Dear Monks,

On my code every time a new user connects to the server I am binding his port into a hash $hash{$port} = $text[1]; for future reference through the: $new_sock->peerport() process, I pick up the port number.

The moment that a new client will connect with the server this value will change, as expected, because $new_sock->peerport() is binded with $new_sock = $sock->accept(). The problem that I am having is that I can not find a way to separate the clients when they are communicating with the server.

Update:

The goal is to be able to change the name of the client who is sending a message to the server, so I can make a small function to send this message to all clients apart from him self.

Working sample of Server Code:

Update the Server code: 3 and Solution with minor problem (It sends the message to all clients, I am trying to fix this sending the message to all clients apart from the one who sends the message.)!

Update: 4 Final!

Final Update on Server and Client works perfect, based on my expectations. The code also controls terminating clients.

#!/usr/bin/perl
use utf8;
use strict;
use warnings;
use IO::Select;
use Data::Dumper;
use IO::Socket::INET; # Non-blocking I/O concept.
use constant ARGUMENTS => scalar 1;
use constant NICKNAME  => scalar 12;
use constant MAXBYTES  => scalar 255;

# flush memory after every initialization
$| = 1;

my $info = $ARGV[0]; # User message IP:PORT;
my $error = "ERROR";
my $newline = "\n";
my %hash = (); # global variable
my %children = ();
my %a_hash = ();
my @clients = ();
my ( $client_data , $server_sock , $buf , $sock , $msg , $new_sock , $
+trans , $readable_handles , $port , $kidpid , $s_hash , $client );

if (@ARGV > ARGUMENTS) {
    print "\nPlease no more than ".ARGUMENTS." input!\n";
    print "\nCorrect Syntax: perl $0 IP:PORT (e.g. 127.0.0.1:5000)\n";
    exit();
}
elsif (@ARGV < ARGUMENTS) {
    print "\nPlease no less than ".ARGUMENTS." input!\n";
    print "\nCorrect Syntax: perl $0 IP:PORT (e.g. 127.0.0.1:5000)\n";
    exit();
}
else {
    
    my $string = index($info, ':');

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

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

    $server_sock = new IO::Socket::INET( LocalAddr => $input[0],
                     LocalPort => $input[1],
                     Proto     => 'tcp',
                     Listen    => SOMAXCONN,
                     Reuse     => 1 ) or die "Could not connect: $!";

    print "\n[Server $0 accepting clients at PORT: ".$input[1]." and I
+P: ".$input[0]."]\n";

    $readable_handles = new IO::Select();
    $readable_handles->add($server_sock);

    while (1) {

    (my $new_readable) = IO::Select->select($readable_handles, undef, 
+undef, 0);
    # conver string to array @$new_readable
    foreach $sock (@$new_readable) {        
        # Check if sock is the same with server (e.g. 5000)
        # if same (new client) accept client socket
        # else read from socket input
        if ($sock == $server_sock) {
        $new_sock = $sock->accept()
            or die sprintf "ERROR (%d)(%s)(%d)(%s)", $!,$!,$^E,$^E;
        $readable_handles->add($new_sock);
        $trans = "Hello version";
        $client_data = &send($trans);
        print "First send: ".$client_data."\n";
        }
        else {
        $buf = <$sock>;
        $port = $sock->peerport();
        print "This is \$sock: ".$sock."\n";
        print "This is \$port: ".$port."\n";
        ($msg) = receive($buf);
        print "First receive: ".$msg."\n";
        my @text = split(/ / , $msg , 2); # LIMIT = 2 Only the first t
+wo gaps split
        #print Dumper(@text);
        if ($text[0] eq "NICK") {
            if (length($text[1]) > NICKNAME) {
            $trans = "".$error." Please no more than ".NICKNAME." char
+acters as nickname!";
            $client_data = &send($trans);
            $readable_handles->remove($sock);
            close($sock);            
            }
            elsif ($text[1] =~ s/\W//g) {
            $trans = "".$error." Special characters detected in the ni
+ckname, please remove them!";
            $client_data = &send($trans);            
            $readable_handles->remove($sock);
            close($sock);
            }
            else {
            $hash{$port}=$text[1];
            #push( @clients , $text[1] );
            #print Dumper(\@clients);
            $trans = "OK";
            $client_data = &send($trans);
            print "Second send: ".$client_data."\n";
            }
        } # End of if ($text[0] eq "NICK")
        elsif ($text[0] eq "MSG") {
            if (length($text[1]) > MAXBYTES) {
            $trans = "".$error." Please remember that message limit is
+ ".MAXBYTES."";
            $client_data = &send($trans);
            print "In case of message over ".MAXBYTES." send: ".$clien
+t_data."\n";
            }
            else {
            # Get all client(s) socket(s)
            my @sockets = $readable_handles->can_write();
            # Send the same message to client(s)
            print Dumper(\%hash);
            foreach my $sck (@sockets) {
                            my $final = "".$text[0]." ".$hash{$port}."
+ ".$text[1]."";
                utf8::encode($final);
                print $sck "".$final."".$newline."";
                print "Third send: ".$final."\n";
                #print STDOUT "The following data send to Client(s): (
+\ ".$buf." \)\n";
            } # End of foreach
            }
        } # End of elsif ($text[0] eq "MSG")
        else {
            print "Closing client!\n";
            # when the client disconnects
            delete $hash{$port};
            $readable_handles->remove($sock);
            close($sock);
        } # End of else condition
        } # End of else condition ($sock == $server_sock)
    } # End of foreach new sock
    } # End of While (1)

    print "Terminating Server\n";
    close $server_sock;
    getc();
} # End of else @ARGV

sub send {
    $_[0] = "".$_[0]."".$newline."";
    utf8::encode($_[0]);
    print $new_sock $_[0];
    chomp ($_[0]);
    #print "The following data send to Cliets: (\ ".$_[0]." \)\n";
    #$client_sock->send($client_packet,MAXBYTES);
    return $_[0];
}

sub receive {
    #$new_sock->recv($client_data,MAXBYTES);
    utf8::decode($_[0]);
    chomp ($_[0]);
    if($_[0] =~ /^$/) {
    print "Data packet received empty!\n";
    print "From host: ".$sock->peerhost()." and port: ".$sock->peerpor
+t()."\n";
    return $_[0];
    }
    elsif ($_[0] !~ /^$/) {
    #print STDOUT "The following data received from Client: (\ ".$buf.
+" \)\n";
    #print "From host: ".$sock->peerhost()." and port: ".$sock->peerpo
+rt()."\n";
    #return $_[0];
    return ($_[0]);
    }
    else {
    $error = "".$error."".$newline."";
    utf8::encode ($error);
    $server_sock->send($error);
    print "Invalid client: ".$new_sock->peerhost()." terminating!\n";
    $readable_handles->remove($sock);
    close($sock);
    }
}

[download]
Update 2, I added the client code for experimentation purposes: 
#!/usr/bin/perl
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 255;

# flush memory after every initialization
$| = 1;

my $info = $ARGV[0]; # User message argv[0]
my $Nickname = $ARGV[1]; # User nickname argv[1]
my ( $kidpid, $line , $client_sock , $server_data , $send );
my $error = 'ERROR';
my $newline = "\n";

if (@ARGV > ARGUMENTS) {
    print "\nPlease no more than ".ARGUMENTS." arguments (ARGV[])!\n";
    print "\nCorrect Syntax: perl $0 'IP:PORT  NICKNAME' (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 $0 'IP:PORT  NICKNAME' (e.g. 127.0.0
+.1:5000 Thanos)\n\n";
    exit();
}
else {
    
    my $string = index($info, ':');

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

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

    # create a tcp connection to the specified host and port 
    $client_sock = IO::Socket::INET->new( Proto    => "tcp",
                      PeerAddr => $input[0],
                      PeerPort => $input[1] 
    ) or die "Can't connect to port ".$input[1]." at ".$input[0].": $!
+\n";

    $client_sock->autoflush(1);    # so output gets there right away 
    print STDERR "[Connected to ".$input[0].":".$input[1]."]\n";
    
    $line = <$client_sock>;
    my $receive = &receive($line);
    #print "First receive: ".$receive."\n";
    if ($receive eq "Hello version") {
    $Nickname = "NICK ".$Nickname."";
    $send = &send($Nickname);
    #print "First send: ".$Nickname."\n";
    $line = <$client_sock>;
    $receive = &receive($line);
    #print "Second receive: ".$receive."\n";
    if ($receive eq "OK") {
        # split the program into two processes, identical twins
        print "Client '".$ARGV[1]."' enter your text here:\n";
        die "can't fork: $!" unless defined( $kidpid = fork() );
        # the if{} block runs only in the parent process 
        if ($kidpid) {
        # copy the socket to standard output 
        while ( defined( $line = <$client_sock> ) ) {
            $receive = &receive($line);
            print "Third receive: ".$receive."\n";
            print "Client '".$ARGV[1]."' enter your text here:\n";
        } # End of While reading (parent)
        } # End of if (parent)
        # the else{} block runs only in the child process 
        else {
        # copy standard input to the socket 
        while ( defined( $line = <STDIN> ) ) {
            chomp ($line);
            my $line = "MSG ".$line."";
            $send = &send($line);
            if ($line =~ /quit|exit/i) {
            $line = "Client request ".$line."";
            my $send = &send($line);
            kill( "TERM", $kidpid );    # send SIGTERM to child 
            }
        } # End of read and send
        } # End of else child
    } # End of if (OK)
    else {
        print "Did not Receive OK!\n";
        exit();
    }
    } # End of if (Hello version)
    else {
    print "Did not receive Hello version!\n";
    exit();
    }
} # End of else @ARGV

sub send {
    $_[0] = "".$_[0]."".$newline."";
    utf8::encode($_[0]);
    print $client_sock $_[0];
    chomp($_[0]);
    #print "The following data send to Server: (\ ".$_[0]." \)\n";
    #$client_sock->send($client_packet,MAXBYTES);
    return $_[0];
}

sub receive {    
    # we can read from socket through recv()  in IO::Socket::INET
    #$client_sock->recv($server_data,MAXBYTES);
    utf8::decode($_[0]);
    chomp($_[0]);
    #print STDOUT "The following data received form Server: (\ ".$_[0]
+." \)\n";
    return $_[0];
}

[download]

I tried to retrieve the socket from two points: my @sockets = $readable_handles->can_write(); or $buf = <$sock>;. Since I this is the first server client that I am creating with the Select function I am not really familiar with it, and I can not find relative information to my problem online.

Any advice would be much appreciated. Thank you all for your time and effort assisting me with my problem.

Seeking for Perl wisdom...on the process...not there...yet!

In reply to How to retrieve the port number on a Multiple TCP Chat Client Server by thanos1983

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