hello monks,i have writen a code for a udp client,it just sends a packet to the server. the problem is that i have to press Enter/return two times to get the packet on the other side.and one more question, if we have data more than MSS of UDP packet which is 534 bytes, how do we send it? e.g. if the client requests a file, how do we send it back? any help is appreciated. the code of client:

#!/usr/bin/perl
use IO::Socket;

my $sock = &rdt_connect($ARGV[0],$ARGV[1]);
$msg = "get $ARGV[2]";
$sendmsg = &rdt_send($msg);
print length($sendmsg);
&sendall($sock,$sendmsg);


sub rdt_connect {

    #takes necessary parameters, creates socket and connects to that c
+lient.
    my ($serverconnect,$portconnect) = @_;
    $proto = 'udp';
    $socket = IO::Socket::INET->new (PeerAddr=>$_[0],PeerPort=>$_[1],P
+roto=>'udp') or die "Can't Connect $!";
    return $socket;
}

sub rdt_send{
    #makes packet and sends it to the socket.
    my $datatosend = @_;
    $lengthpayload = length($_[0]);
    $r = 'R';$d='D';$t='T';$one=1;$point = '.';$zero=0;$null1=00000000
+;$null2=00000000;$null3=00000000;$null4=00000000;$null5=00000000;$nul
+l6=00000000;$null7=00000000;
    $protocol = pack("a"x6,$r,$d,$t,$one,$point,$zero);
    $packetheader = pack('N3 n N3 n',$null1,$null2,$null3,$lengthpaylo
+ad,$null4,$null5,$null6,$null7);
    #$packetpayload = $packetheader.$datatosend;
    $packetpayload = pack('a*',$_[0]);  
    $tobuffer = ($protocol.$packetheader.$packetpayload);
    return $tobuffer;
}

sub sendall{
    
    my ($socket,$packet) = @_;
    if ($packet ne ''){$_[0]->send($_[1]) or die "Send error: $!\n";}
}
[download]

and the server code

#!/usr/bin/perl -w
use IO::Socket;

    ($server,$port1) = &rdt_listen($ARGV[0]);
      
      print"LISTENING ON PORT $port1\n";
    
    $serverhasdata = &select($server);
    
        
    ($thehost,$request) = &rcv_from($serverhasdata);
    
    $thedata  = &statmachine_send($request);
    
    @payloadwoh = &statemachine_rcv($thedata);
    @payld = &rdt_recv(@payloadwoh);
    @payloadwoh = split(/\t/,$line);
                

    print"u have got a request from:$thehost and the request is:@paylo
+adwoh\n\n";



sub rdt_listen{
    #takes necessary parameters creates a socket and listens on that p
+ort.
    my $port1 = $_[0];
    $protocol = 'udp';
    $socket1 =  IO::Socket::INET->new(LocalPort=>$port1,Proto=>$protoc
+ol)or die "Cannot Listen On The Socket $@";
        return $socket1,$port1;
    }
    
sub select{

    #it selects the socket(socket is given as a parameter) and receive
+s data from that socket
    my ($rcvsocket) = @_;
    $_[0]->recv($buf,534);
    if ( length($buf) != 0 ){

    return $_[0];

    }
}

sub rcv_from{

    #takes data from the socket which is selected by the select functi
+on
    my $sock = @_;
    while($_[0]->recv($msg, 534)){
    my($port, $ipaddr) = sockaddr_in($_[0]->peername);
    $hishost = gethostbyaddr($ipaddr,AF_INET);
    return ($hishost,$msg);
}
}

sub statmachine_send {
        #takes data from rcv_from and returns it
        my $comingdata = @_;
        return $_[0];        
}    

sub statemachine_rcv {
    
    #it takes the packet from the statmachine_send function;
    my $packet = @_;
    #unpack the packet    
    my($r,$d,$t,$one,$point,$zero,$null1,$null2,$null3,$lengthpayload,
+$null4,$null5,$null6,$null7) = unpack('a3 C3 N3 n N3 n',$_[0]);
    $lengthpayload1 = $lengthpayload;
    @payload = unpack('a*',substr($_[0],34,$lengthpayload1+34));
    #check if payload contains data or its empty    
    if ( length(@payload) != 0){
        return @payload;
    }else { return ;}

}

sub rdt_recv{
    #it reads data from recive buffer.
    my @read = $_[0];
    while (@read){
    return "$_[0]";    
    }
}
[download]

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