VC: use Windows Socket to develop applications

Socket programming based on TCP (connection oriented)

I. Client:

1. Open a Socket );

2. Initiate a connection request );

3. If the connection is successful, data will be exchanged (read, write, send, and recv );

4. Data Exchange is complete. close the connection (shutdown or close );

Ii. server side:

1. Open a Socket );

2. bind the socket to the server address (bind );

3. Specify the socket as the server socket (listen) and prepare the connection request;

4. Waiting for connection requests (connect );

5. If the connection request arrives, the connection is established for data exchange (read, write, send, and recv );

6. Data Exchange is complete. close the connection (shutdown or close );

 

UDP-based Socket programming

1. Client/Server:

1. Open a Socket );

2. bind the socket to the specified server address and port (bind );

3. Data Exchange (read, write, send, and recv );

4. Data Exchange is complete. close the connection (shutdown or close );

 

Iii. MFC support for Socket:

1. Create a CAsyncSocket object;

2. send and receive data packets (SendTo and RecvFrom );

3. Connect to the server );

4. Receive connections (Listen );

5. Send and Receive streaming data (Send and Receive );

6. Close the socket );

7. GetLastError ).

 

Iv. instances: online chat tools

 

 

Client:

 

 

1 ,....

2. Use the Class Wizard to overload the CAsyncSocket class and generate a new MySocket class ..

3. Use the Class Wizard to reload the OnReceive (int nErrorCode), OnSend (int nErrorCode), and OnConnect (int nErrorCode) functions of CAsyncSocket.

Void MySocket: OnReceive (int nErrorCode)

{

// TODO: Add your specialized code here and/or call the base class

// Get the pointer of the dialog box

CTestApp * pApp = (CTestApp *) AfxGetApp ();

CTestDlg * pDlg = (CTestDlg *) pApp-> m_pMainWnd;

// Insert a message to the edit box

Char * pbuf = new char [4096];

Int ibufsize = 4096;

Int ircvd;

CString strrecvd;

Ircvd = Receive (pbuf, ibufsize );

If (ircvd = SOCKET_ERROR)

{

PDlg-> MessageBox ("SOCKET_ERROR ");

}

Else

{

Pbuf [ircvd] = NULL;

PDlg-> m_recmsg + = "server :";

PDlg-> m_recmsg + = pbuf;

PDlg-> m_recmsg + = "\ r \ n ";

PDlg-> RefreshScreen ();

}

Delete pbuf;

CAsyncSocket: OnReceive (nErrorCode );

}

 

Void MySocket: OnSend (int nErrorCode)

{

// TODO: Add your specialized code here and/or call the base class

CAsyncSocket: OnSend (nErrorCode );

}

 

Void MySocket: OnConnect (int nErrorCode)

{

// TODO: Add your specialized code here and/or call the base class

CTestApp * pApp = (CTestApp *) AfxGetApp ();

CTestDlg * pDlg = (CTestDlg *) pApp-> m_pMainWnd;

 

Int iResult = nErrorCode;

CString buffer;

 

Int namelen;

If (iResult! = 0)

{

Buffer. Format ("failed to connect to the server. \ R \ n ");

PDlg-> m_recmsg + = buffer;

}

Else

{

Namelen = sizeof (sockaddr_in );

Buffer. Format ("successfully connected to the server % s: % d. \ r \ n", pDlg-> m_ipstr, pDlg-> m_port );

PDlg-> m_recmsg + = buffer;

PDlg-> GetDlgItem (IDC_SEND)-> EnableWindow (TRUE );

PDlg-> GetDlgItem (IDOK)-> EnableWindow (TRUE );

}

PDlg-> RefreshScreen ();

CAsyncSocket: OnConnect (nErrorCode );

}

4. In the C * Dlg class

Header file:

# Include "MySocket. h"

 

MySocket m_socket;

CString m_ipstr;

 

 

In the. CPP file:

 

Void CTestDlg: OnSend ()

{

// TODO: Add your control notification handler code here

Int ilen;

Int isent;

UpdateData (TRUE );

If (m_msg! = "")

{

Ilen = m_msg.GetLength ();

 

Isent = m_socket.Send (LPCTSTR (m_msg), ilen );

If (isent = SOCKET_ERROR)

{

MessageBox ("connection failed. Please try again! ");

// Connect = false;

}

Else

{

M_recmsg + = "client:" + m_msg;

M_recmsg + = "\ r \ n ";

UpdateData (FALSE );

}

}

}

Void CTestDlg: RefreshScreen ()

{

UpdateData (false );

}

Void CTestDlg: OnConnect ()

{

If (! AfxSocketInit ())

{

AfxMessageBox ("IDP_SOCKETS_INIT_FAILED ");

Return;

}

GetDlgItemText (IDC_IPADDRESS1, m_ipstr );

M_socket.m_hSocket = INVALID_SOCKET;

UpdateData (true );

 

BOOL flag = m_socket.Create ();

If (! Flag)

{

AfxMessageBox ("socket error ");

Return;

}

M_socket.Connect (m_ipstr, m_port );

}

 

Void CTestDlg: OnOK ()

{

// TODO: Add extra validation here

M_socket.Close ();

CDialog: OnOK ();

}

 

 

Server:

 

 

1 ,....

2. Use the Class Wizard to overload the CAsyncSocket class and generate a new MySocket class ..

3. Use the Class Wizard to reload the OnReceive (int nErrorCode) and OnSend (int nErrorCode) functions of CAsyncSocket.

 

Void MySocket: OnReceive (int nErrorCode)

{

// TODO: Add your specialized code here and/or call the base class

CTestApp * pApp = (CTestApp *) AfxGetApp ();

CTestDlg * pDlg = (CTestDlg *) pApp-> m_pMainWnd;

// Insert a message to the list box

Char * pbuf = new char [4096];

Int ibufsize = 4096;

Int ircvd;

CString strrecvd;

Ircvd = Receive (pbuf, ibufsize );

If (ircvd = SOCKET_ERROR)

{

PDlg-> MessageBox ("SOCKET_ERROR ");

}

Else

{

Pbuf [ircvd] = NULL;

PDlg-> m_msg + = "client :";

PDlg-> m_msg + = pbuf;

PDlg-> m_msg + = "\ r \ n ";

PDlg-> RefreshScreen ();

}

Delete pbuf;

CAsyncSocket: OnReceive (nErrorCode );

}

 

Void MySocket: OnSend (int nErrorCode)

{

// TODO: Add your specialized code here and/or call the base class

CAsyncSocket: OnSend (nErrorCode );

}

 

 

4. Create a New MyServerSocket class and add MySocket * m_socket; that is, the socket pointer after receiving the request.

 

MySocket * m_socket;

 

Void CMyServerSocket: OnAccept (int nErrorCode)

{

// TODO: Add your specialized code here and/or call the base class

CTestApp * pApp = (CTestApp *) AfxGetApp ();

CTestDlg * pDlg = (CTestDlg *) pApp-> m_pMainWnd;

// Display the connection message

PDlg-> m_msg = "connecting the client to the server ";

PDlg-> m_msg + = "\ r \ n ";

PDlg-> RefreshScreen ();

PDlg-> GetDlgItem (IDC_SEND)-> EnableWindow (TRUE );

PDlg-> GetDlgItem (IDOK)-> EnableWindow (TRUE );

 

MySocket * psocket = new MySocket ();

If (Accept (* psocket ))

{

Psocket-> AsyncSelect (FD_READ );

M_socket = psocket;

}

Else

{

Delete psocket;

}

CAsyncSocket: OnAccept (nErrorCode );

}

5. C * Dlg class

 

Void CTestDlg: RefreshScreen ()

{

UpdateData (false );

}

Void CTestDlg: OnListen () // create a server

{

// TODO: Add your control notification handler code here

UpdateData (true );

If (! AfxSocketInit ())

{

AfxMessageBox ("IDP_SOCKETS_INIT_FAILED ");

Return;

}

BOOL flag = m_serversocket.Create (m_port );

If (! Flag)

{

AfxMessageBox ("socket error ");

Return;

}

Flag = m_serversocket.Listen (1 );

If (! Flag)

{

AfxMessageBox ("socket error ");

Return;

}

SetDlgItemText (IDC_LISTEN, "listening ");

}

 

Void CTestDlg: OnSend ()

{

// TODO: Add your control notification handler code here

Int ilen;

Int isent;

UpdateData (TRUE );

If (m_sendmsg! = "")

{

Ilen = m_sendmsg.GetLength ();

 

Isent = m_serversocket.m_socket-> Send (LPCTSTR (m_sendmsg), ilen );

If (isent = SOCKET_ERROR)

{

MessageBox ("connection failed. Please try again! ");

}

Else

{

M_msg + = "server:" + m_sendmsg;

M_msg + = "\ r \ n ";

UpdateData (FALSE );

}

}

}

 

 

Void CTestDlg: OnOK ()

{

// TODO: Add extra validation here

M_sendmsg = "server logout ";

UpdateData (false );

OnSend ();

M_serversocket.Close ();

CDialog: OnOK ();

}