MDL-48501 recaptchalib_v2: add new lib to support reCAPTCHA v2

lang/en/auth.php

@@ -103,6 +103,7 @@
 $string['getanaudiocaptcha'] = 'Get an audio CAPTCHA';
 $string['getanimagecaptcha'] = 'Get an image CAPTCHA';
 $string['getanothercaptcha'] = 'Get another CAPTCHA';
+$string['getrecaptchaapi'] = 'To use reCAPTCHA you must get an API key from <a href=\'https://www.google.com/recaptcha/admin\'>https://www.google.com/recaptcha/admin</a>';
 $string['guestloginbutton'] = 'Guest login button';
 $string['changepassword'] = 'Change password URL';
 $string['changepasswordhelp'] = 'URL of lost password recovery page, which will be sent to users in an email. Note that this setting will have no effect if a forgotten password URL is set in the authentication common settings.';

lib/recaptchalib_v2.php

@@ -0,0 +1,189 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+ // This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * This is a PHP library that handles calling reCAPTCHA v2.
+ *
+ *    - Documentation
+ *          {@link https://developers.google.com/recaptcha/docs/display}
+ *    - Get a reCAPTCHA API Key
+ *          {@link https://www.google.com/recaptcha/admin}
+ *    - Discussion group
+ *          {@link http://groups.google.com/group/recaptcha}
+ *
+ * @package core
+ * @copyright 2018 Jeff Webster
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The reCAPTCHA URL's
+ */
+define('RECAPTCHA_API_URL', 'https://www.google.com/recaptcha/api.js');
+define('RECAPTCHA_VERIFY_URL', 'https://www.google.com/recaptcha/api/siteverify');
+
+/**
+ * Returns the language code the reCAPTCHA element should use.
+ * Google reCAPTCHA uses different language codes than Moodle so we must convert.
+ * https://developers.google.com/recaptcha/docs/language
+ *
+ * @return string A language code
+ */
+function recaptcha_lang() {
+
+    $mlang = current_language();
+
+    $glang = $mlang;
+    switch ($glang) {
+        case 'en':
+            $glang = 'en-GB';
+            break;
+        case 'en_us':
+            $glang = 'en';
+            break;
+        case 'zh_cn':
+            $glang = 'zh-CN';
+            break;
+        case 'zh_tw':
+            $glang = 'zh-TW';
+            break;
+        case 'fr_ca':
+            $glang = 'fr-CA';
+            break;
+        case 'pt_br':
+            $glang = 'pt-BR';
+            break;
+        case 'he':
+            $glang = 'iw';
+            break;
+    }
+    // For any language code that didn't change reduce down to the base language.
+    if (($mlang === $glang) and (strpos($mlang, '_') !== false)) {
+        list($glang, $trash) = explode('_', $mlang, 2);
+    }
+    return $glang;
+}
+
+/**
+ * Gets the challenge HTML
+ * This is called from the browser, and the resulting reCAPTCHA HTML widget
+ * is embedded within the HTML form it was called from.
+ *
+ * @param string $apiurl URL for reCAPTCHA API
+ * @param string $pubkey The public key for reCAPTCHA
+ * @return string - The HTML to be embedded in the user's form.
+ */
+function recaptcha_get_challenge_html($apiurl, $pubkey) {
+    global $CFG, $PAGE;
+
+    // To use reCAPTCHA you must have an API key.
+    if ($pubkey === null || $pubkey === '') {
+        return get_string('getrecaptchaapi', 'auth');
+    }
+
+    $jscode = "
+        var recaptchacallback = function() {
+            grecaptcha.render('recaptcha_element', {
+              'sitekey' : '$pubkey'
+            });
+        }";
+
+    $lang = recaptcha_lang();
+    $apicode = "\n<script type=\"text/javascript\" ";
+    $apicode .= "src=\"$apiurl?onload=recaptchacallback&render=explicit&hl=$lang\" async defer>";
+    $apicode .= "</script>\n";
+
+    $return = html_writer::script($jscode, '');
+    $return .= html_writer::div('', 'recaptcha_element', array('id' => 'recaptcha_element'));
+    $return .= $apicode;
+
+    return $return;
+}
+
+/**
+ * Calls an HTTP POST function to verify if the user's response was correct
+ *
+ * @param string $verifyurl URL for reCAPTCHA verification
+ * @param string $privkey The private key for reCAPTCHA
+ * @param string $remoteip The user's IP
+ * @param string $response The response from reCAPTCHA
+ * @return ReCaptchaResponse
+ */
+function recaptcha_check_response($verifyurl, $privkey, $remoteip, $response) {
+    global $CFG;
+    require_once($CFG->libdir.'/filelib.php');
+
+    // Check response - isvalid boolean, error string.
+    $checkresponse = array('isvalid' => false, 'error' => 'check-not-started');
+
+    // To use reCAPTCHA you must have an API key.
+    if ($privkey === null || $privkey === '') {
+        $checkresponse['isvalid'] = false;
+        $checkresponse['error'] = 'no-apikey';
+        return $checkresponse;
+    }
+
+    // For security reasons, you must pass the remote ip to reCAPTCHA.
+    if ($remoteip === null || $remoteip === '') {
+        $checkresponse['isvalid'] = false;
+        $checkresponse['error'] = 'no-remoteip';
+        return $checkresponse;
+    }
+
+    // Discard spam submissions.
+    if ($response === null || strlen($response) === 0) {
+        $checkresponse['isvalid'] = false;
+        $checkresponse['error'] = 'incorrect-captcha-sol';
+        return $checkresponse;
+    }
+
+    $params = array('secret' => $privkey, 'remoteip' => $remoteip, 'response' => $response);
+    $curl = new curl();
+    $curlresponse = $curl->post($verifyurl, $params);
+
+    if ($curl->get_errno() === 0) {
+        $curldata = json_decode($curlresponse);
+
+        if (isset($curldata->success) && $curldata->success === true) {
+            $checkresponse['isvalid'] = true;
+            $checkresponse['error'] = '';
+        } else {
+            $checkresponse['isvalid'] = false;
+            $checkresponse['error'] = $curldata->{error-codes};
+        }
+    } else {
+        $checkresponse['isvalid'] = false;
+        $checkresponse['error'] = 'check-failed';
+    }
+    return $checkresponse;
+}
+

lib/upgrade.txt

@@ -15,6 +15,7 @@ information provided here is intended especially for developers.
   - notify()
 * XMLDB now validates the PATH attribute on every install.xml file. Both the XMLDB editor and installation will fail
   when a problem is detected with it. Please ensure your plugins contain correct directory relative paths.
+* Add recaptchalib_v2.php for support of reCAPTCHA v2.
 
 === 3.4 ===