Where to find the callback php files for gateways?

[timnboys]

I am trying to make a mock example for this request I submitted:

https://requests.blesta.com/topic/chargeback-watching-plugin

but do not know where the callback for the paypal gateway is at?

[mrrsm]

Aren't all the gateway callbacks more or less the same

Configure::set("Blesta.gw_callback_url", "http" . (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != "off" ? "s" : "") . "://" . (isset($_SERVER['HTTP_HOST']) ? $_SERVER['HTTP_HOST'] : "localhost") . WEBDIR . "callback/gw/");

Specifically for paypal the notify url is built

'notify_url' => Configure::get('Blesta.gw_callback_url')
                . Configure::get('Blesta.company_id') . '/paypal_payments_standard/?client_id='
                . $this->ifSet($contact_info['client_id']),