c# - index 和 count 必须引用缓冲区中的位置。参数名称字节

Question

它抛出一个索引并且计数必须引用缓冲区中的一个位置。当超过 3 个客户端连接到服务器时，参数名称字节异常 & 字节数据被声明为全局变量。

private void OnReceive(IAsyncResult ar)        
{           
    try
    {
        clientSocket.EndReceive(ar);

        Data msgReceived = new Data(byteData);
        //Accordingly process the message received
        switch (msgReceived.cmdCommand)
        {
            case Command.Login:
                //lstChatters.Items.Add(msgReceived.strName);
                break;

            case Command.Logout:
                lstChatters.Items.Remove(msgReceived.strName);
                break;

            case Command.Message:
                break;

            case Command.List:
                lstChatters.Items.AddRange(msgReceived.strMessage.Split('*'));
                lstChatters.Items.RemoveAt(lstChatters.Items.Count - 1);
                txtChatBox.Text += "<<<" + strName + " has joined the room>>>\r\n";
                break;
        }

        if (msgReceived.strMessage != null && msgReceived.cmdCommand != Command.List)
            txtChatBox.Text += msgReceived.strMessage + "\r\n";

        byteData = new byte[1024];

        clientSocket.BeginReceive(byteData,
                                  0,
                                  byteData.Length,
                                  SocketFlags.None,
                                  new AsyncCallback(OnReceive),
                                  null);

    }
    catch (ObjectDisposedException)
    { }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message, "ClientTCP: " + strName, MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
}

这是用于管理服务器和客户端之间数据通信的类数据:

class Data
{
    //Default constructor
    public Data()
    {
        this.cmdCommand = Command.Null;
        this.strMessage = null;
        this.strName = null;
    }

    //Converts the bytes into an object of type Data
    public Data(byte[] data)
    {
        //The first four bytes are for the Command
        this.cmdCommand = (Command)BitConverter.ToInt32(data, 0);

        //The next four store the length of the name
        int nameLen = BitConverter.ToInt32(data, 4);

        //The next four store the length of the message
        int msgLen = BitConverter.ToInt32(data, 8);

        //This check makes sure that strName has been passed in the array of bytes
        if (nameLen > 0)
            this.strName = Encoding.UTF8.GetString(data, 12, nameLen);
        else
            this.strName = null;

        //This checks for a null message field
        if (msgLen > 0)
            this.strMessage = Encoding.UTF8.GetString(data, 12 + nameLen, msgLen);
        else
            this.strMessage = null;
    }

    //Converts the Data structure into an array of bytes
    public byte[] ToByte()
    {
        List<byte> result = new List<byte>();

        //First four are for the Command
        result.AddRange(BitConverter.GetBytes((int)cmdCommand));

        //Add the length of the name
        if (strName != null)
            result.AddRange(BitConverter.GetBytes(strName.Length));
        else
            result.AddRange(BitConverter.GetBytes(0));

        //Length of the message
        if (strMessage != null)
            result.AddRange(BitConverter.GetBytes(strMessage.Length));
        else
            result.AddRange(BitConverter.GetBytes(0));

        //Add the name
        if (strName != null)
            result.AddRange(Encoding.UTF8.GetBytes(strName));

        //And, lastly we add the message text to our array of bytes
        if (strMessage != null)
            result.AddRange(Encoding.UTF8.GetBytes(strMessage));

        return result.ToArray();
    }

    public string strName;      //Name by which the client logs into the room
    public string strMessage;   //Message text
    public Command cmdCommand;  //Command type (login, logout, send message, etcetera)
}

Answer 1

要解决第一个 问题，不要让byteData 成为全局的。改为本地化:

private void OnReceive(IAsyncResult ar)        
{          
    byte[] byteData;

然后，将其作为 state 参数传递给 BeginReceive :

 byteData = new byte[1024]; //Line 1

 clientSocket.BeginReceive(byteData,
                                      0,
                                      byteData.Length,
                                      SocketFlags.None,
                                      new AsyncCallback(OnReceive),
                                      byteData);

然后从 IAsyncResult 中恢复它在您完成接收后使用它之前:

clientSocket.EndReceive(ar);
byteData = (byte[])ar.AsyncState;

Data msgReceived = new Data(byteData); //Line2

---

当然，解决了这个问题后，您仍然遇到我在评论中提到的另一个问题 - 无法保证有多少数据将返回到缓冲区中 - 您需要检查 EndReceive 的返回值.您可能必须组合多次调用 Receive(或它的道德等价物)，直到您真正建立一条消息。在一端调用 Send 和在另一端调用 Receive 之间没有一对一的对应关系。

最后，您已经表明您正在使用 TcpClient，但您正在使用来自 Socket 类的操作？为什么您不使用 TcpClient 提供的 NetworkStream？ (并不是说它在这里有太大的不同)。