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This article presents a fully functional implementation of a FTP server. It can handle multiple connections at the same time (multi threaded) and has most of the features you would find in other commercial/shareware FTP servers. The server handles all basic FTP commands and offers easy user account management.
This article describes the most important classes of the application:
This class is in fact the FTP server, and controls all other classes needed for the server to work. Although
CFTPServer is part of a dialog based application, it does not rely on a User Interface and can easily be implemented in a service or console application as well.
Activates the FTP server. It opens a listening socket (port 21) to accept connections.
Deactivates the server and disconnects all connected clients by terminating the running threads.
Is FTP server active?
void SetMaxUsers(int nValue)
Set maximum number of users.
void SetPort(int nValue)
Set listening port for new connections.
void SetTimeout(int nValue)
Set connection timeout (in ms). When a client does not send any commands for
nValue ms, the server will close the connection.
void SetWelcomeMessage(LPCTSTR lpszText)
Set the text that will be displayed when the client logs on.
void Initialize(CFTPEventSink *pEventSink)
Set the event sink. The event sink will be the window (or any class) that receives the events generated by the FTP server. See
CFTPEventSink description for more info.
To be able to 'send' events from the
CFTPServer class to the main application, I used multiple inheritance and virtual functions. The
CFTPEventSink is just a helper class that contains nothing else than virtual functions, when you derive your class from
CFTPEventSink these virtual functions become a kind of events. The class
CFTPServer has a reference to this class and calls the virtual functions when it needs to notify the application.
The following 'events' are available:
void OnFTPUserConnected(DWORD nThreadID, LPCTSTR lpszUser, LPCSTR lpszAddress);
A client has successfully connected.
void OnFTPUserDisconnected(DWORD nThreadID, LPCTSTR lpszUser);
A client has disconnected.
void OnFTPStatusChange(int nType, LPCTSTR lpszText);
FTP server status has changed (file downloaded/uploaded).
void OnFTPReceivedBytesChange(int nBytes);
The number of received bytes has changed.
void OnFTPSentBytesChange(int nBytes);
The number of sent bytes received has changed.
void OnFTPStatisticChange(int nType, int nValue);
A statistic has changed, for example the number of downloaded or uploaded files.
Other helper classes:
CUserManager handles all user and file related stuff. It checks the connected users for their access rights and converts remote to local paths.
CUserManager uses serializing for storing and loading the user settings.
This socket is part of
CFTPServer and accepts incoming connections. When a clients connects to the server,
CListenSocket accepts the connection and creates a new thread (
CConnectThread) that will take care of all further communication between the client and the server. After the thread has been created,
CListenSocket will return to its waiting state.
This thread will handle all communication between the client and the server using
This socket class will process all incoming FTP commands and send back the response to the client.
When data needs to be send or received, a
CDataSocket will be created by
CDataSocket class will transfer this data (such as directory listings and files) on a separate port.
All the other classes are just UI related and are only included to make it look a little bit fancier.
To use the class in your application, you need to do the following:
- Add the class to your application.
- Derive your main class from
- Override the virtual functions of
CFTPEventSink; these are the events that come from the server.
- Initialize the eventsink.
- Start the server.
class CMyDlg : public CDialog, CFTPEventSink
virtual void OnFTPUserConnected(DWORD nThreadID,
LPCTSTR lpszUser, LPCSTR lpszAddress);
virtual void OnFTPUserDisconnected(DWORD nThreadID, LPCTSTR lpszUser);
virtual void OnFTPStatusChange(int nType, LPCTSTR lpszText);
virtual void OnFTPReceivedBytesChange(int nBytes);
virtual void OnFTPSentBytesChange(int nBytes);
virtual void OnFTPStatisticChange(int nType, int nValue);
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Inspired by FileZilla Server.