paypal invalid ipn

[eluser]spheroid[/eluser]
Let's say you have a controller "store.php". Within the function "index()", you put together the Paypal form to display in the browser which contains:

Code:

$this->paypal_lib->add_field('notify_url', site_url('store/ipn'));

Once the user is sent to Paypal and completes his info, Paypal returns to the URL at your site like http://mysite.dev/store/ipn. When using the sandbox look at the URL returned in your browser (you'll likely see extra variables it posts back to your "notify_url".

In your store.php controller, your function "ipn()" has the line:

Code:

if ($this->paypal_lib->validate_ipn())

So it goes to the library function "validate_ipn" and then reads the response received from Paypal (i.e. the extra variables in the URL) or from the $_POST values. Does this make sense?