CI_DB_mysqli_driver::db_connect PHP Method

    public function db_connect($persistent = FALSE)
    {
        // Do we have a socket path?
        if ($this->hostname[0] === '/') {
            $hostname = NULL;
            $port = NULL;
            $socket = $this->hostname;
        } else {
            // Persistent connection support was added in PHP 5.3.0
            $hostname = $persistent === TRUE && is_php('5.3') ? 'p:' . $this->hostname : $this->hostname;
            $port = empty($this->port) ? NULL : $this->port;
            $socket = NULL;
        }
        $client_flags = $this->compress === TRUE ? MYSQLI_CLIENT_COMPRESS : 0;
        $this->_mysqli = mysqli_init();
        $this->_mysqli->options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);
        if (isset($this->stricton)) {
            if ($this->stricton) {
                $this->_mysqli->options(MYSQLI_INIT_COMMAND, 'SET SESSION sql_mode = CONCAT(@@sql_mode, ",", "STRICT_ALL_TABLES")');
            } else {
                $this->_mysqli->options(MYSQLI_INIT_COMMAND, 'SET SESSION sql_mode =
					REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
					@@sql_mode,
					"STRICT_ALL_TABLES,", ""),
					",STRICT_ALL_TABLES", ""),
					"STRICT_ALL_TABLES", ""),
					"STRICT_TRANS_TABLES,", ""),
					",STRICT_TRANS_TABLES", ""),
					"STRICT_TRANS_TABLES", "")');
            }
        }
        if (is_array($this->encrypt)) {
            $ssl = array();
            empty($this->encrypt['ssl_key']) or $ssl['key'] = $this->encrypt['ssl_key'];
            empty($this->encrypt['ssl_cert']) or $ssl['cert'] = $this->encrypt['ssl_cert'];
            empty($this->encrypt['ssl_ca']) or $ssl['ca'] = $this->encrypt['ssl_ca'];
            empty($this->encrypt['ssl_capath']) or $ssl['capath'] = $this->encrypt['ssl_capath'];
            empty($this->encrypt['ssl_cipher']) or $ssl['cipher'] = $this->encrypt['ssl_cipher'];
            if (!empty($ssl)) {
                if (isset($this->encrypt['ssl_verify'])) {
                    if ($this->encrypt['ssl_verify']) {
                        defined('MYSQLI_OPT_SSL_VERIFY_SERVER_CERT') && $this->_mysqli->options(MYSQLI_OPT_SSL_VERIFY_SERVER_CERT, TRUE);
                    } elseif (defined('MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT')) {
                        $this->_mysqli->options(MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT, TRUE);
                    }
                }
                $client_flags |= MYSQLI_CLIENT_SSL;
                $this->_mysqli->ssl_set(isset($ssl['key']) ? $ssl['key'] : NULL, isset($ssl['cert']) ? $ssl['cert'] : NULL, isset($ssl['ca']) ? $ssl['ca'] : NULL, isset($ssl['capath']) ? $ssl['capath'] : NULL, isset($ssl['cipher']) ? $ssl['cipher'] : NULL);
            }
        }
        if (@$this->_mysqli->real_connect($hostname, $this->username, $this->password, $this->database, $port, $socket, $client_flags)) {
            // Prior to version 5.7.3, MySQL silently downgrades to an unencrypted connection if SSL setup fails
            if ($client_flags & MYSQLI_CLIENT_SSL && version_compare($this->_mysqli->client_info, '5.7.3', '<=') && empty($this->_mysqli->query("SHOW STATUS LIKE 'ssl_cipher'")->fetch_object()->Value)) {
                $this->_mysqli->close();
                $message = 'MySQLi was configured for an SSL connection, but got an unencrypted connection instead!';
                log_message('error', $message);
                return $this->db->db_debug ? $this->db->display_error($message, '', TRUE) : FALSE;
            }
            return $this->_mysqli;
        }
        return FALSE;
    }