get_dashboard_url

	return apply_filters( 'set_url_scheme', $url, $scheme, $orig_scheme );
}

/**
 * Retrieves the URL to the user's dashboard.
 *
 * If a user does not belong to any site, the global user dashboard is used. If the user
 * belongs to the current site, the dashboard for the current site is returned. If the user
 * cannot edit the current site, the dashboard to the user's primary site is returned.
 *
 * @since 3.1.0
 *
 * @param int    $user_id Optional. User ID. Defaults to current user.
 * @param string $path    Optional path relative to the dashboard. Use only paths known to
 *                        both site and user admins. Default empty.
 * @param string $scheme  The scheme to use. Default is 'admin', which obeys force_ssl_admin()
 *                        and is_ssl(). 'http' or 'https' can be passed to force those schemes.
 * @return string Dashboard URL link with optional path appended.
 */
function get_dashboard_url( $user_id = 0, $path = '', $scheme = 'admin' ) {
	$user_id = $user_id ? (int) $user_id : get_current_user_id();

	$blogs = get_blogs_of_user( $user_id );

	if ( is_multisite() && ! user_can( $user_id, 'manage_network' ) && empty( $blogs ) ) {
		$url = user_admin_url( $path, $scheme );
	} elseif ( ! is_multisite() ) {
		$url = admin_url( $path, $scheme );
	} else {
		$current_blog = get_current_blog_id();

		if ( $current_blog && ( user_can( $user_id, 'manage_network' ) || in_array( $current_blog, array_keys( $blogs ), true ) ) ) {
			$url = admin_url( $path, $scheme );
		} else {
			$active = get_active_blog_for_user( $user_id );