On 03/27/2013 01:00 PM, Oleg Kurchenko wrote: > Hello, > > it seems that communicating, described in > http://www.ararat.cz/synapse/doku.php/public:howto:activeconnection > does not help. > > I made a simple demo of tcp client, the code is shown below. > > After I connected to server and took out the LAN cable and there is a > red cross on the connection icon in the system tray, I can for about > 30 seconds to send messages, and it does not get errors! > > > Can this be fixed? >
No. TCP is a protocol designed to work on unreliable communication links and will recover from errors. So a broken link is not immediately an error on the TCP layer. There are timeouts that make that TCP will consider a link dead after a certain delay. The red cross on the connection icon you are seeing is on a completely different layer of the network protocol (physical layer) and has nothing to do with TCP. In more complex configurations you can pull out a cable and communication will just go on over a different link without the TCP communication ever being broken down. A nice example is wifi roaming. So if you need to know when a network cable is pulled out, you need to use a different method. Ping your local router (ICMP is not using TCP) with a short timeout (mind alternate routes!) or get your network card status using some OS dependent calls. Ludo ------------------------------------------------------------------------------ Own the Future-Intel® Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d _______________________________________________ synalist-public mailing list synalist-public@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/synalist-public
