Paypal SandBox IPN always returns INVALID

Question

As mentioned in one of the comments in an answer below, I tried following this tutorial. So now I have the following:

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The ipn.php file:

Answer 1

I am not sure what is exactly wrong right now with your code, but I was strugling wuth the same while ago and my fixes was to add HOST in the header and host have to be www.paypal.com. I used fsockopen method and work fine now.

In Curl I had a problem before with ssl. And solution was to put those lines:

curl_setopt($curl, CURLOPT_COOKIEJAR, dirname(__FILE__) . "/cookies.txt");
curl_setopt($curl, CURLOPT_COOKIEFILE, dirname(__FILE__) . "/cookies.txt");

where of course file cookies.txt have to exists. and more over I had to run one connection to page to get session data and later send post data.

Below is a header what is working fine for me with fsockopen method

$header = "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Host: www.paypal.com\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";