cURL Checking for Timeout

I know how to set the timeout in cURL but I want to alert the u开发者_运维技巧ser that the request timed out.

I have created an ajax script that allows the user to request data from various insurance sites and aggregate into a list. If any of the insurance sites fail to respond within a certain time I want to alert the user that the current quote from that company is not available at the moment.

Does cURL return anything to signal a timeout?

curl_errno() returns 28 if the operation timed out. See http://curl.haxx.se/libcurl/c/libcurl-errors.html for other error codes.

Or another solution that can cover even more cases (server timed out, server errored out with a blank page) is to check if your get_url function result is different that "" or FALSE.

Example of get_url function :

function get_url($url)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_TIMEOUT, 5);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
    $tmp = curl_exec($ch);
    curl_close($ch);
    return $tmp;
}