payment.php

<?php
// Database variables
$host = "localhost"; //database location
$user = ""; //database username
$pass = ""; //database password
$db_name = ""; //database name

// PayPal settings
$paypal_email = '';
$return_url = '';
$cancel_url = '';
$notify_url = '';

$item_name = '';
$item_amount = 25.00;


//Database Connection
$link = mysql_connect($host, $user, $pass);
mysql_select_db($db_name);

// Check if paypal request or response
if (!isset($_POST["txn_id"]) && !isset($_POST["txn_type"])){
	// Request from step 3
}else{

	// Response from Paypal

	// read the post from PayPal system and add 'cmd'
	$req = 'cmd=_notify-validate';
	foreach ($_POST as $key => $value) {
		$value = urlencode(stripslashes($value));
		$value = preg_replace('/(.*[^%^0^D])(%0A)(.*)/i','${1}%0D%0A${3}',$value);// IPN fix
		$req .= "&$key=$value";
	}

	// assign posted variables to local variables
	$data['item_name']			= $_POST['item_name'];
	$data['item_number'] 		= $_POST['item_number'];
	$data['payment_status'] 	= $_POST['payment_status'];
	$data['payment_amount'] 	= $_POST['mc_gross'];
	$data['payment_currency']	= $_POST['mc_currency'];
	$data['txn_id']				= $_POST['txn_id'];
	$data['receiver_email'] 	= $_POST['receiver_email'];
	$data['payer_email'] 		= $_POST['payer_email'];
	$data['payer_name'] 		= $_POST['first_name']." ".$_POST['last_name'];
	$data['custom'] 			= $_POST['custom'];

	// post back to PayPal system to validate
	$header = "POST /cgi-bin/webscr HTTP/1.0\r\n";
	$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
	$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";

	$fp = fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 30);

	if (!$fp) {
	mail('[email protected]', 'Error With Purchase', $errno.$errstr);
	} else {

		fputs ($fp, $header . $req);
		while (!feof($fp)) {
			$res = fgets ($fp, 1024);
			if (strcmp ($res, "VERIFIED") == 0) {

				// Validate payment (Check unique txnid & correct price)
				$valid_txnid = check_txnid($data['txn_id']);
				$valid_price = check_price($data['payment_amount'], $data['item_number']);
				// PAYMENT VALIDATED & VERIFIED!
				if($valid_txnid && $valid_price){
					$orderid = updatePayments($data);
					if($orderid){
						// Payment has been made & successfully inserted into the Database
						
						
					}else{
						// Error inserting into DB
						// E-mail admin or alert user
						
					}
				}else{
					// Payment made but data has been changed
					// E-mail admin or alert user
				}

			}else if (strcmp ($res, "INVALID") == 0) {
				// PAYMENT INVALID & INVESTIGATE MANUALY!
				// E-mail admin or alert user
			}
		}
	fclose ($fp);
	}
}
?>