boost :: asio :: ip :: tcp :: socket不會讀取任何內容

Question

這實際上是我在套接字編程中的第一個程序，而不是復制粘貼教程代碼並獲得樂趣。 無論如何，它不起作用。 我想我已經仔細閱讀了文檔，但可能還不夠。 我懷疑我在read_message()使用了socket::read_some() ，因為有問題的程序在閱讀部分停止了。 我認為我使用它的方式應該沒問題，因為socket::read_some()的文檔指出：“該函數調用將阻塞，直到成功讀取一個或多個字節的數據或發生錯誤為止。” 下面是我的代碼。 任何幫助表示贊賞。

void read_message(std::string& message, boost::asio::ip::tcp::socket& socket)
{
    std::stringstream message_stream;
    while (true)
    {
        std::array<char, 128> buffer;
        boost::system::error_code error;
        size_t len = socket.read_some(boost::asio::buffer(buffer), error);
        if (error == boost::asio::error::eof)
        {
            break;
        }
        message_stream.write(buffer.data(), len);
    }
    message = message_stream.str();
}

server.cpp

int main()
{
    while (true)
    {
        boost::asio::io_service io_service;
        boost::asio::ip::tcp::acceptor acceptor(io_service, boost::asio::ip::tcp::endpoint(
            boost::asio::ip::tcp::v4(), 9999));
        boost::asio::ip::tcp::socket socket(io_service);
        acceptor.accept(socket);
        std::cout << "connected with client, waiting for a message\n";
        std::string message;
        read_message(message, socket);
        boost::asio::ip::tcp::endpoint endpoint = socket.remote_endpoint();
        std::cout << "message received from " << endpoint.address().to_string() <<
            ':' << endpoint.port() << '\n' << message << '\n';
        boost::asio::write(socket, boost::asio::buffer(message));
        if (message.compare("quit") == 0)
        {
            break;
        }
    }
    return EXIT_SUCCESS;
}

client.cpp

int main()
{
    while (true)
    {
        std::cout << "your message to be sent: ";
        std::string message;
        std::getline(std::cin, message);
        boost::asio::io_service io_service;
        boost::asio::ip::tcp::resolver resolver(io_service);
        boost::asio::ip::tcp::resolver::query query("localhost", "9999");
        boost::asio::ip::tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
        boost::asio::ip::tcp::socket socket(io_service);
        boost::asio::connect(socket, endpoint_iterator);
        std::cout << "connected to server\n";
        boost::asio::write(socket, boost::asio::buffer(message));
        read_message(message, socket);
        std::cout << "message received from server: " << message << '\n';
        if (message.compare("quit") == 0)
        {
            break;
        }
    }
    return EXIT_SUCCESS;
}

Answer 1

問題出在read_message函數中：您讀到eof ，但是只有在套接字關閉時才能得到eof 。

也許您打算在遇到某些分隔符時從read_message返回，例如。 '\\ N'？ 然后，您可以手動檢查緩沖區，也可以使用read_until函數。

使用read_until函數， read_message將如下所示：

void read_message(std::string& message, boost::asio::ip::tcp::socket& socket)
{
  std::stringstream message_stream;
  boost::asio::streambuf buffer;
  boost::system::error_code error;
  size_t len = read_until(socket, buffer, '\n', error);
  if (len)
  {
    message_stream.write(boost::asio::buffer_cast<const char *>(buffer.data()), len);
    message = message_stream.str();
  }
}

請記住在您從客戶端發送的消息后附加“ \\ n”：

//...
std::cout << "connected to server\n";
boost::asio::write(socket, boost::asio::buffer(message + '\n'));
read_message(message, socket);
//...