PayPal IPN Verifier

A PayPal Instant Payment Notification (IPN) verifier class for PHP 5.

Use the IpnVerifier class in your IPN script to handle the encoding of POST data, post back to PayPal, and parsing of the response from PayPal.

This class was based on (and is almost API-compatible with) Quixotix/PHP-PayPal-IPN. See below for differences and tips for porting your code.

Features

• Supports live and sandbox environments.
• Verifies an HTTP "200" response status code from the PayPal server.
• Get detailed plain text reports of the entire IPN using the getTextReport() method for use in emails and logs to administrators.
• Throws various exceptions to differentiate between common errors in code or server configuration versus invalid IPN responses.

Differences from Quixotix/PHP-PayPal-IPN

• Always verifies IPNs using SSL.
• Always uses cURL (no fsockopen support).
• PSR-2 compliant coding style.

Getting Started

This code is intended for web developers. You should understand how the IPN process works conceptually and you should understand when and why you would be using IPN. Reading the PayPal Instant Payment Notification Guide is a good place to start.

You should also have a PayPal Sandbox Account with a test buyer account and a test seller account. When logged into your sandbox account there is an IPN simulator under the 'Test Tools' menu which you can used to test your IPN listener.

Once you have your sandbox account set up, you simply create a PHP script that will be your IPN listener. In that script, use the IpnVerifier() class as shown below.

<?php
use Toolani\Payment\Paypal\IpnVerifier;

// If you're doing this for real, autoloading would be better
include("/path/to/Toolani/Payment/Paypal/IpnVerifier.php");

$verifier = new IpnVerifier($useSandbox = true);

try {
    $verified = $verifier->verify($_POST);
} catch (Exception $e) {
    // fatal error trying to process IPN.
    exit(1);
}

if ($verified) {
    // IPN response was "VERIFIED"
} else {
    // IPN response was "INVALID"
}

// Verification status is available as a string, too. See table below
$status = $verifier->getVerificationStatusString();

Logging

The IpnVerifier constructor optionally accepts a PSR-3 compliant logger object as its second parameter.

If provided, this will be used to log some basic info about each IPN and details of any errors during verification.

Verification Status Strings

These are the possible status that may be returned by getVerificationStatusString. In normal operation, only 'VERIFIED' and 'INVALID' would be expected. Other statuses indicate errors.

Status	Description
VERIFIED	IPN verified OK
INVALID	PayPal reports that IPN is invalid
UNKNOWN	We didn't get as far as trying to verify
ERROR	Tried to verify and something went wrong
NO_DATA	No data was provided to be verified
IPN_TIMEOUT	Verification request timed out

Quixotix/PHP-PayPal-IPN compatibility

It should be straightforward to port scripts using the PHP-PayPal-IPN class to use IpnVerifier instead, and a processIpn() method is provided to ease this.

The usage example above is directly equivalent to the example given in the PHP-PayPal-IPN documentation.

Things to be aware of:

• Sandbox configuration is now done via a constructor argument, rather than a public property, though the useSandbox property remains public (for the moment).
• There are no options for configuring cURL, SSL will always be used.
• The verify method requires that you explicitly provide the array of POSTed data. PHP-PayPal-IPN's processIpn did not and would automagically use $_POST if given no data. A processIpn method is thus provided, which mimics the old behaviour. Note: verify is the preferred method for verifying IPNs and processIpn should be considered deprecated and may be removed in future versions of this class.

Example Report

Here is an example of a report returned by the getTextReport() method. Create your own reports by extending the IpnVerifier class or by accessing the data directly in your ipn script.

--------------------------------------------------------------------------------
[09/09/2011 8:35 AM] - https://www.sandbox.paypal.com/cgi-bin/webscr (curl)
--------------------------------------------------------------------------------
HTTP/1.1 200 OK
Date: Fri, 09 Sep 2011 13:35:39 GMT
Server: Apache
X-Frame-Options: SAMEORIGIN
Set-Cookie: c9MWDuvPtT9GIMyPc3jwol1VSlO=Ch-NORlHUjlmbEm__KG9LupR4mfMfQTkx1QQ6hHDyc0RImWr88NY_ILeICENiwtVX3iw4jEnT1-1gccYjQafWrQCkDmiykNT8TeDUg7R7L0D9bQm47PTG8MafmrpyrUAxQfst0%7c_jG1ZL6CffJgwrC-stQeqni04tKaYSIZqyqhFU7tKnV520wiYOw0hwk5Ehrh3hLDvBxkpm%7cYTFdl0w0YpEqxu0D1jDTVTlEGXlmLs4wob2Glu9htpZkFV9O2aCyfQ4CvA2kLJmlI6YiXm%7c1315575340; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: cookie_check=yes; expires=Mon, 06-Sep-2021 13:35:40 GMT; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: navcmd=_notify-validate; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: navlns=0.0; expires=Thu, 04-Sep-2031 13:35:40 GMT; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: Apache=10.72.109.11.1315575339707456; path=/; expires=Sun, 01-Sep-41 13:35:39 GMT
X-Cnection: close
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8

VERIFIED
--------------------------------------------------------------------------------
test_ipn                 1
payment_type             instant
payment_date             06:34:51 Sep 09, 2011 PDT
payment_status           Completed
address_status           confirmed
payer_status             verified
first_name               John
last_name                Smith
payer_email              buyer@paypalsandbox.com
payer_id                 TESTBUYERID01
address_name             John Smith
address_country          United States
address_country_code     US
address_zip              95131
address_state            CA
address_city             San Jose
address_street           123, any street
business                 seller@paypalsandbox.com
receiver_email           seller@paypalsandbox.com
receiver_id              TESTSELLERID1
residence_country        US
item_name                something
item_number              AK-1234
quantity                 1
shipping                 3.04
tax                      2.02
mc_currency              USD
mc_fee                   0.44
mc_gross                 12.34
mc_gross_1               9.34
txn_type                 web_accept
txn_id                   51991334
notify_version           2.1
custom                   xyz123
charset                  windows-1252
verify_sign              Ah5rOpfPGo5g6FNg95DMPybP51J5AUEdXS1hqyRAP6WYYwaixKNDgQRR