PHP cURL: Get target of redirect, without following it

Question

The curl_getinfo function returns a lot of metadata about the result of an HTTP request. However, for some reason it doesn\'t include the bit of information I want at the m

Answer 1

curl doesn't seem to have a function or option to get the redirect target, it can be extracted using various techniques:

From the response:

Apache can respond with a HTML page in case of a 301 redirect (Doesn't seem to be the case with 302's).

If the response has a format similar to:

Moved Permanently
The document has moved here.

Apache/2.2.16 (Debian) Server at www.xxx.yyy Port 80

You can extract the redirect URL using DOMXPath:

$i = 0;
foreach($urls as $url) {
    if(substr($url,0,4) == "http") {
        $c = curl_init($url);
        curl_setopt($c, CURLOPT_RETURNTRANSFER, true);
        $result = @curl_exec($c);
        $status = curl_getinfo($c,CURLINFO_HTTP_CODE);
        curl_close($c);
        $results[$i]['code'] = $status;
        $results[$i]['url'] = $url;

        if($status === 301) {
            $xml = new DOMDocument();
            $xml->loadHTML($result);
            $xpath = new DOMXPath($xml);
            $href = $xpath->query("//*[@href]")->item(0);
            $results[$i]['target'] = $href->attributes->getNamedItem('href')->nodeValue;
        }
        $i++;
    }
}

Using CURLOPT_NOBODY

There is a faster way however, as @gAMBOOKa points out; Using CURLOPT_NOBODY. This approach just sends a HEAD request instead of GET (not downloading the actual content, so it should be faster and more efficient) and stores the response header.

Using a regex the target URL can be extracted from the header:

foreach($urls as $url) {
    if(substr($url,0,4) == "http") {
        $c = curl_init($url);
        curl_setopt($c, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($c, CURLOPT_NOBODY,true);
        curl_setopt($c, CURLOPT_HEADER, true);
        $result = @curl_exec($c);
        $status = curl_getinfo($c,CURLINFO_HTTP_CODE);
        curl_close($c);
        $results[$i]['code'] = $status;
        $results[$i]['url'] = $url;

        if($status === 301 || $status === 302) {
            preg_match("@https?://([-\w\.]+)+(:\d+)?(/([\w/_\-\.]*(\?\S+)?)?)?@",$result,$m);
            $results[$i]['target'] = $m[0];
        }
        $i++;
    }
}