Question

i have a problem with data transfert in boost::asio.
with the following code :

Server.cpp

void        Server::accept(void)
{
    Network::ptr connection = Network::create(this->my_acceptor.get_io_service());
    this->my_acceptor.async_accept(connection->getSocket(), bind(&Server::endCmd, this, connection, placeholders::error));
}

void        Server::endCmd(Network::ptr connection, const boost::system::error_code& error)
{
    if (!error)
        {
            connection->Swrite("BIENVENUE");
            this->accept();
        }
}

Network.cpp

void        Network::Sread(void)
{
    async_read(this->socket, buffer(this->rbuffer), bind(&Network::endRead, shared_from_this(), placeholders::error));
}

void            Network::endRead(const error_code& error)
{
    if (!error)
        {
            this->rcv_msg = this->rbuffer.c_array();
            std::cout << this->rcv_msg << std::endl;
            this->Sread();
        }
}

void            Network::Swrite(std::string msg)
{
    this->msg = msg;
    async_write(this->socket, buffer(this->msg, (int)this->msg.size()), bind(&Network::endWrite, shared_from_this(), placeholders::error));
}

void            Network::endWrite(const error_code &error)
{
    if (!error)
    {
        this->Sread();
    }
}

tcp::socket&    Network::getSocket(void)
{
    return (this->socket);
}

Network::ptr                Network::create(io_service &ios)
{
    return (ptr(new Network(ios)));
}

When i send a string like “Hello world” to the server with telnet, he write the following content :

Who can tell me why the server is writting many unknow characters ?

Answer 1

It looks like the rbuffer.c_array() isn’t a null terminated string but just a array of characters. Printing a character array to cout assumes that the array is null terminated, which in this case causes the memory after the end of the array being included in the output.

You should create a std::string from the data before trying to print it:

std::string received(rbuffer.c_array(), rbuffer.size());
std::cout << received;

(Assuming rbuffer has a size() method or something equivalent)