Question

I have the following code and when i try to get a value from the array $headers nothing appears, but when I use var_dump($headers) it shows all the array values. What Am I doing wrong?

function linkcheck($url) {
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_NOBODY, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    $headers = explode("\n", curl_exec($ch));
    curl_close($ch);

    switch ($headers[18]) {
        case "Location: https://somewebsite.com/welcome":
            echo "Actice";
            break;
        case "Location: https://somewebsite.com/no_such_link":
            echo "Inactive";
            break;

    }
}

echo linkcheck('http://somewebsite.com/54sdf');

Output

array(37) {
  [0]=>
  string(19) "HTTP/1.1 302 Found
"
  [1]=>
  string(39) "Content-Type: text/html; charset=utf-8
"
  [2]=>
  string(18) "Connection: close
"
  [3]=>
  string(12) "Status: 302
"
  [4]=>
  string(60) "X-Powered-By: Phusion Passenger (mod_rails/mod_rack) 2.2.10
"
  [5]=>
  string(34) "X-UA-Compatible: IE=Edge,chrome=1
"
  [6]=>
  string(47) "Location: https://somewebsite.com/54sdf
"
  [7]=>
  string(20) "X-Runtime: 0.006921
"
  [8]=>
  string(132) "Set-Cookie: _sp_session_id=; domain=.superpoints.com; path=/; expires=Mon, 16-Jan-2012 18:08:29 GMT
"
  [9]=>
  string(24) "Cache-Control: no-cache
"
  [10]=>
  string(69) "Server: nginx/0.7.65 + Phusion Passenger 2.2.10 (mod_rails/mod_rack)
"
  [11]=>
  string(1) "
"
  [12]=>
  string(19) "HTTP/1.1 302 Found
"
  [13]=>
  string(39) "Content-Type: text/html; charset=utf-8
"
  [14]=>
  string(18) "Connection: close
"
  [15]=>
  string(12) "Status: 302
"
  [16]=>
  string(60) "X-Powered-By: Phusion Passenger (mod_rails/mod_rack) 2.2.10
"
  [17]=>
  string(34) "X-UA-Compatible: IE=Edge,chrome=1
"
  [18]=>
  string(55) "Location: https://somewebsite.com/no_such_link
"
}

Answer 1

You are relying on a certain header being at a certain position, which it will not always be, and you are also not acounting for the fact the HTTP header keys are case-insensitive.

Try this:

function linkcheck($url) {

    // Do cURL
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_NOBODY, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    $response = explode("\n", curl_exec($ch));
    curl_close($ch);

    // Seperate headers from body
    $parts = explode("\r\n\r\n", $response);

    // Turn headers into associative array
    $head = explode("\r\n", $parts[0]);
    array_shift($head); // Skip response line
    $headers = array();
    foreach ($head as $header) {
        $header = explode(':', $header);
        $key = strtolower(trim(array_shift($header)));
        $val = trim(implode(':', $header));
        if (isset($headers[$key])) {
            if (is_array($headers[$key])) {
                $headers[$key][] = $val;
            } else {
                $headers[$key] = array($headers[$key], $val);
            }
        } else {
            $headers[$key] = $val;
        }
    }

    // If there is no location header, we can't test it
    if (!isset($headers['location'])) {
        echo "No location header";
        return;
    }

    switch ($headers['location']) {
        case "https://somewebsite.com/welcome":
            echo "Active";
            break;
        case "https://somewebsite.com/no_such_link":
            echo "Inactive";
            break;
        default:
            echo "Unknown value";
            break;
    }

}