[Mailer] [Smtp] Add DSN option to make SocketStream bind to IPv4

Author: quilius

src/Symfony/Component/Mailer/CHANGELOG.md

@@ -6,6 +6,7 @@ CHANGELOG
 
  * Add DSN param `retry_period` to override default email transport retry period
  * Add `Dsn::getBooleanOption()`
+ * Add DSN param `source_ip` to allow binding to a (specific) IPv4 or IPv6 address.
 
 7.2
 ---

src/Symfony/Component/Mailer/Tests/Transport/Smtp/EsmtpTransportFactoryTest.php

@@ -180,6 +180,20 @@ public static function createProvider(): iterable
             Dsn::fromString('smtp://:@example.com:465?auto_tls=false'),
             $transport,
         ];
+
+        $transport = new EsmtpTransport('example.com', 465, true, null, $logger);
+        $transport->getStream()->setSourceIp('0.0.0.0');
+        yield [
+            Dsn::fromString('smtps://:@example.com:465?source_ip=0.0.0.0'),
+            $transport,
+        ];
+
+        $transport = new EsmtpTransport('example.com', 465, true, null, $logger);
+        $transport->getStream()->setSourceIp('[2606:4700:20::681a:5fb]');
+        yield [
+            Dsn::fromString('smtps://:@example.com:465?source_ip=[2606:4700:20::681a:5fb]'),
+            $transport,
+        ];
     }
 
     public static function unsupportedSchemeProvider(): iterable

src/Symfony/Component/Mailer/Transport/Smtp/EsmtpTransportFactory.php

@@ -38,6 +38,9 @@ public function create(Dsn $dsn): TransportInterface
 
         /** @var SocketStream $stream */
         $stream = $transport->getStream();
+        if ('' !== $sourceIp = $dsn->getOption('source_ip', '')) {
+            $stream->setSourceIp($sourceIp);
+        }
         $streamOptions = $stream->getStreamOptions();
 
         if ('' !== $dsn->getOption('verify_peer') && !filter_var($dsn->getOption('verify_peer', true), \FILTER_VALIDATE_BOOL)) {