WordPress/wp-includes/ms-settings.php

<?php
/**
 * Used to setup and fix common variables and include
 * the Multisite procedural and class library.
 *
 * Allows for some configuration in wp-config.php (see ms-default-constants.php)
 *
 * @package WordPress
 * @subpackage Multisite
 */

/** Include Multisite initialization functions */
require( ABSPATH . WPINC . '/ms-load.php' );
require( ABSPATH . WPINC . '/ms-default-constants.php' );

if ( defined( 'SUNRISE' ) )
	include_once( WP_CONTENT_DIR . '/sunrise.php' );

if ( isset( $current_site ) && isset( $current_blog ) )
	return;

$domain = addslashes( $_SERVER['HTTP_HOST'] );
if ( false !== strpos( $domain, ':' ) ) {
	if ( substr( $domain, -3 ) == ':80' ) {
		$domain = substr( $domain, 0, -3 );
		$_SERVER['HTTP_HOST'] = substr( $_SERVER['HTTP_HOST'], 0, -3 );
	} elseif ( substr( $domain, -4 ) == ':443' ) {
		$domain = substr( $domain, 0, -4 );
		$_SERVER['HTTP_HOST'] = substr( $_SERVER['HTTP_HOST'], 0, -4 );
	} else {
		wp_die( 'Multisite only works without the port number in the URL.' );
	}
}

$domain = rtrim( $domain, '.' );
$cookie_domain = $domain;
if ( substr( $cookie_domain, 0, 4 ) == 'www.' )
	$cookie_domain = substr( $cookie_domain, 4 );

$path = preg_replace( '|([a-z0-9-]+.php.*)|', '', $_SERVER['REQUEST_URI'] );
$path = str_replace ( '/wp-admin/', '/', $path );
$path = preg_replace( '|(/[a-z0-9-]+?/).*|', '$1', $path );

$current_site = wpmu_current_site();
if ( ! isset( $current_site->blog_id ) )
	$current_site->blog_id = $wpdb->get_var( $wpdb->prepare( "SELECT blog_id FROM $wpdb->blogs WHERE domain = %s AND path = %s", $current_site->domain, $current_site->path ) );

if ( is_subdomain_install() ) {
	$current_blog = wp_cache_get( 'current_blog_' . $domain, 'site-options' );
	if ( !$current_blog ) {
		$current_blog = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->blogs WHERE domain = %s", $domain ) );
		if ( $current_blog )
			wp_cache_set( 'current_blog_' . $domain, $current_blog, 'site-options' );
	}
	if ( $current_blog && $current_blog->site_id != $current_site->id )
		$current_site = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->site WHERE id = %d", $current_blog->site_id ) );
	else
		$blogname = substr( $domain, 0, strpos( $domain, '.' ) );
} else {
	$blogname = htmlspecialchars( substr( $_SERVER[ 'REQUEST_URI' ], strlen( $path ) ) );
	if ( false !== strpos( $blogname, '/' ) )
		$blogname = substr( $blogname, 0, strpos( $blogname, '/' ) );
	if ( false !== strpos( $blogname, '?' ) )
		$blogname = substr( $blogname, 0, strpos( $blogname, '?' ) );
	$reserved_blognames = array( 'page', 'comments', 'blog', 'wp-admin', 'wp-includes', 'wp-content', 'files', 'feed' );
	if ( $blogname != '' && ! in_array( $blogname, $reserved_blognames ) && ! is_file( $blogname ) )
		$path .= $blogname . '/';
	$current_blog = wp_cache_get( 'current_blog_' . $domain . $path, 'site-options' );
	if ( ! $current_blog ) {
		$current_blog = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->blogs WHERE domain = %s AND path = %s", $domain, $path ) );
		if ( $current_blog )
			wp_cache_set( 'current_blog_' . $domain . $path, $current_blog, 'site-options' );
	}
}

if ( ! defined( 'WP_INSTALLING' ) && is_subdomain_install() && ! is_object( $current_blog ) ) {
	if ( defined( 'NOBLOGREDIRECT' ) ) {
		$destination = NOBLOGREDIRECT;
		if ( '%siteurl%' == $destination )
			$destination = "http://" . $current_site->domain . $current_site->path;
	} else {
		$destination = 'http://' . $current_site->domain . $current_site->path . 'wp-signup.php?new=' . str_replace( '.' . $current_site->domain, '', $domain );
	}
	header( 'Location: ' . $destination );
	die();
}

if ( ! defined( 'WP_INSTALLING' ) ) {
	if ( $current_site && ! $current_blog ) {
		if ( $current_site->domain != $_SERVER[ 'HTTP_HOST' ] ) {
			header( 'Location: http://' . $current_site->domain . $current_site->path );
			exit;
		}
		$current_blog = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->blogs WHERE domain = %s AND path = %s", $current_site->domain, $current_site->path ) );
	}
	if ( ! $current_blog || ! $current_site )
		is_installed();
}

$blog_id = $current_blog->blog_id;
$public  = $current_blog->public;

if ( empty( $current_blog->site_id ) )
	$current_blog->site_id = 1;
$site_id = $current_blog->site_id;

$current_site = get_current_site_name( $current_site );

if ( ! $blog_id ) {
	if ( defined('WP_INSTALLING') ) {
		$current_blog->blog_id = $blog_id = 1;
    } else {
		$msg = ! $wpdb->get_var( "SHOW TABLES LIKE '$wpdb->site'" ) ? __( 'Database tables are missing.' ) : '';
		wp_die( __( 'No blog by that name on this system.' ) . $msg );
    }
}

$wpdb->blogid = $current_blog->blog_id;
$wpdb->siteid = $current_blog->site_id;
$wpdb->set_prefix( $table_prefix ); // set up blog tables
$table_prefix = $wpdb->get_blog_prefix();

// need to init cache again after blog_id is set
wp_start_object_cache();

// Define upload directory constants
ms_default_constants( 'uploads' );

?>