How can I find where I will be redirected using cURL?

Question

I\'m trying to make curl follow a redirect but I can\'t quite get it to work right. I have a string that I want to send as a GET param to a server and get the resulting URL.

Answer 1

The chosen answer here is decent but its case sensitive, doesn't protect against relative location: headers (which some sites do) or pages that might actually have the phrase Location: in their content... (which zillow currently does).

A bit sloppy, but a couple quick edits to make this a bit smarter are:

function getOriginalURL($url) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    $result = curl_exec($ch);
    $httpStatus = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    // if it's not a redirection (3XX), move along
    if ($httpStatus < 300 || $httpStatus >= 400)
        return $url;

    // look for a location: header to find the target URL
    if(preg_match('/location: (.*)/i', $result, $r)) {
        $location = trim($r[1]);

        // if the location is a relative URL, attempt to make it absolute
        if (preg_match('/^\/(.*)/', $location)) {
            $urlParts = parse_url($url);
            if ($urlParts['scheme'])
                $baseURL = $urlParts['scheme'].'://';

            if ($urlParts['host'])
                $baseURL .= $urlParts['host'];

            if ($urlParts['port'])
                $baseURL .= ':'.$urlParts['port'];

            return $baseURL.$location;
        }

        return $location;
    }
    return $url;
}

Note that this still only goes 1 redirection deep. To go deeper, you actually need to get the content and follow the redirects.