CKAGES / SETUP ===========================================================
use warnings;
use strict;

BEGIN {
  $ENV{ENV} = '';
  $ENV{PATH} = "/bin:/usr/bin:/sbin:/usr/sbin";
  @INC = (".", @INC);
}

use POSIX;
use Socket;

use lib qw(.);

#= CONSTANTS      =============================================================

#= GLOB VARIABLES =============================================================
## set defaults
our $g_port=12345;
my $g_maxbuf = 512 ;    ## need to get eventu. from config

#= SUBROUTINES ================================================================

###############################################################################
# SUB:
# PURPOSE:
#
# ARGS:
#
# NOTES:
# RETURNS:
###############################################################################
sub REAPER
{
  my ($childpid,$ex);
  while (($childpid = waitpid(-1,WNOHANG) ) > 0 ) {
    $ex = $?;
    if( $ex ) {
      $ex = $ex/256;
    }
    if( $childpid == -1 ) {
      printf( "reaped a child's system command\n" );
    }
    else {
      printf( "PID $childpid: " . ($ex ? " (exit $ex)." : '.')."\n" );
    }
  }
  $SIG{CHLD} = \&REAPER;
  return;
}

###############################################################################
# SUB:   SysWrite
# PURPOSE: systemwrite
#
# ARGS:
#
# NOTES:
# RETURNS:
###############################################################################
sub SysWrite
{
  my $res=$_[0] ;
  my $buf="" ;
  my $nr = 0 ;

  syswrite( Client, $res, $g_maxbuf) ;
  $res = 0 ;
  eval {
      local $SIG{ALRM} = sub { die "alarm\n" };       # NB \n required
      alarm 120 ;
      $nr = sysread( Client, $buf, $g_maxbuf );
      alarm 0 ;
     };
  die if $@ && $@ ne "alarm\n";       # propagate errors
    if ($@) {
      alarm 0;
      printf( "sysread time out , will be closed\n" );
      $res=6 ;
    }
  if( $nr <= 0 ) {
    if($res != 6 ) {
      $res = 5 ;
    }
  }
  else {
    if(!($buf eq "act" )) {
      $res = 1 ;
    }
  }
  return($res) ;
}

#= MAIN Section begins ========================================================

my( $proto, $pid, $paddr, $port, $iaddr, $name );

$proto = getprotobyname( 'tcp' );
socket( Server, PF_INET, SOCK_STREAM, $proto ) or printf( "socket: $!\n" );
setsockopt( Server, SOL_SOCKET, SO_REUSEADDR, pack("l", 1) ) or printf( "setsockopt: $!\n" );
bind( Server, sockaddr_in($g_port, INADDR_ANY) ) or printf( "bind: $!\n" );
listen( Server, SOMAXCONN ) or printf( "listen: $!\n" );

# set flushing
$| = 1;

$SIG{CHLD} = \&REAPER;

while( 1 ) {
  printf( "Ready to accept connection from client\n" );
  if ( -f "/tmp/stoptest" ) {
    last;
  }
  $paddr = accept( Client, Server );
  if( defined($paddr) ) {
    ($port,$iaddr) = sockaddr_in( $paddr );
    $name = gethostbyaddr( $iaddr, AF_INET );
    printf( "Connection from $name [".inet_ntoa($iaddr)."] at port $port\n" );
    $pid = getpid();
    syswrite( Client, "I'm main process $pid,I've got you connected, how are you! \n", $g_maxbuf) ;
    if( !defined($pid = fork) ) {
      printf( "Cannot fork: $!\n" );
    }
    elsif( $pid ) {
      printf( "New server started with PID: $pid, will be recycled after it's reap\n" );
      $pid = getpid();
      syswrite( Client, "parent feedback PID $pid,I've passed your connection to a child worker process, I'm closing connection.. bye bye!\n", $g_maxbuf) ;
      close Client ;
      sleep(0.1);
    }
    else {    # else I'm the worker child
      $pid = getpid();
      printf( "I'm child worker $pid, I'm trying to do something here for client!, please wait !\n" ) ;
      syswrite( Client, "I'm child worker $pid, trying to do something here for you, please wait !\n", $g_maxbuf) ;
      sleep 5;
      # do real stuff here
      syswrite( Client, "child worker $pid feedback, I'm closing connection.. bye bye!\n", $g_maxbuf) ;
      close Client ;
      exit 44;
    }
  }
  else {
     printf("message from pid $pid,see you !\n");
  }
  printf("here is after child,after sleep secs\n");
  my $current_pid = getpid();
  printf( "tracking main process $pid,$current_pid\n" ) ;
}
printf( "NOTE! daemon stopped! \n" ) ;
exit ( 0 ) ;

__END__