Basic Socket Programming

License: None.

Brief Description:
This is another program I made when I was begining to learn MFC. This program Illustrates the simple usage of the CAsyncSocket class provided by MFC, which is useful for socket programming. The program will connect two PC in a network and enables chating by the two PC.

The CAsyncSocket class is a wrapper class for the asynchronous Winsock calls. It has a number of useful functions that facilitate using the Winsock API. Here I list Some of them:

1. Accept :Handles an incoming connection on a listening socket, filling a new socket with the address information.
2. Close :Closes the socket.
3. Connect :Connects the socket to a remote address and port.
4. Create :Completes the initialization process begun by the constructor.
5. Listen :Instructs a socket to watch for incoming connections.
6. OnAccept :Handles the Windows message generated when a socket has an incoming connection to accept (often overridden by derived classes).
7. OnClose :Handles the Windows message generated when a socket closes (often overridden by derived classes).
8. OnConnect :Handles the Windows message generated when a socket becomes connected or a connection attempt ends in failure (often overridden by derived classes).
9. OnReceive :Handles the Windows message generated when a socket has data that can be read with Receive() (often overridden by derived classes).
10. OnSend :Handles the Windows message generated when a socket is ready to accept data that can be sent with Send() (often overridden by derived classes).
11. Receive :Reads data from the remote socket to which this socket is connected.
12. Send :Sends data to the remote socket to which this socket is connected.

There are more function from this class, but I just listed functions used in this program.

The Code:

First, look at the MySocket class which is derived from the CAsyncSocket class and overides some of the function, which are:


each of these function check if an errors occured, and call the appropriate function in the dialog class 'CSockDlg'. This CSockDlg is where most of the dialog message handling is done.


These two will represent the connecting socket and the listening socket.
And those two will be created and connected to the specified port and host address. The code below show how to create ,Listen and connect the sockets class. To connect, both the hostName and the port need to be given and the listening socket only needs the port number to listen.
Make sure that only one socket listen to a port at a time, which mean two sockets can't litsen to a port at the same time.


The Accept used by the listening socket to accept a new connection from another socket.


Now the sockets are ready for sending and receiving data to each other.


Finally, when the application exit, we need to close the sockets.



This program has been tested in a LAN network with Win98 and Win2K. I'm not sure if it runs ok in Windows XP.

Enjoy.
Regards.

Attached Files

Sock.zip (71.4 KB, 1308 views)

__________________
When you say "I wrote a program that crashed Windows," people just stare at you blankly and say "Hey, I got those with the system, for free." Linus Torvalds

hi,
i am in very beginning state of winsock programming
your article is very useful for me
and i want to know how to program if the server socket has to accept more than one connection request at the same port number
pl. help me
awaiting for ur reply


regards
gowri