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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;
use FG\ASN1\Exception\ParserException;
use FG\ASN1\Universal\BitString;
use FG\ASN1\Universal\Boolean;
use FG\ASN1\Universal\Enumerated;
use FG\ASN1\Universal\GeneralizedTime;
use FG\ASN1\Universal\Integer;
use FG\ASN1\Universal\NullObject;
use FG\ASN1\Universal\ObjectIdentifier;
use FG\ASN1\Universal\RelativeObjectIdentifier;
use FG\ASN1\Universal\OctetString;
use FG\ASN1\Universal\Sequence;
use FG\ASN1\Universal\Set;
use FG\ASN1\Universal\UTCTime;
use FG\ASN1\Universal\IA5String;
use FG\ASN1\Universal\PrintableString;
use FG\ASN1\Universal\NumericString;
use FG\ASN1\Universal\UTF8String;
use FG\ASN1\Universal\UniversalString;
use FG\ASN1\Universal\CharacterString;
use FG\ASN1\Universal\GeneralString;
use FG\ASN1\Universal\VisibleString;
use FG\ASN1\Universal\GraphicString;
use FG\ASN1\Universal\BMPString;
use FG\ASN1\Universal\T61String;
use FG\ASN1\Universal\ObjectDescriptor;
use FG\Utility\BigInteger;
use LogicException;
/**
* Class ASNObject is the base class for all concrete ASN.1 objects.
*/
abstract class ASNObject implements Parsable
{
private $contentLength;
private $nrOfLengthOctets;
/**
* Must return the number of octets of the content part.
*
* @return int
*/
abstract protected function calculateContentLength();
/**
* Encode the object using DER encoding.
*
* @see http://en.wikipedia.org/wiki/X.690#DER_encoding
*
* @return string the binary representation of an objects value
*/
abstract protected function getEncodedValue();
/**
* Return the content of this object in a non encoded form.
* This can be used to print the value in human readable form.
*
* @return mixed
*/
abstract public function getContent();
/**
* Return the object type octet.
* This should use the class constants of Identifier.
*
* @see Identifier
*
* @return int
*/
abstract public function getType();
/**
* Returns all identifier octets. If an inheriting class models a tag with
* the long form identifier format, it MUST reimplement this method to
* return all octets of the identifier.
*
* @throws LogicException If the identifier format is long form
*
* @return string Identifier as a set of octets
*/
public function getIdentifier()
{
$firstOctet = $this->getType();
if (Identifier::isLongForm($firstOctet)) {
throw new LogicException(sprintf('Identifier of %s uses the long form and must therefor override "ASNObject::getIdentifier()".', get_class($this)));
}
return chr($firstOctet);
}
/**
* Encode this object using DER encoding.
*
* @return string the full binary representation of the complete object
*/
public function getBinary()
{
$result = $this->getIdentifier();
$result .= $this->createLengthPart();
$result .= $this->getEncodedValue();
return $result;
}
private function createLengthPart()
{
$contentLength = $this->getContentLength();
$nrOfLengthOctets = $this->getNumberOfLengthOctets($contentLength);
if ($nrOfLengthOctets == 1) {
return chr($contentLength);
} else {
// the first length octet determines the number subsequent length octets
$lengthOctets = chr(0x80 | ($nrOfLengthOctets - 1));
for ($shiftLength = 8 * ($nrOfLengthOctets - 2); $shiftLength >= 0; $shiftLength -= 8) {
$lengthOctets .= chr($contentLength >> $shiftLength);
}
return $lengthOctets;
}
}
protected function getNumberOfLengthOctets($contentLength = null)
{
if (!isset($this->nrOfLengthOctets)) {
if ($contentLength == null) {
$contentLength = $this->getContentLength();
}
$this->nrOfLengthOctets = 1;
if ($contentLength > 127) {
do { // long form
$this->nrOfLengthOctets++;
$contentLength = $contentLength >> 8;
} while ($contentLength > 0);
}
}
return $this->nrOfLengthOctets;
}
protected function getContentLength()
{
if (!isset($this->contentLength)) {
$this->contentLength = $this->calculateContentLength();
}
return $this->contentLength;
}
protected function setContentLength($newContentLength)
{
$this->contentLength = $newContentLength;
$this->getNumberOfLengthOctets($newContentLength);
}
/**
* Returns the length of the whole object (including the identifier and length octets).
*/
public function getObjectLength()
{
$nrOfIdentifierOctets = strlen($this->getIdentifier());
$contentLength = $this->getContentLength();
$nrOfLengthOctets = $this->getNumberOfLengthOctets($contentLength);
return $nrOfIdentifierOctets + $nrOfLengthOctets + $contentLength;
}
public function __toString()
{
return $this->getContent();
}
/**
* Returns the name of the ASN.1 Type of this object.
*
* @see Identifier::getName()
*/
public function getTypeName()
{
return Identifier::getName($this->getType());
}
/**
* @param string $binaryData
* @param int $offsetIndex
*
* @throws ParserException
*
* @return \FG\ASN1\ASNObject
*/
public static function fromBinary(&$binaryData, &$offsetIndex = 0)
{
if (strlen($binaryData) <= $offsetIndex) {
throw new ParserException('Can not parse binary from data: Offset index larger than input size', $offsetIndex);
}
$identifierOctet = ord($binaryData[$offsetIndex]);
if (Identifier::isContextSpecificClass($identifierOctet) && Identifier::isConstructed($identifierOctet)) {
return ExplicitlyTaggedObject::fromBinary($binaryData, $offsetIndex);
}
switch ($identifierOctet) {
case Identifier::BITSTRING:
return BitString::fromBinary($binaryData, $offsetIndex);
case Identifier::BOOLEAN:
return Boolean::fromBinary($binaryData, $offsetIndex);
case Identifier::ENUMERATED:
return Enumerated::fromBinary($binaryData, $offsetIndex);
case Identifier::INTEGER:
return Integer::fromBinary($binaryData, $offsetIndex);
case Identifier::NULL:
return NullObject::fromBinary($binaryData, $offsetIndex);
case Identifier::OBJECT_IDENTIFIER:
return ObjectIdentifier::fromBinary($binaryData, $offsetIndex);
case Identifier::RELATIVE_OID:
return RelativeObjectIdentifier::fromBinary($binaryData, $offsetIndex);
case Identifier::OCTETSTRING:
return OctetString::fromBinary($binaryData, $offsetIndex);
case Identifier::SEQUENCE:
return Sequence::fromBinary($binaryData, $offsetIndex);
case Identifier::SET:
return Set::fromBinary($binaryData, $offsetIndex);
case Identifier::UTC_TIME:
return UTCTime::fromBinary($binaryData, $offsetIndex);
case Identifier::GENERALIZED_TIME:
return GeneralizedTime::fromBinary($binaryData, $offsetIndex);
case Identifier::IA5_STRING:
return IA5String::fromBinary($binaryData, $offsetIndex);
case Identifier::PRINTABLE_STRING:
return PrintableString::fromBinary($binaryData, $offsetIndex);
case Identifier::NUMERIC_STRING:
return NumericString::fromBinary($binaryData, $offsetIndex);
case Identifier::UTF8_STRING:
return UTF8String::fromBinary($binaryData, $offsetIndex);
case Identifier::UNIVERSAL_STRING:
return UniversalString::fromBinary($binaryData, $offsetIndex);
case Identifier::CHARACTER_STRING:
return CharacterString::fromBinary($binaryData, $offsetIndex);
case Identifier::GENERAL_STRING:
return GeneralString::fromBinary($binaryData, $offsetIndex);
case Identifier::VISIBLE_STRING:
return VisibleString::fromBinary($binaryData, $offsetIndex);
case Identifier::GRAPHIC_STRING:
return GraphicString::fromBinary($binaryData, $offsetIndex);
case Identifier::BMP_STRING:
return BMPString::fromBinary($binaryData, $offsetIndex);
case Identifier::T61_STRING:
return T61String::fromBinary($binaryData, $offsetIndex);
case Identifier::OBJECT_DESCRIPTOR:
return ObjectDescriptor::fromBinary($binaryData, $offsetIndex);
default:
// At this point the identifier may be >1 byte.
if (Identifier::isConstructed($identifierOctet)) {
return new UnknownConstructedObject($binaryData, $offsetIndex);
} else {
$identifier = self::parseBinaryIdentifier($binaryData, $offsetIndex);
$lengthOfUnknownObject = self::parseContentLength($binaryData, $offsetIndex);
$offsetIndex += $lengthOfUnknownObject;
return new UnknownObject($identifier, $lengthOfUnknownObject);
}
}
}
protected static function parseIdentifier($identifierOctet, $expectedIdentifier, $offsetForExceptionHandling)
{
if (is_string($identifierOctet) || is_numeric($identifierOctet) == false) {
$identifierOctet = ord($identifierOctet);
}
if ($identifierOctet != $expectedIdentifier) {
$message = 'Can not create an '.Identifier::getName($expectedIdentifier).' from an '.Identifier::getName($identifierOctet);
throw new ParserException($message, $offsetForExceptionHandling);
}
}
protected static function parseBinaryIdentifier($binaryData, &$offsetIndex)
{
if (strlen($binaryData) <= $offsetIndex) {
throw new ParserException('Can not parse identifier from data: Offset index larger than input size', $offsetIndex);
}
$identifier = $binaryData[$offsetIndex++];
if (Identifier::isLongForm(ord($identifier)) == false) {
return $identifier;
}
while (true) {
if (strlen($binaryData) <= $offsetIndex) {
throw new ParserException('Can not parse identifier (long form) from data: Offset index larger than input size', $offsetIndex);
}
$nextOctet = $binaryData[$offsetIndex++];
$identifier .= $nextOctet;
if ((ord($nextOctet) & 0x80) === 0) {
// the most significant bit is 0 to we have reached the end of the identifier
break;
}
}
return $identifier;
}
protected static function parseContentLength(&$binaryData, &$offsetIndex, $minimumLength = 0)
{
if (strlen($binaryData) <= $offsetIndex) {
throw new ParserException('Can not parse content length from data: Offset index larger than input size', $offsetIndex);
}
$contentLength = ord($binaryData[$offsetIndex++]);
if (($contentLength & 0x80) != 0) {
// bit 8 is set -> this is the long form
$nrOfLengthOctets = $contentLength & 0x7F;
$contentLength = BigInteger::create(0x00);
for ($i = 0; $i < $nrOfLengthOctets; $i++) {
if (strlen($binaryData) <= $offsetIndex) {
throw new ParserException('Can not parse content length (long form) from data: Offset index larger than input size', $offsetIndex);
}
$contentLength = $contentLength->shiftLeft(8)->add(ord($binaryData[$offsetIndex++]));
}
if ($contentLength->compare(PHP_INT_MAX) > 0) {
throw new ParserException("Can not parse content length from data: length > maximum integer", $offsetIndex);
}
$contentLength = $contentLength->toInteger();
}
if ($contentLength < $minimumLength) {
throw new ParserException('A '.get_called_class()." should have a content length of at least {$minimumLength}. Extracted length was {$contentLength}", $offsetIndex);
}
$lenDataRemaining = strlen($binaryData) - $offsetIndex;
if ($lenDataRemaining < $contentLength) {
throw new ParserException("Content length {$contentLength} exceeds remaining data length {$lenDataRemaining}", $offsetIndex);
}
return $contentLength;
}
}
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