<?PHP

$DYNDOMAIN = "home.domain.tld";
$DNSSERVER = "localhost";
$KEYFILE   = "/etc/bind/Khome.key.XXXXXXXX";
$TTL       = 60;
$DEBUG     = False;

$ACL = array(
  'admin' => '*',
  'bla'   => 'blub',
);

$ALLOWED_RECORDS = array(
  'A'     => True,
  'AAAA'  => True,
  'MX'    => True,
  'CNAME' => True,
  'NS'    => True,
  'TXT'   => True,
  'SPF'   => True,
  'SRV'   => True,
);

$user = $_SERVER['PHP_AUTH_USER'];

// validate and sanitize parameters
$value = filter_var($_REQUEST['value'], FILTER_SANITIZE_FULL_SPECIAL_CHARS, FILTER_FLAG_NO_ENCODE_QUOTES);
if(!strlen($value) > 0) $value = False;

if(isset($ALLOWED_RECORDS[$_REQUEST['type']])) {
  $type = $_REQUEST['type'];
  switch ($type) {
    case 'A':
              $value = filter_var($value, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4);
              break;
    case 'AAAA':
              $value = filter_var($value, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6);
              break;
    case 'SRV':
    case 'MX':
    case 'CNAME':
    case 'NS':
    case 'TXT':
    case 'SPF':
              break;
    default:
              $value = False;
              break;
  }
} else $type = False;

$domain = filter_var($_REQUEST['domain'], FILTER_SANITIZE_FULL_SPECIAL_CHARS, FILTER_FLAG_NO_ENCODE_QUOTES);
if(!strlen($domain) > 0) $domain = False;

// Check if we got all needed parameters and the user is allowed to change this sub
if($value !== False && $type !== False && $domain !== False && ( $ACL[$user] == '*' || $ACL[$user] == $domain )) {
  $nsupdateCommands = <<<EOT
server {$DNSSERVER}
update delete {$domain}.{$DYNDOMAIN}. {$type}
update add {$domain}.{$DYNDOMAIN}. {$TTL} {$type} {$value}
send
answer
quit
EOT;

  if($DEBUG === True) echo nl2br($nsupdateCommands);

  $descriptorspec = array(
    0 => array("pipe", "r"),  // STDIN 
  );

  if($DEBUG === True) {
    $descriptorspec[1] = array("pipe", "w"); // STDOUT
    $descriptorspec[2] = array("pipe", "w"); // STDERR
  };

  $cwd = '/tmp';

  $process = proc_open("/usr/bin/nsupdate -d -k $KEYFILE", $descriptorspec, $pipes, $cwd, NULL);
  if(is_resource($process)) {
    fwrite($pipes[0], $nsupdateCommands);
    fclose($pipes[0]);

    if($DEBUG === True) {
      echo nl2br(stream_get_contents($pipes[1]));
      fclose($pipes[1]);

      echo nl2br(stream_get_contents($pipes[2]));
      fclose($pipes[2]);
    }

    $return_value = proc_close($process);

    //echo "Rückgabewert des Kommandos: $return_value\n";
    echo $return_value;
    if($return_value == 0) {
      syslog(LOG_INFO, "Updated Record {$domain}.{$DYNDOMAIN} {$type} {$ip} ");
    } else {
      syslog(LOG_ERR, "Update Record {$domain}.{$DYNDOMAIN} {$type} {$ip} Failed");
    }
  }
} else {
  echo "Parameter Error.";
}
?>