I am trying to write a simple server in a rather standard way:

In princip it works, you can connect with a telnet client, send data from the client to the server and vice versa. But there is a problem sending data from the server to the client. The data is not sent (print $new_sock $_;) until the server recieves a line from the client. Somthing is blocking. As you can see in the inactive lines, I tried all sort if thing to unblock this, to no avail. I seem to miss something concerning blocking of sockets.

use IO::Socket;
use warnings;
use strict;

#use Term::ReadKey;

my $flush = 1;

my $sock = new IO::Socket::INET (
                                 LocalHost => 'PK5',
                                 LocalPort => '7070',
                                 Proto => 'tcp',
                                 Listen => 1,  # max concurrent caller
                                 Reuse => 1,  
                                );
die "Could not create socket: $!\n" unless $sock;
print "SERVER Waiting for client connection on port 7070\n";

my $new_sock = $sock->accept();
#  $new_sock->autoflush(1);              # so output gets there right 
+away
my $peer_address = $new_sock->peerhost();
my $peer_port    = $new_sock->peerport();
#     $new_sock->blocking(0);
#     $| = 1;

print "Accepted New Client Connection From : $peer_address, $peer_port
+\n";


my $pid = fork();

if (not defined $pid) {print "resources not available.\n";} 
elsif ($pid == 0) { # child, receiver
   while(<$new_sock>) {
     print $_;
     if($_ eq "end\n"){last;}
   }
   exit(0);
} else { # parent, sender
  

while(<>){
#     $new_sock->flush;
# ReadMode 1;
     print $new_sock $_;
#     $new_sock->flush;
     if($_ eq "end\n"){last;}   
   }

   waitpid($pid,0);
}

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In reply to Bidirectional Socket, Blocking by DanielPHuber

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