HttpWebRequest无法访问http://xn--fanbys-exa.org/episodes.m4a.rss

Question

我有一个奇怪的问题访问以下网址:

http://xn--fanbys-exa.org/episodes.m4a.rss

这是代码:

    void WebRequestButton_Click( object sender, RoutedEventArgs e )
    {
        string url = "http://xn--fanbys-exa.org/episodes.m4a.rss"; 

        if ( Uri.IsWellFormedUriString( url, UriKind.Absolute ) )
        {
            HttpWebRequest webRequest = ( HttpWebRequest )HttpWebRequest.Create( url );
            if ( webRequest != null )
            {
                webRequest.BeginGetResponse( new AsyncCallback( ReadWebRequestCallback ), webRequest ); 
            }
        }
    }

    private void ReadWebRequestCallback( IAsyncResult callbackResult )
    {
        HttpWebRequest request = ( HttpWebRequest )callbackResult.AsyncState;
        HttpWebResponse response = null;

        try
        {
            response = ( HttpWebResponse )request.EndGetResponse( callbackResult );
        }
        catch ( Exception e )
        {
            System.Diagnostics.Debug.WriteLine( e );
        }

        if ( response != null )
        {
            using ( StreamReader httpwebStreamReader = new StreamReader( response.GetResponseStream( ) ) )
            {
                string results = httpwebStreamReader.ReadToEnd( );
                System.Diagnostics.Debug.WriteLine( results );
            }

            response.Close( );
        }
    }

使用request.EndGetResponse()读取响应会抛出此异常:

A first chance exception of type 'System.ArgumentException' occurred in System.Windows.dll
System.ArgumentException ---> System.ArgumentException: The parameter is incorrect.
   at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   at MS.Internal.XcpImports.WebRequest_Send(InternalWebRequest request)
   at MS.Internal.InternalWebRequest.Send()
   at System.Net.Browser.ClientHttpWebRequest.PrepareAndSendRequest(String method, Uri requestUri, Stream requestBodyStream, WebHeaderCollection headerCollection, CookieContainer cookieContainer)
   at System.Net.Browser.ClientHttpWebRequest.BeginGetResponseImplementation()
   at System.Net.Browser.ClientHttpWebRequest.InternalBeginGetResponse(AsyncCallback callback, Object state)
   at System.Net.Browser.ClientHttpWebRequest.BeginGetResponse(Async'UI Task' (Managed): Loaded 'System.Runtime.Serialization.dll'

据我所知,网址

http://xn--fanbys-exa.org/episodes.m4a.rss

很好.
我尝试的所有浏览器都可以处理它.

使用Fiddler进行测试表明没有从Windows Phone模拟器发送HTTP请求.

如果尝试了几个不同的URL(使用活动的Fiddler实例):

string url = "http://xn--fanbys-exa.org/episodes.m4a.rss"; 
    // not ok --> System.ArgumentException: The parameter is incorrect.

string url = "http://xn--fanbys-exa.org"; 
    // not ok --> System.ArgumentException: The parameter is incorrect.

string url = Uri.EscapeUriString( "http://xn--fanbys-exa.org/episodes.m4a.rss" ); 
    // not ok --> System.ArgumentException: The parameter is incorrect.

string url = "http://stackoverflow.com";        
    // ok, HTTP request is sent and response is received

string url = "http://stack--overflow.com";    
    // ok, HTTP request is sent and response is received 

string url = "http://xn--stackoverflow.com";    
    // ok, HTTP request is sent and response 502 is received
    // --> System.Net.WebException: The remote server returned an error: NotFound.

可以使用模拟器和设备重现该问题.
我的猜测是这可能与DNS有关.
我无法控制引用的网站及其DNS条目.

有任何想法吗 ？

Answer 1

是的，我也可以验证问题，并且在 fiddler 中也没有看到任何流量。有史以来最奇怪的错误！

  string url = "http://a--b-c.org"; - Fine
  string url = "http://xn--fanbys-exa.org"; - Error
  string url = "http://xn--2fanbys-exa.org"; - Error
  string url = "http://xn--fanbys2-exa.org"; - Error
  string url = "http://xn--fan2bys-exa.org"; - Error
  string url = "http://xn-fanbys-exa.org"; - Fine
  string url = "http://xn--b-exa.org"; - Fine
  string url = "http://xn--f.org"; - Fine
  string url = "http://a--fanbys-exa.org"; - Fine
  string url = "http://xn--fanbys-c.org"; - Fine
  string url = "http://xn--fanbys-exa2.org"; - Fine
  string url = "http://2xn--fanbys-exa.org"; - Fine
  string url = "http://xn--f-exa.org"; - Fine
  string url = "http://xn--fs-exa.org"; - Error
  string url = "http://x--fs-exa.org"; - Fine
  string url = "http://xn--fs.org"; - Fine
  string url = "http://xn--fs-.org"; - Fine
  string url = "http://xn--fs-e.org"; - Fine
  string url = "http://xn--fs-ea.org"; - Fine
  string url = "http://xn--fs-ex.org"; - Fine
  string url = "http://xn--fs-exx.org"; - Error
  string url = "http://xn--fs-eee.org"; - Error
  string url = "http://aa--aa-aaa.org"; - Fine
  string url = "http://aa--aa-eee.org"; - Fine
  string url = "http://xa--aa-eee.org"; - Fine
  string url = "http://xa--fs-eee.org"; - Fine
  string url = "http://zn--fs-eee.org"; - Fine
  string url = "http://xn--fa-eee.org"; - Error
  string url = "http://xn--faa-eee.org"; - Error
  string url = "http://xn--faaaaaaaaaaaaa-eee.org"; - Error
  string url = "http://xn--faaaaaaaaaaaaaeee.org"; - Fine

有趣的是，如果您在调用“EndGetResponse”之前查看私有字段“_exception”，则异常已经在“EndGetResponse”之前发生。

不出所料，WebClient 也显示了类似的问题：

        const string url = "http://xn--fanbys-exa.org/episodes.m4a.rss";

        var wc = new WebClient();
        wc.DownloadStringCompleted += (o, args) =>
                                          {
                                              Debug.WriteLine(args.Result);
                                          };

        wc.DownloadStringAsync(new Uri(url, UriKind.Absolute));

产量：

  System.Net.WebException was unhandled
    Message=An exception occurred during a WebClient request. 
    StackTrace:
         at System.ComponentModel.AsyncCompletedEventArgs.RaiseExceptionIfNecessary()
         at System.Net.DownloadStringCompletedEventArgs.get_Result()
         at OddballHttp.MainPage.<MainPage_Loaded>b__0(Object o, DownloadStringCompletedEventArgs args)
         at System.Net.WebClient.OnDownloadStringCompleted(DownloadStringCompletedEventArgs e)
         at System.Net.WebClient.DownloadStringOperationCompleted(Object arg)
         at System.Reflection.RuntimeMethodInfo.InternalInvoke(RuntimeMethodInfo rtmi, Object obj, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture, Boolean isBinderDefault, Assembly caller, Boolean verifyAccess, StackCrawlMark& stackMark)
         at System.Reflection.RuntimeMethodInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
         at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
         at System.Delegate.DynamicInvokeOne(Object[] args)
         at System.MulticastDelegate.DynamicInvokeImpl(Object[] args)
         at System.Delegate.DynamicInvoke(Object[] args)
         at System.Windows.Threading.DispatcherOperation.Invoke()
         at System.Windows.Threading.Dispatcher.Dispatch(DispatcherPriority priority)
         at System.Windows.Threading.Dispatcher.OnInvoke(Object context)
         at System.Windows.Hosting.CallbackCookie.Invoke(Object[] args)
         at System.Windows.Hosting.DelegateWrapper.InternalInvoke(Object[] args)
         at System.Windows.RuntimeHost.ManagedHost.InvokeDelegate(IntPtr pHandle, Int32 nParamCount, ScriptParam[] pParams, ScriptParam& pResult)
    InnerException: System.ArgumentException
         Message=""
         StackTrace:
              at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
              at System.Net.Browser.ClientHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
              at System.Net.WebClient.GetWebResponse(WebRequest request, IAsyncResult result)
              at System.Net.WebClient.DownloadBitsResponseCallback(IAsyncResult result)
              at System.Net.Browser.ClientHttpWebRequest.<>c__DisplayClassa.<InvokeGetResponseCallback>b__8(Object state2)
              at System.Threading.ThreadPool.WorkItem.WaitCallback_Context(Object state)
              at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
              at System.Threading.ThreadPool.WorkItem.doWork(Object o)
              at System.Threading.Timer.ring()
         InnerException: System.ArgumentException
              Message=The parameter is incorrect. 
              StackTrace:
                   at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
                   at MS.Internal.XcpImports.WebRequest_Send(InternalWebRequest request)
                   at MS.Internal.InternalWebRequest.Send()
                   at System.Net.Browser.ClientHttpWebRequest.PrepareAndSendRequest(String method, Uri requestUri, Stream requestBodyStream, WebHeaderCollection headerCollection, CookieContainer cookieContainer)
                   at System.Net.Browser.ClientHttpWebRequest.BeginGetResponseImplementation()
                   at System.Net.Browser.ClientHttpWebRequest.InternalBeginGetResponse(AsyncCallback callback, Object state)
                   at System.Net.Browser.ClientHttpWebRequest.BeginGetResponse(AsyncCallback callback, Object state)
                   at System.Net.WebClient.DownloadBits(WebRequest request, Stream writeStream, CompletionDelegate completionDelegate, AsyncOperation asyncOp)
                   at System.Net.WebClient.DownloadStringAsync(Uri address, Object userToken)
                   at System.Net.WebClient.DownloadStringAsync(Uri address)
                   at OddballHttp.MainPage.MainPage_Loaded(Object sender, RoutedEventArgs e)
                   at MS.Internal.CoreInvokeHandler.InvokeEventHandler(Int32 typeIndex, Delegate handlerDelegate, Object sender, Object args)
                   at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, Int32 actualArgsTypeIndex, String eventName)