PayPal IPN with fsockopen returns NULL - php

Question

I'm trying to set up the PayPal IPN on my web application, I copied from PayPal's documentation on an example PHP snippet which is found here.
However, when I'm testing with the PayPal's sandbox, sending an IPN with the simulator which is found here.
Now, when PayPal sends the IPN, I log the actions and data of the IPN, when trying to open an connection with fsockopen, it is NULL when I do var_export on it.
I don't understand why it's not going any further with the code when the fsockopen connection is NULL.
I'm using Codeigniter for my application, and this is the part of the code that fails:
if($this->uri->segment(3) == 'ipn')
{
$error_msg = '';
$error_msg .= " initiated ";
$req = 'cmd=_notify-validate';
$error_msg .= " \n\n req: " . var_export($req, true);
foreach($this->input->post() as $key => $value)
{
$value = urlencode(stripslashes($value));
$req .= "&" . $key . "=" . $value;
}
$error_msg .= " \n\n req: " . var_export($req, true);
$header = '';
$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";
$error_msg .= " \n\n headers: " . var_export($header, true);
$fp = fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 30);
$error_msg .= " \n\n fp: " . var_export($fp, true);
I use $error_msg to log the data, this is an example what is logged:
initiated
req: 'cmd=_notify-validate'
req: 'cmd=_notify-validate&test_ipn=1&payment_type=echeck&payment_date=17%3A30%3A40+Jan+03%2C+2012+PST&payment_status=Completed&address_status=confirmed&payer_status=verified&first_name=John&last_name=Smith&payer_email=buyer%40paypalsandbox.com&payer_id=TESTBUYERID01&address_name=John+Smith&address_country=United+States&address_country_code=US&address_zip=95131&address_state=CA&address_city=San+Jose&address_street=123%2C+any+street&business=seller%40paypalsandbox.com&receiver_email=seller%40paypalsandbox.com&receiver_id=TESTSELLERID1&residence_country=US&item_name=something&item_number=DX4WYSur44CQICgO2lC%2FB10NmdaiPNH3xPZXQNAlfrEqpse0xnime22zaNXDFgbRrOL4Xsz4emkhqFw4JhOSHzCtaHt9%2B0p9p8xW6R71PVbFXNyEVjkPeHNdQm32PJg&quantity=1&shipping=3.04&tax=2.02&mc_currency=USD&mc_fee=0.44&mc_gross=12.34&txn_type=web_accept&txn_id=4014130&notify_version=2.1&custom=xyz123&invoice=abc1234&charset=windows-1252&verify_sign=An5ns1Kso7MWUdW4ErQKJJJ4qi4-AN8d2a.xggmx9Dn4AgHpvPHJHTAp'
headers: 'POST /cgi-bin/webscr HTTP/1.0
Content-Type: application/x-www-form-urlencoded
Content-Length: 969
'
fp: NULL
As you can see $fp is returning NULL on the last line of the logged data. Is there any idea why this is happening?
I can confirm I have OpenSSL enabled and installed on my server:
EDIT: Just tested fsockopen on port 80 to google.com, I still get NULL with no error number or message. So this problems occurs to every URL.
EDIT #2: Tested on my server by doing this:
fsockopen('ssl://www.paypal.com/cgi-bin/webscr', 443, $errno, $errstr, 30)
A PHP Error was encountered
Severity: Warning
Message: fsockopen(): unable to connect to
ssl://www.paypal.com/cgi-bin/webscr:443 (php_network_getaddresses:
getaddrinfo failed: nodename nor servname provided, or not known)

Answer 1

If anyone else is having the same problem, try using HTTPS instead of SSL
$fp = fsockopen ('https://www.paypal.com', 443, $errno, $errstr, 30);
And if your testing on Paypals Sandbox use:
$fp = fsockopen ('https://www.sandbox.paypal.com', 443, $errno, $errstr, 30);

Answer 2

Be careful of $config['csrf_protection'] = TRUE; this will block all external POSTS as they will not come with a CSRF token, I've had this with my paypal IPN before, I needed to enable a crude but effective way to get the callback (in config.php):
if(stripos($_SERVER["REQUEST_URI"],'/paypal') === FALSE) {
// disable CSRF for the /paypal
$config['csrf_protection'] = TRUE;
} else {
$config['csrf_protection'] = FALSE;
}
I'm guessing this could be an issue, you would get null as no data would be captured as CI reviews your $_POST/$_GET vars for security reasons.
If I misunderstood your question and am way off track, just let me know via a comment.

Answer 3

Check List
sandbox url: "https://www.sandbox.paypal.com/cgi-bin/webscr";
like #jakub says CSRF must be disabled for your paypal controller
IPN wont validate on localhost, however you should still get vars back.
var_dump(fsockopen ('https://www.sandbox.paypal.com/', 443, $errno, $errstr, 30));
var_dump($_POST);

Answer 4

The variables $errno and $errstr probably hold the reason for the failure. Echo them out with your error message.