PayPal HTTP 1.1 Update for IPN/PDT

// File: wp-checkout/wp-checkout.php
// Line: Approximately line #2848
// Changes: 2 small changes as noted below

$header = "";
$header .= "POST /cgi-bin/webscr HTTP/1.1" . "\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded" . "\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$ppurl = ($this -> get_option('pp_sandbox') == "Y") ? 'www.sandbox.paypal.com' : 'www.paypal.com';
$fp = fsockopen($ppurl, 80, $errno, $errstr, 30);

//.....several lines of code here

if (!$fp) {
    $message = __('An HTTP error has occurred', $this -> plugin_name);
} else {
    fputs($fp, $header . $req);

    while (!feof($fp)) {
        $res = null;
        $res = trim(fgets($fp, 1024));