feat: #3397418 Ensure origin headers of mails sent using the symfony-based...

<?php

declare(strict_types=1);

namespace Drupal\Core\Mailer\EventSubscriber;

use Drupal\Core\Config\ConfigFactoryInterface;

use Drupal\Core\Language\LanguageManagerInterface;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

use Symfony\Component\Mailer\Event\MessageEvent;

use Symfony\Component\Mime\Address;

use Symfony\Component\Mime\Email;

/**

 * Message subscriber which sets the from and sender headers.

 */

class OriginatorSubscriber implements EventSubscriberInterface {

  public function __construct(

    protected readonly ConfigFactoryInterface $configFactory,

    protected readonly LanguageManagerInterface $languageManager,

  ) {

  }

  /**

   * Sets the default from header and a sender header if necessary.

   *

   * @param \Symfony\Component\Mailer\Event\MessageEvent $event

   *   The message event.

   */

  public function onMessage(MessageEvent $event): void {

    $message = $event->getMessage();

    if ($message instanceof Email) {

      $this->setDefaultFrom($message);

      $this->setDefaultSender($message);

      $this->removeRedundantSender($message);

    }

  }

  /**

   * Sets the default from address.

   *

   * @param \Symfony\Component\Mime\Email $message

   *   The email message.

   */

  protected function setDefaultFrom(Email $message): void {

    $from = $message->getFrom();

    if (count($from) === 0) {

      $langcode = $message->getHeaders()->get('Content-Language')?->getBodyAsString();

      $siteAddress = $this->getSiteAddress($langcode);

      $message->from($siteAddress);

    }

  }

  /**

   * Sets the default sender address.

   *

   * @param \Symfony\Component\Mime\Email $message

   *   The email message.

   */

  protected function setDefaultSender(Email $message): void {

    if (!$message->getSender()) {

      $langcode = $message->getHeaders()->get('Content-Language')?->getBodyAsString();

      $siteAddress = $this->getSiteAddress($langcode);

      $message->sender($siteAddress);

    }

  }

  /**

   * Removes the Sender address if it is redundant.

   *

   * Rules according to RFC 5322 section 3.6.2 (Originator Fields):

   * * If the from field contains more than one mailbox specification in the

   *   mailbox-list, then the sender field, containing the field name

   *   "Sender" and a single mailbox specification, MUST appear in the

   *   message.

   * * The "Sender:" field specifies the mailbox of the agent responsible

   *   for the actual transmission of the message.

   * * If the originator of the message can be indicated by a single mailbox

   *   and the author and transmitter are identical, the "Sender:" field

   *   SHOULD NOT be used.

   *

   * @param \Symfony\Component\Mime\Email $message

   *   The email message.

   *

   * @see https://www.rfc-editor.org/rfc/rfc5322.html#section-3.6.2

   */

  protected function removeRedundantSender(Email $message): void {

    $from = $message->getFrom();

    $sender = $message->getSender();

    $senderRedundant = count($from) === 1 &&

      $sender !== NULL &&

      $from[0]->getAddress() === $sender->getAddress();

    if ($senderRedundant) {

      $message->getHeaders()->remove('Sender');

    }

  }

  /**

   * Returns the site email address.

   *

   * @param string|null $langcode

   *   The language code from the email.

   */

  protected function getSiteAddress(?string $langcode): Address {

    return $this->executeInEnvironment($langcode, function () {

      $config = $this->configFactory->get('system.site');

      return new Address($config->get('mail'), $config->get('name'));

    });

  }

  /**

   * Invokes the given callback after switching the config language.

   *

   * @param string|null $langcode

   *   The language code.

   * @param callable(): T $callback

   *   Callback to execute inside substituted environment.

   *

   * @return T

   *   Returns the result returned by the callback.

   *

   * @template T

   *

   * @todo Replace with execution environment once that is available.

   * @see: https://www.drupal.org/i/3536307

   */

  protected function executeInEnvironment(?string $langcode, callable $callback): mixed {

    $originalLanguage = $this->languageManager->getConfigOverrideLanguage();

    if ($langcode && ($language = $this->languageManager->getLanguage($langcode))) {

      $this->languageManager->setConfigOverrideLanguage($language);

    }

    try {

      return $callback();

    }

    finally {

      $this->languageManager->setConfigOverrideLanguage($originalLanguage);

    }

  }

  /**

   * {@inheritdoc}

   */

  public static function getSubscribedEvents(): array {

    return [

      // Should be the last one to allow header changes by other listeners.

      MessageEvent::class => ['onMessage', -255],

    ];

  }

}

  Symfony\Component\Mailer\Mailer:

    autowire: true

  Symfony\Component\Mailer\MailerInterface: '@Symfony\Component\Mailer\Mailer'

  Drupal\Core\Mailer\EventSubscriber\OriginatorSubscriber:

    autowire: true

name: 'Mailer event subscriber test'

type: module

description: 'Support module for mailer event subscriber testing.'

package: Testing

version: VERSION

services:

  mailer_event_subscriber_test.message_event_test_subscriber:

    class: Drupal\mailer_event_subscriber_test\EventSubscriber\MessageEventTestSubscriber

    arguments: ['@state']

    tags:

      - { name: 'event_subscriber' }

<?php

declare(strict_types=1);

namespace Drupal\mailer_event_subscriber_test\EventSubscriber;

use Drupal\Core\State\StateInterface;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

use Symfony\Component\Mailer\Event\MessageEvent;

use Symfony\Component\Mime\Address;

use Symfony\Component\Mime\Email;

/**

 * A message event test subscriber.

 */

class MessageEventTestSubscriber implements EventSubscriberInterface {

  /**

   * Constructs a new message event test subscriber.

   *

   * @param \Drupal\Core\State\StateInterface $state

   *   The state service.

   */

  public function __construct(

    protected StateInterface $state,

  ) {

  }

  /**

   * Sets a custom from header.

   *

   * @param \Symfony\Component\Mailer\Event\MessageEvent $event

   *   The message event.

   */

  public function setCustomFrom(MessageEvent $event): void {

    $customFrom = $this->state->get('mailer_event_subscriber_test.set_custom_from');

    $message = $event->getMessage();

    if (!empty($customFrom) && $message instanceof Email) {

      $message->from(Address::create($customFrom));

    }

  }

  /**

   * Sets a custom message sender header.

   *

   * @param \Symfony\Component\Mailer\Event\MessageEvent $event

   *   The message event.

   */

  public function setCustomMessageSender(MessageEvent $event): void {

    $customFrom = $this->state->get('mailer_event_subscriber_test.set_custom_message_sender');

    $message = $event->getMessage();

    if (!empty($customFrom) && $message instanceof Email) {

      $message->sender(Address::create($customFrom));

    }

  }

  /**

   * Sets a custom envelope sender.

   *

   * @param \Symfony\Component\Mailer\Event\MessageEvent $event

   *   The message event.

   */

  public function setCustomEnvelopeSender(MessageEvent $event): void {

    $customEnvelopeSender = $this->state->get('mailer_event_subscriber_test.set_custom_envelope_sender');

    if (!empty($customEnvelopeSender)) {

      $envelope = $event->getEnvelope();

      $envelope->setSender(Address::create($customEnvelopeSender));

    }

  }

  /**

   * {@inheritdoc}

   */

  public static function getSubscribedEvents(): array {

    return [

      MessageEvent::class => [

        ['setCustomFrom', 0],

        ['setCustomMessageSender', 0],

        ['setCustomEnvelopeSender', 0],

      ],

    ];

  }

}