Blocking php curl from scraping website content

[knkk]

There is this function:

function disguise_curl($url) 
{ 
$curl = curl_init(); 

// setup headers - used the same headers from Firefox version 2.0.0.6
// below was split up because php.net said the line was too long. :/
$header[0] = "Accept: text/xml,application/xml,application/xhtml+xml,"; 
$header[0] .= "text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"; 
$header[] = "Cache-Control: max-age=0"; 
$header[] = "Connection: keep-alive"; 
$header[] = "Keep-Alive: 300"; 
$header[] = "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7"; 
$header[] = "Accept-Language: en-us,en;q=0.5"; 
$header[] = "Pragma: "; //browsers keep this blank. 

curl_setopt($curl, CURLOPT_URL, $url); 
curl_setopt($curl, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3'); 
curl_setopt($curl, CURLOPT_HTTPHEADER, $header); 
curl_setopt($curl, CURLOPT_REFERER, 'http://www.google.com'); 
curl_setopt($curl, CURLOPT_ENCODING, 'gzip,deflate'); 
curl_setopt($curl, CURLOPT_AUTOREFERER, true); 
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); 
curl_setopt($curl, CURLOPT_TIMEOUT, 10); 

$html = curl_exec($curl); //execute the curl command 
if (!$html) 
{
echo "cURL error number:" .curl_errno($ch);
echo "cURL error:" . curl_error($ch);
exit;
}
 
curl_close($curl); //close the connection 

return $html; //and finally, return $html 
}

...that several people seem to use to scrape content off a website (to state the obvious, you would do "echo disguise_curl($url)").

Is there any way to detect if someone is doing that to my site, and block access to them or show a page with a specific message?

I've experimented with some sites to see if they manage to block access this way, and found [london.vivastreet.co.uk...] manages to do that. I haven't been able to figure out how, but maybe someone can.

A second query: Why would someone write a complicated function like that when get_file_contents($url) does the same? Is it to avoid suspicion?

Thank you very much for your time.

[knkk]

I just realized that the specific URL I am not able to access with that function is [london.vivastreet.co.uk...] Since that link wasn't accessible, I assumed the entire site wasn't accessible, and so posted the home page URL, which appears to be accessible through this function. Any idea why this is happening? Is the "+" in that URL doing something, or is there a way to block URLs from cURL?

[knkk]

I found the issue. I was sending the url to the disguise_curl() function after doing a url_decode first, and so the "cars+london" in the url was becoming "cars london", resulting in the error page I was seeing. So yes, cURL works for this page, too.