TLDR

Drop-in replacement for paypal-ipn@3.0.0.

Why?

The original version, paypal-ipn, could not verify IPNs with characters that are already escaped by PayPal, like %E1 (á) and %E9 (é).

PayPal IPN Verification

A simple NodeJS package for verifying PayPal IPN messages.

Installation

$ npm install pp-ipn

Usage

There is only one function, verify, which is used to verify any IPN messages you receive:

ipn.verify(ipn_params, [settings], callback);

ipn_params is the dictionary of POST values sent to your IPN script by PayPal. Don't modify the dict in any way, just pass it directly to ipn.verify to check if the IPN message is valid.

Example code:

// Must respond to PayPal IPN request with an empty 200 first
// If using Express, uncomment the following:
// res.send(200);

var ipn = require('pp-ipn');

ipn.verify(params, function callback(err, msg) {
  if (err) {
    console.error(err);
  } else {
    // Do stuff with original params here

    if (params.payment_status == 'Completed') {
      // Payment has been confirmed as completed
    }
  }
});

//You can also pass a settings object to the verify function:
ipn.verify(params, {'allow_sandbox': true}, function callback(err, mes) {
  //The library will attempt to verify test payments instead of blocking them
});

Note that all the package does is confirm that the IPN message is valid. After this, you will still need to make some more checks:

Confirm that the payment_status is Completed.
Use the transaction ID to verify that the transaction has not already been processed, which prevents duplicate transactions from being processed.
Validate that the receiver's email address is registered to you.
Verify that the price, item description, and so on, match the transaction on your website.

You can find more information on the PayPal documentation for IPN.

Settings

Optional settings:

{
  'allow_sandbox': false
}

allow_sandbox

If this is true, the library will attempt to verify sandbox requests at PayPal's sandbox URL.

If this is false, the library will callback with an error without checking PayPal. (This is the default value.)

You should set this to false on production servers.

The callback

The callback has two parameters, err and msg.

If err is null then the IPN is valid and you can continue processing the payment. msg is always VERIFIED then.

In case IPN was invalid or the http request failed err holds the Error object.

Express

pp-ipn works fine with Express or any other web framework.

All you need to do is pass in the request parameters to ipn.verify.

In Express, the request parameters are in req.body:

ipn.verify(req.body, callback_function);

Testing

Tests are written in Node Tap, run them like this:

npm t

If you would like a more fancy report:

npm test -- --cov --coverage-report=lcov

sr-scott/pp-ipn