Current File : /www/varak.net/nextcloud.varak.net/3rdparty/spomky-labs/pki-framework/src/ASN1/Component/Length.php
<?php
declare(strict_types=1);
namespace SpomkyLabs\Pki\ASN1\Component;
use Brick\Math\BigInteger;
use DomainException;
use LogicException;
use SpomkyLabs\Pki\ASN1\Exception\DecodeException;
use SpomkyLabs\Pki\ASN1\Feature\Encodable;
use SpomkyLabs\Pki\ASN1\Util\BigInt;
use function count;
use function mb_strlen;
use function ord;
/**
* Class to represent BER/DER length octets.
*/
final class Length implements Encodable
{
/**
* Length.
*/
private readonly BigInt $_length;
/**
* @param BigInteger|int $length Length
* @param bool $_indefinite Whether length is indefinite
*/
private function __construct(
BigInteger|int $length,
private readonly bool $_indefinite = false
) {
$this->_length = BigInt::create($length);
}
public static function create(BigInteger|int $length, bool $_indefinite = false): self
{
return new self($length, $_indefinite);
}
/**
* Decode length component from DER data.
*
* @param string $data DER encoded data
* @param null|int $offset Reference to the variable that contains offset
* into the data where to start parsing.
* Variable is updated to the offset next to the
* parsed length component. If null, start from offset 0.
*/
public static function fromDER(string $data, int &$offset = null): self
{
$idx = $offset ?? 0;
$datalen = mb_strlen($data, '8bit');
if ($idx >= $datalen) {
throw new DecodeException('Unexpected end of data while decoding length.');
}
$indefinite = false;
$byte = ord($data[$idx++]);
// bits 7 to 1
$length = (0x7f & $byte);
// long form
if ((0x80 & $byte) !== 0) {
if ($length === 0) {
$indefinite = true;
} else {
if ($idx + $length > $datalen) {
throw new DecodeException('Unexpected end of data while decoding long form length.');
}
$length = self::decodeLongFormLength($length, $data, $idx);
}
}
if (isset($offset)) {
$offset = $idx;
}
return self::create($length, $indefinite);
}
/**
* Decode length from DER.
*
* Throws an exception if length doesn't match with expected or if data doesn't contain enough bytes.
*
* Requirement of definite length is relaxed contrary to the specification (sect. 10.1).
*
* @param string $data DER data
* @param int $offset Reference to the offset variable
* @param null|int $expected Expected length, null to bypass checking
* @see self::fromDER
*/
public static function expectFromDER(string $data, int &$offset, int $expected = null): self
{
$idx = $offset;
$length = self::fromDER($data, $idx);
// if certain length was expected
if (isset($expected)) {
if ($length->isIndefinite()) {
throw new DecodeException(sprintf('Expected length %d, got indefinite.', $expected));
}
if ($expected !== $length->intLength()) {
throw new DecodeException(sprintf('Expected length %d, got %d.', $expected, $length->intLength()));
}
}
// check that enough data is available
if (! $length->isIndefinite()
&& mb_strlen($data, '8bit') < $idx + $length->intLength()) {
throw new DecodeException(
sprintf(
'Length %d overflows data, %d bytes left.',
$length->intLength(),
mb_strlen($data, '8bit') - $idx
)
);
}
$offset = $idx;
return $length;
}
public function toDER(): string
{
$bytes = [];
if ($this->_indefinite) {
$bytes[] = 0x80;
} else {
$num = $this->_length->getValue();
// long form
if ($num->isGreaterThan(127)) {
$octets = [];
for (; $num->isGreaterThan(0); $num = $num->shiftedRight(8)) {
$octets[] = BigInteger::of(0xff)->and($num)->toInt();
}
$count = count($octets);
// first octet must not be 0xff
if ($count >= 127) {
throw new DomainException('Too many length octets.');
}
$bytes[] = 0x80 | $count;
foreach (array_reverse($octets) as $octet) {
$bytes[] = $octet;
}
} // short form
else {
$bytes[] = $num->toInt();
}
}
return pack('C*', ...$bytes);
}
/**
* Get the length.
*
* @return string Length as an integer string
*/
public function length(): string
{
if ($this->_indefinite) {
throw new LogicException('Length is indefinite.');
}
return $this->_length->base10();
}
/**
* Get the length as an integer.
*/
public function intLength(): int
{
if ($this->_indefinite) {
throw new LogicException('Length is indefinite.');
}
return $this->_length->toInt();
}
/**
* Whether length is indefinite.
*/
public function isIndefinite(): bool
{
return $this->_indefinite;
}
/**
* Decode long form length.
*
* @param int $length Number of octets
* @param string $data Data
* @param int $offset reference to the variable containing offset to the data
*/
private static function decodeLongFormLength(int $length, string $data, int &$offset): BigInteger
{
// first octet must not be 0xff (spec 8.1.3.5c)
if ($length === 127) {
throw new DecodeException('Invalid number of length octets.');
}
$num = BigInteger::of(0);
while (--$length >= 0) {
$byte = ord($data[$offset++]);
$num = $num->shiftedLeft(8)
->or($byte);
}
return $num;
}
}
Mini Shell