Do I need to setup a UDP connection specifically to use recv? To do this do I only need to specify 'Proto'=>'udp' when opening the socket?

I am attempt to read a string back through the <$t_socket> -it is a name that I need to find a eq match for - the link below has a better description of my project:

http://www.perlmonks.org/?node_id=472004

Essentially I am trying to match input given to me by a First process, if I match this input in the Second process I send it to the Third process to see if I have yet another match. However if the First/Second match is not confirmed by the Third process, then I need to respond to the Second to find another match.

Sending the data from First, to Second, to Third works fine.

My problem comes in being able to establish a connection "downstream" (Third, to Second, to First) using the same set of sockets that I originally used to send data "upstream". In short, I cannot seem to pick up a response from Third to Second, and then from Second to First.

The code for my Third process is appended below - as you can see I am adding a newline at the end of the string before I send it back to the Second process - but for some reason the while(<$t_socket>){...} loop never executes - either it is indefinitely waiting on the <$t_socket> or it is skipping the loop altogether.

use IO::Socket;
use strict;
use warnings;

my $PORT = shift or die "Please specify First port number\n";

#my $file = shift or die "Please specify input file\n";

my $socket = IO::Socket::INET->new('LocalPort' => $PORT,
                       'Proto' => 'tcp',
                       'Listen' => 2)
    or die "Third: Can't create socket to Second($!)\n";

my $match = "brenna";
    
print "Third listening\n";
while (my $second = $socket->accept) 
{
    #setup acknowledgement message to Second
    my $host = gethostbyaddr($second->peeraddr, AF_INET);
    my $port = $second->peerport;
    
    while (<$second>) 
    {
        my $name = $_;
        chomp($name);
        
        print "[$host $port] $name\n";
        #print $socket "$.: $name\n";

        if($name eq $match)
        {    
            print "Third sending \"$name\" to Second\n";
            print $socket "$name\n";
            #close $second or die "Can't close ($!)\n";
        }
    }
}
die "Third: Can't accept receive socket from Second($!)\n";
[download]

Any help/advice you can offer to help me figure this out would be much appreciated!