Track user activity when recurring payment occurs using paypal subscribe button - php

Question

I have a working IPN script. It is updating the data correctly in database according to the logged in user. So, Once the payment is successfully made user account will be upgraded as a paid member. And since i am using a paypal subscribe button. So, from the next month billing process will occur automatically.
So, here what i think(I am not sure), Paypal will not interact with my IPN script stored in my server.
So, My question is :-
If my assumption about IPN script is correct then how could i track which user has made a payment for the next billing cycle? (I don't want to be involved with manual work like tracking user payment information from my Paypal merchant account. I just want to do it through a script. So, once the subscription amount has been deducted from user Paypal account his account on my website will be upgraded as a paid member.)
For the reference what exactly i wanted to update through my ipn script. Below is my IPN script.
<?php
// STEP 1: Read POST data
// reading posted data from directly from $_POST causes serialization
// issues with array data in POST
// reading raw POST data from input stream instead.
$raw_post_data = file_get_contents('php://input');
$raw_post_array = explode('&', $raw_post_data);
$myPost = array();
foreach ($raw_post_array as $keyval) {
$keyval = explode ('=', $keyval);
if (count($keyval) == 2)
$myPost[$keyval[0]] = urldecode($keyval[1]);
}
// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-validate';
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";
}
// STEP 2: Post IPN data back to paypal to validate
$ch = curl_init('https://www.sandbox.paypal.com/cgi-bin/webscr');
curl_setopt($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_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
// In wamp like environments that do not come bundled with root authority certificates,
// please download 'cacert.pem' from "http://curl.haxx.se/docs/caextract.html" and set the directory path
// of the certificate as shown below.
// curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/cacert.pem');
if( !($res = curl_exec($ch)) ) {
// error_log("Got " . curl_error($ch) . " when processing IPN data");
curl_close($ch);
exit;
}
curl_close($ch);
// STEP 3: Inspect IPN validation result and act accordingly
if (strcmp ($res, "VERIFIED") == 0) {
// check whether the payment_status is Completed
// check that txn_id has not been previously processed
// check that receiver_email is your Primary PayPal email
// check that payment_amount/payment_currency are correct
// process payment
// assign posted variables to local variables
$item_name = $_POST['item_name'];
$item_name=strip_tags($item_name);
$item_number = strip_tags($_POST['item_number']);
$payment_status = strip_tags($_POST['payment_status']);
$payment_amount = strip_tags($_POST['mc_gross']);
$payment_currency = strip_tags($_POST['mc_currency']);
$txn_id = strip_tags($_POST['txn_id']);
$user_id=strip_tags($_POST['custom']);
$receiver_email = strip_tags($_POST['receiver_email']);
$payer_email = strip_tags($_POST['payer_email']);
//if(strcmp($receiver_email, "h_1356964205_per#gmail.com") == 0)
//{
/*if($payment_status != "Completed")
{
$msg="Transaction with id ".$txn_id." status is not completed..";
mail("support#example.com","Transaction with the same id already exists in database.",$msg,"From:admin#leadstool.net");
exit();
}*/
include_once('connection.php');
//$user_id=getfield('id');
// Query to check the duplicate transaction id.
$query="SELECT `User_id` FROM `transaction` WHERE `Transaction_id`='".mysql_real_escape_string($txn_id)."'";
if($query_run=mysql_query($query))
{
$num=mysql_num_rows($query_run);
if($num == 0)
{
// Query to check the number of times for subscription.
$query="SELECT `Transaction_id` FROM `transaction` WHERE `User_id`='".mysql_real_escape_string($user_id)."'";
if($query_run=mysql_query($query))
{
$num=mysql_num_rows($query_run);
if($num>=1)
{
$type_of_subscription=2;// This 2 will denote the user is rnewing his account
} else {
$type_of_subscription=1;// Here 1 is denoting that user has subscribed for the 1st time.
}
$query="SELECT `B_ad_no_paid_user`,`T_ad_no_paid_user` FROM `WebsiteContent` WHERE `Creator_id`='1' ORDER BY `Date_of_update` DESC LIMIT 1";
if($query_run=mysql_query($query))
{
while($rows=mysql_fetch_array($query_run))
{
$banner_ad_limit=$rows['B_ad_no_paid_user'];
$text_ad_limit=$rows['T_ad_no_paid_user'];
}
}
}// Query to check the number of times for subscription ends here.
//Query to insert the transaction details in database.
$query="INSERT INTO `transaction` VALUES('".$txn_id."','".$user_id."','".$payment_amount."','".$type_of_subscription."','".$payment_status."','1','".$payer_email."',now())";
if($query_run=mysql_query($query))
{
$query="UPDATE `user` SET `User_type`='1', `Banner_ad_limit`='".$banner_ad_limit."', `Text_ad_limit`='".$text_ad_limit."' WHERE `id`='".mysql_real_escape_string($user_id)."'";
if($query_run=mysql_query($query))
{
$msg="Thank you for subscribing to our service. Your Transaction Id is $txn_id.";
mail("$payer_email","Subscription confirmation mail",$msg,"From:admin#example.com");
} else {
$msg="Thank you! Your transaction is successful with transaction id:- $txn_id. But we are unable to upgrade your profile right now. Please contact admin to resolve the problem.";
mail("$payer_email","Subscription confirmation mail",$msg,"From:admin#example.com");
}
} else {
$msg="For Transaction with id ".$txn_id." failed to update in database.";
mail("support#example.com","Unable to update the details in database.",$msg,"From:admin#example.com");
exit();
}
// Query to insert data in database ends here.
} else {
$msg="Transaction with id $txn_id already exists in database. Admin please verify the details manually and contact the user. Email id of user is: $payer_email";
mail("support#example.com","Transaction with the same id already exists in database.",$msg,"From:admin#example.com");
exit();
}// Query to check the duplicate transaction id ends here.
}
//} else {
//$msg="Investigate the reason why the registered email id with paypal does not matched with this id $receiver_email";
//mail("support#example.com","Receiver email address do not matched",$msg,"From:admin#example.com");
//exit();
//}
} else if (strcmp ($res, "INVALID") == 0) {
// log for manual investigation
$msg="Dear administrator please verify the reason why the transaction failure occures. The details is:- $res";
mail("support#example.com","IPN interaction was not verified.",$msg,"From:admin#example.com");
exit();
}
?>

Answer 1

This is possible using the IPN and notify_url.
Here is a good tutorial:
http://www.techrepublic.com/article/handling-recurring-payments-with-paypal-subscriptions-and-ipn/5331883