PayPal IPN - Testing - Does Not Work in Sandbox

Question

I am trying to code a simple PayPal purchase page with options on my site. However, I am having trouble testing it. For some odd reason, when I use " http://paypal.com/cgi-bin/webscr " as the form URL, it seems to work, however I can't test the IPN without someone purchasing it. If I leave it as " http://sandbox.paypal.com/cgi-bin/webscr ", it will pop up with this on the PayPal Sandbox site,

PayPal cannot process this transaction because of a problem with the seller's website. Please contact the seller directly to resolve this problem.

Below is my Form:

<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post" target="_top">
    <input type="hidden" name="cmd" value="_s-xclick">
    <input type="hidden" name="hosted_button_id" value="YDPZBQ2LRBCSE">
    <table>
    <tr><td><input type="hidden" name="on0" value="Packages">Packages</td></tr><tr><td><select name="os0">
    <option value="Bronze">Bronze $10.00 USD</option>
    <option value="Silver">Silver $25.00 USD</option>
    <option value="Gold">Gold $50.00 USD</option>
    </select> </td></tr>
    <tr><td><input type="hidden" name="on1" value="Wubbo Username">Wubbo Username</td></tr><tr><td><input type="text" name="os1" maxlength="200"></td></tr>
    </table>
    <input type="hidden" name="currency_code" value="USD">
    <input type="image" src="http://wubbo.me/paypal/buynow.png" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
    <img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>

And here is my IPN Code:

<?php
mysql_connect("localhost", "root", "PASSWORD") or die(mysql_error());
mysql_select_db("DATABASE") or die(mysql_error());

// STEP 1: read POST data
// Reading POSTed data directly from $_POST causes serialization issues with array data in the POST.
// Instead, read raw POST data from the input stream. 
$raw_post_data = file_get_contents('php://input');
$raw_post_array = explode('&', $raw_post_data);
$myPost = array();
foreach ($raw_post_array as $keyval) {
    $keyval = explode ('=', $keyval);
if (count($keyval) == 2)
 $myPost[$keyval[0]] = urldecode($keyval[1]);
}
// read the IPN message sent from PayPal and prepend 'cmd=_notify-validate'
$req = 'cmd=_notify-validate';
if(function_exists('get_magic_quotes_gpc')) {
    $get_magic_quotes_exists = true;
} 
foreach ($myPost as $key => $value) {        
    if($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) { 
        $value = urlencode(stripslashes($value)); 
    } else {
        $value = urlencode($value);
    }
    $req .= "&$key=$value";
}

// Step 2: POST IPN data back to PayPal to validate
$ch = curl_init('https://www.sandbox.paypal.com/cgi-bin/webscr');
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
// In wamp-like environments that do not come bundled with root authority certificates,
// please download 'cacert.pem' from "http://curl.haxx.se/docs/caextract.html" and set 
// the directory path of the certificate as shown below:
// curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/cacert.pem');
if( !($res = curl_exec($ch)) ) {
    // error_log("Got " . curl_error($ch) . " when processing IPN data");
curl_close($ch);
exit;
}
curl_close($ch);

// inspect IPN validation result and act accordingly
if (strcmp ($res, "VERIFIED") == 0) {
    // The IPN is verified, process it:
    // check whether the payment_status is Completed
    // check that txn_id has not been previously processed
    // check that receiver_email is your Primary PayPal email
    // check that payment_amount/payment_currency are correct
    // process the notification
    // assign posted variables to local variables
    $package = $_POST['os0'];
    $username = $_POST['os1'];

    if ($package == 'Bronze') {
        mysql_query("UPDATE `users` SET `vip_points` = (`vip_points` + 10) WHERE username = '" . $username . "'");
    } else if ($package == 'Silver') {
        mysql_query("UPDATE `users` SET `vip_points` = (`vip_points` + 30) WHERE username = '" . $username . "'");
    } else if ($package == 'Gold') {
        mysql_query("UPDATE `users` SET `vip_points` = (`vip_points` + 100) WHERE username = '" . $username . "'");
    }
}


} else if (strcmp ($res, "INVALID") == 0) {
// IPN invalid, log for manual investigation
echo "The response from IPN was: <b>" .$res ."</b>";
}
?>

Any assistance would be greatly appreciated!

Answer 1

When you're using a hosted button you can't just change it from paypal.com to sandbox.paypal.com. You would have to create a separate hosted button from within your sandbox seller account.

Then you would use a sandbox buyer account to make purchases through that button, and if IPN is setup in the seller account it will trigger accordingly.