creating action with paypal ipn - function

Question

This is my first time attempting to use paypal ipn. I am an amateur coder for sure. I have developed a user/subscriber site and I am wanting to finalize the paypal subscriber payments.
I have a number of questions but I know I should narrow it down to 1.
I understand ipn as sending a message to a page on my site. (I may be wrong). I am going to assume that would be the IPN handler URL. (?)
Does the IPN actually hit the page and create an action?
I would like that message (or loading of the page) to call a function which inserts in my database.
Here is my Listener...ipnverify.php
<?php require(Config::get('URL').'/paypalipn/PaypalIPN.php');
use PaypalIPN;
$ipn = new PayPalIPN();
$ipn->useSandbox();$verified = $ipn->verifyIPN();$name = $_POST['custom'];
if ($name==1) {
function updatePaypalTest()
{
$database = DatabaseFactory::getFactory()->getConnection();
$sql = "INSERT INTO paypal_test (name) VALUES('1')";
$query = $database->prepare($sql);
$query->execute();
}
updatePaypalTest();
header("HTTP/1.1 200 OK");
?>
And then the other file from github...PaypalIPN.php
<?php
class PaypalIPN
{
private $use_sandbox = true;
private $use_local_certs = false;
/*
* PayPal IPN postback endpoints
*/
const VERIFY_URI = 'https://ipnpb.paypal.com/cgi-bin/webscr';
const SANDBOX_VERIFY_URI = 'https://ipnpb.sandbox.paypal.com/cgi-bin/webscr';
/*
* Possible responses from PayPal after the request is issued.
*/
const VALID = 'VERIFIED';
const INVALID = 'INVALID';
/**
* Sets the IPN verification to sandbox mode (for use when testing,
* should not be enabled in production).
* #return void
*/
public function useSandbox()
{
$this->use_sandbox = true;
}
/**
* Determine endpoint to post the verification data to.
* #return string
*/
public function getPaypalUri()
{
if ($this->use_sandbox) {
return self::SANDBOX_VERIFY_URI;
} else {
return self::VERIFY_URI;
}
}
/**
* Verification Function
* Sends the incoming post data back to paypal using the cURL library.
*
* #return bool
* #throws Exception
*/
public function verifyIPN()
{
if ( ! count($_POST)) {
throw new Exception("Missing POST Data");
}
$raw_post_data = file_get_contents('php://input');
$raw_post_array = explode('&', $raw_post_data);
$myPost = [];
foreach ($raw_post_array as $keyval) {
$keyval = explode('=', $keyval);
if (count($keyval) == 2) {
// Since we do not want the plus in the datetime string to be encoded to a space, we manually encode it.
if ($keyval[0] === 'payment_date') {
if (substr_count($keyval[1], '+') === 1) {
$keyval[1] = str_replace('+', '%2B', $keyval[1]);
}
}
$myPost[$keyval[0]] = urldecode($keyval[1]);
}
}
// Build the body of the verification post request, adding the _notify-validate command.
$req = 'cmd=_notify-validate';
$get_magic_quotes_exists = false;
if (function_exists('get_magic_quotes_gpc')) {
$get_magic_quotes_exists = true;
}
foreach ($myPost as $key => $value) {
if ($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) {
$value = urlencode(stripslashes($value));
} else {
$value = urlencode($value);
}
$req .= "&$key=$value";
}
// Post the data back to paypal, using curl. Throw exceptions if errors occur.
$ch = curl_init($this->getPaypalUri());
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
curl_setopt($ch, CURLOPT_SSLVERSION, 6);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
// This is often required if the server is missing a global cert bundle, or is using an outdated one.
if ($this->use_local_certs) {
curl_setopt($ch, CURLOPT_CAINFO, __DIR__ . "/cert/cacert.pem");
}
curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
curl_setopt($ch, CURLOPT_HTTPHEADER, ['Connection: Close']);
$res = curl_exec($ch);
$info = curl_getinfo($ch);
$http_code = $info['http_code'];
if ($http_code != 200) {
throw new Exception("PayPal responded with http code $http_code");
}
if ( ! ($res)) {
$errno = curl_errno($ch);
$errstr = curl_error($ch);
curl_close($ch);
throw new Exception("cURL error: [$errno] $errstr");
}
curl_close($ch);
// Check if paypal verfifes the IPN data, and if so, return true.
if ($res == self::VALID) {
return true;
} else {
return false;
}
}
}
Please help me understand what I am missing. Is there a way that I can call my function from the ipn message?