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.         const OPEN_TRANS_DIR = __DIR__.'/cache';
  25.  
  26.         private static function tryDownloadPhpSha3() {
  27.                 // Download file if required (usually composer should do it)
  28.                 if (file_exists(__DIR__.'/Sha3.php')) include_once __DIR__.'/Sha3.php';
  29.                 if (!class_exists('\bb\Sha3\Sha3')) {
  30.                         $sha3_lib = file_get_contents('https://raw.githubusercontent.com/danielmarschall/php-sha3/master/src/Sha3.php');
  31.                         if (@file_put_contents(__DIR__.'/Sha3.php', $sha3_lib)) {
  32.                                 include_once __DIR__.'/Sha3.php';
  33.                         } else {
  34.                                 eval('?>'.$sha3_lib);
  35.                         }
  36.                 }
  37.         }
  38.  
  39.         private static function sha3_512($message, $raw_output=false) {
  40.                 if (version_compare(PHP_VERSION, '7.1.0') >= 0) {
  41.                         return hash('sha3-512', $message, $raw_output);
  42.                 } else {
  43.                         self::tryDownloadPhpSha3();
  44.                         return \bb\Sha3\Sha3::hash($message, 512, $raw_output);
  45.                 }
  46.         }
  47.  
  48.         private static function sha3_512_hmac($message, $key, $raw_output=false) {
  49.                 // RFC 2104 HMAC
  50.                 if (version_compare(PHP_VERSION, '7.1.0') >= 0) {
  51.                         return hash_hmac('sha3-512', $message, $key, $raw_output);
  52.                 } else {
  53.                         self::tryDownloadPhpSha3();
  54.                         return \bb\Sha3\Sha3::hash_hmac($message, $key, 512, $raw_output);
  55.                 }
  56.         }
  57.  
  58.         private static function getOpenTransFileName($ip_target, $random) {
  59.                 // Delete challenges which were never completed
  60.                 $files = glob(self::OPEN_TRANS_DIR.'/*.tmp');
  61.                 $expire = strtotime('-3 DAYS');
  62.                 foreach ($files as $file) {
  63.                         if (!is_file($file)) continue;
  64.                         if (filemtime($file) > $expire) continue;
  65.                         @unlink($file);
  66.                 }
  67.  
  68.                 return self::OPEN_TRANS_DIR.'/'.self::sha3_512($ip_target.'/'.$random).'.tmp';
  69.         }
  70.  
  71.         public static function checkValidation($client_response, $max_time=10, $server_secret) {
  72.                 list($starttime, $ip_target, $challenge, $answer, $challenge_integrity) = $client_response;
  73.                 $open_trans_file = self::getOpenTransFileName($ip_target, $answer);
  74.  
  75.                 if ($ip_target != $_SERVER['REMOTE_ADDR']) {
  76.                         throw new \Exception('Wrong IP');
  77.                 } else if (time()-$starttime > $max_time) {
  78.                         throw new \Exception('Challenge expired');
  79.                 } else if ($challenge_integrity != self::sha3_512_hmac($challenge,$server_secret)) {
  80.                         throw new \Exception('Challenge integrity failed');
  81.                 } else if ($challenge !== self::sha3_512($starttime.'/'.$ip_target.'/'.$answer)) {
  82.                         throw new \Exception('Wrong answer');
  83.                 } else if (!file_exists($open_trans_file)) {
  84.                         throw new \Exception('Challenge submitted twice or transaction missing');
  85.                 } else {
  86.                         unlink($open_trans_file);
  87.                         return true;
  88.                 }
  89.         }
  90.  
  91.         public static function createChallenge($complexity=50000, $server_secret) {
  92.                 $offset = 0; // doesn't matter
  93.                 $min = $offset;
  94.                 $max = $offset + $complexity;
  95.  
  96.                 $starttime = time();
  97.  
  98.                 $random = rand($min,$max); // TODO: cryptographic rand
  99.  
  100.                 $ip_target = $_SERVER['REMOTE_ADDR'];
  101.  
  102.                 $challenge = self::sha3_512($starttime.'/'.$ip_target.'/'.$random);
  103.  
  104.                 $challenge_integrity = self::sha3_512_hmac($challenge,$server_secret);
  105.  
  106.                 $send_to_client = array($starttime, $ip_target, $challenge, $min, $max, $challenge_integrity);
  107.  
  108.                 $open_trans_file = self::getOpenTransFileName($ip_target, $random);
  109.                 if (@file_put_contents($open_trans_file, '') === false) {
  110.                         throw new \Exception("Cannot write $open_trans_file");
  111.                 }
  112.  
  113.                 return $send_to_client;
  114.         }
  115.  
  116. }
  117.