The example client:

use strict ;
use warnings ;

use IO::Socket::INET ;
use Socket ;

use IO::Select ;

select STDERR ; $|= 1;
select STDOUT ; $|= 1;

my $rcvtimeo = 3 ;

my $IP = 'localhost' ;

my $f = 0 ;
for my $f (1..6) {
  my $try = "Fit $f" ;

  my $socket = new IO::Socket::INET (PeerAddr  => $IP,
                                     PeerPort  => 3575,
                                     Proto     => 'tcp',
                                    )
                          or die "Couldn't connect to Server $! ($@)\n
+" ;

  print STDERR "Opened connection for $try\n" ;

  sleep(1) ;
  print STDERR "Sending request: $try\n" ;

  defined $socket->send($try)                  or die "send failed: $!
+" ;

  my $wait = IO::Select->new() ;
  $wait->add($socket) ;

  for my $r (1..2) {
    if ($wait->can_read($rcvtimeo)) {
      my $recv_data ;
      defined $socket->recv($recv_data, 10240) or die "recv $r failed:
+ $!" ;  
      print STDERR "RECEIVED-$r: '$recv_data'\n" ;
    }
    else {
      print STDERR "RECEIVED-$r: timed out\n" ;
      last ;
    } ;
  } ;

  close $socket ;
} ;
[download]

It's worth making friends with IO::Select. Note that $s->can_read() will return a list of all the sockets associated with the IO::Select object $s, which are ready to be read from (or have outstanding errors). With only one socket it's not necessary to process that list explicitly !

The above can be run against this example server:

use strict ;
use warnings ;

use IO::Socket::INET ;
use Socket ;

select STDERR ; $|++ ;
select STDOUT ; $|++ ;

my $server = IO::Socket::INET->new(LocalPort => 3575,
                                   Reuse     => 1,
                                   LocalHost => 'localhost',
                                   Listen    => 5) 
                          or die "Couldn't create Server $! ($@)\n" ;

my @ignore ;

foreach my $action (2,  # receive request, send 2 replies & close
                    1,  # receive request, send 1 reply   & close
                    0,  # receive request, send 0 reply   & close
                   -1,  # receive request, ignore         & DON'T clos
+e
                   -2,  # ignore completely               & DON'T clos
+e
                   ) {
  my $client = $server->accept() ;

  if (!defined($client)) {
    print STDERR "Accept failed: $! ($@)" ;
    next ;
  } ;

  print "Connection accepted (action = $action)\n" ;

  my $request = 'connection' ;

  if ($action > -2) {
    defined $client->recv($request, 1024)   or die "recv request faile
+d $!" ;
    print STDERR "Request received: '$request'\n" ;
  } ;

  if ($action < 0) {
    push @ignore, $client ;    # Not to be closed
    print STDERR "Ignoring $request, but leaving connection open\n" ;

    next ;
  } ;

  for my $r (1..2) {
    if ($r <= $action) {
      my $reply = "$request -- reply $r" ;
      defined $client->send($reply)         or die "send reply-$r fail
+ed $!" ;
      print STDERR "Sent '$reply'\n" ;
      sleep(2) ;
    }
    else {
      print STDERR "Not sending reply $r\n" ;
    }
  };
  close $client ;
  print STDERR "Connection closed\n" ;
} ;

print STDERR "Ignoring everything" ;
while(1) {
  sleep(10) ;
  print STDERR "." ;
} ;
[download]