Friday, December 24, 2010

PHP Paypal IPN Integration Class v1.0.0

<?php
/*******************************************************************************
*                      PHP Paypal IPN Integration Class
*******************************************************************************
*      Author:     Micah Carrick
*      Email:      email@micahcarrick.com
*      Website:    http://www.micahcarrick.com
*
*      File:       paypal.class.php
*      Version:    1.0.0
*      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.
*     
*******************************************************************************
*  VERION HISTORY:

*      v1.0.0 [04.16.2005] - Initial Version
*
*******************************************************************************
*  DESCRIPTION:
*
*      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', 'somebody@domain.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_log.txt';
     
$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
     
$this->add_field('cmd','_xclick');
     
   }
   
   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() {

     
// this function actually generates an entire HTML page consisting of
      // a form with hidden elements which is submitted to paypal via the
      // BODY element's onLoad attribute.  We do this so that you can validate
      // any POST vars from you custom form before submitting to paypal.  So
      // basically, you'll have your own form which is submitted to your script
      // to validate the data, which in turn calls this function to create
      // another hidden form and submit to paypal.

      // The user will briefly see a message on the screen that reads:
      // "Please wait, your order is being processed..." and then immediately
      // is redirected to paypal.

     
echo "<html>\n";
      echo
"<head><title>Processing Payment...</title></head>\n";
      echo
"<body onLoad=\"document.form.submit();\">\n";
      echo
"<center><h3>Please wait, your order is being processed...</h3></center>\n";
      echo
"<form method=\"post\" name=\"form\" action=\"".$this->paypal_url."\">\n";

      foreach (
$this->fields as $name => $value) {
         echo
"<input type=\"hidden\" name=\"$name\" value=\"$value\">";
      }

      echo
"</form>\n";
      echo
"</body></html>\n";
   
   }
   
   function
validate_ipn() {

     
// parse the paypal URL
     
$url_parsed=parse_url($this->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 .= $field.'='.urlencode($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";
         
$this->log_ipn_results(false);       
         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.
         
$this->log_ipn_results(true);
         return
true;       
         
      } else {
 
         
// Invalid IPN transaction.  Check the log for details.
         
$this->last_error = 'IPN Validation Failed.';
         
$this->log_ipn_results(false);   
         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";
      else
$text .= 'FAIL: '.$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
     
$fp=fopen($this->ipn_log_file,'a');
     
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\">
            <tr>
               <td bgcolor=\"black\"><b><font color=\"white\">Field Name</font></b></td>
               <td bgcolor=\"black\"><b><font color=\"white\">Value</font></b></td>
            </tr>"
;
     
     
ksort($this->fields);
      foreach (
$this->fields as $key => $value) {
         echo
"<tr><td>$key</td><td>".urldecode($value)." </td></tr>";
      }

      echo
"</table><br>";
   }
}         
?>

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