尝试捕获异步等待 https 异常

Question

我有一个看起来很奇怪的情况。我有一些异步/等待代码，它使用 RestSharp 从几种目录服务返回的几个休息 API（托管在不同 URL 上的相同 API）获取一些数据。

现在的问题是：所述目录服务返回的 API 之一在某种程度上是“私有的”，并且启动与其的 SSL 连接失败。 Fiddler 捕获以下响应：

HTTP/1.1 200 Connection Established
FiddlerGateway: Direct
StartTime: 19:13:11.117
Connection: close

fiddler.network.https> HTTPS handshake to foo.bar.com failed. System.IO.IOException The handshake failed due to an unexpected packet format.

如果发生这种情况，我最好跳过从该 API 获取数据并继续前进。然而，事实证明 try/catch 没有帮助！抛出 NullReferenceException，但即使是通用的 try/catch 也无法捕获它。

代码非常简单：

try
{
   await GetDataAsync(url);
}
catch 
{
   // never gets called
}

和

private async Task<List<Data>> GetDataAsync(string url)
{
   var request = new RestRequest("/foo");
   var restClient = new RestClient(url);

   var response = await restClient.ExecuteTaskAsync<List<Data>>(request); // <-- this throws 
   return response.Data;
}

我已将代码提取到库中，并在控制台应用程序和 WPF 应用程序中进行了尝试，结果相同，永远不会输入 catch 块。

有什么想法吗？

l.e.：根据要求，这是完整的异常堆栈跟踪

Unhandled Exception: System.NullReferenceException: Object reference not set to
an instance of an object.
at RestSharp.RestClient.<>c__DisplayClass15`1.<ExecuteTaskAsync>b__12(IRestResponse`1 response, RestRequestAsyncHandle _)
at RestSharp.RestClient.DeserializeResponse[T](IRestRequest request, Action`2 callback, IRestResponse response, RestRequestAsyncHandle asyncHandle)
at RestSharp.RestClient.<>c__DisplayClassa`1.<ExecuteAsync>b__9(IRestResponse response, RestRequestAsyncHandle asyncHandle)
at RestSharp.RestClient.ProcessResponse(IRestRequest request, HttpResponse httpResponse, RestRequestAsyncHandle asyncHandle, Action`2 callback)
at RestSharp.RestClient.<>c__DisplayClass3.<ExecuteAsync>b__0(HttpResponse r)
at RestSharp.Http.ExecuteCallback(HttpResponse response, Action`1 callback)
at RestSharp.Http.ResponseCallback(IAsyncResult result, Action`1 callback)
at RestSharp.Http.<>c__DisplayClass3.<GetStyleMethodInternalAsync>b__1(IAsyncResult result)
at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
at System.Net.ContextAwareResult.CompleteCallback(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Net.ContextAwareResult.Complete(IntPtr userToken)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
at System.Net.HttpWebRequest.SetResponse(Exception E)
at System.Net.HttpWebRequest.CheckWriteSideResponseProcessing()
at System.Net.ConnectStream.ProcessWriteCallDone(ConnectionReturnResult returnResult)
at System.Net.HttpWebRequest.WriteCallDone(ConnectStream stream, ConnectionReturnResult returnResult)
at System.Net.ConnectStream.CallDone(ConnectionReturnResult returnResult)
at System.Net.ConnectStream.IOError(Exception exception, Boolean willThrow)
at System.Net.ConnectStream.HandleWriteHeadersException(Exception e, WebExceptionStatus error)
at System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar)
at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
at System.Net.TlsStream.ResumeIOWorker(Object result)
at System.Net.TlsStream.WakeupPendingIO(IAsyncResult ar)
at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
at System.Net.Security.SslState.FinishHandshake(Exception e, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.PartialFrameCallback(AsyncProtocolRequest asyncRequest)
at System.Net.AsyncProtocolRequest.CompleteRequest(Int32 result)
at System.Net.FixedSizeReader.CheckCompletionBeforeNextRead(Int32 bytes)
at System.Net.FixedSizeReader.ReadCallback(IAsyncResult transportResult)
at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
at System.Net.ContextAwareResult.CompleteCallback(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Net.ContextAwareResult.Complete(IntPtr userToken)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
at System.Net.Sockets.BaseOverlappedAsyncResult.CompletionPortCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)

Answer 1

这似乎是a bug in RestSharp。我不确定您是否可以在不修改 RestSharp 的源代码的情况下做任何事情。