ioctlsocket reporting 0 bytes available to read

[wanting2learn]

I'm trying to track down an issue I have with windows sockets.

I have an client and server which I use to send simple text commands data back and forth.

I have a non-blocking socket which I use to send data from my client to the server

int err = send( socket, stringToSend.c_str(), stringToSend.size(), 0 );

I then use the following to check if there is any data on the socket to read:

if (SOCKET_ERROR != ioctlsocket( socket, FIONREAD, (DWORD*)&nLength ))
{
    if (0 < nLength)
    {
         err = recv( socket, buf, nLength, 0 );

         //blah blah
    }

        //blah blah
}

Now I have a strange problem.
1. When I send the first piece of data from client to server I am able to receive a response from the server.
2. Then I try to send the smae piece of data again, but this time ioctlsocket always reports that 0 bytes is available to read from the socket (nLength is always 0).

The strange thing is that if I use wireshark I can see that the server has actually sent data to the client.

What would cause ioctlsocket to report that nLength = 0 whenever I can see data sent via wireshark???

Thanks

[kooth]

When using sockets you are never guarenteed that the number of bytes you send or receive will be sent all at once. You must put your sends and receives in a loop! This is because even though the IP layer tries to negotiate to use the same number of bytes on each side, they aren't always able to do so.

So, I would change the name of your variable from "err" to "bytesReceived" or something like that.