/**
 * Processes new site registrations.
 *
 * Checks the data provided by the user during blog signup. Verifies
 * the validity and uniqueness of blog paths and domains.
 *
 * This function prevents the current user from registering a new site
 * with a blogname equivalent to another user's login name. Passing the
 * $user parameter to the function, where $user is the other user, is
 * effectively an override of this limitation.
 *
 * Filter 'wpmu_validate_blog_signup' if you want to modify
 * the way that WordPress validates new site signups.
 *
 * @since MU
 *
 * @global wpdb   $wpdb
 * @global string $domain
 *
 * @param string         $blogname   The blog name provided by the user. Must be unique.
 * @param string         $blog_title The blog title provided by the user.
 * @param WP_User|string $user       Optional. The user object to check against the new site name.
 * @return array Contains the new site data and error messages.
 */
function wpmu_validate_blog_signup($blogname, $blog_title, $user = '')
{
    global $wpdb, $domain;
    $current_site = get_current_site();
    $base = $current_site->path;
    $blog_title = strip_tags($blog_title);
    $errors = new WP_Error();
    $illegal_names = get_site_option('illegal_names');
    if ($illegal_names == false) {
        $illegal_names = array('www', 'web', 'root', 'admin', 'main', 'invite', 'administrator');
        add_site_option('illegal_names', $illegal_names);
    }
    /*
     * On sub dir installs, some names are so illegal, only a filter can
     * spring them from jail.
     */
    if (!is_subdomain_install()) {
        $illegal_names = array_merge($illegal_names, get_subdirectory_reserved_names());
    }
    if (empty($blogname)) {
        $errors->add('blogname', __('Please enter a site name.'));
    }
    if (preg_match('/[^a-z0-9]+/', $blogname)) {
        $errors->add('blogname', __('Only lowercase letters (a-z) and numbers are allowed.'));
    }
    if (in_array($blogname, $illegal_names)) {
        $errors->add('blogname', __('That name is not allowed.'));
    }
    if (strlen($blogname) < 4 && !is_super_admin()) {
        $errors->add('blogname', __('Site name must be at least 4 characters.'));
    }
    if (strpos($blogname, '_') !== false) {
        $errors->add('blogname', __('Sorry, site names may not contain the character &#8220;_&#8221;!'));
    }
    // do not allow users to create a blog that conflicts with a page on the main blog.
    if (!is_subdomain_install() && $wpdb->get_var($wpdb->prepare("SELECT post_name FROM " . $wpdb->get_blog_prefix($current_site->blog_id) . "posts WHERE post_type = 'page' AND post_name = %s", $blogname))) {
        $errors->add('blogname', __('Sorry, you may not use that site name.'));
    }
    // all numeric?
    if (preg_match('/^[0-9]*$/', $blogname)) {
        $errors->add('blogname', __('Sorry, site names must have letters too!'));
    }
    /**
     * Filter the new site name during registration.
     *
     * The name is the site's subdomain or the site's subdirectory
     * path depending on the network settings.
     *
     * @since MU
     *
     * @param string $blogname Site name.
     */
    $blogname = apply_filters('newblogname', $blogname);
    $blog_title = wp_unslash($blog_title);
    if (empty($blog_title)) {
        $errors->add('blog_title', __('Please enter a site title.'));
    }
    // Check if the domain/path has been used already.
    if (is_subdomain_install()) {
        $mydomain = $blogname . '.' . preg_replace('|^www\\.|', '', $domain);
        $path = $base;
    } else {
        $mydomain = "{$domain}";
        $path = $base . $blogname . '/';
    }
    if (domain_exists($mydomain, $path, $current_site->id)) {
        $errors->add('blogname', __('Sorry, that site already exists!'));
    }
    if (username_exists($blogname)) {
        if (!is_object($user) || is_object($user) && $user->user_login != $blogname) {
            $errors->add('blogname', __('Sorry, that site is reserved!'));
        }
    }
    // Has someone already signed up for this domain?
    $signup = $wpdb->get_row($wpdb->prepare("SELECT * FROM {$wpdb->signups} WHERE domain = %s AND path = %s", $mydomain, $path));
    // TODO: Check email too?
//.........这里部分代码省略.........

}
get_current_screen()->add_help_tab(array('id' => 'overview', 'title' => __('Overview'), 'content' => '<p>' . __('This screen is for Super Admins to add new sites to the network. This is not affected by the registration settings.') . '</p>' . '<p>' . __('If the admin email for the new site does not exist in the database, a new user will also be created.') . '</p>'));
get_current_screen()->set_help_sidebar('<p><strong>' . __('For more information:') . '</strong></p>' . '<p>' . __('<a href="https://codex.wordpress.org/Network_Admin_Sites_Screen" target="_blank">Documentation on Site Management</a>') . '</p>' . '<p>' . __('<a href="https://wordpress.org/support/forum/multisite/" target="_blank">Support Forums</a>') . '</p>');
if (isset($_REQUEST['action']) && 'add-site' == $_REQUEST['action']) {
    check_admin_referer('add-blog', '_wpnonce_add-blog');
    if (!is_array($_POST['blog'])) {
        wp_die(__('Can&#8217;t create an empty site.'));
    }
    $blog = $_POST['blog'];
    $domain = '';
    if (preg_match('|^([a-zA-Z0-9-])+$|', $blog['domain'])) {
        $domain = strtolower($blog['domain']);
    }
    // If not a subdomain install, make sure the domain isn't a reserved word
    if (!is_subdomain_install()) {
        $subdirectory_reserved_names = get_subdirectory_reserved_names();
        if (in_array($domain, $subdirectory_reserved_names)) {
            wp_die(sprintf(__('The following words are reserved for use by WordPress functions and cannot be used as blog names: <code>%s</code>'), implode('</code>, <code>', $subdirectory_reserved_names)));
        }
    }
    $title = $blog['title'];
    $meta = array('public' => 1);
    // Handle translation install for the new site.
    if (!empty($_POST['WPLANG']) && wp_can_install_language_pack()) {
        $language = wp_download_language_pack(wp_unslash($_POST['WPLANG']));
        if ($language) {
            $meta['WPLANG'] = $language;
        }
    }
    if (empty($domain)) {
        wp_die(__('Missing or invalid site address.'));

 /**
  * short url router.
  * Will validation the request path and check so it don't equals `wp-admin`, `wp-content` or `wp`.
  * If any short url exists in the database it will collect the post and try to redirect to the permalink if it not empty.
  *
  * @param object $query
  */
 public function router($query)
 {
     $request = strtolower($query->request);
     $req_uri = $_SERVER['REQUEST_URI'];
     // If the request uri ends with a slash it should
     if (isset($req_uri[strlen($req_uri) - 1]) && $req_uri[strlen($req_uri) - 1] === '/') {
         return $query;
     }
     $subdirectories = ['wp-admin', 'wp-content', 'wp', 'wordpress'];
     if (function_exists('get_subdirectory_reserved_names')) {
         $subdirectories = array_merge($subdirectories, get_subdirectory_reserved_names());
     }
     $paths_to_prevent = apply_filters('short_url_prevent_paths', $subdirectories);
     // If the request don't match with the regex or match 'wp-admin' or 'wp-content' should we not proceeed with the redirect.
     if (!preg_match('/^[a-zA-Z0-9\\-\\_]+$/', $request) && in_array($request, $paths_to_prevent)) {
         return $query;
     }
     $posts = $this->get_posts($request);
     $post = array_shift($posts);
     // Don't allow empty post.
     if (empty($post)) {
         return $query;
     }
     $url = get_permalink($post->ID);
     // If the url is false or empty we should not proceed with the redirect.
     if ($url === false || empty($url)) {
         return $query;
     }
     // Let's redirect baby!
     wp_safe_redirect($url);
     exit;
 }

 /**
  * Is a site URL okay to save?
  *
  * @since 1.8.0
  *
  * @global wpdb $wpdb
  *
  * @param string $domain
  * @param string $path
  * @param string $slug
  *
  * @return boolean
  */
 function wp_validate_site_url($domain, $path, $site_id = 0)
 {
     global $wpdb;
     // Does domain exist on this network
     $exists = domain_exists($domain, $path, get_current_site()->id);
     // Bail if domain is current site ID
     if ($exists == $site_id) {
         return true;
     }
     // Bail if domain exists and it's not this site
     if (true === $exists) {
         return false;
     }
     // Bail if site is in signups table
     $signup = $wpdb->get_row($wpdb->prepare("SELECT * FROM {$wpdb->signups} WHERE domain = %s AND path = %s", $domain, $path));
     if (!empty($signup)) {
         return false;
     }
     // Bail if user is a super admin
     if (is_super_admin()) {
         return true;
     }
     // Get pieces of domain & path
     $paths = explode('/', $path);
     $domains = substr_count($domain, '.') > 1 ? (array) substr($domain, 0, strpos($domain, '.')) : array();
     $pieces = array_filter(array_merge($domains, $paths));
     // Loop through pieces
     foreach ($pieces as $slug) {
         // Bail if empty
         if (empty($slug)) {
             return false;
         }
         // Bail if not lowercase or numbers
         if (preg_match('/[^a-z0-9]+/', $slug)) {
             return false;
         }
         // All numeric?
         if (preg_match('/^[0-9]*$/', $slug)) {
             return false;
         }
         // Bail if less than 4 chars
         if (strlen($slug) < 3) {
             return false;
         }
         // Get illegal names
         $illegal_names = get_site_option('illegal_names');
         // Maybe merge reserved names
         if (!is_subdomain_install()) {
             $illegal_names = array_merge($illegal_names, get_subdirectory_reserved_names());
         }
         // Bail if contains illegal names
         if (in_array($slug, $illegal_names, true)) {
             return false;
         }
         // Bail if username exists
         if (username_exists($slug)) {
             return false;
         }
         // Bail if subdirectory install and page exists on primary site of network
         if (!is_subdomain_install()) {
             switch_to_blog(get_current_site()->blog_id);
             $page = get_page_by_path($slug);
             restore_current_blog();
             if (!empty($page)) {
                 return false;
             }
         }
     }
     // Okay, s'all good
     return true;
 }