Are there any common mistakes or pitfalls to avoid when using PayPal IPN with PHP?

One common mistake when using PayPal IPN with PHP is not properly verifying the IPN message authenticity. To avoid this pitfall, make sure to verify the IPN message by sending it back to PayPal for validation using cURL. This ensures that the IPN message is genuine and not tampered with. 

// Verify PayPal IPN
$ch = curl_init('https://www.sandbox.paypal.com/cgi-bin/webscr');
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/x-www-form-urlencoded'));
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, "cmd=_notify-validate&" . http_build_query($_POST));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
$response = curl_exec($ch);
curl_close($ch);

if ($response == 'VERIFIED') {
    // IPN message is authentic, process the payment
} else {
    // IPN message is not authentic, log the error
}

Keywords

PayPal IPN PHP errors debugging validation

Related Questions