The helper then enters its main loop, transferring client IPADM commands over the socket to the daemon and piping responses back.

Notice that the helper is free to use signals, in particular SIGALRM, so it can timeout network reads and inform the client.

sub timeout {print "1 Socket Timeout\n$EOFn"; $SIG{ALRM} = \&timeout}
$SIG{PIPE} = sub {print "2 Pipe Error.\n$EOF\n"};

my $sock = IO::Socket::INET->new( PeerAddr => $ARGV[0],
                  Proto => 'tcp', PeerPort => $ARGV[1]);
print +((defined $sock) ? "0 Connect OK" : "3 Connect Failed"), "\n$EOF\n";

while (1) {

    while(<STDIN>) {
        print $sock $_;         # send parent's command/data to daemon
        last if /^$EOF$/;
    }

    my(@data) = ( );
    $SIG{ALRM} = \&timeout;     # reset handler
    alarm 60;

    while (<$sock>) {
        push @data, $_;         # accumulate command's reply
        last if /^$EOF$/;
    }

    alarm 0;
    print (/^$EOF$/ ? @data : "4 Daemon Failure\n$EOF\n");

} # whilend

19.3. The Perl/Tk IPADM Client, ipadm		19.5. The IPADM Daemon, ipadmd