TCP 客户端消息处理

问题描述

我正在接收一个字节流，我需要拆分消息，例如

I'm receiving a stream of bytes and i need to split out messages, for example

Message1\nMessage2\nMessage3\nMess

每条消息都将附加 '\n' 字符，但是当一个完整的消息无法放入缓冲区时，它会在下一次 recv 调用中获取消息的一部分和另一部分，这可能需要重新分配内存附加消息.

Each message will be appended by '\n' character but when a complete message cannot fit into buffer it gets a part of message and another part of it on next recv call which might require memory reallocations to append the message.

我这样做正确还是有更好的方法来处理消息而不是重新分配缓冲区?

Am i doing this correctly or would there be any better way to handle the messages instead of reallocating buffer?

推荐答案

您可以在消息前面加上消息的长度，然后先阅读.然后分配一个足够大的缓冲区来接收内容，并接收直到读取所需的字节数.

You could prepend the length of your message to the message, and read that first. Then allocate a buffer big enough to recieve the contents, and recv until it's read the required number of bytes.

例如

int len = 0;
if(recv(socket, reinterpret_cast<char*>(&len), sizeof(int), 0) == sizeof(int))
{
    std::vector<char> buffer;
    buffer.resize(len);

    int bytesRead = 0;
    while(bytesRead < len)
    {
        //read as much as we can. note: byteInc may not == len-bytesRead.
        int byteInc = recv(socket, &buffer[bytesRead], len-bytesRead, 0);
        if(byteInc != SOCKET_ERROR)
        {
            bytesRead += byteInc;
        }
        else
        {
            //should probably handle this error properly
            break;
        }
    }

    //buffer now contains the complete message.
    some_processing_function(buffer);
}

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