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<?php
/**
* HTTP utility methods
*
* @package Sabre
* @subpackage HTTP
* @copyright Copyright (C) 2007-2012 Rooftop Solutions. All rights reserved.
* @author Evert Pot (http://www.rooftopsolutions.nl/)
* @author Paul Voegler
* @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
*/
class Sabre_HTTP_Util {
/**
* Parses a RFC2616-compatible date string
*
* This method returns false if the date is invalid
*
* @param string $dateHeader
* @return bool|DateTime
*/
static function parseHTTPDate($dateHeader) {
//RFC 2616 section 3.3.1 Full Date
//Only the format is checked, valid ranges are checked by strtotime below
$month = '(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)';
$weekday = '(Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday)';
$wkday = '(Mon|Tue|Wed|Thu|Fri|Sat|Sun)';
$time = '[0-2]\d(\:[0-5]\d){2}';
$date3 = $month . ' ([1-3]\d| \d)';
$date2 = '[0-3]\d\-' . $month . '\-\d\d';
//4-digit year cannot begin with 0 - unix timestamp begins in 1970
$date1 = '[0-3]\d ' . $month . ' [1-9]\d{3}';
//ANSI C's asctime() format
//4-digit year cannot begin with 0 - unix timestamp begins in 1970
$asctime_date = $wkday . ' ' . $date3 . ' ' . $time . ' [1-9]\d{3}';
//RFC 850, obsoleted by RFC 1036
$rfc850_date = $weekday . ', ' . $date2 . ' ' . $time . ' GMT';
//RFC 822, updated by RFC 1123
$rfc1123_date = $wkday . ', ' . $date1 . ' ' . $time . ' GMT';
//allowed date formats by RFC 2616
$HTTP_date = "($rfc1123_date|$rfc850_date|$asctime_date)";
//allow for space around the string and strip it
$dateHeader = trim($dateHeader, ' ');
if (!preg_match('/^' . $HTTP_date . '$/', $dateHeader))
return false;
//append implicit GMT timezone to ANSI C time format
if (strpos($dateHeader, ' GMT') === false)
$dateHeader .= ' GMT';
$realDate = strtotime($dateHeader);
//strtotime can return -1 or false in case of error
if ($realDate !== false && $realDate >= 0)
return new DateTime('@' . $realDate, new DateTimeZone('UTC'));
}
/**
* Transforms a DateTime object to HTTP's most common date format.
*
* We're serializing it as the RFC 1123 date, which, for HTTP must be
* specified as GMT.
*
* @param DateTime $dateTime
* @return string
*/
static function toHTTPDate(DateTime $dateTime) {
// We need to clone it, as we don't want to affect the existing
// DateTime.
$dateTime = clone $dateTime;
$dateTime->setTimeZone(new DateTimeZone('GMT'));
return $dateTime->format('D, d M Y H:i:s \G\M\T');
}
}
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