lib/recaptchalib_v2.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  // This file is part of Moodle - http://moodle.org/
  17 //
  18 // Moodle is free software: you can redistribute it and/or modify
  19 // it under the terms of the GNU General Public License as published by
  20 // the Free Software Foundation, either version 3 of the License, or
  21 // (at your option) any later version.
  22 //
  23 // Moodle is distributed in the hope that it will be useful,
  24 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  25 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26 // GNU General Public License for more details.
  27 //
  28 // You should have received a copy of the GNU General Public License
  29 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  30
  31 /**
  32  * This is a PHP library that handles calling reCAPTCHA v2.
  33  *
  34  *    - Documentation
  35  *          {@link https://developers.google.com/recaptcha/docs/display}
  36  *    - Get a reCAPTCHA API Key
  37  *          {@link https://www.google.com/recaptcha/admin}
  38  *    - Discussion group
  39  *          {@link http://groups.google.com/group/recaptcha}
  40  *
  41  * @package core
  42  * @copyright 2018 Jeff Webster
  43  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  44  */
  45
  46 defined('MOODLE_INTERNAL') || die();
  47
  48 /**
  49  * The reCAPTCHA URL's
  50  */
  51 define('RECAPTCHA_API_URL', 'https://www.google.com/recaptcha/api.js');
  52 define('RECAPTCHA_VERIFY_URL', 'https://www.google.com/recaptcha/api/siteverify');
  53
  54 /**
  55  * Returns the language code the reCAPTCHA element should use.
  56  * Google reCAPTCHA uses different language codes than Moodle so we must convert.
  57  * https://developers.google.com/recaptcha/docs/language
  58  *
  59  * @param string $lang Language to use. If not provided, get current language.
  60  * @return string A language code
  61  */
  62 function recaptcha_lang($lang = null) {
  63
  64     if (empty($lang)) {
  65         $lang = current_language();
  66     }
  67
  68     $glang = $lang;
  69     switch ($glang) {
  70         case 'en':
  71             $glang = 'en-GB';
  72             break;
  73         case 'en_us':
  74             $glang = 'en';
  75             break;
  76         case 'zh_cn':
  77             $glang = 'zh-CN';
  78             break;
  79         case 'zh_tw':
  80             $glang = 'zh-TW';
  81             break;
  82         case 'fr_ca':
  83             $glang = 'fr-CA';
  84             break;
  85         case 'pt_br':
  86             $glang = 'pt-BR';
  87             break;
  88         case 'he':
  89             $glang = 'iw';
  90             break;
  91     }
  92     // For any language code that didn't change reduce down to the base language.
  93     if (($lang === $glang) and (strpos($lang, '_') !== false)) {
  94         list($glang, $trash) = explode('_', $lang, 2);
  95     }
  96     return $glang;
  97 }
  98
  99 /**
 100  * Gets the challenge HTML
 101  * This is called from the browser, and the resulting reCAPTCHA HTML widget
 102  * is embedded within the HTML form it was called from.
 103  *
 104  * @param string $apiurl URL for reCAPTCHA API
 105  * @param string $pubkey The public key for reCAPTCHA
 106  * @param string $lang Language to use. If not provided, get current language.
 107  * @return string - The HTML to be embedded in the user's form.
 108  */
 109 function recaptcha_get_challenge_html($apiurl, $pubkey, $lang = null) {
 110     global $CFG, $PAGE;
 111
 112     // To use reCAPTCHA you must have an API key.
 113     if ($pubkey === null || $pubkey === '') {
 114         return get_string('getrecaptchaapi', 'auth');
 115     }
 116
 117     $jscode = "
 118         var recaptchacallback = function() {
 119             grecaptcha.render('recaptcha_element', {
 120               'sitekey' : '$pubkey'
 121             });
 122         }";
 123
 124     $lang = recaptcha_lang($lang);
 125     $apicode = "\n<script type=\"text/javascript\" ";
 126     $apicode .= "src=\"$apiurl?onload=recaptchacallback&render=explicit&hl=$lang\" async defer>";
 127     $apicode .= "</script>\n";
 128
 129     $return = html_writer::script($jscode, '');
 130     $return .= html_writer::div('', 'recaptcha_element', array('id' => 'recaptcha_element'));
 131     $return .= $apicode;
 132
 133     return $return;
 134 }
 135
 136 /**
 137  * Calls an HTTP POST function to verify if the user's response was correct
 138  *
 139  * @param string $verifyurl URL for reCAPTCHA verification
 140  * @param string $privkey The private key for reCAPTCHA
 141  * @param string $remoteip The user's IP
 142  * @param string $response The response from reCAPTCHA
 143  * @return ReCaptchaResponse
 144  */
 145 function recaptcha_check_response($verifyurl, $privkey, $remoteip, $response) {
 146     global $CFG;
 147     require_once($CFG->libdir.'/filelib.php');
 148
 149     // Check response - isvalid boolean, error string.
 150     $checkresponse = array('isvalid' => false, 'error' => 'check-not-started');
 151
 152     // To use reCAPTCHA you must have an API key.
 153     if ($privkey === null || $privkey === '') {
 154         $checkresponse['isvalid'] = false;
 155         $checkresponse['error'] = 'no-apikey';
 156         return $checkresponse;
 157     }
 158
 159     // For security reasons, you must pass the remote ip to reCAPTCHA.
 160     if ($remoteip === null || $remoteip === '') {
 161         $checkresponse['isvalid'] = false;
 162         $checkresponse['error'] = 'no-remoteip';
 163         return $checkresponse;
 164     }
 165
 166     // Discard spam submissions.
 167     if ($response === null || strlen($response) === 0) {
 168         $checkresponse['isvalid'] = false;
 169         $checkresponse['error'] = 'incorrect-captcha-sol';
 170         return $checkresponse;
 171     }
 172
 173     $params = array('secret' => $privkey, 'remoteip' => $remoteip, 'response' => $response);
 174     $curl = new curl();
 175     $curlresponse = $curl->post($verifyurl, $params);
 176
 177     if ($curl->get_errno() === 0) {
 178         $curldata = json_decode($curlresponse);
 179
 180         if (isset($curldata->success) && $curldata->success === true) {
 181             $checkresponse['isvalid'] = true;
 182             $checkresponse['error'] = '';
 183         } else {
 184             $checkresponse['isvalid'] = false;
 185             $checkresponse['error'] = $curldata->{error-codes};
 186         }
 187     } else {
 188         $checkresponse['isvalid'] = false;
 189         $checkresponse['error'] = 'check-failed';
 190     }
 191     return $checkresponse;
 192 }
 193