“错误：在已连接的套接字上发出了连接请求”

Question

I am trying to write a program which will request certain pieces of information, for example the internal temperature, from a camera which acts as a server, sorry if my terminology is off, but basically what I mean is that communication with the camera is achieved through HTTP get requests. The program essentially just calls an slightly adapted version async_client from the boost library passing in a different path each time to check a different value, then compares the returned value to ensure it sounds reasonable before passing in a different path to check something else.

The code seems to work correctly the first time round, but on the second attempt it gets to the handle_connect function and outputs "Error: A connect request was made on an already connected socket"

Here is what the function looks like:

void Async_client::handle_connect(const boost::system::error_code& err, tcp::resolver::iterator endpoint_iterator)
  {
        http_deadline_timer_.cancel();
        if (!err)
        {
            // The connection was successful. Send the request.
            boost::asio::async_write(socket_, request_, boost::bind(&Async_client::handle_write_request, this,
              boost::asio::placeholders::error));
            //deadline timer stuff
            http_deadline_timer_.expires_from_now( ::boost::posix_time::seconds(1));
            http_deadline_timer_.async_wait( ::boost::bind(&Async_client::call_handle_deadline_timeout, this, boost::asio::placeholders::error));
        }
        else if (endpoint_iterator != tcp::resolver::iterator())
        {
            // The connection failed. Try the next endpoint in the list.
            socket_.close();
            tcp::endpoint endpoint = *endpoint_iterator;
            socket_.async_connect(endpoint, boost::bind(&Async_client::handle_connect, this,
              boost::asio::placeholders::error, ++endpoint_iterator));
            //deadline timer stuff
            http_deadline_timer_.expires_from_now( ::boost::posix_time::seconds(1));
            http_deadline_timer_.async_wait( ::boost::bind(&Async_client::call_handle_deadline_timeout, this, boost::asio::placeholders::error));
        }
        else
        {
            LOG_WARN("Async_client.cpp: Error: " << err.message()); 
        }
  }

I tried copying this section of code from the else if statement into the else statement as well thinking that it would close the socket and re-run the handle_connect function, but it just seems to crash to software on endpoint= *endpoint_iterator line.

socket_.close();
            tcp::endpoint endpoint = *endpoint_iterator;
            socket_.async_connect(endpoint, boost::bind(&Async_client::handle_connect, this,
              boost::asio::placeholders::error, ++endpoint_iterator));

Does anyone have any idea what I should do in this situation? Disconnect the socket and reconnect? If so how do I do this?

Answer 1

也许将SO_REUSEADDR选项与setsockopt可能会有所帮助。