<?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.
 */

require_once __DIR__.'/../vendor/autoload.php';
require_once 'shared.php';

use FG\ASN1\OID;
use FG\ASN1\Object;
use FG\ASN1\Identifier;
use FG\ASN1\Universal\ObjectIdentifier;
use FG\ASN1\Universal\OctetString;
use FG\ASN1\Universal\Sequence;

$base64 = 'MIIINTCCBh2gAwIBAgIQbVVJc10C7UUjfYRHQ//7nTANBgkqhkiG9w0BAQsFADB0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';

try {
    $binaryData = base64_decode($base64);
    //hexdump($binaryData, false);

    $rootObject = Object::fromBinary($binaryData);
    //printObject($rootObject);

    // first navigate to the certificate extensions
    // (see ITU-T X.509 section 7 "Public-keys and public-key certificates" for cert structure)
    /* @var Sequence $rootObject */
    assert($rootObject->getType() == Identifier::SEQUENCE);
    $topLevelContainer = $rootObject->getChildren();
    $certificateInfo = $topLevelContainer[0];

    /* @var Sequence $certificateInfo */
    assert($certificateInfo->getType() == Identifier::SEQUENCE);

    // there need to be at least 8 child elements if the certificate extensions field is present
    assert($certificateInfo->getNumberofChildren() >= 8);
    $certInfoFields = $certificateInfo->getChildren();
    $certExtensions = $certInfoFields[7];

    // check if this is really the certificate extensions sequence
    /* @var \FG\ASN1\Object $certExtensions */
    $certExtensionsType = $certExtensions->getType();
    assert(Identifier::isContextSpecificClass($certExtensionsType));
    assert(Identifier::getTagNumber($certExtensions->getType()) == 3);

    // this should contain a sequence of extensions
    $certExtensions = $certExtensions->getFirstChild();
    assert($certExtensions->getType() == Identifier::SEQUENCE);

    // now check all extensions and search for the SAN
    /** @var \FG\ASN1\Object $extensionSequence */
    foreach ($certExtensions as $extensionSequence) {
        assert($extensionSequence->getType() == Identifier::SEQUENCE);
        assert($extensionSequence->getNumberofChildren() >= 2);

        $extensionSequenceChildren = $extensionSequence->getChildren();
        $objectIdentifier = $extensionSequenceChildren[0];
        /* @var ObjectIdentifier $objectIdentifier */
        assert($objectIdentifier->getType() == Identifier::OBJECT_IDENTIFIER);

        if ($objectIdentifier->getContent() == OID::CERT_EXT_SUBJECT_ALT_NAME) {
            // now we have the wanted octet string
            $octetString = $extensionSequenceChildren[1];
            /* @var OctetString $octetString */
            $octetStringBinary = $octetString->getBinaryContent();

            // At this point you may want to create the sequence from the binary value of
            // the octet string and parse its structure like we did so far.
            // However a more general approach would be to understand the format of the
            // contained SAN fields and implement them in SubjectAlternativeNames.
            $sequence = Sequence::fromBinary($octetStringBinary);
            echo 'This is the parsed content of the SAN certificate extension field so far:'.PHP_EOL;
            printObject($sequence);

            // The following does not work yet because PHPASN1 SAn does only support DNS and IP
            //SubjectAlternativeNames::fromBinary($octetStringBinary);
        }
    }
} catch (\Exception $exception) {
    echo '[ERROR] Caught exception:'.PHP_EOL.$exception->getMessage().PHP_EOL;
}