php paypal Integration

Here is the code that would help you to implement paypal in your php website.It is a simple code that you could use in your site and make a paypal run shopping cart easily.

Create an account in sandbox.paypal.com and create a buyer and seller account in it then do as follows:

1. Creating paypal form

<form method="post" action="https://www.sandbox.paypal.com/cgi-bin/webscr" target="paypal">
    <input type="hidden" name="cmd" value="_cart"> <!-- if paypal cart -->
    <input type="hidden" name="cmd" value="_xclick"> <!-- if paypal buy now -->
    <input type="hidden" name="cmd" value="_xclick-subscriptions"> <!-- if paypal subscription -->
    <input type="hidden" name="add" value="1">
    <input type="hidden" name="business" value="seller_1350878263_biz@gmail.com"> <!-- seller email --> 
    <input type="hidden" name="custom" value="package"/> <!-- custom field -->
    <input type="hidden" name="item_name" value='item name'> <!-- item name -->
    <input type="hidden" name="item_number" value='32'> <!-- item number -->
    <input type="hidden" name="amount" value="30.00"> <!-- price -->
    <input type="hidden" name="shipping" value="0.00"> <!-- shipping price  -->
    <input type="hidden" name="handling" value="0.00"> <!-- handling price  -->
    <input type="hidden" name="currency_code" value="USD"> <!-- currency -->
    <input type="hidden" name="notify_url" value="paypal_process.php"> <!-- database entry,co,putation after payment is done by this page -->
    <input name="return" value="payment_success.php" type="hidden"> <!-- user redirected to this page after payment -->
    <input name="cancel_return" value="cancel.php" type="hidden"> <!-- user redirected to this page if cancelled payment  -->
    <input type="hidden" name="undefined_quantity" value="1"> <!-- With Buy Now buttons, you can require buyers to specify the desired quantity of the item by using the undefined_quantity HTML variable: -->
    <input type="image" src="http://www.paypalobjects.com/en_US/i/btn/x-click-but22.gif" border="0" name="submit" width="87" height="23" alt="Make payments with PayPal - it's fast, free and secure!">
    </form> 

 2 . Download IPN Listener

Download the files from here and place it in your webdirectory, we need to include ipnlistener.php in one of our file. (Courtesy:  Micah Carrick)




3. paypal.class.php to validate the ipn and data

<?php
include('ipnlistener.php'); // ipnlisteneris the file which we downloaded in previous step
class paypal_auth
{
      private $listener;
      private $admin_mail;
      private $primarymail;
      function __construct()
      {
             $this->admin_mail="adminmail@domain.com"; // the email where you wish to receive the status report
             $this->primarymail="seller_1350878263_biz@gmail.com"; // ur paypal seller mail
             $this->listener = new IpnListener(); // creating an object of IpnListener
             $this->listener->use_sandbox = true; // 'true' if using sandbox, 'false' otherwise
      }

      /* function to validate ipn */
      function validate_ipn()
      {
             try
             {
                  $this->listener->requirePostMethod();
                  $verified = $this->listener->processIpn();
             } 
             catch (Exception $e)
             {
                error_log($e->getMessage());
                exit(0);
             }
             return $verified; // 'false'if not valid 'true' if valid 
      }
      function check_ipn($data)
      {
    
        if(!($this->validate_ipn()))
                {
                        return "invalid ipn";
                        exit;
                }
                $errmsg = '';   // stores errors from fraud checks
        
        // 1. Make sure the payment status is "Completed" 
        if ($data['payment_status'] != 'Completed')
                { 
            // simply ignore any IPN that is not completed
            exit(0); 
        }
        
        // 2. Make sure seller email matches your primary account email.
        if ($data['receiver_email'] != $this->primarymail)
                {
            $errmsg .= "'receiver_email' does not match: ";
            $errmsg .= $data['receiver_email']."\n";
        }
        
        // 3. Make sure the amount(s) paid match
        if(!(check_price($data['item_number'],$data['mc_gross'],$data['quantity']))) //check_price()is a function to check the price of the commodity from database) 
                {
            $errmsg .= "'mc_gross' does not match: ";
            $errmsg .= $data['mc_gross']."\n";
        }
        
        // 4. Make sure the currency code matches
        if ($data['mc_currency'] != 'USD') {
            $errmsg .= "'mc_currency' does not match: ";
            $errmsg .= $data['mc_currency']."\n";
        }
                else
                { 
                        $errmsg=$errmsg."noerror";
                }
                $status=array();
                $status['error']=$errmsg;
                $status['report']=$this->listener->getTextReport();
                $status['txn_id']=$data['txn_id'];
                return $status;
        // TODO: Check for duplicate txn_id
        
        
        } 
      
}

4. Finally paypal_process.php to do all the computation when payment is made.

<?php
session_start();
include('paypal.class.php');// checks for fraud in ipn
$paypal=new paypal_auth();//object of paypal.class


//IF PAYPAL CART
//-----------------------------------------------------------------------
if($_POST['txn_type']=="cart")
{
   
        for($i=1;$i<($_POST['num_cart_items']+1);$i++) // cart there would be more than one items so loop through
    {
        /* paypal informations */
        $data=$_POST;  // We store all the post variables in an arraynamed $data
        $status=$paypal->check_ipn($data); // checking ipn
        if($status['error']!="noerror") // in case of fraud ipn not validated
        {
           
            $errorstatus['error']=$status['error'];
            $errorstatus['report']=$status['report'];
            $errorstatus['ip']=$_SERVER['REMOTE_ADDR']; 
            mail("youremail@domain.com", 'IPN Fraud Warning', $status['error']); 
            mail("youremail@domain.com", 'IPN Fraud Warning', $status['report']); 
        }
        else
        {
            // things to be done after successful payment   
        }
    }
} 


//IF PAYPAL SUBSCRIBE
//----------------------------------------------------------------------------
else if($_POST['txn_type']=='subscr_payment')
{
        $data=$_POST;  // We store all the post variables in an arraynamed $data
    $status=$paypal->check_ipn($data); //checking IPN
    if($status['error']!="noerror") // in case of fraud ipn not validated
    {
        $errorstatus['error']=$status['error'];
            $errorstatus['report']=$status['report'];
            $errorstatus['ip']=$_SERVER['REMOTE_ADDR']; 
            mail("youremail@domain.com", 'IPN Fraud Warning', $status['error']); 
        mail("youremail@domain.com", 'IPN Fraud Warning', $status['report']); 
    }
    else
    {
        // things to be done after successful payment       
    }
         
          
}

//IF PAYPAL BUY NOW
//------------------------------------------------------------------------------------
else if($_POST['txn_type']=='express_checkout')
{
  
    $data=$_POST;  // We store all the post variables in an arraynamed $data
    $status=$paypal->check_ipn($data); //checking IPN,all the pos
    if($status['error']!="noerror") // in case of fraud ipn not validated
    {
        $errorstatus['error']=$status['error'];
            $errorstatus['report']=$status['report'];
            $errorstatus['ip']=$_SERVER['REMOTE_ADDR']; 
            mail("youremail@domain.com", 'IPN Fraud Warning', $status['error']); 
        mail("youremail@domain.com", 'IPN Fraud Warning', $status['report']); 
    }
    else
    {
        // things to be done after successful payment       
    }
   
}

?>

Paypal list of postitems

payment_status                 -              'completed when payment complete'
first_name                     -              'firstname of the buyer'
last_name                      -              'lastname of the buyer'
payer_email                    -              'email of the buyer'
receiver_email                 -              'seller email'
item_number                    -              'item number'
mc_gross                       -              'total price payed'
mc_currency                    -              'currency'
custom                         -              'custom field value'
ipn_track_id                   -              'unique track id'
receiver_id                    -              'receiver id'
txn_id                         -              'unique transaction id usually stored by the buyer in db'
subscr_id                      -              'unique subscriber id in case of subscription (stored in db)' 
verify_sign                    -              'unique id'
payer_id                       -              'id of the payer'
quantity                       -              'no of items bought'