/tool dns-update

<?php
  require_once('Net/DNS2.php');

function do_update($user, $ip, &$error) {
  if($user->type == 'server') {
    $u = new Net_DNS2_Updater($user->zone, array('nameservers' => array($user->server)));
    try {
      $u->deleteAny($user->host, 'A');
      $a = Net_DNS2_RR::fromString($user->host.' '.$user->ttl.' IN A '.$ip);
      $u->add($a);
      $u->signTSIG($user->key_name, $user->key_value);
      $u->update();
      return true;
    } catch(Net_DNS2_Exception $e) {
      $error = $e->getMessage();
      return false;
    }
  } elseif($user->type == 'url') {
    $url = $user->url.$ip;
    $ch = curl_init($url);
    curl_setopt_array($ch, array(
      CURLOPT_CONNECTTIMEOUT => 10,
      CURLOPT_TIMEOUT => 10,
      CURLOPT_HEADER => false,
      CURLOPT_RETURNTRANSFER => true,
      CURLOPT_FAILONERROR => true
    ));
    $data = curl_exec($ch);
    $err = curl_errno($ch);
    curl_close($ch);
    if($err != 0) {
      $error = 'curl error '.$err;
      return false;
    } else {
      //FIXME: check $data for some string?
      return true;
    }
  } else {
    $error = 'unknown type';
    return false;
  }
}

  if(!isset($_GET['user']) || !isset($_GET['pass'])) die('missing parameter(s)');
  $ip = $_SERVER['REMOTE_ADDR'];
  $data = json_decode(file_get_contents('data.json'));
  foreach($data->users as $user) {
    if($user->user == $_GET['user'] && $user->pass == $_GET['pass']) {
      if($user->ip != $ip) {
        if(do_update($user, $ip, $err)) {
          $user->ip = $ip;
          file_put_contents('data.json', json_encode($data));
          die('updated');
        } else {
          die('update error: '.$err);
        }
      }
      die('no update needed');
    }
  }
  die('login error');
?>

{"users":[{
  "user":"user1",
  "pass":"pass",
  "ip":"",
  "type":"server",
  "zone":"example.net",
  "host":"dyndnshost.example.net",
  "server":"192.0.2.1",
  "ttl":60,
  "key_name":"tsigkey",
  "key_value":"supersecretkey"
},{
  "user":"user2",
  "pass":"pass",
  "ip":"",
  "type":"url",
  "url":"http:\/\/dyndns.example.com\/update?user=xxx&pass=xxx&ip="
}]}