Hey all...

I'm trying to figure out how to use PayPal's IPN and I've run into a wall.

I want a buyer to be forwarded to a success page after making a purchase, and I want that page to show the details of their transaction. I choose IPN instead of the PDT because I also want to do some other behind the scenes stuff with their data.

Anyway, here's the code I'm using -- I'm testing in sandbox mode -- but it returns "FAIL" every time.

$req = 'cmd=_notify-validate';
foreach ($_POST as $key => $value) {
$value = urlencode(stripslashes($value));
$req .= "&$key=$value";
}
// post back to PayPal system to validate
$header = "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";

$fp = fsockopen ('www.sandbox.paypal.com', 80, $errno, $errstr, 30);

if (!$fp) {
// HTTP ERROR
} else {
fputs ($fp, $header . $req);
while (!feof($fp)) {
$res = fgets ($fp, 1024);
if (strcmp ($res, "VERIFIED") == 0) {

// PAYMENT VALIDATED & VERIFIED!

echo "Validated!";

}

else if (strcmp ($res, "INVALID") == 0) {

// PAYMENT INVALID & INVESTIGATE MANUALY!

echo "Invalid!";

}
}
fclose ($fp);
}