内部服务器上的Httpclient请求返回超时c#

Question

我创建了一个与 slack websocket 连接的 Windows 服务 (c# .net5)。连接首先通过 slackAPI 请求 websocket 地址，然后与 slack 服务器建立连接。我编写了一个代码来获取那个 websocket 地址，它在我的本地机器上运行良好。但是，当我将我的服务应用程序启动到我们的内部 Windows Server 2016 时，该请求会因超时而取消。

The request was canceled due to the configured HttpClient.Timeout of 60 seconds elapsing.
System.Threading.Tasks.TaskCanceledException: The request was canceled due to the configured HttpClient.Timeout of 60 seconds elapsing.
 ---> System.TimeoutException: The operation was canceled.
 ---> System.Threading.Tasks.TaskCanceledException: The operation was canceled.
   at System.Net.Http.ConnectHelper.ConnectAsync(Func`3 callback, DnsEndPoint endPoint, HttpRequestMessage requestMessage, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.GetHttpConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpClient.SendAsyncCore(HttpRequestMessage request, HttpCompletionOption completionOption, Boolean async, Boolean emitTelemetryStartStop, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   --- End of inner exception stack trace ---
   at System.Net.Http.HttpClient.SendAsyncCore(HttpRequestMessage request, HttpCompletionOption completionOption, Boolean async, Boolean emitTelemetryStartStop, CancellationToken cancellationToken)
   at GetWebSocketUrl() in C:\Users\filename.cs:line 130

我尝试将超时时间增加到 5 分钟，但仍然没有成功。 经过一番研究，我发现了这个问题并尝试在我的代码中添加标题（见下文），但仍然没有。 (Why can the C# HttpClient not call this URL (always times out)?)

任何可以帮助我找到解决方案的线索将不胜感激。

using (HttpClient httpClient = new HttpClient())
                {
                    HttpContent content = new StringContent("", Encoding.UTF8, "application/x-www-form-urlencoded");
                    content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");

                    httpClient.Timeout = TimeSpan.FromMinutes(1);
                    httpClient.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko; Google Page Speed Insights) Chrome/27.0.1453 Safari/537.36");
                    httpClient.DefaultRequestHeaders.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/apng,*/*;q=0.8");
                    httpClient.DefaultRequestHeaders.Add("Connection", "keep-alive");
                    httpClient.DefaultRequestHeaders.Add("Accept-Language", "en-US,en;q=0.9");
                    httpClient.DefaultRequestHeaders.Add("Accept-Encoding", "gzip, deflate, br");
                    httpClient.DefaultRequestHeaders.Add("Cache-Control", "no-cache");
                    httpClient.DefaultRequestHeaders.Add("Pragma", "no-cache");
                    httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", SLACK_TOKEN);
                    HttpResponseMessage response = await httpClient.PostAsync(SLACK_URI, content);
                    string bodyResponseString = await response.Content.ReadAsStringAsync();
                    dynamic jsonBody = JsonConvert.DeserializeObject(bodyResponseString);

                    if (jsonBody["ok"] == "True")
                    {
                        return jsonBody["url"];
                    }
                }

Answer 1

原来是代理问题。只需要在 httpClient 上添加代理就可以了。

        IWebProxy _proxyConfig = new WebProxy
        {
            Address = new Uri($"{proxyIp}:{proxyPort}"),
            BypassProxyOnLocal = false,
            UseDefaultCredentials = true,
        };
        HttpClientHandler httpClientHandler = new HttpClientHandler
        {
            Proxy = _proxyConfig,
        };
        using (HttpClient _client = new HttpClient(handler: httpClientHandler)) {...}