PrivateBin/lib/Persistence/TrafficLimiter.php
2021-06-16 05:32:45 +02:00

181 lines
4.6 KiB
PHP

<?php
/**
* PrivateBin
*
* a zero-knowledge paste bin
*
* @link https://github.com/PrivateBin/PrivateBin
* @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
* @license https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
* @version 1.3.5
*/
namespace PrivateBin\Persistence;
use IPLib\Factory;
use PrivateBin\Configuration;
/**
* TrafficLimiter
*
* Handles traffic limiting, so no user does more than one call per 10 seconds.
*/
class TrafficLimiter extends AbstractPersistence
{
/**
* time limit in seconds, defaults to 10s
*
* @access private
* @static
* @var int
*/
private static $_limit = 10;
/**
* listed ips are exempted from limits, defaults to null
*
* @access private
* @static
* @var string|null
*/
private static $_exemptedIp = null;
/**
* key to fetch IP address
*
* @access private
* @static
* @var string
*/
private static $_ipKey = 'REMOTE_ADDR';
/**
* set the time limit in seconds
*
* @access public
* @static
* @param int $limit
*/
public static function setLimit($limit)
{
self::$_limit = $limit;
}
/**
* set a list of ip(ranges) as string
*
* @access public
* @static
* @param string $exemptedIps
*/
public static function setExemptedIp($exemptedIp)
{
self::$_exemptedIp = $exemptedIp;
}
/**
* set configuration options of the traffic limiter
*
* @access public
* @static
* @param Configuration $conf
*/
public static function setConfiguration(Configuration $conf)
{
self::setLimit($conf->getKey('limit', 'traffic'));
self::setExemptedIp($conf->getKey('exemptedIp', 'traffic'));
if (($option = $conf->getKey('header', 'traffic')) !== null) {
$httpHeader = 'HTTP_' . $option;
if (array_key_exists($httpHeader, $_SERVER) && !empty($_SERVER[$httpHeader])) {
self::$_ipKey = $httpHeader;
}
}
}
/**
* get a HMAC of the current visitors IP address
*
* @access public
* @static
* @param string $algo
* @return string
*/
public static function getHash($algo = 'sha512')
{
return hash_hmac($algo, $_SERVER[self::$_ipKey], ServerSalt::get());
}
/**
* Validate $_ipKey against configured ipranges. If matched we will ignore the ip
*
* @access private
* @static
* @param string $ipRange
* @return bool
*/
private static function matchIp($ipRange = null)
{
if (is_string($ipRange)) {
$ipRange = trim($ipRange);
}
$address = Factory::addressFromString($_SERVER[self::$_ipKey]);
$range = Factory::rangeFromString($ipRange);
// address could not be parsed, we might not be in IP space and try a string comparison instead
if (is_null($address)) {
return $_SERVER[self::$_ipKey] === $ipRange;
}
// range could not be parsed, possibly an invalid ip range given in config
if (is_null($range)) {
return false;
}
return $address->matches($range);
}
/**
* traffic limiter
*
* Make sure the IP address makes at most 1 request every 10 seconds.
*
* @access public
* @static
* @return bool
*/
public static function canPass()
{
// disable limits if set to less then 1
if (self::$_limit < 1) {
return true;
}
// Check if $_ipKey is exempted from ratelimiting
if (!is_null(self::$_exemptedIp)) {
$exIp_array = explode(',', self::$_exemptedIp);
foreach ($exIp_array as $ipRange) {
if (self::matchIp($ipRange) === true) {
return true;
}
}
}
// this hash is used as an array key, hence a shorter algo is used
$hash = self::getHash('sha256');
$now = time();
$tl = (int) self::$_store->getValue('traffic_limiter', $hash);
self::$_store->purgeValues('traffic_limiter', $now - self::$_limit);
if ($tl > 0 && ($tl + self::$_limit >= $now)) {
$result = false;
} else {
$tl = time();
$result = true;
}
if (!self::$_store->setValue((string) $tl, 'traffic_limiter', $hash)) {
error_log('failed to store the traffic limiter, it probably contains outdated information');
}
return $result;
}
}