TCP粘包的拆包處理

 

因為TCP是流式處理的，所以包沒有邊界，必須設計一個包頭，里面表示包的長度（一般用字節表示），根據這個來逐個拆包。如果對於發送/接收頻率不高的話，一般也就不做拆包處理了，因為不大可能有粘包現象。

 

以下是粘包和拆包的分析：

http://blog.csdn.net/zhangxinrun/article/details/6721495

 

用Qt的TCPSocket讀出的數據來拆：

http://www.aiuxian.com/article/p-1732805.html

 

 

我是根據以上鏈接例子Qt的邏輯來實現的，用Boost的ASIO來讀取，是同步的：

m_imp->m_thread = boost::make_shared<boost::thread>(
            [=]()
            {
                while (!boost::this_thread::interruption_requested())
                {
                    boost::this_thread::interruption_point();

                    try
                    {
                        boost::system::error_code ec;
                        std::vector<uint8_t> tmpreadBuffer(1024 * 500);
                        
                        size_t bytes_transferred = m_imp->m_sockPtr->read_some(boost::asio::buffer(tmpreadBuffer), ec);

                        std::cout << "Byte Transfered:" << bytes_transferred << "\n";

                        if (!ec)
                        {
                            
                            if (bytes_transferred == 0)  continue;
                            
                            if (bytes_transferred < MSG_HEAD_SIZE)
                            {
                                m_imp->m_readBuffer.insert(m_imp->m_readBuffer.end(), tmpreadBuffer.begin(), tmpreadBuffer.begin() + bytes_transferred / sizeof(uint8_t));
                                continue;
                            }
                            else
                            {
                                m_imp->m_readBuffer.insert(m_imp->m_readBuffer.end(), tmpreadBuffer.begin(), tmpreadBuffer.begin() + bytes_transferred / sizeof(uint8_t));
                                
                                size_t totalSize = m_imp->m_readBuffer.size()*sizeof(uint8_t);

                                while (totalSize)
                                {
                                    size_t msgSize = m_imp->getMsgLen();
                                    std::cout << "Msg Size is:" << msgSize << "\n";
                                    
                                    std::vector<uint8_t>::const_iterator first = m_imp->m_readBuffer.begin();
                                    std::vector<uint8_t>::const_iterator last = m_imp->m_readBuffer.begin() + msgSize / sizeof(uint8_t);
                                    std::vector<uint8_t> tmpMsg(first, last);

                                    m_imp->m_msgQueue.push_back(tmpMsg);

                                    m_imp->m_readBuffer.erase(first, last);

                                    totalSize = m_imp->m_readBuffer.size()*sizeof(uint8_t);

                                    
                                }

                            }
                            
                            

                           


                        }
                        else
                        {
                            std::cerr << "recv error : RAC module！" << ec.message() << std::endl;
                            m_imp->m_sockPtr->close();
                            break;
                        }
                    }
                    catch (std::exception& e)
                    {
                        std::cerr << e.what() << std::endl;
                        m_imp->m_sockPtr->close();
                        break;
                    }
                }
            }
            
            
            
            );

 

以下一個附帶干貨，以前一直不太理解Qt的TCPSocket，下面是底層原理：

http://blog.csdn.net/ying_593254979/article/details/17006507