/**
  * @ticket 27003
  * @ticket 27927
  */
 function test_get_site_by_path()
 {
     $ids = array('wordpress.org/' => array('domain' => 'wordpress.org', 'path' => '/'), 'wordpress.org/foo/' => array('domain' => 'wordpress.org', 'path' => '/foo/'), 'wordpress.org/foo/bar/' => array('domain' => 'wordpress.org', 'path' => '/foo/bar/'), 'make.wordpress.org/' => array('domain' => 'make.wordpress.org', 'path' => '/'), 'make.wordpress.org/foo/' => array('domain' => 'make.wordpress.org', 'path' => '/foo/'), 'www.w.org/' => array('domain' => 'www.w.org', 'path' => '/'), 'www.w.org/foo/' => array('domain' => 'www.w.org', 'path' => '/foo/'), 'www.w.org/foo/bar/' => array('domain' => 'www.w.org', 'path' => '/foo/bar/'));
     foreach ($ids as &$id) {
         $id = self::factory()->blog->create($id);
     }
     unset($id);
     $this->assertEquals($ids['wordpress.org/'], get_site_by_path('wordpress.org', '/notapath/')->blog_id);
     $this->assertEquals($ids['wordpress.org/'], get_site_by_path('www.wordpress.org', '/notapath/')->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/bar/'], get_site_by_path('wordpress.org', '/foo/bar/baz/')->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/bar/'], get_site_by_path('www.wordpress.org', '/foo/bar/baz/')->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/bar/'], get_site_by_path('wordpress.org', '/foo/bar/baz/', 3)->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/bar/'], get_site_by_path('www.wordpress.org', '/foo/bar/baz/', 3)->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/bar/'], get_site_by_path('wordpress.org', '/foo/bar/baz/', 2)->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/bar/'], get_site_by_path('www.wordpress.org', '/foo/bar/baz/', 2)->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/'], get_site_by_path('wordpress.org', '/foo/bar/baz/', 1)->blog_id);
     $this->assertEquals($ids['wordpress.org/foo/'], get_site_by_path('www.wordpress.org', '/foo/bar/baz/', 1)->blog_id);
     $this->assertEquals($ids['wordpress.org/'], get_site_by_path('wordpress.org', '/', 0)->blog_id);
     $this->assertEquals($ids['wordpress.org/'], get_site_by_path('www.wordpress.org', '/', 0)->blog_id);
     $this->assertEquals($ids['make.wordpress.org/foo/'], get_site_by_path('make.wordpress.org', '/foo/bar/baz/qux/', 4)->blog_id);
     $this->assertEquals($ids['make.wordpress.org/foo/'], get_site_by_path('www.make.wordpress.org', '/foo/bar/baz/qux/', 4)->blog_id);
     $this->assertEquals($ids['www.w.org/'], get_site_by_path('www.w.org', '/', 0)->blog_id);
     $this->assertEquals($ids['www.w.org/'], get_site_by_path('www.w.org', '/notapath/')->blog_id);
     $this->assertEquals($ids['www.w.org/foo/bar/'], get_site_by_path('www.w.org', '/foo/bar/baz/')->blog_id);
     $this->assertEquals($ids['www.w.org/foo/'], get_site_by_path('www.w.org', '/foo/bar/baz/', 1)->blog_id);
     // A site installed with www will not be found by the root domain.
     $this->assertFalse(get_site_by_path('w.org', '/'));
     $this->assertFalse(get_site_by_path('w.org', '/notapath/'));
     $this->assertFalse(get_site_by_path('w.org', '/foo/bar/baz/'));
     $this->assertFalse(get_site_by_path('w.org', '/foo/bar/baz/', 1));
     // A site will not be found by its root domain when an invalid subdomain is requested.
     $this->assertFalse(get_site_by_path('invalid.wordpress.org', '/'));
     $this->assertFalse(get_site_by_path('invalid.wordpress.org', '/foo/bar/'));
 }

/**
 * Check if a domain belongs to a mapped network
 *
 * @param stdClass|null $network Site object if already found, null otherwise
 * @param string $domain Domain we're looking for
 * @return stdClass|null Site object if already found, null otherwise
 */
function check_mappings_for_site($site, $domain, $path, $path_segments)
{
    // Have we already matched? (Allows other plugins to match first)
    if (!empty($site)) {
        return $site;
    }
    $domains = get_possible_mapped_domains($domain);
    $mapping = Network_Mapping::get_active_by_domain($domains);
    if (empty($mapping) || is_wp_error($mapping)) {
        return $site;
    }
    // Fetch the actual data for the site
    $mapped_network = $mapping->get_network();
    if (empty($mapped_network)) {
        return $site;
    }
    // We found a network, now check for the site. Replace mapped domain with
    // network's original to find.
    $mapped_domain = $mapping->get_domain();
    if (substr($mapped_domain, 0, 4) === 'www.') {
        $mapped_domain = substr($mapped_domain, 4);
    }
    $subdomain = substr($domain, 0, -strlen($mapped_domain));
    return get_site_by_path($subdomain . $mapped_network->domain, $path, $path_segments);
}

 /**
  * @ticket 27003
  * @ticket 27927
  * @dataProvider data_get_site_by_path
  *
  * @param string $expected_key The array key associated with expected data for the test.
  * @param string $domain       The requested domain.
  * @param string $path         The requested path.
  * @param int    $segments     Optional. Number of segments to use in `get_site_by_path()`.
  */
 public function test_get_site_by_path($expected_key, $domain, $path, $segments = null)
 {
     $site = get_site_by_path($domain, $path, $segments);
     if ($expected_key) {
         $this->assertEquals(self::$site_ids[$expected_key], $site->blog_id);
     } else {
         $this->assertFalse($site);
     }
 }

 /**
  * Find site by domain.
  *
  * @param  string $domain The domain to look for.
  *
  * @return \WP_Site|null
  */
 protected function find_site($domain)
 {
     if (empty($domain) || !is_string($domain)) {
         return;
     }
     // Get site by domain.
     if ($site = get_site_by_path($domain, '')) {
         return $site instanceof WP_Site ? $site : new WP_Site($site);
     }
     // Redirect to main site if no site is found.
     if ($site = get_site(1)) {
         $scheme = is_ssl() ? 'https' : 'http';
         $uri = sprintf('%s://%s', $scheme, $site->domain);
         header('Location: ' . $uri);
         die;
     }
 }

	/**
	 * @ticket 27003
	 */
	function test_get_site_by_path() {
		$ids = array(
			'wordpress.org/'              => array( 'domain' => 'wordpress.org',      'path' => '/' ),
			'wordpress.org/foo/'          => array( 'domain' => 'wordpress.org',      'path' => '/foo/' ),
			'wordpress.org/foo/bar/'      => array( 'domain' => 'wordpress.org',      'path' => '/foo/bar/' ),
			'make.wordpress.org/'         => array( 'domain' => 'make.wordpress.org', 'path' => '/' ),
			'make.wordpress.org/foo/'     => array( 'domain' => 'make.wordpress.org', 'path' => '/foo/' ),
		);

		foreach ( $ids as &$id ) {
			$id = $this->factory->blog->create( $id );
		}
		unset( $id );

		$this->assertEquals( $ids['wordpress.org/'],
			get_site_by_path( 'wordpress.org', '/notapath/' )->blog_id );

		$this->assertEquals( $ids['wordpress.org/foo/bar/'],
			get_site_by_path( 'wordpress.org', '/foo/bar/baz/' )->blog_id );

		$this->assertEquals( $ids['wordpress.org/foo/bar/'],
			get_site_by_path( 'wordpress.org', '/foo/bar/baz/', 3 )->blog_id );

		$this->assertEquals( $ids['wordpress.org/foo/bar/'],
			get_site_by_path( 'wordpress.org', '/foo/bar/baz/', 2 )->blog_id );

		$this->assertEquals( $ids['wordpress.org/foo/'],
			get_site_by_path( 'wordpress.org', '/foo/bar/baz/', 1 )->blog_id );

		$this->assertEquals( $ids['wordpress.org/'],
			get_site_by_path( 'wordpress.org', '/', 0 )->blog_id );

		$this->assertEquals( $ids['make.wordpress.org/foo/'],
			get_site_by_path( 'make.wordpress.org', '/foo/bar/baz/qux/', 4 )->blog_id );
	}

/**
 * Identifies the network and site of a requested domain and path and populates the
 * corresponding network and site global objects as part of the multisite bootstrap process.
 *
 * Prior to 4.6.0, this was a procedural block in `ms-settings.php`. It was wrapped into
 * a function to facilitate unit tests. It should not be used outside of core.
 *
 * Usually, it's easier to query the site first, which then declares its network.
 * In limited situations, we either can or must find the network first.
 *
 * If a network and site are found, a `true` response will be returned so that the
 * request can continue.
 *
 * If neither a network or site is found, `false` or a URL string will be returned
 * so that either an error can be shown or a redirect can occur.
 *
 * @since 4.6.0
 * @access private
 *
 * @global wpdb       $wpdb         WordPress database abstraction object.
 * @global WP_Network $current_site The current network.
 * @global WP_Site    $current_blog The current site.
 *
 * @param string $domain    The requested domain.
 * @param string $path      The requested path.
 * @param bool   $subdomain Whether a subdomain (true) or subdirectory (false) configuration.
 * @return bool|string True if bootstrap successfully populated `$current_blog` and `$current_site`.
 *                     False if bootstrap could not be properly completed.
 *                     Redirect URL if parts exist, but the request as a whole can not be fulfilled.
 */
function ms_load_current_site_and_network($domain, $path, $subdomain = false)
{
    global $wpdb, $current_site, $current_blog;
    // If the network is defined in wp-config.php, we can simply use that.
    if (defined('DOMAIN_CURRENT_SITE') && defined('PATH_CURRENT_SITE')) {
        $current_site = new stdClass();
        $current_site->id = defined('SITE_ID_CURRENT_SITE') ? SITE_ID_CURRENT_SITE : 1;
        $current_site->domain = DOMAIN_CURRENT_SITE;
        $current_site->path = PATH_CURRENT_SITE;
        if (defined('BLOG_ID_CURRENT_SITE')) {
            $current_site->blog_id = BLOG_ID_CURRENT_SITE;
        } elseif (defined('BLOGID_CURRENT_SITE')) {
            // deprecated.
            $current_site->blog_id = BLOGID_CURRENT_SITE;
        }
        if (0 === strcasecmp($current_site->domain, $domain) && 0 === strcasecmp($current_site->path, $path)) {
            $current_blog = get_site_by_path($domain, $path);
        } elseif ('/' !== $current_site->path && 0 === strcasecmp($current_site->domain, $domain) && 0 === stripos($path, $current_site->path)) {
            // If the current network has a path and also matches the domain and path of the request,
            // we need to look for a site using the first path segment following the network's path.
            $current_blog = get_site_by_path($domain, $path, 1 + count(explode('/', trim($current_site->path, '/'))));
        } else {
            // Otherwise, use the first path segment (as usual).
            $current_blog = get_site_by_path($domain, $path, 1);
        }
    } elseif (!$subdomain) {
        /*
         * A "subdomain" install can be re-interpreted to mean "can support any domain".
         * If we're not dealing with one of these installs, then the important part is determining
         * the network first, because we need the network's path to identify any sites.
         */
        if (!($current_site = wp_cache_get('current_network', 'site-options'))) {
            // Are there even two networks installed?
            $one_network = $wpdb->get_row("SELECT * FROM {$wpdb->site} LIMIT 2");
            // [sic]
            if (1 === $wpdb->num_rows) {
                $current_site = new WP_Network($one_network);
                wp_cache_add('current_network', $current_site, 'site-options');
            } elseif (0 === $wpdb->num_rows) {
                // A network not found hook should fire here.
                return false;
            }
        }
        if (empty($current_site)) {
            $current_site = WP_Network::get_by_path($domain, $path, 1);
        }
        if (empty($current_site)) {
            /**
             * Fires when a network cannot be found based on the requested domain and path.
             *
             * At the time of this action, the only recourse is to redirect somewhere
             * and exit. If you want to declare a particular network, do so earlier.
             *
             * @since 4.4.0
             *
             * @param string $domain       The domain used to search for a network.
             * @param string $path         The path used to search for a path.
             */
            do_action('ms_network_not_found', $domain, $path);
            return false;
        } elseif ($path === $current_site->path) {
            $current_blog = get_site_by_path($domain, $path);
        } else {
            // Search the network path + one more path segment (on top of the network path).
            $current_blog = get_site_by_path($domain, $path, substr_count($current_site->path, '/'));
        }
    } else {
        // Find the site by the domain and at most the first path segment.
        $current_blog = get_site_by_path($domain, $path, 1);
        if ($current_blog) {
//.........这里部分代码省略.........

         }
     }
     if (empty($current_site)) {
         $current_site = get_network_by_path($domain, $path, 1);
     }
     if (empty($current_site)) {
         ms_not_installed();
     } elseif ($path === $current_site->path) {
         $current_blog = get_site_by_path($domain, $path);
     } else {
         // Search the network path + one more path segment (on top of the network path).
         $current_blog = get_site_by_path($domain, $path, substr_count($current_site->path, '/'));
     }
 } else {
     // Find the site by the domain and at most the first path segment.
     $current_blog = get_site_by_path($domain, $path, 1);
     if ($current_blog) {
         $current_site = wp_get_network($current_blog->site_id ? $current_blog->site_id : 1);
     } else {
         // If you don't have a site with the same domain/path as a network, you're pretty screwed, but:
         $current_site = get_network_by_path($domain, $path, 1);
     }
 }
 // The network declared by the site trumps any constants.
 if ($current_blog && $current_blog->site_id != $current_site->id) {
     $current_site = wp_get_network($current_blog->site_id);
 }
 // No network has been found, bail.
 if (empty($current_site)) {
     ms_not_installed();
 }

 function go_to($url)
 {
     global $wpdb;
     global $current_site, $current_blog, $blog_id, $switched, $_wp_switched_stack, $public, $table_prefix, $current_user, $wp_roles;
     // note: the WP and WP_Query classes like to silently fetch parameters
     // from all over the place (globals, GET, etc), which makes it tricky
     // to run them more than once without very carefully clearing everything
     $_GET = $_POST = array();
     foreach (array('query_string', 'id', 'postdata', 'authordata', 'day', 'currentmonth', 'page', 'pages', 'multipage', 'more', 'numpages', 'pagenow') as $v) {
         if (isset($GLOBALS[$v])) {
             unset($GLOBALS[$v]);
         }
     }
     $parts = parse_url($url);
     if (isset($parts['scheme'])) {
         // set the HTTP_HOST
         $GLOBALS['_SERVER']['HTTP_HOST'] = $parts['host'];
         $req = $parts['path'];
         if (isset($parts['query'])) {
             $req .= '?' . $parts['query'];
             // parse the url query vars into $_GET
             parse_str($parts['query'], $_GET);
         }
     } else {
         $req = $url;
     }
     if (!isset($parts['query'])) {
         $parts['query'] = '';
     }
     // Scheme
     if (0 === strpos($req, '/wp-admin') && force_ssl_admin()) {
         $_SERVER['HTTPS'] = 'on';
     } else {
         unset($_SERVER['HTTPS']);
     }
     // Set this for bp_core_set_uri_globals()
     $GLOBALS['_SERVER']['REQUEST_URI'] = $req;
     unset($_SERVER['PATH_INFO']);
     // setup $current_site and $current_blog globals for multisite based on
     // REQUEST_URI; mostly copied from /wp-includes/ms-settings.php
     if (is_multisite()) {
         $current_blog = $current_site = $blog_id = null;
         $domain = addslashes($_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);
             }
         }
         $path = stripslashes($_SERVER['REQUEST_URI']);
         // Get a cleaned-up version of the wp_version string
         // (strip -src, -alpha, etc which may trip up version_compare())
         $wp_version = (double) $GLOBALS['wp_version'];
         if (version_compare($wp_version, '4.4', '>=')) {
             if (!($current_site = wp_cache_get('current_network', 'site-options'))) {
                 // Are there even two networks installed?
                 $one_network = $wpdb->get_row("SELECT * FROM {$wpdb->site} LIMIT 2");
                 // [sic]
                 if (1 === $wpdb->num_rows) {
                     $current_site = new WP_Network($one_network);
                     wp_cache_add('current_network', $current_site, 'site-options');
                 } elseif (0 === $wpdb->num_rows) {
                     ms_not_installed($domain, $path);
                 }
             }
             if (empty($current_site)) {
                 $current_site = WP_Network::get_by_path($domain, $path, 1);
             }
             // The network declared by the site trumps any constants.
             if ($current_blog && $current_blog->site_id != $current_site->id) {
                 $current_site = WP_Network::get_instance($current_blog->site_id);
             }
             if (empty($current_site)) {
                 do_action('ms_network_not_found', $domain, $path);
                 ms_not_installed($domain, $path);
             } elseif ($path === $current_site->path) {
                 $current_blog = get_site_by_path($domain, $path);
             } else {
                 // Search the network path + one more path segment (on top of the network path).
                 $current_blog = get_site_by_path($domain, $path, substr_count($current_site->path, '/'));
             }
             // Figure out the current network's main site.
             if (empty($current_site->blog_id)) {
                 if ($current_blog->domain === $current_site->domain && $current_blog->path === $current_site->path) {
                     $current_site->blog_id = $current_blog->blog_id;
                 } elseif (!($current_site->blog_id = wp_cache_get('network:' . $current_site->id . ':main_site', 'site-options'))) {
                     $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));
                     wp_cache_add('network:' . $current_site->id . ':main_site', $current_site->blog_id, 'site-options');
                 }
             }
             $blog_id = $current_blog->blog_id;
             $public = $current_blog->public;
             if (empty($current_blog->site_id)) {
                 // This dates to [MU134] and shouldn't be relevant anymore,
                 // but it could be possible for arguments passed to insert_blog() etc.
                 $current_blog->site_id = 1;
             }
//.........这里部分代码省略.........

<?php

/**
 * Sets up $current_site and $current_blog for Multi-site domain routing.
 *
 * @see file: wp/wp-includes/ms-settings.php
 * @see https://wordpress.org/plugins/wordpress-mu-domain-mapping/
 */
if (!isset($_SERVER['HTTP_HOST'])) {
    return;
}
if (file_exists(dirname(__FILE__) . '/local-sunrise.php')) {
    require_once dirname(__FILE__) . '/local-sunrise.php';
}
// If we can't identify the current site, assume it's blog_id = 1
if (!get_site_by_path($_SERVER['HTTP_HOST'], '/')) {
    $current_blog = $wpdb->get_row("SELECT * FROM {$wpdb->blogs} WHERE blog_id = 1 LIMIT 1");
    $current_site = $wpdb->get_row("SELECT * from {$wpdb->site} WHERE id = '{$current_blog->site_id}' LIMIT 0,1");
    $current_site->blog_id = 1;
    $current_site->domain = $_SERVER['HTTP_HOST'];
}

 /**
  * @ticket 37053
  */
 public function test_get_site_by_path_returns_wp_site()
 {
     add_filter('pre_get_site_by_path', array($this, 'filter_pre_get_site_by_path'), 10, 3);
     $site = get_site_by_path('example.com', '/foo/');
     remove_filter('pre_get_site_by_path', array($this, 'filter_pre_get_site_by_path'), 10);
     $this->assertInstanceOf('WP_Site', $site);
 }