From 19f3c454b374abdb25d1fd01512ee20626a950e5 Mon Sep 17 00:00:00 2001
From: Evert Pot <me@evertpot.com>
Date: Mon, 24 Oct 2016 01:06:21 -0400
Subject: [PATCH] Catching another infinite loop condition.

Fixes #329. Thanks for the research @PHPGangsta
---
 CHANGELOG.md                                  |  2 +
 lib/Recur/RRuleIterator.php                   | 20 ++++++++--
 .../EventIterator/InfiniteLoopProblemTest.php | 39 +++++++++++++++++++
 3 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0071f367..40a71bc44 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ ChangeLog
 ------------------
 
 * 
+* #329: Infinite loop when using `BYMONTHDAY`, `BYDAY` and/or `BYSETPOS` to
+  expand a `BYMONTH` rule.
 
 4.1.6 (2018-04-20)
 ------------------
diff --git a/lib/Recur/RRuleIterator.php b/lib/Recur/RRuleIterator.php
index dbea1155d..473413ca5 100644
--- a/lib/Recur/RRuleIterator.php
+++ b/lib/Recur/RRuleIterator.php
@@ -620,12 +620,14 @@ protected function nextYearly() {
 
         }
 
-        $currentMonth = $this->currentDate->format('n');
-        $currentYear = $this->currentDate->format('Y');
-        $currentDayOfMonth = $this->currentDate->format('j');
+        //$currentMonth = $this->currentDate->format('n');
+        //$currentYear = $this->currentDate->format('Y');
+        //$currentDayOfMonth = $this->currentDate->format('j');
 
         $advancedToNewMonth = false;
 
+        $noOccurrenceCounter = 0;
+
         // If we got a byDay or getMonthDay filter, we must first expand
         // further.
         if ($this->byDay || $this->byMonthDay) {
@@ -633,6 +635,18 @@ protected function nextYearly() {
             while (true) {
 
                 $occurrences = $this->getMonthlyOccurrences();
+                if(!$occurrences) {
+                    // We are counting subsequent months where there weren't
+                    // occurrences. If we exceed the treshold we might be
+                    // dealing with a recurrence rule that doesn't generate
+                    // valid instances.
+                    $noOccurrenceCounter++;
+                    if (++$noOccurrenceCounter > 10) {
+                        throw new InvalidDataException('BYDAY, BYMONTHDAY and/or BYSETPOS rules don\'t generate valid recurrence instances');
+                    }
+                } else {
+                    $noOccurrenceCounter = 0;
+                }
 
                 foreach ($occurrences as $occurrence) {
 
diff --git a/tests/VObject/Recur/EventIterator/InfiniteLoopProblemTest.php b/tests/VObject/Recur/EventIterator/InfiniteLoopProblemTest.php
index 0ba7296a5..dc00267cd 100644
--- a/tests/VObject/Recur/EventIterator/InfiniteLoopProblemTest.php
+++ b/tests/VObject/Recur/EventIterator/InfiniteLoopProblemTest.php
@@ -7,6 +7,7 @@
 use PHPUnit\Framework\TestCase;
 use Sabre\VObject\Component\VCalendar;
 use Sabre\VObject\Recur;
+use Sabre\VObject\Reader;
 
 class InfiniteLoopProblemTest extends TestCase {
 
@@ -96,4 +97,42 @@ function testZeroInterval() {
 
     }
 
+    /**
+     * Another infinite loop, from Issue #329.
+     *
+     * This was triggered due to a BYMONTHDAY rule that was using a value that
+     * never occurred in the BYMONTH rule.
+     *
+     * This bug surfaced similar issues with BYDAY and BYSETPOS.
+     *
+     * @expectedException \Sabre\VObject\InvalidDataException
+     */
+    function testBadByMonthday() {
+
+        $input = Reader::read(<<<ICS
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//something//DE
+CALSCALE:GREGORIAN
+X-WR-TIMEZONE:Europe/Berlin
+BEGIN:VEVENT
+UID:20160103T123422CET-9863LIMv8E
+DTSTAMP:20160103T113422Z
+DESCRIPTION:important date
+DTSTART;TZID=Europe/Berlin:20151231T000000
+DTEND;TZID=Europe/Berlin:20151231T235900
+RRULE:FREQ=YEARLY;COUNT=6;BYMONTHDAY=31;BYMONTH=11
+SUMMARY:important date
+TRANSP:OPAQUE
+END:VEVENT
+END:VCALENDAR
+ICS
+        );
+        $input->expand(
+            new DateTimeImmutable('2015-01-01'),
+            new DateTimeImmutable('2016-01-01')
+        );
+
+    }
+
 }