use strict;
use warnings;
use IO::Select;

my $an;
my $timeout = 20;
my $read_set = new IO::Select();

eval {
  local $SIG{ALRM} = sub { die "Timeout\n"; };
  alarm $timeout;

  open my $fh, "tcpdump -nn -l -e dst 224.111.111.112 and not igmp 2>/dev/null |";
  $read_set->add($fh);

  while (1) {
    my ($rh_set) = IO::Select->select($read_set, undef, undef, 1);

    if (defined $rh_set) {
      if ($_ = <$fh>) {;
        if (s/^\S* \S* M \S* \S* 0800 \S*: (\S*\.\S*\.\S*\.\S*)\.\S* > \S*\.\S*:.*$/$1/s) {
          $an = $1;
          alarm 0;
          last;
        }
      } else {
        logwarn "EOF while reading from tcpdump. sleeping 2 seconds and restarting tcpdump";
        $read_set->remove($fh);
        close $fh;
        sleep 2;
        open $fh, "tcpdump -nn -l -e dst 224.111.111.112 and not igmp 2>/dev/null |";
        $read_set->add($fh);
      }
    }
  }
  close $fh;

};

if ($@ && ($@ ne "Timeout\n")) {
  die $@;
}

if (defined $an) {
  print "$an\n";
  exit 0;
} else {
  print "NONE\n";
  exit 1;
}