Occasional NPEs from ERXTimeZoneDetector

[paulhoadley]

I started a mailing list thread on this issue back in April. I’m seeing occasional NPEs from ERXTimeZoneDetector like this:

java.lang.NullPointerException: timeZone must not be set to null
    at er.extensions.appserver.ERXSession.setTimeZone(ERXSession.java:810)
    at er.extensions.components.ERXTimeZoneDetector.takeValuesFromRequest(ERXTimeZoneDetector.java:148)
    at com.webobjects.appserver._private.WOComponentReference.takeValuesFromRequest(WOComponentReference.java:119)

ERXSession.setTimeZone() doesn’t like nulls, and that’s fair enough. It’s being called from here:

public void takeValuesFromRequest(WORequest request, WOContext context) {
    super.takeValuesFromRequest(request, context);
    if (shouldPostData() && request.formValueForKey(TIMEZONE_DATA_KEY) != null) {
        ...
        TimeZone tz = zoneWithRawOffset(rawOffset, dst, southern);
        session.setTimeZone(tz);
    }
}

That is, when ERXTimeZoneDetector thinks it’s found the TimeZone, it calls setTimeZone(), except sometimes tz is null. In the resulting log output, ERXBasicBrowser is suggesting the culprit is usually IE 8, sometimes IE 9 and IE 7. I don’t know whether this is a legitimate app user, or someone browsing the login page, or a bot.

It turns out that detectedTimeZone is consistently “180,1,0”. It’s the DST parameter that’s causing the problem. zonesWithRawOffset(180, true, false) returns null, but zonesWithRawOffset(180, false, false) returns an array of 27 zones. This is using a recent Java 8 release, so presumably the timezones should be quite up to date.

Again, I don't know what the root cause is here (real user with misconfigured user agent, misconfigured bot, real timezone that Java doesn't know about, bug in the detection Javascript...), but in any case I would argue that it's a bug for ERXTimeZoneDetector to call setTimeZone(tz) when it knows tz is null. I propose that ERXTimeZoneDetector guards its call to setTimeZone()with a check for null. and logs something informational if it's unable to detect the timezone. I'll submit a pull request soon.

[paulhoadley]

Fixed by #775.