#!/usr/bin/perl
#TCP Client code
use utf8;
use strict;
use warnings;
use Data::Dumper;
use IO::Socket::INET;
use constant ARGUMENTS => scalar 2;
use constant NICKNAME => scalar 12;
use constant MAXBYTES => scalar 25;

$| = 1;

my ($client_socket,$server_data,$client_packet,$result);
my $info = $ARGV[0]; # User message argv[0]
my $Nickname = $ARGV[1]; # User nickname argv[1]
if ($Nickname =~ s/\W//g) {
    print "Special characters detected, please remove them!\n";
    exit();
}

if (@ARGV > ARGUMENTS) {
    print "\nPlease no more than ".ARGUMENTS." arguments (ARGV[])!\n";
    print "\nCorrect Syntax: perl Exercise_5_Client.pl 'IP:PORT  NICKN
+AME' (e.g. 127.0.0.1:5000 Thanos)\n\n";
    exit();
}
elsif (@ARGV < ARGUMENTS) {
    print "\nPlease no less than ".ARGUMENTS." arguments (ARGV[])\n";
    print "\nCorrect Syntax: perl Exercise_5_Client.pl IP number\n
           (e.g. 127.0.0.1) port number (e.g. 5000)\n
           Nickname (e.g. Thanos)\n\n";
    exit();
}

if (length($Nickname) > NICKNAME) {
    print "\nPlease no more than ".NICKNAME." characters as nickname!\
+n";
}

else {
    
    my $string = index($info, ':');

    if ($string == '-1') {
    die "Please add ':' in your input - ".$info."\n";
    }

    my @input = split( ':' , $info );

    # creating object interface of IO::Socket::INET modules which inte
+rnally creates
    # socket, binds and connects to the TCP server running on the spec
+ific port.
    $client_socket = new IO::Socket::INET (
    PeerHost => $input[0],
    PeerPort => $input[1],
    Proto => 'tcp',
    ) or die "ERROR in Socket Creation : $@!\n";

    $client_socket->autoflush(1);  # Send/receive immediately
    $client_packet = "\0";
    my $first = &send($client_packet);
    my $receive = &receive();
    $client_packet = $Nickname;
    my $second = &send($client_packet);
    my $receive_2 = &receive();
    if ($receive_2 ne "OK") {
    $client_packet = "ERROR";
    &send($client_packet);
    print "Client received unexpected message terminating!\n";
    exit();
    } # End of if receive eq OK
  MSG:
    print "Please be aware maximum length 255 characters!:\n";  
    do {
    print "Send this text to clients:\n\n";
    chomp ($result = <STDIN>);
    if (length($result) >= MAXBYTES) {
        print "\nYou have exceeded the limit of characters ".length($r
+esult)."!\n\n";
        goto MSG;
    }
    else {
        my $new_line = "\n";
        $client_packet = "".$result."".$new_line."";
        utf8::encode($client_packet);
        my $third = &send($client_packet);
        my $receive_3 = &receive();
        print "This is received_3: ".$receive_3."\n";
    }
    } until ($result eq "END" || "end");
    print "Goodbye\n";
    $client_socket->close();
} # End of else condition (ARGV[])

sub send {
    $client_socket->send($client_packet);
    return $client_packet;
}

sub receive {    
    # we can read from socket through recv()  in IO::Socket::INET
    $client_socket->recv($server_data,MAXBYTES);
    print "The following data received form Server: (\ $server_data \)
+ ";
    print "\n";
    return $server_data;

}
$| = 1;
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I tried to enter another goto condition after end of do loop but not successfully. If I do so I lock my self in an infinity loop that I do not send messages or receiving messages, not even able to exit loop by typing end.