' . t('This CAPTCHA presents a text field that we expect no one to fill. The text field can be given any name and will be hidden from view using CSS.') . '';
}
}
/**
* Implements hook_menu().
*/
function hidden_captcha_menu() {
$items = array();
$items['admin/config/people/captcha/hidden_captcha'] = array(
'title' => 'Hidden CAPTCHA',
'page callback' => 'drupal_get_form',
'page arguments' => array('hidden_captcha_settings_form'),
'access arguments' => array('administer CAPTCHA settings'),
'type' => MENU_LOCAL_TASK,
'weight' => -10,
);
return $items;
}
/**
* Function for the hidden captcha settings form.
*/
function hidden_captcha_settings_form() {
$form = array();
$form['hidden_captcha_label'] = array(
'#type' => 'textfield',
'#title' => t('Hidden text field label'),
'#description' => t("This is the hidden captcha form field's label, describing the expected input.
It is highly recommended to change it!
The label should be as \"machine-readable\" as possible, encouraging spambots to fill in the field. An example might be a simple math challenge.
The label will only be visible to people who do not have CSS enabled and to robots."),
'#default_value' => variable_get('hidden_captcha_label', 'Website URL'),
);
return system_settings_form($form);
}
/**
* Implements hook_captcha().
*/
function hidden_captcha_captcha($op, $captcha_type = '') {
switch ($op) {
case 'list':
return array('Hidden CAPTCHA');
case 'generate':
if ($captcha_type == 'Hidden CAPTCHA') {
$captcha = array();
$captcha['solution'] = '';
// Ensure this captcha is cacheable.
// @see https://www.drupal.org/project/captcha/issues/2449209
$captcha['cacheable'] = TRUE;
// The CAPTCHA solution provided by hook_captcha() is updated in the
// 'captcha_session' table on pre-render phase of element process.
// @see captcha_pre_render_process()
// @see _captcha_update_captcha_session()
// However, if the cache is enabled, solution would be empty for the
// first attempt of the cached form. For the next attempt, there will
// not be any 'sid' in form_state
// (i.e. $form_state['captcha_info']['captcha_sid'] = null).
// So a new solution would get generated at captcha_element_process().
// The default 'captcha_validate' function,
// captcha_validate_strict_equality(), would fail in this case.
// @see captcha_validate()
// Adding custom validation function to check solution is always empty.
$captcha['captcha_validate'] = 'hidden_captcha_captcha_validate';
$captcha['form']['captcha_response'] = array(
'#type' => 'textfield',
'#title' => variable_get('hidden_captcha_label', 'Website URL'),
'#required' => FALSE,
'#attributes' => array('tabindex' => '-1'),
);
return $captcha;
}
break;
}
}
/**
* CAPTCHA validation callback; checks that the response is empty.
*/
function hidden_captcha_captcha_validate($solution, $captcha_response, $element, $form_state) {
return $captcha_response === '';
}
/**
* Implements hook_theme().
*/
function hidden_captcha_theme() {
return array(
'captcha' => array(
'arguments' => array('element' => NULL),
'function' => 'theme_hidden_captcha_captcha',
),
);
}
/**
* Implements theme_hook().
*/
function theme_hidden_captcha_captcha($element) {
$captcha = theme_captcha($element);
if (strncmp($element["element"]["#captcha_type"], "hidden_captcha/", 15) == 0) {
// Generate a random class name.
$chars = "abcdfghjkmnpqrstvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
$class = "";
for ($i = 0; $i < 64; ++$i) {
$class .= substr($chars, rand(0, strlen($chars) - 1), 1);
}
// Hide the random class via CSS.
// @todo Move the random class to an external file.
drupal_add_css(".$class{width:0;height:0;overflow:hidden;}", "inline");
// HTML for the captcha.
$captcha = "" . $captcha . "
";
}
return $captcha;
}