如何在 TCP 客户端（套接字）上在 VB.NET 中实现 TCP KeepAlive答案

【问题标题】：How to implement TCP KeepAlive in VB.NET on a TCP Client(socket)如何在 TCP 客户端（套接字）上在 VB.NET 中实现 TCP KeepAlive
【发布时间】：2012-05-04 18:37:12
【问题描述】：

我想实现 TCP KeepAlive，以便通过运行计时器来检查断开的连接。

就我而言，我有一个 TCP 客户端（使用套接字类）和一个第三方服务器（我无法控制它）。如何在我的 TCP 客户端上使用 TCP KeepAlive 来检查连接状态？

目前我已启用 TCP KeepAlive 选项！

tcpsocket.Connect(IPEndPoint)
tcpSocket.SetSocketOption(SocketOptionLevel.Tcp,SocketOptionName.KeepAlive,1);

在互联网上搜索我发现这个程序应该可以工作，但我想知道如何在我的 TCP 客户端中使用它？

Private Shared Function SetKeepAlive(ByRef tcpSocket As Socket, ByVal keepAliveTime As UInteger, ByVal keepAliveInterval As UInteger) As Boolean
  ' Pack three params into 12-element byte array; not sure about endian issues on non-Intel
  Dim SIO_KEEPALIVE_VALS(11) As Byte
  Dim keepAliveEnable As UInteger = 1
  If (keepAliveTime = 0 Or keepAliveInterval = 0) Then keepAliveEnable = 0
  ' Bytes 00-03 are 'enable' where '1' is true, '0' is false
  ' Bytes 04-07 are 'time' in milliseconds
  ' Bytes 08-12 are 'interval' in milliseconds
  Array.Copy(BitConverter.GetBytes(keepAliveEnable),  0, SIO_KEEPALIVE_VALS, 0, 4)
  Array.Copy(BitConverter.GetBytes(keepAliveTime),   0, SIO_KEEPALIVE_VALS, 4, 4)
  Array.Copy(BitConverter.GetBytes(keepAliveInterval), 0, SIO_KEEPALIVE_VALS, 8, 4)

  Try
   Dim result() As Byte = BitConverter.GetBytes(CUInt(0)) ' Result needs 4-element byte array?
   tcpSocket.IOControl(IOControlCode.KeepAliveValues, SIO_KEEPALIVE_VALS, result)
  Catch e As Exception
   Return False
  End Try
  Return True
 End Function

任何帮助将不胜感激。

PS：我是编程新手，所以请原谅我的编码错误。

【问题讨论】：

标签： .net vb.net sockets tcpclient keep-alive

【解决方案1】：

最后我设法使用了 TCP KeepAlive。所以为了实现这一点，我刚刚在 mainform_load 过程中调用了：

        tcpSocket = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
        tcpSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, True)
        SetKeepAlive(tcpSocket, keepalivetime, keepaliveinterval)
        Try
            tcpSocket.Connect(ipEndPoint)
        Catch e As SocketException
            ...
        End Try

我已与 WireShark 核对过，我注意到已发送的包裹。

【讨论】：