Maybe this can help
AcceptEx function
BOOL AcceptEx(
_In_ SOCKET sListenSocket,
_In_ SOCKET sAcceptSocket,
_In_ PVOID lpOutputBuffer,
_In_ DWORD dwReceiveDataLength,
_In_ DWORD dwLocalAddressLength,
_In_ DWORD dwRemoteAddressLength,
_Out_ LPDWORD lpdwBytesReceived,
_In_ LPOVERLAPPED lpOverlapped
);