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<?php |
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namespace A17\Twill\Services\Uploader; |
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use Illuminate\Config\Repository as Config; |
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class SignS3Upload |
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{ |
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private $bucket; |
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private $secret; |
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/** |
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* @var Config |
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*/ |
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protected $config; |
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/** |
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* @param Config $config |
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*/ |
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public function __construct(Config $config) |
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{ |
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$this->config = $config; |
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} |
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public function fromPolicy($policy, SignUploadListener $listener, $disk = 'libraries') |
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{ |
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$policyObject = json_decode($policy, true); |
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$policyJson = json_encode($policyObject); |
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$this->bucket = $this->config->get('filesystems.disks.' . $disk . '.bucket'); |
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$this->secret = $this->config->get('filesystems.disks.' . $disk . '.secret'); |
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$signedPolicy = $this->signPolicy($policyJson); |
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if ($signedPolicy) { |
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return $listener->uploadIsSigned($signedPolicy); |
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} |
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return $listener->uploadIsNotValid(); |
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} |
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private function signPolicy($policyJson) |
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{ |
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$policyObject = json_decode($policyJson, true); |
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if ($this->isValid($policyObject)) { |
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$encodedPolicy = base64_encode($policyJson); |
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$signedPolicy = array( |
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'policy' => $encodedPolicy, |
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'signature' => $this->signV4Policy($policyObject, $encodedPolicy), |
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); |
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return $signedPolicy; |
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} |
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return null; |
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} |
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private function isValid($policy) |
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{ |
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$expectedMaxSize = null; |
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$conditions = $policy["conditions"]; |
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$bucket = null; |
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$parsedMaxSize = null; |
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for ($i = 0; $i < count($conditions); ++$i) { |
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$condition = $conditions[$i]; |
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if (isset($condition["bucket"])) { |
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$bucket = $condition["bucket"]; |
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} else if (isset($condition[0]) && $condition[0] == "content-length-range") { |
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$parsedMaxSize = $condition[2]; |
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} |
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} |
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return $bucket == $this->bucket && $parsedMaxSize == (string) $expectedMaxSize; |
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} |
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private function signV4Policy($policy, $encodedPolicy) |
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{ |
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foreach ($policy["conditions"] as $condition) { |
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if (isset($condition["x-amz-credential"])) { |
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$credentialCondition = $condition["x-amz-credential"]; |
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} |
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} |
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$pattern = "/.+\/(.+)\\/(.+)\/s3\/aws4_request/"; |
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preg_match($pattern, $credentialCondition, $matches); |
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$dateKey = hash_hmac('sha256', $matches[1], 'AWS4' . $this->secret, true); |
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$dateRegionKey = hash_hmac('sha256', $matches[2], $dateKey, true); |
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$dateRegionServiceKey = hash_hmac('sha256', 's3', $dateRegionKey, true); |
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$signingKey = hash_hmac('sha256', 'aws4_request', $dateRegionServiceKey, true); |
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return hash_hmac('sha256', $encodedPolicy, $signingKey); |
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} |
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} |
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If the size of the collection does not change during the iteration, it is generally a good practice to compute it beforehand, and not on each iteration: