simple paypal ipn

Hi
I'm trying to code a simple paypal IPN. I'll need your help. thanks in advance
please check the process below and add your comments and help about the missing parts.
firstpage:

<form action="order.php" method="post">
What do you want to buy?<input type="text" name="product" ><br>
How many? <input type="text" name="num" ><br>
Your paypal id: <input type="text" name="email" ><br>
<input type="submit" name="sendorder">
</form>

HTML:

order.php:
//collect data from db to get the price and calculate the price
and show a confirmation page with readonly fields to send to paypal: ( with the correct values

<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
price <input type="text" name="num" readonly="readonly" value="<?php echo $price; ?>"><br>
Your paypal id: <input type="text" name="email" value="<?php echo $email; ?>" readonly="readonly"><br>
<input type="submit" name="confirmorder">
</form>

HTML:

Ok
I have sent the info to paypal. then what happens?

 

Hi there,

specify the following hidden elements in your form :

<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="notify_url" value=" processing url ">
<input type="hidden" name="return" value="return url">
<input type="hidden" name="business" value=" your email with paypal ">

Specify your values , for notify_url set your url which contains your ipn processing. That is this script will process the stuff based on the response by the paypal can be verified or Invalid.

Get your sample script from here :

paypaltech.com/content/index.php?option=com_content&task=view&id=25&Itemid=49

 

thanks
the url you gave me suggests me a code:

<?php




/////////////////////////////////////////////////
/////////////Begin Script below./////////////////
/////////////////////////////////////////////////

// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-validate';
foreach ($_POST as $key => $value) {
$value = urlencode(stripslashes($value));
$req .= "&$key=$value";
}
// 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 ('www.paypal.com', 80, $errno, $errstr, 30);


// assign posted variables to local variables
$item_name = $_POST['item_name'];
$business = $_POST['business'];
$item_number = $_POST['item_number'];
$payment_status = $_POST['payment_status'];
$mc_gross = $_POST['mc_gross'];
$payment_currency = $_POST['mc_currency'];
$txn_id = $_POST['txn_id'];
$receiver_email = $_POST['receiver_email'];
$receiver_id = $_POST['receiver_id'];
$quantity = $_POST['quantity'];
$num_cart_items = $_POST['num_cart_items'];
$payment_date = $_POST['payment_date'];
$first_name = $_POST['first_name'];
$last_name = $_POST['last_name'];
$payment_type = $_POST['payment_type'];
$payment_status = $_POST['payment_status'];
$payment_gross = $_POST['payment_gross'];
$payment_fee = $_POST['payment_fee'];
$settle_amount = $_POST['settle_amount'];
$memo = $_POST['memo'];
$payer_email = $_POST['payer_email'];
$txn_type = $_POST['txn_type'];
$payer_status = $_POST['payer_status'];
$address_street = $_POST['address_street'];
$address_city = $_POST['address_city'];
$address_state = $_POST['address_state'];
$address_zip = $_POST['address_zip'];
$address_country = $_POST['address_country'];
$address_status = $_POST['address_status'];
$item_number = $_POST['item_number'];
$tax = $_POST['tax'];
$option_name1 = $_POST['option_name1'];
$option_selection1 = $_POST['option_selection1'];
$option_name2 = $_POST['option_name2'];
$option_selection2 = $_POST['option_selection2'];
$for_auction = $_POST['for_auction'];
$invoice = $_POST['invoice'];
$custom = $_POST['custom'];
$notify_version = $_POST['notify_version'];
$verify_sign = $_POST['verify_sign'];
$payer_business_name = $_POST['payer_business_name'];
$payer_id =$_POST['payer_id'];
$mc_currency = $_POST['mc_currency'];
$mc_fee = $_POST['mc_fee'];
$exchange_rate = $_POST['exchange_rate'];
$settle_currency  = $_POST['settle_currency'];
$parent_txn_id  = $_POST['parent_txn_id'];

// subscription specific vars

$subscr_id = $_POST['subscr_id'];
$subscr_date = $_POST['subscr_date'];
$subscr_effective  = $_POST['subscr_effective'];
$period1 = $_POST['period1'];
$period2 = $_POST['period2'];
$period3 = $_POST['period3'];
$amount1 = $_POST['amount1'];
$amount2 = $_POST['amount2'];
$amount3 = $_POST['amount3'];
$mc_amount1 = $_POST['mc_amount1'];
$mc_amount2 = $_POST['mc_amount2'];
$mc_amount3 = $_POST['mcamount3'];
$recurring = $_POST['recurring'];
$reattempt = $_POST['reattempt'];
$retry_at = $_POST['retry_at'];
$recur_times = $_POST['recur_times'];
$username = $_POST['username'];
$password = $_POST['password'];

//auction specific vars

$for_auction = $_POST['for_auction'];
$auction_closing_date  = $_POST['auction_closing_date'];
$auction_multi_item  = $_POST['auction_multi_item'];
$auction_buyer_id  = $_POST['auction_buyer_id'];



//DB connect creds and email 
$notify_email =  "my@nitification";         //email address to which debug emails are sent to
$DB_Server = "severname"; //your MySQL Server
$DB_Username = "dbusername"; //your MySQL User Name
$DB_Password = "dbpass"; //your MySQL Password
$DB_DBName = "db"; //your MySQL Database Name


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



//create MySQL connection
$Connect = @mysql_connect($DB_Server, $DB_Username, $DB_Password)
or die("Couldn't connect to MySQL:<br>" . mysql_error() . "<br>" . mysql_errno());


//select database
$Db = @mysql_select_db($DB_DBName, $Connect)
or die("Couldn't select database:<br>" . mysql_error(). "<br>" . mysql_errno());


$fecha = date("m")."/".date("d")."/".date("Y");
$fecha = date("Y").date("m").date("d");

//check if transaction ID has been processed before
$checkquery = "select txnid from paypal_payment_info where txnid='".$txn_id."'";
$sihay = mysql_query($checkquery) or die("Duplicate txn id check query failed:<br>" . mysql_error() . "<br>" . mysql_errno());
$nm = mysql_num_rows($sihay);
if ($nm == 0){

//execute query



    if ($txn_type == "cart"){
    $strQuery = "insert into paypal_payment_info(paymentstatus,buyer_email,firstname,lastname,street,city,state,zipcode,country,mc_gross,mc_fee,memo,paymenttype,paymentdate,txnid,pendingreason,reasoncode,tax,datecreation) values ('".$payment_status."','".$payer_email."','".$first_name."','".$last_name."','".$address_street."','".$address_city."','".$address_state."','".$address_zip."','".$address_country."','".$mc_gross."','".$mc_fee."','".$memo."','".$payment_type."','".$payment_date."','".$txn_id."','".$pending_reason."','".$reason_code."','".$tax."','".$fecha."')";

     $result = mysql_query($strQuery) or die("Cart - paypal_payment_info, Query failed:<br>" . mysql_error() . "<br>" . mysql_errno());
     for ($i = 1; $i <= $num_cart_items; $i++) {
         $itemname = "item_name".$i;
         $itemnumber = "item_number".$i;
         $on0 = "option_name1_".$i;
         $os0 = "option_selection1_".$i;
         $on1 = "option_name2_".$i;
         $os1 = "option_selection2_".$i;
         $quantity = "quantity".$i;

         $struery = "insert into paypal_cart_info(txnid,itemnumber,itemname,os0,on0,os1,on1,quantity,invoice,custom) values ('".$txn_id."','".$_POST[$itemnumber]."','".$_POST[$itemname]."','".$_POST[$on0]."','".$_POST[$os0]."','".$_POST[$on1]."','".$_POST[$os1]."','".$_POST[$quantity]."','".$invoice."','".$custom."')";
         $result = mysql_query($struery) or die("Cart - paypal_cart_info, Query failed:<br>" . mysql_error() . "<br>" . mysql_errno());

     }
    }



    else{
     $strQuery = "insert into paypal_payment_info(paymentstatus,buyer_email,firstname,lastname,street,city,state,zipcode,country,mc_gross,mc_fee,itemnumber,itemname,os0,on0,os1,on1,quantity,memo,paymenttype,paymentdate,txnid,pendingreason,reasoncode,tax,datecreation) values ('".$payment_status."','".$payer_email."','".$first_name."','".$last_name."','".$address_street."','".$address_city."','".$address_state."','".$address_zip."','".$address_country."','".$mc_gross."','".$mc_fee."','".$item_number."','".$item_name."','".$option_name1."','".$option_selection1."','".$option_name2."','".$option_selection2."','".$quantity."','".$memo."','".$payment_type."','".$payment_date."','".$txn_id."','".$pending_reason."','".$reason_code."','".$tax."','".$fecha."')";
     $result = mysql_query("insert into paypal_payment_info(paymentstatus,buyer_email,firstname,lastname,street,city,state,zipcode,country,mc_gross,mc_fee,itemnumber,itemname,os0,on0,os1,on1,quantity,memo,paymenttype,paymentdate,txnid,pendingreason,reasoncode,tax,datecreation) values ('".$payment_status."','".$payer_email."','".$first_name."','".$last_name."','".$address_street."','".$address_city."','".$address_state."','".$address_zip."','".$address_country."','".$mc_gross."','".$mc_fee."','".$item_number."','".$item_name."','".$option_name1."','".$option_selection1."','".$option_name2."','".$option_selection2."','".$quantity."','".$memo."','".$payment_type."','".$payment_date."','".$txn_id."','".$pending_reason."','".$reason_code."','".$tax."','".$fecha."')") or die("Default - paypal_payment_info, Query failed:<br>" . mysql_error() . "<br>" . mysql_errno());
    }


    // send an email in any case
 echo "Verified";
     mail($notify_email, "VERIFIED IPN", "$res\n $req\n $strQuery\n $struery\n  $strQuery2");
}
else {
// send an email
mail($notify_email, "VERIFIED DUPLICATED TRANSACTION", "$res\n $req \n $strQuery\n $struery\n  $strQuery2");
}

    //subscription handling branch
    if ( $txn_type == "subscr_signup"  ||  $txn_type == "subscr_payment"  ) {

      // insert subscriber payment info into paypal_payment_info table
      $strQuery = "insert into paypal_payment_info(paymentstatus,buyer_email,firstname,lastname,street,city,state,zipcode,country,mc_gross,mc_fee,memo,paymenttype,paymentdate,txnid,pendingreason,reasoncode,tax,datecreation) values ('".$payment_status."','".$payer_email."','".$first_name."','".$last_name."','".$address_street."','".$address_city."','".$address_state."','".$address_zip."','".$address_country."','".$mc_gross."','".$mc_fee."','".$memo."','".$payment_type."','".$payment_date."','".$txn_id."','".$pending_reason."','".$reason_code."','".$tax."','".$fecha."')";
      $result = mysql_query($strQuery) or die("Subscription - paypal_payment_info, Query failed:<br>" . mysql_error() . "<br>" . mysql_errno());


         // insert subscriber info into paypal_subscription_info table
        $strQuery2 = "insert into paypal_subscription_info(subscr_id , sub_event, subscr_date ,subscr_effective,period1,period2, period3, amount1 ,amount2 ,amount3,  mc_amount1,  mc_amount2,  mc_amount3, recurring, reattempt,retry_at, recur_times, username ,password, payment_txn_id, subscriber_emailaddress, datecreation) values ('".$subscr_id."', '".$txn_type."','".$subscr_date."','".$subscr_effective."','".$period1."','".$period2."','".$period3."','".$amount1."','".$amount2."','".$amount3."','".$mc_amount1."','".$$mc_amount2."','".$$mc_amount3."','".$recurring."','".$reattempt."','".$retry_at."','".$recur_times."','".$username."','".$password."', '".$txn_id."','".$payer_email."','".$fecha."')";
        $result = mysql_query($strQuery2) or die("Subscription - paypal_subscription_info, Query failed:<br>" . mysql_error() . "<br>" . mysql_errno());


             mail($notify_email, "VERIFIED IPN", "$res\n $req\n $strQuery\n $struery\n  $strQuery2");

    }
}

// if the IPN POST was 'INVALID'...do this


else if (strcmp ($res, "INVALID") == 0) {
// log for manual investigation

mail($notify_email, "INVALID IPN", "$res\n $req");
}
}
fclose ($fp);
}
?>

PHP:

should my processing url be the address of that code?
then what happens when paypal responds back? how can i verify the payment that has been done is what was to be? is that code doing it automatically?