转载：http://blog.csdn.net/educast/article/details/13167847

以下代码主要工作在连接后首次接收客户端消息的环节添加一个timer，并在指定时间后检测是否已接收到消息(验证消息环节此处略去)，如果没有收到消息则可认为这是一个非正常连接，并马上断开。timer使用boost::asio::deadline_timer，相对比较简单，详情如下：

#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/date_time/posix_time/posix_time_types.hpp>
#include <boost/shared_ptr.hpp>
#include <iostream>using namespace boost::asio;
using boost::asio::ip::tcp;class Session : public boost::enable_shared_from_this<Session>
{
public:Session(boost::asio::io_service& io_service):timer_(io_service),socket_(io_service),is_read_(false){Start();}void Start(){socket_.async_read_some(boost::asio::buffer(buff,1024),bind(&Session::HandleRead,shared_from_this(),boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred));//当客户端连接上5秒钟以后检测是否进行了通信
        timer_.expires_from_now(boost::posix_time::seconds(5));timer_.async_wait(boost::bind(&Session::time_out, shared_from_this()));}void HandleRead(const boost::system::error_code& error, size_t len){if (!error){is_read_ = true;cout << buff << endl;socket_.async_read_some(boost::asio::buffer(buff,1024),bind(&Session::HandleRead,shared_from_this(),boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred));}}
private:void time_out(){//判断没有从客户端读取到消息的情况下断开连接
        if(!is_read_) socket_.close();}private:deadline_timer timer_;tcp::socket socket_;char buff[1024];bool is_read_;
};