Subversion Repositories php_clientchallenge

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  1. <?php
  2.  
  3. /*
  4.  * php_clientchallenge
  5.  * Copyright 2021-2022 Daniel Marschall, ViaThinkSoft
  6.  *
  7.  * Licensed under the Apache License, Version 2.0 (the "License");
  8.  * you may not use this file except in compliance with the License.
  9.  * You may obtain a copy of the License at
  10.  *
  11.  *     http://www.apache.org/licenses/LICENSE-2.0
  12.  *
  13.  * Unless required by applicable law or agreed to in writing, software
  14.  * distributed under the License is distributed on an "AS IS" BASIS,
  15.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16.  * See the License for the specific language governing permissions and
  17.  * limitations under the License.
  18.  */
  19.  
  20. namespace ViaThinkSoft\RateLimitingChallenge;
  21.  
  22. class ClientChallenge {
  23.  
  24.         private static function tryDownloadPhpSha3() {
  25.                 // Download file if required (usually composer should do it)
  26.                 if (file_exists(__DIR__.'/Sha3.php')) include_once __DIR__.'/Sha3.php';
  27.                 if (!class_exists('\bb\Sha3\Sha3')) {
  28.                         $sha3_lib = file_get_contents('https://raw.githubusercontent.com/danielmarschall/php-sha3/master/src/Sha3.php');
  29.                         if (@file_put_contents(__DIR__.'/Sha3.php', $sha3_lib)) {
  30.                                 include_once __DIR__.'/Sha3.php';
  31.                         } else {
  32.                                 eval('?>'.$sha3_lib);
  33.                         }
  34.                 }
  35.         }
  36.  
  37.         private static function sha3_512($message, $raw_output=false) {
  38.                 if (version_compare(PHP_VERSION, '7.1.0') >= 0) {
  39.                         return hash('sha3-512', $message, $raw_output);
  40.                 } else {
  41.                         self::tryDownloadPhpSha3();
  42.                         return \bb\Sha3\Sha3::hash($message, 512, $raw_output);
  43.                 }
  44.         }
  45.  
  46.         private static function sha3_512_hmac($message, $key, $raw_output=false) {
  47.                 // RFC 2104 HMAC
  48.                 if (version_compare(PHP_VERSION, '7.1.0') >= 0) {
  49.                         return hash_hmac('sha3-512', $message, $key, $raw_output);
  50.                 } else {
  51.                         self::tryDownloadPhpSha3();
  52.                         return \bb\Sha3\Sha3::hash_hmac($message, $key, 512, $raw_output);
  53.                 }
  54.         }
  55.  
  56.         private static function getOpenTransFileName($ip_target, $random, $server_secret) {
  57.                 $dir = defined('VTS_CS_OPEN_TRANS_DIR') ? VTS_CS_OPEN_TRANS_DIR : __DIR__.'/cache';
  58.                 if ($dir == '') $dir = '.'; /** @phpstan-ignore-line */
  59.  
  60.                 // First, delete challenges which were never completed
  61.                 $files = glob($dir.'/vts_client_challenge_*.tmp');
  62.                 $expire = strtotime('-3 DAYS');
  63.                 foreach ($files as $file) {
  64.                         if (!is_file($file)) continue;
  65.                         if (filemtime($file) > $expire) continue;
  66.                         @unlink($file);
  67.                 }
  68.  
  69.                 return $dir.'/vts_client_challenge_'.self::sha3_512_hmac($ip_target.'/'.$random, $server_secret).'.tmp';
  70.         }
  71.  
  72.         public static function checkValidation($client_response, $max_time=10, $server_secret) {
  73.                 if (!is_array($client_response)) throw new \Exception('Challenge response is invalid');
  74.                 if (count($client_response) != 5) throw new \Exception('Challenge response is invalid');
  75.                 list($starttime, $ip_target, $challenge, $answer, $challenge_integrity) = $client_response;
  76.                 if (!is_numeric($starttime)) throw new \Exception('Challenge response is invalid');
  77.                 if (!is_string($ip_target)) throw new \Exception('Challenge response is invalid');
  78.                 if (!is_string($challenge)) throw new \Exception('Challenge response is invalid');
  79.                 if (!is_numeric($answer)) throw new \Exception('Challenge response is invalid');
  80.                 if (!is_string($challenge_integrity)) throw new \Exception('Challenge response is invalid');
  81.  
  82.                 $open_trans_file = self::getOpenTransFileName($ip_target, $answer, $server_secret);
  83.  
  84.                 $current_ip = (isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : 'unknown');
  85.                 if ($ip_target != $current_ip) {
  86.                         throw new \Exception("IP address has changed. Please try again. (current IP $current_ip, expected $ip_target)");
  87.                 } else if (time()-$starttime > $max_time) {
  88.                         throw new \Exception('Challenge expired. Please try again.');
  89.                 } else if ($challenge_integrity != self::sha3_512_hmac($challenge,$server_secret)) {
  90.                         throw new \Exception('Challenge integrity failed');
  91.                 } else if ($challenge !== self::sha3_512($starttime.'/'.$ip_target.'/'.$answer)) {
  92.                         throw new \Exception('Wrong answer');
  93.                 } else if (!file_exists($open_trans_file)) {
  94.                         throw new \Exception('Challenge submitted twice or transaction missing');
  95.                 } else {
  96.                         @unlink($open_trans_file);
  97.                         return true;
  98.                 }
  99.         }
  100.  
  101.         public static function createChallenge($complexity=50000, $server_secret) {
  102.                 $offset = 0; // doesn't matter
  103.                 $min = $offset;
  104.                 $max = $offset + $complexity;
  105.  
  106.                 $starttime = time();
  107.  
  108.                 $random = rand($min,$max); // TODO: cryptographic rand
  109.  
  110.                 $ip_target = $_SERVER['REMOTE_ADDR'];
  111.  
  112.                 $challenge = self::sha3_512($starttime.'/'.$ip_target.'/'.$random);
  113.  
  114.                 $challenge_integrity = self::sha3_512_hmac($challenge,$server_secret);
  115.  
  116.                 $send_to_client = array($starttime, $ip_target, $challenge, $min, $max, $challenge_integrity);
  117.  
  118.                 $open_trans_file = self::getOpenTransFileName($ip_target, $random, $server_secret);
  119.                 if (@file_put_contents($open_trans_file, '') === false) {
  120.                         throw new \Exception("Cannot write $open_trans_file");
  121.                 }
  122.  
  123.                 return $send_to_client;
  124.         }
  125.  
  126. }
  127.