c# - 搭建C#异步TCP代理服务器

Question

我正在尝试为我的企业构建一个简单的 C# TCP 代理，这样我就可以阻止我的员工访问某些网站。一切都很好，除了我无法查看用户尝试访问的网站...我可以看到用户已连接到我的代理服务器，所以我知道我正在建立连接，但 OnRecieve 回调甚至没有触发。我从套接字读取错误吗？

这是我的代码:

internal class AsyncState
{
    public const int BufferSize = 4096;
    public byte[] Buffer = new byte[AsyncState.BufferSize];
    public Socket Socket;
    public StringBuilder Content = new StringBuilder();
}

private void OnLoad(object sender, EventArgs e)
{
    IPAddress[] addressCollection = Dns.GetHostAddresses(Dns.GetHostName());
    foreach (IPAddress ipAddress in addressCollection)
    {
        if (ipAddress.AddressFamily == AddressFamily.InterNetwork)
        {
            localEndPoint = new IPEndPoint(ipAddress, 8080);
            Console.WriteLine("Local IP address found... " + localEndPoint.ToString());
            break;
        }
    }

    isListening = true;

    thread = new Thread(new ThreadStart(
        delegate()
        {
            serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            serverSocket.Bind(localEndPoint);
            serverSocket.Listen(10);

            while (isListening)
            {
                resetEvent.Reset();

                Console.WriteLine("Waiting for clients...");
                serverSocket.BeginAccept(new AsyncCallback(OnAccept), serverSocket);

                resetEvent.WaitOne();
                }
            }));

        thread.Start();
    }
}

private void OnAccept(IAsyncResult result)
{
    resetEvent.Set();

    Socket clientSocket = (result.AsyncState as Socket).EndAccept(result);
    Console.WriteLine("Client has connected... " + clientSocket.RemoteEndPoint.ToString());

    AsyncState state = new AsyncState();
    state.Socket = clientSocket;
    state.Socket.BeginReceive(state.Buffer, 0, AsyncState.BufferSize, SocketFlags.None, new AsyncCallback(OnRecieve), state);
}

private void OnRecieve(IAsyncResult result)
{
    AsyncState state = result.AsyncState as AsyncState;

    int totalRead = state.Socket.EndReceive(result);
    if (totalRead > 0)
    {
        state.Content.Append(Encoding.ASCII.GetString(state.Buffer, 0, totalRead));
        state.Socket.BeginReceive(state.Buffer, 0, AsyncState.BufferSize, SocketFlags.None, new AsyncCallback(OnRecieve), state);
    }
    else
    {
        if (state.Content.Length > 1)
            Console.WriteLine("Message recieved from client... " + state.Content.ToString());

        state.Socket.Close();
    }
}

Answer 1

构建一个运行良好的代理绝非易事，因为您必须在两个方向上理解和处理 HTTP 等...

我建议为此使用现有的库或一些可配置的代理...

• http://www.mentalis.org/soft/projects/proxy/ (带来源)
• http://sourceforge.net/p/portfusion/home/PortFusion/ (带来源)
• http://www.wingate.com/
• http://www.squid-cache.org/

备注:

我不知道你在哪个司法管辖区，但在员工不知情/不同意的情况下使用此类技术在某些地方可能会成为问题......

另一点:我不会使用这种方法，而是告诉员工停止滥用公司的互联网连接 1-3 次，如果这不起作用，我宁愿解雇那个人......这样的员工不仅是滥用公司的互联网连接，但在最坏的情况下会使公司处于危险之中(病毒/木马等)并且还会欺骗公司(如果他在工作时间这样做)...