How to listen on a socket for only 10 seconds

[yinglcs2]

Hi,

I read the following code which open a server socket for client request.
However, i would like to know how can I change it so that i just listen for client requestfor 10 seconds, after that, it bows out?



// Create socket for listening for client connection requests.
listenSocket = socket(AF_INET, SOCK_STREAM, 0);
if (listenSocket < 0) {
std::cout << "cannot create listen socket";
return;
}

// Bind listen socket to listen port. First set various fields in
// the serverAddress structure, then call bind().
// htonl() and htons() convert long integers and short integers
// (respectively) from host byte order (on x86 this is Least
// Significant Byte first) to network byte order (Most Significant
// Byte first).
serverAddress.sin_family = AF_INET;
serverAddress.sin_addr.s_addr = htonl(INADDR_ANY);
serverAddress.sin_port = htons(listenPort);

if (bind(listenSocket,
(struct sockaddr *) &serverAddress,
sizeof(serverAddress)) < 0) {
std::cout << "cannot bind socket";
return;
}

// Wait for connections from clients.
// This is a non-blocking call; i.e., it registers this program with
// the system as expecting connections on this socket, and then
// this thread of execution continues on.
listen(listenSocket, 10);

int count = 0;

while (1) {
std::cout << "Waiting for TCP connection on port " << listenPort << " ...\n";

// Accept a connection with a client that is requesting one. The
// accept() call is a blocking call; i.e., this thread of
// execution stops until a connection comes in.
// connectSocket is a new socket that the system provides,
// separate from listenSocket. We *could* accept more
// connections on listenSocket, before connectSocket is closed,
// but this program doesn't do that.
clientAddressLength = sizeof(clientAddress);
connectSocket = accept(listenSocket,
(struct sockaddr *) &clientAddress,
&clientAddressLength);
if (connectSocket < 0) {
std::cout << "cannot accept connection ";
return;
}

Thank you.

[brooksbp]

you'd have to implement a 'clock' in the software. Instead of while(1) do a time check to make sure that the loop stops once 10 seconds have been reached.

[hod139]

You can include time.h, and do the following:


clock_t finish;
finish = clock() + 10*CLOCKS_PER_SEC;
while (clock() < finish);

[kpatz]

Look up select() in the man pages. The select() function lets your program wait for an event (such as a connection request) on one or more file descriptors (sockets in your case). There is a timeout parameter that you can use to achieve your 10 second timeout as well.

The advantage of using select over a while loop with a non-blocking listen call is that your program will sleep for the 10 seconds (or until a connection request is received on the socket) rather than looping and consuming CPU cycles.

Select is also handy for handling multiple connections in a single thread. Say if you have a daemon listening on a socket, and multiple clients connect to the socket, select() will return which socket(s) have pending actions on them so your program can act on them.