應用場景是這樣的：
客戶端和服務器在不同的網段內，它們之間不能直接通過TCP連接，但是有一臺機器（暫時稱為轉發器）有雙網卡，兩塊網卡分別在客戶端和服務器端的網段內，這樣轉發器就能分別和客戶端即服務器建立連接，并來回傳輸數據。
設計思路是這樣的：
當客戶端連接到轉發器后，轉發器馬上建立一條到服務器之間的連接，與服務器端的連接建立后，就同時異步地從客戶端和服務器端接收數據到兩個緩沖區
中，一旦任何一方有數據接收，就通過另外一條連接將數據發送到另一方，發送完畢后又開始新一輪的數據接收。如果在接收數據的過程中有任何一方出現錯誤，就
將取消另外一條連接的異步調用，這樣整個連接就會關閉。
其中用到了Boost庫的以下特性：
1.Asio的異步IO調用
2.多線程
3.share_ptr的自動指針管理
遺留的一些問題：
由于采用了多線程，為了保險起見，我將每個回調函數都用strand包裹起來，在各回調函數沒有使用共享資源的情況下并不必要，因此在這方面可以優化下
1 /*
2 * =====================================================================================
3 *
4 * Filename: xproxy_main.cpp
5 *
6 * Description:
7 *
8 * Version: 1.0
9 * Created: 2009年11月26
日 15時10分29秒
10 * Revision: none
11 * Compiler: gcc
12 *
13 * Author: David Fang (A free programmer), qi_fd@163.com
14 * Company: nocompany
15 *
16 * =====================================================================================
17 */
18
19 #include <iostream>
20 #include <string>
21 #include <boost/asio.hpp>
22 #include "xproxy_server.hpp"
23
24 int main(int argc, char* argv[])
25 {
26 try
27 {
28 if(5 != argc)
29 {
30 std::cerr<<"Usage: xproxy <local port> <server ip> <server_port> <[thread size>\n";
31 std::cerr<<"local port: local port used to accept login client\n";
32 std::cerr<<"server ip: analysing server address, ip string in decimal dot format\n";
33 std::cerr<<"server port: analysing server port, an unsigned short value\n";
34 std::cerr<<"thread size: number of threads to running xproxy server\n";
35 return 1;
36 }
37 xproxy_server srv(atoi(argv[1]), argv[2], atoi(argv[3]), atoi(argv[4]));
38
39 srv.run();
40 }
41 catch(std::exception& e)
42 {
43 std::cerr<<"exception: "<<e.what()<<"\n";
44 }
45
46 return 0;
47 }
1 /*
2 * =====================================================================================
3 *
4 * Filename: xproxy_server.hpp
5 *
6 * Description:
7 *
8 * Version: 1.0
9 * Created: 2009年11月26
日 15時12分01秒
10 * Revision: none
11 * Compiler: gcc
12 *
13 * Author: David Fang (A free programmer), qi_fd@163.com
14 * Company: nocompany
15 *
16 * =====================================================================================
17 */
18 #ifndef XPROXY_SERVER_HPP
19 #define XPROXY_SERVER_HPP
20
21 #include <string>
22
23 #include <boost/asio.hpp>
24 #include <boost/noncopyable.hpp>
25 #include <boost/shared_ptr.hpp>
26 #include "xproxy_connection.hpp"
27
28 using boost::asio::ip::tcp;
29
30 class xproxy_server:private boost::noncopyable
31 {
32 public:
33
34 //construction of xproxy_server, which takes the destination machine(analysing server)'s
35
36 //address and port(ipv4) as arguments
37
38 explicit xproxy_server(unsigned short local_port, const std::string& ana_address, unsigned short ana_port,
39 std::size_t thread_pool_size = 1);
40
41 //Run the server's io_service loop
42
43 void run();
44
45 //Stop the server
46
47 void stop();
48 private:
49 //Handle the completion of an asynchronous accept from the login client
50
51 void handle_accept(const boost::system::error_code& e);
52
53 //The number of threads that will call io_service::run()
54
55 std::size_t thread_pool_size_;
56
57 //The io_service used to perform asynchronous operations.
58
59 boost::asio::io_service io_service_;
60
61 //Acceptor used to listen for incoming proxy connectins
62
63 boost::asio::ip::tcp::acceptor acceptor_;
64
65 //Local endpoint corresponding to the login client
66
67 tcp::endpoint local_endpoint_;
68
69 //The endpoint to analysing server
70
71 tcp::endpoint analysing_server_endpoint_;
72
73 //The next connectin to be accepted.
74
75 xproxy_connection_ptr new_connection_;
76 };
77
78 #endif
1 /*
2 * =====================================================================================
3 *
4 * Filename: xproxy_server.cpp
5 *
6 * Description:
7 *
8 * Version: 1.0
9 * Created: 2009年11月26
日 15時12分07秒
10 * Revision: none
11 * Compiler: gcc
12 *
13 * Author: David Fang (A free programmer), qi_fd@163.com
14 * Company: nocompany
15 *
16 * =====================================================================================
17 */
18
19 #include "xproxy_server.hpp"
20 #include <boost/thread.hpp>
21 #include <boost/bind.hpp>
22 #include <boost/shared_ptr.hpp>
23 #include <vector>
24
25 xproxy_server::xproxy_server(unsigned short local_port,
26 const std::string& ana_address,
27 unsigned short ana_port,
28 std::size_t thread_pool_size)
29 :thread_pool_size_(thread_pool_size),
30 acceptor_(io_service_),
31 local_endpoint_(tcp::v4(), local_port),
32 analysing_server_endpoint_(boost::asio::ip::address::from_string(ana_address), ana_port),
33 new_connection_(new xproxy_connection(io_service_, analysing_server_endpoint_))
34 {
35 acceptor_.open(local_endpoint_.protocol());
36 acceptor_.set_option(tcp::acceptor::reuse_address(true));
37 acceptor_.bind(local_endpoint_);
38 acceptor_.listen();
39 acceptor_.async_accept(new_connection_->login_clt_sock(),
40 boost::bind(&xproxy_server::handle_accept, this,
41 boost::asio::placeholders::error));
42 }
43
44 void xproxy_server::run()
45 {
46 std::vector<boost::shared_ptr<boost::thread> > threads;
47 for(std::size_t i = 0; i < thread_pool_size_; ++i)
48 {
49 boost::shared_ptr<boost::thread> thread(new boost::thread(
50 boost::bind(&boost::asio::io_service::run, &io_service_)));
51 threads.push_back(thread);
52 }
53
54 for(std::size_t i = 0; i < threads.size(); ++i)
55 {
56 threads[i]->join();
57 }
58 }
59
60 void xproxy_server::stop()
61 {
62 io_service_.stop();
63 }
64
65 void xproxy_server::handle_accept(const boost::system::error_code& e)
66 {
67 if(!e)
68 {
69 new_connection_->start();
70 new_connection_.reset(new xproxy_connection(io_service_,
71 analysing_server_endpoint_));
72
73 acceptor_.async_accept(new_connection_->login_clt_sock(),
74 boost::bind(&xproxy_server::handle_accept, this,
75 boost::asio::placeholders::error));
76 }
77 }
1 /*
2 * =====================================================================================
3 *
4 * Filename: xproxy_connection.hpp
5 *
6 * Description:
7 *
8 * Version: 1.0
9 * Created: 2009年11月26
日 15時11分04秒
10 * Revision: none
11 * Compiler: gcc
12 *
13 * Author: David Fang (A free programmer), qi_fd@163.com
14 * Company: nocompany
15 *
16 * =====================================================================================
17 */
18 #ifndef XPROXY_CONNECTION_HPP
19 #define XPROXY_CONNECTION_HPP
20
21 #include <boost/asio.hpp>
22 #include <boost/array.hpp>
23 #include <boost/noncopyable.hpp>
24 #include <boost/shared_ptr.hpp>
25 #include <boost/enable_shared_from_this.hpp>
26
27 using boost::asio::ip::tcp;
28
29 class xproxy_connection:public boost::enable_shared_from_this<xproxy_connection>,
30 private boost::noncopyable
31 {
32 public:
33 //Contruct a connection with the given io_service, the analysing server address and port
34
35 explicit xproxy_connection(boost::asio::io_service& io_service,
36 tcp::endpoint& ana_endpoint);
37
38 ~xproxy_connection();
39
40 //Start the asyncronous connection to analysing server
41
42 void start();
43
44 tcp::socket& login_clt_sock();
45
46 private:
47 //Handle completion of connection to analysing server
48
49 void handle_connect_to_ana_server(const boost::system::error_code& e);
50
51 //Handle completion of login client socket read
52
53 void handle_login_clt_sock_read(const boost::system::error_code& e,
54 std::size_t bytes_transferred);
55
56 //Handle completion of analysing server socket write
57
58 void handle_ana_srv_sock_write(const boost::system::error_code& e);
59
60 //Handle completion of analysing server socket read
61
62 void handle_ana_srv_sock_read(const boost::system::error_code& e,
63 std::size_t bytes_transferred);
64
65 //Handle completion of login client socket write
66
67 void handle_login_clt_sock_write(const boost::system::error_code& e);
68
69 //Strand to ensure the connection's handles are not called concurrently
70
71 boost::asio::io_service::strand strand_;
72
73 //analysing server endpoint
74
75 tcp::endpoint ana_endpoint_;
76
77 //socket to the flex login client
78
79 tcp::socket login_clt_sock_;
80
81 //socket to analysing server
82
83 tcp::socket ana_srv_sock_;
84
85 //buffer used to recieve data from the login client
86
87 boost::array<char, 1024> clt_buffer_;
88
89 //buffer used to recieve data from the analysing server
90
91 boost::array<char, 1024> srv_buffer_;
92 };
93
94 typedef boost::shared_ptr<xproxy_connection> xproxy_connection_ptr;
95
96 #endif
1 /*
2 * =====================================================================================
3 *
4 * Filename: xproxy_connection.cpp
5 *
6 * Description:
7 *
8 * Version: 1.0
9 * Created: 2009年11月26
日 15時12分33秒
10 * Revision: none
11 * Compiler: gcc
12 *
13 * Author: David Fang (A free programmer), qi_fd@163.com
14 * Company: nocompany
15 *
16 * =====================================================================================
17 */
18
19 #include "xproxy_connection.hpp"
20 #include <vector>
21 #include <iostream>
22 #include <boost/bind.hpp>
23
24 xproxy_connection::xproxy_connection(boost::asio::io_service& io_service,
25 tcp::endpoint& ana_endpoint)
26 :strand_(io_service),
27 ana_endpoint_(ana_endpoint),
28 login_clt_sock_(io_service),
29 ana_srv_sock_(io_service)
30 {
31 std::cout<<"new connection construct\n";
32 }
33
34 xproxy_connection::~xproxy_connection()
35 {
36 std::cout<<"connection destruct\n";
37 }
38
39 tcp::socket& xproxy_connection::login_clt_sock()
40 {
41 return login_clt_sock_;
42 }
43
44 void xproxy_connection::start()
45 {
46 std::cout<<"connection start to connect to analysing server
\n";
47 ana_srv_sock_.async_connect(ana_endpoint_,
48 strand_.wrap(boost::bind(&xproxy_connection::handle_connect_to_ana_server,
49 shared_from_this(), boost::asio::placeholders::error)));
50 }
51
52 void xproxy_connection::handle_connect_to_ana_server(const boost::system::error_code& e)
53 {
54 if(!e)
55 {
56 std::cout<<"connect to analysing server succeed,"
57 <<"now start to receive data from both sides\n";
58
59 login_clt_sock_.async_read_some(boost::asio::buffer(clt_buffer_),
60 strand_.wrap(
61 boost::bind(&xproxy_connection::handle_login_clt_sock_read,
62 shared_from_this(), boost::asio::placeholders::error,
63 boost::asio::placeholders::bytes_transferred)));
64
65 ana_srv_sock_.async_read_some(boost::asio::buffer(srv_buffer_),
66 strand_.wrap(
67 boost::bind(&xproxy_connection::handle_ana_srv_sock_read,
68 shared_from_this(), boost::asio::placeholders::error,
69 boost::asio::placeholders::bytes_transferred)));
70
71 }
72 }
73
74 void xproxy_connection::handle_login_clt_sock_read
75 (const boost::system::error_code& e, std::size_t bytes_transferred)
76 {
77 if(!e)
78 {
79 std::cout<<"data read from login client:\n";
80 std::cout.write(clt_buffer_.data(), bytes_transferred);
81 std::cout<<"\nnow send it to analysing server\n";
82 boost::asio::async_write(ana_srv_sock_,
83 boost::asio::buffer(clt_buffer_.data(), bytes_transferred),
84 strand_.wrap(boost::bind(
85 &xproxy_connection::handle_ana_srv_sock_write,
86 shared_from_this(), boost::asio::placeholders::error)));
87 }
88 else
89 {
90 std::cout<<"read data from login client error, "
91 <<"now need to shutdown this connection\n";
92 ana_srv_sock_.cancel();
93 }
94 }
95
96 void xproxy_connection::handle_ana_srv_sock_write(const boost::system::error_code& e)
97 {
98 if(!e)
99 {
100 std::cout<<"data send to analysing server complete, "
101 <<"now start to receive data from login client again\n";
102 login_clt_sock_.async_read_some(boost::asio::buffer(clt_buffer_),
103 strand_.wrap(
104 boost::bind(&xproxy_connection::handle_login_clt_sock_read,
105 shared_from_this(), boost::asio::placeholders::error,
106 boost::asio::placeholders::bytes_transferred)));
107 }
108 }
109
110 void xproxy_connection::handle_ana_srv_sock_read(
111 const boost::system::error_code& e,
112 std::size_t bytes_transferred)
113 {
114 if(!e)
115 {
116 std::cout<<"data read from analysing server:\n";
117 std::cout.write(srv_buffer_.data(), bytes_transferred);
118 std::cout<<"\nnow send it to login client\n";
119 boost::asio::async_write(login_clt_sock_,
120 boost::asio::buffer(srv_buffer_.data(), bytes_transferred),
121 strand_.wrap(
122 boost::bind(&xproxy_connection::handle_login_clt_sock_write,
123 shared_from_this(), boost::asio::placeholders::error)));
124 }
125 else
126 {
127 std::cout<<"read data from analysing server error, "
128 <<"now need to shutdown this connection\n";
129 login_clt_sock_.cancel();
130 }
131 }
132
133 void xproxy_connection::handle_login_clt_sock_write(const boost::system::error_code& e)
134 {
135 if(!e)
136 {
137 std::cout<<"data send to login client complete, "
138 <<"now start to receive data from analysing server again\n";
139 ana_srv_sock_.async_read_some(boost::asio::buffer(srv_buffer_),
140 strand_.wrap(
141 boost::bind(&xproxy_connection::handle_ana_srv_sock_read,
142 shared_from_this(), boost::asio::placeholders::error,
143 boost::asio::placeholders::bytes_transferred)));
144 }
145 }
1 BOOST_INC=/home/done/dev_lib/boost_1_38_0/
2 BOOST_LIB=/home/done/dev_lib/boostlibs/
3 LIB_THREAD=$(BOOST_LIB)libboost_thread-gcc42-mt-s-1_38.a
4 LIB_SYSTEM=$(BOOST_LIB)libboost_system-gcc42-mt-s-1_38.a
5 SYS_INC=/usr/include/
6 CPP_INC=/usr/include/c++/4.2/
7 default:xproxy_main.o xproxy_server.o xproxy_connection.o
8 g++ -o xproxy xproxy_main.o xproxy_server.o xproxy_connection.o $(LIB_THREAD) $(LIB_SYSTEM) -lpthread
9 xproxy_main.o:xproxy_main.cpp xproxy_server.hpp
10 g++ -c -I$(SYS_INC) -I$(BOOST_INC) -I$(CPP_INC) xproxy_main.cpp
11 xproxy_server.o:xproxy_server.cpp xproxy_connection.hpp
12 g++ -c -I$(SYS_INC) -I$(BOOST_INC) -I$(CPP_INC) xproxy_server.cpp
13 xproxy_connection.o:xproxy_connection.cpp xproxy_connection.hpp
14 g++ -c -I$(SYS_INC) -I$(BOOST_INC) -I$(CPP_INC) xproxy_connection.cpp
15 clean:
16 rm *.o xproxy 2>/dev/null