记一次Socket编程踩的坑

闲来无事研究了下Socket，想用它做个简单的聊天室模型，结果踩了个坑，整半天才出来，惭愧啊，先上完成的代码吧

服务端：

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            TextBox.CheckForIllegalCrossThreadCalls = false;
        }
        Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        ];
        ];
        List<Socket> clients = new List<Socket>();

        private void btnBeginListen_Click(object sender, EventArgs e)
        {
            if(socket.LocalEndPoint!=null)
            {
                return;
            }
            IPEndPoint ip = new IPEndPoint(IPAddress.Any, int.Parse(tbPort.Text));
            socket.Bind(ip);
            socket.Listen();
            tbReceive.Text += "Begin listening...\r\n";
            Task.Run(()=>BeginListen());
        }

        private void BeginListen()
        {
            while (true)
            {
                Socket client = socket.Accept();
                clients.Add(client);
                IPEndPoint clientIp = client.RemoteEndPoint as IPEndPoint;
                tbReceive.Text += clientIp.Address + ":" + clientIp.Port + " connected...\r\n";
                receiveData = Encoding.UTF8.GetBytes("welcome");
                client.Send(receiveData);
                Task.Run(() => ReceiveMsg(client));
            }
        }
        private void ReceiveMsg(Socket client)
        {
            ;
            do
            {
                try
                {
                    length = client.Receive(receiveData);
                    , length);
                    IPEndPoint ep = (IPEndPoint)client.RemoteEndPoint;
                    tbReceive.Text += ep.Address + ":" + ep.Port + ": " + DateTime.Now.ToString() + "\r\n";
                    tbReceive.Text += stringData + "\r\n";
                }
                catch (SocketException ex)
                {
                    tbReceive.AppendText("远程端关闭.\r\n");
                    clients.Remove(client);
                    return;
                }
                catch(Exception ex)
                {
                    tbReceive.AppendText("异常："+ex.Message);
                }
            }
            );
        }
        private void btnSend_Click(object sender, EventArgs e)
        {
            Socket client = clients[];
            sendData = Encoding.UTF8.GetBytes(tbSend.Text);
            client.Send(sendData, , sendData.Length,SocketFlags.None);
            tbSend.Clear();
        }
    }

客户端：

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            TextBox.CheckForIllegalCrossThreadCalls = false;
        }

        Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        ];
        ];
        private void btnConnect_Click(object sender, EventArgs e)
        {
            if(socket.LocalEndPoint!=null)
            {
                return;
            }
            IPEndPoint ip = new IPEndPoint(IPAddress.Any, int.Parse(tbLocalPort.Text));
            socket.Bind(ip);
            IPEndPoint remoteIp = new IPEndPoint(IPAddress.Parse(tbIp.Text), int.Parse(tbPort.Text));
            try
            {
                socket.Connect(remoteIp);
            }
            catch (Exception ex)
            {
                tbReceive.Text += "无法连接服务器:"+ex.Message;
            }
            Task.Run(() => ReceiveMsg());
        }
        private void ReceiveMsg()
        {
            ;
            do
            {
                try
                {
                    length = socket.Receive(receiveData);
                    , length);
                    IPEndPoint ep = (IPEndPoint)socket.RemoteEndPoint;
                    tbReceive.Text += ep.Address + ":" + ep.Port + ": " + DateTime.Now.ToString() + "\r\n";
                    tbReceive.Text += stringData + "\r\n";
                }
                catch (SocketException ex)
                {
                    tbReceive.AppendText("连接异常.\r\n");
                    return;
                }
                catch (Exception ex)
                {
                    tbReceive.AppendText("异常:" + ex.Message);
                }
            }
            );
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            sendData = Encoding.UTF8.GetBytes(tbSend.Text);
            socket.Send(sendData, , sendData.Length, SocketFlags.None);
            tbSend.Clear();
        }
    }

多线程写textbox的时候需要开启：TextBox.CheckForIllegalCrossThreadCalls = false;

好，下面问题来了：

请注意看这两行代码：

];
];

开始一偷懒把这两个缓冲区用同一个数组来接收，然后坑就来了：

1.当我从服务端往客户端发了个“123”，客户端接到“123”后再往服务端发送“456”，结果服务端接收到的是“123”，再次发送“789”，服务端接收到的是“456”

2.当我从服务端往客户端发了个“123”，客户端接到“123”后再往服务端发送“4567”，结果服务端就报数组index超出范围了

想来想去都想不明白问题出在哪，百度、谷歌、StackOverFlow，都没有找到我要的答案，后来看到一篇文章问Socket的缓冲区为什么要用数组来接，突然灵光一现，也许问题就出在这个缓冲区上了，当我把数组分别定义成两个后，顺利解决问题了。

为啥怎么搜都搜不到这个问题呢，估计是没人跟我一样用同一个数组干过吧，汗。。。

具体的原理还没搞明白，等高手来回答。

巴特西

记一次Socket编程踩的坑

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