Magento2 : Redirect Page From Observer

Question

I want to restrict some unwanted users to access the site. So I am redirecting them to 404 Page but my logic is going to an infinite loop as the event I am calling from controller_action_predispatch is called several times and I am not able to find the right one.

My Logic

namespace Namespace\Module\Observer;

class RedirectUsers implements \Magento\Framework\Event\ObserverInterface {

    protected $_myHelper;

    public function __construct(
        \Namespace\Module\Helper\Data $myHelper,
    ) {
        $this->_myHelper = $myHelper;
    }

    public function execute(\Magento\Framework\Event\Observer $observer) {
        if(in_array($currentUser, $restrictedUsers)){
            $url = $this->_myHelper->getNoRoutePageUrl();
            header('Location: ' . $url);
            exit;
        }
    }
}

My event.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="controller_action_predispatch">
        <observer instance="Namespace\Module\Observer\RedirectIp" name="namespace_module_observer_controller_actionpredispatch_controller_action_predispatch"/>
    </event>
</config>

Answer 1

Below one you can follow

namespace Custom\Module\Observer;

use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\App\Request\DataPersistorInterface;
use Magento\Framework\App\ObjectManager;

class YourObserver implements ObserverInterface {

    /**
     * @var \Magento\Framework\App\Response\RedirectInterface
     */
    protected $redirect;

    public function __construct(\Magento\Framework\App\Response\RedirectInterface $redirect) {
        $this->redirect = $redirect;
    }

    public function execute(\Magento\Framework\Event\Observer $observer) {

        $actionName = $observer->getEvent()->getRequest()->getFullActionName();
        $controller = $observer->getControllerAction();

        $this->redirect->redirect($controller->getResponse(), $this->redirect->getRefererUrl());
    }
}

Answer 2

set obeject :

//@var \Magento\Backend\Model\View\Result\Redirect $resultRedirect 
    $resultRedirect = $this->resultRedirectFactory->create();

then just use setPath() method

return $resultRedirect->setPath('*/*/');