Evil Twin - Shell
$ EVIL TWIN SHELL $
Path : /home/ahswan/aldenswan.com/wp-includes/

ADMINER AUTO EDIT USER BYPASS DISFUNC BACK CONNECT COMMAND CP RES PASS CSRF
CONFIG CREATE RDP DOMAINS DB DUMP DEL LOGS INFO JUMPING MASS DEF MASS DEL
SYM SYM 403 SYM 404 SYM CONF SMTP UPLOAD VHOST ZONE-H KILL YOUR SELF!
Current File : /home/ahswan/aldenswan.com/wp-includes/ms-functions.php

<?php
/**
 * Multisite WordPress API
 *
 * @package WordPress
 * @subpackage Multisite
 * @since 3.0.0
 */

/**
 * Gets the network's site and user counts.
 *
 * @since MU (3.0.0)
 *
 * @return int[] {
 *     Site and user count for the network.
 *
 *     @type int $blogs Number of sites on the network.
 *     @type int $users Number of users on the network.
 * }
 */
function get_sitestats() {
	$stats = array(
		'blogs' => get_blog_count(),
		'users' => get_user_count(),
	);

	return $stats;
}

/**
 * Get one of a user's active blogs
 *
 * Returns the user's primary blog, if they have one and
 * it is active. If it's inactive, function returns another
 * active blog of the user. If none are found, the user
 * is added as a Subscriber to the Dashboard Blog and that blog
 * is returned.
 *
 * @since MU (3.0.0)
 *
 * @param int $user_id The unique ID of the user
 * @return WP_Site|void The blog object
 */
function get_active_blog_for_user( $user_id ) {
	$blogs = get_blogs_of_user( $user_id );
	if ( empty( $blogs ) ) {
		return;
	}

	if ( ! is_multisite() ) {
		return $blogs[ get_current_blog_id() ];
	}

	$primary_blog = get_user_meta( $user_id, 'primary_blog', true );
	$first_blog   = current( $blogs );
	if ( false !== $primary_blog ) {
		if ( ! isset( $blogs[ $primary_blog ] ) ) {
			update_user_meta( $user_id, 'primary_blog', $first_blog->userblog_id );
			$primary = get_site( $first_blog->userblog_id );
		} else {
			$primary = get_site( $primary_blog );
		}
	} else {
		// TODO: Review this call to add_user_to_blog too - to get here the user must have a role on this blog?
		$result = add_user_to_blog( $first_blog->userblog_id, $user_id, 'subscriber' );

		if ( ! is_wp_error( $result ) ) {
			update_user_meta( $user_id, 'primary_blog', $first_blog->userblog_id );
			$primary = $first_blog;
		}
	}

	if ( ( ! is_object( $primary ) ) || ( 1 == $primary->archived || 1 == $primary->spam || 1 == $primary->deleted ) ) {
		$blogs = get_blogs_of_user( $user_id, true ); // If a user's primary blog is shut down, check their other blogs.
		$ret   = false;
		if ( is_array( $blogs ) && count( $blogs ) > 0 ) {
			foreach ( (array) $blogs as $blog_id => $blog ) {
				if ( get_current_network_id() != $blog->site_id ) {
					continue;
				}
				$details = get_site( $blog_id );
				if ( is_object( $details ) && 0 == $details->archived && 0 == $details->spam && 0 == $details->deleted ) {
					$ret = $details;
					if ( get_user_meta( $user_id, 'primary_blog', true ) != $blog_id ) {
						update_user_meta( $user_id, 'primary_blog', $blog_id );
					}
					if ( ! get_user_meta( $user_id, 'source_domain', true ) ) {
						update_user_meta( $user_id, 'source_domain', $details->domain );
					}
					break;
				}
			}
		} else {
			return;
		}
		return $ret;
	} else {
		return $primary;
	}
}

/**
 * The number of active users in your installation.
 *
 * The count is cached and updated twice daily. This is not a live count.
 *
 * @since MU (3.0.0)
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 * @return int Number of active users on the network.
 */
function get_user_count( $network_id = null ) {
	return get_network_option( $network_id, 'user_count' );
}

/**
 * The number of active sites on your installation.
 *
 * The count is cached and updated twice daily. This is not a live count.
 *
 * @since MU (3.0.0)
 * @since 3.7.0 The `$network_id` parameter has been deprecated.
 * @since 4.8.0 The `$network_id` parameter is now being used.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 * @return int Number of active sites on the network.
 */
function get_blog_count( $network_id = null ) {
	return get_network_option( $network_id, 'blog_count' );
}

/**
 * Gets a blog post from any site on the network.
 *
 * This function is similar to get_post(), except that it can retrieve a post
 * from any site on the network, not just the current site.
 *
 * @since MU (3.0.0)
 *
 * @param int $blog_id ID of the blog.
 * @param int $post_id ID of the post being looked for.
 * @return WP_Post|null WP_Post object on success, null on failure
 */
function get_blog_post( $blog_id, $post_id ) {
	switch_to_blog( $blog_id );
	$post = get_post( $post_id );
	restore_current_blog();

	return $post;
}

/**
 * Adds a user to a blog, along with specifying the user's role.
 *
 * Use the {@see 'add_user_to_blog'} action to fire an event when users are added to a blog.
 *
 * @since MU (3.0.0)
 *
 * @param int    $blog_id ID of the blog the user is being added to.
 * @param int    $user_id ID of the user being added.
 * @param string $role    The role you want the user to have.
 * @return true|WP_Error True on success or a WP_Error object if the user doesn't exist
 *                       or could not be added.
 */
function add_user_to_blog( $blog_id, $user_id, $role ) {
	switch_to_blog( $blog_id );

	$user = get_userdata( $user_id );

	if ( ! $user ) {
		restore_current_blog();
		return new WP_Error( 'user_does_not_exist', __( 'The requested user does not exist.' ) );
	}

	/**
	 * Filters whether a user should be added to a site.
	 *
	 * @since 4.9.0
	 *
	 * @param true|WP_Error $retval  True if the user should be added to the site, error
	 *                               object otherwise.
	 * @param int           $user_id User ID.
	 * @param string        $role    User role.
	 * @param int           $blog_id Site ID.
	 */
	$can_add_user = apply_filters( 'can_add_user_to_blog', true, $user_id, $role, $blog_id );

	if ( true !== $can_add_user ) {
		restore_current_blog();

		if ( is_wp_error( $can_add_user ) ) {
			return $can_add_user;
		}

		return new WP_Error( 'user_cannot_be_added', __( 'User cannot be added to this site.' ) );
	}

	if ( ! get_user_meta( $user_id, 'primary_blog', true ) ) {
		update_user_meta( $user_id, 'primary_blog', $blog_id );
		$site = get_site( $blog_id );
		update_user_meta( $user_id, 'source_domain', $site->domain );
	}

	$user->set_role( $role );

	/**
	 * Fires immediately after a user is added to a site.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int    $user_id User ID.
	 * @param string $role    User role.
	 * @param int    $blog_id Blog ID.
	 */
	do_action( 'add_user_to_blog', $user_id, $role, $blog_id );

	clean_user_cache( $user_id );
	wp_cache_delete( $blog_id . '_user_count', 'blog-details' );

	restore_current_blog();

	return true;
}

/**
 * Remove a user from a blog.
 *
 * Use the {@see 'remove_user_from_blog'} action to fire an event when
 * users are removed from a blog.
 *
 * Accepts an optional `$reassign` parameter, if you want to
 * reassign the user's blog posts to another user upon removal.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $user_id  ID of the user being removed.
 * @param int $blog_id  Optional. ID of the blog the user is being removed from. Default 0.
 * @param int $reassign Optional. ID of the user to whom to reassign posts. Default 0.
 * @return true|WP_Error True on success or a WP_Error object if the user doesn't exist.
 */
function remove_user_from_blog( $user_id, $blog_id = 0, $reassign = 0 ) {
	global $wpdb;

	switch_to_blog( $blog_id );
	$user_id = (int) $user_id;

	/**
	 * Fires before a user is removed from a site.
	 *
	 * @since MU (3.0.0)
	 * @since 5.4.0 Added the `$reassign` parameter.
	 *
	 * @param int $user_id  ID of the user being removed.
	 * @param int $blog_id  ID of the blog the user is being removed from.
	 * @param int $reassign ID of the user to whom to reassign posts.
	 */
	do_action( 'remove_user_from_blog', $user_id, $blog_id, $reassign );

	// If being removed from the primary blog, set a new primary
	// if the user is assigned to multiple blogs.
	$primary_blog = get_user_meta( $user_id, 'primary_blog', true );
	if ( $primary_blog == $blog_id ) {
		$new_id     = '';
		$new_domain = '';
		$blogs      = get_blogs_of_user( $user_id );
		foreach ( (array) $blogs as $blog ) {
			if ( $blog->userblog_id == $blog_id ) {
				continue;
			}
			$new_id     = $blog->userblog_id;
			$new_domain = $blog->domain;
			break;
		}

		update_user_meta( $user_id, 'primary_blog', $new_id );
		update_user_meta( $user_id, 'source_domain', $new_domain );
	}

	// wp_revoke_user( $user_id );
	$user = get_userdata( $user_id );
	if ( ! $user ) {
		restore_current_blog();
		return new WP_Error( 'user_does_not_exist', __( 'That user does not exist.' ) );
	}

	$user->remove_all_caps();

	$blogs = get_blogs_of_user( $user_id );
	if ( count( $blogs ) == 0 ) {
		update_user_meta( $user_id, 'primary_blog', '' );
		update_user_meta( $user_id, 'source_domain', '' );
	}

	if ( $reassign ) {
		$reassign = (int) $reassign;
		$post_ids = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE post_author = %d", $user_id ) );
		$link_ids = $wpdb->get_col( $wpdb->prepare( "SELECT link_id FROM $wpdb->links WHERE link_owner = %d", $user_id ) );

		if ( ! empty( $post_ids ) ) {
			$wpdb->query( $wpdb->prepare( "UPDATE $wpdb->posts SET post_author = %d WHERE post_author = %d", $reassign, $user_id ) );
			array_walk( $post_ids, 'clean_post_cache' );
		}

		if ( ! empty( $link_ids ) ) {
			$wpdb->query( $wpdb->prepare( "UPDATE $wpdb->links SET link_owner = %d WHERE link_owner = %d", $reassign, $user_id ) );
			array_walk( $link_ids, 'clean_bookmark_cache' );
		}
	}

	restore_current_blog();

	return true;
}

/**
 * Get the permalink for a post on another blog.
 *
 * @since MU (3.0.0) 1.0
 *
 * @param int $blog_id ID of the source blog.
 * @param int $post_id ID of the desired post.
 * @return string The post's permalink
 */
function get_blog_permalink( $blog_id, $post_id ) {
	switch_to_blog( $blog_id );
	$link = get_permalink( $post_id );
	restore_current_blog();

	return $link;
}

/**
 * Get a blog's numeric ID from its URL.
 *
 * On a subdirectory installation like example.com/blog1/,
 * $domain will be the root 'example.com' and $path the
 * subdirectory '/blog1/'. With subdomains like blog1.example.com,
 * $domain is 'blog1.example.com' and $path is '/'.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $domain
 * @param string $path   Optional. Not required for subdomain installations.
 * @return int 0 if no blog found, otherwise the ID of the matching blog
 */
function get_blog_id_from_url( $domain, $path = '/' ) {
	$domain = strtolower( $domain );
	$path   = strtolower( $path );
	$id     = wp_cache_get( md5( $domain . $path ), 'blog-id-cache' );

	if ( -1 == $id ) { // Blog does not exist.
		return 0;
	} elseif ( $id ) {
		return (int) $id;
	}

	$args   = array(
		'domain'                 => $domain,
		'path'                   => $path,
		'fields'                 => 'ids',
		'number'                 => 1,
		'update_site_meta_cache' => false,
	);
	$result = get_sites( $args );
	$id     = array_shift( $result );

	if ( ! $id ) {
		wp_cache_set( md5( $domain . $path ), -1, 'blog-id-cache' );
		return 0;
	}

	wp_cache_set( md5( $domain . $path ), $id, 'blog-id-cache' );

	return $id;
}

//
// Admin functions.
//

/**
 * Checks an email address against a list of banned domains.
 *
 * This function checks against the Banned Email Domains list
 * at wp-admin/network/settings.php. The check is only run on
 * self-registrations; user creation at wp-admin/network/users.php
 * bypasses this check.
 *
 * @since MU (3.0.0)
 *
 * @param string $user_email The email provided by the user at registration.
 * @return bool True when the email address is banned, false otherwise.
 */
function is_email_address_unsafe( $user_email ) {
	$banned_names = get_site_option( 'banned_email_domains' );
	if ( $banned_names && ! is_array( $banned_names ) ) {
		$banned_names = explode( "\n", $banned_names );
	}

	$is_email_address_unsafe = false;

	if ( $banned_names && is_array( $banned_names ) && false !== strpos( $user_email, '@', 1 ) ) {
		$banned_names     = array_map( 'strtolower', $banned_names );
		$normalized_email = strtolower( $user_email );

		list( $email_local_part, $email_domain ) = explode( '@', $normalized_email );

		foreach ( $banned_names as $banned_domain ) {
			if ( ! $banned_domain ) {
				continue;
			}

			if ( $email_domain == $banned_domain ) {
				$is_email_address_unsafe = true;
				break;
			}

			$dotted_domain = ".$banned_domain";
			if ( substr( $normalized_email, -strlen( $dotted_domain ) ) === $dotted_domain ) {
				$is_email_address_unsafe = true;
				break;
			}
		}
	}

	/**
	 * Filters whether an email address is unsafe.
	 *
	 * @since 3.5.0
	 *
	 * @param bool   $is_email_address_unsafe Whether the email address is "unsafe". Default false.
	 * @param string $user_email              User email address.
	 */
	return apply_filters( 'is_email_address_unsafe', $is_email_address_unsafe, $user_email );
}

/**
 * Sanitize and validate data required for a user sign-up.
 *
 * Verifies the validity and uniqueness of user names and user email addresses,
 * and checks email addresses against allowed and disallowed domains provided by
 * administrators.
 *
 * The {@see 'wpmu_validate_user_signup'} hook provides an easy way to modify the sign-up
 * process. The value $result, which is passed to the hook, contains both the user-provided
 * info and the error messages created by the function. {@see 'wpmu_validate_user_signup'}
 * allows you to process the data in any way you'd like, and unset the relevant errors if
 * necessary.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $user_name  The login name provided by the user.
 * @param string $user_email The email provided by the user.
 * @return array {
 *     The array of user name, email, and the error messages.
 *
 *     @type string   $user_name     Sanitized and unique username.
 *     @type string   $orig_username Original username.
 *     @type string   $user_email    User email address.
 *     @type WP_Error $errors        WP_Error object containing any errors found.
 * }
 */
function wpmu_validate_user_signup( $user_name, $user_email ) {
	global $wpdb;

	$errors = new WP_Error();

	$orig_username = $user_name;
	$user_name     = preg_replace( '/\s+/', '', sanitize_user( $user_name, true ) );

	if ( $user_name != $orig_username || preg_match( '/[^a-z0-9]/', $user_name ) ) {
		$errors->add( 'user_name', __( 'Usernames can only contain lowercase letters (a-z) and numbers.' ) );
		$user_name = $orig_username;
	}

	$user_email = sanitize_email( $user_email );

	if ( empty( $user_name ) ) {
		$errors->add( 'user_name', __( 'Please enter a username.' ) );
	}

	$illegal_names = get_site_option( 'illegal_names' );
	if ( ! is_array( $illegal_names ) ) {
		$illegal_names = array( 'www', 'web', 'root', 'admin', 'main', 'invite', 'administrator' );
		add_site_option( 'illegal_names', $illegal_names );
	}
	if ( in_array( $user_name, $illegal_names, true ) ) {
		$errors->add( 'user_name', __( 'Sorry, that username is not allowed.' ) );
	}

	/** This filter is documented in wp-includes/user.php */
	$illegal_logins = (array) apply_filters( 'illegal_user_logins', array() );

	if ( in_array( strtolower( $user_name ), array_map( 'strtolower', $illegal_logins ), true ) ) {
		$errors->add( 'user_name', __( 'Sorry, that username is not allowed.' ) );
	}

	if ( ! is_email( $user_email ) ) {
		$errors->add( 'user_email', __( 'Please enter a valid email address.' ) );
	} elseif ( is_email_address_unsafe( $user_email ) ) {
		$errors->add( 'user_email', __( 'You cannot use that email address to signup. We are having problems with them blocking some of our email. Please use another email provider.' ) );
	}

	if ( strlen( $user_name ) < 4 ) {
		$errors->add( 'user_name', __( 'Username must be at least 4 characters.' ) );
	}

	if ( strlen( $user_name ) > 60 ) {
		$errors->add( 'user_name', __( 'Username may not be longer than 60 characters.' ) );
	}

	// All numeric?
	if ( preg_match( '/^[0-9]*$/', $user_name ) ) {
		$errors->add( 'user_name', __( 'Sorry, usernames must have letters too!' ) );
	}

	$limited_email_domains = get_site_option( 'limited_email_domains' );
	if ( is_array( $limited_email_domains ) && ! empty( $limited_email_domains ) ) {
		$limited_email_domains = array_map( 'strtolower', $limited_email_domains );
		$emaildomain           = strtolower( substr( $user_email, 1 + strpos( $user_email, '@' ) ) );
		if ( ! in_array( $emaildomain, $limited_email_domains, true ) ) {
			$errors->add( 'user_email', __( 'Sorry, that email address is not allowed!' ) );
		}
	}

	// Check if the username has been used already.
	if ( username_exists( $user_name ) ) {
		$errors->add( 'user_name', __( 'Sorry, that username already exists!' ) );
	}

	// Check if the email address has been used already.
	if ( email_exists( $user_email ) ) {
		$errors->add( 'user_email', __( 'Sorry, that email address is already used!' ) );
	}

	// Has someone already signed up for this username?
	$signup = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->signups WHERE user_login = %s", $user_name ) );
	if ( $signup instanceof stdClass ) {
		$registered_at = mysql2date( 'U', $signup->registered );
		$now           = time();
		$diff          = $now - $registered_at;
		// If registered more than two days ago, cancel registration and let this signup go through.
		if ( $diff > 2 * DAY_IN_SECONDS ) {
			$wpdb->delete( $wpdb->signups, array( 'user_login' => $user_name ) );
		} else {
			$errors->add( 'user_name', __( 'That username is currently reserved but may be available in a couple of days.' ) );
		}
	}

	$signup = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->signups WHERE user_email = %s", $user_email ) );
	if ( $signup instanceof stdClass ) {
		$diff = time() - mysql2date( 'U', $signup->registered );
		// If registered more than two days ago, cancel registration and let this signup go through.
		if ( $diff > 2 * DAY_IN_SECONDS ) {
			$wpdb->delete( $wpdb->signups, array( 'user_email' => $user_email ) );
		} else {
			$errors->add( 'user_email', __( 'That email address has already been used. Please check your inbox for an activation email. It will become available in a couple of days if you do nothing.' ) );
		}
	}

	$result = array(
		'user_name'     => $user_name,
		'orig_username' => $orig_username,
		'user_email'    => $user_email,
		'errors'        => $errors,
	);

	/**
	 * Filters the validated user registration details.
	 *
	 * This does not allow you to override the username or email of the user during
	 * registration. The values are solely used for validation and error handling.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param array $result {
	 *     The array of user name, email, and the error messages.
	 *
	 *     @type string   $user_name     Sanitized and unique username.
	 *     @type string   $orig_username Original username.
	 *     @type string   $user_email    User email address.
	 *     @type WP_Error $errors        WP_Error object containing any errors found.
	 * }
	 */
	return apply_filters( 'wpmu_validate_user_signup', $result );
}

/**
 * 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 {@see 'wpmu_validate_blog_signup'} if you want to modify
 * the way that WordPress validates new site signups.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb   $wpdb   WordPress database abstraction object.
 * @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 {
 *     Array of domain, path, blog name, blog title, user and error messages.
 *
 *     @type string         $domain     Domain for the site.
 *     @type string         $path       Path for the site. Used in subdirectory installations.
 *     @type string         $blogname   The unique site name (slug).
 *     @type string         $blog_title Blog title.
 *     @type string|WP_User $user       By default, an empty string. A user object if provided.
 *     @type WP_Error       $errors     WP_Error containing any errors found.
 * }
 */
function wpmu_validate_blog_signup( $blogname, $blog_title, $user = '' ) {
	global $wpdb, $domain;

	$current_network = get_network();
	$base            = $current_network->path;

	$blog_title = strip_tags( $blog_title );

	$errors        = new WP_Error();
	$illegal_names = get_site_option( 'illegal_names' );
	if ( false == $illegal_names ) {
		$illegal_names = array( 'www', 'web', 'root', 'admin', 'main', 'invite', 'administrator' );
		add_site_option( 'illegal_names', $illegal_names );
	}

	/*
	 * On sub dir installations, 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', __( 'Site names can only contain lowercase letters (a-z) and numbers.' ) );
	}

	if ( in_array( $blogname, $illegal_names, true ) ) {
		$errors->add( 'blogname', __( 'That name is not allowed.' ) );
	}

	/**
	 * Filters the minimum site name length required when validating a site signup.
	 *
	 * @since 4.8.0
	 *
	 * @param int $length The minimum site name length. Default 4.
	 */
	$minimum_site_name_length = apply_filters( 'minimum_site_name_length', 4 );

	if ( strlen( $blogname ) < $minimum_site_name_length ) {
		/* translators: %s: Minimum site name length. */
		$errors->add( 'blogname', sprintf( _n( 'Site name must be at least %s character.', 'Site name must be at least %s characters.', $minimum_site_name_length ), number_format_i18n( $minimum_site_name_length ) ) );
	}

	// 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_network->site_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!' ) );
	}

	/**
	 * Filters 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 (3.0.0)
	 *
	 * @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_network->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?
	// TODO: Check email too?
	$signup = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->signups WHERE domain = %s AND path = %s", $mydomain, $path ) );
	if ( $signup instanceof stdClass ) {
		$diff = time() - mysql2date( 'U', $signup->registered );
		// If registered more than two days ago, cancel registration and let this signup go through.
		if ( $diff > 2 * DAY_IN_SECONDS ) {
			$wpdb->delete(
				$wpdb->signups,
				array(
					'domain' => $mydomain,
					'path'   => $path,
				)
			);
		} else {
			$errors->add( 'blogname', __( 'That site is currently reserved but may be available in a couple days.' ) );
		}
	}

	$result = array(
		'domain'     => $mydomain,
		'path'       => $path,
		'blogname'   => $blogname,
		'blog_title' => $blog_title,
		'user'       => $user,
		'errors'     => $errors,
	);

	/**
	 * Filters site details and error messages following registration.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param array $result {
	 *     Array of domain, path, blog name, blog title, user and error messages.
	 *
	 *     @type string         $domain     Domain for the site.
	 *     @type string         $path       Path for the site. Used in subdirectory installations.
	 *     @type string         $blogname   The unique site name (slug).
	 *     @type string         $blog_title Blog title.
	 *     @type string|WP_User $user       By default, an empty string. A user object if provided.
	 *     @type WP_Error       $errors     WP_Error containing any errors found.
	 * }
	 */
	return apply_filters( 'wpmu_validate_blog_signup', $result );
}

/**
 * Record site signup information for future activation.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $domain     The requested domain.
 * @param string $path       The requested path.
 * @param string $title      The requested site title.
 * @param string $user       The user's requested login name.
 * @param string $user_email The user's email address.
 * @param array  $meta       Optional. Signup meta data. By default, contains the requested privacy setting and lang_id.
 */
function wpmu_signup_blog( $domain, $path, $title, $user, $user_email, $meta = array() ) {
	global $wpdb;

	$key = substr( md5( time() . wp_rand() . $domain ), 0, 16 );

	/**
	 * Filters the metadata for a site signup.
	 *
	 * The metadata will be serialized prior to storing it in the database.
	 *
	 * @since 4.8.0
	 *
	 * @param array  $meta       Signup meta data. Default empty array.
	 * @param string $domain     The requested domain.
	 * @param string $path       The requested path.
	 * @param string $title      The requested site title.
	 * @param string $user       The user's requested login name.
	 * @param string $user_email The user's email address.
	 * @param string $key        The user's activation key.
	 */
	$meta = apply_filters( 'signup_site_meta', $meta, $domain, $path, $title, $user, $user_email, $key );

	$wpdb->insert(
		$wpdb->signups,
		array(
			'domain'         => $domain,
			'path'           => $path,
			'title'          => $title,
			'user_login'     => $user,
			'user_email'     => $user_email,
			'registered'     => current_time( 'mysql', true ),
			'activation_key' => $key,
			'meta'           => serialize( $meta ),
		)
	);

	/**
	 * Fires after site signup information has been written to the database.
	 *
	 * @since 4.4.0
	 *
	 * @param string $domain     The requested domain.
	 * @param string $path       The requested path.
	 * @param string $title      The requested site title.
	 * @param string $user       The user's requested login name.
	 * @param string $user_email The user's email address.
	 * @param string $key        The user's activation key.
	 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	do_action( 'after_signup_site', $domain, $path, $title, $user, $user_email, $key, $meta );
}

/**
 * Record user signup information for future activation.
 *
 * This function is used when user registration is open but
 * new site registration is not.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $user       The user's requested login name.
 * @param string $user_email The user's email address.
 * @param array  $meta       Optional. Signup meta data. Default empty array.
 */
function wpmu_signup_user( $user, $user_email, $meta = array() ) {
	global $wpdb;

	// Format data.
	$user       = preg_replace( '/\s+/', '', sanitize_user( $user, true ) );
	$user_email = sanitize_email( $user_email );
	$key        = substr( md5( time() . wp_rand() . $user_email ), 0, 16 );

	/**
	 * Filters the metadata for a user signup.
	 *
	 * The metadata will be serialized prior to storing it in the database.
	 *
	 * @since 4.8.0
	 *
	 * @param array  $meta       Signup meta data. Default empty array.
	 * @param string $user       The user's requested login name.
	 * @param string $user_email The user's email address.
	 * @param string $key        The user's activation key.
	 */
	$meta = apply_filters( 'signup_user_meta', $meta, $user, $user_email, $key );

	$wpdb->insert(
		$wpdb->signups,
		array(
			'domain'         => '',
			'path'           => '',
			'title'          => '',
			'user_login'     => $user,
			'user_email'     => $user_email,
			'registered'     => current_time( 'mysql', true ),
			'activation_key' => $key,
			'meta'           => serialize( $meta ),
		)
	);

	/**
	 * Fires after a user's signup information has been written to the database.
	 *
	 * @since 4.4.0
	 *
	 * @param string $user       The user's requested login name.
	 * @param string $user_email The user's email address.
	 * @param string $key        The user's activation key.
	 * @param array  $meta       Signup meta data. Default empty array.
	 */
	do_action( 'after_signup_user', $user, $user_email, $key, $meta );
}

/**
 * Send a confirmation request email to a user when they sign up for a new site. The new site will not become active
 * until the confirmation link is clicked.
 *
 * This is the notification function used when site registration
 * is enabled.
 *
 * Filter {@see 'wpmu_signup_blog_notification'} to bypass this function or
 * replace it with your own notification behavior.
 *
 * Filter {@see 'wpmu_signup_blog_notification_email'} and
 * {@see 'wpmu_signup_blog_notification_subject'} to change the content
 * and subject line of the email sent to newly registered users.
 *
 * @since MU (3.0.0)
 *
 * @param string $domain     The new blog domain.
 * @param string $path       The new blog path.
 * @param string $title      The site title.
 * @param string $user_login The user's login name.
 * @param string $user_email The user's email address.
 * @param string $key        The activation key created in wpmu_signup_blog()
 * @param array  $meta       Optional. Signup meta data. By default, contains the requested privacy setting and lang_id.
 * @return bool
 */
function wpmu_signup_blog_notification( $domain, $path, $title, $user_login, $user_email, $key, $meta = array() ) {
	/**
	 * Filters whether to bypass the new site email notification.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string|false $domain     Site domain, or false to prevent the email from sending.
	 * @param string       $path       Site path.
	 * @param string       $title      Site title.
	 * @param string       $user_login User login name.
	 * @param string       $user_email User email address.
	 * @param string       $key        Activation key created in wpmu_signup_blog().
	 * @param array        $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	if ( ! apply_filters( 'wpmu_signup_blog_notification', $domain, $path, $title, $user_login, $user_email, $key, $meta ) ) {
		return false;
	}

	// Send email with activation link.
	if ( ! is_subdomain_install() || get_current_network_id() != 1 ) {
		$activate_url = network_site_url( "wp-activate.php?key=$key" );
	} else {
		$activate_url = "http://{$domain}{$path}wp-activate.php?key=$key"; // @todo Use *_url() API.
	}

	$activate_url = esc_url( $activate_url );

	$admin_email = get_site_option( 'admin_email' );

	if ( '' === $admin_email ) {
		$admin_email = 'support@' . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( '' !== get_site_option( 'site_name' ) ) ? esc_html( get_site_option( 'site_name' ) ) : 'WordPress';
	$message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . 'Content-Type: text/plain; charset="' . get_option( 'blog_charset' ) . "\"\n";

	$user            = get_user_by( 'login', $user_login );
	$switched_locale = switch_to_locale( get_user_locale( $user ) );

	$message = sprintf(
		/**
		 * Filters the message content of the new blog notification email.
		 *
		 * Content should be formatted for transmission via wp_mail().
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $content    Content of the notification email.
		 * @param string $domain     Site domain.
		 * @param string $path       Site path.
		 * @param string $title      Site title.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_blog().
		 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
		 */
		apply_filters(
			'wpmu_signup_blog_notification_email',
			/* translators: New site notification email. 1: Activation URL, 2: New site URL. */
			__( "To activate your blog, please click the following link:\n\n%1\$s\n\nAfter you activate, you will receive *another email* with your login.\n\nAfter you activate, you can visit your site here:\n\n%2\$s" ),
			$domain,
			$path,
			$title,
			$user_login,
			$user_email,
			$key,
			$meta
		),
		$activate_url,
		esc_url( "http://{$domain}{$path}" ),
		$key
	);

	$subject = sprintf(
		/**
		 * Filters the subject of the new blog notification email.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $subject    Subject of the notification email.
		 * @param string $domain     Site domain.
		 * @param string $path       Site path.
		 * @param string $title      Site title.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_blog().
		 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
		 */
		apply_filters(
			'wpmu_signup_blog_notification_subject',
			/* translators: New site notification email subject. 1: Network title, 2: New site URL. */
			_x( '[%1$s] Activate %2$s', 'New site notification email subject' ),
			$domain,
			$path,
			$title,
			$user_login,
			$user_email,
			$key,
			$meta
		),
		$from_name,
		esc_url( 'http://' . $domain . $path )
	);

	wp_mail( $user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Send a confirmation request email to a user when they sign up for a new user account (without signing up for a site
 * at the same time). The user account will not become active until the confirmation link is clicked.
 *
 * This is the notification function used when no new site has
 * been requested.
 *
 * Filter {@see 'wpmu_signup_user_notification'} to bypass this function or
 * replace it with your own notification behavior.
 *
 * Filter {@see 'wpmu_signup_user_notification_email'} and
 * {@see 'wpmu_signup_user_notification_subject'} to change the content
 * and subject line of the email sent to newly registered users.
 *
 * @since MU (3.0.0)
 *
 * @param string $user_login The user's login name.
 * @param string $user_email The user's email address.
 * @param string $key        The activation key created in wpmu_signup_user()
 * @param array  $meta       Optional. Signup meta data. Default empty array.
 * @return bool
 */
function wpmu_signup_user_notification( $user_login, $user_email, $key, $meta = array() ) {
	/**
	 * Filters whether to bypass the email notification for new user sign-up.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $user_login User login name.
	 * @param string $user_email User email address.
	 * @param string $key        Activation key created in wpmu_signup_user().
	 * @param array  $meta       Signup meta data. Default empty array.
	 */
	if ( ! apply_filters( 'wpmu_signup_user_notification', $user_login, $user_email, $key, $meta ) ) {
		return false;
	}

	$user            = get_user_by( 'login', $user_login );
	$switched_locale = switch_to_locale( get_user_locale( $user ) );

	// Send email with activation link.
	$admin_email = get_site_option( 'admin_email' );

	if ( '' === $admin_email ) {
		$admin_email = 'support@' . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( '' !== get_site_option( 'site_name' ) ) ? esc_html( get_site_option( 'site_name' ) ) : 'WordPress';
	$message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . 'Content-Type: text/plain; charset="' . get_option( 'blog_charset' ) . "\"\n";
	$message         = sprintf(
		/**
		 * Filters the content of the notification email for new user sign-up.
		 *
		 * Content should be formatted for transmission via wp_mail().
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $content    Content of the notification email.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_user().
		 * @param array  $meta       Signup meta data. Default empty array.
		 */
		apply_filters(
			'wpmu_signup_user_notification_email',
			/* translators: New user notification email. %s: Activation URL. */
			__( "To activate your user, please click the following link:\n\n%s\n\nAfter you activate, you will receive *another email* with your login." ),
			$user_login,
			$user_email,
			$key,
			$meta
		),
		site_url( "wp-activate.php?key=$key" )
	);

	$subject = sprintf(
		/**
		 * Filters the subject of the notification email of new user signup.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $subject    Subject of the notification email.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_user().
		 * @param array  $meta       Signup meta data. Default empty array.
		 */
		apply_filters(
			'wpmu_signup_user_notification_subject',
			/* translators: New user notification email subject. 1: Network title, 2: New user login. */
			_x( '[%1$s] Activate %2$s', 'New user notification email subject' ),
			$user_login,
			$user_email,
			$key,
			$meta
		),
		$from_name,
		$user_login
	);

	wp_mail( $user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Activate a signup.
 *
 * Hook to {@see 'wpmu_activate_user'} or {@see 'wpmu_activate_blog'} for events
 * that should happen only when users or sites are self-created (since
 * those actions are not called when users and sites are created
 * by a Super Admin).
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $key The activation key provided to the user.
 * @return array|WP_Error An array containing information about the activated user and/or blog
 */
function wpmu_activate_signup( $key ) {
	global $wpdb;

	$signup = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->signups WHERE activation_key = %s", $key ) );

	if ( empty( $signup ) ) {
		return new WP_Error( 'invalid_key', __( 'Invalid activation key.' ) );
	}

	if ( $signup->active ) {
		if ( empty( $signup->domain ) ) {
			return new WP_Error( 'already_active', __( 'The user is already active.' ), $signup );
		} else {
			return new WP_Error( 'already_active', __( 'The site is already active.' ), $signup );
		}
	}

	$meta     = maybe_unserialize( $signup->meta );
	$password = wp_generate_password( 12, false );

	$user_id = username_exists( $signup->user_login );

	if ( ! $user_id ) {
		$user_id = wpmu_create_user( $signup->user_login, $password, $signup->user_email );
	} else {
		$user_already_exists = true;
	}

	if ( ! $user_id ) {
		return new WP_Error( 'create_user', __( 'Could not create user' ), $signup );
	}

	$now = current_time( 'mysql', true );

	if ( empty( $signup->domain ) ) {
		$wpdb->update(
			$wpdb->signups,
			array(
				'active'    => 1,
				'activated' => $now,
			),
			array( 'activation_key' => $key )
		);

		if ( isset( $user_already_exists ) ) {
			return new WP_Error( 'user_already_exists', __( 'That username is already activated.' ), $signup );
		}

		/**
		 * Fires immediately after a new user is activated.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param int    $user_id  User ID.
		 * @param string $password User password.
		 * @param array  $meta     Signup meta data.
		 */
		do_action( 'wpmu_activate_user', $user_id, $password, $meta );

		return array(
			'user_id'  => $user_id,
			'password' => $password,
			'meta'     => $meta,
		);
	}

	$blog_id = wpmu_create_blog( $signup->domain, $signup->path, $signup->title, $user_id, $meta, get_current_network_id() );

	// TODO: What to do if we create a user but cannot create a blog?
	if ( is_wp_error( $blog_id ) ) {
		/*
		 * If blog is taken, that means a previous attempt to activate this blog
		 * failed in between creating the blog and setting the activation flag.
		 * Let's just set the active flag and instruct the user to reset their password.
		 */
		if ( 'blog_taken' === $blog_id->get_error_code() ) {
			$blog_id->add_data( $signup );
			$wpdb->update(
				$wpdb->signups,
				array(
					'active'    => 1,
					'activated' => $now,
				),
				array( 'activation_key' => $key )
			);
		}
		return $blog_id;
	}

	$wpdb->update(
		$wpdb->signups,
		array(
			'active'    => 1,
			'activated' => $now,
		),
		array( 'activation_key' => $key )
	);

	/**
	 * Fires immediately after a site is activated.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int    $blog_id       Blog ID.
	 * @param int    $user_id       User ID.
	 * @param int    $password      User password.
	 * @param string $signup_title  Site title.
	 * @param array  $meta          Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	do_action( 'wpmu_activate_blog', $blog_id, $user_id, $password, $signup->title, $meta );

	return array(
		'blog_id'  => $blog_id,
		'user_id'  => $user_id,
		'password' => $password,
		'title'    => $signup->title,
		'meta'     => $meta,
	);
}

/**
 * Deletes am associated signup entry when a user is deleted from the database.
 *
 * @since 5.5.0
 *
 * @param int      $id       ID of the user to delete.
 * @param int|null $reassign ID of the user to reassign posts and links to.
 * @param WP_User  $user     User object.
 */
function wp_delete_signup_on_user_delete( $id, $reassign, $user ) {
	global $wpdb;

	$wpdb->delete( $wpdb->signups, array( 'user_login' => $user->user_login ) );
}

/**
 * Create a user.
 *
 * This function runs when a user self-registers as well as when
 * a Super Admin creates a new user. Hook to {@see 'wpmu_new_user'} for events
 * that should affect all new users, but only on Multisite (otherwise
 * use {@see'user_register'}).
 *
 * @since MU (3.0.0)
 *
 * @param string $user_name The new user's login name.
 * @param string $password  The new user's password.
 * @param string $email     The new user's email address.
 * @return int|false Returns false on failure, or int $user_id on success
 */
function wpmu_create_user( $user_name, $password, $email ) {
	$user_name = preg_replace( '/\s+/', '', sanitize_user( $user_name, true ) );

	$user_id = wp_create_user( $user_name, $password, $email );
	if ( is_wp_error( $user_id ) ) {
		return false;
	}

	// Newly created users have no roles or caps until they are added to a blog.
	delete_user_option( $user_id, 'capabilities' );
	delete_user_option( $user_id, 'user_level' );

	/**
	 * Fires immediately after a new user is created.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int $user_id User ID.
	 */
	do_action( 'wpmu_new_user', $user_id );

	return $user_id;
}

/**
 * Create a site.
 *
 * This function runs when a user self-registers a new site as well
 * as when a Super Admin creates a new site. Hook to {@see 'wpmu_new_blog'}
 * for events that should affect all new sites.
 *
 * On subdirectory installations, $domain is the same as the main site's
 * domain, and the path is the subdirectory name (eg 'example.com'
 * and '/blog1/'). On subdomain installations, $domain is the new subdomain +
 * root domain (eg 'blog1.example.com'), and $path is '/'.
 *
 * @since MU (3.0.0)
 *
 * @param string $domain     The new site's domain.
 * @param string $path       The new site's path.
 * @param string $title      The new site's title.
 * @param int    $user_id    The user ID of the new site's admin.
 * @param array  $options    Optional. Array of key=>value pairs used to set initial site options.
 *                           If valid status keys are included ('public', 'archived', 'mature',
 *                           'spam', 'deleted', or 'lang_id') the given site status(es) will be
 *                           updated. Otherwise, keys and values will be used to set options for
 *                           the new site. Default empty array.
 * @param int    $network_id Optional. Network ID. Only relevant on multi-network installations.
 * @return int|WP_Error Returns WP_Error object on failure, the new site ID on success.
 */
function wpmu_create_blog( $domain, $path, $title, $user_id, $options = array(), $network_id = 1 ) {
	$defaults = array(
		'public' => 0,
	);
	$options  = wp_parse_args( $options, $defaults );

	$title   = strip_tags( $title );
	$user_id = (int) $user_id;

	// Check if the domain has been used already. We should return an error message.
	if ( domain_exists( $domain, $path, $network_id ) ) {
		return new WP_Error( 'blog_taken', __( 'Sorry, that site already exists!' ) );
	}

	if ( ! wp_installing() ) {
		wp_installing( true );
	}

	$allowed_data_fields = array( 'public', 'archived', 'mature', 'spam', 'deleted', 'lang_id' );

	$site_data = array_merge(
		array(
			'domain'     => $domain,
			'path'       => $path,
			'network_id' => $network_id,
		),
		array_intersect_key( $options, array_flip( $allowed_data_fields ) )
	);

	// Data to pass to wp_initialize_site().
	$site_initialization_data = array(
		'title'   => $title,
		'user_id' => $user_id,
		'options' => array_diff_key( $options, array_flip( $allowed_data_fields ) ),
	);

	$blog_id = wp_insert_site( array_merge( $site_data, $site_initialization_data ) );

	if ( is_wp_error( $blog_id ) ) {
		return $blog_id;
	}

	wp_cache_set( 'last_changed', microtime(), 'sites' );

	return $blog_id;
}

/**
 * Notifies the network admin that a new site has been activated.
 *
 * Filter {@see 'newblog_notify_siteadmin'} to change the content of
 * the notification email.
 *
 * @since MU (3.0.0)
 * @since 5.1.0 $blog_id now supports input from the {@see 'wp_initialize_site'} action.
 *
 * @param WP_Site|int $blog_id    The new site's object or ID.
 * @param string      $deprecated Not used.
 * @return bool
 */
function newblog_notify_siteadmin( $blog_id, $deprecated = '' ) {
	if ( is_object( $blog_id ) ) {
		$blog_id = $blog_id->blog_id;
	}

	if ( 'yes' !== get_site_option( 'registrationnotification' ) ) {
		return false;
	}

	$email = get_site_option( 'admin_email' );

	if ( is_email( $email ) == false ) {
		return false;
	}

	$options_site_url = esc_url( network_admin_url( 'settings.php' ) );

	switch_to_blog( $blog_id );
	$blogname = get_option( 'blogname' );
	$siteurl  = site_url();
	restore_current_blog();

	$msg = sprintf(
		/* translators: New site notification email. 1: Site URL, 2: User IP address, 3: URL to Network Settings screen. */
		__(
			'New Site: %1$s
URL: %2$s
Remote IP address: %3$s

Disable these notifications: %4$s'
		),
		$blogname,
		$siteurl,
		wp_unslash( $_SERVER['REMOTE_ADDR'] ),
		$options_site_url
	);
	/**
	 * Filters the message body of the new site activation email sent
	 * to the network administrator.
	 *
	 * @since MU (3.0.0)
	 * @since 5.4.0 The `$blog_id` parameter was added.
	 *
	 * @param string $msg     Email body.
	 * @param int    $blog_id The new site's ID.
	 */
	$msg = apply_filters( 'newblog_notify_siteadmin', $msg, $blog_id );

	/* translators: New site notification email subject. %s: New site URL. */
	wp_mail( $email, sprintf( __( 'New Site Registration: %s' ), $siteurl ), $msg );

	return true;
}

/**
 * Notifies the network admin that a new user has been activated.
 *
 * Filter {@see 'newuser_notify_siteadmin'} to change the content of
 * the notification email.
 *
 * @since MU (3.0.0)
 *
 * @param int $user_id The new user's ID.
 * @return bool
 */
function newuser_notify_siteadmin( $user_id ) {
	if ( 'yes' !== get_site_option( 'registrationnotification' ) ) {
		return false;
	}

	$email = get_site_option( 'admin_email' );

	if ( is_email( $email ) == false ) {
		return false;
	}

	$user = get_userdata( $user_id );

	$options_site_url = esc_url( network_admin_url( 'settings.php' ) );

	$msg = sprintf(
		/* translators: New user notification email. 1: User login, 2: User IP address, 3: URL to Network Settings screen. */
		__(
			'New User: %1$s
Remote IP address: %2$s

Disable these notifications: %3$s'
		),
		$user->user_login,
		wp_unslash( $_SERVER['REMOTE_ADDR'] ),
		$options_site_url
	);

	/**
	 * Filters the message body of the new user activation email sent
	 * to the network administrator.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string  $msg  Email body.
	 * @param WP_User $user WP_User instance of the new user.
	 */
	$msg = apply_filters( 'newuser_notify_siteadmin', $msg, $user );

	/* translators: New user notification email subject. %s: User login. */
	wp_mail( $email, sprintf( __( 'New User Registration: %s' ), $user->user_login ), $msg );

	return true;
}

/**
 * Checks whether a site name is already taken.
 *
 * The name is the site's subdomain or the site's subdirectory
 * path depending on the network settings.
 *
 * Used during the new site registration process to ensure
 * that each site name is unique.
 *
 * @since MU (3.0.0)
 *
 * @param string $domain     The domain to be checked.
 * @param string $path       The path to be checked.
 * @param int    $network_id Optional. Network ID. Relevant only on multi-network installations.
 * @return int|null The site ID if the site name exists, null otherwise.
 */
function domain_exists( $domain, $path, $network_id = 1 ) {
	$path   = trailingslashit( $path );
	$args   = array(
		'network_id'             => $network_id,
		'domain'                 => $domain,
		'path'                   => $path,
		'fields'                 => 'ids',
		'number'                 => 1,
		'update_site_meta_cache' => false,
	);
	$result = get_sites( $args );
	$result = array_shift( $result );

	/**
	 * Filters whether a site name is taken.
	 *
	 * The name is the site's subdomain or the site's subdirectory
	 * path depending on the network settings.
	 *
	 * @since 3.5.0
	 *
	 * @param int|null $result     The site ID if the site name exists, null otherwise.
	 * @param string   $domain     Domain to be checked.
	 * @param string   $path       Path to be checked.
	 * @param int      $network_id Network ID. Relevant only on multi-network installations.
	 */
	return apply_filters( 'domain_exists', $result, $domain, $path, $network_id );
}

/**
 * Notifies the site administrator that their site activation was successful.
 *
 * Filter {@see 'wpmu_welcome_notification'} to disable or bypass.
 *
 * Filter {@see 'update_welcome_email'} and {@see 'update_welcome_subject'} to
 * modify the content and subject line of the notification email.
 *
 * @since MU (3.0.0)
 *
 * @param int    $blog_id  Site ID.
 * @param int    $user_id  User ID.
 * @param string $password User password, or "N/A" if the user account is not new.
 * @param string $title    Site title.
 * @param array  $meta     Optional. Signup meta data. By default, contains the requested privacy setting and lang_id.
 * @return bool Whether the email notification was sent.
 */
function wpmu_welcome_notification( $blog_id, $user_id, $password, $title, $meta = array() ) {
	$current_network = get_network();

	/**
	 * Filters whether to bypass the welcome email sent to the site administrator after site activation.
	 *
	 * Returning false disables the welcome email.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int|false $blog_id  Site ID, or false to prevent the email from sending.
	 * @param int       $user_id  User ID of the site administrator.
	 * @param string    $password User password, or "N/A" if the user account is not new.
	 * @param string    $title    Site title.
	 * @param array     $meta     Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	if ( ! apply_filters( 'wpmu_welcome_notification', $blog_id, $user_id, $password, $title, $meta ) ) {
		return false;
	}

	$user = get_userdata( $user_id );

	$switched_locale = switch_to_locale( get_user_locale( $user ) );

	$welcome_email = get_site_option( 'welcome_email' );
	if ( false == $welcome_email ) {
		/* translators: Do not translate USERNAME, SITE_NAME, BLOG_URL, PASSWORD: those are placeholders. */
		$welcome_email = __(
			'Howdy USERNAME,

Your new SITE_NAME site has been successfully set up at:
BLOG_URL

You can log in to the administrator account with the following information:

Username: USERNAME
Password: PASSWORD
Log in here: BLOG_URLwp-login.php

We hope you enjoy your new site. Thanks!

--The Team @ SITE_NAME'
		);
	}

	$url = get_blogaddress_by_id( $blog_id );

	$welcome_email = str_replace( 'SITE_NAME', $current_network->site_name, $welcome_email );
	$welcome_email = str_replace( 'BLOG_TITLE', $title, $welcome_email );
	$welcome_email = str_replace( 'BLOG_URL', $url, $welcome_email );
	$welcome_email = str_replace( 'USERNAME', $user->user_login, $welcome_email );
	$welcome_email = str_replace( 'PASSWORD', $password, $welcome_email );

	/**
	 * Filters the content of the welcome email sent to the site administrator after site activation.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $welcome_email Message body of the email.
	 * @param int    $blog_id       Site ID.
	 * @param int    $user_id       User ID of the site administrator.
	 * @param string $password      User password, or "N/A" if the user account is not new.
	 * @param string $title         Site title.
	 * @param array  $meta          Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	$welcome_email = apply_filters( 'update_welcome_email', $welcome_email, $blog_id, $user_id, $password, $title, $meta );

	$admin_email = get_site_option( 'admin_email' );

	if ( '' === $admin_email ) {
		$admin_email = 'support@' . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( '' !== get_site_option( 'site_name' ) ) ? esc_html( get_site_option( 'site_name' ) ) : 'WordPress';
	$message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . 'Content-Type: text/plain; charset="' . get_option( 'blog_charset' ) . "\"\n";
	$message         = $welcome_email;

	if ( empty( $current_network->site_name ) ) {
		$current_network->site_name = 'WordPress';
	}

	/* translators: New site notification email subject. 1: Network title, 2: New site title. */
	$subject = __( 'New %1$s Site: %2$s' );

	/**
	 * Filters the subject of the welcome email sent to the site administrator after site activation.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $subject Subject of the email.
	 */
	$subject = apply_filters( 'update_welcome_subject', sprintf( $subject, $current_network->site_name, wp_unslash( $title ) ) );

	wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Notifies the Multisite network administrator that a new site was created.
 *
 * Filter {@see 'send_new_site_email'} to disable or bypass.
 *
 * Filter {@see 'new_site_email'} to filter the contents.
 *
 * @since 5.6.0
 *
 * @param int $site_id Site ID of the new site.
 * @param int $user_id User ID of the administrator of the new site.
 * @return bool Whether the email notification was sent.
 */
function wpmu_new_site_admin_notification( $site_id, $user_id ) {
	$site  = get_site( $site_id );
	$user  = get_userdata( $user_id );
	$email = get_site_option( 'admin_email' );

	if ( ! $site || ! $user || ! $email ) {
		return false;
	}

	/**
	 * Filters whether to send an email to the Multisite network administrator when a new site is created.
	 *
	 * Return false to disable sending the email.
	 *
	 * @since 5.6.0
	 *
	 * @param bool    $send Whether to send the email.
	 * @param WP_Site $site Site object of the new site.
	 * @param WP_User $user User object of the administrator of the new site.
	 */
	if ( ! apply_filters( 'send_new_site_email', true, $site, $user ) ) {
		return false;
	}

	$switched_locale = false;
	$network_admin   = get_user_by( 'email', $email );

	if ( $network_admin ) {
		// If the network admin email address corresponds to a user, switch to their locale.
		$switched_locale = switch_to_locale( get_user_locale( $network_admin ) );
	} else {
		// Otherwise switch to the locale of the current site.
		$switched_locale = switch_to_locale( get_locale() );
	}

	$subject = sprintf(
		/* translators: New site notification email subject. %s: Network title. */
		__( '[%s] New Site Created' ),
		get_network()->site_name
	);

	$message = sprintf(
		/* translators: New site notification email. 1: User login, 2: Site URL, 3: Site title. */
		__(
			'New site created by %1$s

Address: %2$s
Name: %3$s'
		),
		$user->user_login,
		get_site_url( $site->id ),
		get_blog_option( $site->id, 'blogname' )
	);

	$header = sprintf(
		'From: "%1$s" <%2$s>',
		_x( 'Site Admin', 'email "From" field' ),
		$email
	);

	$new_site_email = array(
		'to'      => $email,
		'subject' => $subject,
		'message' => $message,
		'headers' => $header,
	);

	/**
	 * Filters the content of the email sent to the Multisite network administrator when a new site is created.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since 5.6.0
	 *
	 * @param array $new_site_email {
	 *     Used to build wp_mail().
	 *
	 *     @type string $to      The email address of the recipient.
	 *     @type string $subject The subject of the email.
	 *     @type string $message The content of the email.
	 *     @type string $headers Headers.
	 * }
	 * @param WP_Site $site         Site object of the new site.
	 * @param WP_User $user         User object of the administrator of the new site.
	 */
	$new_site_email = apply_filters( 'new_site_email', $new_site_email, $site, $user );

	wp_mail(
		$new_site_email['to'],
		wp_specialchars_decode( $new_site_email['subject'] ),
		$new_site_email['message'],
		$new_site_email['headers']
	);

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Notify a user that their account activation has been successful.
 *
 * Filter {@see 'wpmu_welcome_user_notification'} to disable or bypass.
 *
 * Filter {@see 'update_welcome_user_email'} and {@see 'update_welcome_user_subject'} to
 * modify the content and subject line of the notification email.
 *
 * @since MU (3.0.0)
 *
 * @param int    $user_id  User ID.
 * @param string $password User password.
 * @param array  $meta     Optional. Signup meta data. Default empty array.
 * @return bool
 */
function wpmu_welcome_user_notification( $user_id, $password, $meta = array() ) {
	$current_network = get_network();

	/**
	 * Filters whether to bypass the welcome email after user activation.
	 *
	 * Returning false disables the welcome email.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int    $user_id  User ID.
	 * @param string $password User password.
	 * @param array  $meta     Signup meta data. Default empty array.
	 */
	if ( ! apply_filters( 'wpmu_welcome_user_notification', $user_id, $password, $meta ) ) {
		return false;
	}

	$welcome_email = get_site_option( 'welcome_user_email' );

	$user = get_userdata( $user_id );

	$switched_locale = switch_to_locale( get_user_locale( $user ) );

	/**
	 * Filters the content of the welcome email after user activation.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $welcome_email The message body of the account activation success email.
	 * @param int    $user_id       User ID.
	 * @param string $password      User password.
	 * @param array  $meta          Signup meta data. Default empty array.
	 */
	$welcome_email = apply_filters( 'update_welcome_user_email', $welcome_email, $user_id, $password, $meta );
	$welcome_email = str_replace( 'SITE_NAME', $current_network->site_name, $welcome_email );
	$welcome_email = str_replace( 'USERNAME', $user->user_login, $welcome_email );
	$welcome_email = str_replace( 'PASSWORD', $password, $welcome_email );
	$welcome_email = str_replace( 'LOGINLINK', wp_login_url(), $welcome_email );

	$admin_email = get_site_option( 'admin_email' );

	if ( '' === $admin_email ) {
		$admin_email = 'support@' . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( '' !== get_site_option( 'site_name' ) ) ? esc_html( get_site_option( 'site_name' ) ) : 'WordPress';
	$message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . 'Content-Type: text/plain; charset="' . get_option( 'blog_charset' ) . "\"\n";
	$message         = $welcome_email;

	if ( empty( $current_network->site_name ) ) {
		$current_network->site_name = 'WordPress';
	}

	/* translators: New user notification email subject. 1: Network title, 2: New user login. */
	$subject = __( 'New %1$s User: %2$s' );

	/**
	 * Filters the subject of the welcome email after user activation.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $subject Subject of the email.
	 */
	$subject = apply_filters( 'update_welcome_user_subject', sprintf( $subject, $current_network->site_name, $user->user_login ) );

	wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Get the current network.
 *
 * Returns an object containing the 'id', 'domain', 'path', and 'site_name'
 * properties of the network being viewed.
 *
 * @see wpmu_current_site()
 *
 * @since MU (3.0.0)
 *
 * @global WP_Network $current_site
 *
 * @return WP_Network
 */
function get_current_site() {
	global $current_site;
	return $current_site;
}

/**
 * Get a user's most recent post.
 *
 * Walks through each of a user's blogs to find the post with
 * the most recent post_date_gmt.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $user_id
 * @return array Contains the blog_id, post_id, post_date_gmt, and post_gmt_ts
 */
function get_most_recent_post_of_user( $user_id ) {
	global $wpdb;

	$user_blogs       = get_blogs_of_user( (int) $user_id );
	$most_recent_post = array();

	// Walk through each blog and get the most recent post
	// published by $user_id.
	foreach ( (array) $user_blogs as $blog ) {
		$prefix      = $wpdb->get_blog_prefix( $blog->userblog_id );
		$recent_post = $wpdb->get_row( $wpdb->prepare( "SELECT ID, post_date_gmt FROM {$prefix}posts WHERE post_author = %d AND post_type = 'post' AND post_status = 'publish' ORDER BY post_date_gmt DESC LIMIT 1", $user_id ), ARRAY_A );

		// Make sure we found a post.
		if ( isset( $recent_post['ID'] ) ) {
			$post_gmt_ts = strtotime( $recent_post['post_date_gmt'] );

			/*
			 * If this is the first post checked
			 * or if this post is newer than the current recent post,
			 * make it the new most recent post.
			 */
			if ( ! isset( $most_recent_post['post_gmt_ts'] ) || ( $post_gmt_ts > $most_recent_post['post_gmt_ts'] ) ) {
				$most_recent_post = array(
					'blog_id'       => $blog->userblog_id,
					'post_id'       => $recent_post['ID'],
					'post_date_gmt' => $recent_post['post_date_gmt'],
					'post_gmt_ts'   => $post_gmt_ts,
				);
			}
		}
	}

	return $most_recent_post;
}

//
// Misc functions.
//

/**
 * Check an array of MIME types against a list of allowed types.
 *
 * WordPress ships with a set of allowed upload filetypes,
 * which is defined in wp-includes/functions.php in
 * get_allowed_mime_types(). This function is used to filter
 * that list against the filetypes allowed provided by Multisite
 * Super Admins at wp-admin/network/settings.php.
 *
 * @since MU (3.0.0)
 *
 * @param array $mimes
 * @return array
 */
function check_upload_mimes( $mimes ) {
	$site_exts  = explode( ' ', get_site_option( 'upload_filetypes', 'jpg jpeg png gif' ) );
	$site_mimes = array();
	foreach ( $site_exts as $ext ) {
		foreach ( $mimes as $ext_pattern => $mime ) {
			if ( '' !== $ext && false !== strpos( $ext_pattern, $ext ) ) {
				$site_mimes[ $ext_pattern ] = $mime;
			}
		}
	}
	return $site_mimes;
}

/**
 * Update a blog's post count.
 *
 * WordPress MS stores a blog's post count as an option so as
 * to avoid extraneous COUNTs when a blog's details are fetched
 * with get_site(). This function is called when posts are published
 * or unpublished to make sure the count stays current.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $deprecated Not used.
 */
function update_posts_count( $deprecated = '' ) {
	global $wpdb;
	update_option( 'post_count', (int) $wpdb->get_var( "SELECT COUNT(ID) FROM {$wpdb->posts} WHERE post_status = 'publish' and post_type = 'post'" ) );
}

/**
 * Logs the user email, IP, and registration date of a new site.
 *
 * @since MU (3.0.0)
 * @since 5.1.0 Parameters now support input from the {@see 'wp_initialize_site'} action.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param WP_Site|int $blog_id The new site's object or ID.
 * @param int|array   $user_id User ID, or array of arguments including 'user_id'.
 */
function wpmu_log_new_registrations( $blog_id, $user_id ) {
	global $wpdb;

	if ( is_object( $blog_id ) ) {
		$blog_id = $blog_id->blog_id;
	}

	if ( is_array( $user_id ) ) {
		$user_id = ! empty( $user_id['user_id'] ) ? $user_id['user_id'] : 0;
	}

	$user = get_userdata( (int) $user_id );
	if ( $user ) {
		$wpdb->insert(
			$wpdb->registration_log,
			array(
				'email'           => $user->user_email,
				'IP'              => preg_replace( '/[^0-9., ]/', '', wp_unslash( $_SERVER['REMOTE_ADDR'] ) ),
				'blog_id'         => $blog_id,
				'date_registered' => current_time( 'mysql' ),
			)
		);
	}
}

/**
 * Maintains a canonical list of terms by syncing terms created for each blog with the global terms table.
 *
 * @since 3.0.0
 *
 * @see term_id_filter
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int    $term_id    An ID for a term on the current blog.
 * @param string $deprecated Not used.
 * @return int An ID from the global terms table mapped from $term_id.
 */
function global_terms( $term_id, $deprecated = '' ) {
	global $wpdb;
	static $global_terms_recurse = null;

	if ( ! global_terms_enabled() ) {
		return $term_id;
	}

	// Prevent a race condition.
	$recurse_start = false;
	if ( null === $global_terms_recurse ) {
		$recurse_start        = true;
		$global_terms_recurse = 1;
	} elseif ( 10 < $global_terms_recurse++ ) {
		return $term_id;
	}

	$term_id = (int) $term_id;
	$c       = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->terms WHERE term_id = %d", $term_id ) );

	$global_id = $wpdb->get_var( $wpdb->prepare( "SELECT cat_ID FROM $wpdb->sitecategories WHERE category_nicename = %s", $c->slug ) );
	if ( null == $global_id ) {
		$used_global_id = $wpdb->get_var( $wpdb->prepare( "SELECT cat_ID FROM $wpdb->sitecategories WHERE cat_ID = %d", $c->term_id ) );
		if ( null == $used_global_id ) {
			$wpdb->insert(
				$wpdb->sitecategories,
				array(
					'cat_ID'            => $term_id,
					'cat_name'          => $c->name,
					'category_nicename' => $c->slug,
				)
			);
			$global_id = $wpdb->insert_id;
			if ( empty( $global_id ) ) {
				return $term_id;
			}
		} else {
			$max_global_id = $wpdb->get_var( "SELECT MAX(cat_ID) FROM $wpdb->sitecategories" );
			$max_local_id  = $wpdb->get_var( "SELECT MAX(term_id) FROM $wpdb->terms" );
			$new_global_id = max( $max_global_id, $max_local_id ) + mt_rand( 100, 400 );
			$wpdb->insert(
				$wpdb->sitecategories,
				array(
					'cat_ID'            => $new_global_id,
					'cat_name'          => $c->name,
					'category_nicename' => $c->slug,
				)
			);
			$global_id = $wpdb->insert_id;
		}
	} elseif ( $global_id != $term_id ) {
		$local_id = $wpdb->get_var( $wpdb->prepare( "SELECT term_id FROM $wpdb->terms WHERE term_id = %d", $global_id ) );
		if ( null != $local_id ) {
			global_terms( $local_id );
			if ( 10 < $global_terms_recurse ) {
				$global_id = $term_id;
			}
		}
	}

	if ( $global_id != $term_id ) {
		if ( get_option( 'default_category' ) == $term_id ) {
			update_option( 'default_category', $global_id );
		}

		$wpdb->update( $wpdb->terms, array( 'term_id' => $global_id ), array( 'term_id' => $term_id ) );
		$wpdb->update( $wpdb->term_taxonomy, array( 'term_id' => $global_id ), array( 'term_id' => $term_id ) );
		$wpdb->update( $wpdb->term_taxonomy, array( 'parent' => $global_id ), array( 'parent' => $term_id ) );

		clean_term_cache( $term_id );
	}
	if ( $recurse_start ) {
		$global_terms_recurse = null;
	}

	return $global_id;
}

/**
 * Ensure that the current site's domain is listed in the allowed redirect host list.
 *
 * @see wp_validate_redirect()
 * @since MU (3.0.0)
 *
 * @param array|string $deprecated Not used.
 * @return string[] {
 *     An array containing the current site's domain.
 *
 *     @type string $0 The current site's domain.
 * }
 */
function redirect_this_site( $deprecated = '' ) {
	return array( get_network()->domain );
}

/**
 * Check whether an upload is too big.
 *
 * @since MU (3.0.0)
 *
 * @blessed
 *
 * @param array $upload
 * @return string|array If the upload is under the size limit, $upload is returned. Otherwise returns an error message.
 */
function upload_is_file_too_big( $upload ) {
	if ( ! is_array( $upload ) || defined( 'WP_IMPORTING' ) || get_site_option( 'upload_space_check_disabled' ) ) {
		return $upload;
	}

	if ( strlen( $upload['bits'] ) > ( KB_IN_BYTES * get_site_option( 'fileupload_maxk', 1500 ) ) ) {
		/* translators: %s: Maximum allowed file size in kilobytes. */
		return sprintf( __( 'This file is too big. Files must be less than %s KB in size.' ) . '<br />', get_site_option( 'fileupload_maxk', 1500 ) );
	}

	return $upload;
}

/**
 * Add a nonce field to the signup page.
 *
 * @since MU (3.0.0)
 */
function signup_nonce_fields() {
	$id = mt_rand();
	echo "<input type='hidden' name='signup_form_id' value='{$id}' />";
	wp_nonce_field( 'signup_form_' . $id, '_signup_form', false );
}

/**
 * Process the signup nonce created in signup_nonce_fields().
 *
 * @since MU (3.0.0)
 *
 * @param array $result
 * @return array
 */
function signup_nonce_check( $result ) {
	if ( ! strpos( $_SERVER['PHP_SELF'], 'wp-signup.php' ) ) {
		return $result;
	}

	if ( ! wp_verify_nonce( $_POST['_signup_form'], 'signup_form_' . $_POST['signup_form_id'] ) ) {
		$result['errors']->add( 'invalid_nonce', __( 'Unable to submit this form, please try again.' ) );
	}

	return $result;
}

/**
 * Correct 404 redirects when NOBLOGREDIRECT is defined.
 *
 * @since MU (3.0.0)
 */
function maybe_redirect_404() {
	if ( is_main_site() && is_404() && defined( 'NOBLOGREDIRECT' ) ) {
		/**
		 * Filters the redirect URL for 404s on the main site.
		 *
		 * The filter is only evaluated if the NOBLOGREDIRECT constant is defined.
		 *
		 * @since 3.0.0
		 *
		 * @param string $no_blog_redirect The redirect URL defined in NOBLOGREDIRECT.
		 */
		$destination = apply_filters( 'blog_redirect_404', NOBLOGREDIRECT );

		if ( $destination ) {
			if ( '%siteurl%' === $destination ) {
				$destination = network_home_url();
			}

			wp_redirect( $destination );
			exit;
		}
	}
}

/**
 * Add a new user to a blog by visiting /newbloguser/{key}/.
 *
 * This will only work when the user's details are saved as an option
 * keyed as 'new_user_{key}', where '{key}' is a hash generated for the user to be
 * added, as when a user is invited through the regular WP Add User interface.
 *
 * @since MU (3.0.0)
 */
function maybe_add_existing_user_to_blog() {
	if ( false === strpos( $_SERVER['REQUEST_URI'], '/newbloguser/' ) ) {
		return;
	}

	$parts = explode( '/', $_SERVER['REQUEST_URI'] );
	$key   = array_pop( $parts );

	if ( '' === $key ) {
		$key = array_pop( $parts );
	}

	$details = get_option( 'new_user_' . $key );
	if ( ! empty( $details ) ) {
		delete_option( 'new_user_' . $key );
	}

	if ( empty( $details ) || is_wp_error( add_existing_user_to_blog( $details ) ) ) {
		wp_die(
			sprintf(
				/* translators: %s: Home URL. */
				__( 'An error occurred adding you to this site. Go to the <a href="%s">homepage</a>.' ),
				home_url()
			)
		);
	}

	wp_die(
		sprintf(
			/* translators: 1: Home URL, 2: Admin URL. */
			__( 'You have been added to this site. Please visit the <a href="%1$s">homepage</a> or <a href="%2$s">log in</a> using your username and password.' ),
			home_url(),
			admin_url()
		),
		__( 'WordPress &rsaquo; Success' ),
		array( 'response' => 200 )
	);
}

/**
 * Add a user to a blog based on details from maybe_add_existing_user_to_blog().
 *
 * @since MU (3.0.0)
 *
 * @param array|false $details {
 *     User details. Must at least contain values for the keys listed below.
 *
 *     @type int    $user_id The ID of the user being added to the current blog.
 *     @type string $role    The role to be assigned to the user.
 * }
 * @return true|WP_Error|void True on success or a WP_Error object if the user doesn't exist
 *                            or could not be added. Void if $details array was not provided.
 */
function add_existing_user_to_blog( $details = false ) {
	if ( is_array( $details ) ) {
		$blog_id = get_current_blog_id();
		$result  = add_user_to_blog( $blog_id, $details['user_id'], $details['role'] );

		/**
		 * Fires immediately after an existing user is added to a site.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param int           $user_id User ID.
		 * @param true|WP_Error $result  True on success or a WP_Error object if the user doesn't exist
		 *                               or could not be added.
		 */
		do_action( 'added_existing_user', $details['user_id'], $result );

		return $result;
	}
}

/**
 * Adds a newly created user to the appropriate blog
 *
 * To add a user in general, use add_user_to_blog(). This function
 * is specifically hooked into the {@see 'wpmu_activate_user'} action.
 *
 * @since MU (3.0.0)
 *
 * @see add_user_to_blog()
 *
 * @param int    $user_id  User ID.
 * @param string $password User password. Ignored.
 * @param array  $meta     Signup meta data.
 */
function add_new_user_to_blog( $user_id, $password, $meta ) {
	if ( ! empty( $meta['add_to_blog'] ) ) {
		$blog_id = $meta['add_to_blog'];
		$role    = $meta['new_role'];
		remove_user_from_blog( $user_id, get_network()->site_id ); // Remove user from main blog.

		$result = add_user_to_blog( $blog_id, $user_id, $role );

		if ( ! is_wp_error( $result ) ) {
			update_user_meta( $user_id, 'primary_blog', $blog_id );
		}
	}
}

/**
 * Correct From host on outgoing mail to match the site domain
 *
 * @since MU (3.0.0)
 *
 * @param PHPMailer $phpmailer The PHPMailer instance (passed by reference).
 */
function fix_phpmailer_messageid( $phpmailer ) {
	$phpmailer->Hostname = get_network()->domain;
}

/**
 * Check to see whether a user is marked as a spammer, based on user login.
 *
 * @since MU (3.0.0)
 *
 * @param string|WP_User $user Optional. Defaults to current user. WP_User object,
 *                             or user login name as a string.
 * @return bool
 */
function is_user_spammy( $user = null ) {
	if ( ! ( $user instanceof WP_User ) ) {
		if ( $user ) {
			$user = get_user_by( 'login', $user );
		} else {
			$user = wp_get_current_user();
		}
	}

	return $user && isset( $user->spam ) && 1 == $user->spam;
}

/**
 * Update this blog's 'public' setting in the global blogs table.
 *
 * Public blogs have a setting of 1, private blogs are 0.
 *
 * @since MU (3.0.0)
 *
 * @param int $old_value
 * @param int $value     The new public value
 */
function update_blog_public( $old_value, $value ) {
	update_blog_status( get_current_blog_id(), 'public', (int) $value );
}

/**
 * Check whether users can self-register, based on Network settings.
 *
 * @since MU (3.0.0)
 *
 * @return bool
 */
function users_can_register_signup_filter() {
	$registration = get_site_option( 'registration' );
	return ( 'all' === $registration || 'user' === $registration );
}

/**
 * Ensure that the welcome message is not empty. Currently unused.
 *
 * @since MU (3.0.0)
 *
 * @param string $text
 * @return string
 */
function welcome_user_msg_filter( $text ) {
	if ( ! $text ) {
		remove_filter( 'site_option_welcome_user_email', 'welcome_user_msg_filter' );

		/* translators: Do not translate USERNAME, PASSWORD, LOGINLINK, SITE_NAME: those are placeholders. */
		$text = __(
			'Howdy USERNAME,

Your new account is set up.

You can log in with the following information:
Username: USERNAME
Password: PASSWORD
LOGINLINK

Thanks!

--The Team @ SITE_NAME'
		);
		update_site_option( 'welcome_user_email', $text );
	}
	return $text;
}

/**
 * Whether to force SSL on content.
 *
 * @since 2.8.5
 *
 * @param bool $force
 * @return bool True if forced, false if not forced.
 */
function force_ssl_content( $force = '' ) {
	static $forced_content = false;

	if ( ! $force ) {
		$old_forced     = $forced_content;
		$forced_content = $force;
		return $old_forced;
	}

	return $forced_content;
}

/**
 * Formats a URL to use https.
 *
 * Useful as a filter.
 *
 * @since 2.8.5
 *
 * @param string $url URL
 * @return string URL with https as the scheme
 */
function filter_SSL( $url ) {  // phpcs:ignore WordPress.NamingConventions.ValidFunctionName.FunctionNameInvalid
	if ( ! is_string( $url ) ) {
		return get_bloginfo( 'url' ); // Return home blog URL with proper scheme.
	}

	if ( force_ssl_content() && is_ssl() ) {
		$url = set_url_scheme( $url, 'https' );
	}

	return $url;
}

/**
 * Schedule update of the network-wide counts for the current network.
 *
 * @since 3.1.0
 */
function wp_schedule_update_network_counts() {
	if ( ! is_main_site() ) {
		return;
	}

	if ( ! wp_next_scheduled( 'update_network_counts' ) && ! wp_installing() ) {
		wp_schedule_event( time(), 'twicedaily', 'update_network_counts' );
	}
}

/**
 * Update the network-wide counts for the current network.
 *
 * @since 3.1.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_counts( $network_id = null ) {
	wp_update_network_user_counts( $network_id );
	wp_update_network_site_counts( $network_id );
}

/**
 * Update the count of sites for the current network.
 *
 * If enabled through the {@see 'enable_live_network_counts'} filter, update the sites count
 * on a network when a site is created or its status is updated.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_maybe_update_network_site_counts( $network_id = null ) {
	$is_small_network = ! wp_is_large_network( 'sites', $network_id );

	/**
	 * Filters whether to update network site or user counts when a new site is created.
	 *
	 * @since 3.7.0
	 *
	 * @see wp_is_large_network()
	 *
	 * @param bool   $small_network Whether the network is considered small.
	 * @param string $context       Context. Either 'users' or 'sites'.
	 */
	if ( ! apply_filters( 'enable_live_network_counts', $is_small_network, 'sites' ) ) {
		return;
	}

	wp_update_network_site_counts( $network_id );
}

/**
 * Update the network-wide users count.
 *
 * If enabled through the {@see 'enable_live_network_counts'} filter, update the users count
 * on a network when a user is created or its status is updated.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_maybe_update_network_user_counts( $network_id = null ) {
	$is_small_network = ! wp_is_large_network( 'users', $network_id );

	/** This filter is documented in wp-includes/ms-functions.php */
	if ( ! apply_filters( 'enable_live_network_counts', $is_small_network, 'users' ) ) {
		return;
	}

	wp_update_network_user_counts( $network_id );
}

/**
 * Update the network-wide site count.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_site_counts( $network_id = null ) {
	$network_id = (int) $network_id;
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	$count = get_sites(
		array(
			'network_id'             => $network_id,
			'spam'                   => 0,
			'deleted'                => 0,
			'archived'               => 0,
			'count'                  => true,
			'update_site_meta_cache' => false,
		)
	);

	update_network_option( $network_id, 'blog_count', $count );
}

/**
 * Update the network-wide user count.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_user_counts( $network_id = null ) {
	global $wpdb;

	$count = $wpdb->get_var( "SELECT COUNT(ID) as c FROM $wpdb->users WHERE spam = '0' AND deleted = '0'" );
	update_network_option( $network_id, 'user_count', $count );
}

/**
 * Returns the space used by the current site.
 *
 * @since 3.5.0
 *
 * @return int Used space in megabytes.
 */
function get_space_used() {
	/**
	 * Filters the amount of storage space used by the current site, in megabytes.
	 *
	 * @since 3.5.0
	 *
	 * @param int|false $space_used The amount of used space, in megabytes. Default false.
	 */
	$space_used = apply_filters( 'pre_get_space_used', false );

	if ( false === $space_used ) {
		$upload_dir = wp_upload_dir();
		$space_used = get_dirsize( $upload_dir['basedir'] ) / MB_IN_BYTES;
	}

	return $space_used;
}

/**
 * Returns the upload quota for the current blog.
 *
 * @since MU (3.0.0)
 *
 * @return int Quota in megabytes
 */
function get_space_allowed() {
	$space_allowed = get_option( 'blog_upload_space' );

	if ( ! is_numeric( $space_allowed ) ) {
		$space_allowed = get_site_option( 'blog_upload_space' );
	}

	if ( ! is_numeric( $space_allowed ) ) {
		$space_allowed = 100;
	}

	/**
	 * Filters the upload quota for the current site.
	 *
	 * @since 3.7.0
	 *
	 * @param int $space_allowed Upload quota in megabytes for the current blog.
	 */
	return apply_filters( 'get_space_allowed', $space_allowed );
}

/**
 * Determines if there is any upload space left in the current blog's quota.
 *
 * @since 3.0.0
 *
 * @return int of upload space available in bytes
 */
function get_upload_space_available() {
	$allowed = get_space_allowed();
	if ( $allowed < 0 ) {
		$allowed = 0;
	}
	$space_allowed = $allowed * MB_IN_BYTES;
	if ( get_site_option( 'upload_space_check_disabled' ) ) {
		return $space_allowed;
	}

	$space_used = get_space_used() * MB_IN_BYTES;

	if ( ( $space_allowed - $space_used ) <= 0 ) {
		return 0;
	}

	return $space_allowed - $space_used;
}

/**
 * Determines if there is any upload space left in the current blog's quota.
 *
 * @since 3.0.0
 * @return bool True if space is available, false otherwise.
 */
function is_upload_space_available() {
	if ( get_site_option( 'upload_space_check_disabled' ) ) {
		return true;
	}

	return (bool) get_upload_space_available();
}

/**
 * Filters the maximum upload file size allowed, in bytes.
 *
 * @since 3.0.0
 *
 * @param int $size Upload size limit in bytes.
 * @return int Upload size limit in bytes.
 */
function upload_size_limit_filter( $size ) {
	$fileupload_maxk = KB_IN_BYTES * get_site_option( 'fileupload_maxk', 1500 );
	if ( get_site_option( 'upload_space_check_disabled' ) ) {
		return min( $size, $fileupload_maxk );
	}

	return min( $size, $fileupload_maxk, get_upload_space_available() );
}

/**
 * Whether or not we have a large network.
 *
 * The default criteria for a large network is either more than 10,000 users or more than 10,000 sites.
 * Plugins can alter this criteria using the {@see 'wp_is_large_network'} filter.
 *
 * @since 3.3.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param string   $using      'sites or 'users'. Default is 'sites'.
 * @param int|null $network_id ID of the network. Default is the current network.
 * @return bool True if the network meets the criteria for large. False otherwise.
 */
function wp_is_large_network( $using = 'sites', $network_id = null ) {
	$network_id = (int) $network_id;
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	if ( 'users' === $using ) {
		$count = get_user_count( $network_id );
		/**
		 * Filters whether the network is considered large.
		 *
		 * @since 3.3.0
		 * @since 4.8.0 The `$network_id` parameter has been added.
		 *
		 * @param bool   $is_large_network Whether the network has more than 10000 users or sites.
		 * @param string $component        The component to count. Accepts 'users', or 'sites'.
		 * @param int    $count            The count of items for the component.
		 * @param int    $network_id       The ID of the network being checked.
		 */
		return apply_filters( 'wp_is_large_network', $count > 10000, 'users', $count, $network_id );
	}

	$count = get_blog_count( $network_id );

	/** This filter is documented in wp-includes/ms-functions.php */
	return apply_filters( 'wp_is_large_network', $count > 10000, 'sites', $count, $network_id );
}

/**
 * Retrieves a list of reserved site on a sub-directory Multisite installation.
 *
 * @since 4.4.0
 *
 * @return string[] Array of reserved names.
 */
function get_subdirectory_reserved_names() {
	$names = array(
		'page',
		'comments',
		'blog',
		'files',
		'feed',
		'wp-admin',
		'wp-content',
		'wp-includes',
		'wp-json',
		'embed',
	);

	/**
	 * Filters reserved site names on a sub-directory Multisite installation.
	 *
	 * @since 3.0.0
	 * @since 4.4.0 'wp-admin', 'wp-content', 'wp-includes', 'wp-json', and 'embed' were added
	 *              to the reserved names list.
	 *
	 * @param string[] $subdirectory_reserved_names Array of reserved names.
	 */
	return apply_filters( 'subdirectory_reserved_names', $names );
}

/**
 * Send a confirmation request email when a change of network admin email address is attempted.
 *
 * The new network admin address will not become active until confirmed.
 *
 * @since 4.9.0
 *
 * @param string $old_value The old network admin email address.
 * @param string $value     The proposed new network admin email address.
 */
function update_network_option_new_admin_email( $old_value, $value ) {
	if ( get_site_option( 'admin_email' ) === $value || ! is_email( $value ) ) {
		return;
	}

	$hash            = md5( $value . time() . mt_rand() );
	$new_admin_email = array(
		'hash'     => $hash,
		'newemail' => $value,
	);
	update_site_option( 'network_admin_hash', $new_admin_email );

	$switched_locale = switch_to_locale( get_user_locale() );

	/* translators: Do not translate USERNAME, ADMIN_URL, EMAIL, SITENAME, SITEURL: those are placeholders. */
	$email_text = __(
		'Howdy ###USERNAME###,

You recently requested to have the network admin email address on
your network changed.

If this is correct, please click on the following link to change it:
###ADMIN_URL###

You can safely ignore and delete this email if you do not want to
take this action.

This email has been sent to ###EMAIL###

Regards,
All at ###SITENAME###
###SITEURL###'
	);

	/**
	 * Filters the text of the email sent when a change of network admin email address is attempted.
	 *
	 * The following strings have a special meaning and will get replaced dynamically:
	 * ###USERNAME###  The current user's username.
	 * ###ADMIN_URL### The link to click on to confirm the email change.
	 * ###EMAIL###     The proposed new network admin email address.
	 * ###SITENAME###  The name of the network.
	 * ###SITEURL###   The URL to the network.
	 *
	 * @since 4.9.0
	 *
	 * @param string $email_text      Text in the email.
	 * @param array  $new_admin_email {
	 *     Data relating to the new network admin email address.
	 *
	 *     @type string $hash     The secure hash used in the confirmation link URL.
	 *     @type string $newemail The proposed new network admin email address.
	 * }
	 */
	$content = apply_filters( 'new_network_admin_email_content', $email_text, $new_admin_email );

	$current_user = wp_get_current_user();
	$content      = str_replace( '###USERNAME###', $current_user->user_login, $content );
	$content      = str_replace( '###ADMIN_URL###', esc_url( network_admin_url( 'settings.php?network_admin_hash=' . $hash ) ), $content );
	$content      = str_replace( '###EMAIL###', $value, $content );
	$content      = str_replace( '###SITENAME###', wp_specialchars_decode( get_site_option( 'site_name' ), ENT_QUOTES ), $content );
	$content      = str_replace( '###SITEURL###', network_home_url(), $content );

	wp_mail(
		$value,
		sprintf(
			/* translators: Email change notification email subject. %s: Network title. */
			__( '[%s] Network Admin Email Change Request' ),
			wp_specialchars_decode( get_site_option( 'site_name' ), ENT_QUOTES )
		),
		$content
	);

	if ( $switched_locale ) {
		restore_previous_locale();
	}
}

/**
 * Send an email to the old network admin email address when the network admin email address changes.
 *
 * @since 4.9.0
 *
 * @param string $option_name The relevant database option name.
 * @param string $new_email   The new network admin email address.
 * @param string $old_email   The old network admin email address.
 * @param int    $network_id  ID of the network.
 */
function wp_network_admin_email_change_notification( $option_name, $new_email, $old_email, $network_id ) {
	$send = true;

	// Don't send the notification to the default 'admin_email' value.
	if ( 'you@example.com' === $old_email ) {
		$send = false;
	}

	/**
	 * Filters whether to send the network admin email change notification email.
	 *
	 * @since 4.9.0
	 *
	 * @param bool   $send       Whether to send the email notification.
	 * @param string $old_email  The old network admin email address.
	 * @param string $new_email  The new network admin email address.
	 * @param int    $network_id ID of the network.
	 */
	$send = apply_filters( 'send_network_admin_email_change_email', $send, $old_email, $new_email, $network_id );

	if ( ! $send ) {
		return;
	}

	/* translators: Do not translate OLD_EMAIL, NEW_EMAIL, SITENAME, SITEURL: those are placeholders. */
	$email_change_text = __(
		'Hi,

This notice confirms that the network admin email address was changed on ###SITENAME###.

The new network admin email address is ###NEW_EMAIL###.

This email has been sent to ###OLD_EMAIL###

Regards,
All at ###SITENAME###
###SITEURL###'
	);

	$email_change_email = array(
		'to'      => $old_email,
		/* translators: Network admin email change notification email subject. %s: Network title. */
		'subject' => __( '[%s] Network Admin Email Changed' ),
		'message' => $email_change_text,
		'headers' => '',
	);
	// Get network name.
	$network_name = wp_specialchars_decode( get_site_option( 'site_name' ), ENT_QUOTES );

	/**
	 * Filters the contents of the email notification sent when the network admin email address is changed.
	 *
	 * @since 4.9.0
	 *
	 * @param array $email_change_email {
	 *     Used to build wp_mail().
	 *
	 *     @type string $to      The intended recipient.
	 *     @type string $subject The subject of the email.
	 *     @type string $message The content of the email.
	 *         The following strings have a special meaning and will get replaced dynamically:
	 *         - ###OLD_EMAIL### The old network admin email address.
	 *         - ###NEW_EMAIL### The new network admin email address.
	 *         - ###SITENAME###  The name of the network.
	 *         - ###SITEURL###   The URL to the site.
	 *     @type string $headers Headers.
	 * }
	 * @param string $old_email  The old network admin email address.
	 * @param string $new_email  The new network admin email address.
	 * @param int    $network_id ID of the network.
	 */
	$email_change_email = apply_filters( 'network_admin_email_change_email', $email_change_email, $old_email, $new_email, $network_id );

	$email_change_email['message'] = str_replace( '###OLD_EMAIL###', $old_email, $email_change_email['message'] );
	$email_change_email['message'] = str_replace( '###NEW_EMAIL###', $new_email, $email_change_email['message'] );
	$email_change_email['message'] = str_replace( '###SITENAME###', $network_name, $email_change_email['message'] );
	$email_change_email['message'] = str_replace( '###SITEURL###', home_url(), $email_change_email['message'] );

	wp_mail(
		$email_change_email['to'],
		sprintf(
			$email_change_email['subject'],
			$network_name
		),
		$email_change_email['message'],
		$email_change_email['headers']
	);
}

© Evil Twin