Issue #2558243 by Berdir, tim.plunkett: Use a FormElement plugin instead of...

    ->execute();

}

/**

 * Implements hook_element_info().

 */

function captcha_element_info() {

  // Define the CAPTCHA form element with default properties.

  $captcha_element = [

    '#input' => TRUE,

    '#process' => ['captcha_element_process'],

    // The type of challenge: e.g. 'default', 'captcha/Math', etc.

    '#captcha_type' => 'default',

    '#default_value' => '',

    // CAPTCHA in admin mode: presolve the CAPTCHA and always show

    // it (despite previous successful responses).

    '#captcha_admin_mode' => FALSE,

    // The default CAPTCHA validation function.

    // TODO: should this be a single string or an array of strings?

    '#captcha_validate' => 'captcha_validate_strict_equality',

  ];

  // Override the default CAPTCHA validation function for case

  // insensitive validation.

  // TODO: shouldn't this be done somewhere else, e.g. in form_alter?

  if (CAPTCHA_DEFAULT_VALIDATION_CASE_INSENSITIVE == \Drupal::config('captcha.settings')->get('default_validation')) {

    $captcha_element['#captcha_validate'] = 'captcha_validate_case_insensitive_equality';

  }

  return ['captcha' => $captcha_element];

}

/**

 * Process callback for CAPTCHA form element.

 */

function captcha_element_process(array $element, FormStateInterface $form_state, array $complete_form) {

  // Add captcha.inc file

  module_load_include('inc', 'captcha');

  // Add Javascript for general CAPTCHA functionality.

  $element['#attached']['library'][] = 'captcha/base';

  // Get the form ID of the form we are currently processing (which is not

  // necessary the same form that is submitted (if any).

  $this_form_id = $complete_form['form_id']['#value'];

  // Get the CAPTCHA session ID.

  // If there is a submitted form: try to retrieve and reuse the

  // CAPTCHA session ID from the posted data.

  list($posted_form_id, $posted_captcha_sid) = _captcha_get_posted_captcha_info($element, $form_state, $this_form_id);

  if ($this_form_id == $posted_form_id && isset($posted_captcha_sid)) {

    $captcha_sid = $posted_captcha_sid;

  }

  else {

    // Generate a new CAPTCHA session if we could not reuse one from a posted form.

    $captcha_sid = _captcha_generate_captcha_session($this_form_id, CAPTCHA_STATUS_UNSOLVED);

  }

  // Store CAPTCHA session ID as hidden field.

  // Strictly speaking, it is not necessary to send the CAPTCHA session id

  // with the form, as the one time CAPTCHA token (see lower) is enough.

  // However, we still send it along, because it can help debugging

  // problems on live sites with only access to the markup.

  $element['captcha_sid'] = [

    '#type' => 'hidden',

    '#value' => $captcha_sid,

  ];

  // Additional one time CAPTCHA token: store in database and send with form.

  $captcha_token = md5(mt_rand());

  db_update('captcha_sessions')

    ->fields(['token' => $captcha_token])

    ->condition('csid', $captcha_sid)

    ->execute();

  $element['captcha_token'] = [

    '#type' => 'hidden',

    '#value' => $captcha_token,

  ];

  // Get implementing module and challenge for CAPTCHA.

  list($captcha_type_module, $captcha_type_challenge) = _captcha_parse_captcha_type($element['#captcha_type']);

  // Store CAPTCHA information for further processing in

  // - $form_state->get('captcha_info'), which survives a form rebuild (e.g. node

  //   preview), useful in _captcha_get_posted_captcha_info().

  // - $element['#captcha_info'], for post processing functions that do not

  //   receive a $form_state argument (e.g. the pre_render callback).

  $form_state->set('captcha_info', [

    'this_form_id' => $this_form_id,

    'posted_form_id' => $posted_form_id,

    'captcha_sid' => $captcha_sid,

    'module' => $captcha_type_module,

    'captcha_type' => $captcha_type_challenge,

  ]);

  $element['#captcha_info'] = [

    'form_id' => $this_form_id,

    'captcha_sid' => $captcha_sid,

  ];

  if (_captcha_required_for_user($captcha_sid, $this_form_id) || $element['#captcha_admin_mode']) {

    // Generate a CAPTCHA and its solution

    // (note that the CAPTCHA session ID is given as third argument).

    $captcha = \Drupal::moduleHandler()->invoke($captcha_type_module, 'captcha', ['generate', $captcha_type_challenge, $captcha_sid]);

    // @todo Isn't this moment a bit late to figure out that we don't need CAPTCHA?

    if(!isset($captcha)) {

      return $element;

    }

    if (!isset($captcha['form']) || !isset($captcha['solution'])) {

      // The selected module did not return what we expected: log about it and quit.

      \Drupal::logger('CAPTCHA')->error(

        'CAPTCHA problem: unexpected result from hook_captcha() of module %module when trying to retrieve challenge type %type for form %form_id.',

        ['%type' => $captcha_type_challenge, '%module' => $captcha_type_module, '%form_id' => $this_form_id]

      );

      return $element;

    }

    // Add form elements from challenge as children to CAPTCHA form element.

    $element['captcha_widgets'] = $captcha['form'];

    // Add a validation callback for the CAPTCHA form element

    // (when not in admin mode).

    if (!$element['#captcha_admin_mode']) {

      $element['#element_validate'] = ['captcha_validate'];

    }

    // Set a custom CAPTCHA validate function if requested.

    if (isset($captcha['captcha_validate'])) {

      $element['#captcha_validate'] = $captcha['captcha_validate'];

    }

    // Set the theme function.

    $element['#theme'] = 'captcha';

    // Add pre_render callback for additional CAPTCHA processing.

    if (!isset($element['#pre_render'])) {

      $element['#pre_render'] = [];

    }

    $element['#pre_render'][] = 'captcha_pre_render_process';

    // Store the solution in the #captcha_info array.

    $element['#captcha_info']['solution'] = $captcha['solution'];

    // Make sure we can use a top level form value

    // $form_state->getValue('captcha_response'), even if the form has #tree=true.

    $element['#tree'] = FALSE;

  }

  return $element;

}

/**

 * Theme function for a CAPTCHA element.

 *

   * Test the cache tags.

   */

  public function testCacheTags() {

    global $base_path;

    // Check caching without captcha as anonymous user.

    $this->drupalGet('');

    $this->assertEqual($this->drupalGetHeader('x-drupal-cache'), 'MISS');

    // Check that we get a new image when vising the page again.

    $this->drupalGet('');

    $this->assertNotEqual($image_path, (string) $this->xpath('//div[@class="details-wrapper"]/img/@src')[0]);

    // Check image caching.

    $this->drupalGet($image_path);

    // Check image caching, remove the base path since drupalGet() expects the

    // internal path.

    $this->drupalGet(substr($image_path, strlen($base_path)));

    $this->assertResponse(200);

    // Request image twice to make sure no errors happen (due to page caching).

    $this->drupalGet($image_path);

    $this->drupalGet(substr($image_path, strlen($base_path)));

    $this->assertResponse(200);

  }