Async read for tcp server print the data sent by the socket of the client with boost::asio

Question

I want to print the message sent by the client. But in my function handleRead, when get the data from buffer and print it , nothing is print. I don't know how to do it.

void    Network::start()
{
    boost::asio::async_write(m_socket, boost::asio::buffer(m_message),
                             boost::bind(&Network::handleWrite,shared_from_this(),
                                         boost::asio::placeholders::error));
}

void    Network::handleWrite(const boost::system::error_code &error)
{
    if (!error)
            doRead();
    else
            std::cout << error.message() << std::endl;
}

void    Network::handleRead(const boost::system::error_code &error)
    {
    if (!error) {
            std::cout << m_buffer.data()<< std::endl;
            doRead();
    }
    else
            close();
}

void    Network::doRead()
{
    boost::asio::async_read(m_socket,
                            boost::asio::buffer(m_buffer),
                            boost::bind(&Network::handleRead,
                                        shared_from_this(),
                                        boost::asio::placeholders::error));
}

Answer 1

What is the type of m_buffer? If it's a container, you have to resize it in advance. If it's asio::streambuf you need to at least use the bytes_transferred parameter recevied handleRead.

There are many echo examples, so let me just point you at a few:

• https://www.boost.org/doc/libs/1_68_0/doc/html/boost_asio/example/cpp11/echo/async_tcp_echo_server.cpp
• boost asio simple echo server without class
• Boost asio, single TCP server, many clients

Answer 2

The async_read doen't print the message until the size of the buffer is full !