ZP-1224 Pass PHP supported timezone to DateTimeZone.

Released under the Affero GNU General Public License (AGPL) version 3.

src/backend/caldav/caldav.php

@@ -538,7 +538,7 @@ class BackendCalDAV extends BackendDiff {
         $timezones = $ical->GetComponents("VTIMEZONE");
         $timezone = "";
         if (count($timezones) > 0) {
-            $timezone = TimezoneUtil::ParseTimezone($timezones[0]->GetPValue("TZID"));
+            $timezone = TimezoneUtil::GetPhpSupportedTimezone($timezones[0]->GetPValue("TZID"));
         }
         if (!$timezone) {
             $timezone = date_default_timezone_get();
@@ -1449,6 +1449,7 @@ class BackendCalDAV extends BackendDiff {
      * @throws Exception
      */
     private function _GetTimezoneString($timezone, $with_names = true) {
+        ZLog::Write(LOGLEVEL_DEBUG, sprintf("BackendCalDAV->_GetTimezoneString(): using '%s' timezone", $timezone));
         // UTC needs special handling
         if ($timezone == "UTC")
             return base64_encode(pack('la64vvvvvvvvla64vvvvvvvvl', 0, '', 0, 0, 0, 0, 0, 0, 0, 0, 0, '', 0, 0, 0, 0, 0, 0, 0, 0, 0));

src/lib/utils/timezoneutil.php

@@ -1359,4 +1359,23 @@ class TimezoneUtil {
         }
         return self::getMSTZnameFromTZName(trim($timezone, '"'));
     }
+
+    /**
+     * Returns a timezone supported by PHP for DateTimeZone constructor.
+     * @see http://php.net/manual/en/timezones.php
+     *
+     * @param string $timezone
+     *
+     * @access public
+     * @return string
+     */
+    public static function GetPhpSupportedTimezone($timezone) {
+        if (in_array($timezone, DateTimeZone::listIdentifiers())) {
+            ZLog::Write(LOGLEVEL_DEBUG, sprintf("TimezoneUtil::GetPhpSupportedTimezone(): '%s' is a PHP supported timezone", $timezone));
+            return $timezone;
+        }
+        $dtz = date_default_timezone_get();
+        ZLog::Write(LOGLEVEL_DEBUG, sprintf("TimezoneUtil::GetPhpSupportedTimezone(): '%s' is not a PHP supported timezone. Returning default timezone: '%s'", $timezone, $dtz));
+        return $dtz;
+    }
 }