数据丢失TCP IP C# [英] Data loss TCP IP C#

问题描述

这是我的代码:

private void OnReceive(IAsyncResult result)
{
NetStateObject state = (NetStateObject)result.AsyncState;

Socket client = state.Socket;

int size = client.EndReceive(result);

byte[] data = state.Buffer;

object data = null;

using (MemoryStream stream = new MemoryStream(data))
{
    BinaryFormatter formatter = new BinaryFormatter();

    data = formatter.Deserialize(stream);
}

//todo: something with data

client.BeginReceive(
    state.Buffer,
    0,
    NetStateObject.BUFFER_SIZE,
    SocketFlags.None,
    OnReceive,
    state
    );
}

state.Buffer的最大大小为NetStateObject.BUFFER_SIZE(1024).首先，这是太大还是太小?其次，如果我发送的内容大于该值，则反序列化会混乱，因为它尝试反序列化的对象没有所有信息(因为并非所有数据都已发送).在尝试构造数据并对数据进行处理之前，如何确保已收到所有数据?

state.Buffer has a maximum size of NetStateObject.BUFFER_SIZE (1024). Firstly, is this too big or too small? Second, if I send something larger than that, my deserialize messes up because the object it is trying to deserialize doesnt have all the information (because not all the data was sent). How do I make sure that all my data has been received before I try to construct it and do something with it?

已完成的工作代码

        private void OnReceive(IAsyncResult result)
    {
        NetStateObject state = (NetStateObject)result.AsyncState;

        Socket client = state.Socket;

        try
        {
            //get the read data and see how many bytes we received
            int bytesRead = client.EndReceive(result);

            //store the data from the buffer
            byte[] dataReceived = state.Buffer;

            //this will hold the byte data for the number of bytes being received
            byte[] totalBytesData = new byte[4];

            //load the number byte data from the data received
            for (int i = 0; i < 4; i++)
            {
                totalBytesData[i] = dataReceived[i];
            }

            //convert the number byte data to a numan readable integer
            int totalBytes = BitConverter.ToInt32(totalBytesData, 0);

            //create a new array with the length of the total bytes being received
            byte[] data = new byte[totalBytes];

            //load what is in the buffer into the data[]
            for (int i = 0; i < bytesRead - 4; i++)
            {
                data[i] = state.Buffer[i + 4];
            }

            //receive packets from the connection until the number of bytes read is no longer less than we need
            while (bytesRead < totalBytes + 4)
            {
                bytesRead += state.Socket.Receive(data, bytesRead - 4, totalBytes + 4 - bytesRead, SocketFlags.None);
            }

            CommandData commandData;

            using (MemoryStream stream = new MemoryStream(data))
            {
                BinaryFormatter formatter = new BinaryFormatter();

                commandData = (CommandData)formatter.Deserialize(stream);
            }

            ReceivedCommands.Enqueue(commandData);

            client.BeginReceive(
                state.Buffer,
                0,
                NetStateObject.BUFFER_SIZE,
                SocketFlags.None,
                OnReceive,
                state
                );

            dataReceived = null;
            totalBytesData = null;
            data = null;
        }
        catch(Exception e)
        {
            Console.WriteLine("***********************");
            Console.WriteLine(e.Source);
            Console.WriteLine("***********************");
            Console.WriteLine(e.Message);
            Console.WriteLine("***********************");
            Console.WriteLine(e.InnerException);
            Console.WriteLine("***********************");
            Console.WriteLine(e.StackTrace);
        }
    }

推荐答案

TCP是一种流协议.它没有数据包的概念.可以在多个数据包中发送单个写调用，并且可以将多个写调用放入同一数据包中.因此，您需要在TCP之上实现自己的打包逻辑.

TCP is a stream protocol. It has no concept of packets. A single write call can be sent in multiple packets, and multiple write calls can be put into the same packet. So you need to implement your own packetizing logic on top of TCP.

有两种常见的打包方法:

There are two common ways to packetize:

1. 定界符，通常用于文本协议中，换行是一种常见选择
2. 为每个数据包添加前缀长度，通常对于二进制协议来说是个不错的选择.

您将逻辑数据包的大小存储在该数据包的开头.然后读取，直到收到足够的字节来填充数据包并开始反序列化.

You store the size of a logical packet at the beginning of that packet. Then you read until you received enough bytes to fill the packet and start deserializing.

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