CSocket: Connect returned WSAEISCONN

From:
yschan2008@gmail.com
Newsgroups:
microsoft.public.vc.mfc
Date:
Wed, 8 Oct 2008 01:15:15 -0700 (PDT)
Message-ID:
<71857a79-8ff3-429b-936d-e22c995c6053@r15g2000prh.googlegroups.com>
Hi,

I' ve written this client program using MFC's CSocket. It worked fine
and able to connect a server program. Both my client and server
programs are residing in different PC. Then, came the issue when my
server's PC shutdown abruptly (means the server program did not
shutdown properly). When the server's PC is down, my client will try
to establish the TCP connection with the server program (as shown in
the code below marked ==Original Code==). Then, the server PC is
started up and my server program start to run. From the TCPView tool,
I can see the client program established the connection to the server
program for awhile and then immediately the connection was lost in the
TCPView. From my logged file is showing the winsock error:WSAEISCONN.
And alsomy code will loop continuously and the connect always returned
WSAEISCONN. Furthermore, in the TCPView I don't see any connection was
established for the socket.

Then I tried out the modified code as shown below marked with
==Modified Code =====. It seem to be working when I simulated the
scenario I described previously.

So, my question is why my original code is giving the WSAEISCONN while
I don't see any connection in the TCPView? While the modified codes
worked. Both seems looked the same to me except I created new socket
for each attempt in the modified code.

Hopefully someone can provide me some guidance and explanation. Thank
you.

=========================================
=========Original Code ======================

        //CSimpleSocket is derived from CSocket
        m_pSocket = new CSimpleSocket(this);

        if (!m_pSocket)
        {
            return ERR_MEM;
        }

        // create the Windows socket and attach it, will also bind the
socket to the specified address
        if (!m_pSocket->Create())
        {
            return ERR_SOCK_CREATE;
        }

        while (TRUE)
        {
            if (!m_pSocket->Connect(m_strPassiveIP, m_wPassiveTCP))
            {
                int nWin32ErrorCode = GetLastError();
                // will logg the nWin32ErrorCode value and proceed to try again
            }
            else
            {
                //successfully connect.
                break;
            }
            Sleep(5000); // will try again after 5 secs

        }

=========================================
=========Modified Code ======================
        while (TRUE)
        {

                //CSimpleSocket is derived from CSocket
      m_pSocket = new CSimpleSocket(this);

               if (!m_pSocket)
               {
                   return ERR_MEM;
                }

                // create the Windows socket and attach it, will also bind
the socket to the specified address
                if (!m_pSocket->Create())
                {
                    return ERR_SOCK_CREATE;
                }

            if (!m_pSocket->Connect(m_strPassiveIP, m_wPassiveTCP))
            {
                int nWin32ErrorCode = GetLastError();
                // will logg the nWin32ErrorCode value and proceed to try again
            }
            else
            {
                //successfully connect.
                break;
            }

      delete m_pSocket;
      m_pSocket = Null;

            Sleep(5000); // will try again after 5 secs

        }

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