1 files changed, 31 insertions, 8 deletions

diff --git a/3rdparty/Sabre/CalDAV/CalendarQueryValidator.php b/3rdparty/Sabre/CalDAV/CalendarQueryValidator.php
index 1bb6b5d53fa..8f674840e87 100644..100755
--- a/3rdparty/Sabre/CalDAV/CalendarQueryValidator.php
+++ b/3rdparty/Sabre/CalDAV/CalendarQueryValidator.php
@@ -294,6 +294,7 @@ class Sabre_CalDAV_CalendarQueryValidator {
                 // in the VALARM component code, so this is a hack, and an
                 // expensive one too.
                 if ($component->parent->name === 'VEVENT' && $component->parent->RRULE) {
+
                     // Fire up the iterator!
                     $it = new Sabre_VObject_RecurrenceIterator($component->parent->parent, (string)$component->parent->UID);
                     while($it->valid()) {
@@ -303,15 +304,37 @@ class Sabre_CalDAV_CalendarQueryValidator {
                         // one is the first to trigger. Based on this, we can
                         // determine if we can 'give up' expanding events.
                         $firstAlarm = null;
-                        foreach($expandedEvent->VALARM as $expandedAlarm) {
-                            $effectiveTrigger = $expandedAlarm->getEffectiveTriggerTime();
-                            if (!$firstAlarm || $effectiveTrigger < $firstAlarm) {
-                                $firstAlarm = $effectiveTrigger;
-                            }
-                            if ($expandedAlarm->isInTimeRange($start, $end)) {
-                                return true;
+                        if ($expandedEvent->VALARM !== null) {
+                            foreach($expandedEvent->VALARM as $expandedAlarm) {
+
+                                $effectiveTrigger = $expandedAlarm->getEffectiveTriggerTime();
+                                if ($expandedAlarm->isInTimeRange($start, $end)) {
+                                    return true;
+                                }
+
+                                if ((string)$expandedAlarm->TRIGGER['VALUE'] === 'DATE-TIME') {
+                                    // This is an alarm with a non-relative trigger
+                                    // time, likely created by a buggy client. The
+                                    // implication is that every alarm in this
+                                    // recurring event trigger at the exact same
+                                    // time. It doesn't make sense to traverse
+                                    // further.
+                                } else {
+                                    // We store the first alarm as a means to
+                                    // figure out when we can stop traversing.
+                                    if (!$firstAlarm || $effectiveTrigger < $firstAlarm) {
+                                        $firstAlarm = $effectiveTrigger;
+                                    }
+                                }
                             }
-
+                        }
+                        if (is_null($firstAlarm)) {
+                            // No alarm was found.
+                            //
+                            // Or technically: No alarm that will change for
+                            // every instance of the recurrence was found,
+                            // which means we can assume there was no match.
+                            return false;
                         }
                         if ($firstAlarm > $end) {
                             return false;