socket programming problem...???

arunka · 10-06-2005, 07:38 AM

hi all

i have written a client / server program,
In the server i am waiting for a connection and after accepting the connection from a remote client i am sleeping for 5 sec, wiyhin this interval
i have unplugged the network cable ...
After the sleep is over i sent some data using send.
The perror after send is giving succes.
(Remember i have unplugged the cable...!!!)
i want to know a mechanism from which i should know before sending only whether the cable is plugged in or not..???

Thanks in advance...

-Arun KA

rjlee · 10-06-2005, 12:09 PM

You need to use a TCP socket, rather than a UDP socket.

With UDP, no acknowledgement is sent for packets and no error correction is done; this makes the transport very fast but not very reliable. With TCP, everything is acknowledged and checksums exchanged; this can lead to lag when communicating over lossy connectors, but ensures that everything that is sent is actually received (or the connection dropped).

arunka · 10-10-2005, 07:13 AM

i am using TCP sockets only. but still the problem is same.

AlonsoTheBonzo · 10-10-2005, 06:45 PM

Not sure, but im guessing it has something to do with the fact that you are writing to a valid file descriptor (the socket) and nothing is actually physically sent until the buffer is flushed / closed. Perhaps you could try a flush before the send? Interesting problem - if you find an answer please post it.

greghua · 10-11-2005, 08:08 AM

Did you use the "stay alive" option. I think the possible reason is the period that you unlpuged the cable is too short. The protocol usually waits a pretty long time before it break the connect. You can check Steve's "Unix Network programming" for more details.

Quote:

Originally posted by arunka
hi all

i have written a client / server program,
In the server i am waiting for a connection and after accepting the connection from a remote client i am sleeping for 5 sec, wiyhin this interval
i have unplugged the network cable ...
After the sleep is over i sent some data using send.
The perror after send is giving succes.
(Remember i have unplugged the cable...!!!)
i want to know a mechanism from which i should know before sending only whether the cable is plugged in or not..???

Thanks in advance...

-Arun KA