#!/usr/bin/perl -Tw
use strict;
BEGIN { $ENV{PATH} = "/usr/bin:/bin" }
use Socket;
use Carp;
my $EOL = "\015\012";

sub logmsg { print "$0 $$: @_ at ", scalar localtime(), "\n" }

my $port  = shift || 2345;
die "invalid port" unless $port =~ /^ \d+ $/x;

my $proto = getprotobyname("tcp");

socket(Server, PF_INET, SOCK_STREAM, $proto)    || die "socket: $!";
setsockopt(Server, SOL_SOCKET, SO_REUSEADDR, pack("l", 1))    
                                                || die "setsockopt: $!";
bind(Server, sockaddr_in($port, INADDR_ANY))    || die "bind: $!";
listen(Server, SOMAXCONN)                       || die "listen: $!";

logmsg "server started on port $port";

my $paddr;

$SIG{CHLD} = \&REAPER;

for ( ; $paddr = accept(Client, Server); close Client) {
    my($port, $iaddr) = sockaddr_in($paddr);
    my $name = gethostbyaddr($iaddr, AF_INET);

    logmsg "connection from $name [",
            inet_ntoa($iaddr), "]
            at port $port";
            
    print Client prelen( "Hello there, $name, it's now ", scalar localtime(), $EOL );
    print Client prelen( 'backslash \n__'."\n" );
    print Client prelen( 'backslash \r\n'."\r\n" );
    print Client prelen( 'backslash EOL_'.$EOL );
}
sub prelen {
    my $str = join '',@_;
    my $len = length $str;
    return "($len+6)$str";
}
##</code><code>##

#!/usr/bin/perl -w
use strict;
use Socket;
my ($remote, $port, $iaddr, $paddr, $proto, $line);

$remote  = shift || "localhost";
$port    = shift || 2345;  # random port
if ($port =~ /\D/) { $port = getservbyname($port, "tcp") }
die "No port" unless $port;
$iaddr   = inet_aton($remote)       || die "no host: $remote";
$paddr   = sockaddr_in($port, $iaddr);

$proto   = getprotobyname("tcp");
socket(SOCK, PF_INET, SOCK_STREAM, $proto)  || die "socket: $!";
connect(SOCK, $paddr)               || die "connect: $!";
binmode SOCK or die "binmode $!"; ## no effect on client side
while ($line = <SOCK>) {
    my $length = length $line;
    print "($length)$line";
}
close (SOCK)                        || die "close: $!";
exit(0);

__END__
$ perl client.pl
(65)(59+6)Hello there, localhost, it's now Wed Sep 14 03:53:10 2011
(21)(15+6)backslash \n__
(22)(16+6)backslash \r\n
(22)(16+6)backslash EOL_