======================================================================

#!/usr/bin/perl
# FILE: try_socket_perl_monks.pl
#
use warnings;
use strict;

print "PROGRAM: try_socket_perl_monks.pl \$ARGV[0]=$ARGV[0]\n";

my $MySocket; # socket
my $t; # time

use IO::Socket; 

if ($ARGV[0] eq "A")
{
    $MySocket=new IO::Socket::INET->new(Proto => 'udp',
                                        PeerAddr=> '192.168.22.30',
                                        PeerPort=>8005, 
                                        LocalAddr=> '192.168.21.28',
                                        LocalPort=>8006);
   print "Configuration A, \$MySocket=$MySocket\n";
}
elsif($ARGV[0] eq "B")
{
   my $MySocket=new IO::Socket::INET->new(Proto => 'udp',
                                          PeerAddr=> '192.168.21.28',
                                          PeerPort=>8006, 
                                          LocalAddr=> '192.168.22.30',
                                          LocalPort=>8005);
   print "Configuration B, \$MySocket=$MySocket \n";
}
elsif($ARGV[0] eq "C")
{

   my $MySocket=new IO::Socket::INET->new(Proto => 'udp',
                                          PeerAddr=> '192.168.20.223',
                                          PeerPort=>8006, 
                                          LocalAddr=> '192.168.21.28',
                                          LocalPort=>8005);
   print "Configuration C, \$MySocket=$MySocket \n";

}
else
{

   print "Passed argument error \n";

}

if (defined($MySocket))
{  
   print "\$MySocket = $MySocket\n";
}
else
{
   print "\$MySocket not defined\n";
}

my $msg = "This is a test message 12345678901234567890123456789012345678901234567890\n";
$MySocket->send($msg);
$MySocket->send($msg);
$MySocket->send($msg);
$MySocket->send($msg);

print "After the sending of the message\n";

my $text;

my $more = 1;

my $retries = 0;

do
{
   eval {
         local $SIG{ALRM} = sub{++$retries and die "timeout\n" };
         alarm(3);
         $retries++;
         print "above the recv, \$retries=$retries\n";
         $MySocket->recv($text, 128) or die "recv failed: $!";
         alarm(0);
         print "\$retries=$retries, length(\$text)=" . length($text) . "\n";
        };
   print "retrying \$retries=$retries\n";
   
} while $retries < 4;

print "END OF PROGRAM\n\n";

##</code><code>##

PROGRAM: try_socket_perl_monks.pl $ARGV[0]=A
Configuration A, $MySocket=IO::Socket::INET=GLOB(0x818416c)
$MySocket = IO::Socket::INET=GLOB(0x818416c)
After the sending of the message
above the recv, $retries=1
retrying $retries=2
above the recv, $retries=3
retrying $retries=4
END OF PROGRAM

##</code><code>##

PROGRAM: try_socket_perl_monks.pl $ARGV[0]=B
Configuration B, $MySocket=IO::Socket::INET=GLOB(0x81842e4) 
$MySocket not defined
Can't call method "send" on an undefined value at ./try_socket_perl_monks.pl line 59

##</code><code>##

PROGRAM: try_socket_perl_monks.pl $ARGV[0]=C
Configuration C, $MySocket=IO::Socket::INET=GLOB(0x81842e4) 
$MySocket not defined
Can't call method "send" on an undefined value at ./try_socket_perl_monks.pl line 59