How do I check if the connection is still alive

[jaro]

Hi there,

I'm wondering is there a function out there that would tell if the socket connection is still alive(or connected).


basically I use some of this to connect to the other "station" ( don't know if these code below would help,but I just want you to know)

gethostbyname(HOST)
//..............
clientService.sin_addr=*((struct in_addr*)h->h_addr);	 	/* IP address for hostname */
clientService.sin_port = htons("4040");			/* smtp port */
clientService.sin_family = AF_INET;  			/* internet */
//................
ConnectSocket = socket(AF_INET, SOCK_STREAM, 0);
connect( ConnectSocket, (struct sockaddr*) &clientService, sizeof(struct sockaddr) )
//...................

Currently the programs works fine,it is able to retreive and process message from the other "station" (w/c acts a workspaceserver).
The problem is that when I disconnect my pc from the network (by pulling out the network cable), the program still run as if it is still connected to the other "station".

How do I check if the connection is still alive?

Regards,
Jaro

[redhead]

The connection, as you call it, has a 120 sec. timeout delay, so the program will run for atleast 2 minuts after pulling out the cable, befor it detects a loss in network activity.

[kyoryu]

What are you using to check the socket for available data/receive the data?

EDIT:

Since your other thread asked about poll(), I'm going to assume you're poll()ing your sockets.

If that's the case, the way to determine if you have a disconnected socket is to see if poll() returns either POLL_READ or POLL_HUP, and a subsequent read() from the socket returns 0 bytes.

The status of POLL_HUP and POLL_READ is *not* consistent between OS's, and is somewhat undefined. What either will tell you, however, is that if you read from the socket you won't block. On an open socket, this means that there's data available.

Doing a read from that socket, once you know it won't block, and getting zero bytes then tells you that the socket is closed.

[jaro]

Just found out that i can't use poll() under Windows programming.
I've started to read/work on select() and i hope that this will be the solution.
I'll post again if I encounter some problem along the way.
many thanks to those who reply to my post.
regards,
jaro

[DJMaze]

See "Windows Socket 2" system.
the win32 sdk help has sock2.hlp which contains all the needed info.