PrivateBin/lib/Persistence/TrafficLimiter.php

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<?php
/**
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* PrivateBin
*
* a zero-knowledge paste bin
*
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* @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
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* @version 1.3.5
*/
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namespace PrivateBin\Persistence;
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use IPLib\Factory;
use PrivateBin\Configuration;
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/**
* 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;
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/**
* listed IPs are exempted from limits, defaults to null
*
* @access private
* @static
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* @var string|null
*/
private static $_exempted = 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 $exempted
*/
public static function setExempted($exempted)
{
self::$_exempted = $exempted;
}
/**
* 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::setExempted($conf->getKey('exempted', 'traffic'));
if (($option = $conf->getKey('header', 'traffic')) !== '') {
$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());
}
/**
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* 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)
{
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if (is_string($ipRange)) {
$ipRange = trim($ipRange);
}
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$address = Factory::addressFromString($_SERVER[self::$_ipKey]);
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$range = Factory::rangeFromString($ipRange);
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// address could not be parsed, we might not be in IP space and try a string comparison instead
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if (is_null($address)) {
return $_SERVER[self::$_ipKey] === $ipRange;
}
// range could not be parsed, possibly an invalid ip range given in config
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if (is_null($range)) {
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return false;
}
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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 $_ipKey is exempted from ratelimiting
if (!empty(self::$_exempted)) {
$exIp_array = explode(',', self::$_exempted);
foreach ($exIp_array as $ipRange) {
if (self::matchIp($ipRange) === true) {
return true;
}
}
}
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// this hash is used as an array key, hence a shorter algo is used
$hash = self::getHash('sha256');
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$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();
$result = true;
}
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if (!self::$_store->setValue((string) $tl, 'traffic_limiter', $hash)) {
error_log('failed to store the traffic limiter, it probably contains outdated information');
}
return $result;
}
}