DD-WRT nvram dump

nvram-dump.php

<?php
  class nvram {
    public static function dump (string $nvramfile) {
      $nvram = file_get_contents($nvramfile);

      $header = unpack('a6header/v1record_count', $nvram);
      if ($header['header'] !== 'DD-WRT') {
        die('nvram format is not compatible);
      }
      $record_count = $header['record_count'];

      $nvram = substr($nvram, 8);
      $records = [];
      while (strlen($nvram) and count($records) < $record_count) {
        $name_size = ord($nvram[0]);
        $record_name = substr($nvram, 1, $name_size);
        $record_size = current(unpack('v', $nvram, $name_size + 1));
        $records[$record_name] = substr($nvram, $name_size + 3, $record_size);

        $nvram = substr($nvram, $name_size + $record_size + 3);
      }
      return $records;
    }
  }