Paypal - Accept Credit Cards Online

PayPal - one of the pioneers of internet credit card processing without a merchant account. There are no set up fees, and the basic transaction costs are very low: $.30 plus 2.2 to 2.9%. It's a very easy way to facilitate payment and it has a wide international program. You can set up individual buttons to sell specific items from your web site. International merchants welcome and multiple currencies supported. Setup takes a few days as they verify your banking and credit card information. PayPal also allows for a "trial period" that delays the actual processing of the credit card - useful if you want to allow your customers to try your services for a 30-day free trial, for example.

Programming for Paypal Merchant Account Setup

Here are our example IPN PHP scripts using SSL.
To use the scripts below you need:

A server that supports fsockopen. (yahoo and a lot of other servers do not support fsockopen)
Write your own MySQL database handling functions.

IPN Notification Script
Let us see about one free php resource for developers wishing to integrate their projects into the PayPal Instant Payment Notification service, more genuinely known as IPN.

Just what you need to do is to set the database details found in $_Config array.
And need to update the functions given for each of the Payment_Status, like update your local database & mailings.

Config Variables
//--------------------------------------------------
// Update your Database Details here
//--------------------------------------------------

$_Config["DBHost"] = "localhost";
$_Config["DBUserName"] = "root";
$_Config["DBPassword"] = "";
$_Config["DBDatabaseName"] = "activemed";


Write Log File
This is where the log file will be created whenever the IPN script integrated at your backend. Note that this file must have write permission

//-----------------------------------------------------------
// Write the Log in ipn.log file. It should have write permission
//-----------------------------------------------------------
$myLogFile = fopen("ipn.log","a");
fwrite($log, "nnipn - " . gmstrftime ("%b %d %Y %H:%M:%S", time()) . "n");

Connect to DB
$myConnection = mysql_connect($_Config["DBHost"],$_Config["DBUserName"],$_Config["DBPassword"]) or die("Could not connect to the server") ;
$myDB = mysql_select_db($_Config["DBDatabaseName"],$myConnection) or die("database failed");

Standard PayPal Code
T he next step is to create a reply to validate the PayPal post. This bit of code first creates a new array ($postvars) containing all of the values posted from PayPal. Then it begins a reply message ($req), with 'cmd=_notify-validate'.
Using a 'for' loop, it adds a list of posted vars in the format 'variable=value .

//-----------------------------------------------------------
// Read post from PayPal system and create reply
// starting with: 'cmd=_notify-validate'...
// then repeating all values sent - VALIDATION.
//-----------------------------------------------------------

$postvars = array();
while (list ($key, $value) = each ($HTTP_POST_VARS)) {
$postvars[] = $key;
}
$req = 'cmd=_notify-validate';
for ($var = 0; $var < count ($postvars); $var++) {
$postvar_key = $postvars[$var];
$postvar_value = $$postvars[$var];
$req .= "&" . $postvar_key . "=" . urlencode ($postvar_value);
}


Then create an HTTP header for the reply message, open a connection...

//--------------------------------------------
// Create message to post back to PayPal...
// Open a socket to the PayPal server...
//--------------------------------------------
$header .= "POST /cgi-bin/webscr HTTP/1.0rn";
$header .= "Content-Type: application/x-www-form-urlencodedrn";
$header .= "Content-Length: " . strlen ($req) . "rnrn";
$fp = fsockopen ("www.paypal.com", 80, $errno, $errstr, 30);

Next to write the transaction details to the log file.
The log file is useful for debugging problems. You'll ideally never lose any details, and if the database is down for any reason, you need a backup..

//---------------------------------------------
fwrite($log, "Vals: ". $invoice." ". $receiver_email." ". $item_name." ". $item_ number." ". $quantity." ". $payment_status." ". $pending_reason." ".$payment_dat e." ". $payment_gross." ". $payment_fee." ". $txn_id." ". $txn_type." ". $first_ name." ". $last_name." ". $address_street." ". $address_city." ". $address_state . " ".$address_zip." ". $address_country." ". $address_status." ". $payer_email. " ". $payer_status." ". $payment_type." ". $notify_version." ". $verify_sign. " n");

Check Connection...
The variables $errstr and $errno are system variables which report details on the last error.

//----------------------------------------------------------------------
// Check HTTP connection made to PayPal OK, If not, print an error msg
//----------------------------------------------------------------------
if (!$fp) {
echo "$errstr ($errno)";
fwrite($log, "Failed to open HTTP connection!");
$res = "FAILED";
}

//--------------------------------------------------------
// If connected OK, write the posted values back, then...
//--------------------------------------------------------
else {
fputs ($fp, $header . $req);
//-------------------------------------------
// ...read the results of the verification...
// If VERIFIED = continue to process the TX...
//-------------------------------------------
while (!feof($fp)) {
$res = fgets ($fp, 1024);
if (strcmp ($res, "VERIFIED") == 0) {

If payment is complete, get the password from the database.
If the payment status is 'Completed'... The payment wasn't by e-check. The transaction's complete.

Using the 'while' construct to get the data into a local variable is just a convenience... We know that only 1 row will come back from the query.

//----------------------------------------------------------------------
// If the payment_status=Completed... Get the password for the product
// from the DB and email it to the customer. Do the completed Process in
// the function called completedProcess.
//----------------------------------------------------------------------
if (strcmp ($payment_status, "Completed") == 0) {
completedProcess();
}

Handle Incomplete Transactions
Inform the customer, and also inform yourself that something needs doing.

//----------------------------------------------------------------------
// If the payment_status is NOT Completed...
// Do the InComplete process in the function inCompleteProcess();
//----------------------------------------------------------------------
else {
inCompleteProcess();
}