How to recognize that the server is currently unavailable?

compext · 12-13-2006, 07:38 PM

I wrote 2 simple codes between a client and a server (run as daemon), the TCP connection is established seen from netstat. However, when the server is rebooted, the client is still pending in the "recv" function (it should return a value<=0, right?). While it is OK to kill the server with "killall". Is there any flags or options? Thanks.

IBall · 12-13-2006, 08:29 PM

Welcome to LQ!

Try looking at the "select" function. This will return when one of multiple events occur, such as the socket being readable or writable, the connection is terminated at the other end, etc.

--Ian

compext · 12-13-2006, 08:59 PM

I'm using a blocking socket, so the select function may not affect the "recv" function.

Wim Sturkenboom · 12-14-2006, 11:50 PM

While ago that I programmed sockets. Your client will not get any 'messages' if you don't stop the server application in a proper way. So when the server app is killed, it must close sockets etc.

Select and blocking sockets go very well together.

Code:

while(1)
{
  setup select
  call select (wait till something happens)
  if socket can be read, 
    read from socket
}