HtmlDocument::validateImage

protected function validateImage($url, $skipForPrivateIp = false)
{
	$httpClient = new HttpClient();
	$httpClient->setTimeout(5);
	$httpClient->setStreamTimeout(5);
	$httpClient->setPrivateIp(false);
	$httpClient->setHeader('User-Agent', UrlPreview::USER_AGENT);

	if (!$httpClient->query('HEAD', $url))
	{
		$errorCode = array_key_first($httpClient->getError());
		return ($skipForPrivateIp && $errorCode === 'PRIVATE_IP');
	}

	if ($httpClient->getStatus() !== 200)
	{
		return false;
	}

	$contentType = $httpClient->getHeaders()->getContentType();

	return MimeType::isImage($contentType);
}