src/includes/classes/Core/Utils/Sri.php
protected function isLocal(string $url)
    {
        if (mb_stripos($url, '//') === false) {
            return true; // Relative.
        } elseif ($this->current_host) {
            return mb_stripos($url, '//'.$this->current_host.'/') !== false;
        }
        return null; // Unable to determine.
    }
protected function isLocal(string $url)
    {
        if (mb_stripos($url, '//') === false) {
            return true; // Relative.
        } elseif ($this->current_host) {
            return mb_stripos($url, '//'.$this->current_host.'/') !== false;
        }
        return null; // Unable to determine.
    }
URL is local?

@since 170215.53419 SRI utils.

@param string $url URL to get SRI for.

@return bool|null True if URL is local.