curl through proxy returns no content

Question

I'm working on a PHP script right now which sends requests to our school's servers to get real-time information about class sizes for different courses. The script runs perfectly fine when I don't use a proxy, returning a string full of course numbers and available seats. However, I want to make this a service for the students, and I'm afraid that if I make too many requests my ip will get blocked. So I'm attempting to do this through a proxy, with no success. As soon as I add the CURLOPT_HTTPPROXYTUNNEL and CURLOPT_PROXY fields to my requests nothing gets returned. I'm not even sure how to troubleshoot it at this point since I'm not getting an error message of any kind. Does anyone know what's going on or how to at least troubleshoot it?

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$proxy = explode(':', $proxy);
curl_setopt($ch, CURLOPT_PROXY, $proxy[0]);
curl_setopt($ch, CURLOPT_PROXYPORT, $proxy[1]);
curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL, 1);
curl_setopt($ch, CURLOPT_COOKIEFILE, 'tempcookie.txt');
curl_setopt($ch, CURLOPT_COOKIEJAR, 'tempcookie.txt');
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_REFERER, $ref);
$exec = curl_exec($ch);

echo curl_error($ch);
print_r(curl_getinfo($ch));
echo $exec;

Proxy used for tests: 75.147.173.215:8080

Answer 1

I use the following code if I have to use a proxy with curl:

$proxy = "127.0.0.1:8080"; // or something like that

if($proxy !== null){

    // no need to specify PROXYPORT again
    curl_setopt($ch, CURLOPT_PROXY, $proxy);

    // to make the request go through as though proxy didn't exist
    curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL, 0);

}

Answer 2

You can set CURLOPT_STDERR and CURLOPT_VERBOSE curl options to save your errors in a file. Also, you may use curl_error() function. BTW, by default, curl should show all errors in STDERR.

Besides, for general check, you can simply specify selected proxy in you browser configuration properties, try to open specific service in browser and see, whether correct response is returned.

UPDATE:

CURLOPT_HTTPPROXYTUNNEL is used to make curl call CONNECT HTTP method when requesting proxy server (see here for details). I tested code without this option - it worked successfully.

Code I used:

$proxy = "75.147.173.215:8080";
$proxy = explode(':', $proxy);
$url = "http://google.com";

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_PROXY, $proxy[0]);
curl_setopt($ch, CURLOPT_PROXYPORT, $proxy[1]);
curl_setopt($ch, CURLOPT_HEADER, 1);

$exec = curl_exec($ch);

echo curl_error($ch);
print_r(curl_getinfo($ch));
echo $exec;