timezone_name_from_abbr() not recognizing correctly

[php_nub_qq]

Basically my website is worldwide and I need to be able to detect users' time zones and display accurate times. I have this really neat script which used to work flawlessly well until now. It needs a timezone offset which I fetch with javascript and pass through a cookie.

if(!empty($_COOKIE['tz']) && $_COOKIE['tz']>=-12 && $_COOKIE['tz']<=13){

	$offset = $_COOKIE['tz'];

	$tz = timezone_name_from_abbr(null, $offset * 3600, true);

	if($tz === false) $tz = timezone_name_from_abbr(null, $offset * 3600, false);

	date_default_timezone_set($tz);

}else{

	date_default_timezone_set('UTC');

}

The problem is that currently the timezone I'm testing in is Europe/Helsinki, which is UTC+2 (without daylight savings), but for some reason timezone_name_from_abbr() decides 2*3600 is Europe/Paris. I'm really bad with dates and time zones, I desperately need help, please!

[Barand]

With daylight savings param = true, offset and timezones are

1 : Europe/London
2 : Europe/Paris
3 : Europe/Helsinki
4 : Europe/Moscow

With the dst parameter = false

1 : Europe/Paris
2 : Europe/Helsinki
3 : Europe/Moscow
4 : Asia/Dubai