[tpm] UDP broadcast/receive problems

[Fulko Hew]

I'm trying to accomplish what I thought was easy, and yet I can't get it to
work.

I have a number of devices that listen on UDP port 9999.
So I want to send a broadcast message to my network and see all
of their specific responses, so I can collect the list of IP addresses
(for subsequent messaging).
For a single device, it looks like this:

192.168.1.149:port  -->  255.255.255.255:9999
192.168.1.149:port  <--  192.168.1.130:9999

So I've tried a number of things starting from a single socket all the way
to
a send socket and a second receive socket, but I can never read the
response that's sent.

My last attempt is this code snippet... can anyone tell me what's wrong ?


$out = IO::Socket::INET->new(
    PeerPort  => 9999,
    PeerAddr  => inet_ntoa(INADDR_BROADCAST),
    Proto     => udp,
    ReuseAddr => 1,
    Broadcast => 1)
        or die "Can't bind : $@\n";

my $lport = $out->sockport();           # get the local port that was
assigned
print "sending from $lport\n";

$in = IO::Socket::INET->new(
    PeerPort  => 9999,
    LocalPort => $lport,
    Proto     => udp,
    ReuseAddr => 1)
        or die "Can't bind : $@\n";

my $s = IO::Select->new($in);
$s->add($out);

$out->send('hello') or die "send: $!";

while ($i++ < 100) {
    my @ready = $s->can_read(1);
    foreach (@ready) {
        die("readable but nothing read\n") unless defined($_->recv($rsp,
1024));
        print $rsp;
    }
}
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.pm.org/pipermail/toronto-pm/attachments/20201009/c38887b0/attachment.html>