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<?php
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namespace Aws\S3;
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use Aws\Api\Parser\AbstractParser;
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use Aws\Api\Service;
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use Aws\Api\StructureShape;
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use Aws\CommandInterface;
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use Aws\S3\Exception\S3Exception;
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use Psr\Http\Message\ResponseInterface;
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use Psr\Http\Message\StreamInterface;
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/**
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 * @internal Decorates a parser for the S3 service to validate the response checksum.
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 */
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class ValidateResponseChecksumParser extends AbstractParser
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{
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    use CalculatesChecksumTrait;
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    /**
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     * @param callable $parser Parser to wrap.
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     */
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    public function __construct(callable $parser, Service $api)
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    {
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        $this->api = $api;
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        $this->parser = $parser;
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    }
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    public function __invoke(
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        CommandInterface $command,
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        ResponseInterface $response
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    ) {
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        $fn = $this->parser;
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        $result = $fn($command, $response);
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        //Skip this middleware if the operation doesn't have an httpChecksum
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        $op = $this->api->getOperation($command->getName());
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        $checksumInfo = isset($op['httpChecksum'])
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            ? $op['httpChecksum']
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            : [];
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        if (empty($checksumInfo)) {
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            return $result;
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        }
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        //Skip this middleware if the operation doesn't send back a checksum, or the user doesn't opt in
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        $checksumModeEnabledMember = isset($checksumInfo['requestValidationModeMember'])
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            ? $checksumInfo['requestValidationModeMember']
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            : "";
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        $checksumModeEnabled = isset($command[$checksumModeEnabledMember])
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            ? $command[$checksumModeEnabledMember]
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            : "";
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        $responseAlgorithms = isset($checksumInfo['responseAlgorithms'])
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            ? $checksumInfo['responseAlgorithms']
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            : [];
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        if (empty($responseAlgorithms)
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            || strtolower($checksumModeEnabled) !== "enabled"
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        ) {
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            return $result;
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        }
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        if (extension_loaded('awscrt')) {
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            $checksumPriority = ['CRC32C', 'CRC32', 'SHA1', 'SHA256'];
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        } else {
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            $checksumPriority = ['CRC32', 'SHA1', 'SHA256'];
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        }
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        $checksumsToCheck = array_intersect($responseAlgorithms, $checksumPriority);
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        $checksumValidationInfo = $this->validateChecksum($checksumsToCheck, $response);
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        if ($checksumValidationInfo['status'] == "SUCCEEDED") {
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            $result['ChecksumValidated'] = $checksumValidationInfo['checksum'];
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        } else if ($checksumValidationInfo['status'] == "FAILED"){
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            //Ignore failed validations on GetObject if it's a multipart get which returned a full multipart object
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            if ($command->getName() == "GetObject"
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                && !empty($checksumValidationInfo['checksumHeaderValue'])
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            ) {
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                $headerValue = $checksumValidationInfo['checksumHeaderValue'];
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                $lastDashPos = strrpos($headerValue, '-');
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                $endOfChecksum = substr($headerValue, $lastDashPos + 1);
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                if (is_numeric($endOfChecksum)
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                    && intval($endOfChecksum) > 1
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                    && intval($endOfChecksum) < 10000) {
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                    return $result;
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                }
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            }
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            throw new S3Exception(
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                "Calculated response checksum did not match the expected value",
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                $command
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            );
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        }
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        return $result;
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    }
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    public function parseMemberFromStream(
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        StreamInterface $stream,
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        StructureShape $member,
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        $response
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    ) {
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        return $this->parser->parseMemberFromStream($stream, $member, $response);
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    }
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    /**
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     * @param $checksumPriority
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     * @param ResponseInterface $response
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     */
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    public function validateChecksum($checksumPriority, ResponseInterface $response)
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    {
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        $checksumToValidate = $this->chooseChecksumHeaderToValidate(
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            $checksumPriority,
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            $response
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        );
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        $validationStatus = "SKIPPED";
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        $checksumHeaderValue = null;
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        if (!empty($checksumToValidate)) {
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            $checksumHeaderValue = $response->getHeader(
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                'x-amz-checksum-' . $checksumToValidate
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            );
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            if (isset($checksumHeaderValue)) {
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                $checksumHeaderValue = $checksumHeaderValue[0];
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                $calculatedChecksumValue = $this->getEncodedValue(
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                    $checksumToValidate,
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                    $response->getBody()
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                );
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                $validationStatus = $checksumHeaderValue == $calculatedChecksumValue
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                    ? "SUCCEEDED"
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                    : "FAILED";
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            }
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        }
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        return [
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            "status" => $validationStatus,
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            "checksum" => $checksumToValidate,
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            "checksumHeaderValue" => $checksumHeaderValue,
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        ];
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    }
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    /**
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     * @param $checksumPriority
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     * @param ResponseInterface $response
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     */
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    public function chooseChecksumHeaderToValidate(
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        $checksumPriority,
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        ResponseInterface $response
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    ) {
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        foreach ($checksumPriority as $checksum) {
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            $checksumHeader = 'x-amz-checksum-' . $checksum;
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            if ($response->hasHeader($checksumHeader)) {
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                return $checksum;
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            }
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        }
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        return null;
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    }
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}