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<?php
/**
* Copyright 2017 Facebook, Inc.
*
* You are hereby granted a non-exclusive, worldwide, royalty-free license to
* use, copy, modify, and distribute this software in source code or binary
* form for use in connection with the web services and APIs provided by
* Facebook.
*
* As with any software that integrates with the Facebook platform, your use
* of this software is subject to the Facebook Developer Principles and
* Policies [http://developers.facebook.com/policy/]. This copyright notice
* shall be included in all copies or substantial portions of the software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
*/
namespace Facebook\PseudoRandomString;
use Facebook\Exceptions\FacebookSDKException;
use InvalidArgumentException;
class PseudoRandomStringGeneratorFactory
{
private function __construct()
{
// a factory constructor should never be invoked
}
/**
* Pseudo random string generator creation.
*
* @param PseudoRandomStringGeneratorInterface|string|null $generator
*
* @throws InvalidArgumentException If the pseudo random string generator must be set to "random_bytes", "mcrypt", "openssl", or "urandom", or be an instance of Facebook\PseudoRandomString\PseudoRandomStringGeneratorInterface.
*
* @return PseudoRandomStringGeneratorInterface
*/
public static function createPseudoRandomStringGenerator($generator)
{
if (!$generator) {
return self::detectDefaultPseudoRandomStringGenerator();
}
if ($generator instanceof PseudoRandomStringGeneratorInterface) {
return $generator;
}
if ('random_bytes' === $generator) {
return new RandomBytesPseudoRandomStringGenerator();
}
if ('mcrypt' === $generator) {
return new McryptPseudoRandomStringGenerator();
}
if ('openssl' === $generator) {
return new OpenSslPseudoRandomStringGenerator();
}
if ('urandom' === $generator) {
return new UrandomPseudoRandomStringGenerator();
}
throw new InvalidArgumentException('The pseudo random string generator must be set to "random_bytes", "mcrypt", "openssl", or "urandom", or be an instance of Facebook\PseudoRandomString\PseudoRandomStringGeneratorInterface');
}
/**
* Detects which pseudo-random string generator to use.
*
* @throws FacebookSDKException If unable to detect a cryptographically secure pseudo-random string generator.
*
* @return PseudoRandomStringGeneratorInterface
*/
private static function detectDefaultPseudoRandomStringGenerator()
{
// Check for PHP 7's CSPRNG first to keep mcrypt deprecation messages from appearing in PHP 7.1.
if (function_exists('random_bytes')) {
return new RandomBytesPseudoRandomStringGenerator();
}
// Since openssl_random_pseudo_bytes() can sometimes return non-cryptographically
// secure pseudo-random strings (in rare cases), we check for mcrypt_create_iv() next.
if (function_exists('mcrypt_create_iv')) {
return new McryptPseudoRandomStringGenerator();
}
if (function_exists('openssl_random_pseudo_bytes')) {
return new OpenSslPseudoRandomStringGenerator();
}
if (!ini_get('open_basedir') && is_readable('/dev/urandom')) {
return new UrandomPseudoRandomStringGenerator();
}
throw new FacebookSDKException('Unable to detect a cryptographically secure pseudo-random string generator.');
}
}
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