Re: Please Help!!! - CAsyncSocket::OnReceive Not Working for Microsoft UDP Application (msocudp)

Roshan <>
Tue, 20 May 2008 14:58:24 -0700 (PDT)
On May 20, 12:31 pm, "Scott McPhillips [MVP]" <org-dot-mvps-at-
scottmcp> wrote:

"Roshan" <> wrote in message

The result I am currently getting from running my code is that: I am
sending the packet and 10 result packets are being sent back, but
OnReceive is not getting invoked at all which leads to my program
hanging at the WaitForSingleObject() calls.

I pointed out serious design errors in your code. You did not address o=


correct any of them. OnReceive will not be invoked until you do correct=


Scott McPhillips [VC++ MVP]


I have created a CWinThread derived class. I have been trying to
follow some examples from the web.
I am trying to pass the socket from my dialog class to my thread
class. One problem I am having now when running the code is that it is
failing when I am attaching the socket handle to the socket object in
the InitInstance() function of my thread class.
The error I'm getting is access violation. Others seemed to have
gotten this error before. How do you fix this?

Code Snippets:

CProdTestUdpThread (My CWinThread derived class)

BOOL CProdTestUdpThread::InitInstance()
    // TODO: perform and per-thread initialization here
    m_UDPSocket.Attach(m_hSocket); (*** THIS IS WHERE THE ERROR

    m_UDPSocket.m_nBytesSent = 0;
    m_UDPSocket.m_sendBuffer = m_sendString;
    m_UDPSocket.m_nBytesBufferSize = m_sendString.GetLength() + 1;



    WaitForSingleObject(m_hRcvEvent, INFINITE);


    return TRUE;

CProdTestDlg (Normal Function definition in my dialog source file --

void CProdTestDlg::NormalFunction(int hexNum)
    CString sendString, verString = "01", seqString, twoByteHexAddInfo;
    m_cmdString = "02";

    twoByteHexAddInfo.Format("%04x", hexNum);
    seqString.Format("%02x", m_pUDPSocket->m_sequenceNumber);
    sendString = verString + seqString + m_cmdString + twoByteHexAddInfo;

    CProdTestUdpThread *pThread =
        (CProdTestUdpThread *) AfxBeginThread(

    // Pass the socket to the thread by passing the socket handle.
    // You cannot pass a CSocket object across threads.
    pThread->m_hSocket = m_pUDPSocket->Detach();
    pThread->m_sendString = sendString;
    pThread->m_delay = 10;
    m_pUDPSocket->m_pRcvEvent = &(pThread->m_hRcvEvent);

                // Now start the thread.

    WaitForSingleObject(pThread->m_hThread, INFINITE);

MICROSOFT's UDP OnReceive() Function (Instead of the class being
named, CUdpAsySk, I changed it to CProdTestUdpSk).

void CProdTestUdpSk::OnReceive(int nErrorCode)

    SetEvent(*m_pRcvEvent); // *** NOTIFY THREAD CLASS WHEN ALL 10
                                                            // PACKETS


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