joyent/libuv — comment on commit c0792e54052bd3222c3b00e45f7e81c87187504a
File:  line 0
By igorzi:

Actually, IPPROTO_TCP + TCP_KEEPALIVE does map to SIO_KEEPALIVE_VALS + tcp_keepalive.keepalivetime (for API compatibility). You can try setting keep-alive delay through WSAIoctl, and then read it with getsockopt(IPPROTO_TCP,TCP_KEEPALIVE). But yeah we should use winsock WSAIoctl function instead as recommended by MSDN.