Socket programming in MFC is usually a bit messy. It's always
clean and convenient to write the socket programs using Win32.
A
big advantage writing these programs in Win32 is, we can
follow the same model as in any Unix C++ socket program. Also,
with each and every new version of Winsock, we don't know how
many bugs are going to get added to the development
frameworks.
Anyway,
now let's get down to business. This article does not try to
cover all the minute details of winsock client programming,
but for the basics. The relevant steps for creating a
synchronous client socket are:
- Create
a socket and get the handle
- Populate
the SOCKADDR_IN structure with the Server IP and Port
Number
- Connect
using the connect function
- Send
and Recv using the socket
- Shutdown
and Close when all jobs are done
The
following sample illustrates the above steps. Only one item
missed out here is the usage of recv function.
#include
<winsock2.h>
#include <iostream.h>
int gPort = 8780;
void main()
{
SOCKET lhSocket;
SOCKADDR_IN lSockAddr;
WSADATA wsaData;
int lConnect;
int
lLength;
char lData[]="SendData";
if(WSAStartup(MAKEWORD(2,0),&wsaData)
!= 0)
{
cout<<"Socket Initialization Error. Program
aborted\n";
return;
}
lhSocket =
socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(lhSocket ==
INVALID_SOCKET)
{
cout<<"Invalid Socket
"<<GetLastError()<<". Program
Aborted\n"<<endl;
}
memset(&lSockAddr,0,
sizeof(lSockAddr));
lSockAddr.sin_family =
AF_INET;
lSockAddr.sin_port =
htons(gPort);
lSockAddr.sin_addr.s_addr
= inet_addr("IPAddress");
lConnect =
connect(lhSocket,(SOCKADDR *)&lSockAddr,sizeof(SOCKADDR_IN));
if(lConnect != 0)
{
cout<<"Connect Error. Program aborted\n";
return;
}
lLength =
send(lhSocket,lData,strlen(lData),0);
if(lLength <
strlen(lData))
{
cout<<"Send Error.\n";
}
closesocket(lhSocket);
return;
}
Note:
The socket programs in MFC need the library ws2_32.lib to be
referenced before linking. Otherwise the VC++ linker throws
errors.