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 moment, which is the target URL if the request returns an HTTP redirection code.

I'm not using CURLOPT_FOLLOWLOCATION because I want to handle specific redirect codes as special cases.

If cURL can follow redirects, why can't it tell me what they redirect to when it isn't following them?

Of course, I could set the CURLOPT_HEADER flag and pick out the Location header. But is there a more efficient way?

Answer 1

This can be done in 4 steps:

Step 1. Initialise curl

curl_init($ch); //initialise the curl handle
//COOKIESESSION is optional, use if you want to keep cookies in memory
curl_setopt($this->ch, CURLOPT_COOKIESESSION, true);

Step 2. Get the headers for $url

curl_setopt($ch, CURLOPT_URL, $url); //specify your URL
curl_setopt($ch, CURLOPT_HEADER, true); //include headers in http data
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false); //don't follow redirects
$http_data = curl_exec($ch); //hit the $url
$curl_info = curl_getinfo($ch);
$headers = substr($http_data, 0, $curl_info['header_size']); //split out header

Step 3. Check if you have the correct response code

if (!($curl_info['http_code']>299 && $curl_info['http_code']<309)) {
  //return, echo, die, whatever you like
  return 'Error - http code'.$curl_info['http_code'].' received.';
}

Step 4. Parse the headers to get the new URL

preg_match("!\r\n(?:Location|URI): *(.*?) *\r\n!", $headers, $matches);
$url = $matches[1];

Once you have the new URL you can then repeat steps 2-4 as often as you like.