in reply to Timeout Socket recv on UDP... on windows

How about using a select based approach? Something like: 

...(set up socket)...
my $end = time + 15*60;
my $rin;
vec($rin, fileno($hSocket), 1) = 1;
while (1) {
    my $timeleft = $end - time;
    last if ($timeleft <= 0);
    my ($nfound, $t) = select(my $rout = $rin, undef, undef, $timeleft
+);
    last if ($nfound == 0); # either timeout or end of file
    # read from socket here
}

[download]

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Re^2: Timeout Socket recv on UDP... on windows
by shunyun (Novice) on Jan 26, 2008 at 16:15 UTC
    pc88mxer, I gotta look into this more, as I'm not sure what this is doing. Is this checking for whether $hSocket is undef (see my other reply, regarding checking if accept has been called)? I'll plug this in, read up, and try. Not necessarily in that order. Thanks
[reply]
      The select call will wait $timeleft seconds or until there is data available to be read on the socket, whichever occurs first. This allows you to implement non-blocking I/O.

      This raises a good point: you have a number of tcp and udp sockets. Do you need (or want) to operate them at the same time (i.e. multiplex the I/O)? If so, you can either do that with threads or also with select.

      Final point... select can also be used to determine if a socket is ready to accept an incoming connection.

[reply]
[d/l]
[select]
        Thanks folks. Both the non-blocking and select responses helped. I've got working code now; I ended up not needing to establish non-blocking, as pc88mxer's guidance put me in the right place. Here's my final working routine:

        Sorry that this looks ugly here. click download to see correct format. 

        sub ListenOnUDP
{
    my $end = time + $timeout;
    print "PortListen on $strFQDN ($address) at $strProtocol\/$intList
+enPort\n";
    # Open a udp port
    my $hSocket = IO::Socket::INET->new(LocalPort=>$intListenPort, Pro
+to=>$strProtocol, Timeout=>$timeout)
    or die "Can't create UDP socket: $@";
    
    # Wait for a connection ($hSocket is undef until an accept call is
+ made).
    my $rin = '';
    vec($rin, fileno($hSocket), 1) = 1;
    while (1) {
        my $timeleft = $end - time;
        if ($timeleft <= 0) {
            print "No connection: Timed out after $timeout seconds.\n"
+;
            last;
        }
        my ($nfound, $t) = select(my $rout = $rin, undef, undef, $time
+left);
        if ($nfound == 0) { # either timeout or end of file
            print "No connection: Timed out after $timeout seconds.\n"
+;
            last;
        }
        
        # Connection exists; Receive data, open a response port, respo
+nd, then close both ports.
        my ($datagram,$flags);
        while ($hSocket->recv($datagram,42,$flags)) {

            my $ripaddr = $hSocket->peerhost;
            my $rport = $hSocket->peerport;
            print "RECIEVE_FROM-TO, $ripaddr, $strProtocol\/$rport, $a
+ddress, $strProtocol\/$intListenPort, message=$datagram\n";

            # UDP is connectionless, so try to open a connection going
+ back the other way, then send a response.
            # NOTE: This requires a predefined 'remote' port. Pass via
+ commandline; default is $intSendPort
            my $hResponseSocket = IO::Socket::INET->new(Proto=>$strPro
+tocol,PeerHost=>$ripaddr,PeerPort=>$intSendPort);
            print "SEND_FROM-TO, $address, $strProtocol\/" . $hRespons
+eSocket->sockport . ", $ripaddr, $strProtocol\/$intSendPort, message=
+PONG!\n";
            $hResponseSocket->send("PONG!");
            close($hResponseSocket);
            last;
        }
        last;
    }
    close($hSocket);
}

        [download]

        Again, thanks folks, this solved my problem. Anyone interested in helping me QA and test my final script on other platforms?

[reply]
[d/l]

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