Node.js to c++ client: not receiving message from socket.emit

Question

I'm trying to communicate between a c++ client and a node.js server. I can send data to the server, but I'm unable to send any messages back to the client. My simple understanding of socket.emit is that it should send a message that's retrievable by calling recv() on the FD_READ message in a basic windows message loop. I might be missing something there.

Here's the relevant client code:

s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (s == INVALID_SOCKET)
{
    MessageBox(hwnd, TEXT("3"), TEXT(""), MB_OK | MB_ICONEXCLAMATION);
    return 0;
}

long hostname = inet_addr("192.168.1.70");
target.sin_family = AF_INET;
target.sin_port = htons(server_port_num);
target.sin_addr.s_addr = hostname;

if (connect(s, (SOCKADDR *)&target, sizeof(target)) == SOCKET_ERROR)
{
    MessageBox(hwnd, TEXT("999"), TEXT(""), MB_OK | MB_ICONEXCLAMATION);
    return 0;
}

WSAAsyncSelect(s, hwnd, CUST_MSG, FD_READ | FD_CONNECT | FD_CLOSE);

I send data, which is received and output on the server console:

int nret = send(s, buffer, strlen(buffer), 0);

Then I attempt to send some data back in the same server event that receives the data:

this.socket.on('data', function (buffer) {
    try {
        logger.warn(buffer + "\n");
        socket.emit('message', 'psst, wanna buy some macaroni?');
        //that.messageHandler(that, buffer);
    } catch (err) {
        logger.warn('Protocol ' + err + ' ' + that.socket.remoteAddress);
        that.dispose();
    }
});

I have a message loop, but it doesn't detect a message sent from socket.emit():

MSG msg;
while (GetMessage(&msg, NULL, 0, 0) > 0)
{
    if (numBytes > 0) {
        wchar_t buffer[256];
        wsprintfW(buffer, L"%d", numBytes);
        MessageBox(hwnd, buffer, TEXT(""), MB_OK | MB_ICONEXCLAMATION);
    }

    TranslateMessage(&msg);
    DispatchMessage(&msg);

}

//MESSAGE LOOP FUNCTION:
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) //handle the messages
{
case CUST_MSG: //Is a message being sent?
{
    switch (lParam) //If so, which one is it?
    {
    case FD_ACCEPT:
        MessageBox(hwnd, TEXT("accept"), TEXT(""), MB_OK | MB_ICONEXCLAMATION);
        accept(wParam, NULL, NULL);
        break;
    case FD_CONNECT:
        MessageBox(hwnd, TEXT("connect"), TEXT(""), MB_OK | MB_ICONEXCLAMATION);
        break;
    case FD_READ:
        char buffer[80];
        int byte_num;
        memset(buffer, 0, sizeof(buffer));
        byte_num = recv(wParam, buffer, sizeof(buffer) - 1, 0);
        MessageBox(hwnd, TEXT("READING"), TEXT(""), MB_OK | MB_ICONEXCLAMATION);

        numBytes += byte_num;
        break;
    case FD_CLOSE:
        //MessageBox(hwnd, TEXT("close"), TEXT(""), MB_OK | MB_ICONEXCLAMATION);
        break;
    }
}

The same loop correctly detects messages when I change the program a bit and send data from the client to the client. I've tried messing around bind(), listen(), recv(), but I can't ever get an FD_READ message using node. I've tried with the client and server running on the same computer, as well as different computers on the same local network.

Answer 1

To write data to a socket in Node.js, use socket.write() .

See https://nodejs.org/api/net.html#net_socket_write_data_encoding_callback