    private function updateHostFromUri()
    {
        $host = $this->uri->getHost();

        if ($host == '') {
            return;
        }

        if (($port = $this->uri->getPort()) !== null) {
            $host .= ':' . $port;
        }

        if (isset($this->headerNames['host'])) {
            $header = $this->headerNames['host'];
        } else {
            $header = 'Host';
            $this->headerNames['host'] = 'Host';
        }
        // Ensure Host is the first header.
        // See: http://tools.ietf.org/html/rfc7230#section-5.4
        $this->headers = [$header => [$host]] + $this->headers;
    }
The software constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component.