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efrain |
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<?php
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namespace Aws;
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use Aws\Api\Service;
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use Psr\Http\Message\RequestInterface;
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/**
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* @internal Middleware that auto fills parameters with `idempotencyToken` trait
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*/
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class IdempotencyTokenMiddleware
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{
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/** @var Service */
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private $service;
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/** @var string */
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private $bytesGenerator;
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/** @var callable */
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private $nextHandler;
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/**
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* Creates a middleware that populates operation parameter
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* with trait 'idempotencyToken' enabled with a random UUIDv4
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*
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* One of following functions needs to be available
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* in order to generate random bytes used for UUID
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* (SDK will attempt to utilize function in following order):
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* - random_bytes (requires PHP 7.0 or above)
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* - openssl_random_pseudo_bytes (requires 'openssl' module enabled)
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* - mcrypt_create_iv (requires 'mcrypt' module enabled)
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*
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* You may also supply a custom bytes generator as an optional second
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* parameter.
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*
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* @param \Aws\Api\Service $service
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* @param callable|null $bytesGenerator
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*
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* @return callable
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*/
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public static function wrap(
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Service $service,
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callable $bytesGenerator = null
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) {
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return function (callable $handler) use ($service, $bytesGenerator) {
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return new self($handler, $service, $bytesGenerator);
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};
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}
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public function __construct(
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callable $nextHandler,
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Service $service,
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callable $bytesGenerator = null
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) {
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$this->bytesGenerator = $bytesGenerator
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?: $this->findCompatibleRandomSource();
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$this->service = $service;
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$this->nextHandler = $nextHandler;
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}
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public function __invoke(
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CommandInterface $command,
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RequestInterface $request = null
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) {
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$handler = $this->nextHandler;
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if ($this->bytesGenerator) {
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$operation = $this->service->getOperation($command->getName());
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$members = $operation->getInput()->getMembers();
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foreach ($members as $member => $value) {
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if ($value['idempotencyToken']) {
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$bytes = call_user_func($this->bytesGenerator, 16);
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// populating UUIDv4 only when the parameter is not set
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$command[$member] = $command[$member]
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?: $this->getUuidV4($bytes);
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// only one member could have the trait enabled
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break;
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}
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}
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}
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return $handler($command, $request);
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}
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/**
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* This function generates a random UUID v4 string,
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* which is used as auto filled token value.
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*
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* @param string $bytes 16 bytes of pseudo-random bytes
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* @return string
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* More information about UUID v4, see:
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* https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_.28random.29
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* https://tools.ietf.org/html/rfc4122#page-14
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*/
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private static function getUuidV4($bytes)
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{
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// set version to 0100
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$bytes[6] = chr(ord($bytes[6]) & 0x0f | 0x40);
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// set bits 6-7 to 10
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$bytes[8] = chr(ord($bytes[8]) & 0x3f | 0x80);
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return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($bytes), 4));
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}
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/**
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* This function decides the PHP function used in generating random bytes.
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*
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* @return callable|null
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*/
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private function findCompatibleRandomSource()
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{
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if (function_exists('random_bytes')) {
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return 'random_bytes';
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}
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if (function_exists('openssl_random_pseudo_bytes')) {
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return 'openssl_random_pseudo_bytes';
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}
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if (function_exists('mcrypt_create_iv')) {
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return 'mcrypt_create_iv';
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}
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}
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}
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