Paypal IPN not Verified or Invalid - php

Question

Hopefully someone will be able to help me or point me in the right direction. I have set up a Paypal IPN listener but don't seem to be getting any response (verified / invalid) back from the paypal after confirming the payment with paypal
I know the code works to some degree as the IPN History page confirms that a response was received back from the listener so paypal does not attempt to resend the message. If I place a code snippet to insert into my database outside of the verified/invalid if statement it works fine. It just does not do anything when I place the same code snippet inside the verified / invalid loop.
The PHP code I am using for the listener is as follows:
Hopefully someone will be able to help me or point me in the right direction. I have set up a Paypal IPN listener but
don't seem to be getting any response (verified / invalid) back from the paypal after confirming the payment with paypal
I know the code works to some degree as the IPN History page confirms that a response was received back from the listener
so paypal does not attempt to resend the message. If I place a code snippet to insert into my database outside of the verified/invalid
if statement it works fine. It just does not do anything when I place the same code snippet inside the verified / invalid loop.
The PHP code I am using for the listener is as follows:
<?php
// STEP 1 - be polite and acknowledge PayPal's notification
header('HTTP/1.1 200 OK');
// STEP 2 - create the response we need to send back to PayPal for them to confirm that it's legit
$resp = 'cmd=_notify-validate';
foreach ($_POST as $parm => $var)
{
$var = urlencode(stripslashes($var));
$resp .= "&$parm=$var";
}
// STEP 3 - Extract the data PayPal IPN has sent us, into local variables
$record_id = $_POST['custom'];
$item_name = $_POST['item_name'];
$item_number = $_POST['item_number'];
$payment_status = $_POST['payment_status'];
$payment_amount = $_POST['mc_gross'];
$payment_currency = $_POST['mc_currency'];
$txn_id = $_POST['txn_id'];
$receiver_email = $_POST['receiver_email'];
$payer_email = $_POST['payer_email'];
// STEP 4 - Get the HTTP header into a variable and send back the data we received so that PayPal can confirm it's genuine
$httphead = "POST /cgi-bin/webscr HTTP/1.1\r\n";
$httphead .= "Content-Type: application/x-www-form-urlencoded\r\n";
$httphead .= "Content-Length: " . strlen($resp) . "\r\n\r\n";
// Now create a ="file handle" for writing to a URL to paypal.com on Port 443 (the IPN port)
$errno ='';
$errstr='';
//$fh = fsockopen ('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30);
$fh = fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 30);
// STEP 5 - Nearly done. Now send the data back to PayPal so it can tell us if the IPN notification was genuine
if (!$fh) {
}
else {
fputs ($fh, $httphead . $resp);
while (!feof($fh))
{
$readresp = fgets ($fh, 1024);
if (strcmp ($readresp, "VERIFIED") == 0)
{
}
else if (strcmp ($readresp, "INVALID") == 0)
{
}
}
fclose ($fh);
}
?>