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

Author: quilius

src/Symfony/Component/Mailer/CHANGELOG.md

@@ -5,6 +5,7 @@ CHANGELOG
 ---
 
  * Add DSN param `retry_period` to override default email transport retry period
+ * Add DSN param `force_ipv4` to enforce binding to IPv4
 
 7.2
 ---

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

@@ -180,6 +180,26 @@ 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->forceIpv4();
+        yield [
+            Dsn::fromString('smtps://:@example.com:465?force_ipv4=true'),
+            $transport,
+        ];
+
+        $transport = new EsmtpTransport('example.com', 465, true, null, $logger);
+        $transport->forceIpv4();
+        yield [
+            Dsn::fromString('smtps://:@example.com:465?force_ipv4'),
+            $transport,
+        ];
+
+        $transport = new EsmtpTransport('example.com', 465, true, null, $logger);
+        yield [
+            Dsn::fromString('smtps://:@example.com:465?force_ipv4=false'),
+            $transport,
+        ];
     }
 
     public static function unsupportedSchemeProvider(): iterable

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

@@ -71,6 +71,14 @@ public function __construct(string $host = 'localhost', int $port = 0, ?bool $tl
         $stream->setPort($port);
     }
 
+    public function forceIpv4(): void
+    {
+        $stream = $this->getStream();
+        if ($stream instanceof SocketStream) {
+            $stream->setSourceIp('0.0.0.0');
+        }
+    }
+
     /**
      * @return $this
      */

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

@@ -32,9 +32,13 @@ public function create(Dsn $dsn): TransportInterface
         $tls = 'smtps' === $dsn->getScheme() ? true : ($autoTls ? null : false);
         $port = $dsn->getPort(0);
         $host = $dsn->getHost();
+        $forceIpv4 = '' === $dsn->getOption('force_ipv4') || filter_var($dsn->getOption('force_ipv4', false), \FILTER_VALIDATE_BOOL);
 
         $transport = new EsmtpTransport($host, $port, $tls, $this->dispatcher, $this->logger);
         $transport->setAutoTls($autoTls);
+        if ($forceIpv4) {
+            $transport->forceIpv4();
+        }
 
         /** @var SocketStream $stream */
         $stream = $transport->getStream();