1 拒絕連接
什麼都不做，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 接受新連接
在 1079 端口偵聽新連接，接受連接之後什麼都不做，程序空等。muduo 會自動丟棄收到的數據。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 主動斷開連接
接受新連接之後主動斷開。finger03.cc
以下省略頭文件和 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 讀取用戶名，然後斷開連接
如果讀到一行以
結尾的消息，就斷開連接。finger04.cc
注意這段代碼有安全問題，如果惡意客戶端不斷發送數據而不換行，會撐爆服務端的內存。另外，Buffer::findCRLF() 是線性查找，如果客戶端每次發一個字節，服務端的時間復雜度為 O(N^2)，會消耗 CPU 資源。
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. 讀取用戶名、輸出錯誤信息、然後斷開連接
如果讀到一行以
結尾的消息，就發送一條出錯信息，然後斷開連接。finger05.cc
安全問題同上。
1: void onMessage(const TcpConnectionPtr& conn, 2: Buffer* buf, 3: Timestamp receiveTime) 4: { 5: if (buf->findCRLF()) 6: { 7: conn->send("No such user
"); 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. 從空的 UserMap 裡查找用戶
從一行消息中拿到用戶名（第 22 行），在 UserMap 裡查找，然後返回結果。finger06.cc
安全問題同上。
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) + "
"); 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 裡添加一個用戶
與前面幾乎完全一樣，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) + "
"); 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: }
以上就是全部內容，可以用 telnet 扮演客戶端來測試我們的簡單 finger 服務端。
Telnet 測試
在一個命令行窗口運行
$ ./bin/twisted_finger07
另一個命令行運行
$ 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.
再試一次
$ 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.
