VC FTP服务器程序分析（三）

 1 void CControlSocket::OnReceive(int nErrorCode) 
 2 {
 3     try
 4     {
 5         TCHAR buff[BUFFER_SIZE+1];
 6 
 7         int nRead = Receive(buff, BUFFER_SIZE);
 8         switch (nRead)
 9         {
10             case 0:
11                 Close();
12                 break;
13 
14             case SOCKET_ERROR:
15                 if (GetLastError() != WSAEWOULDBLOCK) 
16                 {
17                     TCHAR szError[256];
18                     wsprintf(szError, "OnReceive error: %d", GetLastError());
19                     AfxMessageBox (szError);
20                 }
21                 break;
22 
23             default:
24                 if ((m_RxBuffer.GetLength() + nRead) > BUFFER_OVERFLOW)
25                 {
26                     ((CClientThread *)m_pThread)->PostStatusMessage("Buffer overflow: DOS attack?");
27 
28                     // buffer overflow (DOS attack ?)
29                     AfxGetThread()->PostThreadMessage(WM_QUIT,0,0);
30                 }
31                 else
32                 if (nRead != SOCKET_ERROR && nRead != 0)
33                 {
34                     // terminate the string
35                     buff[nRead] = 0; 
36                     m_RxBuffer += CString(buff);
37 
38                     GetCommandLine();
39                 }    
40                 break;
41         }
42     }
43     catch(...)
44     {
45         // something bad happened... (DOS attack?)
46         ((CClientThread *)m_pThread)->PostStatusMessage("Exception occurred in CSocket::OnReceive()!");
47         // close the connection.
48         AfxGetThread()->PostThreadMessage(WM_QUIT,0,0);
49     }
50     CSocket::OnReceive(nErrorCode);
51 }

 1 void CControlSocket::GetCommandLine()
 2 {
 3     CString strTemp;
 4     int nIndex;
 5 
 6     while(!m_RxBuffer.IsEmpty())                //有接收到的数据待处理
 7     {
 8         nIndex = m_RxBuffer.Find("\r\n");       //找一条完整的命令的结束符
 9         if (nIndex != -1)
10         {
11             strTemp = m_RxBuffer.Left(nIndex);  //将这条命令提取出来
12             m_RxBuffer = m_RxBuffer.Mid(nIndex + 2); //更新m_RxBuffer 去掉已经提取出来的命令
13             if (!strTemp.IsEmpty())
14             {
15                 m_strCommands.AddTail(strTemp); //可能while循环中提取出多条命令，这里增加一个队列
16                 // parse and execute command
17                 ProcessCommand();               //去处理这些命令,如果直接处理命令的话，就没有上面m_strCommandsz这个队列缓冲了
18             }
19         }
20         else
21             break;
22     }
23 }