App Engine (PHP) returns error code 204 on PayPal IPN

[Joonas Alhonen via StackOverflow]

I'm trying to create PayPal IPN listener using code provided in https://developer.paypal.com/docs/classic/ipn/ht_ipn/ . Everything works ok when testing with Chrome (GET), but when PayPal tries to contact the script (POST), HTTP 500 is returned and App Engine log says error_code=204.

I have tried with and without the certificate.

Code is copy-pasted from PayPal website.

I'm using php55 runtime and curl succesfully in other parts of the project.

<?php
try
{
    //require_once("sql.php");

    // 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

    $ch = curl_init('https://www.paypal.com/cgi-bin/webscr');
    curl_setopt($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($ch, CURLOPT_CAINFO, 'cacert.pem');
    if( !($res = curl_exec($ch)) ) {
        syslog(LOG_ERR, "Got " . curl_error($ch) . " when processing IPN data");
        curl_close($ch);
        exit;
    }
    curl_close($ch);


    // STEP 3: Inspect IPN validation result and act accordingly

    if (strcmp ($res, "VERIFIED") == 0) {
        $item = -1;

        if(isset($_POST["item_number"]))
        {
            $item = $_POST["item_number"];
        }
        else
        {
            syslog(LOG_ERR, "item_number not given");
        }

        if($_POST["payment_status"] == "Completed")
        {
            //$insert = $db->prepare("UPDATE purchases SET paid=1 WHERE id=?");
            //$insert->execute(array($item));
            syslog(LOG_INFO, "PAYMENT OK!, id: " . $item);
        }
        else
        {
            syslog(LOG_WARNING, "PAYMENT: " . $_POST["payment_status"]);
        }
    } else if (strcmp ($res, "INVALID") == 0) {
        // IPN invalid, log for manual investigation
        syslog(LOG_WARNING, "The response from IPN was: $res");
    }
}
catch(Exception $e)
{
    syslog(LOG_ERR, $e->getMessage());
}
?>

Please DO NOT REPLY directly to this email but go to StackOverflow:
http://stackoverflow.com/questions/29709902/app-engine-php-returns-error-code-204-on-paypal-ipn

[Pedro Lobito via StackOverflow]

I had the same problem, it was due to an invalid certificate:

Solution:

I followed the code comments on the paypal ipn listener sample and downloaded a new certificate from http://curl.haxx.se/docs/caextract.html (HTTPS from github: ca-bundle.crt) and replaced the old one. Problem solved.

Please DO NOT REPLY directly to this email but go to StackOverflow:

http://stackoverflow.com/questions/29709902/app-engine-php-returns-error-code-204-on-paypal-ipn/29710117#29710117