验证 IPN 时 IPN 响应为空白

Question

根据paypal document，当我们使用 IPN 将消息发送回 Paypal 后，我们会返回：-

PayPal will then send one single-word message, VERIFIED, if the message is valid; otherwise, it will send another single-word message, INVALID.

但是我时不时注意到即使付款成功，响应也可能是空白的。有没有其他人注意到这一点？

我要验证的代码是：-

var req = (HttpWebRequest)WebRequest.Create(Settings.PayPalPaymentUrl);

//Set values for the request back
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";
byte[] param = Request.BinaryRead(Request.ContentLength);
strRequest = Encoding.ASCII.GetString(param);
strRequest += "&cmd=_notify-validate";
req.ContentLength = strRequest.Length;

//Send the request to PayPal and get the response
var streamOut = new StreamWriter(req.GetRequestStream(), Encoding.ASCII);
streamOut.Write(strRequest);
streamOut.Close();
var streamIn = new StreamReader(req.GetResponse().GetResponseStream());
strResponse = streamIn.ReadToEnd();
streamIn.Close();

99% 的案例我收到了VERIFIED，但我们时不时地看到一条空消息。

Answer 1

如果有人直接访问该页面，而不是被 PayPal 击中，您会得到一个空白响应，这是怎么回事？