Paypal IPN继续重试然后失败

Question

我在IPN模拟器上测试过，看起来很好，正在发送和验证IPN。现在我正在测试沙盒，但在IPN历史记录中我可以看到传递状态不断重试然后失败。它永远不会被发送。 HTTP响应代码字段为空。我正在使用localhost，但我正在使用ngrok，我收到200 OK HTTP响应。我也想将数据插入到mysql数据库中，但我想这也是我不能的原因之一。我究竟做错了什么？我对PHP很新，我也遇到了类似的问题，但似乎没有找到解决方案。我整天都在这，这让我发疯。 :)非常感谢任何帮助或指南！

我正在使用github的脚本，这里是ipn.php：

<?php 
include 'xxxxxxx.php';
require('PaypalIPN.php');
use PaypalIPN;
$ipn = new PayPalIPN();
// Use the sandbox endpoint during testing.
$ipn->useSandbox();
$verified = $ipn->verifyIPN();
if ($verified) {
    $item_number = $_POST['item_number'];
    $txn_id = $_POST['txn_id'];
    $payment_gross = $_POST['mc_gross'];
    $currency_code = $_POST['mc_currency'];
    $payment_status = $_POST['payment_status'];

$insert =mysqli_query($conn, "INSERT INTO payments(item_number, txn_id,payment_gross,currency_code,payment_status) VALUES('".$item_number."','".$txn_id."','".$payment_gross."','".$currency_code."','".$payment_status."')");
}
?>

这是我的paypalIPN.php：

<?php
class PaypalIPN
{
    private $use_sandbox = false;
    private $use_local_certs = false;
    /*
     * PayPal IPN postback endpoints
     */
    const VERIFY_URI = 'https://ipnpb.paypal.com/cgi-bin/webscr';
    const SANDBOX_VERIFY_URI = 'https://ipnpb.sandbox.paypal.com/cgi-bin/webscr';
    /*
     * Possible responses from PayPal after the request is issued.
     */
    const VALID = 'VERIFIED';
    const INVALID = 'INVALID';
    /**
     * Sets the IPN verification to sandbox mode (for use when testing,
     * should not be enabled in production).
     * @return void
     */
    public function useSandbox()
    {
        $this->use_sandbox = true;
    }
    /**
     * Determine endpoint to post the verification data to.
     * @return string
     */
    public function getPaypalUri()
    {
        if ($this->use_sandbox) {
            return self::SANDBOX_VERIFY_URI;
        } else {
            return self::VERIFY_URI;
        }
    }
    /**
     * Verification Function
     * Sends the incoming post data back to paypal using the cURL library.
     *
     * @return bool
     * @throws Exception
     */
    public function verifyIPN()
    {
        if ( ! count($_POST)) {
            throw new Exception("Missing POST Data");
        }
        $raw_post_data = file_get_contents('php://input');
        $raw_post_array = explode('&', $raw_post_data);
        $myPost = [];
        foreach ($raw_post_array as $keyval) {
            $keyval = explode('=', $keyval);
            if (count($keyval) == 2) {
                // Since we do not want the plus in the datetime string to be encoded to a space, we manually encode it.
                if ($keyval[0] === 'payment_date') {
                    if (substr_count($keyval[1], '+') === 1) {
                        $keyval[1] = str_replace('+', '%2B', $keyval[1]);
                    }
                }
                $myPost[$keyval[0]] = urldecode($keyval[1]);
            }
        }
        // Build the body of the verification post request, adding the _notify-validate command.
        $req = 'cmd=_notify-validate';
        $get_magic_quotes_exists = false;
        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";
        }
        // Post the data back to paypal, using curl. Throw exceptions if errors occur.
        $ch = curl_init($this->getPaypalUri());
        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_SSLVERSION, 6);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        // This is often required if the server is missing a global cert bundle, or is using an outdated one.
        if ($this->use_local_certs) {
            curl_setopt($ch, CURLOPT_CAINFO, __DIR__ . "/cert/cacert.pem");
        }
        curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
        curl_setopt($ch, CURLOPT_HTTPHEADER, ['Connection: Close']);
        $res = curl_exec($ch);
        $info = curl_getinfo($ch);
        $http_code = $info['http_code'];
        if ($http_code != 200) {
            throw new Exception("PayPal responded with http code $http_code");
        }
        if ( ! ($res)) {
            $errno = curl_errno($ch);
            $errstr = curl_error($ch);
            curl_close($ch);
            throw new Exception("cURL error: [$errno] $errstr");
        }
        curl_close($ch);
        // Check if paypal verfifes the IPN data, and if so, return true.
        if ($res == self::VALID) {
            return true;
        } else {
            return false;
        }
    }
}

我还在我的html表单中插入了notify_url：

<input type='hidden' name='notify_url' value='http://xxxxxxx/xxxx/ipn.php'>