UWP 模拟Ping 请求服务器状态

  笔者近期作的服务器监控UWP小程序，结果发如今UWP程序的.NET命名空间下取消了Ping的部分，看了诸多资料，以为多是.NET 4.5 Framework 暂时不支持ICMP。因而笔者想着经过Socket（命名空间保留了的部分）走上层模拟Ping请求，不过这种方式并不能彻底达到效果，缘由在于Socket创建链接是须要终结点的，即IP+端口号，而实际上ICMP请求是不须要端口号的，直接经过发送ICMP询问报文获取服务器状态便可。

  摘记笔者实现的简易Ping方法：

/// <summary>
        /// 以数据报的消息格式请求链接服务器
        /// </summary>
        /// <param name="desEndPoing">终结点</param>
        /// <returns></returns>
        public static async Task<Tuple<string, string, string, string>> DatagramSocketConnect(IPEndPoint desEndPoing)
        {
            // 请求状态
            string requestStatus = "";
            // 请求耗时
            string requestCost = "";
            // 请求结果
            string color = "";
            // 请求的额外信息
            string others = "";

            // 用来记录请求耗时
            var s = new System.Diagnostics.Stopwatch();
            s.Start();

            try
            {
                // 使用数据报进行消息传输
                using (var UdpClient = new DatagramSocket())
                {
                    // 超时控制
                    CancellationTokenSource cts = new CancellationTokenSource();
                    cts.CancelAfter(1000);                   
                    // HostName 构造须要一个主机名orIP地址(不带http!)
                    // 异步创建链接
                    await UdpClient.ConnectAsync(
                        new Windows.Networking.HostName(desEndPoing.Address.ToString()),
                        desEndPoing.Port.ToString())
                        // 做为Task任务，添加超时令牌
                        .AsTask(cts.Token);
                    // 停表
                    s.Stop();
                    var remoteIp = UdpClient.Information.RemoteAddress;
                    Debug.WriteLine(String.Format("Success, remote server contacted at IP address {0},and the connecting work cost {1} millsseconds!", 
                        remoteIp, s.ElapsedMilliseconds));

                    #region 修改返回数据
                    requestStatus = "200";
                    requestCost = s.ElapsedMilliseconds.ToString();
                    color = "green";
                    others = String.Format("Success, remote server contacted at IP address {0},and the connecting work cost {1} millsseconds!", 
                        remoteIp, s.ElapsedMilliseconds);

                    #endregion
                    // 释放链接
                    UdpClient.Dispose();
                    return new Tuple<string, string, string, string>(requestStatus, requestCost, color, others);
                }
            }
            // 捕获自定义超时异常
            catch (TaskCanceledException)
            {
                #region 修改返回数据
                requestStatus = "1000";
                requestCost = s.ElapsedMilliseconds.ToString();
                color = "orange";
                others = "Error: Timeout when connecting (check hostname and port)";
                #endregion
                return new Tuple<string, string, string, string>(requestStatus, requestCost, color, others);
            }
            // 捕获常见的异常
            catch (Exception ex)
            {
                s.Stop();
                // 查不到对应HostName的服务器
                if (ex.HResult == -2147013895)
                {
                    #region 修改返回数据
                    requestStatus = "0";
                    requestCost = s.ElapsedMilliseconds.ToString();
                    color = "red";
                    others = "Error: No such host is known";
                    #endregion
                    Debug.WriteLine("Error: No such host is known");
                }
                // 请求超时
                else if (ex.HResult == -2147014836)
                {
                    #region 修改返回数据
                    requestStatus = "1000";
                    requestCost = s.ElapsedMilliseconds.ToString();
                    color = "orange";
                    others = "Error: Timeout when connecting (check hostname and port)";
                    #endregion
                    Debug.WriteLine("Error: Timeout when connecting (check hostname and port)");
                }
                // 其余异常
                else
                {
                    #region 修改返回数据
                    requestStatus = "0";
                    requestCost = s.ElapsedMilliseconds.ToString();
                    color = "red";
                    others = "Error: Exception returned from network stack: " + ex.Message;
                    #endregion
                    Debug.WriteLine("Error: Exception returned from network stack: " + ex.Message);
                }
                return new Tuple<string, string, string, string>(requestStatus, requestCost, color, others);
            }
        }

  上述实现方式中几个重要须要注意的点：

• 方法体异步(async + await)
• 异常捕获处理(可能还存在笔者未捕获到的异常)
• 笔者代码中加入了人为超时判断，实际上使用DatagramSocket会本身有超时判断，大概是5s左右

  上面笔者是用的DatagramSocket实现的，实际上还有不少种Socket也能够实现：MessageWebSocket、StreamSocket等等

OK，就先记录到这!