Muduo 网络编程示例之四：Twisted Finger

陈硕 (giantchen_AT_gmail)

Blog.csdn.net/Solstice

这是《Muduo 网络编程示例》系列的第四篇文章。

Muduo 全系列文章列表： http://blog.csdn.net/Solstice/category/779646.aspx

Python Twisted 是一款非常好的网络库，它也采用 Reactor 作为网络编程的基本模型，所以从使用上与 muduo 颇有相似之处。（当然，muduo 没有 deferreds）Finger 是 twisted 文档的一个经典例子，本文展示如何用 muduo 来实现最简单的 finger 服务端。限于篇幅，只实现 finger01~07。代码位于 examples/twisted/finger 。

1 拒绝连接

什么都不做，程序空等。finger01.cc

1: #include

2:

3: using namespace muduo;

4: using namespace muduo::net;

5:

6: int main()

7: {

8:   EventLoop loop;

9:   loop.loop();

10: }

2 接受新连接

在 1079 端口侦听新连接，接受连接之后什么都不做，程序空等。muduo 会自动丢弃收到的数据。finger02.cc

1: #include

2: #include

3:

4: using namespace muduo;

5: using namespace muduo::net;

6:

7: int main()

8: {

9:   EventLoop loop;

10:   TcpServer server(&loop, InetAddress(1079), "Finger");

11:   server.start();

12:   loop.loop();

13: }

3 主动断开连接

接受新连接之后主动断开。finger03.cc

以下省略头文件和 namespace。

1: void onConnection(const TcpConnectionPtr& conn)

2: {

3: if (conn->connected())

4:   {

5:   conn->shutdown();

6: }

7: }

8:

9: int main()

10: {

11:   EventLoop loop;

12:   TcpServer server(&loop, InetAddress(1079), "Finger");

13:   server.setConnectionCallback(onConnection);

14:   server.start();

15:   loop.loop();

16: }

4 读取用户名，然后断开连接

如果读到一行以 /r/n 结尾的消息，就断开连接。finger04.cc

注意这段代码有安全问题，如果恶意客户端不断发送数据而不换行，会撑爆服务端的内存。另外，Buffer::findCRLF() 是线性查找，如果客户端每次发一个字节，服务端的时间复杂度为 O(N^2)，会消耗 CPU 资源。

1: void onMessage(const TcpConnectionPtr& conn,

2:              Buffer* buf,

3:              Timestamp receiveTime)

4: {

5: if (buf->findCRLF())

6: {

7:     conn->shutdown();

8: }

9: }

10:

11: int main()

12: {

13:   EventLoop loop;

14:   TcpServer server(&loop, InetAddress(1079), "Finger");

15:   server.setMessageCallback(onMessage);

16:   server.start();

17:   loop.loop();

18: }

5. 读取用户名、输出错误信息、然后断开连接

如果读到一行以 /r/n 结尾的消息，就发送一条出错信息，然后断开连接。finger05.cc

安全问题同上。

1: void onMessage(const TcpConnectionPtr& conn,

2:              Buffer* buf,

3:              Timestamp receiveTime)

4: {

5: if (buf->findCRLF())

6: {

7:     conn->send("No such user/r/n");

8:   conn->shutdown();

9:   }

10: }

11:

12: int main()

13: {

14:   EventLoop loop;

15:   TcpServer server(&loop, InetAddress(1079), "Finger");

16:   server.setMessageCallback(onMessage);

17:   server.start();

18:   loop.loop();

19: }

6. 从空的 UserMap 里查找用户

从一行消息中拿到用户名（第 22 行），在 UserMap 里查找，然后返回结果。finger06.cc

安全问题同上。

1: typedef std::map UserMap;

2: UserMap users;

3:

4: string getUser(const string& user)

5: {

6: string result = "No such user";

7:   UserMap::iterator it = users.find(user);

8: if (it != users.end())

9:   {

10:   result = it->second;

11: }

12:   return result;

13: }

14:

15: void onMessage(const TcpConnectionPtr& conn,

16:                Buffer* buf,

17:                Timestamp receiveTime)

18: {

19:   const char* crlf = buf->findCRLF();

20:   if (crlf)

21:   {

22:     string user(buf->peek(), crlf);

23:     conn->send(getUser(user) + "/r/n");

24:     buf->retrieveUntil(crlf + 2);

25:     conn->shutdown();

26:   }

27: }

28:

29: int main()

30: {

31:   EventLoop loop;

32:   TcpServer server(&loop, InetAddress(1079), "Finger");

33:   server.setMessageCallback(onMessage);

34:   server.start();

35:   loop.loop();

36: }

7. 往 UserMap 里添加一个用户

与前面几乎完全一样，只多了第 31 行。finger07.cc

1: typedef std::map UserMap;

2: UserMap users;

3:

4: string getUser(const string& user)

5: {

6: string result = "No such user";

7:   UserMap::iterator it = users.find(user);

8: if (it != users.end())

9:   {

10:   result = it->second;

11: }

12:   return result;

13: }

14:

15: void onMessage(const TcpConnectionPtr& conn,

16:                Buffer* buf,

17:                Timestamp receiveTime)

18: {

19:   const char* crlf = buf->findCRLF();

20:   if (crlf)

21:   {

22:     string user(buf->peek(), crlf);

23:     conn->send(getUser(user) + "/r/n");

24:     buf->retrieveUntil(crlf + 2);

25:     conn->shutdown();

26:   }

27: }

28:

29: int main()

30: {

31:   users["schen"] = "Happy and well";

32:   EventLoop loop;

33:   TcpServer server(&loop, InetAddress(1079), "Finger");

34:   server.setMessageCallback(onMessage);

35:   server.start();

36:   loop.loop();

37: }

以上就是全部内容，可以用 telnet 扮演客户端来测试我们的简单 finger 服务端。

Telnet 测试

在一个命令行窗口运行

$ ./bin/twisted_finger07

另一个命令行运行

$ telnet localhost 1079

Trying ::1...

Trying 127.0.0.1...

Connected to localhost.

Escape character is '^]'.

muduo

No such user

Connection closed by foreign host.

再试一次

$ telnet localhost 1079

Trying ::1...

Trying 127.0.0.1...

Connected to localhost.

Escape character is '^]'.

schen

Happy and well

Connection closed by foreign host.


冒烟测试过关。

(待续)