codeigniter-paypal-ipn is a CodeIgniter library for working with the PayPal IPN (Instant
Payment Notification) service. The library acts as a listener for the PayPal IPN service
and logs the orders to your database using either Doctrine or CodeIgniter active record.

This library focuses on the “post-payment” workflow, i.e. the processing required once
the payment has been made and PayPal has posted an Instant Payment Notification call to
the IPN listener (aka your CodeIgniter IPN controller).

This library handles:

• Validating the IPN call
• Logging the IPN call
• Extracting the order and line item information from the IPN call
• Interpreting PayPal’s payment status
• Storing the order and line item in the database

Note that this library currently supports the web_accept and cart transaction types; order
refunds are not currently supported.

All pre-payment functionality (e.g. posting the checkout information to PayPal) and custom
post-payment workflow (e.g. sending emails) is left as an exercise to the reader.

There are two versions supplied: one using CodeIgniter’s modified version of the Active
Record Database Pattern, and one using Doctrine (tested with 1.2.3). For the second option
you might find the CodeIgniter guide Using Doctrine with CodeIgniter helpful background.

To create the MySQL tables required by codeigniter-paypal-ipn, run the SQL file found
in the common/sql folder against your db.

Download all of the remaining files from the common folder and deploy them into your CodeIgniter
installation following the same folder structure as found in GitHub. Then choose between
the activerecord and doctrine1.2 folder, and deploy those files into your CodeIgniter
installation as well.

Finally, update your sandbox and production variables as found in config/paypal_ipn.php

An example of how to use codeigniter-paypal-ipn can be found in controllers/example.php

This library is inspired by:

• Ran Aroussi’s PayPal_Lib for CodeIgniter (which I used for some time before writing my own)
• Peter Butler’s original PayPal IPN Controller for CakePHP (for giving me the initial ideas around in-database storage of the orders)
• @webtechnik’s CakePHP-PayPal-IPN Plugin (for the tidy configuration settings)

The author Alex Dean does not accept any liability for any processing errors made by
codeigniter-paypal-ipn, or any financial losses incurred through its use.

In particular, this library does not fulfil the PayPal IPN requirement to “verify that the
payment amount actually matches what you intend to charge. Although not technically an IPN
issue, if you do not encrypt buttons, it is possible for someone to capture the original
transmission and change the price. Without this check, you could accept a lesser payment
than what you expected.” (This verification step is out of scope for this library because
it would require integration with your product catalogue.)

Additionally this library does not properly handle refunds. Typically refunds are stored as
a new order line in ipn_orders with a negative balance, but even this is not 100% predicatable.

codeigniter-paypal-ipn is copyright © 2011 Alexander Dean, [email protected]

codeigniter-paypal-ipn is free software: you can redistribute it and/or modify it under the
terms of the GNU Affero General Public License as published by the Free Software Foundation,
either version 3 of the License, or (at your option) any later version.

codeigniter-paypal-ipn is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with
codeigniter-paypal-ipn. If not, see http://www.gnu.org/licenses/.