同一个ip在一小时内不能提交多次

Question

我正在尝试创建一个网络调查问卷,但我不希望同一个人使用相同的IP在一小时内提交不止一次,我使用PHP,我认为我需要 $_SERVER['REMOTE_ADDR']用来获取客户端IP和存储在会话或数据库中,然后使用它来比较新的IP,我不知道它是否正确,不知道如何在PHP中精确实现这一点,任何人都可以帮助我,提前感谢!

Answer 1

提交调查时:

 /*
   Tracking table structure:
    `id`              INT(11) unsigned NOT NULL AUTO_INCREMENT
    `client_ip`       VARCHAR(15) NOT NULL
    `submitted_time`  DATETIME NOT NULL
 */

 $query = "SELECT count(`id`) AS 'count'
           FROM `tracking_table`
           WHERE 
             `client_ip` = '".mysqli_real_escape_string($link, $_SERVER['REMOTE_ADDR'])."'
             AND `submitted_time` > '".date('Y-m-d H:i:s',strtotime('-1 hour'))."'
           LIMIT 1";
 $result = mysqli_fetch_assoc(mysqli_query($link, $query));

 if ($result['count'] > 0) {
   echo "You have already submitted within the last hour";
   exit;
 }

 // process survey here

 $query = "INSERT INTO `tracking_table`
             (`client_ip`, `submitted_time`)
           VALUES
             ('".mysqli_real_escape_string($link, $_SERVER['REMOTE_ADDR'])."', ".date('Y-m-d H:i:s').")";
 mysqli_query($link, $query);

但是,您可能会发现这不是一个好的要求 - 有许多有效的情况,多个用户可能使用相同的IP地址(例如,学生住宿).您可能通过强加此限制来阻止有效提交.

编辑

以下是如何使用cookie执行此操作的基本概述(考虑到下面讨论的限制).

我们的cookie系统适用于一对值.ckv_1将保留上次调查提交的时间戳.ckv_2将持有基于时间戳和盐的哈希值,以阻止人们搞砸cookie.显然,如果两个cookie都被删除,我们将无法检测到它,但至少这提供了某种验证:

function get_cookie_hash ($timestamp, $salt) {
  return md5("Extra random static string; TS: $timestamp; Salt: $salt; Extra random static string.");
}

$cookieSalt = 'Th1si54rAnd0MsTr1nG!';

// If at least one of the cookies was returned, validate the request
if (!empty($_COOKIE['ckv_1']) || !empty($_COOKIE['ckv_2'])) {

  $valid = FALSE;

  do { // Wrapped in a do-while to allow us to break out easily
    // Make sure both value are set
    if (empty($_COOKIE['ckv_1']) || empty($_COOKIE['ckv_2'])) break;
    // Get old timestamp as integer
    $oldTS = hexdec($_COOKIE['ckv_1']);
    // Make sure timestamp is more than one hour old, and the hash cookie matches it
    if ($oldTS > (time() - 3600) || $_COOKIE['ckv_2'] != get_cookie_hash($oldTS, $cookieSalt)) break;
    // OK if you get here
    $valid = TRUE;
  } while (FALSE);

  if (!$valid) {
    echo "Sorry - you cannot submit a survey more than once in an hour.";
    exit;
  }

}

// process survey here

// Set the tracking cookies after processing (but before any output!)
// We'll set them as HTTP only to help prevent XSS-type attacks
$cookieTime = time();
setcookie('ckv_1', dechex($cookieTime), 7200, '', '', FALSE, TRUE);
setcookie('ckv_2', get_cookie_hash($cookieTime, $cookieSalt), 7200, '', '', FALSE, TRUE);