Club Drupal

<?php

/**

 * @file

 * Honeypot module, for deterring spam bots from completing Drupal forms.

 */

/**

 * Implements hook_menu().

 */

function honeypot_menu() {

  $items['admin/config/content/honeypot'] = array(

    'title' => 'Honeypot configuration',

    'description' => 'Configure Honeypot spam prevention and the forms on which Honeypot will be used.',

    'page callback' => 'drupal_get_form',

    'page arguments' => array('honeypot_admin_form'),

    'access arguments' => array('administer honeypot'),

    'file' => 'honeypot.admin.inc',

  );

  return $items;

}

/**

 * Implements hook_permission().

 */

function honeypot_permission() {

  return array(

    'administer honeypot' => array(

      'title' => t('Administer Honeypot'),

      'description' => t('Administer Honeypot-protected forms and settings'),

    ),

    'bypass honeypot protection' => array(

      'title' => t('Bypass Honeypot protection'),

      'description' => t('Bypass Honeypot form protection.'),

    ),

  );

}

/**

 * Implements hook_cron().

 */

function honeypot_cron() {

  // Delete {honeypot_user} entries older than the value of honeypot_expire.

  db_delete('honeypot_user')

    ->condition('timestamp', REQUEST_TIME - variable_get('honeypot_expire', 300), '<')

    ->execute();

  // Regenerate the honeypot css file if it does not exist or is outdated.

  $honeypot_css = honeypot_get_css_file_path();

  $honeypot_element_name = variable_get('honeypot_element_name', 'url');

  if (!file_exists($honeypot_css) || !honeypot_check_css($honeypot_element_name)) {

    honeypot_create_css($honeypot_element_name);

  }

}

/**

 * Implements hook_form_alter().

 *

 * Add Honeypot features to forms enabled in the Honeypot admin interface.

 */

function honeypot_form_alter(&$form, &$form_state, $form_id) {

  // Don't use for maintenance mode forms (install, update, etc.).

  if (defined('MAINTENANCE_MODE')) {

    return;

  }

  $unprotected_forms = array(

    'user_login',

    'user_login_block',

    'search_form',

    'search_block_form',

    'views_exposed_form',

    'honeypot_admin_form',

  );

  // If configured to protect all forms, add protection to every form.

  if (variable_get('honeypot_protect_all_forms', 0) && !in_array($form_id, $unprotected_forms)) {

    // Don't protect system forms - only admins should have access, and system

    // forms may be programmatically submitted by drush and other modules.

    if (strpos($form_id, 'system_') === FALSE && strpos($form_id, 'search_') === FALSE && strpos($form_id, 'views_exposed_form_') === FALSE) {

      honeypot_add_form_protection($form, $form_state, array('honeypot', 'time_restriction'));

    }

  }

  // Otherwise add form protection to admin-configured forms.

  elseif ($forms_to_protect = honeypot_get_protected_forms()) {

    foreach ($forms_to_protect as $protect_form_id) {

      // For most forms, do a straight check on the form ID.

      if ($form_id == $protect_form_id) {

        honeypot_add_form_protection($form, $form_state, array('honeypot', 'time_restriction'));

      }

      // For webforms use a special check for variable form ID.

      elseif ($protect_form_id == 'webforms' && (strpos($form_id, 'webform_client_form') !== FALSE)) {

        honeypot_add_form_protection($form, $form_state, array('honeypot', 'time_restriction'));

      }

    }

  }

}

/**

 * Implements hook_trigger_info().

 */

function honeypot_trigger_info() {

  return array(

    'honeypot' => array(

      'honeypot_reject' => array(

        'label' => t('Honeypot rejection'),

      ),

    ),

  );

}

/**

 * Implements hook_rules_event_info().

 */

function honeypot_rules_event_info() {

  return array(

    'honeypot_reject' => array(

      'label' => t('Honeypot rejection'),

      'group' => t('Honeypot'),

      'variables' => array(

        'form_id' => array(

          'type' => 'text',

          'label' => t('Form ID of the form the user was disallowed from submitting.'),

        ),

        // Don't provide 'uid' in context because it is available as

        // site:current-user:uid.

        'type' => array(

          'type' => 'text',

          'label' => t('String indicating the reason the submission was blocked.'),

        ),

      ),

    ),

  );

}

/**

 * Build an array of all the protected forms on the site, by form_id.

 *

 * @todo - Add in API call/hook to allow modules to add to this array.

 */

function honeypot_get_protected_forms() {

  $forms = &drupal_static(__FUNCTION__);

  // If the data isn't already in memory, get from cache or look it up fresh.

  if (!isset($forms)) {

    if ($cache = cache_get('honeypot_protected_forms')) {

      $forms = $cache->data;

    }

    else {

      $forms = array();

      // Look up all the honeypot forms in the variables table.

      $result = db_query("SELECT name FROM {variable} WHERE name LIKE 'honeypot_form_%'")->fetchCol();

      // Add each form that's enabled to the $forms array.

      foreach ($result as $variable) {

        if (variable_get($variable, 0)) {

          $forms[] = substr($variable, 14);

        }

      }

      // Save the cached data.

      cache_set('honeypot_protected_forms', $forms, 'cache');

    }

  }

  return $forms;

}

/**

 * Form builder function to add different types of protection to forms.

 *

 * @param array $options

 *   Array of options to be added to form. Currently accepts 'honeypot' and

 *   'time_restriction'.

 *

 * @return array

 *   Returns elements to be placed in a form's elements array to prevent spam.

 */

function honeypot_add_form_protection(&$form, &$form_state, $options = array()) {

  global $user;

  // Allow other modules to alter the protections applied to this form.

  drupal_alter('honeypot_form_protections', $options, $form);

  // Don't add any protections if the user can bypass the Honeypot.

  if (user_access('bypass honeypot protection')) {

    return;

  }

  // Build the honeypot element.

  if (in_array('honeypot', $options)) {

    // Get the element name (default is generic 'url').

    $honeypot_element = variable_get('honeypot_element_name', 'url');

    // Add 'autocomplete="off"' if configured.

    $attributes = array();

    if (variable_get('honeypot_autocomplete_attribute', 1)) {

      $attributes = array('autocomplete' => 'off');

    }

    // Get the path to the honeypot css file.

    $honeypot_css = honeypot_get_css_file_path();

    // Build the honeypot element.

    $honeypot_class = $honeypot_element . '-textfield';

    $form[$honeypot_element] = array(

      '#type' => 'textfield',

      '#title' => t('Leave this field blank'),

      '#size' => 20,

      '#weight' => 100,

      '#attributes' => $attributes,

      '#element_validate' => array('_honeypot_honeypot_validate'),

      '#prefix' => '<div class="' . $honeypot_class . '">',

      '#suffix' => '</div>',

      // Hide honeypot using CSS.

      '#attached' => array(

        'css' => array(

          'data' => $honeypot_css,

        ),

      ),

    );

  }

  // Build the time restriction element (if it's not disabled).

  if (in_array('time_restriction', $options) && variable_get('honeypot_time_limit', 5) != 0) {

    // Set the current time in a hidden value to be checked later.

    $form['honeypot_time'] = array(

      '#type' => 'hidden',

      '#title' => t('Timestamp'),

      '#default_value' => honeypot_get_signed_timestamp(REQUEST_TIME),

      '#element_validate' => array('_honeypot_time_restriction_validate'),

    );

    // Disable page caching to make sure timestamp isn't cached.

    if (user_is_anonymous()) {

      drupal_page_is_cacheable(FALSE);

    }

  }

  // Allow other modules to react to addition of form protection.

  if (!empty($options)) {

    module_invoke_all('honeypot_add_form_protection', $options, $form);

  }

}

/**

 * Validate honeypot field.

 */

function _honeypot_honeypot_validate($element, &$form_state) {

  // Get the honeypot field value.

  $honeypot_value = $element['#value'];

  // Make sure it's empty.

  if (!empty($honeypot_value)) {

    _honeypot_log($form_state['values']['form_id'], 'honeypot');

    form_set_error('', t('There was a problem with your form submission. Please refresh the page and try again.'));

  }

}

/**

 * Validate honeypot's time restriction field.

 */

function _honeypot_time_restriction_validate($element, &$form_state) {

  if (!empty($form_state['programmed'])) {

    // Don't do anything if the form was submitted programmatically.

    return;

  }

  // Don't do anything if the triggering element is a preview button.

  if ($form_state['triggering_element']['#value'] == t('Preview')) {

    return;

  }

  // Get the time value.

  $honeypot_time = honeypot_get_time_from_signed_timestamp($form_state['values']['honeypot_time']);

  // Get the honeypot_time_limit.

  $time_limit = honeypot_get_time_limit($form_state['values']);

  // Make sure current time - (time_limit + form time value) is greater than 0.

  // If not, throw an error.

  if (!$honeypot_time || REQUEST_TIME < ($honeypot_time + $time_limit)) {

    _honeypot_log($form_state['values']['form_id'], 'honeypot_time');

    // Get the time limit again, since it increases after first failure.

    $time_limit = honeypot_get_time_limit($form_state['values']);

    $form_state['values']['honeypot_time'] = honeypot_get_signed_timestamp(REQUEST_TIME);

    form_set_error('', t('There was a problem with your form submission. Please wait @limit seconds and try again.', array('@limit' => $time_limit)));

  }

}

/**

 * Log blocked form submissions.

 *

 * @param string $form_id

 *   Form ID for the form on which submission was blocked.

 * @param string $type

 *   String indicating the reason the submission was blocked. Allowed values:

 *     - honeypot: If honeypot field was filled in.

 *     - honeypot_time: If form was completed before the configured time limit.

 */

function _honeypot_log($form_id, $type) {

  honeypot_log_failure($form_id, $type);

  if (variable_get('honeypot_log', 0)) {

    $variables = array(

      '%form'  => $form_id,

      '@cause' => ($type == 'honeypot') ? t('submission of a value in the honeypot field') : t('submission of the form in less than minimum required time'),

    );

    watchdog('honeypot', 'Blocked submission of %form due to @cause.', $variables);

  }

}

/**

 * Look up the time limit for the current user.

 *

 * @param array $form_values

 *   Array of form values (optional).

 */

function honeypot_get_time_limit($form_values = array()) {

  global $user;

  $honeypot_time_limit = variable_get('honeypot_time_limit', 5);

  // Only calculate time limit if honeypot_time_limit has a value > 0.

  if ($honeypot_time_limit) {

    $expire_time = variable_get('honeypot_expire', 300);

    // Query the {honeypot_user} table to determine the number of failed

    // submissions for the current user.

    $query = db_select('honeypot_user', 'hs')

      ->condition('uid', $user->uid)

      ->condition('timestamp', REQUEST_TIME - $expire_time, '>');

    // For anonymous users, take the hostname into account.

    if ($user->uid === 0) {

      $query->condition('hostname', ip_address());

    }

    $number = $query->countQuery()->execute()->fetchField();

    // Don't add more than 30 days' worth of extra time.

    $honeypot_time_limit = (int) min($honeypot_time_limit + exp($number) - 1, 2592000);

    $additions = module_invoke_all('honeypot_time_limit', $honeypot_time_limit, $form_values, $number);

    if (count($additions)) {

      $honeypot_time_limit += array_sum($additions);

    }

  }

  return $honeypot_time_limit;

}

/**

 * Log the failed submision with timestamp and hostname.

 *

 * @param string $form_id

 *   Form ID for the rejected form submission.

 * @param string $type

 *   String indicating the reason the submission was blocked. Allowed values:

 *     - honeypot: If honeypot field was filled in.

 *     - honeypot_time: If form was completed before the configured time limit.

 */

function honeypot_log_failure($form_id, $type) {

  global $user;

  db_insert('honeypot_user')

    ->fields(array(

      'uid' => $user->uid,

      'hostname' => ip_address(),

      'timestamp' => REQUEST_TIME,

    ))

    ->execute();

  // Allow other modules to react to honeypot rejections.

  module_invoke_all('honeypot_reject', $form_id, $user->uid, $type);

  // Trigger honeypot_reject action.

  if (module_exists('trigger')) {

    $aids = trigger_get_assigned_actions('honeypot_reject');

    $context = array(

      'group' => 'honeypot',

      'hook' => 'honeypot_reject',

      'form_id' => $form_id,

      // Do not provide $user in context because it is available as a global.

      'type' => $type,

    );

    // Honeypot does not act on any specific object.

    $object = NULL;

    actions_do(array_keys($aids), $object, $context);

  }

  // Trigger rules honeypot_reject event.

  if (module_exists('rules')) {

    rules_invoke_event('honeypot_reject', $form_id, $type);

  }

}

/**

 * Retrieve the location of the Honeypot CSS file.

 *

 * @return string

 *   The path to the honeypot.css file.

 */

function honeypot_get_css_file_path() {

  return variable_get('file_public_path', conf_path() . '/files') . '/honeypot/honeypot.css';

}

/**

 * Create CSS file to hide the Honeypot field.

 *

 * @param string $element_name

 *   The honeypot element class name (e.g. 'url').

 */

function honeypot_create_css($element_name) {

  $path = 'public://honeypot';

  if (!file_prepare_directory($path, FILE_CREATE_DIRECTORY)) {

    drupal_set_message(t('Unable to create Honeypot CSS directory, %path. Check the permissions on your files directory.', array('%path' => file_uri_target($path))), 'error');

  }

  else {

    $filename = $path . '/honeypot.css';

    $data = '.' . $element_name . '-textfield { display: none !important; }';

    file_unmanaged_save_data($data, $filename, FILE_EXISTS_REPLACE);

  }

}

/**

 * Check Honeypot's CSS file for a given Honeypot element name.

 *

 * This function assumes the Honeypot CSS file already exists.

 *

 * @param string $element_name

 *   The honeypot element class name (e.g. 'url').

 *

 * @return bool

 *   TRUE if CSS is has element class name, FALSE if not.

 */

function honeypot_check_css($element_name) {

  $path = honeypot_get_css_file_path();

  $handle = fopen($path, 'r');

  $contents = fread($handle, filesize($path));

  fclose($handle);

  if (strpos($contents, $element_name) === 1) {

    return TRUE;

  }

  return FALSE;

}

/**

 * Sign the timestamp $time.

 *

 * @param mixed $time

 *   The timestamp to sign.

 *

 * @return string

 *   A signed timestamp in the form timestamp|HMAC.

 */

function honeypot_get_signed_timestamp($time) {

  return $time . '|' . drupal_hmac_base64($time, drupal_get_private_key());

}

/**

 * Validate a signed timestamp.

 *

 * @param string $signed_timestamp

 *   A timestamp concateneted with the signature

 *

 * @return int

 *   The timestamp if the signature is correct, 0 otherwise.

 */

function honeypot_get_time_from_signed_timestamp($signed_timestamp) {

  $honeypot_time = 0;

  // Fail fast if timestamp was forged or saved with an older Honeypot version.

  if (strpos($signed_timestamp, '|') === FALSE) {

    return $honeypot_time;

  }

  list($timestamp, $received_hmac) = explode('|', $signed_timestamp);

  if ($timestamp && $received_hmac) {

    $calculated_hmac = drupal_hmac_base64($timestamp, drupal_get_private_key());

    // Prevent leaking timing information, compare second order hmacs.

    $random_key = drupal_random_bytes(32);

    if (drupal_hmac_base64($calculated_hmac, $random_key) === drupal_hmac_base64($received_hmac, $random_key)) {

      $honeypot_time = $timestamp;

    }

  }

  return $honeypot_time;

}