错误502（错误网关）与HttpWebRequest的通过SSL发送请求时，

问题描述

我有下面的代码片断在传统的ASP，发送命令和检索通过SSL响应：

I have the following snippet in classic ASP, to send a command and retrieve the response over SSL:

Dim xmlHTTP
Set xmlHTTP = Server.CreateObject("Msxml2.ServerXMLHTTP.3.0")
xmlHTTP.open "POST", "https://www.example.com", False
xmlHTTP.setRequestHeader "Content-Type","application/x-www-form-urlencoded"
xmlHTTP.setRequestHeader "Content-Length", Len(postData)
xmlHTTP.Send postData
If xmlHTTP.status = 200 And Len(message) > 0 And Not Err Then
   Print xmlHTTP.responseText
End If

然后我使用作为参考来重新实现请求在C＃中：

Then I used this code as a reference to reimplement the request in c#:

private static string SendRequest(string url, string postdata)
{
   WebRequest rqst = HttpWebRequest.Create(url);
   // We have a proxy on the domain, so authentication is required.
   WebProxy proxy = new WebProxy("myproxy.mydomain.com", 8080);
   proxy.Credentials = new NetworkCredential("username", "password", "mydomain");
   rqst.Proxy = proxy;
   rqst.Method = "POST";
   if (!String.IsNullOrEmpty(postdata))
   {
       rqst.ContentType = "application/x-www-form-urlencoded";

       byte[] byteData = Encoding.UTF8.GetBytes(postdata);
       rqst.ContentLength = byteData.Length;
       using (Stream postStream = rqst.GetRequestStream())
       {
           postStream.Write(byteData, 0, byteData.Length);
           postStream.Close();
       }
   }
   ((HttpWebRequest)rqst).KeepAlive = false;
   StreamReader rsps = new StreamReader(rqst.GetResponse().GetResponseStream());
   string strRsps = rsps.ReadToEnd();
   return strRsps;
}

问题是，呼吁GetRequestStream当我不断收到引发WebException与消息远程服务器返回错误：（502）错误的网关

起初我还以为是不得不做与SSL证书验证。所以我说这行：

At first I thought it had to do with the SSL certificate verification. So I added this line:

ServicePointManager.CertificatePolicy = new AcceptAllCertificatePolicy();

其中，

Where

public class AcceptAllCertificatePolicy : ICertificatePolicy
{
    public bool CheckValidationResult(ServicePoint srvPoint,
                                      System.Security.Cryptography.X509Certificate certificate,
                                      WebRequest request,
                                      int certificateProblem)
    {
        return true;
    }
}

和我不断收到同样的502错误。任何想法？

And I keep getting the same 502 error. Any ideas?

推荐答案

的我得到这个问题的更详细的说明的帮助：代理返航的消息： 用户代理无法识别。所以，我手动设置。另外，我改为使用（）的代码，描述。最后的工作代码包含下面。

With the help of this I got a more detailed description of the problem: The proxy was returning the message: "The user agent is not recognized." So I set it manually. Also, I changed the code to use GlobalProxySelection.GetEmptyWebProxy(), as described here. The final working code is included below.

private static string SendRequest(string url, string postdata)
{
    if (String.IsNullOrEmpty(postdata))
        return null;
    HttpWebRequest rqst = (HttpWebRequest)HttpWebRequest.Create(url);
    // No proxy details are required in the code.
    rqst.Proxy = GlobalProxySelection.GetEmptyWebProxy();
    rqst.Method = "POST";
    rqst.ContentType = "application/x-www-form-urlencoded";
    // In order to solve the problem with the proxy not recognising the user
    // agent, a default value is provided here.
    rqst.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)";
    byte[] byteData = Encoding.UTF8.GetBytes(postdata);
    rqst.ContentLength = byteData.Length;

    using (Stream postStream = rqst.GetRequestStream())
    {
        postStream.Write(byteData, 0, byteData.Length);
        postStream.Close();
    }
    StreamReader rsps = new StreamReader(rqst.GetResponse().GetResponseStream());
    string strRsps = rsps.ReadToEnd();
    return strRsps;
}

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