Support start or end missing from free-busy-query REPORT

Previously if either start or end were missing then the current time was
used. This would almost never be the expected behaviour.

ChangeLog

@@ -1,3 +1,7 @@
+2024-03-02 Andrew Ruthve <andrew@etc.gen.nz>
+	* Fix free-busy-query REPORT if start/end is missing, previously the
+	  current timestamp was used for missing values.
+
 2023-03-02 Florian Schlichting <fsfs@debian.org>
 	* release davical 1.1.12
 	* add Debian autopkgtests

inc/caldav-REPORT-freebusy.php

@@ -10,9 +10,34 @@ $fbq_end   = $fbq_content[0]->GetAttribute('end');
 if ( ! ( isset($fbq_start) || isset($fbq_end) ) ) {
   $request->DoResponse( 400, 'All valid freebusy requests MUST contain a time-range filter' );
 }
-$range_start = new RepeatRuleDateTime($fbq_start);
-$range_end   = new RepeatRuleDateTime($fbq_end);
 
+if ( isset($fbq_start) ) {
+  $range_start = new RepeatRuleDateTime($fbq_start);
+} else {
+  # RFC 4791 Section 9.9 says that if start isn't set, then -infinity
+  # should be used. We can't specify that in PHP, and
+  # expand_event_instances has '-6 weeks' as the default.
+  # That's a bit short, go for one year prior to end, if defined,
+  # otherwise 1 year prior to now now.
+  if ( isset($fbq_end) ) {
+    $range_start = new RepeatRuleDateTime($fbq_end);
+  } else {
+    $range_start = new RepeatRuleDateTime;
+  }
+
+  $range_start->modify('-365 days');
+}
+
+if ( isset($fbq_end) ) {
+  $range_end = new RepeatRuleDateTime($fbq_end);
+} else {
+  # RFC 4791 Section 9.9 says that if end isn't set, then +infinity
+  # should be used. We can't specify that in PHP, and
+  # expand_event_instances has '+ 6 weeks' as the default. That's a
+  # bit short, go for two years from the start.
+  $range_end = clone($range_start);
+  $range_end->modify('+730 days');
+}
 
 /** We use the same code for the REPORT, the POST and the freebusy GET... */
 $freebusy = get_freebusy( '^' . $request->path . $request->DepthRegexTail(true), $range_start, $range_end );

testing/tests/regression-suite/2605-REPORT-freebusy-no-start-no-end.result

@@ -0,0 +1,8 @@
+HTTP/1.1 400 Bad Request
+Date: Dow, 01 Jan 2000 00:00:00 GMT
+DAV: 1, 2, 3, access-control, calendar-access, calendar-schedule
+DAV: extended-mkcol, bind, addressbook, calendar-auto-schedule, calendar-proxy
+Content-Length: 60
+Content-Type: text/plain; charset="utf-8"
+
+All valid freebusy requests MUST contain a time-range filter

testing/tests/regression-suite/2605-REPORT-freebusy-no-start-no-end.test

@@ -0,0 +1,20 @@
+#
+# Request a REPORT with no start end end set, should return an error.
+#
+TYPE=REPORT
+URL=http://regression.host/caldav.php/user1/291-test-fb-rr-changes/
+HEADER=Accept: text/calendar
+HEADER=Content-Type: text/xml
+HEADER=Depth: 1
+HEAD
+
+AUTH=user4:user4
+
+BEGINDATA
+<?xml version="1.0" encoding="utf-8" ?>
+<C:free-busy-query xmlns:C="urn:ietf:params:xml:ns:caldav">
+  <C:time-range />
+</C:free-busy-query>
+ENDDATA
+
+REPLACE=/^DTSTAMP:\d{8}T\d{6}Z\r?$/DTSTAMP:yyyymmddThhmmssZ/

testing/tests/regression-suite/2606-REPORT-freebusy-no-start.result

@@ -0,0 +1,21 @@
+HTTP/1.1 200 OK
+Date: Dow, 01 Jan 2000 00:00:00 GMT
+DAV: 1, 2, 3, access-control, calendar-access, calendar-schedule
+DAV: extended-mkcol, bind, addressbook, calendar-auto-schedule, calendar-proxy
+Content-Length: 398
+Content-Type: text/calendar;charset=UTF-8
+
+BEGIN:VCALENDAR
+PRODID:-//davical.org//NONSGML AWL Calendar//EN
+VERSION:2.0
+CALSCALE:GREGORIAN
+BEGIN:VFREEBUSY
+DTSTAMP:yyyymmddThhmmssZ
+DTSTART:20230416T140000Z
+DTEND:20250415T140000Z
+FREEBUSY:20230416T210000Z/20230416T212500Z
+FREEBUSY:20230418T230000Z/20230418T232500Z
+FREEBUSY:20230419T210000Z/20230419T212500Z
+FREEBUSY:20230420T210000Z/20230420T212500Z
+END:VFREEBUSY
+END:VCALENDAR

testing/tests/regression-suite/2606-REPORT-freebusy-no-start.test

@@ -0,0 +1,21 @@
+#
+P
+# Request a REPORT with only start set, end should be sometime in the future.
+#
+TYPE=REPORT
+URL=http://regression.host/caldav.php/user1/291-test-fb-rr-changes/
+HEADER=Accept: text/calendar
+HEADER=Content-Type: text/xml
+HEADER=Depth: 1
+HEAD
+
+AUTH=user4:user4
+
+BEGINDATA
+<?xml version="1.0" encoding="utf-8" ?>
+<C:free-busy-query xmlns:C="urn:ietf:params:xml:ns:caldav">
+  <C:time-range start="20230416T140000Z" />
+</C:free-busy-query>
+ENDDATA
+
+REPLACE=/^DTSTAMP:\d{8}T\d{6}Z\r?$/DTSTAMP:yyyymmddThhmmssZ/

testing/tests/regression-suite/2607-REPORT-freebusy-no-end.result

@@ -0,0 +1,21 @@
+HTTP/1.1 200 OK
+Date: Dow, 01 Jan 2000 00:00:00 GMT
+DAV: 1, 2, 3, access-control, calendar-access, calendar-schedule
+DAV: extended-mkcol, bind, addressbook, calendar-auto-schedule, calendar-proxy
+Content-Length: 398
+Content-Type: text/calendar;charset=UTF-8
+
+BEGIN:VCALENDAR
+PRODID:-//davical.org//NONSGML AWL Calendar//EN
+VERSION:2.0
+CALSCALE:GREGORIAN
+BEGIN:VFREEBUSY
+DTSTAMP:yyyymmddThhmmssZ
+DTSTART:20220421T220000Z
+DTEND:20230421T220000Z
+FREEBUSY:20230416T210000Z/20230416T212500Z
+FREEBUSY:20230418T230000Z/20230418T232500Z
+FREEBUSY:20230419T210000Z/20230419T212500Z
+FREEBUSY:20230420T210000Z/20230420T212500Z
+END:VFREEBUSY
+END:VCALENDAR

testing/tests/regression-suite/2607-REPORT-freebusy-no-end.test

@@ -0,0 +1,21 @@
+#
+P
+# Request a REPORT with only end set, start should be sometime in the past.
+#
+TYPE=REPORT
+URL=http://regression.host/caldav.php/user1/291-test-fb-rr-changes/
+HEADER=Accept: text/calendar
+HEADER=Content-Type: text/xml
+HEADER=Depth: 1
+HEAD
+
+AUTH=user4:user4
+
+BEGINDATA
+<?xml version="1.0" encoding="utf-8" ?>
+<C:free-busy-query xmlns:C="urn:ietf:params:xml:ns:caldav">
+  <C:time-range end="20230421T220000Z" />
+</C:free-busy-query>
+ENDDATA
+
+REPLACE=/^DTSTAMP:\d{8}T\d{6}Z\r?$/DTSTAMP:yyyymmddThhmmssZ/