includes/Rest/HeaderParser/HttpDate.php
<?php
namespace MediaWiki\Rest\HeaderParser;
/**
* This is a parser for "HTTP-date" as defined by RFC 7231.
*
* Normally in MediaWiki, dates in HTTP headers are converted using
* ConvertibleTimestamp or strtotime(), and this is encouraged by RFC 7231:
*
* "Recipients of timestamp values are encouraged to be robust in parsing
* timestamps unless otherwise restricted by the field definition."
*
* In the case of If-Modified-Since, we are in fact otherwise restricted, since
* RFC 7232 says:
*
* "A recipient MUST ignore the If-Modified-Since header field if the
* received field-value is not a valid HTTP-date"
*
* So it is not correct to use strtotime() or ConvertibleTimestamp to parse
* If-Modified-Since.
*/
class HttpDate extends HeaderParserBase {
private static $dayNames = [
'Mon' => true,
'Tue' => true,
'Wed' => true,
'Thu' => true,
'Fri' => true,
'Sat' => true,
'Sun' => true
];
private static $monthsByName = [
'Jan' => 1,
'Feb' => 2,
'Mar' => 3,
'Apr' => 4,
'May' => 5,
'Jun' => 6,
'Jul' => 7,
'Aug' => 8,
'Sep' => 9,
'Oct' => 10,
'Nov' => 11,
'Dec' => 12,
];
private static $dayNamesLong = [
'Monday',
'Tuesday',
'Wednesday',
'Thursday',
'Friday',
'Saturday',
'Sunday',
];
/** @var string */
private $dayName;
/** @var string */
private $day;
/** @var int */
private $month;
/** @var int */
private $year;
/** @var string */
private $hour;
/** @var string */
private $minute;
/** @var string */
private $second;
/**
* Parse an HTTP-date string
*
* @param string $dateString
* @return int|null The UNIX timestamp, or null if the date was invalid
*/
public static function parse( $dateString ) {
$parser = new self( $dateString );
if ( $parser->execute() ) {
return $parser->getUnixTime();
} else {
return null;
}
}
/**
* A convenience function to convert a UNIX timestamp to the preferred
* IMF-fixdate format for HTTP header output.
*
* @param int $unixTime
* @return false|string
*/
public static function format( $unixTime ) {
return gmdate( 'D, d M Y H:i:s \G\M\T', $unixTime );
}
/**
* Private constructor. Use the public static functions for public access.
*
* @param string $input
*/
private function __construct( $input ) {
$this->setInput( $input );
}
/**
* Parse the input string
*
* @return bool True for success
*/
private function execute() {
$this->pos = 0;
try {
$this->consumeFixdate();
$this->assertEnd();
return true;
} catch ( HeaderParserError $e ) {
}
$this->pos = 0;
try {
$this->consumeRfc850Date();
$this->assertEnd();
return true;
} catch ( HeaderParserError $e ) {
}
$this->pos = 0;
try {
$this->consumeAsctimeDate();
$this->assertEnd();
return true;
} catch ( HeaderParserError $e ) {
}
return false;
}
/**
* Execute the IMF-fixdate rule, or throw an exception
*
* @throws HeaderParserError
*/
private function consumeFixdate() {
$this->consumeDayName();
$this->consumeString( ', ' );
$this->consumeDate1();
$this->consumeString( ' ' );
$this->consumeTimeOfDay();
$this->consumeString( ' GMT' );
}
/**
* Execute the day-name rule, and capture the result.
*
* @throws HeaderParserError
*/
private function consumeDayName() {
$next3 = substr( $this->input, $this->pos, 3 );
if ( isset( self::$dayNames[$next3] ) ) {
$this->dayName = $next3;
$this->pos += 3;
} else {
$this->error( 'expected day-name' );
}
}
/**
* Execute the date1 rule
*
* @throws HeaderParserError
*/
private function consumeDate1() {
$this->consumeDay();
$this->consumeString( ' ' );
$this->consumeMonth();
$this->consumeString( ' ' );
$this->consumeYear();
}
/**
* Execute the day rule, and capture the result.
*
* @throws HeaderParserError
*/
private function consumeDay() {
$this->day = $this->consumeFixedDigits( 2 );
}
/**
* Execute the month rule, and capture the result
*
* @throws HeaderParserError
*/
private function consumeMonth() {
$next3 = substr( $this->input, $this->pos, 3 );
if ( isset( self::$monthsByName[$next3] ) ) {
$this->month = self::$monthsByName[$next3];
$this->pos += 3;
} else {
$this->error( 'expected month' );
}
}
/**
* Execute the year rule, and capture the result
*
* @throws HeaderParserError
*/
private function consumeYear() {
$this->year = (int)$this->consumeFixedDigits( 4 );
}
/**
* Execute the time-of-day rule
* @throws HeaderParserError
*/
private function consumeTimeOfDay() {
$this->hour = $this->consumeFixedDigits( 2 );
$this->consumeString( ':' );
$this->minute = $this->consumeFixedDigits( 2 );
$this->consumeString( ':' );
$this->second = $this->consumeFixedDigits( 2 );
}
/**
* Execute the rfc850-date rule
*
* @throws HeaderParserError
*/
private function consumeRfc850Date() {
$this->consumeDayNameLong();
$this->consumeString( ', ' );
$this->consumeDate2();
$this->consumeString( ' ' );
$this->consumeTimeOfDay();
$this->consumeString( ' GMT' );
}
/**
* Execute the date2 rule.
*
* @throws HeaderParserError
*/
private function consumeDate2() {
$this->consumeDay();
$this->consumeString( '-' );
$this->consumeMonth();
$this->consumeString( '-' );
$year = $this->consumeFixedDigits( 2 );
// RFC 2626 section 11.2
$currentYear = (int)gmdate( 'Y' );
$startOfCentury = (int)round( $currentYear, -2 );
$this->year = $startOfCentury + intval( $year );
$pivot = $currentYear + 50;
if ( $this->year > $pivot ) {
$this->year -= 100;
}
}
/**
* Execute the day-name-l rule
*
* @throws HeaderParserError
*/
private function consumeDayNameLong() {
foreach ( self::$dayNamesLong as $dayName ) {
if ( substr_compare( $this->input, $dayName, $this->pos, strlen( $dayName ) ) === 0 ) {
$this->dayName = substr( $dayName, 0, 3 );
$this->pos += strlen( $dayName );
return;
}
}
$this->error( 'expected day-name-l' );
}
/**
* Execute the asctime-date rule
*
* @throws HeaderParserError
*/
private function consumeAsctimeDate() {
$this->consumeDayName();
$this->consumeString( ' ' );
$this->consumeDate3();
$this->consumeString( ' ' );
$this->consumeTimeOfDay();
$this->consumeString( ' ' );
$this->consumeYear();
}
/**
* Execute the date3 rule
*
* @throws HeaderParserError
*/
private function consumeDate3() {
$this->consumeMonth();
$this->consumeString( ' ' );
if ( ( $this->input[$this->pos] ?? '' ) === ' ' ) {
$this->pos++;
$this->day = '0' . $this->consumeFixedDigits( 1 );
} else {
$this->day = $this->consumeFixedDigits( 2 );
}
}
/**
* Convert the captured results to a UNIX timestamp.
* This should only be called after parsing succeeds.
*
* @return int
*/
private function getUnixTime() {
return gmmktime( (int)$this->hour, (int)$this->minute, (int)$this->second,
$this->month, (int)$this->day, $this->year );
}
}