#!/usr/bin/env perl

# Public domain.

# Like any other piece of software (and information generally), this script
# comes with NO WARRANTY.

# This is version 20191009 of openbsd-release-version.pl.

use strict;
use warnings FATAL => 'all';

use Net::DNS;
use Time::Piece;
use Time::Seconds;
use Time::Local;

use constant EPOCH => timegm(0,0,12,17,10,1858); # MJD

my $response = undef;
my $rr       = undef;
my $ch       = -1;
my $len      = -1;
my $dns      = Net::DNS::Resolver->new(
  recurse => 1,
  debug   => 0,
);

my $tp = Time::Piece->new(EPOCH);
my $h  = undef;
my $j  = 4;
my $v  = 2;

eval {
  $response = $dns->query( 'openbsdversion.bze.ro', 'TXT' );
};

if    ($@)                                    { die($!); }
if    (!defined($response))                   { die('no response'); }
elsif ('NOERROR' ne $response->header->rcode) { die('error in response'); }
elsif (1 != scalar($response->answer))        { die('incorrect number of answers received'); }

eval {
  $rr = ($response->answer)[0];
};

if ($@)                 { die($!); }
if (!defined($rr))      { die('empty response'); }
if ('TXT' ne $rr->type) { die('incorrect resource record answer type'); }

$len = length($rr->txtdata) - 1;
if (1 > $len) { die('response length not long enough'); }
$ch = unpack("x$len A", $rr->txtdata);
if (',' ne $ch) { die('corrupt response received'); }

$ch = index($rr->txtdata, ':');
if (0 > $ch) { die('corrupt response received'); }

$len = unpack("A$ch", $rr->txtdata);
$len += $ch;
$ch++;

while ($ch < $len) {
  $h   = hex unpack("x$ch A$j", $rr->txtdata);
  $tp += ONE_DAY * $h;
  print $tp->ymd, sprintf(" %0.1f", $v), "\n";

  $ch += $j;
  $j  = 2;
  $v += 0.1;
}
exit(0);
# END