wp_fix_server_vars() WordPress Function

function wp_fix_server_vars() {
	global $PHP_SELF;

	$default_server_values = array(
		'SERVER_SOFTWARE' => '',
		'REQUEST_URI'     => '',
	);

	$_SERVER = array_merge( $default_server_values, $_SERVER );

	// Fix for IIS when running with PHP ISAPI.
	if ( empty( $_SERVER['REQUEST_URI'] ) || ( 'cgi-fcgi' !== PHP_SAPI && preg_match( '/^Microsoft-IIS\//', $_SERVER['SERVER_SOFTWARE'] ) ) ) {

		if ( isset( $_SERVER['HTTP_X_ORIGINAL_URL'] ) ) {
			// IIS Mod-Rewrite.
			$_SERVER['REQUEST_URI'] = $_SERVER['HTTP_X_ORIGINAL_URL'];
		} elseif ( isset( $_SERVER['HTTP_X_REWRITE_URL'] ) ) {
			// IIS Isapi_Rewrite.
			$_SERVER['REQUEST_URI'] = $_SERVER['HTTP_X_REWRITE_URL'];
		} else {
			// Use ORIG_PATH_INFO if there is no PATH_INFO.
			if ( ! isset( $_SERVER['PATH_INFO'] ) && isset( $_SERVER['ORIG_PATH_INFO'] ) ) {
				$_SERVER['PATH_INFO'] = $_SERVER['ORIG_PATH_INFO'];
			}

			// Some IIS + PHP configurations put the script-name in the path-info (no need to append it twice).
			if ( isset( $_SERVER['PATH_INFO'] ) ) {
				if ( $_SERVER['PATH_INFO'] == $_SERVER['SCRIPT_NAME'] ) {
					$_SERVER['REQUEST_URI'] = $_SERVER['PATH_INFO'];
				} else {
					$_SERVER['REQUEST_URI'] = $_SERVER['SCRIPT_NAME'] . $_SERVER['PATH_INFO'];
				}
			}

			// Append the query string if it exists and isn't null.
			if ( ! empty( $_SERVER['QUERY_STRING'] ) ) {
				$_SERVER['REQUEST_URI'] .= '?' . $_SERVER['QUERY_STRING'];
			}
		}
	}

	// Fix for PHP as CGI hosts that set SCRIPT_FILENAME to something ending in php.cgi for all requests.
	if ( isset( $_SERVER['SCRIPT_FILENAME'] ) && ( strpos( $_SERVER['SCRIPT_FILENAME'], 'php.cgi' ) == strlen( $_SERVER['SCRIPT_FILENAME'] ) - 7 ) ) {
		$_SERVER['SCRIPT_FILENAME'] = $_SERVER['PATH_TRANSLATED'];
	}

	// Fix for Dreamhost and other PHP as CGI hosts.
	if ( isset( $_SERVER['SCRIPT_NAME'] ) && ( strpos( $_SERVER['SCRIPT_NAME'], 'php.cgi' ) !== false ) ) {
		unset( $_SERVER['PATH_INFO'] );
	}

	// Fix empty PHP_SELF.
	$PHP_SELF = $_SERVER['PHP_SELF'];
	if ( empty( $PHP_SELF ) ) {
		$_SERVER['PHP_SELF'] = preg_replace( '/(\?.*)?$/', '', $_SERVER['REQUEST_URI'] );
		$PHP_SELF            = $_SERVER['PHP_SELF'];
	}

	wp_populate_basic_auth_from_authorization_header();
}