[FEATURE] Added configurable delay for response calculation

Refs #1

Classes/Hooks/Form.php

@@ -6,6 +6,7 @@
 
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Log\LoggerInterface;
+use TYPO3\CMS\Core\Configuration\ExtensionConfiguration;
 use TYPO3\CMS\Core\Log\LogManager;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 use TYPO3\CMS\Extbase\Validation\Validator\NotEmptyValidator;
@@ -28,14 +29,24 @@ public function afterInitializeCurrentPage(FormRuntime $runtime, ?Page $currentP
     {
         $pageObject = $currentPage ?? $page;
 
+        // Set delay for initial form (no delay for re-submission of form)
+        $extensionSettings = GeneralUtility::makeInstance(ExtensionConfiguration::class)->get('form_crshield');
+        $delay = $runtime->getFormSession() === null ? (int)($extensionSettings['crJavaScriptDelay'] ?? 0) : 0;
+
         if ($pageObject) {
             $pageMaxLifetime = $this->getPageMaxLifetime($runtime->getRequest());
             $expirationTime = time() + $pageMaxLifetime;
             $challenge = $expirationTime . '|' . GeneralUtility::hmac($expirationTime, $runtime->getIdentifier());
 
             $newElement = $pageObject->createElement(self::FIELD_ID, 'Hidden');
             $newElement->addValidator(new NotEmptyValidator());
-            $newElement->setProperty('fluidAdditionalAttributes', ['data-cr-challenge' => base64_encode($challenge)]);
+            $newElement->setProperty(
+                'fluidAdditionalAttributes',
+                [
+                    'data-cr-challenge' => base64_encode($challenge),
+                    'data-cr-delay' => $delay,
+                ]
+            );
         }
 
         return $currentPage;

README.md

@@ -8,27 +8,35 @@ Form challenge/response spam shield
 Form challenge/response spam shield is a TYPO3 extension to prevent automated form submissions
 in TYPO3 form extension. 
 
-### How does it work?
+## How does it work?
 
 Form challenge/response spam shield adds a hidden input field to every form generated by the TYPO3 form
 extension. The input field contains a data-attribute with a challenge. The included JavaScript will
 use the challenge to calculate an expected response which will be checked on every form submission.
 If the expected response is not submitted, validation for the hidden input field is considered as
 failed and no email will be sent.
 
-### Requirements
+In order to make automatic form submissions harder for spambots with active JavaScript, a configurable
+delay for the JavaScript response calculation can be defined in the extension settings (default value: 3 seconds).
+
+## Requirements
 
 The extension uses JavaScript to calculate the expected response, so if JavaScript is disabled on client
 side, form submission will not be possible.
 
 A modern webbrowser is required to run the JavaScript. Internet Explorer < 11 is not supported.
 
-### Installation
+## Installation
 
 Just install the extension on your TYPO3 website using composer or the TYPO3 extension manager.
 No further configuration is required.
 
-### Logging
+## Settings
+
+It is possible to configure the delay in seconds for the JavaScript response calculation. This can be
+done in the extensions settings. The default value is 3 seconds.
+
+## Logging
 
 In order to log failed requests, it is possible to use a dedicated logfile like shown below:
 

Resources/Public/JavaScript/FormCrShield.js

@@ -11,12 +11,16 @@ document.addEventListener('DOMContentLoaded', function () {
   elementsArray.forEach(element => {
     let challengeString = atob(element.getAttribute('data-cr-challenge'));
     let [exp,challenge] = challengeString.split('|');
+    let delay = element.dataset.crDelay;
 
     // ROT13 the challenge - source: https://stackoverflow.com/a/617685/1744743
     let response = challenge.replace(/[a-zA-Z]/g, function (c) {
       return String.fromCharCode((c <= 'Z' ? 90 : 122) >= (c = c.charCodeAt(0) + 13) ? c : c - 26);
     });
 
-    element.value = btoa(exp + '|' + response);
+    // Set calculated response after defined amount of seconds
+    setTimeout(() => {
+      element.value = btoa(exp + '|' + response)
+    }, delay * 1000)
   });
 });

ext_conf_template.txt

@@ -0,0 +1,4 @@
+# settings
+###########################
+# cat=settings/enable/10; type=integer; label=Delay in seconds when response calculation is set using JavaScript
+	crJavaScriptDelay = 3

ext_emconf.php

@@ -10,7 +10,7 @@
     'uploadfolder' => '0',
     'createDirs' => '',
     'clearCacheOnLoad' => 1,
-    'version' => '1.0.0',
+    'version' => '1.1.0',
     'constraints' => [
         'depends' => [
             'typo3' => '11.5.0-11.5.99',