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;
}

/**
 * Gets 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;
	}
}

/**
 * Gets the number of active sites on the 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    User role.
 * @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;
}

/**
 * Removes 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 );
	}

	$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' );
		}
	}

	clean_user_cache( $user_id );
	restore_current_blog();

	return true;
}

/**
 * Gets 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;
}

/**
 * Gets 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 Website domain.
 * @param string $path   Optional. Not required for subdomain installations. Default '/'.
 * @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;
			}

			if ( str_ends_with( $normalized_email, ".$banned_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 );
}

/**
 * Sanitizes and validates 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. There are problems with them blocking some emails from WordPress. 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',
			sprintf(
				/* translators: %s: Link to the login page. */
				__( '<strong>Error:</strong> This email address is already registered. <a href="%s">Log in</a> with this address or choose another one.' ),
				wp_login_url()
			)
		);
	}

	// 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 site name provided by the user. Must be unique.
 * @param string         $blog_title The site title provided by the user.
 * @param WP_User|string $user       Optional. The user object to check against the new site name.
 *                                   Default empty string.
 * @return array {
 *     Array of domain, path, site name, site 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 site 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!' ) );
	}

	/*
	 * Do not allow users to create a site that matches an existing user's login name,
	 * unless it's the user's own username.
	 */
	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, site name, site 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 Site 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 );
}

/**
 * Records 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 );
}

/**
 * Records 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 );
}

/**
 * Sends 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 = $user && switch_to_user_locale( $user->ID );

	$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 site, 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.