
  * @license http://sabre.io/license/ Modified BSD License
  */
-class Invite implements Element {
+class Invite implements XmlSerializable {
 
     /**
      * The list of users a calendar has been shared to.
      *
-     * @var array
+     * @var Sharee[]
      */
-    protected $users;
-
-    /**
-     * The organizer contains information about the person who shared the
-     * object.
-     *
-     * @var array
-     */
-    protected $organizer;
+    protected $sharees;
 
     /**
      * Creates the property.
      *
-     * Users is an array. Each element of the array has the following
-     * properties:
-     *
-     *   * href - Often a mailto: address
-     *   * commonName - Optional, for example a first and lastname for a user.
-     *   * status - One of the SharingPlugin::STATUS_* constants.
-     *   * readOnly - true or false
-     *   * summary - Optional, description of the share
-     *
-     * The organizer key is optional to specify. It's only useful when a
-     * 'sharee' requests the sharing information.
-     *
-     * The organizer may have the following properties:
-     *   * href - Often a mailto: address.
-     *   * commonName - Optional human-readable name.
-     *   * firstName - Optional first name.
-     *   * lastName - Optional last name.
-     *
-     * If you wonder why these two structures are so different, I guess a
-     * valid answer is that the current spec is still a draft.
-     *
-     * @param array $users
+     * @param Sharee[] $sharees
      */
-    function __construct(array $users, array $organizer = null) {
+    function __construct(array $sharees) {
 
-        $this->users = $users;
-        $this->organizer = $organizer;
+        $this->sharees = $sharees;
 
     }
 
@@ -77,7 +46,7 @@ class Invite implements Element {
      */
     function getValue() {
 
-        return $this->users;
+        return $this->sharees;
 
     }
 
@@ -104,149 +73,55 @@ class Invite implements Element {
 
         $cs = '{' . Plugin::NS_CALENDARSERVER . '}';
 
-        if (!is_null($this->organizer)) {
-
-            $writer->startElement($cs . 'organizer');
-            $writer->writeElement('{DAV:}href', $this->organizer['href']);
-
-            if (isset($this->organizer['commonName']) && $this->organizer['commonName']) {
-                $writer->writeElement($cs . 'common-name', $this->organizer['commonName']);
-            }
-            if (isset($this->organizer['firstName']) && $this->organizer['firstName']) {
-                $writer->writeElement($cs . 'first-name', $this->organizer['firstName']);
-            }
-            if (isset($this->organizer['lastName']) && $this->organizer['lastName']) {
-                $writer->writeElement($cs . 'last-name', $this->organizer['lastName']);
-            }
-            $writer->endElement(); // organizer
+        foreach ($this->sharees as $sharee) {
 
-        }
-
-        foreach ($this->users as $user) {
-
-            $writer->startElement($cs . 'user');
-            $writer->writeElement('{DAV:}href', $user['href']);
-            if (isset($user['commonName']) && $user['commonName']) {
-                $writer->writeElement($cs . 'common-name', $user['commonName']);
-            }
-            switch ($user['status']) {
-
-                case SharingPlugin::STATUS_ACCEPTED :
-                    $writer->writeElement($cs . 'invite-accepted');
-                    break;
-                case SharingPlugin::STATUS_DECLINED :
-                    $writer->writeElement($cs . 'invite-declined');
-                    break;
-                case SharingPlugin::STATUS_NORESPONSE :
-                    $writer->writeElement($cs . 'invite-noresponse');
-                    break;
-                case SharingPlugin::STATUS_INVALID :
-                    $writer->writeElement($cs . 'invite-invalid');
-                    break;
-            }
-
-            $writer->startElement($cs . 'access');
-            if ($user['readOnly']) {
-                $writer->writeElement($cs . 'read');
+            if ($sharee->access === \Sabre\DAV\Sharing\Plugin::ACCESS_SHAREDOWNER) {
+                $writer->startElement($cs . 'organizer');
             } else {
-                $writer->writeElement($cs . 'read-write');
-            }
-            $writer->endElement(); // access
-
-            if (isset($user['summary']) && $user['summary']) {
-                $writer->writeElement($cs . 'summary', $user['summary']);
-            }
-
-            $writer->endElement(); //user
-
-        }
-
-    }
-
-    /**
-     * The deserialize method is called during xml parsing.
-     *
-     * This method is called statictly, this is because in theory this method
-     * may be used as a type of constructor, or factory method.
-     *
-     * Often you want to return an instance of the current class, but you are
-     * free to return other data as well.
-     *
-     * You are responsible for advancing the reader to the next element. Not
-     * doing anything will result in a never-ending loop.
-     *
-     * If you just want to skip parsing for this element altogether, you can
-     * just call $reader->next();
-     *
-     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
-     * the next element.
-     *
-     * @param Reader $reader
-     * @return mixed
-     */
-    static function xmlDeserialize(Reader $reader) {
-
-        $cs = '{' . Plugin::NS_CALENDARSERVER . '}';
-
-        $users = [];
-
-        foreach ($reader->parseInnerTree() as $elem) {
+                $writer->startElement($cs . 'user');
 
-            if ($elem['name'] !== $cs . 'user')
-                continue;
-
-            $user = [
-                'href'       => null,
-                'commonName' => null,
-                'readOnly'   => null,
-                'summary'    => null,
-                'status'     => null,
-            ];
-
-            foreach ($elem['value'] as $userElem) {
-
-                switch ($userElem['name']) {
-                    case $cs . 'invite-accepted' :
-                        $user['status'] = SharingPlugin::STATUS_ACCEPTED;
-                        break;
-                    case $cs . 'invite-declined' :
-                        $user['status'] = SharingPlugin::STATUS_DECLINED;
+                switch ($sharee->inviteStatus) {
+                    case DAV\Sharing\Plugin::INVITE_ACCEPTED :
+                        $writer->writeElement($cs . 'invite-accepted');
                         break;
-                    case $cs . 'invite-noresponse' :
-                        $user['status'] = SharingPlugin::STATUS_NORESPONSE;
+                    case DAV\Sharing\Plugin::INVITE_DECLINED :
+                        $writer->writeElement($cs . 'invite-declined');
                         break;
-                    case $cs . 'invite-invalid' :
-                        $user['status'] = SharingPlugin::STATUS_INVALID;
+                    case DAV\Sharing\Plugin::INVITE_NORESPONSE :
+                        $writer->writeElement($cs . 'invite-noresponse');
                         break;
-                    case '{DAV:}href' :
-                        $user['href'] = $userElem['value'];
+                    case DAV\Sharing\Plugin::INVITE_INVALID :
+                        $writer->writeElement($cs . 'invite-invalid');
                         break;
-                    case $cs . 'common-name' :
-                        $user['commonName'] = $userElem['value'];
-                        break;
-                    case $cs . 'access' :
-                        foreach ($userElem['value'] as $accessHref) {
-                            if ($accessHref['name'] === $cs . 'read') {
-                                $user['readOnly'] = true;
-                            }
-                        }
+                }
+
+                $writer->startElement($cs . 'access');
+                switch ($sharee->access) {
+                    case DAV\Sharing\Plugin::ACCESS_READWRITE :
+                        $writer->writeElement($cs . 'read-write');
                         break;
-                    case $cs . 'summary' :
-                        $user['summary'] = $userElem['value'];
+                    case DAV\Sharing\Plugin::ACCESS_READ :
+                        $writer->writeElement($cs . 'read');
                         break;
 
                 }
+                $writer->endElement(); // access
 
             }
-            if (!$user['status']) {
-                throw new \InvalidArgumentException('Every user must have one of cs:invite-accepted, cs:invite-declined, cs:invite-noresponse or cs:invite-invalid');
-            }
 
-            $users[] = $user;
+            $href = new \Sabre\DAV\Xml\Property\Href($sharee->href);
+            $href->xmlSerialize($writer);
 
-        }
+            if (isset($sharee->properties['{DAV:}displayname'])) {
+                $writer->writeElement($cs . 'common-name', $sharee->properties['{DAV:}displayname']);
+            }
+            if ($sharee->comment) {
+                $writer->writeElement($cs . 'summary', $sharee->comment);
+            }
+            $writer->endElement(); // organizer or user
 
-        return new self($users);
+        }
 
     }
+
 }
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/InviteReply.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/InviteReply.php
index ec627156f..2ecf6c2bb 100644
--- a/vendor/sabre/dav/lib/CalDAV/Xml/Request/InviteReply.php
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/InviteReply.php
@@ -2,12 +2,13 @@
 
 namespace Sabre\CalDAV\Xml\Request;
 
+use Sabre\CalDAV\Plugin;
+use Sabre\CalDAV\SharingPlugin;
+use Sabre\DAV;
+use Sabre\DAV\Exception\BadRequest;
 use Sabre\Xml\Reader;
 use Sabre\Xml\XmlDeserializable;
 use Sabre\Xml\Element\KeyValue;
-use Sabre\DAV\Exception\BadRequest;
-use Sabre\CalDAV\Plugin;
-use Sabre\CalDAV\SharingPlugin;
 
 /**
  * Invite-reply POST request parser
@@ -121,10 +122,10 @@ class InviteReply implements XmlDeserializable {
                     }
                     break;
                 case '{' . Plugin::NS_CALENDARSERVER . '}invite-accepted' :
-                    $status = SharingPlugin::STATUS_ACCEPTED;
+                    $status = DAV\Sharing\Plugin::INVITE_ACCEPTED;
                     break;
                 case '{' . Plugin::NS_CALENDARSERVER . '}invite-declined' :
-                    $status = SharingPlugin::STATUS_DECLINED;
+                    $status = DAV\Sharing\Plugin::INVITE_DECLINED;
                     break;
                 case '{' . Plugin::NS_CALENDARSERVER . '}in-reply-to' :
                     $inReplyTo = $value;
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/Share.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/Share.php
index dacc5dc94..b5d9a133c 100644
--- a/vendor/sabre/dav/lib/CalDAV/Xml/Request/Share.php
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/Share.php
@@ -2,9 +2,10 @@
 
 namespace Sabre\CalDAV\Xml\Request;
 
+use Sabre\CalDAV\Plugin;
+use Sabre\DAV\Xml\Element\Sharee;
 use Sabre\Xml\Reader;
 use Sabre\Xml\XmlDeserializable;
-use Sabre\CalDAV\Plugin;
 
 /**
  * Share POST request parser
@@ -20,37 +21,20 @@ use Sabre\CalDAV\Plugin;
 class Share implements XmlDeserializable {
 
     /**
-     * The list of new people added or updated.
-     *
-     * Every element has the following keys:
-     * 1. href - An email address
-     * 2. commonName - Some name
-     * 3. summary - An optional description of the share
-     * 4. readOnly - true or false
-     *
-     * @var array
-     */
-    public $set = [];
-
-    /**
-     * List of people removed from the share list.
-     *
-     * The list is a flat list of email addresses (including mailto:).
+     * The list of new people added or updated or removed from the share.
      *
-     * @var array
+     * @var Sharee[]
      */
-    public $remove = [];
+    public $sharees = [];
 
     /**
      * Constructor
      *
-     * @param array $set
-     * @param array $remove
+     * @param Sharee[] $sharees
      */
-    function __construct(array $set, array $remove) {
+    function __construct(array $sharees) {
 
-        $this->set = $set;
-        $this->remove = $remove;
+        $this->sharees = $sharees;
 
     }
 
@@ -77,13 +61,12 @@ class Share implements XmlDeserializable {
      */
     static function xmlDeserialize(Reader $reader) {
 
-        $elems = $reader->parseInnerTree([
+        $elems = $reader->parseGetElements([
             '{' . Plugin::NS_CALENDARSERVER . '}set'    => 'Sabre\\Xml\\Element\\KeyValue',
             '{' . Plugin::NS_CALENDARSERVER . '}remove' => 'Sabre\\Xml\\Element\\KeyValue',
         ]);
 
-        $set = [];
-        $remove = [];
+        $sharees = [];
 
         foreach ($elems as $elem) {
             switch ($elem['name']) {
@@ -94,22 +77,34 @@ class Share implements XmlDeserializable {
                     $sumElem = '{' . Plugin::NS_CALENDARSERVER . '}summary';
                     $commonName = '{' . Plugin::NS_CALENDARSERVER . '}common-name';
 
-                    $set[] = [
+                    $properties = [];
+                    if (isset($sharee[$commonName])) {
+                        $properties['{DAV:}displayname'] = $sharee[$commonName];
+                    }
+
+                    $access = array_key_exists('{' . Plugin::NS_CALENDARSERVER . '}read-write', $sharee)
+                        ? \Sabre\DAV\Sharing\Plugin::ACCESS_READWRITE
+                        : \Sabre\DAV\Sharing\Plugin::ACCESS_READ;
+
+                    $sharees[] = new Sharee([
                         'href'       => $sharee['{DAV:}href'],
-                        'commonName' => isset($sharee[$commonName]) ? $sharee[$commonName] : null,
-                        'summary'    => isset($sharee[$sumElem]) ? $sharee[$sumElem] : null,
-                        'readOnly'   => !array_key_exists('{' . Plugin::NS_CALENDARSERVER . '}read-write', $sharee),
-                    ];
+                        'properties' => $properties,
+                        'access'     => $access,
+                        'comment'    => isset($sharee[$sumElem]) ? $sharee[$sumElem] : null
+                    ]);
                     break;
 
                 case '{' . Plugin::NS_CALENDARSERVER . '}remove' :
-                    $remove[] = $elem['value']['{DAV:}href'];
+                    $sharees[] = new Sharee([
+                        'href'   => $elem['value']['{DAV:}href'],
+                        'access' => \Sabre\DAV\Sharing\Plugin::ACCESS_NOACCESS
+                    ]);
                     break;
 
             }
         }
 
-        return new self($set, $remove);
+        return new self($sharees);
 
     }
 
diff --git a/vendor/sabre/dav/lib/CardDAV/AddressBook.php b/vendor/sabre/dav/lib/CardDAV/AddressBook.php
index 70bec8760..6dd098618 100644
--- a/vendor/sabre/dav/lib/CardDAV/AddressBook.php
+++ b/vendor/sabre/dav/lib/CardDAV/AddressBook.php
@@ -16,6 +16,8 @@ use Sabre\DAVACL;
  */
 class AddressBook extends DAV\Collection implements IAddressBook, DAV\IProperties, DAVACL\IACL, DAV\Sync\ISyncCollection, DAV\IMultiGet {
 
+    use DAVACL\ACLTrait;
+
     /**
      * This is an array with addressbook information
      *
@@ -236,48 +238,6 @@ class AddressBook extends DAV\Collection implements IAddressBook, DAV\IPropertie
 
     }
 
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
-     * Returns a list of ACE's for this node.
-     *
-     * Each ACE has the following properties:
-     *   * 'privilege', a string such as {DAV:}read or {DAV:}write. These are
-     *     currently the only supported privileges
-     *   * 'principal', a url to the principal who owns the node
-     *   * 'protected' (optional), indicating that this ACE is not allowed to
-     *      be updated.
-     *
-     * @return array
-     */
-    function getACL() {
-
-        return [
-            [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->getOwner(),
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
-                'principal' => $this->getOwner(),
-                'protected' => true,
-            ],
-
-        ];
-
-    }
 
     /**
      * This method returns the ACL's for card nodes in this address book.
@@ -290,12 +250,7 @@ class AddressBook extends DAV\Collection implements IAddressBook, DAV\IPropertie
 
         return [
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->getOwner(),
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
+                'privilege' => '{DAV:}all',
                 'principal' => $this->getOwner(),
                 'protected' => true,
             ],
@@ -303,37 +258,6 @@ class AddressBook extends DAV\Collection implements IAddressBook, DAV\IPropertie
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('Changing ACL is not yet supported');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
 
     /**
      * This method returns the current sync-token for this collection.
diff --git a/vendor/sabre/dav/lib/CardDAV/AddressBookHome.php b/vendor/sabre/dav/lib/CardDAV/AddressBookHome.php
index ebc251832..888a44a40 100644
--- a/vendor/sabre/dav/lib/CardDAV/AddressBookHome.php
+++ b/vendor/sabre/dav/lib/CardDAV/AddressBookHome.php
@@ -18,6 +18,8 @@ use Sabre\Uri;
  */
 class AddressBookHome extends DAV\Collection implements DAV\IExtendedCollection, DAVACL\IACL {
 
+    use DAVACL\ACLTrait;
+
     /**
      * Principal uri
      *
@@ -186,78 +188,4 @@ class AddressBookHome extends DAV\Collection implements DAV\IExtendedCollection,
 
     }
 
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
-     * Returns a list of ACE's for this node.
-     *
-     * Each ACE has the following properties:
-     *   * 'privilege', a string such as {DAV:}read or {DAV:}write. These are
-     *     currently the only supported privileges
-     *   * 'principal', a url to the principal who owns the node
-     *   * 'protected' (optional), indicating that this ACE is not allowed to
-     *      be updated.
-     *
-     * @return array
-     */
-    function getACL() {
-
-        return [
-            [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->principalUri,
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
-                'principal' => $this->principalUri,
-                'protected' => true,
-            ],
-        ];
-
-    }
-
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('Changing ACL is not yet supported');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/CardDAV/Backend/BackendInterface.php b/vendor/sabre/dav/lib/CardDAV/Backend/BackendInterface.php
index b9691b906..54e42b899 100644
--- a/vendor/sabre/dav/lib/CardDAV/Backend/BackendInterface.php
+++ b/vendor/sabre/dav/lib/CardDAV/Backend/BackendInterface.php
@@ -55,12 +55,15 @@ interface BackendInterface {
     function updateAddressBook($addressBookId, \Sabre\DAV\PropPatch $propPatch);
 
     /**
-     * Creates a new address book
+     * Creates a new address book.
+     *
+     * This method should return the id of the new address book. The id can be
+     * in any format, including ints, strings, arrays or objects.
      *
      * @param string $principalUri
      * @param string $url Just the 'basename' of the url.
      * @param array $properties
-     * @return void
+     * @return mixed
      */
     function createAddressBook($principalUri, $url, array $properties);
 
diff --git a/vendor/sabre/dav/lib/CardDAV/Backend/PDO.php b/vendor/sabre/dav/lib/CardDAV/Backend/PDO.php
index 5509ddc02..7c3feff93 100644
--- a/vendor/sabre/dav/lib/CardDAV/Backend/PDO.php
+++ b/vendor/sabre/dav/lib/CardDAV/Backend/PDO.php
@@ -128,7 +128,7 @@ class PDO extends AbstractBackend implements SyncSupport {
                 } else {
                     $query .= ', ';
                 }
-                $query .= ' `' . $key . '` = :' . $key . ' ';
+                $query .= ' ' . $key . ' = :' . $key . ' ';
             }
             $query .= ' WHERE id = :addressbookid';
 
@@ -180,7 +180,9 @@ class PDO extends AbstractBackend implements SyncSupport {
         $query = 'INSERT INTO ' . $this->addressBooksTableName . ' (uri, displayname, description, principaluri, synctoken) VALUES (:uri, :displayname, :description, :principaluri, 1)';
         $stmt = $this->pdo->prepare($query);
         $stmt->execute($values);
-        return $this->pdo->lastInsertId();
+        return $this->pdo->lastInsertId(
+            $this->addressBooksTableName . '_id_seq'
+        );
 
     }
 
@@ -230,6 +232,7 @@ class PDO extends AbstractBackend implements SyncSupport {
         $result = [];
         while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
             $row['etag'] = '"' . $row['etag'] . '"';
+            $row['lastmodified'] = (int)$row['lastmodified'];
             $result[] = $row;
         }
         return $result;
@@ -258,6 +261,7 @@ class PDO extends AbstractBackend implements SyncSupport {
         if (!$result) return false;
 
         $result['etag'] = '"' . $result['etag'] . '"';
+        $result['lastmodified'] = (int)$result['lastmodified'];
         return $result;
 
     }
@@ -286,6 +290,7 @@ class PDO extends AbstractBackend implements SyncSupport {
         $result = [];
         while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
             $row['etag'] = '"' . $row['etag'] . '"';
+            $row['lastmodified'] = (int)$row['lastmodified'];
             $result[] = $row;
         }
         return $result;
diff --git a/vendor/sabre/dav/lib/CardDAV/Card.php b/vendor/sabre/dav/lib/CardDAV/Card.php
index 8da672502..0a040be6b 100644
--- a/vendor/sabre/dav/lib/CardDAV/Card.php
+++ b/vendor/sabre/dav/lib/CardDAV/Card.php
@@ -14,6 +14,8 @@ use Sabre\DAV;
  */
 class Card extends DAV\File implements ICard, DAVACL\IACL {
 
+    use DAVACL\ACLTrait;
+
     /**
      * CardDAV backend
      *
@@ -181,18 +183,6 @@ class Card extends DAV\File implements ICard, DAVACL\IACL {
 
     }
 
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
 
     /**
      * Returns a list of ACE's for this node.
@@ -215,12 +205,7 @@ class Card extends DAV\File implements ICard, DAVACL\IACL {
 
         return [
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $this->addressBookInfo['principaluri'],
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
+                'privilege' => '{DAV:}all',
                 'principal' => $this->addressBookInfo['principaluri'],
                 'protected' => true,
             ],
@@ -228,36 +213,4 @@ class Card extends DAV\File implements ICard, DAVACL\IACL {
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('Changing ACL is not yet supported');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/CardDAV/Plugin.php b/vendor/sabre/dav/lib/CardDAV/Plugin.php
index b8bded098..0507df100 100644
--- a/vendor/sabre/dav/lib/CardDAV/Plugin.php
+++ b/vendor/sabre/dav/lib/CardDAV/Plugin.php
@@ -4,7 +4,7 @@ namespace Sabre\CardDAV;
 
 use Sabre\DAV;
 use Sabre\DAV\Exception\ReportNotSupported;
-use Sabre\DAV\Xml\Property\Href;
+use Sabre\DAV\Xml\Property\LocalHref;
 use Sabre\DAVACL;
 use Sabre\HTTP;
 use Sabre\HTTP\RequestInterface;
@@ -156,11 +156,11 @@ class Plugin extends DAV\ServerPlugin {
             $path = $propFind->getPath();
 
             $propFind->handle('{' . self::NS_CARDDAV . '}addressbook-home-set', function() use ($path) {
-                return new Href($this->getAddressBookHomeForPrincipal($path) . '/');
+                return new LocalHref($this->getAddressBookHomeForPrincipal($path) . '/');
             });
 
             if ($this->directories) $propFind->handle('{' . self::NS_CARDDAV . '}directory-gateway', function() {
-                return new Href($this->directories);
+                return new LocalHref($this->directories);
             });
 
         }
@@ -334,12 +334,7 @@ class Plugin extends DAV\ServerPlugin {
             $data = stream_get_contents($data);
         }
 
-        $before = md5($data);
-
-        // Converting the data to unicode, if needed.
-        $data = DAV\StringUtil::ensureUTF8($data);
-
-        if (md5($data) !== $before) $modified = true;
+        $before = $data;
 
         try {
 
@@ -366,11 +361,56 @@ class Plugin extends DAV\ServerPlugin {
             throw new DAV\Exception\UnsupportedMediaType('This collection can only support vcard objects.');
         }
 
-        if (!isset($vobj->UID)) {
-            // No UID in vcards is invalid, but we'll just add it in anyway.
-            $vobj->add('UID', DAV\UUIDUtil::getUUID());
+        $options = VObject\Node::PROFILE_CARDDAV;
+        $prefer = $this->server->getHTTPPrefer();
+
+        if ($prefer['handling'] !== 'strict') {
+            $options |= VObject\Node::REPAIR;
+        }
+
+        $messages = $vobj->validate($options);
+
+        $highestLevel = 0;
+        $warningMessage = null;
+
+        // $messages contains a list of problems with the vcard, along with
+        // their severity.
+        foreach ($messages as $message) {
+
+            if ($message['level'] > $highestLevel) {
+                // Recording the highest reported error level.
+                $highestLevel = $message['level'];
+                $warningMessage = $message['message'];
+            }
+
+            switch ($message['level']) {
+
+                case 1 :
+                    // Level 1 means that there was a problem, but it was repaired.
+                    $modified = true;
+                    break;
+                case 2 :
+                    // Level 2 means a warning, but not critical
+                    break;
+                case 3 :
+                    // Level 3 means a critical error
+                    throw new DAV\Exception\UnsupportedMediaType('Validation error in vCard: ' . $message['message']);
+
+            }
+
+        }
+        if ($warningMessage) {
+            $this->server->httpResponse->setHeader(
+                'X-Sabre-Ew-Gross',
+                'vCard validation warning: ' . $warningMessage
+            );
+
+            // Re-serializing object.
             $data = $vobj->serialize();
-            $modified = true;
+            if (!$modified && strcmp($data, $before) !== 0) {
+                // This ensures that the system does not send an ETag back.
+                $modified = true;
+            }
         }
 
         // Destroy circular references to PHP will GC the object.
@@ -803,33 +843,49 @@ class Plugin extends DAV\ServerPlugin {
     /**
      * Converts a vcard blob to a different version, or jcard.
      *
-     * @param string $data
+     * @param string|resource $data
      * @param string $target
      * @return string
      */
     protected function convertVCard($data, $target) {
 
-        $data = VObject\Reader::read($data);
-        switch ($target) {
-            default :
-            case 'vcard3' :
-                $data = $data->convert(VObject\Document::VCARD30);
-                $newResult = $data->serialize();
-                break;
-            case 'vcard4' :
-                $data = $data->convert(VObject\Document::VCARD40);
-                $newResult = $data->serialize();
-                break;
-            case 'jcard' :
-                $data = $data->convert(VObject\Document::VCARD40);
-                $newResult = json_encode($data->jsonSerialize());
-                break;
-
+        if (is_resource($data)) {
+            $data = stream_get_contents($data);
         }
-        // Destroy circular references to PHP will GC the object.
-        $data->destroy();
+        $input = VObject\Reader::read($data);
+        $output = null;
+        try {
 
-        return $newResult;
+            switch ($target) {
+                default :
+                case 'vcard3' :
+                    if ($input->getDocumentType() === VObject\Document::VCARD30) {
+                        // Do nothing
+                        return $data;
+                    }
+                    $output = $input->convert(VObject\Document::VCARD30);
+                    return $output->serialize();
+                case 'vcard4' :
+                    if ($input->getDocumentType() === VObject\Document::VCARD40) {
+                        // Do nothing
+                        return $data;
+                    }
+                    $output = $input->convert(VObject\Document::VCARD40);
+                    return $output->serialize();
+                case 'jcard' :
+                    $output = $input->convert(VObject\Document::VCARD40);
+                    return json_encode($output);
+
+            }
+
+        } finally {
+
+            // Destroy circular references to PHP will GC the object.
+            $input->destroy();
+            if (!is_null($output)) {
+                $output->destroy();
+            }
+        }
 
     }
 
diff --git a/vendor/sabre/dav/lib/CardDAV/VCFExportPlugin.php b/vendor/sabre/dav/lib/CardDAV/VCFExportPlugin.php
index de8b3bb84..d015589ad 100644
--- a/vendor/sabre/dav/lib/CardDAV/VCFExportPlugin.php
+++ b/vendor/sabre/dav/lib/CardDAV/VCFExportPlugin.php
@@ -70,14 +70,34 @@ class VCFExportPlugin extends DAV\ServerPlugin {
             $aclPlugin->checkPrivileges($path, '{DAV:}read');
         }
 
-        $response->setHeader('Content-Type', 'text/directory');
-        $response->setStatus(200);
-
         $nodes = $this->server->getPropertiesForPath($path, [
             '{' . Plugin::NS_CARDDAV . '}address-data',
         ], 1);
 
-        $response->setBody($this->generateVCF($nodes));
+        $format = 'text/directory';
+
+        $output = null;
+        $filenameExtension = null;
+
+        switch ($format) {
+            case 'text/directory':
+                $output = $this->generateVCF($nodes);
+                $filenameExtension = '.vcf';
+                break;
+        }
+
+        $filename = preg_replace(
+            '/[^a-zA-Z0-9-_ ]/um',
+            '',
+            $node->getName()
+        );
+        $filename .= '-' . date('Y-m-d') . $filenameExtension;
+
+        $response->setHeader('Content-Disposition', 'attachment; filename="' . $filename . '"');
+        $response->setHeader('Content-Type', $format);
+
+        $response->setStatus(200);
+        $response->setBody($output);
 
         // Returning false to break the event chain
         return false;
diff --git a/vendor/sabre/dav/lib/DAV/Auth/Backend/AbstractDigest.php b/vendor/sabre/dav/lib/DAV/Auth/Backend/AbstractDigest.php
index 0251decc1..85c5f30d5 100644
--- a/vendor/sabre/dav/lib/DAV/Auth/Backend/AbstractDigest.php
+++ b/vendor/sabre/dav/lib/DAV/Auth/Backend/AbstractDigest.php
@@ -155,8 +155,14 @@ abstract class AbstractDigest implements BackendInterface {
             $response
         );
         $auth->init();
+
+        $oldStatus = $response->getStatus() ?: 200;
         $auth->requireLogin();
 
+        // Preventing the digest utility from modifying the http status code,
+        // this should be handled by the main plugin.
+        $response->setStatus($oldStatus);
+
     }
 
 }
diff --git a/vendor/sabre/dav/lib/DAV/Auth/Plugin.php b/vendor/sabre/dav/lib/DAV/Auth/Plugin.php
index 818d8a4ad..4b5f35ac3 100644
--- a/vendor/sabre/dav/lib/DAV/Auth/Plugin.php
+++ b/vendor/sabre/dav/lib/DAV/Auth/Plugin.php
@@ -4,7 +4,6 @@ namespace Sabre\DAV\Auth;
 
 use Sabre\HTTP\RequestInterface;
 use Sabre\HTTP\ResponseInterface;
-use Sabre\HTTP\URLUtil;
 use Sabre\DAV\Exception\NotAuthenticated;
 use Sabre\DAV\Server;
 use Sabre\DAV\ServerPlugin;
@@ -26,6 +25,20 @@ use Sabre\DAV\ServerPlugin;
 class Plugin extends ServerPlugin {
 
     /**
+     * By default this plugin will require that the user is authenticated,
+     * and refuse any access if the user is not authenticated.
+     *
+     * If this setting is set to false, we let the user through, whether they
+     * are authenticated or not.
+     *
+     * This is useful if you want to allow both authenticated and
+     * unauthenticated access to your server.
+     *
+     * @param bool
+     */
+    public $autoRequireLogin = true;
+
+    /**
      * authentication backends
      */
     protected $backends;
@@ -108,27 +121,6 @@ class Plugin extends ServerPlugin {
     }
 
     /**
-     * Returns the current username.
-     *
-     * This method is deprecated and is only kept for backwards compatibility
-     * purposes. Please switch to getCurrentPrincipal().
-     *
-     * @deprecated Will be removed in a future version!
-     * @return string|null
-     */
-    function getCurrentUser() {
-
-        // We just do a 'basename' on the principal to give back a sane value
-        // here.
-        list(, $userName) = URLUtil::splitPath(
-            $this->getCurrentPrincipal()
-        );
-
-        return $userName;
-
-    }
-
-    /**
      * This method is called before any HTTP method and forces users to be authenticated
      *
      * @param RequestInterface $request
@@ -154,6 +146,50 @@ class Plugin extends ServerPlugin {
             return;
 
         }
+
+        $authResult = $this->check($request, $response);
+
+        if ($authResult[0]) {
+            // Auth was successful
+            $this->currentPrincipal = $authResult[1];
+            $this->loginFailedReasons = null;
+            return;
+        }
+
+
+
+        // If we got here, it means that no authentication backend was
+        // successful in authenticating the user.
+        $this->currentPrincipal = null;
+        $this->loginFailedReasons = $authResult[1];
+
+        if ($this->autoRequireLogin) {
+            $this->challenge($request, $response);
+            throw new NotAuthenticated(implode(', ', $authResult[1]));
+        }
+
+    }
+
+    /**
+     * Checks authentication credentials, and logs the user in if possible.
+     *
+     * This method returns an array. The first item in the array is a boolean
+     * indicating if login was successful.
+     *
+     * If login was successful, the second item in the array will contain the
+     * current principal url/path of the logged in user.
+     *
+     * If login was not successful, the second item in the array will contain a
+     * an array with strings. The strings are a list of reasons why login was
+     * unsuccesful. For every auth backend there will be one reason, so usually
+     * there's just one.
+     *
+     * @param RequestInterface $request
+     * @param ResponseInterface $response
+     * @return array
+     */
+    function check(RequestInterface $request, ResponseInterface $response) {
+
         if (!$this->backends) {
             throw new \Sabre\DAV\Exception('No authentication backends were configured on this server.');
         }
@@ -172,20 +208,56 @@ class Plugin extends ServerPlugin {
             if ($result[0]) {
                 $this->currentPrincipal = $result[1];
                 // Exit early
-                return;
+                return [true, $result[1]];
             }
             $reasons[] = $result[1];
 
         }
 
-        // If we got here, it means that no authentication backend was
-        // successful in authenticating the user.
-        $this->currentPrincipal = null;
+        return [false, $reasons];
+
+    }
+
+    /**
+     * This method sends authentication challenges to the user.
+     *
+     * This method will for example cause a HTTP Basic backend to set a
+     * WWW-Authorization header, indicating to the client that it should
+     * authenticate.
+     *
+     * @param RequestInterface $request
+     * @param ResponseInterface $response
+     * @return array
+     */
+    function challenge(RequestInterface $request, ResponseInterface $response) {
 
         foreach ($this->backends as $backend) {
             $backend->challenge($request, $response);
         }
-        throw new NotAuthenticated(implode(', ', $reasons));
+
+    }
+
+    /**
+     * List of reasons why login failed for the last login operation.
+     *
+     * @var string[]|null
+     */
+    protected $loginFailedReasons;
+
+    /**
+     * Returns a list of reasons why login was unsuccessful.
+     *
+     * This method will return the login failed reasons for the last login
+     * operation. One for each auth backend.
+     *
+     * This method returns null if the last authentication attempt was
+     * successful, or if there was no authentication attempt yet.
+     *
+     * @return string[]|null
+     */
+    function getLoginFailedReasons() {
+
+        return $this->loginFailedReasons;
 
     }
 
diff --git a/vendor/sabre/dav/lib/DAV/Browser/Plugin.php b/vendor/sabre/dav/lib/DAV/Browser/Plugin.php
index 07ca6c3e5..49359a045 100644
--- a/vendor/sabre/dav/lib/DAV/Browser/Plugin.php
+++ b/vendor/sabre/dav/lib/DAV/Browser/Plugin.php
@@ -48,7 +48,7 @@ class Plugin extends DAV\ServerPlugin {
     public $uninterestingProperties = [
         '{DAV:}supportedlock',
         '{DAV:}acl-restrictions',
-        '{DAV:}supported-privilege-set',
+//        '{DAV:}supported-privilege-set',
         '{DAV:}supported-method-set',
     ];
 
@@ -112,7 +112,7 @@ class Plugin extends DAV\ServerPlugin {
         $getVars = $request->getQueryParameters();
 
         // CSP headers
-        $this->server->httpResponse->setHeader('Content-Security-Policy', "img-src 'self'; style-src 'self';");
+        $this->server->httpResponse->setHeader('Content-Security-Policy', "default-src 'none'; img-src 'self'; style-src 'self'; font-src 'self';");
 
         $sabreAction = isset($getVars['sabreAction']) ? $getVars['sabreAction'] : null;
 
@@ -354,7 +354,7 @@ class Plugin extends DAV\ServerPlugin {
 
         $output = '';
         if ($this->enablePost) {
-            $this->server->emit('onHTMLActionsPanel', [$node, &$output]);
+            $this->server->emit('onHTMLActionsPanel', [$node, &$output, $path]);
         }
 
         if ($output) {
@@ -368,7 +368,7 @@ class Plugin extends DAV\ServerPlugin {
 
         $html .= $this->generateFooter();
 
-        $this->server->httpResponse->setHeader('Content-Security-Policy', "img-src 'self'; style-src 'self';");
+        $this->server->httpResponse->setHeader('Content-Security-Policy', "default-src 'none'; img-src 'self'; style-src 'self'; font-src 'self';");
 
         return $html;
 
@@ -477,7 +477,7 @@ HTML;
 
         $version = DAV\Version::VERSION;
         return <<<HTML
-<footer>Generated by SabreDAV $version (c)2007-2015 <a href="http://sabre.io/">http://sabre.io/</a></footer>
+<footer>Generated by SabreDAV $version (c)2007-2016 <a href="http://sabre.io/">http://sabre.io/</a></footer>
 </body>
 </html>
 HTML;
@@ -493,9 +493,10 @@ HTML;
      *
      * @param DAV\INode $node
      * @param mixed $output
+     * @param string $path
      * @return void
      */
-    function htmlActionsPanel(DAV\INode $node, &$output) {
+    function htmlActionsPanel(DAV\INode $node, &$output, $path) {
 
         if (!$node instanceof DAV\ICollection)
             return;
diff --git a/vendor/sabre/dav/lib/DAV/Browser/assets/sabredav.css b/vendor/sabre/dav/lib/DAV/Browser/assets/sabredav.css
index c9ab2c74f..8869597f0 100644
--- a/vendor/sabre/dav/lib/DAV/Browser/assets/sabredav.css
+++ b/vendor/sabre/dav/lib/DAV/Browser/assets/sabredav.css
@@ -96,12 +96,12 @@ header a {
   vertical-align: middle;
   border: 0;
 }
-input, button {
+input, button, select {
     font: inherit;
     color: inherit;
 }
 
-input[type=text] {
+input[type=text], select {
   border: 1px solid #bbbbbb;
   line-height: 22px;
   padding: 5px 10px;
@@ -200,7 +200,7 @@ section table {
     line-height: 40px;
 }
 
-.actions input[type=text] {
+.actions input[type=text], select {
     width: 450px;
 }
 
diff --git a/vendor/sabre/dav/lib/DAV/Client.php b/vendor/sabre/dav/lib/DAV/Client.php
index d46b397b6..08d5d4702 100644
--- a/vendor/sabre/dav/lib/DAV/Client.php
+++ b/vendor/sabre/dav/lib/DAV/Client.php
@@ -3,6 +3,7 @@
 namespace Sabre\DAV;
 
 use Sabre\HTTP;
+use Sabre\Uri;
 
 /**
  * SabreDAV DAV client
@@ -387,20 +388,10 @@ class Client extends HTTP\Client {
      */
     function getAbsoluteUrl($url) {
 
-        // If the url starts with http:// or https://, the url is already absolute.
-        if (preg_match('/^http(s?):\/\//', $url)) {
-            return $url;
-        }
-
-        // If the url starts with a slash, we must calculate the url based off
-        // the root of the base url.
-        if (strpos($url, '/') === 0) {
-            $parts = parse_url($this->baseUri);
-            return $parts['scheme'] . '://' . $parts['host'] . (isset($parts['port']) ? ':' . $parts['port'] : '') . $url;
-        }
-
-        // Otherwise...
-        return $this->baseUri . $url;
+        return Uri\resolve(
+            $this->baseUri,
+            $url
+        );
 
     }
 
diff --git a/vendor/sabre/dav/lib/DAV/CorePlugin.php b/vendor/sabre/dav/lib/DAV/CorePlugin.php
index 3a70b2a7e..a1b052915 100644
--- a/vendor/sabre/dav/lib/DAV/CorePlugin.php
+++ b/vendor/sabre/dav/lib/DAV/CorePlugin.php
@@ -50,6 +50,8 @@ class CorePlugin extends ServerPlugin {
         $server->on('propFind',         [$this, 'propFindNode'], 120);
         $server->on('propFind',         [$this, 'propFindLate'], 200);
 
+        $server->on('exception',        [$this, 'exception']);
+
     }
 
     /**
@@ -844,10 +846,8 @@ class CorePlugin extends ServerPlugin {
         if ($node instanceof IProperties && $propertyNames = $propFind->get404Properties()) {
 
             $nodeProperties = $node->getProperties($propertyNames);
-            foreach ($propertyNames as $propertyName) {
-                if (array_key_exists($propertyName, $nodeProperties)) {
-                    $propFind->set($propertyName, $nodeProperties[$propertyName], 200);
-                }
+            foreach ($nodeProperties as $propertyName => $propertyValue) {
+                $propFind->set($propertyName, $propertyValue, 200);
             }
 
         }
@@ -905,6 +905,38 @@ class CorePlugin extends ServerPlugin {
     }
 
     /**
+     * Listens for exception events, and automatically logs them.
+     *
+     * @param Exception $e
+     */
+    function exception($e) {
+
+        $logLevel = \Psr\Log\LogLevel::CRITICAL;
+        if ($e instanceof \Sabre\DAV\Exception) {
+            // If it's a standard sabre/dav exception, it means we have a http
+            // status code available.
+            $code = $e->getHTTPCode();
+
+            if ($code >= 400 && $code < 500) {
+                // user error
+                $logLevel = \Psr\Log\LogLevel::INFO;
+            } else {
+                // Server-side error. We mark it's as an error, but it's not
+                // critical.
+                $logLevel = \Psr\Log\LogLevel::ERROR;
+            }
+        }
+
+        $this->server->getLogger()->log(
+            $logLevel,
+            'Uncaught exception',
+            [
+                'exception' => $e,
+            ]
+        );
+    }
+
+    /**
      * Returns a bunch of meta-data about the plugin.
      *
      * Providing this information is optional, and is mainly displayed by the
diff --git a/vendor/sabre/dav/lib/DAV/FS/Directory.php b/vendor/sabre/dav/lib/DAV/FS/Directory.php
index 963e5554c..362f7a411 100644
--- a/vendor/sabre/dav/lib/DAV/FS/Directory.php
+++ b/vendor/sabre/dav/lib/DAV/FS/Directory.php
@@ -140,10 +140,10 @@ class Directory extends Node implements DAV\ICollection, DAV\IQuota {
      * @return array
      */
     function getQuotaInfo() {
-
+        $absolute = realpath($this->path);
         return [
-            disk_total_space($this->path) - disk_free_space($this->path),
-            disk_free_space($this->path)
+            disk_total_space($absolute) - disk_free_space($absolute),
+            disk_free_space($absolute)
         ];
 
     }
diff --git a/vendor/sabre/dav/lib/DAV/File.php b/vendor/sabre/dav/lib/DAV/File.php
index e0a0391db..675956b22 100644
--- a/vendor/sabre/dav/lib/DAV/File.php
+++ b/vendor/sabre/dav/lib/DAV/File.php
@@ -15,12 +15,24 @@ namespace Sabre\DAV;
 abstract class File extends Node implements IFile {
 
     /**
-     * Updates the data
+     * Replaces the contents of the file.
      *
-     * data is a readable stream resource.
+     * The data argument is a readable stream resource.
      *
-     * @param resource $data
-     * @return void
+     * After a succesful put operation, you may choose to return an ETag. The
+     * etag must always be surrounded by double-quotes. These quotes must
+     * appear in the actual string you're returning.
+     *
+     * Clients may use the ETag from a PUT request to later on make sure that
+     * when they update the file, the contents haven't changed in the mean
+     * time.
+     *
+     * If you don't plan to store the file byte-by-byte, and you return a
+     * different object on a subsequent GET you are strongly recommended to not
+     * return an ETag, and just return null.
+     *
+     * @param string|resource $data
+     * @return string|null
      */
     function put($data) {
 
diff --git a/vendor/sabre/dav/lib/DAV/ICollection.php b/vendor/sabre/dav/lib/DAV/ICollection.php
index 390d9b741..7793070d3 100644
--- a/vendor/sabre/dav/lib/DAV/ICollection.php
+++ b/vendor/sabre/dav/lib/DAV/ICollection.php
@@ -54,14 +54,14 @@ interface ICollection extends INode {
      * exist.
      *
      * @param string $name
-     * @return DAV\INode
+     * @return INode
      */
     function getChild($name);
 
     /**
      * Returns an array with all the child nodes
      *
-     * @return DAV\INode[]
+     * @return INode[]
      */
     function getChildren();
 
diff --git a/vendor/sabre/dav/lib/DAV/IFile.php b/vendor/sabre/dav/lib/DAV/IFile.php
index e16a3a58a..37e7cd33c 100644
--- a/vendor/sabre/dav/lib/DAV/IFile.php
+++ b/vendor/sabre/dav/lib/DAV/IFile.php
@@ -32,7 +32,7 @@ interface IFile extends INode {
      * different object on a subsequent GET you are strongly recommended to not
      * return an ETag, and just return null.
      *
-     * @param resource $data
+     * @param resource|data $data
      * @return string|null
      */
     function put($data);
diff --git a/vendor/sabre/dav/lib/DAV/INode.php b/vendor/sabre/dav/lib/DAV/INode.php
index b5e6cb9ef..bb884934d 100644
--- a/vendor/sabre/dav/lib/DAV/INode.php
+++ b/vendor/sabre/dav/lib/DAV/INode.php
@@ -36,9 +36,10 @@ interface INode {
     function setName($name);
 
     /**
-     * Returns the last modification time, as a unix timestamp
+     * Returns the last modification time, as a unix timestamp. Return null
+     * if the information is not available.
      *
-     * @return int
+     * @return int|null
      */
     function getLastModified();
 
diff --git a/vendor/sabre/dav/lib/DAV/PropertyStorage/Backend/PDO.php b/vendor/sabre/dav/lib/DAV/PropertyStorage/Backend/PDO.php
index 910e4979d..2fe843884 100644
--- a/vendor/sabre/dav/lib/DAV/PropertyStorage/Backend/PDO.php
+++ b/vendor/sabre/dav/lib/DAV/PropertyStorage/Backend/PDO.php
@@ -88,6 +88,9 @@ class PDO implements BackendInterface {
         $stmt->execute([$path]);
 
         while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+            if (gettype($row['value']) === 'resource') {
+                $row['value'] = stream_get_contents($row['value']);
+            }
             switch ($row['valuetype']) {
                 case null :
                 case self::VT_STRING :
@@ -121,7 +124,26 @@ class PDO implements BackendInterface {
 
         $propPatch->handleRemaining(function($properties) use ($path) {
 
-            $updateStmt = $this->pdo->prepare("REPLACE INTO " . $this->tableName . " (path, name, valuetype, value) VALUES (?, ?, ?, ?)");
+
+            if ($this->pdo->getAttribute(\PDO::ATTR_DRIVER_NAME) === 'pgsql') {
+
+                $updateSql = <<<SQL
+INSERT INTO {$this->tableName} (path, name, valuetype, value)
+VALUES (:path, :name, :valuetype, :value)
+ON CONFLICT (path, name)
+DO UPDATE SET valuetype = :valuetype, value = :value
+SQL;
+
+
+            } else {
+                $updateSql = <<<SQL
+REPLACE INTO {$this->tableName} (path, name, valuetype, value)
+VALUES (:path, :name, :valuetype, :value)
+SQL;
+
+            }
+
+            $updateStmt = $this->pdo->prepare($updateSql);
             $deleteStmt = $this->pdo->prepare("DELETE FROM " . $this->tableName . " WHERE path = ? AND name = ?");
 
             foreach ($properties as $name => $value) {
@@ -136,7 +158,14 @@ class PDO implements BackendInterface {
                         $valueType = self::VT_OBJECT;
                         $value = serialize($value);
                     }
-                    $updateStmt->execute([$path, $name, $valueType, $value]);
+
+                    $updateStmt->bindParam('path', $path, \PDO::PARAM_STR);
+                    $updateStmt->bindParam('name', $name, \PDO::PARAM_STR);
+                    $updateStmt->bindParam('valuetype', $valueType, \PDO::PARAM_INT);
+                    $updateStmt->bindParam('value', $value, \PDO::PARAM_LOB);
+
+                    $updateStmt->execute();
+
                 } else {
                     $deleteStmt->execute([$path, $name]);
                 }
diff --git a/vendor/sabre/dav/lib/DAV/Server.php b/vendor/sabre/dav/lib/DAV/Server.php
index b37652812..024b7a557 100644
--- a/vendor/sabre/dav/lib/DAV/Server.php
+++ b/vendor/sabre/dav/lib/DAV/Server.php
@@ -8,6 +8,10 @@ use Sabre\HTTP\RequestInterface;
 use Sabre\HTTP\ResponseInterface;
 use Sabre\HTTP\URLUtil;
 use Sabre\Uri;
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerAwareTrait;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
 
 /**
  * Main DAV server class
@@ -16,7 +20,9 @@ use Sabre\Uri;
  * @author Evert Pot (http://evertpot.com/)
  * @license http://sabre.io/license/ Modified BSD License
  */
-class Server extends EventEmitter {
+class Server extends EventEmitter implements LoggerAwareInterface {
+
+    use LoggerAwareTrait;
 
     /**
      * Infinity is used for some request supporting the HTTP Depth header and indicates that the operation should traverse the entire tree
@@ -431,6 +437,20 @@ class Server extends EventEmitter {
     }
 
     /**
+     * Returns the PSR-3 logger objcet.
+     *
+     * @return LoggerInterface
+     */
+    function getLogger() {
+
+        if (!$this->logger) {
+            $this->logger = new NullLogger();
+        }
+        return $this->logger;
+
+    }
+
+    /**
      * Handles a http request, and execute a method based on its name
      *
      * @param RequestInterface $request
@@ -1177,9 +1197,20 @@ class Server extends EventEmitter {
 
         if (!$success) {
             $result = $mkCol->getResult();
-            // generateMkCol needs the href key to exist.
-            $result['href'] = $uri;
-            return $result;
+
+            $formattedResult = [
+                'href' => $uri,
+            ];
+
+            foreach ($result as $propertyName => $status) {
+
+                if (!isset($formattedResult[$status])) {
+                    $formattedResult[$status] = [];
+                }
+                $formattedResult[$status][$propertyName] = null;
+
+            }
+            return $formattedResult;
         }
 
         $this->tree->markDirty($parentUri);
diff --git a/vendor/sabre/dav/lib/DAV/Sharing/ISharedNode.php b/vendor/sabre/dav/lib/DAV/Sharing/ISharedNode.php
new file mode 100644
index 000000000..034aefbdc
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAV/Sharing/ISharedNode.php
@@ -0,0 +1,69 @@
+<?php
+
+namespace Sabre\DAV\Sharing;
+
+use Sabre\DAV\INode;
+
+/**
+ * This interface represents a resource that has sharing capabilities, either
+ * because it's possible for an owner to share the resource, or because this is
+ * an instance of a shared resource.
+ *
+ * @copyright Copyright (C) fruux GmbH. (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+interface ISharedNode extends INode {
+
+    /**
+     * Returns the 'access level' for the instance of this shared resource.
+     *
+     * The value should be one of the Sabre\DAV\Sharing\Plugin::ACCESS_
+     * constants.
+     *
+     * @return int
+     */
+    function getShareAccess();
+
+    /**
+     * This function must return a URI that uniquely identifies the shared
+     * resource. This URI should be identical across instances, and is
+     * also used in several other XML bodies to connect invites to
+     * resources.
+     *
+     * This may simply be a relative reference to the original shared instance,
+     * but it could also be a urn. As long as it's a valid URI and unique.
+     *
+     * @return string
+     */
+    function getShareResourceUri();
+
+    /**
+     * Updates the list of sharees.
+     *
+     * Every item must be a Sharee object.
+     *
+     * @param \Sabre\DAV\Xml\Element\Sharee[] $sharees
+     * @return void
+     */
+    function updateInvites(array $sharees);
+
+    /**
+     * Returns the list of people whom this resource is shared with.
+     *
+     * Every item in the returned array must be a Sharee object with
+     * at least the following properties set:
+     *
+     * * $href
+     * * $shareAccess
+     * * $inviteStatus
+     *
+     * and optionally:
+     *
+     * * $properties
+     *
+     * @return \Sabre\DAV\Xml\Element\Sharee[]
+     */
+    function getInvites();
+
+}
diff --git a/vendor/sabre/dav/lib/DAV/Sharing/Plugin.php b/vendor/sabre/dav/lib/DAV/Sharing/Plugin.php
new file mode 100644
index 000000000..354d06a56
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAV/Sharing/Plugin.php
@@ -0,0 +1,342 @@
+<?php
+
+namespace Sabre\DAV\Sharing;
+
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\DAV\Exception\Forbidden;
+use Sabre\DAV\INode;
+use Sabre\DAV\PropFind;
+use Sabre\DAV\Server;
+use Sabre\DAV\ServerPlugin;
+use Sabre\DAV\Xml\Property;
+use Sabre\DAV\Xml\Element\Sharee;
+use Sabre\HTTP\RequestInterface;
+use Sabre\HTTP\ResponseInterface;
+
+/**
+ * This plugin implements HTTP requests and properties related to:
+ *
+ * draft-pot-webdav-resource-sharing
+ *
+ * This specification allows people to share webdav resources with others.
+ *
+ * @copyright Copyright (C) 2007-2015 fruux GmbH. (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Plugin extends ServerPlugin {
+
+    const ACCESS_NOTSHARED = 0;
+    const ACCESS_SHAREDOWNER = 1;
+    const ACCESS_READ = 2;
+    const ACCESS_READWRITE = 3;
+    const ACCESS_NOACCESS = 4;
+
+    const INVITE_NORESPONSE = 1;
+    const INVITE_ACCEPTED = 2;
+    const INVITE_DECLINED = 3;
+    const INVITE_INVALID = 4;
+
+    /**
+     * Reference to SabreDAV server object.
+     *
+     * @var Sabre\DAV\Server
+     */
+    protected $server;
+
+    /**
+     * This method should return a list of server-features.
+     *
+     * This is for example 'versioning' and is added to the DAV: header
+     * in an OPTIONS response.
+     *
+     * @return array
+     */
+    function getFeatures() {
+
+        return ['resource-sharing'];
+
+    }
+
+    /**
+     * Returns a plugin name.
+     *
+     * Using this name other plugins will be able to access other plugins
+     * using \Sabre\DAV\Server::getPlugin
+     *
+     * @return string
+     */
+    function getPluginName() {
+
+        return 'sharing';
+
+    }
+
+    /**
+     * This initializes the plugin.
+     *
+     * This function is called by Sabre\DAV\Server, after
+     * addPlugin is called.
+     *
+     * This method should set up the required event subscriptions.
+     *
+     * @param Server $server
+     * @return void
+     */
+    function initialize(Server $server) {
+
+        $this->server = $server;
+
+        $server->xml->elementMap['{DAV:}share-resource'] = 'Sabre\\DAV\\Xml\\Request\\ShareResource';
+
+        array_push(
+            $server->protectedProperties,
+            '{DAV:}share-mode'
+        );
+
+        $server->on('method:POST',              [$this, 'httpPost']);
+        $server->on('propFind',                 [$this, 'propFind']);
+        $server->on('getSupportedPrivilegeSet', [$this, 'getSupportedPrivilegeSet']);
+        $server->on('onHTMLActionsPanel',       [$this, 'htmlActionsPanel']);
+        $server->on('onBrowserPostAction',      [$this, 'browserPostAction']);
+
+    }
+
+    /**
+     * Updates the list of sharees on a shared resource.
+     *
+     * The sharees  array is a list of people that are to be added modified
+     * or removed in the list of shares.
+     *
+     * @param string $path
+     * @param Sharee[] $sharees
+     * @return void
+     */
+    function shareResource($path, array $sharees) {
+
+        $node = $this->server->tree->getNodeForPath($path);
+
+        if (!$node instanceof ISharedNode) {
+
+            throw new Forbidden('Sharing is not allowed on this node');
+
+        }
+
+        // Getting ACL info
+        $acl = $this->server->getPlugin('acl');
+
+        // If there's no ACL support, we allow everything
+        if ($acl) {
+            $acl->checkPrivileges($path, '{DAV:}share');
+        }
+
+        foreach ($sharees as $sharee) {
+            // We're going to attempt to get a local principal uri for a share
+            // href by emitting the getPrincipalByUri event.
+            $principal = null;
+            $this->server->emit('getPrincipalByUri', [$sharee->href, &$principal]);
+            $sharee->principal = $principal;
+        }
+        $node->updateInvites($sharees);
+
+    }
+
+    /**
+     * This event is triggered when properties are requested for nodes.
+     *
+     * This allows us to inject any sharings-specific properties.
+     *
+     * @param PropFind $propFind
+     * @param INode $node
+     * @return void
+     */
+    function propFind(PropFind $propFind, INode $node) {
+
+        if ($node instanceof ISharedNode) {
+
+            $propFind->handle('{DAV:}share-access', function() use ($node) {
+
+                return new Property\ShareAccess($node->getShareAccess());
+
+            });
+            $propFind->handle('{DAV:}invite', function() use ($node) {
+
+                return new Property\Invite($node->getInvites());
+
+            });
+            $propFind->handle('{DAV:}share-resource-uri', function() use ($node) {
+
+                return new Property\Href($node->getShareResourceUri());
+
+            });
+
+        }
+
+    }
+
+    /**
+     * We intercept this to handle POST requests on shared resources
+     *
+     * @param RequestInterface $request
+     * @param ResponseInterface $response
+     * @return null|bool
+     */
+    function httpPost(RequestInterface $request, ResponseInterface $response) {
+
+        $path = $request->getPath();
+        $contentType = $request->getHeader('Content-Type');
+
+        // We're only interested in the davsharing content type.
+        if (strpos($contentType, 'application/davsharing+xml') === false) {
+            return;
+        }
+
+        $message = $this->server->xml->parse(
+            $request->getBody(),
+            $request->getUrl(),
+            $documentType
+        );
+
+        switch ($documentType) {
+
+            case '{DAV:}share-resource':
+
+                $this->shareResource($path, $message->sharees);
+                $response->setStatus(200);
+                // Adding this because sending a response body may cause issues,
+                // and I wanted some type of indicator the response was handled.
+                $response->setHeader('X-Sabre-Status', 'everything-went-well');
+
+                // Breaking the event chain
+                return false;
+
+            default :
+                throw new BadRequest('Unexpected document type: ' . $documentType . ' for this Content-Type');
+
+        }
+
+    }
+
+    /**
+     * This method is triggered whenever a subsystem reqeuests the privileges
+     * hat are supported on a particular node.
+     *
+     * We need to add a number of privileges for scheduling purposes.
+     *
+     * @param INode $node
+     * @param array $supportedPrivilegeSet
+     */
+    function getSupportedPrivilegeSet(INode $node, array &$supportedPrivilegeSet) {
+
+        if ($node instanceof ISharedNode) {
+            $supportedPrivilegeSet['{DAV:}share'] = [
+                'abstract'   => false,
+                'aggregates' => [],
+            ];
+        }
+    }
+
+    /**
+     * Returns a bunch of meta-data about the plugin.
+     *
+     * Providing this information is optional, and is mainly displayed by the
+     * Browser plugin.
+     *
+     * The description key in the returned array may contain html and will not
+     * be sanitized.
+     *
+     * @return array
+     */
+    function getPluginInfo() {
+
+        return [
+            'name'        => $this->getPluginName(),
+            'description' => 'This plugin implements WebDAV resource sharing',
+            'link'        => 'https://github.com/evert/webdav-sharing'
+        ];
+
+    }
+
+    /**
+     * This method is used to generate HTML output for the
+     * DAV\Browser\Plugin.
+     *
+     * @param INode $node
+     * @param string $output
+     * @param string $path
+     * @return bool|null
+     */
+    function htmlActionsPanel(INode $node, &$output, $path) {
+
+        if (!$node instanceof ISharedNode) {
+            return;
+        }
+
+        $aclPlugin = $this->server->getPlugin('acl');
+        if ($aclPlugin) {
+            if (!$aclPlugin->checkPrivileges($path, '{DAV:}share', \Sabre\DAVACL\Plugin::R_PARENT, false)) {
+                // Sharing is not permitted, we will not draw this interface.
+                return;
+            }
+        }
+
+        $output .= '<tr><td colspan="2"><form method="post" action="">
+            <h3>Share this resource</h3>
+            <input type="hidden" name="sabreAction" value="share" />
+            <label>Share with (uri):</label> <input type="text" name="href" placeholder="mailto:user@example.org"/><br />
+            <label>Access</label>
+                <select name="access">
+                    <option value="readwrite">Read-write</option>
+                    <option value="read">Read-only</option>
+                    <option value="no-access">Revoke access</option>
+                </select><br />
+             <input type="submit" value="share" />
+            </form>
+            </td></tr>';
+
+    }
+
+    /**
+     * This method is triggered for POST actions generated by the browser
+     * plugin.
+     *
+     * @param string $path
+     * @param string $action
+     * @param array $postVars
+     */
+    function browserPostAction($path, $action, $postVars) {
+
+        if ($action !== 'share') {
+            return;
+        }
+
+        if (empty($postVars['href'])) {
+            throw new BadRequest('The "href" POST parameter is required');
+        }
+        if (empty($postVars['access'])) {
+            throw new BadRequest('The "access" POST parameter is required');
+        }
+
+        $accessMap = [
+            'readwrite' => self::ACCESS_READWRITE,
+            'read'      => self::ACCESS_READ,
+            'no-access' => self::ACCESS_NOACCESS,
+        ];
+
+        if (!isset($accessMap[$postVars['access']])) {
+            throw new BadRequest('The "access" POST must be readwrite, read or no-access');
+        }
+        $sharee = new Sharee([
+            'href'   => $postVars['href'],
+            'access' => $accessMap[$postVars['access']],
+        ]);
+
+        $this->shareResource(
+            $path,
+            [$sharee]
+        );
+        return false;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/DAV/Tree.php b/vendor/sabre/dav/lib/DAV/Tree.php
index 4563f7c72..5d2792503 100644
--- a/vendor/sabre/dav/lib/DAV/Tree.php
+++ b/vendor/sabre/dav/lib/DAV/Tree.php
@@ -229,7 +229,7 @@ class Tree {
         // flushing the entire cache
         $path = trim($path, '/');
         foreach ($this->cache as $nodePath => $node) {
-            if ($nodePath == $path || strpos($nodePath, $path . '/') === 0)
+            if ($path === '' || $nodePath == $path || strpos($nodePath, $path . '/') === 0)
                 unset($this->cache[$nodePath]);
 
         }
diff --git a/vendor/sabre/dav/lib/DAV/Version.php b/vendor/sabre/dav/lib/DAV/Version.php
index f9331943a..5430b967c 100644
--- a/vendor/sabre/dav/lib/DAV/Version.php
+++ b/vendor/sabre/dav/lib/DAV/Version.php
@@ -14,6 +14,6 @@ class Version {
     /**
      * Full version number
      */
-    const VERSION = '3.1.3';
+    const VERSION = '3.2.0-beta1';
 
 }
diff --git a/vendor/sabre/dav/lib/DAV/Xml/Element/Sharee.php b/vendor/sabre/dav/lib/DAV/Xml/Element/Sharee.php
new file mode 100644
index 000000000..dcfd7bd2e
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAV/Xml/Element/Sharee.php
@@ -0,0 +1,199 @@
+<?php
+
+namespace Sabre\DAV\Xml\Element;
+
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\DAV\Sharing\Plugin;
+use Sabre\DAV\Xml\Property\Href;
+use Sabre\DAV\Xml\Property\ShareAccess;
+use Sabre\Xml\Deserializer;
+use Sabre\Xml\Element;
+use Sabre\Xml\Reader;
+use Sabre\Xml\Writer;
+
+/**
+ * This class represents the {DAV:}sharee element.
+ *
+ * @copyright Copyright (C) fruux GmbH. (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Sharee implements Element {
+
+    /**
+     * A URL. Usually a mailto: address, could also be a principal url.
+     * This uniquely identifies the sharee.
+     *
+     * @var string
+     */
+    public $href;
+
+    /**
+     * A local principal path. The server will do its best to locate the
+     * principal uri based on the given uri. If we could find a local matching
+     * principal uri, this property will contain the value.
+     *
+     * @var string|null
+     */
+    public $principal;
+
+    /**
+     * A list of WebDAV properties that describe the sharee. This might for
+     * example contain a {DAV:}displayname with the real name of the user.
+     *
+     * @var array
+     */
+    public $properties = [];
+
+    /**
+     * Share access level. One of the Sabre\DAV\Sharing\Plugin::ACCESS
+     * constants.
+     *
+     * Can be one of:
+     *
+     * ACCESS_READ
+     * ACCESS_READWRITE
+     * ACCESS_SHAREDOWNER
+     * ACCESS_NOACCESS
+     *
+     * depending on context.
+     *
+     * @var int
+     */
+    public $access;
+
+    /**
+     * When a sharee is originally invited to a share, the sharer may add
+     * a comment. This will be placed in this property.
+     *
+     * @var string
+     */
+    public $comment;
+
+    /**
+     * The status of the invite, should be one of the
+     * Sabre\DAV\Sharing\Plugin::INVITE constants.
+     *
+     * @var int
+     */
+    public $inviteStatus;
+
+    /**
+     * Creates the object
+     *
+     * $properties will be used to populate all internal properties.
+     *
+     * @param array $properties
+     */
+    function __construct(array $properties = []) {
+
+        foreach ($properties as $k => $v) {
+
+            if (property_exists($this, $k)) {
+                $this->$k = $v;
+            } else {
+                throw new \InvalidArgumentException('Unknown property: ' . $k);
+            }
+
+        }
+
+    }
+
+    /**
+     * The xmlSerialize method is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+
+        $writer->write([
+            new Href($this->href),
+            '{DAV:}prop'         => $this->properties,
+            '{DAV:}share-access' => new ShareAccess($this->access),
+        ]);
+        switch ($this->inviteStatus) {
+            case Plugin::INVITE_NORESPONSE :
+                $writer->writeElement('{DAV:}invite-noresponse');
+                break;
+            case Plugin::INVITE_ACCEPTED :
+                $writer->writeElement('{DAV:}invite-accepted');
+                break;
+            case Plugin::INVITE_DECLINED :
+                $writer->writeElement('{DAV:}invite-declined');
+                break;
+            case Plugin::INVITE_INVALID :
+                $writer->writeElement('{DAV:}invite-invalid');
+                break;
+        }
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        // Temporarily override configuration
+        $reader->pushContext();
+        $reader->elementMap['{DAV:}share-access'] = 'Sabre\DAV\Xml\Property\ShareAccess';
+        $reader->elementMap['{DAV:}prop'] = 'Sabre\Xml\Deserializer\keyValue';
+
+        $elems = Deserializer\keyValue($reader, 'DAV:');
+
+        // Restore previous configuration
+        $reader->popContext();
+
+        $sharee = new self();
+        if (!isset($elems['href'])) {
+            throw new BadRequest('Every {DAV:}sharee must have a {DAV:}href child-element');
+        }
+        $sharee->href = $elems['href'];
+
+        if (isset($elems['prop'])) {
+            $sharee->properties = $elems['prop'];
+        }
+        if (isset($elems['comment'])) {
+            $sharee->comment = $elems['comment'];
+        }
+        if (!isset($elems['share-access'])) {
+            throw new BadRequest('Every {DAV:}sharee must have a {DAV:}share-access child element');
+        }
+        $sharee->access = $elems['share-access']->getValue();
+        return $sharee;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/DAV/Xml/Property/Href.php b/vendor/sabre/dav/lib/DAV/Xml/Property/Href.php
index 538e98d0f..0027f72e1 100644
--- a/vendor/sabre/dav/lib/DAV/Xml/Property/Href.php
+++ b/vendor/sabre/dav/lib/DAV/Xml/Property/Href.php
@@ -7,6 +7,7 @@ use Sabre\DAV\Browser\HtmlOutputHelper;
 use Sabre\Xml\Element;
 use Sabre\Xml\Reader;
 use Sabre\Xml\Writer;
+use Sabre\Uri;
 
 /**
  * Href property
@@ -32,13 +33,6 @@ class Href implements Element, HtmlOutput {
     protected $hrefs;
 
     /**
-     * Automatically prefix the url with the server base directory
-     *
-     * @var bool
-     */
-    protected $autoPrefix = true;
-
-    /**
      * Constructor
      *
      * You must either pass a string for a single href, or an array of hrefs.
@@ -47,16 +41,13 @@ class Href implements Element, HtmlOutput {
      * and not relative to the servers base uri.
      *
      * @param string|string[] $href
-     * @param bool $autoPrefix
      */
-    function __construct($hrefs, $autoPrefix = true) {
+    function __construct($hrefs) {
 
         if (is_string($hrefs)) {
             $hrefs = [$hrefs];
         }
         $this->hrefs = $hrefs;
-        $this->autoPrefix = $autoPrefix;
-
 
     }
 
@@ -104,9 +95,7 @@ class Href implements Element, HtmlOutput {
     function xmlSerialize(Writer $writer) {
 
         foreach ($this->getHrefs() as $href) {
-            if ($this->autoPrefix) {
-                $href = $writer->contextUri . \Sabre\HTTP\encodePath($href);
-            }
+            $href = Uri\resolve($writer->contextUri, $href);
             $writer->writeElement('{DAV:}href', $href);
         }
 
diff --git a/vendor/sabre/dav/lib/DAV/Xml/Property/Invite.php b/vendor/sabre/dav/lib/DAV/Xml/Property/Invite.php
new file mode 100644
index 000000000..0616ff113
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAV/Xml/Property/Invite.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Sabre\DAV\Xml\Property;
+
+use Sabre\DAV\Sharing\Sharee;
+use Sabre\Xml\XmlSerializable;
+use Sabre\Xml\Writer;
+
+/**
+ * This class represents the {DAV:}invite property.
+ *
+ * This property is defined here:
+ * https://tools.ietf.org/html/draft-pot-webdav-resource-sharing-03#section-4.4.2
+ *
+ * This property is used by clients to determine who currently has access to
+ * a shared resource, what their access level is and what their invite status
+ * is.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Invite implements XmlSerializable {
+
+    /**
+     * A list of sharees
+     *
+     * @var Sharee[]
+     */
+    public $sharees = [];
+
+    /**
+     * Creates the property.
+     *
+     * @param Sharee[] $sharees
+     */
+    function __construct(array $sharees) {
+
+        $this->sharees = $sharees;
+
+    }
+
+    /**
+     * The xmlSerialize method is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        foreach ($this->sharees as $sharee) {
+            $writer->writeElement('{DAV:}sharee', $sharee);
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/DAV/Xml/Property/LocalHref.php b/vendor/sabre/dav/lib/DAV/Xml/Property/LocalHref.php
new file mode 100644
index 000000000..76a27b95d
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAV/Xml/Property/LocalHref.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Sabre\DAV\Xml\Property;
+
+use Sabre\HTTP;
+
+/**
+ * LocalHref property
+ *
+ * Like the Href property, this element represents {DAV:}href. The difference
+ * is that this is used stricly for paths on the server. The LocalHref property
+ * will prepare the path so it's a valid URI.
+ *
+ * These two objects behave identically:
+ *    new LocalHref($path)
+ *    new Href(\Sabre\HTTP\encodePath($path))
+ *
+ * LocalPath basically ensures that your spaces are %20, and everything that
+ * needs to be is uri encoded.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class LocalHref extends Href {
+
+    /**
+     * Constructor
+     *
+     * You must either pass a string for a single href, or an array of hrefs.
+     *
+     * If auto-prefix is set to false, the hrefs will be treated as absolute
+     * and not relative to the servers base uri.
+     *
+     * @param string|string[] $href
+     */
+    function __construct($hrefs) {
+
+        parent::__construct(array_map(
+            function($href) {
+                return \Sabre\HTTP\encodePath($href);
+            },
+            (array)$hrefs
+        ));
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/DAV/Xml/Property/ShareAccess.php b/vendor/sabre/dav/lib/DAV/Xml/Property/ShareAccess.php
new file mode 100644
index 000000000..f27af5415
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAV/Xml/Property/ShareAccess.php
@@ -0,0 +1,143 @@
+<?php
+
+namespace Sabre\DAV\Xml\Property;
+
+use Sabre\DAV\Sharing\Plugin as SharingPlugin;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\Xml\Element;
+use Sabre\Xml\Reader;
+use Sabre\Xml\Writer;
+
+/**
+ * This class represents the {DAV:}share-access property.
+ *
+ * This property is defined here:
+ * https://tools.ietf.org/html/draft-pot-webdav-resource-sharing-03#section-4.4.1
+ *
+ * This property is used to indicate if a resource is a shared resource, and
+ * whether the instance of the shared resource is the original instance, or
+ * an instance belonging to a sharee.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ShareAccess implements Element {
+
+    /**
+     * Either SHARED or SHAREDOWNER
+     *
+     * @var int
+     */
+    protected $value;
+
+    /**
+     * Creates the property.
+     *
+     * The constructor value must be one of the
+     * \Sabre\DAV\Sharing\Plugin::ACCESS_ constants.
+     *
+     * @param int $shareAccess
+     */
+    function __construct($shareAccess) {
+
+        $this->value = $shareAccess;
+
+    }
+
+    /**
+     * Returns the current value.
+     *
+     * @return int
+     */
+    function getValue() {
+
+        return $this->value;
+
+    }
+
+    /**
+     * The xmlSerialize method is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        switch ($this->value) {
+
+            case SharingPlugin::ACCESS_NOTSHARED :
+                $writer->writeElement('{DAV:}not-shared');
+                break;
+            case SharingPlugin::ACCESS_SHAREDOWNER :
+                $writer->writeElement('{DAV:}shared-owner');
+                break;
+            case SharingPlugin::ACCESS_READ :
+                $writer->writeElement('{DAV:}read');
+                break;
+            case SharingPlugin::ACCESS_READWRITE :
+                $writer->writeElement('{DAV:}read-write');
+                break;
+            case SharingPlugin::ACCESS_NOACCESS :
+                $writer->writeElement('{DAV:}no-access');
+                break;
+
+        }
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = $reader->parseInnerTree();
+        foreach ($elems as $elem) {
+            switch ($elem['name']) {
+                case '{DAV:}not-shared' :
+                    return new self(SharingPlugin::ACCESS_NOTSHARED);
+                case '{DAV:}sharedowner' :
+                    return new self(SharingPlugin::ACCESS_SHAREDOWNER);
+                case '{DAV:}read' :
+                    return new self(SharingPlugin::ACCESS_READ);
+                case '{DAV:}read-write' :
+                    return new self(SharingPlugin::ACCESS_READWRITE);
+                case '{DAV:}no-access' :
+                    return new self(SharingPlugin::ACCESS_NOACCESS);
+            }
+        }
+        throw new BadRequest('Invalid value for {DAV:}share-access element');
+
+    }
+}
diff --git a/vendor/sabre/dav/lib/DAV/Xml/Request/ShareResource.php b/vendor/sabre/dav/lib/DAV/Xml/Request/ShareResource.php
new file mode 100644
index 000000000..965e5857c
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAV/Xml/Request/ShareResource.php
@@ -0,0 +1,81 @@
+<?php
+
+namespace Sabre\DAV\Xml\Request;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+use Sabre\DAV\Xml\Element\Sharee;
+
+/**
+ * ShareResource request parser.
+ *
+ * This class parses the {DAV:}share-resource POST request as defined in:
+ *
+ * https://tools.ietf.org/html/draft-pot-webdav-resource-sharing-01#section-5.3.2.1
+ *
+ * @copyright Copyright (C) 2007-2015 fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ShareResource implements XmlDeserializable {
+
+    /**
+     * The list of new people added or updated or removed from the share.
+     *
+     * @var Sharee[]
+     */
+    public $sharees = [];
+
+    /**
+     * Constructor
+     *
+     * @param Sharee[] $sharees
+     */
+    function __construct(array $sharees) {
+
+        $this->sharees = $sharees;
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = $reader->parseInnerTree([
+            '{DAV:}sharee'       => 'Sabre\DAV\Xml\Element\Sharee',
+            '{DAV:}share-access' => 'Sabre\DAV\Xml\Property\ShareAccess',
+            '{DAV:}prop'         => 'Sabre\Xml\Deserializer\keyValue',
+        ]);
+
+        $sharees = [];
+
+        foreach ($elems as $elem) {
+            if ($elem['name'] !== '{DAV:}sharee') continue;
+            $sharees[] = $elem['value'];
+
+        }
+
+        return new self($sharees);
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/DAVACL/ACLTrait.php b/vendor/sabre/dav/lib/DAVACL/ACLTrait.php
new file mode 100644
index 000000000..602654a2e
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAVACL/ACLTrait.php
@@ -0,0 +1,100 @@
+<?php
+
+namespace Sabre\DAVACL;
+
+/**
+ * This trait is a default implementation of the IACL interface.
+ *
+ * In many cases you only want to implement 1 or to of the IACL functions,
+ * this trait allows you to be a bit lazier.
+ *
+ * By default this trait grants all privileges to the owner of the resource.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (https://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+trait ACLTrait {
+
+    /**
+     * Returns the owner principal
+     *
+     * This must be a url to a principal, or null if there's no owner
+     *
+     * @return string|null
+     */
+    function getOwner() {
+
+        return null;
+
+    }
+
+    /**
+     * Returns a group principal
+     *
+     * This must be a url to a principal, or null if there's no owner
+     *
+     * @return string|null
+     */
+    function getGroup() {
+
+        return null;
+
+    }
+
+    /**
+     * Returns a list of ACE's for this node.
+     *
+     * Each ACE has the following properties:
+     *   * 'privilege', a string such as {DAV:}read or {DAV:}write. These are
+     *     currently the only supported privileges
+     *   * 'principal', a url to the principal who owns the node
+     *   * 'protected' (optional), indicating that this ACE is not allowed to
+     *      be updated.
+     *
+     * @return array
+     */
+    function getACL() {
+
+        return [
+            [
+                'privilege' => '{DAV:}all',
+                'principal' => '{DAV:}owner',
+                'protected' => true,
+            ]
+        ];
+
+    }
+
+    /**
+     * Updates the ACL
+     *
+     * This method will receive a list of new ACE's as an array argument.
+     *
+     * @param array $acl
+     * @return void
+     */
+    function setACL(array $acl) {
+
+        throw new \Sabre\DAV\Exception\Forbidden('Setting ACL is not supported on this node');
+    }
+
+    /**
+     * Returns the list of supported privileges for this node.
+     *
+     * The returned data structure is a list of nested privileges.
+     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
+     * standard structure.
+     *
+     * If null is returned from this method, the default privilege set is used,
+     * which is fine for most common usecases.
+     *
+     * @return array|null
+     */
+    function getSupportedPrivilegeSet() {
+
+        return null;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/DAVACL/AbstractPrincipalCollection.php b/vendor/sabre/dav/lib/DAVACL/AbstractPrincipalCollection.php
index 460f78981..9d2026380 100644
--- a/vendor/sabre/dav/lib/DAVACL/AbstractPrincipalCollection.php
+++ b/vendor/sabre/dav/lib/DAVACL/AbstractPrincipalCollection.php
@@ -110,7 +110,7 @@ abstract class AbstractPrincipalCollection extends DAV\Collection implements IPr
      *
      * @param string $name
      * @throws DAV\Exception\NotFound
-     * @return IPrincipal
+     * @return DAV\INode
      */
     function getChild($name) {
 
diff --git a/vendor/sabre/dav/lib/DAVACL/FS/Collection.php b/vendor/sabre/dav/lib/DAVACL/FS/Collection.php
index 5fab4768c..1c08b43b1 100644
--- a/vendor/sabre/dav/lib/DAVACL/FS/Collection.php
+++ b/vendor/sabre/dav/lib/DAVACL/FS/Collection.php
@@ -3,6 +3,7 @@
 namespace Sabre\DAVACL\FS;
 
 use Sabre\DAV\FSExt\Directory as BaseCollection;
+use Sabre\DAVACL\ACLTrait;
 use Sabre\DAVACL\IACL;
 use Sabre\DAV\Exception\Forbidden;
 use Sabre\DAV\Exception\NotFound;
@@ -16,6 +17,8 @@ use Sabre\DAV\Exception\NotFound;
  */
 class Collection extends BaseCollection implements IACL {
 
+    use ACLTrait;
+
     /**
      * A list of ACL rules.
      *
@@ -52,8 +55,8 @@ class Collection extends BaseCollection implements IACL {
      * exist.
      *
      * @param string $name
-     * @throws DAV\Exception\NotFound
-     * @return DAV\INode
+     * @throws NotFound
+     * @return \Sabre\DAV\INode
      */
     function getChild($name) {
 
@@ -88,19 +91,6 @@ class Collection extends BaseCollection implements IACL {
     }
 
     /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -118,36 +108,4 @@ class Collection extends BaseCollection implements IACL {
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's as an array argument.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new Forbidden('Setting ACL is not allowed here');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/DAVACL/FS/File.php b/vendor/sabre/dav/lib/DAVACL/FS/File.php
index 0d549528b..387597bf7 100644
--- a/vendor/sabre/dav/lib/DAVACL/FS/File.php
+++ b/vendor/sabre/dav/lib/DAVACL/FS/File.php
@@ -4,7 +4,7 @@ namespace Sabre\DAVACL\FS;
 
 use Sabre\DAV\FSExt\File as BaseFile;
 use Sabre\DAVACL\IACL;
-use Sabre\DAV\Exception\Forbidden;
+use Sabre\DAVACL\ACLTrait;
 
 /**
  * This is an ACL-enabled file node.
@@ -15,6 +15,8 @@ use Sabre\DAV\Exception\Forbidden;
  */
 class File extends BaseFile implements IACL {
 
+    use ACLTrait;
+
     /**
      * A list of ACL rules.
      *
@@ -58,19 +60,6 @@ class File extends BaseFile implements IACL {
     }
 
     /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -88,36 +77,4 @@ class File extends BaseFile implements IACL {
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's as an array argument.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new Forbidden('Setting ACL is not allowed here');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/DAVACL/FS/HomeCollection.php b/vendor/sabre/dav/lib/DAVACL/FS/HomeCollection.php
index c27616770..9e21353ea 100644
--- a/vendor/sabre/dav/lib/DAVACL/FS/HomeCollection.php
+++ b/vendor/sabre/dav/lib/DAVACL/FS/HomeCollection.php
@@ -2,8 +2,8 @@
 
 namespace Sabre\DAVACL\FS;
 
-use Sabre\DAV\Exception\Forbidden;
 use Sabre\DAVACL\AbstractPrincipalCollection;
+use Sabre\DAVACL\ACLTrait;
 use Sabre\DAVACL\IACL;
 use Sabre\DAVACL\PrincipalBackend\BackendInterface;
 use Sabre\Uri;
@@ -21,6 +21,8 @@ use Sabre\Uri;
  */
 class HomeCollection extends AbstractPrincipalCollection implements IACL {
 
+    use ACLTrait;
+
     /**
      * Name of this collection.
      *
@@ -70,20 +72,15 @@ class HomeCollection extends AbstractPrincipalCollection implements IACL {
      * supplied by the authentication backend.
      *
      * @param array $principalInfo
-     * @return void
+     * @return \Sabre\DAVACL\INode
      */
     function getChildForPrincipal(array $principalInfo) {
 
         $owner = $principalInfo['uri'];
         $acl = [
             [
-                'privilege' => '{DAV:}read',
-                'principal' => $owner,
-                'protected' => true,
-            ],
-            [
-                'privilege' => '{DAV:}write',
-                'principal' => $owner,
+                'privilege' => '{DAV:}all',
+                'principal' => '{DAV:}owner',
                 'protected' => true,
             ],
         ];
@@ -103,31 +100,6 @@ class HomeCollection extends AbstractPrincipalCollection implements IACL {
 
     }
 
-    /**
-     * Returns the owner principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getOwner() {
-
-        return null;
-
-    }
-
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
 
     /**
      * Returns a list of ACE's for this node.
@@ -153,36 +125,4 @@ class HomeCollection extends AbstractPrincipalCollection implements IACL {
 
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's as an array argument.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new Forbidden('Setting ACL is not allowed here');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/DAVACL/IACL.php b/vendor/sabre/dav/lib/DAVACL/IACL.php
index 81908d08f..f7a138665 100644
--- a/vendor/sabre/dav/lib/DAVACL/IACL.php
+++ b/vendor/sabre/dav/lib/DAVACL/IACL.php
@@ -71,5 +71,4 @@ interface IACL extends DAV\INode {
      */
     function getSupportedPrivilegeSet();
 
-
 }
diff --git a/vendor/sabre/dav/lib/DAVACL/Plugin.php b/vendor/sabre/dav/lib/DAVACL/Plugin.php
index 601dffecc..59a7b0922 100644
--- a/vendor/sabre/dav/lib/DAVACL/Plugin.php
+++ b/vendor/sabre/dav/lib/DAVACL/Plugin.php
@@ -4,7 +4,11 @@ namespace Sabre\DAVACL;
 
 use Sabre\DAV;
 use Sabre\DAV\INode;
+use Sabre\DAV\Xml\Property\Href;
 use Sabre\DAV\Exception\BadRequest;
+use Sabre\DAV\Exception\NotFound;
+use Sabre\DAV\Exception\NotAuthenticated;
+use Sabre\DAVACL\Exception\NeedPrivileges;
 use Sabre\HTTP\RequestInterface;
 use Sabre\HTTP\ResponseInterface;
 use Sabre\Uri;
@@ -64,18 +68,6 @@ class Plugin extends DAV\ServerPlugin {
     ];
 
     /**
-     * By default ACL is only enforced for nodes that have ACL support (the
-     * ones that implement IACL). For any other node, access is
-     * always granted.
-     *
-     * To override this behaviour you can turn this setting off. This is useful
-     * if you plan to fully support ACL in the entire tree.
-     *
-     * @var bool
-     */
-    public $allowAccessToNodesWithoutACL = true;
-
-    /**
      * By default nodes that are inaccessible by the user, can still be seen
      * in directory listings (PROPFIND on parent with Depth: 1)
      *
@@ -109,6 +101,18 @@ class Plugin extends DAV\ServerPlugin {
     public $adminPrincipals = [];
 
     /**
+     * The ACL plugin allows privileges to be assigned to users that are not
+     * logged in. To facilitate that, it modifies the auth plugin's behavior
+     * to only require login when a privileged operation was denied.
+     *
+     * Unauthenticated access can be considered a security concern, so it's
+     * possible to turn this feature off to harden the server's security.
+     *
+     * @var bool
+     */
+    public $allowUnauthenticatedAccess = true;
+
+    /**
      * Returns a list of features added by this plugin.
      *
      * This list is used in the response of a HTTP OPTIONS request.
@@ -161,6 +165,7 @@ class Plugin extends DAV\ServerPlugin {
 
         return [
             '{DAV:}expand-property',
+            '{DAV:}principal-match',
             '{DAV:}principal-property-search',
             '{DAV:}principal-search-property-set',
         ];
@@ -179,7 +184,8 @@ class Plugin extends DAV\ServerPlugin {
      * @param array|string $privileges
      * @param int $recursion
      * @param bool $throwExceptions if set to false, this method won't throw exceptions.
-     * @throws Sabre\DAVACL\Exception\NeedPrivileges
+     * @throws NeedPrivileges
+     * @throws NotAuthenticated
      * @return bool
      */
     function checkPrivileges($uri, $privileges, $recursion = self::R_PARENT, $throwExceptions = true) {
@@ -188,18 +194,6 @@ class Plugin extends DAV\ServerPlugin {
 
         $acl = $this->getCurrentUserPrivilegeSet($uri);
 
-        if (is_null($acl)) {
-            if ($this->allowAccessToNodesWithoutACL) {
-                return true;
-            } else {
-                if ($throwExceptions)
-                    throw new Exception\NeedPrivileges($uri, $privileges);
-                else
-                    return false;
-
-            }
-        }
-
         $failed = [];
         foreach ($privileges as $priv) {
 
@@ -210,10 +204,22 @@ class Plugin extends DAV\ServerPlugin {
         }
 
         if ($failed) {
-            if ($throwExceptions)
-                throw new Exception\NeedPrivileges($uri, $failed);
-            else
+            if ($this->allowUnauthenticatedAccess && is_null($this->getCurrentUserPrincipal())) {
+                // We are not authenticated. Kicking in the Auth plugin.
+                $authPlugin = $this->server->getPlugin('auth');
+                $reasons = $authPlugin->getLoginFailedReasons();
+                $authPlugin->challenge(
+                    $this->server->httpRequest,
+                    $this->server->httpResponse
+                );
+                throw new notAuthenticated(implode(', ', $reasons) . '. Login was needed for privilege: ' . implode(', ', $failed) . ' on ' . $uri);
+            }
+            if ($throwExceptions) {
+
+                throw new NeedPrivileges($uri, $failed);
+            } else {
                 return false;
+            }
         }
         return true;
 
@@ -229,10 +235,11 @@ class Plugin extends DAV\ServerPlugin {
      */
     function getCurrentUserPrincipal() {
 
-        $authPlugin = $this->server->getPlugin('auth');
-        if (is_null($authPlugin)) return null;
         /** @var $authPlugin Sabre\DAV\Auth\Plugin */
-
+        $authPlugin = $this->server->getPlugin('auth');
+        if (!$authPlugin) {
+            return null;
+        }
         return $authPlugin->getCurrentPrincipal();
 
     }
@@ -258,6 +265,56 @@ class Plugin extends DAV\ServerPlugin {
     }
 
     /**
+     * Sets the default ACL rules.
+     *
+     * These rules are used for all nodes that don't implement the IACL interface.
+     *
+     * @param array $acl
+     * @return void
+     */
+    function setDefaultAcl(array $acl) {
+
+        $this->defaultAcl = $acl;
+
+    }
+
+    /**
+     * Returns the default ACL rules.
+     *
+     * These rules are used for all nodes that don't implement the IACL interface.
+     *
+     * @param array $acl
+     * @return void
+     */
+    function getDefaultAcl() {
+
+        return $this->defaultAcl;
+
+    }
+
+    /**
+     * The default ACL rules.
+     *
+     * These rules are used for nodes that don't implement IACL. These default
+     * set of rules allow anyone to do anything, as long as they are
+     * authenticated.
+     *
+     * var array
+     */
+    protected $defaultAcl = [
+        [
+            'principal' => '{DAV:}authenticated',
+            'protected' => true,
+            'privilege' => '{DAV:}all',
+        ],
+        [
+            'principal' => '{DAV:}unauthenticated',
+            'protected' => true,
+            'privilege' => '{DAV:}read',
+        ],
+    ];
+
+    /**
      * This array holds a cache for all the principals that are associated with
      * a single principal.
      *
@@ -311,13 +368,77 @@ class Plugin extends DAV\ServerPlugin {
     }
 
     /**
-     * Returns the supported privilege structure for this ACL plugin.
+     * Find out of a principal equals another principal.
+     *
+     * This is a quick way to find out wether a principal URI is part of a
+     * group, or any subgroups.
      *
-     * See RFC3744 for more details. Currently we default on a simple,
-     * standard structure.
+     * The first argument is the principal URI you want to check against. For
+     * example the principal group, and the second argument is the principal of
+     * which you want to find out of it is the same as the first principal, or
+     * in a member of the first principal's group or subgroups.
      *
-     * You can either get the list of privileges by a uri (path) or by
-     * specifying a Node.
+     * So the arguments are not interchangable. If principal A is in group B,
+     * passing 'B', 'A' will yield true, but 'A', 'B' is false.
+     *
+     * If the sceond argument is not passed, we will use the current user
+     * principal.
+     *
+     * @param string $checkPrincipal
+     * @param string $currentPrincipal
+     * @return bool
+     */
+    function principalMatchesPrincipal($checkPrincipal, $currentPrincipal = null) {
+
+        if (is_null($currentPrincipal)) {
+            $currentPrincipal = $this->getCurrentUserPrincipal();
+        }
+        if ($currentPrincipal === $checkPrincipal) {
+            return true;
+        }
+        return in_array(
+            $checkPrincipal,
+            $this->getPrincipalMembership($currentPrincipal)
+        );
+
+    }
+
+
+    /**
+     * Returns a tree of supported privileges for a resource.
+     *
+     * The returned array structure should be in this form:
+     *
+     * [
+     *    [
+     *       'privilege' => '{DAV:}read',
+     *       'abstract'  => false,
+     *       'aggregates' => []
+     *    ]
+     * ]
+     *
+     * Privileges can be nested using "aggregrates". Doing so means that
+     * if you assign someone the aggregrating privilege, all the
+     * sub-privileges will automatically be granted.
+     *
+     * Marking a privilege as abstract means that the privilege cannot be
+     * directly assigned, but must be assigned via the parent privilege.
+     *
+     * So a more complex version might look like this:
+     *
+     * [
+     *    [
+     *       'privilege' => '{DAV:}read',
+     *       'abstract'  => false,
+     *       'aggregates' => [
+     *          [
+     *              'privilege'  => '{DAV:}read-acl',
+     *              'abstract'   => false,
+     *              'aggregates' => [],
+     *          ]
+     *       ]
+     *    ]
+     * ]
      *
      * @param string|INode $node
      * @return array
@@ -328,73 +449,71 @@ class Plugin extends DAV\ServerPlugin {
             $node = $this->server->tree->getNodeForPath($node);
         }
 
+        $supportedPrivileges = null;
         if ($node instanceof IACL) {
-            $result = $node->getSupportedPrivilegeSet();
-
-            if ($result)
-                return $result;
+            $supportedPrivileges = $node->getSupportedPrivilegeSet();
         }
 
-        return self::getDefaultSupportedPrivilegeSet();
+        if (is_null($supportedPrivileges)) {
 
-    }
-
-    /**
-     * Returns a fairly standard set of privileges, which may be useful for
-     * other systems to use as a basis.
-     *
-     * @return array
-     */
-    static function getDefaultSupportedPrivilegeSet() {
-
-        return [
-            'privilege'  => '{DAV:}all',
-            'abstract'   => true,
-            'aggregates' => [
-                [
-                    'privilege'  => '{DAV:}read',
+            // Default
+            $supportedPrivileges = [
+                '{DAV:}read' => [
+                    'abstract'   => false,
                     'aggregates' => [
-                        [
-                            'privilege' => '{DAV:}read-acl',
-                            'abstract'  => false,
+                        '{DAV:}read-acl' => [
+                            'abstract'   => false,
+                            'aggregates' => [],
                         ],
-                        [
-                            'privilege' => '{DAV:}read-current-user-privilege-set',
-                            'abstract'  => false,
+                        '{DAV:}read-current-user-privilege-set' => [
+                            'abstract'   => false,
+                            'aggregates' => [],
                         ],
                     ],
-                ], // {DAV:}read
-                [
-                    'privilege'  => '{DAV:}write',
+                ],
+                '{DAV:}write' => [
+                    'abstract'   => false,
                     'aggregates' => [
-                        [
-                            'privilege' => '{DAV:}write-acl',
-                            'abstract'  => false,
-                        ],
-                        [
-                            'privilege' => '{DAV:}write-properties',
-                            'abstract'  => false,
-                        ],
-                        [
-                            'privilege' => '{DAV:}write-content',
-                            'abstract'  => false,
+                        '{DAV:}write-properties' => [
+                            'abstract'   => false,
+                            'aggregates' => [],
                         ],
-                        [
-                            'privilege' => '{DAV:}bind',
-                            'abstract'  => false,
+                        '{DAV:}write-content' => [
+                            'abstract'   => false,
+                            'aggregates' => [],
                         ],
-                        [
-                            'privilege' => '{DAV:}unbind',
-                            'abstract'  => false,
-                        ],
-                        [
-                            'privilege' => '{DAV:}unlock',
-                            'abstract'  => false,
+                        '{DAV:}unlock' => [
+                            'abstract'   => false,
+                            'aggregates' => [],
                         ],
                     ],
-                ], // {DAV:}write
-            ],
-        ]; // {DAV:}all
+                ],
+            ];
+            if ($node instanceof \Sabre\DAV\ICollection) {
+                $supportedPrivileges['{DAV:}write']['aggregates']['{DAV:}bind'] = [
+                    'abstract'   => false,
+                    'aggregates' => [],
+                ];
+                $supportedPrivileges['{DAV:}write']['aggregates']['{DAV:}unbind'] = [
+                    'abstract'   => false,
+                    'aggregates' => [],
+                ];
+            }
+            if ($node instanceof \Sabre\DAVACL\IACL) {
+                $supportedPrivileges['{DAV:}write']['aggregates']['{DAV:}write-acl'] = [
+                    'abstract'   => false,
+                    'aggregates' => [],
+                ];
+            }
+
+        }
+
+        $this->server->emit(
+            'getSupportedPrivilegeSet',
+            [$node, &$supportedPrivileges]
+        );
+
+        return $supportedPrivileges;
 
     }
 
@@ -414,35 +533,38 @@ class Plugin extends DAV\ServerPlugin {
      */
     final function getFlatPrivilegeSet($node) {
 
-        $privs = $this->getSupportedPrivilegeSet($node);
+        $privs = [
+            'abstract'   => false,
+            'aggregates' => $this->getSupportedPrivilegeSet($node)
+        ];
 
         $fpsTraverse = null;
-        $fpsTraverse = function($priv, $concrete, &$flat) use (&$fpsTraverse) {
+        $fpsTraverse = function($privName, $privInfo, $concrete, &$flat) use (&$fpsTraverse) {
 
             $myPriv = [
-                'privilege'  => $priv['privilege'],
-                'abstract'   => isset($priv['abstract']) && $priv['abstract'],
+                'privilege'  => $privName,
+                'abstract'   => isset($privInfo['abstract']) && $privInfo['abstract'],
                 'aggregates' => [],
-                'concrete'   => isset($priv['abstract']) && $priv['abstract'] ? $concrete : $priv['privilege'],
+                'concrete'   => isset($privInfo['abstract']) && $privInfo['abstract'] ? $concrete : $privName,
             ];
 
-            if (isset($priv['aggregates'])) {
+            if (isset($privInfo['aggregates'])) {
 
-                foreach ($priv['aggregates'] as $subPriv) {
+                foreach ($privInfo['aggregates'] as $subPrivName => $subPrivInfo) {
 
-                    $myPriv['aggregates'][] = $subPriv['privilege'];
+                    $myPriv['aggregates'][] = $subPrivName;
 
                 }
 
             }
 
-            $flat[$priv['privilege']] = $myPriv;
+            $flat[$privName] = $myPriv;
 
-            if (isset($priv['aggregates'])) {
+            if (isset($privInfo['aggregates'])) {
 
-                foreach ($priv['aggregates'] as $subPriv) {
+                foreach ($privInfo['aggregates'] as $subPrivName => $subPrivInfo) {
 
-                    $fpsTraverse($subPriv, $myPriv['concrete'], $flat);
+                    $fpsTraverse($subPrivName, $subPrivInfo, $myPriv['concrete'], $flat);
 
                 }
 
@@ -451,7 +573,7 @@ class Plugin extends DAV\ServerPlugin {
         };
 
         $flat = [];
-        $fpsTraverse($privs, null, $flat);
+        $fpsTraverse('{DAV:}all', $privs, null, $flat);
 
         return $flat;
 
@@ -467,13 +589,13 @@ class Plugin extends DAV\ServerPlugin {
      * @param string|DAV\INode $node
      * @return array
      */
-    function getACL($node) {
+    function getAcl($node) {
 
         if (is_string($node)) {
             $node = $this->server->tree->getNodeForPath($node);
         }
         if (!$node instanceof IACL) {
-            return null;
+            return $this->getDefaultAcl();
         }
         $acl = $node->getACL();
         foreach ($this->adminPrincipals as $adminPrincipal) {
@@ -506,12 +628,10 @@ class Plugin extends DAV\ServerPlugin {
 
         $acl = $this->getACL($node);
 
-        if (is_null($acl)) return null;
-
-        $principals = $this->getCurrentUserPrincipals();
-
         $collected = [];
 
+        $isAuthenticated = $this->getCurrentUserPrincipal() !== null;
+
         foreach ($acl as $ace) {
 
             $principal = $ace['principal'];
@@ -520,7 +640,7 @@ class Plugin extends DAV\ServerPlugin {
 
                 case '{DAV:}owner' :
                     $owner = $node->getOwner();
-                    if ($owner && in_array($owner, $principals)) {
+                    if ($owner && $this->principalMatchesPrincipal($owner)) {
                         $collected[] = $ace;
                     }
                     break;
@@ -528,21 +648,25 @@ class Plugin extends DAV\ServerPlugin {
 
                 // 'all' matches for every user
                 case '{DAV:}all' :
+                    $collected[] = $ace;
+                    break;
 
-                // 'authenticated' matched for every user that's logged in.
-                // Since it's not possible to use ACL while not being logged
-                // in, this is also always true.
                 case '{DAV:}authenticated' :
-                    $collected[] = $ace;
+                    // Authenticated users only
+                    if ($isAuthenticated) {
+                        $collected[] = $ace;
+                    }
                     break;
 
-                // 'unauthenticated' can never occur either, so we simply
-                // ignore these.
                 case '{DAV:}unauthenticated' :
+                    // Unauthenticated users only
+                    if (!$isAuthenticated) {
+                        $collected[] = $ace;
+                    }
                     break;
 
                 default :
-                    if (in_array($ace['principal'], $principals)) {
+                    if ($this->principalMatchesPrincipal($ace['principal'])) {
                         $collected[] = $ace;
                     }
                     break;
@@ -561,6 +685,11 @@ class Plugin extends DAV\ServerPlugin {
             $current = array_pop($collected);
             $collected2[] = $current['privilege'];
 
+            if (!isset($flat[$current['privilege']])) {
+                // Ignoring privileges that are not in the supported-privileges list.
+                $this->server->getLogger()->debug('A node has the "' . $current['privilege'] . '" in its ACL list, but this privilege was not reported in the supportedPrivilegeSet list. This will be ignored.');
+                continue;
+            }
             foreach ($flat[$current['privilege']]['aggregates'] as $subPriv) {
                 $collected2[] = $subPriv;
                 $collected[] = $flat[$subPriv];
@@ -587,7 +716,13 @@ class Plugin extends DAV\ServerPlugin {
         $collections = $this->principalCollectionSet;
         foreach ($collections as $collection) {
 
-            $principalCollection = $this->server->tree->getNodeForPath($collection);
+            try {
+                $principalCollection = $this->server->tree->getNodeForPath($collection);
+            } catch (NotFound $e) {
+                // Ignore and move on
+                continue;
+            }
+
             if (!$principalCollection instanceof IPrincipalCollection) {
                 // Not a principal collection, we're simply going to ignore
                 // this.
@@ -673,6 +808,14 @@ class Plugin extends DAV\ServerPlugin {
      */
     function initialize(DAV\Server $server) {
 
+        if ($this->allowUnauthenticatedAccess) {
+            $authPlugin = $server->getPlugin('auth');
+            if (!$authPlugin) {
+                throw new \Exception('The Auth plugin must be loaded before the ACL plugin if you want to allow unauthenticated access.');
+            }
+            $authPlugin->autoRequireLogin = false;
+        }
+
         $this->server = $server;
         $server->on('propFind',            [$this, 'propFind'], 20);
         $server->on('beforeMethod',        [$this, 'beforeMethod'], 20);
@@ -683,6 +826,14 @@ class Plugin extends DAV\ServerPlugin {
         $server->on('report',              [$this, 'report']);
         $server->on('method:ACL',          [$this, 'httpAcl']);
         $server->on('onHTMLActionsPanel',  [$this, 'htmlActionsPanel']);
+        $server->on('getPrincipalByUri',  function($principal, &$uri) {
+
+            $uri = $this->getPrincipalByUri($principal);
+
+            // Break event chain
+            if ($uri) return false;
+
+        });
 
         array_push($server->protectedProperties,
             '{DAV:}alternate-URI-set',
@@ -707,9 +858,11 @@ class Plugin extends DAV\ServerPlugin {
         // class.
         $server->xml->elementMap['{DAV:}group-member-set'] = 'Sabre\\DAV\\Xml\\Property\\Href';
         $server->xml->elementMap['{DAV:}acl'] = 'Sabre\\DAVACL\\Xml\\Property\\Acl';
+        $server->xml->elementMap['{DAV:}acl-principal-prop-set'] = 'Sabre\\DAVACL\\Xml\\Request\\AclPrincipalPropSetReport';
         $server->xml->elementMap['{DAV:}expand-property'] = 'Sabre\\DAVACL\\Xml\\Request\\ExpandPropertyReport';
         $server->xml->elementMap['{DAV:}principal-property-search'] = 'Sabre\\DAVACL\\Xml\\Request\\PrincipalPropertySearchReport';
         $server->xml->elementMap['{DAV:}principal-search-property-set'] = 'Sabre\\DAVACL\\Xml\\Request\\PrincipalSearchPropertySetReport';
+        $server->xml->elementMap['{DAV:}principal-match'] = 'Sabre\\DAVACL\\Xml\\Request\\PrincipalMatchReport';
 
     }
 
@@ -743,7 +896,6 @@ class Plugin extends DAV\ServerPlugin {
 
             case 'PUT' :
             case 'LOCK' :
-            case 'UNLOCK' :
                 // This method requires the write-content priv if the node
                 // already exists, and bind on the parent if the node is being
                 // created.
@@ -751,6 +903,9 @@ class Plugin extends DAV\ServerPlugin {
                 $this->checkPrivileges($path, '{DAV:}write-content');
                 break;
 
+            case 'UNLOCK' :
+                // Unlock is always allowed at the moment.
+                break;
 
             case 'PROPPATCH' :
                 $this->checkPrivileges($path, '{DAV:}write-properties');
@@ -774,7 +929,6 @@ class Plugin extends DAV\ServerPlugin {
                 // If MOVE is used beforeUnbind will also be used to check if
                 // the sourcenode can be deleted.
                 $this->checkPrivileges($path, '{DAV:}read', self::R_RECURSIVE);
-
                 break;
 
         }
@@ -864,24 +1018,24 @@ class Plugin extends DAV\ServerPlugin {
         if ($node instanceof IPrincipal) {
 
             $propFind->handle('{DAV:}alternate-URI-set', function() use ($node) {
-                return new DAV\Xml\Property\Href($node->getAlternateUriSet());
+                return new Href($node->getAlternateUriSet());
             });
             $propFind->handle('{DAV:}principal-URL', function() use ($node) {
-                return new DAV\Xml\Property\Href($node->getPrincipalUrl() . '/');
+                return new Href($node->getPrincipalUrl() . '/');
             });
             $propFind->handle('{DAV:}group-member-set', function() use ($node) {
                 $members = $node->getGroupMemberSet();
                 foreach ($members as $k => $member) {
                     $members[$k] = rtrim($member, '/') . '/';
                 }
-                return new DAV\Xml\Property\Href($members);
+                return new Href($members);
             });
             $propFind->handle('{DAV:}group-membership', function() use ($node) {
                 $members = $node->getGroupMembership();
                 foreach ($members as $k => $member) {
                     $members[$k] = rtrim($member, '/') . '/';
                 }
-                return new DAV\Xml\Property\Href($members);
+                return new Href($members);
             });
             $propFind->handle('{DAV:}displayname', [$node, 'getDisplayName']);
 
@@ -892,7 +1046,7 @@ class Plugin extends DAV\ServerPlugin {
             $val = $this->principalCollectionSet;
             // Ensuring all collections end with a slash
             foreach ($val as $k => $v) $val[$k] = $v . '/';
-            return new DAV\Xml\Property\Href($val);
+            return new Href($val);
 
         });
         $propFind->handle('{DAV:}current-user-principal', function() {
@@ -910,9 +1064,7 @@ class Plugin extends DAV\ServerPlugin {
                 $propFind->set('{DAV:}current-user-privilege-set', null, 403);
             } else {
                 $val = $this->getCurrentUserPrivilegeSet($node);
-                if (!is_null($val)) {
-                    return new Xml\Property\CurrentUserPrivilegeSet($val);
-                }
+                return new Xml\Property\CurrentUserPrivilegeSet($val);
             }
         });
         $propFind->handle('{DAV:}acl', function() use ($node, $propFind, $path) {
@@ -921,9 +1073,7 @@ class Plugin extends DAV\ServerPlugin {
                 $propFind->set('{DAV:}acl', null, 403);
             } else {
                 $acl = $this->getACL($node);
-                if (!is_null($acl)) {
-                    return new Xml\Property\Acl($this->getACL($node));
-                }
+                return new Xml\Property\Acl($this->getACL($node));
             }
         });
         $propFind->handle('{DAV:}acl-restrictions', function() {
@@ -933,7 +1083,7 @@ class Plugin extends DAV\ServerPlugin {
         /* Adding ACL properties */
         if ($node instanceof IACL) {
             $propFind->handle('{DAV:}owner', function() use ($node) {
-                return new DAV\Xml\Property\Href($node->getOwner() . '/');
+                return new Href($node->getOwner() . '/');
             });
         }
 
@@ -952,7 +1102,7 @@ class Plugin extends DAV\ServerPlugin {
         $propPatch->handle('{DAV:}group-member-set', function($value) use ($path) {
             if (is_null($value)) {
                 $memberSet = [];
-            } elseif ($value instanceof DAV\Xml\Property\Href) {
+            } elseif ($value instanceof Href) {
                 $memberSet = array_map(
                     [$this->server, 'calculateUri'],
                     $value->getHrefs()
@@ -990,15 +1140,23 @@ class Plugin extends DAV\ServerPlugin {
 
             case '{DAV:}principal-property-search' :
                 $this->server->transactionType = 'report-principal-property-search';
-                $this->principalPropertySearchReport($report);
+                $this->principalPropertySearchReport($path, $report);
                 return false;
             case '{DAV:}principal-search-property-set' :
                 $this->server->transactionType = 'report-principal-search-property-set';
-                $this->principalSearchPropertySetReport($report);
+                $this->principalSearchPropertySetReport($path, $report);
                 return false;
             case '{DAV:}expand-property' :
                 $this->server->transactionType = 'report-expand-property';
-                $this->expandPropertyReport($report);
+                $this->expandPropertyReport($path, $report);
+                return false;
+            case '{DAV:}principal-match' :
+                $this->server->transactionType = 'report-principal-match';
+                $this->principalMatchReport($path, $report);
+                return false;
+            case '{DAV:}acl-principal-prop-set' :
+                $this->server->transactionType = 'acl-principal-prop-set';
+                $this->aclPrincipalPropSetReport($path, $report);
                 return false;
 
         }
@@ -1073,7 +1231,7 @@ class Plugin extends DAV\ServerPlugin {
             // Looking up the principal
             try {
                 $principal = $this->server->tree->getNodeForPath($newAce['principal']);
-            } catch (DAV\Exception\NotFound $e) {
+            } catch (NotFound $e) {
                 throw new Exception\NotRecognizedPrincipal('The specified principal (' . $newAce['principal'] . ') does not exist');
             }
             if (!($principal instanceof IPrincipal)) {
@@ -1095,7 +1253,110 @@ class Plugin extends DAV\ServerPlugin {
     /* Reports {{{ */
 
     /**
-     * The expand-property report is defined in RFC3253 section 3-8.
+     * The principal-match report is defined in RFC3744, section 9.3.
+     *
+     * This report allows a client to figure out based on the current user,
+     * or a principal URL, the principal URL and principal URLs of groups that
+     * principal belongs to.
+     *
+     * @param string $path
+     * @param Xml\Request\PrincipalMatchReport $report
+     * @return void
+     */
+    protected function principalMatchReport($path, Xml\Request\PrincipalMatchReport $report) {
+
+        $depth = $this->server->getHTTPDepth(0);
+        if ($depth !== 0) {
+            throw new BadRequest('The principal-match report is only defined on Depth: 0');
+        }
+
+        $currentPrincipals = $this->getCurrentUserPrincipals();
+
+        $result = [];
+
+        if ($report->type === Xml\Request\PrincipalMatchReport::SELF) {
+
+            // Finding all principals under the request uri that match the
+            // current principal.
+            foreach ($currentPrincipals as $currentPrincipal) {
+
+                if ($currentPrincipal === $path || strpos($currentPrincipal, $path . '/') === 0) {
+                    $result[] = $currentPrincipal;
+                }
+
+            }
+
+        } else {
+
+            // We need to find all resources that have a property that matches
+            // one of the current principals.
+            $candidates = $this->server->getPropertiesForPath(
+                $path,
+                [$report->principalProperty],
+                1
+            );
+
+            foreach ($candidates as $candidate) {
+
+                if (!isset($candidate[200][$report->principalProperty])) {
+                    continue;
+                }
+
+                $hrefs = $candidate[200][$report->principalProperty];
+
+                if (!$hrefs instanceof Href) {
+                    continue;
+                }
+
+                foreach ($hrefs->getHrefs() as $href) {
+                    if (in_array(trim($href, '/'), $currentPrincipals)) {
+                        $result[] = $candidate['href'];
+                        continue 2;
+                    }
+                }
+            }
+
+        }
+
+        $responses = [];
+
+        foreach ($result as $item) {
+
+            $properties = [];
+
+            if ($report->properties) {
+
+                $foo = $this->server->getPropertiesForPath($item, $report->properties);
+                $foo = $foo[0];
+                $item = $foo['href'];
+                unset($foo['href']);
+                $properties = $foo;
+
+            }
+
+            $responses[] = new DAV\Xml\Element\Response(
+                $item,
+                $properties,
+                '200'
+            );
+
+        }
+
+        $this->server->httpResponse->setHeader('Content-Type', 'application/xml; charset=utf-8');
+        $this->server->httpResponse->setStatus(207);
+        $this->server->httpResponse->setBody(
+            $this->server->xml->write(
+                '{DAV:}multistatus',
+                $responses,
+                $this->server->getBaseUri()
+            )
+        );
+
+
+    }
+
+    /**
+     * The expand-property report is defined in RFC3253 section 3.8.
      *
      * This report is very similar to a standard PROPFIND. The difference is
      * that it has the additional ability to look at properties containing a
@@ -1105,15 +1366,15 @@ class Plugin extends DAV\ServerPlugin {
      * Other rfc's, such as ACL rely on this report, so it made sense to put
      * it in this plugin.
      *
+     * @param string $path
      * @param Xml\Request\ExpandPropertyReport $report
      * @return void
      */
-    protected function expandPropertyReport($report) {
+    protected function expandPropertyReport($path, $report) {
 
         $depth = $this->server->getHTTPDepth(0);
-        $requestUri = $this->server->getRequestUri();
 
-        $result = $this->expandProperties($requestUri, $report->properties, $depth);
+        $result = $this->expandProperties($path, $report->properties, $depth);
 
         $xml = $this->server->xml->write(
             '{DAV:}multistatus',
@@ -1187,10 +1448,11 @@ class Plugin extends DAV\ServerPlugin {
      * of properties the client may search on, using the
      * {DAV:}principal-property-search report.
      *
+     * @param string $path
      * @param Xml\Request\PrincipalSearchPropertySetReport $report
      * @return void
      */
-    protected function principalSearchPropertySetReport($report) {
+    protected function principalSearchPropertySetReport($path, $report) {
 
         $httpDepth = $this->server->getHTTPDepth(0);
         if ($httpDepth !== 0) {
@@ -1241,14 +1503,14 @@ class Plugin extends DAV\ServerPlugin {
      * clients to search for groups of principals, based on the value of one
      * or more properties.
      *
+     * @param string $path
      * @param Xml\Request\PrincipalPropertySearchReport $report
      * @return void
      */
-    protected function principalPropertySearchReport($report) {
+    protected function principalPropertySearchReport($path, Xml\Request\PrincipalPropertySearchReport $report) {
 
-        $uri = null;
-        if (!$report->applyToPrincipalCollectionSet) {
-            $uri = $this->server->httpRequest->getPath();
+        if ($report->applyToPrincipalCollectionSet) {
+            $path = null;
         }
         if ($this->server->getHttpDepth('0') !== 0) {
             throw new BadRequest('Depth must be 0');
@@ -1256,7 +1518,7 @@ class Plugin extends DAV\ServerPlugin {
         $result = $this->principalSearch(
             $report->searchProperties,
             $report->properties,
-            $uri,
+            $path,
             $report->test
         );
 
@@ -1269,6 +1531,64 @@ class Plugin extends DAV\ServerPlugin {
 
     }
 
+    /**
+     * aclPrincipalPropSet REPORT
+     *
+     * This method is responsible for handling the {DAV:}acl-principal-prop-set
+     * REPORT, as defined in:
+     *
+     * https://tools.ietf.org/html/rfc3744#section-9.2
+     *
+     * This REPORT allows a user to quickly fetch information about all
+     * principals specified in the access control list. Most commonly this
+     * is used to for example generate a UI with ACL rules, allowing you
+     * to show names for principals for every entry.
+     *
+     * @param string $path
+     * @param Xml\Request\AclPrincipalPropSetReport $report
+     * @return void
+     */
+    protected function aclPrincipalPropSetReport($path, Xml\Request\AclPrincipalPropSetReport $report) {
+
+        if ($this->server->getHTTPDepth(0) !== 0) {
+            throw new BadRequest('The {DAV:}acl-principal-prop-set REPORT only supports Depth 0');
+        }
+
+        // Fetching ACL rules for the given path. We're using the property
+        // API and not the local getACL, because it will ensure that all
+        // business rules and restrictions are applied.
+        $acl = $this->server->getProperties($path, '{DAV:}acl');
+
+        if (!$acl || !isset($acl['{DAV:}acl'])) {
+            throw new Forbidden('Could not fetch ACL rules for this path');
+        }
+
+        $principals = [];
+        foreach ($acl['{DAV:}acl']->getPrivileges() as $ace) {
+
+            if ($ace['principal'][0] === '{') {
+                // It's not a principal, it's one of the special rules such as {DAV:}authenticated
+                continue;
+            }
+
+            $principals[] = $ace['principal'];
+
+        }
+
+        $properties = $this->server->getPropertiesForMultiplePaths(
+            $principals,
+            $report->properties
+        );
+
+        $this->server->httpResponse->setStatus(207);
+        $this->server->httpResponse->setHeader('Content-Type', 'application/xml; charset=utf-8');
+        $this->server->httpResponse->setBody(
+            $this->server->generateMultiStatus($properties)
+        );
+
+    }
+
+
     /* }}} */
 
     /**
diff --git a/vendor/sabre/dav/lib/DAVACL/Principal.php b/vendor/sabre/dav/lib/DAVACL/Principal.php
index 16375d3fc..6ebb30907 100644
--- a/vendor/sabre/dav/lib/DAVACL/Principal.php
+++ b/vendor/sabre/dav/lib/DAVACL/Principal.php
@@ -22,6 +22,8 @@ use Sabre\HTTP\URLUtil;
  */
 class Principal extends DAV\Node implements IPrincipal, DAV\IProperties, IACL {
 
+    use ACLTrait;
+
     /**
      * Struct with principal information.
      *
@@ -216,73 +218,4 @@ class Principal extends DAV\Node implements IPrincipal, DAV\IProperties, IACL {
 
     }
 
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-
-        return null;
-
-    }
-
-    /**
-     * Returns a list of ACE's for this node.
-     *
-     * Each ACE has the following properties:
-     *   * 'privilege', a string such as {DAV:}read or {DAV:}write. These are
-     *     currently the only supported privileges
-     *   * 'principal', a url to the principal who owns the node
-     *   * 'protected' (optional), indicating that this ACE is not allowed to
-     *      be updated.
-     *
-     * @return array
-     */
-    function getACL() {
-
-        return [
-            [
-                'privilege' => '{DAV:}read',
-                'principal' => '{DAV:}authenticated',
-                'protected' => true,
-            ],
-        ];
-
-    }
-
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new DAV\Exception\MethodNotAllowed('Updating ACLs is not allowed here');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/DAVACL/PrincipalBackend/PDO.php b/vendor/sabre/dav/lib/DAVACL/PrincipalBackend/PDO.php
index 01b7a175c..a491dc88f 100644
--- a/vendor/sabre/dav/lib/DAVACL/PrincipalBackend/PDO.php
+++ b/vendor/sabre/dav/lib/DAVACL/PrincipalBackend/PDO.php
@@ -300,7 +300,7 @@ class PDO extends AbstractBackend implements CreatePrincipalSupport {
         $value = null;
         $scheme = null;
         list($scheme, $value) = explode(":", $uri, 2);
-        if ($value == null) return null;
+        if (empty($value)) return null;
 
         $uri = null;
         switch ($scheme){
diff --git a/vendor/sabre/dav/lib/DAVACL/PrincipalCollection.php b/vendor/sabre/dav/lib/DAVACL/PrincipalCollection.php
index 54911e7b5..d8a90153a 100644
--- a/vendor/sabre/dav/lib/DAVACL/PrincipalCollection.php
+++ b/vendor/sabre/dav/lib/DAVACL/PrincipalCollection.php
@@ -3,7 +3,6 @@
 namespace Sabre\DAVACL;
 
 use Sabre\DAV\Exception\InvalidResourceType;
-use Sabre\DAV\Exception\Forbidden;
 use Sabre\DAV\IExtendedCollection;
 use Sabre\DAV\MkCol;
 
@@ -19,6 +18,8 @@ use Sabre\DAV\MkCol;
  */
 class PrincipalCollection extends AbstractPrincipalCollection implements IExtendedCollection, IACL {
 
+    use ACLTrait;
+
     /**
      * This method returns a node for a principal.
      *
@@ -73,28 +74,6 @@ class PrincipalCollection extends AbstractPrincipalCollection implements IExtend
     }
 
     /**
-     * Returns the owner principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getOwner() {
-        return null;
-    }
-
-    /**
-     * Returns a group principal
-     *
-     * This must be a url to a principal, or null if there's no owner
-     *
-     * @return string|null
-     */
-    function getGroup() {
-        return null;
-    }
-
-    /**
      * Returns a list of ACE's for this node.
      *
      * Each ACE has the following properties:
@@ -116,36 +95,4 @@ class PrincipalCollection extends AbstractPrincipalCollection implements IExtend
         ];
     }
 
-    /**
-     * Updates the ACL
-     *
-     * This method will receive a list of new ACE's as an array argument.
-     *
-     * @param array $acl
-     * @return void
-     */
-    function setACL(array $acl) {
-
-        throw new Forbidden('Updating ACLs is not allowed on this node');
-
-    }
-
-    /**
-     * Returns the list of supported privileges for this node.
-     *
-     * The returned data structure is a list of nested privileges.
-     * See Sabre\DAVACL\Plugin::getDefaultSupportedPrivilegeSet for a simple
-     * standard structure.
-     *
-     * If null is returned from this method, the default privilege set is used,
-     * which is fine for most common usecases.
-     *
-     * @return array|null
-     */
-    function getSupportedPrivilegeSet() {
-
-        return null;
-
-    }
-
 }
diff --git a/vendor/sabre/dav/lib/DAVACL/Xml/Property/SupportedPrivilegeSet.php b/vendor/sabre/dav/lib/DAVACL/Xml/Property/SupportedPrivilegeSet.php
index 572bed4dd..55e7783ae 100644
--- a/vendor/sabre/dav/lib/DAVACL/Xml/Property/SupportedPrivilegeSet.php
+++ b/vendor/sabre/dav/lib/DAVACL/Xml/Property/SupportedPrivilegeSet.php
@@ -73,7 +73,7 @@ class SupportedPrivilegeSet implements XmlSerializable, HtmlOutput {
      */
     function xmlSerialize(Writer $writer) {
 
-        $this->serializePriv($writer, $this->privileges);
+        $this->serializePriv($writer, '{DAV:}all', [ 'aggregates' => $this->privileges]);
 
     }
 
@@ -93,9 +93,9 @@ class SupportedPrivilegeSet implements XmlSerializable, HtmlOutput {
      */
     function toHtml(HtmlOutputHelper $html) {
 
-        $traverse = function($priv) use (&$traverse, $html) {
+        $traverse = function($privName, $priv) use (&$traverse, $html) {
             echo "<li>";
-            echo $html->xmlName($priv['privilege']);
+            echo $html->xmlName($privName);
             if (isset($priv['abstract']) && $priv['abstract']) {
                 echo " <i>(abstract)</i>";
             }
@@ -104,8 +104,8 @@ class SupportedPrivilegeSet implements XmlSerializable, HtmlOutput {
             }
             if (isset($priv['aggregates'])) {
                 echo "\n<ul>\n";
-                foreach ($priv['aggregates'] as $subPriv) {
-                    $traverse($subPriv);
+                foreach ($priv['aggregates'] as $subPrivName => $subPriv) {
+                    $traverse($subPrivName, $subPriv);
                 }
                 echo "</ul>";
             }
@@ -114,7 +114,7 @@ class SupportedPrivilegeSet implements XmlSerializable, HtmlOutput {
 
         ob_start();
         echo "<ul class=\"tree\">";
-        $traverse($this->getValue());
+        $traverse('{DAV:}all', [ 'aggregates' => $this->getValue() ]);
         echo "</ul>\n";
 
         return ob_get_clean();
@@ -132,12 +132,12 @@ class SupportedPrivilegeSet implements XmlSerializable, HtmlOutput {
      * @param array $privilege
      * @return void
      */
-    private function serializePriv(Writer $writer, $privilege) {
+    private function serializePriv(Writer $writer, $privName, $privilege) {
 
         $writer->startElement('{DAV:}supported-privilege');
 
         $writer->startElement('{DAV:}privilege');
-        $writer->writeElement($privilege['privilege']);
+        $writer->writeElement($privName);
         $writer->endElement(); // privilege
 
         if (!empty($privilege['abstract'])) {
@@ -147,8 +147,8 @@ class SupportedPrivilegeSet implements XmlSerializable, HtmlOutput {
             $writer->writeElement('{DAV:}description', $privilege['description']);
         }
         if (isset($privilege['aggregates'])) {
-            foreach ($privilege['aggregates'] as $subPrivilege) {
-                $this->serializePriv($writer, $subPrivilege);
+            foreach ($privilege['aggregates'] as $subPrivName => $subPrivilege) {
+                $this->serializePriv($writer, $subPrivName, $subPrivilege);
             }
         }
 
diff --git a/vendor/sabre/dav/lib/DAVACL/Xml/Request/AclPrincipalPropSetReport.php b/vendor/sabre/dav/lib/DAVACL/Xml/Request/AclPrincipalPropSetReport.php
new file mode 100644
index 000000000..f01c1e6ab
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAVACL/Xml/Request/AclPrincipalPropSetReport.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace Sabre\DAVACL\Xml\Request;
+
+use Sabre\Xml\XmlDeserializable;
+use Sabre\Xml\Reader;
+use Sabre\Xml\Deserializer;
+
+/**
+ * AclPrincipalPropSet request parser.
+ *
+ * This class parses the {DAV:}acl-principal-prop-set REPORT, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc3744#section-9.2
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (https://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class AclPrincipalPropSetReport implements XmlDeserializable {
+
+    public $properties = [];
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+       
+        $reader->pushContext();
+        $reader->elementMap['{DAV:}prop'] = 'Sabre\Xml\Deserializer\enum';
+
+        $elems = Deserializer\keyValue(
+            $reader,
+            'DAV:'
+        );
+
+        $reader->popContext();
+
+        $report = new self();
+
+        if (!empty($elems['prop'])) {
+            $report->properties = $elems['prop'];
+        }
+
+        return $report;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/DAVACL/Xml/Request/PrincipalMatchReport.php b/vendor/sabre/dav/lib/DAVACL/Xml/Request/PrincipalMatchReport.php
new file mode 100644
index 000000000..5c4e88189
--- /dev/null
+++ b/vendor/sabre/dav/lib/DAVACL/Xml/Request/PrincipalMatchReport.php
@@ -0,0 +1,107 @@
+<?php
+
+namespace Sabre\DAVACL\Xml\Request;
+
+use Sabre\Xml\XmlDeserializable;
+use Sabre\Xml\Reader;
+use Sabre\Xml\Deserializer;
+
+/**
+ * PrincipalMatchReport request parser.
+ *
+ * This class parses the {DAV:}principal-match REPORT, as defined
+ * in:
+ *
+ * https://tools.ietf.org/html/rfc3744#section-9.3
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class PrincipalMatchReport implements XmlDeserializable {
+
+    /**
+     * Report on a list of principals that match the current principal.
+     */
+    const SELF = 1;
+
+    /**
+     * Report on a property on resources, such as {DAV:}owner, that match the current principal.
+     */
+    const PRINCIPAL_PROPERTY = 2;
+
+    /**
+     * Must be SELF or PRINCIPAL_PROPERTY
+     *
+     * @var int
+     */
+    public $type;
+
+    /**
+     * List of properties that are being requested for matching resources.
+     *
+     * @var string[]
+     */
+    public $properties = [];
+
+    /**
+     * If $type = PRINCIPAL_PROPERTY, which WebDAV property we should compare
+     * to the current principal.
+     *
+     * @var string
+     */
+    public $principalProperty;
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $reader->pushContext();
+        $reader->elementMap['{DAV:}prop'] = 'Sabre\Xml\Deserializer\enum';
+
+        $elems = Deserializer\keyValue(
+            $reader,
+            'DAV:'
+        );
+
+        $reader->popContext();
+
+        $principalMatch = new self();
+
+        if (array_key_exists('self', $elems)) {
+            $principalMatch->type = self::SELF;
+        }
+
+        if (array_key_exists('principal-property', $elems)) {
+            $principalMatch->type = self::PRINCIPAL_PROPERTY;
+            $principalMatch->principalProperty = $elems['principal-property'][0]['name'];
+        }
+
+        if (!empty($elems['prop'])) {
+            $principalMatch->properties = $elems['prop'];
+        }
+
+        return $principalMatch;
+
+    }
+
+}