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   1  <?php
   2  /**
   3   * This file is part of the ramsey/uuid library
   4   *
   5   * For the full copyright and license information, please view the LICENSE
   6   * file that was distributed with this source code.
   7   *
   8   * @copyright Copyright (c) Ben Ramsey <[email protected]>
   9   * @license http://opensource.org/licenses/MIT MIT
  10   * @link https://benramsey.com/projects/ramsey-uuid/ Documentation
  11   * @link https://packagist.org/packages/ramsey/uuid Packagist
  12   * @link https://github.com/ramsey/uuid GitHub
  13   */
  14  
  15  namespace Ramsey\Uuid\Provider\Node;
  16  
  17  use Exception;
  18  use Ramsey\Uuid\Provider\NodeProviderInterface;
  19  
  20  /**
  21   * RandomNodeProvider provides functionality to generate a random node ID, in
  22   * the event that the node ID could not be obtained from the host system
  23   *
  24   * @link http://tools.ietf.org/html/rfc4122#section-4.5
  25   */
  26  class RandomNodeProvider implements NodeProviderInterface
  27  {
  28      /**
  29       * Returns the system node ID
  30       *
  31       * @return string System node ID as a hexadecimal string
  32       * @throws Exception if it was not possible to gather sufficient entropy
  33       */
  34      public function getNode()
  35      {
  36          $nodeBytes = random_bytes(6);
  37  
  38          // Split the node bytes for math on 32-bit systems.
  39          $nodeMsb = substr($nodeBytes, 0, 3);
  40          $nodeLsb = substr($nodeBytes, 3);
  41  
  42          // Set the multicast bit; see RFC 4122, section 4.5.
  43          $nodeMsb = hex2bin(
  44              str_pad(
  45                  dechex(hexdec(bin2hex($nodeMsb)) | 0x010000),
  46                  6,
  47                  '0',
  48                  STR_PAD_LEFT
  49              )
  50          );
  51  
  52          // Recombine the node bytes.
  53          $node = $nodeMsb . $nodeLsb;
  54  
  55          return str_pad(bin2hex($node), 12, '0', STR_PAD_LEFT);
  56      }
  57  }