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<?php
/*
* This file is part of the PHPASN1 library.
*
* Copyright © Friedrich Große <friedrich.grosse@gmail.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace FG\ASN1\Universal;
use Exception;
use FG\Utility\BigInteger;
use FG\ASN1\Exception\ParserException;
use FG\ASN1\ASNObject;
use FG\ASN1\Parsable;
use FG\ASN1\Identifier;
class Integer extends ASNObject implements Parsable
{
/** @var int */
private $value;
/**
* @param int $value
*
* @throws Exception if the value is not numeric
*/
public function __construct($value)
{
if (is_numeric($value) == false) {
throw new Exception("Invalid VALUE [{$value}] for ASN1_INTEGER");
}
$this->value = $value;
}
public function getType()
{
return Identifier::INTEGER;
}
public function getContent()
{
return $this->value;
}
protected function calculateContentLength()
{
return strlen($this->getEncodedValue());
}
protected function getEncodedValue()
{
$value = BigInteger::create($this->value, 10);
$negative = $value->compare(0) < 0;
if ($negative) {
$value = $value->absoluteValue();
$limit = 0x80;
} else {
$limit = 0x7f;
}
$mod = 0xff+1;
$values = [];
while($value->compare($limit) > 0) {
$values[] = $value->modulus($mod)->toInteger();
$value = $value->shiftRight(8);
}
$values[] = $value->modulus($mod)->toInteger();
$numValues = count($values);
if ($negative) {
for ($i = 0; $i < $numValues; $i++) {
$values[$i] = 0xff - $values[$i];
}
for ($i = 0; $i < $numValues; $i++) {
$values[$i] += 1;
if ($values[$i] <= 0xff) {
break;
}
assert($i != $numValues - 1);
$values[$i] = 0;
}
if ($values[$numValues - 1] == 0x7f) {
$values[] = 0xff;
}
}
$values = array_reverse($values);
$r = pack("C*", ...$values);
return $r;
}
private static function ensureMinimalEncoding($binaryData, $offsetIndex)
{
// All the first nine bits cannot equal 0 or 1, which would
// be non-minimal encoding for positive and negative integers respectively
if ((ord($binaryData[$offsetIndex]) == 0x00 && (ord($binaryData[$offsetIndex+1]) & 0x80) == 0) ||
(ord($binaryData[$offsetIndex]) == 0xff && (ord($binaryData[$offsetIndex+1]) & 0x80) == 0x80)) {
throw new ParserException("Integer not minimally encoded", $offsetIndex);
}
}
public static function fromBinary(&$binaryData, &$offsetIndex = 0)
{
$parsedObject = new static(0);
self::parseIdentifier($binaryData[$offsetIndex], $parsedObject->getType(), $offsetIndex++);
$contentLength = self::parseContentLength($binaryData, $offsetIndex, 1);
if ($contentLength > 1) {
self::ensureMinimalEncoding($binaryData, $offsetIndex);
}
$isNegative = (ord($binaryData[$offsetIndex]) & 0x80) != 0x00;
$number = BigInteger::create(ord($binaryData[$offsetIndex++]) & 0x7F);
for ($i = 0; $i < $contentLength - 1; $i++) {
$number = $number->multiply(0x100)->add(ord($binaryData[$offsetIndex++]));
}
if ($isNegative) {
$number = $number->subtract(BigInteger::create(2)->toPower(8 * $contentLength - 1));
}
$parsedObject = new static((string)$number);
$parsedObject->setContentLength($contentLength);
return $parsedObject;
}
}
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