Boost Asio收到損壞的消息

Question

我做了一個服務器和客戶端異步應用程序。 除我收到的消息外，所有其他方法均正常運行。 我正在將圖像片段發送到字符串中。 但是，當我收到它們時，該字符串已損壞，這與發送的字符串不同。 長度相同，幾乎所有字符。 如果將發送的內容與接收的內容進行比較，我會發現與發送的字符有300個不同的字符。 我正在發送50.000個字符的字符串。 知道可能是什么問題嗎？ 大部分代碼是注釋，因此您將在幾秒鍾內理解它。 另外，我縮小了它的大小，以使您更容易閱讀。

我正在發送。

        // Send a message
        void StartSendMessage ( MessagePtr msg )
        {
            // As long as the queue is not empty, the 'sending agent' is still alive
            bool writeInProgress =! m_messageQueue.empty() ;

            // Queue the message
            m_messageQueue.push ( msg ) ;
            if ( msg -> BodyLength() != 0 )
            {
                std:: cout << "Sending :" << msg -> BodyLength() << std:: endl ;
            }

            // If the 'sending agent' is inactive, start it
            if ( !writeInProgress )
            {           
                // Send message asynchronously. We leave the message on the queue 
                // since it needs to be available during the async read
                async_write ( m_socket , boost::asio::buffer ( msg -> HeaderData() , msg -> SendLength () ) ,
                    boost::bind ( &ASyncConnectionMT::HandleSentMessage , this , boost::asio::placeholders::error , boost::asio::placeholders::bytes_transferred ) ) ;

            }
        }

        // Message was sent
        void HandleSentMessage ( const boost::system::error_code& ec , size_t size )
        {               
            // Check the error code
            if ( ec )
            {
                // Transfer error
                std:: cout << "Error sending message: " << ec.message() << std:: endl ;
                DoStop() ;
                return ;
            }

            // Remove the sent message from queue
            m_messageQueue.pop() ; 

            // If the que is not empty, send next message asynchronously.
            // We leave the message on the que since it needs to be available during the async send
            if ( !m_messageQueue.empty() ) 
            {
                MessagePtr msg = m_messageQueue.front() ;


                std:: cout << "Message send lenght "<< msg->SendLength() ;
                async_write ( m_socket , boost::asio::buffer ( msg -> HeaderData() , msg -> SendLength () ) ,
                    boost::bind ( &ASyncConnectionMT:: HandleSentMessage , this , boost::asio::placeholders::error , boost::asio::placeholders::bytes_transferred ) ) ;
            }
        }

我正在閱讀。

            void StartReceiving()
            {

                // Create receive buffer
                BufferPtr receiveBuffer ( new Buffer ) ;

                // Start async read, must pass 'this' as shared_ptr, else the 
                // 'this' object will be destroyed after leaving this function
                m_socket.async_read_some ( boost::asio::buffer ( *receiveBuffer ) , boost::bind ( &ASyncConnectionMT::HandleReceivedd , shared_from_this() , receiveBuffer , 
                    boost::asio::placeholders::error , boost::asio::placeholders::bytes_transferred ) );
             }

        // Handle received data
        void HandleReceivedd ( BufferPtr receiveBuffer , const boost::system::error_code& ec , size_t size)
        {

            if ( !ec )
            {
                BufferPtr sendBuffer ( new Buffer ) ;

                  std:: cout << m_socket.remote_endpoint() << ": Message received: " << std:: string (receiveBuffer -> data() , size ) << std:: endl << std:: endl; 
                    std:: cout << "Message lenght received " << size << std:: endl;

                // Start receiving next bit
                StartReceiving() ;


            }

            else if ( ec == boost::asio::error::eof)
            {

                // Client disconnected. Close the socket.
                std:: cout << m_socket.remote_endpoint() << ": Connection closed ( handle received )" << std:: endl;
                m_socket.close();
            }


        }

Answer 1

我在這段代碼中看到了幾個問題：

1）發送時，您要將msg 副本放入m_messageQueue 。 但是，當您調用async_write ，緩沖區是從msg而不是m_messageQueue獲取的指針m_messageQueue 。 因此最終您可以從不適當的緩沖區發送。

2）在接收時，您在堆棧上創建了receiveBuffer 。 當async_read_some立即返回（幾乎總是）時，由於您退出StartReceiving調用，所以receiveBuffer將被破壞。

3）與sendBuffer相同