Location: PHPKode > scripts > Event Registration > event-registration/paypal.class.php
 *                      PHP Paypal IPN Integration Class
 *      Author:     Micah Carrick
 *      Email:      hide@address.com
 *      Website:    http://www.micahcarrick.com
 *      File:       paypal.class.php
 *      Version:    1.3.0
 *      Copyright:  (c) 2005 - Micah Carrick 
 *                  You are free to use, distribute, and modify this software 
 *                  under the terms of the GNU General Public License.  See the
 *                  included license.txt file.
 *      v1.3.0 [10.10.2005] - Fixed it so that single quotes are handled the 
 *                            right way rather than simple stripping them.  This
 *                            was needed because the user could still put in
 *                            quotes.
 *      v1.2.1 [06.05.2005] - Fixed typo from previous fix :)
 *      v1.2.0 [05.31.2005] - Added the optional ability to remove all quotes
 *                            from the paypal posts.  The IPN will come back
 *                            invalid sometimes when quotes are used in certian
 *                            fields.
 *      v1.1.0 [05.15.2005] - Revised the form output in the submit_paypal_post
 *                            method to allow non-javascript capable browsers
 *                            to provide a means of manual form submission.
 *      v1.0.0 [04.16.2005] - Initial Version
 *      NOTE: See www.micahcarrick.com for the most recent version of this class
 *            along with any applicable sample files and other documentaion.
 *      This file provides a neat and simple method to interface with paypal and
 *      The paypal Instant Payment Notification (IPN) interface.  This file is
 *      NOT intended to make the paypal integration "plug 'n' play". It still
 *      requires the developer (that should be you) to understand the paypal
 *      process and know the variables you want/need to pass to paypal to
 *      achieve what you want.  
 *      This class handles the submission of an order to paypal aswell as the
 *      processing an Instant Payment Notification.
 *      This code is based on that of the php-toolkit from paypal.  I've taken
 *      the basic principals and put it in to a class so that it is a little
 *      easier--at least for me--to use.  The php-toolkit can be downloaded from
 *      http://sourceforge.net/projects/paypal.
 *      To submit an order to paypal, have your order form POST to a file with:
 *          $p = new paypal_class;
 *          $p->add_field('business', 'hide@address.com');
 *          $p->add_field('first_name', $_POST['first_name']);
 *          ... (add all your fields in the same manor)
 *          $p->submit_paypal_post();
 *      To process an IPN, have your IPN processing file contain:
 *          $p = new paypal_class;
 *          if ($p->validate_ipn()) {
 *          ... (IPN is verified.  Details are in the ipn_data() array)
 *          }
 *      In case you are new to paypal, here is some information to help you:
 *      1. Download and read the Merchant User Manual and Integration Guide from
 *         http://www.paypal.com/en_US/pdf/integration_guide.pdf.  This gives 
 *         you all the information you need including the fields you can pass to
 *         paypal (using add_field() with this class) aswell as all the fields
 *         that are returned in an IPN post (stored in the ipn_data() array in
 *         this class).  It also diagrams the entire transaction process.
 *      2. Create a "sandbox" account for a buyer and a seller.  This is just
 *         a test account(s) that allow you to test your site from both the 
 *         seller and buyer perspective.  The instructions for this is available
 *         at https://developer.paypal.com/ as well as a great forum where you
 *         can ask all your paypal integration questions.  Make sure you follow
 *         all the directions in setting up a sandbox test environment, including
 *         the addition of fake bank accounts and credit cards.

class paypal_class {
   var $last_error;                 // holds the last error encountered
   var $ipn_log;                    // bool: log IPN results to text file?
   var $ipn_log_file;               // filename of the IPN log
   var $ipn_response;               // holds the IPN response from paypal   
   var $ipn_data = array();         // array contains the POST values for IPN
   var $fields = array();           // array holds the fields to submit to paypal

   function paypal_class() {
      // initialization constructor.  Called when class is created.
      $this->paypal_url = 'https://www.paypal.com/cgi-bin/webscr';
      $this->last_error = '';
      $this->ipn_log_file = '.ipn_results.log';
      $this->ipn_log = true; 
      $this->ipn_response = '';
      // populate $fields array with a few default values.  See the paypal
      // documentation for a list of fields and their data types. These defaul
      // values can be overwritten by the calling script.

      $this->add_field('rm','2');          // Return method = POST
      //added to make special (like accented) characters works with Paypal 
      $this->add_field('charset', 'utf-8'); 
   function add_field($field, $value) {
      // adds a key=>value pair to the fields array, which is what will be 
      // sent to paypal as POST variables.  If the value is already in the 
      // array, it will be overwritten.
      $this->fields["$field"] = $value;

   function submit_paypal_post($pay_text) {

<form method="post" name="paypal_form" action="<?php echo $this->paypal_url?>">
  <?php foreach ($this->fields as $name => $value) {
         echo "<input type=\"hidden\" name=\"$name\" value=\"$value\"/>\n";
  <input type="submit" id="registration_payment_button" value="<?php echo $pay_text; /*changed by david fleming to make customizable*/ ?>">  
<?php  }
   function validate_ipn() {

      // parse the paypal URL

      // generate the post string from the _POST vars aswell as load the
      // _POST vars into an arry so we can play with them from the calling
      // script.
      $post_string = '';    
      foreach ($_POST as $field=>$value) { 
         $this->ipn_data["$field"] = $value;
         $post_string .= $field.'='.urlencode(stripslashes($value)).'&'; 
      $post_string.="cmd=_notify-validate"; // append ipn command

      // open the connection to paypal
      $fp = fsockopen($url_parsed[host],"80",$err_num,$err_str,30); 
      if(!$fp) {
         // could not open the connection.  If loggin is on, the error message
         // will be in the log.
         $this->last_error = "fsockopen error no. $errnum: $errstr";
         return false;
      } else { 
         // Post the data back to paypal
         fputs($fp, "POST $url_parsed[path] HTTP/1.1\r\n"); 
         fputs($fp, "Host: $url_parsed[host]\r\n"); 
         fputs($fp, "Content-type: application/x-www-form-urlencoded\r\n"); 
         fputs($fp, "Content-length: ".strlen($post_string)."\r\n"); 
         fputs($fp, "Connection: close\r\n\r\n"); 
         fputs($fp, $post_string . "\r\n\r\n"); 

         // loop through the response from the server and append to variable
         while(!feof($fp)) { 
            $this->ipn_response .= fgets($fp, 1024); 

         fclose($fp); // close connection

      if (eregi("VERIFIED",$this->ipn_response)) {
         // Valid IPN transaction.
         return true;       
      } else {
         // Invalid IPN transaction.  Check the log for details.
         $this->last_error = 'IPN Validation Failed.';
         return false;
   function log_ipn_results($success) {
      if (!$this->ipn_log){ return; } // is logging turned off?
      // Timestamp
      $text = '['.date('m/d/Y g:i A').'] - '; 
      // Success or failure being logged?
      if ($success) {
		  $text .= "SUCCESS!\n";
	  	$text .= 'FAIL: '.$this->last_error."\n";
      // Log the POST variables
      $text .= "IPN POST Vars from Paypal:\n";
      foreach ($this->ipn_data as $key=>$value) {
         $text .= "$key=$value, ";
      // Log the response from the paypal server
      $text .= "\nIPN Response from Paypal Server:\n ".$this->ipn_response;
      // Write to log
      fwrite($fp, $text . "\n\n"); 

      fclose($fp);  // close file

   function dump_fields() {
      // Used for debugging, this function will output all the field/value pairs
      // that are currently defined in the instance of the class using the
      // add_field() function.
      echo "
<h3>paypal_class->dump_fields() Output:</h3>
      echo "
<table width=\"95%\" border=\"1\" cellpadding=\"2\" cellspacing=\"0\">
    <td bgcolor=\"black\"><b><font color=\"white\">Field Name</font></b></td>
    <td bgcolor=\"black\"><b><font color=\"white\">Value</font></b></td>
  foreach ($this->fields as $key => $value) {
  echo "
  echo "
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