PHP Cache issue when posting data using fsockopen - php

Question

I am using Mailchimp api 1.3 php wrapper. The problem is that a server where my customer hosts a site will cache response, it won't even make api call. The exact the same code works with me and other customers:
$api = new MCAPI($apiKey);
$doubleOptin = false;
$mergeVar = array(
'FNAME' => '',
'LNAME' => ''
);
$api->listSubscribe($listId, $email, $mergeVar, 'html', $doubleOptin);
print_r($api);
method listSubscribe() calls method callServer where I guess is the problem:
$payload = "POST " . $this->apiUrl["path"] . "?" . $this->apiUrl["query"] . "&method=" . $method . " HTTP/1.0\r\n";
$payload .= "Host: " . $host . "\r\n";
$payload .= "User-Agent: MCAPI/" . $this->version ."\r\n";
$payload .= "Content-type: application/x-www-form-urlencoded\r\n";
$payload .= "Content-length: " . strlen($post_vars) . "\r\n";
$payload .= "Connection: close \r\n\r\n";
$payload .= $post_vars;
ob_start();
if ($this->secure){
$sock = fsockopen("ssl://".$host, 443, $errno, $errstr, 30);
} else {
$sock = fsockopen($host, 80, $errno, $errstr, 30);
}
if(!$sock) {
$this->errorMessage = "Could not connect (ERR $errno: $errstr)";
$this->errorCode = "-99";
ob_end_clean();
return false;
}
$response = "";
fwrite($sock, $payload);
stream_set_timeout($sock, $this->timeout);
$info = stream_get_meta_data($sock);
while ((!feof($sock)) && (!$info["timed_out"])) {
$response .= fread($sock, $this->chunkSize);
$info = stream_get_meta_data($sock);
}
var_dump($response); exit;
Does anybody have any idea why fsockopen and fwrite never sends call to Mailchimp? Weird thing is that I can actually read $response, but it is always the same from cache.

Answer 1

If the code works for you and there is some query caching then you could try to add a timestamp to the request.
"&time=".time()
This way you always have a "fresh" request.