Merge pull request #167 from OS2Forms/f/OS-110

Digital Signature

Author: stankut

CHANGELOG.md

@@ -25,6 +25,7 @@ before starting to add changes. Use example [placed in the end of the page](#exa
   - Fix digital post commands
   - Updated versions in GitHub Actions `uses` steps
 - Updating the display of os2forms package on the status page
+- Adding os2forms_digital_signature module
 
 ## [4.0.0] 2025-03-06
 

modules/os2forms_attachment/os2forms_attachment.services.yml

@@ -1,4 +1,4 @@
 services:
   os2forms_attachment.print_builder:
     class: Drupal\os2forms_attachment\Os2formsAttachmentPrintBuilder
-    arguments: ['@entity_print.renderer_factory', '@event_dispatcher', '@string_translation']
+    arguments: ['@entity_print.renderer_factory', '@event_dispatcher', '@string_translation', '@file_system']

modules/os2forms_attachment/src/Element/AttachmentElement.php

@@ -20,6 +20,7 @@ public function getInfo() {
     return parent::getInfo() + [
       '#view_mode' => 'html',
       '#export_type' => 'pdf',
+      '#digital_signature' => FALSE,
       '#template' => '',
     ];
   }
@@ -28,6 +29,8 @@ public function getInfo() {
    * {@inheritdoc}
    */
   public static function getFileContent(array $element, WebformSubmissionInterface $webform_submission) {
+    $submissionUuid = $webform_submission->uuid();
+
     // Override webform settings.
     static::overrideWebformSettings($element, $webform_submission);
 
@@ -51,18 +54,43 @@ public static function getFileContent(array $element, WebformSubmissionInterface
     \Drupal::request()->request->set('_webform_submissions_view_mode', $view_mode);
 
     if ($element['#export_type'] === 'pdf') {
-      // Get scheme.
-      $scheme = 'temporary';
-
-      // Get filename.
-      $file_name = 'webform-entity-print-attachment--' . $webform_submission->getWebform()->id() . '-' . $webform_submission->id() . '.pdf';
-
-      // Save printable document.
-      $print_engine = $print_engine_manager->createSelectedInstance($element['#export_type']);
-      $temporary_file_path = $print_builder->savePrintable([$webform_submission], $print_engine, $scheme, $file_name);
-      if ($temporary_file_path) {
-        $contents = file_get_contents($temporary_file_path);
-        \Drupal::service('file_system')->delete($temporary_file_path);
+      $file_path = NULL;
+
+      // If attachment with digital signatur, check if we already have one.
+      if (isset($element['#digital_signature']) && $element['#digital_signature']) {
+        // Get scheme.
+        $scheme = 'private';
+
+        // Get filename.
+        $file_name = 'webform/' . $webform_submission->getWebform()->id() . '/digital_signature/' . $submissionUuid . '.pdf';
+        $file_path = "$scheme://$file_name";
+      }
+
+      if (!$file_path || !file_exists($file_path)) {
+        // Get scheme.
+        $scheme = 'temporary';
+        // Get filename.
+        $file_name = 'webform-entity-print-attachment--' . $webform_submission->getWebform()->id() . '-' . $webform_submission->id() . '.pdf';
+
+        // Save printable document.
+        $print_engine = $print_engine_manager->createSelectedInstance($element['#export_type']);
+
+        // Adding digital signature.
+        if (isset($element['#digital_signature']) && $element['#digital_signature']) {
+          $file_path = $print_builder->savePrintableDigitalSignature([$webform_submission], $print_engine, $scheme, $file_name);
+        }
+        else {
+          $file_path = $print_builder->savePrintable([$webform_submission], $print_engine, $scheme, $file_name);
+        }
+      }
+
+      if ($file_path) {
+        $contents = file_get_contents($file_path);
+
+        // Deleting temporary file.
+        if ($scheme == 'temporary') {
+          \Drupal::service('file_system')->delete($file_path);
+        }
       }
       else {
         // Log error.

modules/os2forms_attachment/src/Os2formsAttachmentPrintBuilder.php

@@ -3,14 +3,28 @@
 namespace Drupal\os2forms_attachment;
 
 use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\File\FileExists;
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\entity_print\Event\PreSendPrintEvent;
+use Drupal\entity_print\Event\PrintEvents;
 use Drupal\entity_print\Plugin\PrintEngineInterface;
 use Drupal\entity_print\PrintBuilder;
+use Drupal\entity_print\Renderer\RendererFactoryInterface;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 
 /**
  * The OS2Forms attachment print builder service.
  */
 class Os2formsAttachmentPrintBuilder extends PrintBuilder {
 
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(RendererFactoryInterface $renderer_factory, EventDispatcherInterface $event_dispatcher, TranslationInterface $string_translation, protected readonly FileSystemInterface $file_system) {
+    parent::__construct($renderer_factory, $event_dispatcher, $string_translation);
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -27,10 +41,56 @@ public function printHtml(EntityInterface $entity, $use_default_css = TRUE, $opt
     return $renderer->generateHtml([$entity], $render, $use_default_css, $optimize_css);
   }
 
+  /**
+   * Modified version of the original savePrintable() function.
+   *
+   * The only difference is modified call to prepareRenderer with digitalPost
+   * flag TRUE.
+   *
+   * @see PrintBuilder::savePrintable()
+   *
+   * @return string
+   *   FALSE or the URI to the file. E.g. public://my-file.pdf.
+   */
+  public function savePrintableDigitalSignature(array $entities, PrintEngineInterface $print_engine, $scheme = 'public', $filename = FALSE, $use_default_css = TRUE) {
+    $renderer = $this->prepareRenderer($entities, $print_engine, $use_default_css, TRUE);
+
+    // Allow other modules to alter the generated Print object.
+    $this->dispatcher->dispatch(new PreSendPrintEvent($print_engine, $entities), PrintEvents::PRE_SEND);
+
+    // If we didn't have a URI passed in the generate one.
+    if (!$filename) {
+      $filename = $renderer->getFilename($entities) . '.' . $print_engine->getExportType()->getFileExtension();
+    }
+
+    $uri = "$scheme://$filename";
+
+    // Save the file.
+    return $this->file_system->saveData($print_engine->getBlob(), $uri, FileExists::Replace);
+  }
+
   /**
    * {@inheritdoc}
    */
-  protected function prepareRenderer(array $entities, PrintEngineInterface $print_engine, $use_default_css) {
+
+  /**
+   * Override prepareRenderer() the print engine with the passed entities.
+   *
+   * @param array $entities
+   *   An array of entities.
+   * @param \Drupal\entity_print\Plugin\PrintEngineInterface $print_engine
+   *   The print engine.
+   * @param bool $use_default_css
+   *   TRUE if we want the default CSS included.
+   * @param bool $digitalSignature
+   *   If the digital signature message needs to be added.
+   *
+   * @return \Drupal\entity_print\Renderer\RendererInterface
+   *   A print renderer.
+   *
+   * @see PrintBuilder::prepareRenderer
+   */
+  protected function prepareRenderer(array $entities, PrintEngineInterface $print_engine, $use_default_css, $digitalSignature = FALSE) {
     if (empty($entities)) {
       throw new \InvalidArgumentException('You must pass at least 1 entity');
     }
@@ -50,6 +110,9 @@ protected function prepareRenderer(array $entities, PrintEngineInterface $print_
     // structure. That margin is automatically added in PDF and PDF only.
     $generatedHtml = (string) $renderer->generateHtml($entities, $render, $use_default_css, TRUE);
     $generatedHtml .= "<style>fieldset legend {margin-left: -12px;}</style>";
+    if ($digitalSignature) {
+      $generatedHtml .= $this->t('You can validate the signature on this PDF file via validering.nemlog-in.dk.');
+    }
 
     $print_engine->addPage($generatedHtml);
 

modules/os2forms_attachment/src/Plugin/WebformElement/AttachmentElement.php

@@ -27,6 +27,7 @@ protected function defineDefaultProperties() {
       'view_mode' => 'html',
       'template' => '',
       'export_type' => '',
+      'digital_signature' => '',
       'exclude_empty' => '',
       'exclude_empty_checkbox' => '',
       'excluded_elements' => '',
@@ -88,6 +89,11 @@ public function form(array $form, FormStateInterface $form_state) {
         'html' => $this->t('HTML'),
       ],
     ];
+    $form['attachment']['digital_signature'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Digital signature'),
+    ];
+
     // Set #access so that help is always visible.
     WebformElementHelper::setPropertyRecursive($form['attachment']['help'], '#access', TRUE);
 

modules/os2forms_digital_signature/README.md

@@ -0,0 +1,40 @@
+# OS2Forms Digital Signature module
+
+## Module purpose
+
+This module provides functionality for adding digital signature to the webform PDF submissions.
+
+## How does it work
+
+### Activating Digital Signature
+
+1. Add the OS2forms attachment element to the form.
+2. Indicate that the OS2Forms attachment requires a digital signature.
+3. Add the Digital Signature Handler to the webform.
+4. If the form requires an email handler, ensure the trigger is set to **...when submission is locked** in the handler’s
+*Additional settings*.
+
+### Flow Explained
+
+1. Upon form submission, a PDF is generated, saved in the private directory, and sent to the signature service via URL.
+2. The user is redirected to the signature service to provide their signature.
+3. After signing, the user is redirected back to the webform solution.
+4. The signed PDF is downloaded and stored in Drupal’s private directory.
+5. When a submission PDF is requested (e.g., via download link or email), the signed PDF is served instead of generating
+a new one on the fly.
+
+## Settings page
+
+URL: `admin/os2forms_digital_signature/settings`
+
+- **Signature server URL**
+
+  The URL of the service providing digital signature. This is the example of a known service [https://signering.bellcom.dk/sign.php?](https://signering.bellcom.dk/sign.php?)
+
+- **Hash Salt used for signature**
+
+  Must match hash salt on the signature server
+
+- **List IPs which can download unsigned PDF submissions**
+
+  Only requests from this IP will be able to download PDF which are to be signed.

modules/os2forms_digital_signature/os2forms_digital_signature.info.yml

@@ -0,0 +1,9 @@
+name: 'OS2Forms Digital Signature'
+type: module
+description: 'Provides digital signature functionality'
+package: 'OS2Forms'
+core_version_requirement: ^9 || ^10
+dependencies:
+  - 'webform:webform'
+
+configure: os2forms_digital_signature.settings

modules/os2forms_digital_signature/os2forms_digital_signature.links.menu.yml

@@ -0,0 +1,5 @@
+os2forms_digital_signature.admin.settings:
+  title: OS2Forms digital signature
+  description: Configure the OS2Forms digital signature module
+  parent: system.admin_config_system
+  route_name: os2forms_digital_signature.settings

modules/os2forms_digital_signature/os2forms_digital_signature.module

@@ -0,0 +1,77 @@
+<?php
+
+/**
+ * @file
+ * This module enables Digital Signature functionality for Webforms.
+ */
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\StreamWrapper\StreamWrapperManager;
+use Drupal\os2forms_digital_signature\Form\SettingsForm;
+
+/**
+ * Implements hook_cron().
+ *
+ * Deletes stalled webform submissions that were left unsigned.
+ */
+function os2forms_digital_signature_cron() {
+  /** @var \Drupal\os2forms_digital_signature\Service\SigningService $service */
+  $service = \Drupal::service('os2forms_digital_signature.signing_service');
+  $service->deleteStalledSubmissions();
+}
+
+/**
+ * Implements hook_webform_submission_form_alter().
+ *
+ * Replaces submit button title, if digital signature present.
+ */
+function os2forms_digital_signature_webform_submission_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
+  /** @var \Drupal\webform\WebformSubmissionInterface Interface $webformSubmission */
+  $webformSubmission = $form_state->getFormObject()->getEntity();
+  /** @var \Drupal\webform\WebformInterface $webform */
+  $webform = $webformSubmission->getWebform();
+
+  // Checking for os2forms_digital_signature handler presence.
+  foreach ($webform->getHandlers()->getConfiguration() as $handlerConf) {
+    if ($handlerConf['id'] == 'os2forms_digital_signature') {
+      $config = \Drupal::config('webform.settings');
+      $settings = $config->get('settings');
+
+      // Checking if the title has not been overridden.
+      if ($settings['default_submit_button_label'] == $form['actions']['submit']['#value']) {
+        $form['actions']['submit']['#value'] = t('Sign and submit');
+      }
+    }
+  }
+}
+
+/**
+ * Implements hook_file_download().
+ *
+ * Custom access control for private files.
+ */
+function os2forms_digital_signature_file_download($uri) {
+  // Only operate on files in the private directory.
+  if (StreamWrapperManager::getScheme($uri) === 'private' && str_starts_with(StreamWrapperManager::getTarget($uri), 'signing/')) {
+    // Get allowed IPs settings.
+    $config = \Drupal::config(SettingsForm::$configName);
+    $allowedIps = $config->get('os2forms_digital_signature_submission_allowed_ips');
+
+    $allowedIpsArr = explode(',', $allowedIps);
+    $remoteIp = Drupal::request()->getClientIp();
+
+    // IP list is empty, or request IP is allowed.
+    if (empty($allowedIpsArr) || in_array($remoteIp, $allowedIpsArr)) {
+      $basename = basename($uri);
+      return [
+        'Content-disposition' => 'attachment; filename="' . $basename . '"',
+      ];
+    }
+
+    // Otherwise - Deny access.
+    return -1;
+  }
+
+  // Not submission file, allow normal access.
+  return NULL;
+}

modules/os2forms_digital_signature/os2forms_digital_signature.routing.yml

@@ -0,0 +1,15 @@
+# Webform os2forms_attachment_component routes.
+os2forms_digital_signature.sign_callback:
+  path: '/os2forms_digital_signature/{uuid}/{hash}/sign_callback/{fid}'
+  defaults:
+    _controller: '\Drupal\os2forms_digital_signature\Controller\DigitalSignatureController::signCallback'
+    fid: ''
+  requirements:
+    _permission: 'access content'
+os2forms_digital_signature.settings:
+  path: '/admin/os2forms_digital_signature/settings'
+  defaults:
+    _form: '\Drupal\os2forms_digital_signature\Form\SettingsForm'
+    _title: 'Digital signature settings'
+  requirements:
+    _permission: 'administer site configuration'