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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 | |||
| 7 | daniel-mar | 24 | private static function tryDownloadPhpSha3() { |
| 25 | // Download file if required (usually composer should do it) |
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| 26 | if (file_exists(__DIR__.'/Sha3.php')) include_once __DIR__.'/Sha3.php'; |
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| 27 | if (!class_exists('\bb\Sha3\Sha3')) { |
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| 28 | $sha3_lib = file_get_contents('https://raw.githubusercontent.com/danielmarschall/php-sha3/master/src/Sha3.php'); |
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| 29 | if (@file_put_contents(__DIR__.'/Sha3.php', $sha3_lib)) { |
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| 30 | include_once __DIR__.'/Sha3.php'; |
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| 31 | } else { |
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| 32 | eval('?>'.$sha3_lib); |
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| 6 | daniel-mar | 33 | } |
| 7 | daniel-mar | 34 | } |
| 2 | daniel-mar | 35 | } |
| 36 | |||
| 7 | daniel-mar | 37 | private static function sha3_512($message, $raw_output=false) { |
| 38 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
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| 39 | return hash('sha3-512', $message, $raw_output); |
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| 40 | } else { |
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| 41 | self::tryDownloadPhpSha3(); |
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| 42 | return \bb\Sha3\Sha3::hash($message, 512, $raw_output); |
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| 43 | } |
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| 44 | } |
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| 45 | |||
| 4 | daniel-mar | 46 | private static function sha3_512_hmac($message, $key, $raw_output=false) { |
| 47 | // RFC 2104 HMAC |
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| 7 | daniel-mar | 48 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
| 49 | return hash_hmac('sha3-512', $message, $key, $raw_output); |
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| 50 | } else { |
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| 51 | self::tryDownloadPhpSha3(); |
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| 52 | return \bb\Sha3\Sha3::hash_hmac($message, $key, 512, $raw_output); |
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| 53 | } |
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| 4 | daniel-mar | 54 | } |
| 55 | |||
| 10 | daniel-mar | 56 | private static function getOpenTransFileName($ip_target, $random, $server_secret) { |
| 8 | daniel-mar | 57 | $dir = defined('VTS_CS_OPEN_TRANS_DIR') ? VTS_CS_OPEN_TRANS_DIR : __DIR__.'/cache'; |
| 58 | if ($dir == '') $dir = '.'; /** @phpstan-ignore-line */ |
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| 59 | |||
| 60 | // First, delete challenges which were never completed |
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| 9 | daniel-mar | 61 | $files = glob($dir.'/vts_client_challenge_*.tmp'); |
| 6 | daniel-mar | 62 | $expire = strtotime('-3 DAYS'); |
| 63 | foreach ($files as $file) { |
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| 64 | if (!is_file($file)) continue; |
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| 65 | if (filemtime($file) > $expire) continue; |
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| 66 | @unlink($file); |
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| 67 | } |
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| 4 | daniel-mar | 68 | |
| 10 | daniel-mar | 69 | return $dir.'/vts_client_challenge_'.self::sha3_512_hmac($ip_target.'/'.$random, $server_secret).'.tmp'; |
| 6 | daniel-mar | 70 | } |
| 4 | daniel-mar | 71 | |
| 6 | daniel-mar | 72 | public static function checkValidation($client_response, $max_time=10, $server_secret) { |
| 73 | list($starttime, $ip_target, $challenge, $answer, $challenge_integrity) = $client_response; |
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| 10 | daniel-mar | 74 | $open_trans_file = self::getOpenTransFileName($ip_target, $answer, $server_secret); |
| 4 | daniel-mar | 75 | |
| 2 | daniel-mar | 76 | if ($ip_target != $_SERVER['REMOTE_ADDR']) { |
| 4 | daniel-mar | 77 | throw new \Exception('Wrong IP'); |
| 2 | daniel-mar | 78 | } else if (time()-$starttime > $max_time) { |
| 4 | daniel-mar | 79 | throw new \Exception('Challenge expired'); |
| 80 | } else if ($challenge_integrity != self::sha3_512_hmac($challenge,$server_secret)) { |
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| 81 | throw new \Exception('Challenge integrity failed'); |
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| 2 | daniel-mar | 82 | } else if ($challenge !== self::sha3_512($starttime.'/'.$ip_target.'/'.$answer)) { |
| 4 | daniel-mar | 83 | throw new \Exception('Wrong answer'); |
| 6 | daniel-mar | 84 | } else if (!file_exists($open_trans_file)) { |
| 85 | throw new \Exception('Challenge submitted twice or transaction missing'); |
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| 2 | daniel-mar | 86 | } else { |
| 9 | daniel-mar | 87 | @unlink($open_trans_file); |
| 2 | daniel-mar | 88 | return true; |
| 89 | } |
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| 90 | } |
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| 91 | |||
| 6 | daniel-mar | 92 | public static function createChallenge($complexity=50000, $server_secret) { |
| 93 | $offset = 0; // doesn't matter |
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| 94 | $min = $offset; |
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| 95 | $max = $offset + $complexity; |
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| 2 | daniel-mar | 96 | |
| 97 | $starttime = time(); |
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| 98 | |||
| 99 | $random = rand($min,$max); // TODO: cryptographic rand |
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| 100 | |||
| 101 | $ip_target = $_SERVER['REMOTE_ADDR']; |
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| 102 | |||
| 103 | $challenge = self::sha3_512($starttime.'/'.$ip_target.'/'.$random); |
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| 104 | |||
| 4 | daniel-mar | 105 | $challenge_integrity = self::sha3_512_hmac($challenge,$server_secret); |
| 2 | daniel-mar | 106 | |
| 4 | daniel-mar | 107 | $send_to_client = array($starttime, $ip_target, $challenge, $min, $max, $challenge_integrity); |
| 108 | |||
| 10 | daniel-mar | 109 | $open_trans_file = self::getOpenTransFileName($ip_target, $random, $server_secret); |
| 6 | daniel-mar | 110 | if (@file_put_contents($open_trans_file, '') === false) { |
| 111 | throw new \Exception("Cannot write $open_trans_file"); |
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| 112 | } |
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| 2 | daniel-mar | 113 | |
| 6 | daniel-mar | 114 | return $send_to_client; |
| 2 | daniel-mar | 115 | } |
| 116 | |||
| 117 | } |