MDL-61921 admin: Support XOAUTH2 for outgoing mail

lib/phpmailer/moodle_phpmailer.php

@@ -54,6 +54,10 @@ class moodle_phpmailer extends \PHPMailer\PHPMailer\PHPMailer {
 
         if (!empty($CFG->smtpauthtype)) {
             $this->AuthType = $CFG->smtpauthtype;
+
+            if ($this->AuthType == 'XOAUTH2') {
+                $this->process_oauth();
+            }
         }
 
         // Some MTAs may do double conversion of LF if CRLF used, CRLF is required line ending in RFC 822bis.
@@ -65,7 +69,7 @@ class moodle_phpmailer extends \PHPMailer\PHPMailer\PHPMailer {
     }
 
     /**
-     * Extended AddCustomHeader function in order to stop duplicate 
+     * Extended AddCustomHeader function in order to stop duplicate
      * message-ids
      * http://tracker.moodle.org/browse/MDL-3681
      */
@@ -83,7 +87,7 @@ class moodle_phpmailer extends \PHPMailer\PHPMailer\PHPMailer {
 
     /**
      * Use internal moodles own core_text to encode mimeheaders.
-     * Fall back to phpmailers inbuilt functions if not 
+     * Fall back to phpmailers inbuilt functions if not
      */
     public function encodeHeader($str, $position = 'text') {
         $encoded = core_text::encode_mimeheader($str, $this->CharSet);
@@ -142,4 +146,32 @@ class moodle_phpmailer extends \PHPMailer\PHPMailer\PHPMailer {
             return parent::postSend();
         }
     }
+
+    /**
+     * Config the PHPMailer to use OAUTH if necessary.
+     */
+    private function process_oauth(): void {
+        global $CFG;
+
+        require_once($CFG->libdir . '/phpmailer/moodle_phpmailer_oauth.php');
+        if (!empty($CFG->smtpoauthservice)) {
+            // Get the issuer.
+            $issuer = \core\oauth2\api::get_issuer($CFG->smtpoauthservice);
+            // Validate the issuer and check if it is enabled or not.
+            if ($issuer && $issuer->get('enabled')) {
+                // Get the OAuth Client.
+                if ($oauthclient = \core\oauth2\api::get_system_oauth_client($issuer)) {
+                    $oauth = new moodle_phpmailer_oauth([
+                        'provider' => $oauthclient,
+                        'clientId' => $oauthclient->get_clientid(),
+                        'clientSecret' => $oauthclient->get_clientsecret(),
+                        'refreshToken' => $oauthclient->get_refresh_token(),
+                        'userName' => $CFG->smtpuser,
+                    ]);
+                    // Set the OAuth.
+                    $this->setOAuth($oauth);
+                }
+            }
+        }
+    }
 }

lib/phpmailer/moodle_phpmailer_oauth.php

@@ -0,0 +1,30 @@
+<?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/>.
+
+/**
+ * Moodle Customised version of the PHPMailer OAuth class
+ *
+ * @package    core
+ * @copyright  2022 Huong Nguyen <huongnv13@gmail.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class moodle_phpmailer_oauth extends \PHPMailer\PHPMailer\OAuth {
+
+    protected function getToken() {
+        return $this->provider->get_accesstoken()->token;
+    }
+
+}

lib/phpmailer/readme_moodle.txt

@@ -7,7 +7,7 @@ For more information on this version of PHPMailer, check out https://github.com/
 
 To upgrade this library:
 1. Download the latest release of PHPMailer in https://github.com/PHPMailer/PHPMailer/releases.
-2. Remove everything inside lib/phpmailer/ folder except README_MOODLE.txt and moodle_phpmailer.php.
+2. Remove everything inside lib/phpmailer/ folder except README_MOODLE.txt, moodle_phpmailer.php and moodle_phpmailer_oauth.php.
 3. Extract the contents of the release archive to lib/phpmailer.
 4. Remove the following files that were extracted:
    - composer.json