Question : PayPal IPN Stuff

Okay, here's the thing.  I'm really not that good at perl programming, so if I can get a little help here I would really appreciate it.  PayPal lets you set up a script on your site that processes information and sends nonsense back to their site.  I get the basics of perl programming.  I can store things in a database and print dynamic html files, but that's as far as I go.  So I need some help in getting this script to work.  I want to, obviously, process the stuff, but also send an email to the user with a custom message.  This is the sample code they give:

#!/usr/local/bin/perl

# read post from PayPal system and add 'cmd'
read (STDIN, $query, $ENV{'CONTENT_LENGTH'});
$query .= '&cmd=_notify-validate';

# post back to PayPal system to validate
use LWP::UserAgent;
$ua = new LWP::UserAgent;
$req = new HTTP::Request 'POST','https://www.paypal.com/cgi-bin/webscr';
$req->content_type('application/x-www-form-urlencoded');
$req->content($query);
$res = $ua->request($req);

# split posted variables into pairs
@pairs = split(/&/, $query);
$count = 0;
foreach $pair (@pairs) {
($name, $value) = split(/=/, $pair);
$value =~ tr/+/ /;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
$variable{$name} = $value;
$count++;
}

# assign posted variables to local variables
# note: additional IPN variables also available -- see IPN documentation
$item_name = $variable{'item_name'};
$receiver_email = $variable{'receiver_email'};
$item_number = $variable{'item_number'};
$invoice = $variable{'invoice'};
$payment_status = $variable{'payment_status'};
$payment_gross = $variable{'payment_gross'};
$txn_id = $variable{'txn_id'};
$payer_email = $variable{'payer_email'};

if ($res->is_error) {
# HTTP error
}
elsif ($res->content eq 'VERIFIED') {
# check the payment_status=Completed
# check that txn_id has not been previously processed
# check that receiver_email is an email address in your PayPal account
# process payment
}
elsif ($res->content eq 'INVALID') {
# log for manual investigation
}
else {
# error
}
print "content-type: text/plain\n\nOK\n";


...And the rest of the details are in the IPN section of the PayPal web site.  Any any ANY help would be appreciated.

Thanks!
-Brian

Answer : PayPal IPN Stuff

Script is really straight forward with enough comments.

if ($res->is_error) {

#### When you come here that means, your script wasnt able to communicate with server. So write appropriate message like

print "Unable to communicate with Payment system.Please try again later.";


}
elsif ($res->content eq 'VERIFIED') {
# check the payment_status=Completed
# check that txn_id has not been previously processed
# check that receiver_email is an email address in your PayPal account
# process payment

## Payment is verified. Check variable named $payment_status.

if($payment_status eq 'Completed')
{
      show_success();
}

}
elsif ($res->content eq 'INVALID') {
# log for manual investigation
# print Something wrong related to payment.

print "Unable to process your request. Make sure your payment information is correct.";

}
else {
# error
print "Unable to process your payment. Try again later.";
}

sub show_success
{
   #Display appropriate message.
   #include code which can send mail.


}
print "content-type: text/plain\n\nOK\n";


That is it !!!
JD