materio-base-d7/sites/all/modules/contrib/users/friendly_register/friendly_register.module

<?php

/**
 * @file
 * Primary logic for the friendly_register module that allows for checking of username and email.
 */

define('FRIENDLY_REGISTER_MAX_HITS', 300);
define('FRIENDLY_REGISTER_EXPIRES', 86400);

/**
 * Implements hook_menu().
 */
function friendly_register_menu() {
  $items['ajax/check-email'] = array(
    'page callback' => 'friendly_register_check_email',
    'page arguments' => array(2),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['ajax/check-user'] = array(
    'page callback' => 'friendly_register_check_user',
    'page arguments' => array(2),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  return $items;
}

/**
 * Implements hook_permission().
 */
function friendly_register_permission() {
  return array(
    'ignore flood' =>  array(
      'title' => t('Ignore Flood Checking'),
      'description' => t('Allows users to have unlimited checks against friendly register.'),
      'restrict access' => FALSE,
    ),
  );
}

/**
 * Implements hook_cron().
 */
function friendly_register_cron() {
  $expires = REQUEST_TIME - FRIENDLY_REGISTER_EXPIRES;
  db_delete('friendly_register_flood')
    ->condition('lasthit', $expires, '<=')
    ->execute();
}

/**
 * Implements hook_FORM_form_alter().
 */
function friendly_register_form_user_register_form_alter(&$form, &$form_state, $form_id) {
  $path = drupal_get_path('module', 'friendly_register');
  drupal_add_js($path . '/js/friendly_register.js', 'file');
  drupal_add_css($path . '/css/friendly_register.css');
}

function friendly_register_check_email($address) {
  // Check if it is a valid email address. No need to check if it is not
  if (valid_email_address($address)) {
    drupal_json_output(_friendly_register_check_field('mail', $address));
  }
  else {
    // This flag will return incomplete so the user doesn't see an error
    // if they are just starting to enter in their email address
    drupal_json_output(array('available' => 'incomplete'));
  }
}

function friendly_register_check_user($username) {
  drupal_json_output(_friendly_register_check_field('name', $username));
}

function _friendly_register_check_field($field_name, $value) {
  if (_friendly_register_check_flood()) {
    $result = db_query("SELECT uid FROM {users} WHERE " . $field_name . " = :value", array(':value' => $value))->fetchField();
    return array('available' => ($result == NULL));
  }
  else {
    return array('flood' => TRUE);
  }
}

function _friendly_register_check_flood() {
  if (user_access('ignore flood')) {
    return TRUE;
  }
  else {
    $ip = ip_address();
    $q = 'SELECT hits FROM {friendly_register_flood} WHERE ip = :ip';
    $hits = db_query($q, array(':ip' => $ip))->fetchField();
    if ($hits == NULL) {
      $id = db_insert('friendly_register_flood')
        ->fields(array(
            'ip' => $ip,
            'hits' => 1,
            'lasthit' => REQUEST_TIME,
      ))->execute();
    }
    else {
      db_update('friendly_register_flood')
      ->expression('hits', 'hits + 1')
      ->expression('lasthit', REQUEST_TIME)
      ->condition('ip', $ip)
      ->execute();
    }
    return $hits < FRIENDLY_REGISTER_MAX_HITS;
  }
}