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Generate Expiring Amazon S3 Link with Custom File Name
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$client = array( | |
'key' => '<key>', | |
'secret' => '<secret>' | |
); | |
$expires = 5; // In minutes | |
// output signed URL string | |
echo el_s3_getTemporaryLink($client['key'], $client['secret'], 'bucket', '<path:file-MD5>', '<filename>', $expires); | |
/** | |
* Calculate the HMAC SHA1 hash of a string. | |
* | |
* @param string $key The key to hash against | |
* @param string $data The data to hash | |
* @param int $blocksize Optional blocksize | |
* @return string HMAC SHA1 | |
*/ | |
function el_crypto_hmacSHA1($key, $data, $blocksize = 64) { | |
if (strlen($key) > $blocksize) $key = pack('H*', sha1($key)); | |
$key = str_pad($key, $blocksize, chr(0x00)); | |
$ipad = str_repeat(chr(0x36), $blocksize); | |
$opad = str_repeat(chr(0x5c), $blocksize); | |
$hmac = pack( 'H*', sha1( | |
($key ^ $opad) . pack( 'H*', sha1( | |
($key ^ $ipad) . $data | |
)) | |
)); | |
return base64_encode($hmac); | |
} | |
/** | |
* Create temporary URLs to your protected Amazon S3 files. | |
* | |
* @param string $accessKey Your Amazon S3 access key | |
* @param string $secretKey Your Amazon S3 secret key | |
* @param string $bucket The bucket (bucket.s3.amazonaws.com) | |
* @param string $path The target file path | |
* @param int $expires In minutes | |
* @return string Temporary Amazon S3 URL | |
* @see http://awsdocs.s3.amazonaws.com/S3/20060301/s3-dg-20060301.pdf | |
*/ | |
function el_s3_getTemporaryLink($accessKey, $secretKey, $bucket, $path, $filename = '', $expires = 5) { | |
// Calculate expiry time | |
$expires = time() + intval(floatval($expires) * 60); | |
// Fix the path; encode and sanitize | |
$path = str_replace('%2F', '/', rawurlencode($path = ltrim($path, '/'))); | |
if($filename) { | |
$path .= '?response-content-disposition=attachment; filename="'. $filename. '"'; | |
} | |
// Path for signature starts with the bucket | |
$signpath = '/'. $bucket .'/'. $path; | |
// S3 friendly string to sign | |
$signsz = implode("\n", array('GET', null, null, $expires, $signpath)); | |
// Calculate the hash | |
$signature = el_crypto_hmacSHA1($secretKey, $signsz); | |
// Glue the URL ... | |
$url = sprintf('http://%s.s3.amazonaws.com/%s', $bucket, $path); | |
// ... to the query string ... | |
$qs = http_build_query(array( | |
'AWSAccessKeyId' => $accessKey, | |
'Expires' => $expires, | |
'Signature' => $signature, | |
)); | |
// ... and return the URL! | |
return ($filename) ? $url.'&'.$qs : $url.'?'.$qs ; | |
} |
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