Symfony\Component\HttpFoundation\Request::setTrustedHosts PHP Method

    public static function setTrustedHosts(array $hostPatterns)
    {
        self::$trustedHostPatterns = array_map(function ($hostPattern) {
            return sprintf('#%s#i', $hostPattern);
        }, $hostPatterns);
        // we need to reset trusted hosts on trusted host patterns change
        self::$trustedHosts = array();
    }

 public function testTrustedHosts()
 {
     // create a request
     $request = Request::create('/');
     // no trusted host set -> no host check
     $request->headers->set('host', 'evil.com');
     $this->assertEquals('evil.com', $request->getHost());
     // add a trusted domain and all its subdomains
     Request::setTrustedHosts(array('^([a-z]{9}\\.)?trusted\\.com$'));
     // untrusted host
     $request->headers->set('host', 'evil.com');
     try {
         $request->getHost();
         $this->fail('Request::getHost() should throw an exception when host is not trusted.');
     } catch (\UnexpectedValueException $e) {
         $this->assertEquals('Untrusted Host "evil.com"', $e->getMessage());
     }
     // trusted hosts
     $request->headers->set('host', 'trusted.com');
     $this->assertEquals('trusted.com', $request->getHost());
     $this->assertEquals(80, $request->getPort());
     $request->server->set('HTTPS', true);
     $request->headers->set('host', 'trusted.com');
     $this->assertEquals('trusted.com', $request->getHost());
     $this->assertEquals(443, $request->getPort());
     $request->server->set('HTTPS', false);
     $request->headers->set('host', 'trusted.com:8000');
     $this->assertEquals('trusted.com', $request->getHost());
     $this->assertEquals(8000, $request->getPort());
     $request->headers->set('host', 'subdomain.trusted.com');
     $this->assertEquals('subdomain.trusted.com', $request->getHost());
     // reset request for following tests
     Request::setTrustedHosts(array());
 }