integrate paypal payments advanced with curl in php

Question

I need to integrate paypal payments advanced in a website. I have configured the required settings on manager.paypal.com.

Now I am making secure http request using curl. But curl_exec doesn't returns anything. Here is my code. I have confirmed that all the variables have correct values.

$ch=curl_init();
curl_setopt($ch, CURLOPT_URL, $pf_host_addr);
curl_setopt($ch, CURLOPT_RETURNTRANSFER , TRUE);
curl_setopt($ch,CURLOPT_POST,TRUE);
curl_setopt($ch,CURLOPT_POSTFIELDS, $postdata);
$resp=curl_exec($ch);

if(!$resp)
{
    return "<p>Failed</p>";
}

I get failed as output.

Answer 1

Official documentation on this page is quite helpful

https://www.x.com/developers/paypal/documentation-tools/quick-start-guides/paypal-payments-advanced-hosted-pages