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| Rev | Author | Line No. | Line |
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| 2 | daniel-mar | 1 | <?php |
| 2 | |||
| 3 | /* |
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| 4 | * php_clientchallenge |
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| 6 | daniel-mar | 5 | * Copyright 2021-2022 Daniel Marschall, ViaThinkSoft |
| 2 | daniel-mar | 6 | * |
| 7 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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| 8 | * you may not use this file except in compliance with the License. |
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| 9 | * You may obtain a copy of the License at |
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| 10 | * |
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| 11 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 12 | * |
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| 13 | * Unless required by applicable law or agreed to in writing, software |
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| 14 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 15 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 16 | * See the License for the specific language governing permissions and |
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| 17 | * limitations under the License. |
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| 18 | */ |
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| 19 | |||
| 20 | namespace ViaThinkSoft\RateLimitingChallenge; |
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| 21 | |||
| 22 | class ClientChallenge { |
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| 23 | |||
| 6 | daniel-mar | 24 | const OPEN_TRANS_DIR = __DIR__.'/cache'; |
| 25 | |||
| 7 | daniel-mar | 26 | private static function tryDownloadPhpSha3() { |
| 27 | // Download file if required (usually composer should do it) |
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| 28 | if (file_exists(__DIR__.'/Sha3.php')) include_once __DIR__.'/Sha3.php'; |
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| 29 | if (!class_exists('\bb\Sha3\Sha3')) { |
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| 30 | $sha3_lib = file_get_contents('https://raw.githubusercontent.com/danielmarschall/php-sha3/master/src/Sha3.php'); |
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| 31 | if (@file_put_contents(__DIR__.'/Sha3.php', $sha3_lib)) { |
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| 32 | include_once __DIR__.'/Sha3.php'; |
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| 33 | } else { |
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| 34 | eval('?>'.$sha3_lib); |
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| 6 | daniel-mar | 35 | } |
| 7 | daniel-mar | 36 | } |
| 2 | daniel-mar | 37 | } |
| 38 | |||
| 7 | daniel-mar | 39 | private static function sha3_512($message, $raw_output=false) { |
| 40 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
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| 41 | return hash('sha3-512', $message, $raw_output); |
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| 42 | } else { |
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| 43 | self::tryDownloadPhpSha3(); |
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| 44 | return \bb\Sha3\Sha3::hash($message, 512, $raw_output); |
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| 45 | } |
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| 46 | } |
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| 47 | |||
| 4 | daniel-mar | 48 | private static function sha3_512_hmac($message, $key, $raw_output=false) { |
| 49 | // RFC 2104 HMAC |
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| 7 | daniel-mar | 50 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
| 51 | return hash_hmac('sha3-512', $message, $key, $raw_output); |
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| 52 | } else { |
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| 53 | self::tryDownloadPhpSha3(); |
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| 54 | return \bb\Sha3\Sha3::hash_hmac($message, $key, 512, $raw_output); |
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| 55 | } |
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| 4 | daniel-mar | 56 | } |
| 57 | |||
| 6 | daniel-mar | 58 | private static function getOpenTransFileName($ip_target, $random) { |
| 59 | // Delete challenges which were never completed |
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| 60 | $files = glob(self::OPEN_TRANS_DIR.'/*.tmp'); |
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| 61 | $expire = strtotime('-3 DAYS'); |
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| 62 | foreach ($files as $file) { |
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| 63 | if (!is_file($file)) continue; |
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| 64 | if (filemtime($file) > $expire) continue; |
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| 65 | @unlink($file); |
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| 66 | } |
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| 4 | daniel-mar | 67 | |
| 6 | daniel-mar | 68 | return self::OPEN_TRANS_DIR.'/'.self::sha3_512($ip_target.'/'.$random).'.tmp'; |
| 69 | } |
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| 4 | daniel-mar | 70 | |
| 6 | daniel-mar | 71 | public static function checkValidation($client_response, $max_time=10, $server_secret) { |
| 72 | list($starttime, $ip_target, $challenge, $answer, $challenge_integrity) = $client_response; |
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| 73 | $open_trans_file = self::getOpenTransFileName($ip_target, $answer); |
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| 4 | daniel-mar | 74 | |
| 2 | daniel-mar | 75 | if ($ip_target != $_SERVER['REMOTE_ADDR']) { |
| 4 | daniel-mar | 76 | throw new \Exception('Wrong IP'); |
| 2 | daniel-mar | 77 | } else if (time()-$starttime > $max_time) { |
| 4 | daniel-mar | 78 | throw new \Exception('Challenge expired'); |
| 79 | } else if ($challenge_integrity != self::sha3_512_hmac($challenge,$server_secret)) { |
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| 80 | throw new \Exception('Challenge integrity failed'); |
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| 2 | daniel-mar | 81 | } else if ($challenge !== self::sha3_512($starttime.'/'.$ip_target.'/'.$answer)) { |
| 4 | daniel-mar | 82 | throw new \Exception('Wrong answer'); |
| 6 | daniel-mar | 83 | } else if (!file_exists($open_trans_file)) { |
| 84 | throw new \Exception('Challenge submitted twice or transaction missing'); |
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| 2 | daniel-mar | 85 | } else { |
| 6 | daniel-mar | 86 | unlink($open_trans_file); |
| 2 | daniel-mar | 87 | return true; |
| 88 | } |
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| 89 | } |
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| 90 | |||
| 6 | daniel-mar | 91 | public static function createChallenge($complexity=50000, $server_secret) { |
| 92 | $offset = 0; // doesn't matter |
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| 93 | $min = $offset; |
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| 94 | $max = $offset + $complexity; |
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| 2 | daniel-mar | 95 | |
| 96 | $starttime = time(); |
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| 97 | |||
| 98 | $random = rand($min,$max); // TODO: cryptographic rand |
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| 99 | |||
| 100 | $ip_target = $_SERVER['REMOTE_ADDR']; |
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| 101 | |||
| 102 | $challenge = self::sha3_512($starttime.'/'.$ip_target.'/'.$random); |
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| 103 | |||
| 4 | daniel-mar | 104 | $challenge_integrity = self::sha3_512_hmac($challenge,$server_secret); |
| 2 | daniel-mar | 105 | |
| 4 | daniel-mar | 106 | $send_to_client = array($starttime, $ip_target, $challenge, $min, $max, $challenge_integrity); |
| 107 | |||
| 6 | daniel-mar | 108 | $open_trans_file = self::getOpenTransFileName($ip_target, $random); |
| 109 | if (@file_put_contents($open_trans_file, '') === false) { |
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| 110 | throw new \Exception("Cannot write $open_trans_file"); |
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| 111 | } |
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| 2 | daniel-mar | 112 | |
| 6 | daniel-mar | 113 | return $send_to_client; |
| 2 | daniel-mar | 114 | } |
| 115 | |||
| 116 | } |