google: TCP OPTION KEEPALIVE http://tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/
You would be best with an application level timeout, which would send an application enquiry (heartbeat) from the laptop to the server. Waking up from sleeping, the application would send the next heartbeat. (any data has the same effect, the problem was that the laptop was silent). That would get an immediate response, from the remote OS, that the TCP connection was dismantled ages ago, whilst the laptop was comatose. That would appear to the SSL BIO as select_says_fd_is_readable and when it reads from the socket-fd, an error eof. Then SSL knows and lets you know too. If you dont want to change the application protocol, you can have the OS do exactly that for that socket. No DATA.data will appear on the application side of the socket-fd, just hidden TCP control messages, on the network side. That will also keep any NAT router happy. In an ideal world, the wake-from-sleep should do that for each TCP connection. Maybe it leaves it for each app to figure it out on its own. Graham 2009/10/29 Parimal Das <parimal....@webyog.com> > > When it has downloaded some 2MB data, I closed my laptop lid (OSX induced > sleep) > After 5 minutes when i open my laptop, the process hangs at the same place > as before. > >
