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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 <muduo/net/EventLoop.h>
   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 <muduo/net/EventLoop.h>
   2: #include <muduo/net/TcpServer.h>
   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<string, string> 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<string, string> 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)

posted on 2011-02-23 21:34 陈硕 阅读(...) 评论(...) 编辑 收藏

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