#!/usr/bin/perl -w
#
#   dns-update - manage DNS zone files under CVS
#   Copyright (C) 1999  Tommi Virtanen <tv@havoc.fi>
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; either version 2 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#

use strict;
use vars qw($BASEDIR $FROM $PRIMARY $RUNAFTER $TO %SOA_DEFAULTS);
use File::Find;
use POSIX qw(strftime);
use Digest::MD5;

sub fail(@) { die "$0: @_\n" }

do '/etc/dns-update.conf' or fail "config error; $@\n";
chdir($FROM) or fail "Cannot chdir to $FROM: $!";
system('/usr/bin/cvs', '-q', 'update', '-Pd') == 0
  or fail "CVS update failed: $!";
open PRIMARY, "> $PRIMARY.tmp"
  or fail "Cannot open $PRIMARY.tmp for writing: $!";
print PRIMARY "// This file is auto-generated. Do not edit!\n"
  or fail "Cannot write to $PRIMARY.tmp: $!";
find(\&wanted, '.');
close PRIMARY or fail "Closing $PRIMARY.tmp failed: $!";
rename "$PRIMARY.tmp", $PRIMARY
  or fail "Renaming $PRIMARY.tmp to $PRIMARY failed: $!";

if (defined $RUNAFTER and $RUNAFTER ne '') {
  exec $RUNAFTER or fail "Executing post-run commands failed: $!";
}
exit(0);

sub wanted {
  return if $File::Find::dir =~ m{/CVS/};
  return unless -f $_;
  return unless /\.domain$/;
  
  my $file = $File::Find::name;
  $file =~ s{^\./}{};
  $file =~ s{\.domain$}{};
  my $zone = join '.', reverse split '/', $file;
  my $tofile = "$TO/$file.dom";
  -d "$TO/$File::Find::dir" or mkdir "$TO/$File::Find::dir", 0755
    or fail "Cannot create directory $TO/$File::Find::dir";
  convert($zone, "$FROM/$file.domain", $tofile);
  print PRIMARY <<EOF

zone "$zone" {
	type master;
	file "$tofile";
};
EOF
};

sub today() {
  return strftime "%Y%m%d", localtime();
}

sub newserial($;) {
  my ($file) = @_;
  my $serial;
  if (-f $file) {
    open SERIAL, "< $file" 
      or fail "Cannot open $file for reading: $!";
    $serial = <SERIAL>;
    defined $serial or fail "Cannot read serial $file: $!";
    close SERIAL;
    chomp $serial;
    # Here's a Y3K problem:		( ;) )
    my ($d,$n) = ($serial =~ /^([12][0-9][0-9][0-9]		# year
                                (?:0[1-9]|1[0-2])		# month
                                (?:0[1-9]|[12][0-9]|3[01]))	# day
                                ([0-9][0-9])			# serial
                  $/x);
    defined $d and defined $n or fail "Invalid serial: $file is $serial";
    if ($d eq today()) {
      $n++;
      $n<100 or fail "Too big serial in $file";
      $serial = $d . $n;
    }
    else { $serial = today() . '01' }
  }
  else { $serial = today() . '01' }
  open SERIAL, "> $file" or fail "Cannot open $file for reading: $!";
  print SERIAL "$serial\n" or fail "Cannot write to $file: $!";
  close SERIAL or fail "Closing $file failed: $!";
  return $serial;
}

sub md5_modified($*) {
  my ($sumfile, $fh) = @_;
  my $oldsum;
  if (-e $sumfile) {
    open OLD, "< $sumfile" or fail "Cannot open $sumfile for reading: $!";
    $oldsum = <OLD>;
    close OLD;
    defined $oldsum or fail "No md5sum read from file $sumfile";
    chomp $oldsum;
    $oldsum =~ /^[0-9a-z]{32}$/ or fail "Bad md5sum from file $sumfile";
  } else {
    $oldsum = '';
  }
  my $md5 = new Digest::MD5;
  $md5->addfile($fh);
  seek($fh, 0, 0) or fail "Cannot rewind: $!";
  my $newsum = $md5->hexdigest();
  if ($newsum eq $oldsum) { return 0 }
  else {
    open SUM, "> $sumfile" or fail "Cannot open $sumfile for writing: $!";
    print SUM "$newsum\n" or fail "Cannot write to $sumfile: $!";
    close SUM or fail "Closing $sumfile failed: $!";
    return 1;
  }
}

sub convert($$$;) {
  my ($name, $from, $to) = @_;
  open(IN, "< $from") or fail "Cannot open $from for reading: $!";
  return 0 
    unless md5_modified("$to.md5sum", *IN{IO})
      or grep {$_ eq '-f'} @ARGV;
  
  my $serial = newserial "$to.serial";
  open(OUT, "> $to.tmp") or fail "Cannot open $to.tmp for writing: $!";
  print OUT ";;; This file is auto-generated. Do not edit!\n"
    or fail "Cannot write to $to.tmp: $!";
  local $_;
  while(<IN>) {
    chomp;
    while (s/\\$//) {
      my $tmp=<IN>;
      defined $tmp
        or fail "End of file while combining lines in $name";
      chomp $tmp;
      $_.=$tmp;
    }
    if(s/^!template(?:$|\s+)//i) {
      print OUT template($name, $serial, $_) 
        or fail "Cannot write to $to.tmp: $!";
    }
    else {
      print OUT "$_\n" or fail "Cannot write to $to.tmp: $!";
    }
  }
  close(IN) or fail "Close failed on $from: $!";
  close(OUT) or fail "Close failed on $to.tmp: $!";
  rename("$to.tmp", "$to") or "Rename $to.tmp to $to failed: $!";
}

sub template($$$;) {
  my ($name, $serial, $opts) = @_;
  my %vars=%::SOA_DEFAULTS;
  my %allowed_opts=(origin=>`hostname -f`); #TODO *barf* *puke*

  foreach (split ' ',$opts) {
    s/^([a-z]+)=//
      or fail "Invalid options to !template in $name.domain";
    exists $vars{lc $1} or exists $allowed_opts{lc $1}
      or fail "Invalid option $1 to !template in $name.domain";
    $vars{lc $1}=$_;    
  }
  return <<EOF
\$TTL	$vars{minttl}	; time to live
@	IN	SOA	$vars{origin}. $vars{hostmaster}. (
	$serial	; serial number
	$vars{refresh}	; refresh
	$vars{retry}	; retry
	$vars{expire}	; expire
	$vars{negttl} )	; negative cache time-to-live
EOF
}

__END__

=head1 NAME

dns-update - manage DNS zone files under CVS

=head1 SYNOPSIS

dns-update [options]

=head1 DESCRIPTION

TODO write a description

=head1 OPTIONS

  -f	Force regeneration even if the zone has not changed.

=head1 BUGS

This manpage.

=head1 AUTHOR

Tommi Virtanen <tv@havoc.fi>

=cut