Subversion Repositories oidplus

<?php

/*

 * OIDplus 2.0

 * Copyright 2019 - 2022 Daniel Marschall, ViaThinkSoft

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

namespace ViaThinkSoft\OIDplus;

class OIDplusCaptchaPluginVtsClientChallenge extends OIDplusCaptchaPlugin {

        public static function id(): string {

                return 'ViaThinkSoft Client Challenge';

        }

        public function isVisible(): bool {

                return false;

        }

        public function csrfUnlock($actionID) {

                if ($actionID == 'get_challenge') {

                        return true;

                }

                return false;

        }

        public function action($actionID, $params) {

                if ($actionID == 'get_challenge') {

                        $server_secret='VtsClientChallenge:'.OIDplus::baseConfig()->getValue('SERVER_SECRET');

                        $offset = 0; // doesn't matter

                        $min = $offset;

                        $max = $offset + OIDplus::baseConfig()->getValue('VTS_CAPTCHA_COMPLEXITY', 50000);

                        if ($max > mt_getrandmax()) $max = mt_getrandmax();

                        $starttime = time();

                        $random = mt_rand($min,$max);

                        $ip_target = isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : 'unknown';

                        $challenge = sha3_512($starttime.'/'.$ip_target.'/'.$random);

                        $challenge_integrity = sha3_512_hmac($challenge,$server_secret);

                        $send_to_client = array($starttime, $ip_target, $challenge, $min, $max, $challenge_integrity);

                        $open_trans_file = self::getOpenTransFileName($ip_target, $random);

                        if (@file_put_contents($open_trans_file, '') === false) {

                                throw new OIDplusException(_L('Cannot write file %1', $open_trans_file));

                        }

                        return array(

                                "status" => 0,

                                "challenge" => $send_to_client,

                                // Autosolve on=calculate result on page load; off=calculate result on form submit

                                "autosolve" => OIDplus::baseConfig()->getValue('VTS_CAPTCHA_AUTOSOLVE', true)

                        );

                }

        }

        private static function getOpenTransFileName($ip_target, $random) {

                $dir = OIDplus::localpath().'/userdata/cache';

                $server_secret='VtsClientChallenge:'.OIDplus::baseConfig()->getValue('SERVER_SECRET');

                // First, delete challenges which were never completed

                $files = glob($dir.'/vts_client_challenge_*.tmp');

                $expire = strtotime('-3 DAYS');

                foreach ($files as $file) {

                        if (!is_file($file)) continue;

                        if (filemtime($file) > $expire) continue;

                        @unlink($file);

                }

                return $dir.'/vts_client_challenge_'.sha3_512_hmac($ip_target.'/'.$random, $server_secret).'.tmp';

        }

        public function captchaGenerate($header_text=null, $footer_text=null) {

                return '<noscript>'.

                       '<p><font color="red">'._L('You need to enable JavaScript to solve the CAPTCHA.').'</font></p>'.

                       '</noscript>'.

                       '<input type="hidden" id="vts_validation_result" name="vts_validation_result" value="">'.

                       '<script>'.

                       'OIDplusCaptchaPluginVtsClientChallenge.captchaShow('.js_escape(OIDplus::webpath(null,OIDplus::PATH_RELATIVE)).');'.

                       '</script>';

        }

        public function captchaVerify($params, $fieldname=null) {

                if (is_null($fieldname)) $fieldname = 'vts_validation_result';

                $server_secret='VtsClientChallenge:'.OIDplus::baseConfig()->getValue('SERVER_SECRET');

                if (!isset($params[$fieldname])) throw new OIDplusException(_L('No challenge response found').' (A)');

                $client_response = @json_decode($params[$fieldname], true);

                if (!is_array($client_response)) throw new OIDplusException(_L('Challenge response is invalid').' (B)');

                if (count($client_response) != 5) throw new OIDplusException(_L('Challenge response is invalid').' (C)');

                list($starttime, $ip_target, $challenge, $answer, $challenge_integrity) = $client_response;

                if (!is_numeric($starttime)) throw new OIDplusException(_L('Challenge response is invalid').' (D)');

                if (!is_string($ip_target)) throw new OIDplusException(_L('Challenge response is invalid').' (E)');

                if (!is_string($challenge)) throw new OIDplusException(_L('Challenge response is invalid').' (F)');

                if (!is_numeric($answer)) throw new OIDplusException(_L('Challenge response is invalid').' (G)');

                if (!is_string($challenge_integrity)) throw new OIDplusException(_L('Challenge response is invalid').' (H)');

                $open_trans_file = self::getOpenTransFileName($ip_target, $answer);

                $current_ip = (isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : 'unknown');

                if ($ip_target != $current_ip) {

                        throw new OIDplusException(_L('IP address has changed. Please try again. (current IP %1, expected %2)', $current_ip, $ip_target));

                } else if (time()-$starttime > OIDplus::baseConfig()->getValue('VTS_CAPTCHA_MAXTIME', 10*60/*10 minutes*/)) {

                        throw new OIDplusException(_L('Challenge expired. Please try again.'));

                } else if ($challenge_integrity != sha3_512_hmac($challenge,$server_secret)) {

                        throw new OIDplusException(_L('Challenge integrity failed'));

                } else if ($challenge !== sha3_512($starttime.'/'.$ip_target.'/'.$answer)) {

                        throw new OIDplusException(_L('Wrong answer'));

                } else if (!file_exists($open_trans_file)) {

                        throw new OIDplusException(_L('Challenge submitted twice or transaction missing'));

                } else {

                        @unlink($open_trans_file);

                }

        }

        public static function setupHTML(): string {

                return '<div id="CAPTCHAPLUGIN_PARAMS_VtsClientChallenge">'.

                       '<p>'._L('ViaThinkSoft Client Challenge lets the client computer solve a cryptographic problem instead of letting the user solve a CAPTCHA. This slows down brute-force attacks.').'</p>'.

                       '</div>';

        }

}