Question

So, this is a new one on me. My Paypal IPN has been working for sometime, and started getting an error today.

During the postback to verify with PayPal (adding cmd=_notify-validate), the PayPal responder says “no that wasn’t from me”. The only thing bizarre about this particular entry is (I believe) the way the user specified their address:

123 Address Street
#789

Everything else seems normal and the IPN-handler is handling other notifications quite happily.

Anyone seen anything like this?

Answer 1

Okay, so I’ve found my error, and yes, it is related to the newline in the address.

Basically I was doing this:

foreach ($post_array as $name => $value) {
  $value = urlencode($value);
  $post_string .= $name . '=' . $value . '&';
}
$post_string .= "cmd=_notify-validate";

When I needed to also convert the /n to a /r/n, like so:

foreach ($post_array as $name => $value) {
  $value = urlencode(str_replace("\n", "\r\n", $value));
  $post_string .= $name . '=' . $value . '&';
}
$post_string .= "cmd=_notify-validate";

Now PayPal is happy.

Le sigh.