Improve handling of unknown timezone definitions (should fix #333)

src/at/bitfire/davdroid/resource/Event.java

@@ -352,15 +352,17 @@ public class Event extends Resource {
 		date.setTimeZone(tzRegistry.getTimeZone(localTZ));
 	}
 
-	public static String TimezoneDefToTzId(String timezoneDef) {
+	public static String TimezoneDefToTzId(String timezoneDef) throws IllegalArgumentException {
 		try {
-			CalendarBuilder builder = new CalendarBuilder();
-			net.fortuna.ical4j.model.Calendar cal = builder.build(new StringReader(timezoneDef));
-			VTimeZone timezone = (VTimeZone)cal.getComponent(VTimeZone.VTIMEZONE);
-			return timezone.getTimeZoneId().getValue();
+			if (timezoneDef != null) {
+				CalendarBuilder builder = new CalendarBuilder();
+				net.fortuna.ical4j.model.Calendar cal = builder.build(new StringReader(timezoneDef));
+				VTimeZone timezone = (VTimeZone)cal.getComponent(VTimeZone.VTIMEZONE);
+				return timezone.getTimeZoneId().getValue();
+			}
 		} catch (Exception ex) {
 			Log.w(TAG, "Can't understand time zone definition", ex);
 		}
-		return null;
+		throw new IllegalArgumentException();
 	}
 }

src/at/bitfire/davdroid/webdav/WebDavResource.java

@@ -536,7 +536,10 @@ public class WebDavResource {
 							properties.put(Property.COLOR, prop.calendarColor.getColor());
 						
 						if (prop.calendarTimezone != null)
-							properties.put(Property.TIMEZONE, Event.TimezoneDefToTzId(prop.calendarTimezone.getTimezone()));
+							try {
+								properties.put(Property.TIMEZONE, Event.TimezoneDefToTzId(prop.calendarTimezone.getTimezone()));
+							} catch(IllegalArgumentException e) {
+							}
 						
 						if (prop.supportedCalendarComponentSet != null) {
 							supportedComponents = new LinkedList<String>();

test/src/at/bitfire/davdroid/resource/test/EventTest.java

@@ -73,6 +73,47 @@ public class EventTest extends InstrumentationTestCase {
 		assertEquals(Time.TIMEZONE_UTC, eAllDay0Sec.getDtEndTzID());
 	}
 	
+	public void testTimezoneDefToTzId() {
+		final String VTIMEZONE_SAMPLE =		// taken from RFC 4791, 5.2.2. CALDAV:calendar-timezone Property 
+				"BEGIN:VCALENDAR\n" + 
+				"PRODID:-//Example Corp.//CalDAV Client//EN\n" + 
+				"VERSION:2.0\n" + 
+				"BEGIN:VTIMEZONE\n" + 
+				"TZID:US-Eastern\n" + 
+				"LAST-MODIFIED:19870101T000000Z\n" + 
+				"BEGIN:STANDARD\n" + 
+				"DTSTART:19671029T020000\n" + 
+				"RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10\n" + 
+				"TZOFFSETFROM:-0400\n" + 
+				"TZOFFSETTO:-0500\n" + 
+				"TZNAME:Eastern Standard Time (US & Canada)\n" + 
+				"END:STANDARD\n" + 
+				"BEGIN:DAYLIGHT\n" + 
+				"DTSTART:19870405T020000\n" + 
+				"RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4\n" + 
+				"TZOFFSETFROM:-0500\n" + 
+				"TZOFFSETTO:-0400\n" + 
+				"TZNAME:Eastern Daylight Time (US & Canada)\n" + 
+				"END:DAYLIGHT\n" + 
+				"END:VTIMEZONE\n" + 
+				"END:VCALENDAR";
+		assertEquals("US-Eastern", Event.TimezoneDefToTzId(VTIMEZONE_SAMPLE));
+		
+		try {
+			Event.TimezoneDefToTzId(null);
+			fail();
+		} catch(IllegalArgumentException e) {
+			assert(true);
+		}
+		
+		try {
+			Event.TimezoneDefToTzId("/* invalid content */");
+			fail();
+		} catch(IllegalArgumentException e) {
+			assert(true);
+		}
+	}
+	
 	
 	protected Event parseCalendar(String fname) throws IOException, InvalidResourceException {
 		@Cleanup InputStream in = assetMgr.open(fname, AssetManager.ACCESS_STREAMING);