#!/usr/bin/perl
#named muss laufen; localhost (zone 127.0.0.0) wird nicht bearbeitet,
#da konstant. named\.(boot|conf) liegt als Beispiel bei.

#const
#$pz="/var/named/pz" ;
#$hostsfile="/etc/hosts" ;
$pz="/raid/tmp/pz" ;
$hostsfile="/raid/tmp/hosts.yp" ;
#in Hosts: nur einmal IP (am Zeilenanfang, nicht doppelt)
#erste Eintrag ist Realname, rest: CNAME

#forward:
sub dnsheader;
sub getmtime;

#vars:
#$IP = IP - Nummer
#$NAMES = namen aus $hostsfile
#%HOSTS = {$IP}=$NAMES
#@PREREC = $NAMES als Liste (tmp)
#@NAMESREC = $NAMES formatiert, ohne doppelte
#%DNS = {$IP}=@REC , RECS: A, CNAME, CNAME,...

#first check time-stamps:
exit if ((&getmtime("$hostsfile") < &getmtime("$pz/tfh-berlin.de")) and
         (&getmtime("$hostsfile") < &getmtime("$pz/64.141.in-addr.arpa"))); 

open (HOSTS,$hostsfile);

while (<HOSTS>) {
  next if ! /^141\.64\./ ;           #nur tfh-domain
  if (/^(141\.64\.\d+\.\d+)\s+(.+)$/) {
    my $IP = $1;                     #IP - Nummer
    my $NAMES = $2;                  #Namen aus .../hosts
    $NAMES =~ s/\.tfh-berlin\.de//g; #domain raus
    $NAMES =~ s/\s+/ /g;             #space fuer whitespaces
    $NAMES =~ s/\s+$//;              #aber nicht am ende            
    die "IP($IP) mehrfach!!\n" if defined $HOSTS{$IP}; #hamma schon
    $HOSTS{$IP} = $NAMES;            #ansonsten merken
  } else {
    die "IP-Parse-Fehler!\n";        #keine richtige IP-Nummer
  }
}
close (HOSTS);
#Now let's built the %DNS Table
while (($IP,$NAMES) = each %HOSTS) {
  my @PREREC;                        #Namenliste unbearbeitet
  my @NAMESREC;                      #Namenliste: 1. realname rest:CNAME
  @PREREC = split (" ", $NAMES);     #space = delimiter, also " host "
  foreach $NAME (@PREREC) {
    my $nametemp = " " . join(' ',@NAMESREC) . " ";
    if ($nametemp !~ / $NAME /) {    #noch nicht in @NAMESREC? 
      push (@NAMESREC,$NAME);        #dann rein damit!
    }
  }
  $DNS{$IP} = join(' ',@NAMESREC);   #@NAMESREC enthaelt keine doppelten mehr
}
open (STDOUT, ">$pz/tfh-berlin.de") 
     or die "Couldn't create: $pz/tfh-berlin.de\n";
#Now lets export our table
print ";Zone: .tfh-berlin.de.";
&dnsheader;
while (($IP,$DNSREC) = each %DNS) {
  @NAMESREC = split (" ", $DNSREC);  #space = delimiter, also " host "
  printf "%-20s A     %-20s\n",$NAMESREC[0],$IP; #erster ist A:
  foreach $NAME (@NAMESREC[1..$#NAMESREC]) {
    printf "%-20s CNAME %-20s\n",$NAME,$NAMESREC[0]; #rest ist CNAME:
  } 
}
close (STDOUT);
#Reverse Lookup zone file:
open (STDOUT, ">$pz/64.141.in-addr.arpa") 
     or die "Couldn't create: $pz/64.141.in-addr.arpa\n";
print ";Zone: 64.141.in-addr.arpa (for tfh-berlin.de)\n";
&dnsheader;
while (($IP,$DNSREC) = each %DNS) {
  @NAMESREC = split (" ", $DNSREC);  #space = delimiter, also " host "
  $REVIP = $IP;
  $REVIP =~ s/^141\.64\.//;
  $REVIP =~ s/(\d+)\.(\d+)/$2.$1/;
  printf "%-20s PTR   %20s.tfh-berlin.de.\n",$REVIP,$NAMESREC[0]; #erster ist A:
  $IP="";
}
close (STDOUT);

print `killall -v -HUP named`;

die "Zone files updated.\n";



#Bodies der subs:

sub getmtime {
    local($filename) = pop(@_);       
  if (-r $filename) {
  ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = stat ($filename);
  } else { 
    return 1;
  }
  return $mtime;
}


sub dnsheader {
  $now = `date +%Y:%m:%d:%T`;
  $now = join("",split("[/:]",$now));
  chop($now);
  print <<EOF;
;Start Of Authority for private DNS - Server
@        IN      SOA     lnx40.tfh-berlin.de. root.lnx40.tfh-berlin.de. (
                              $now    ; Serial
                              28800   ; Refresh
                              7200    ; Retry
                              604800  ; Expire
                              86400)  ; Minimum TTL
                      NS      lnx40.tfh-berlin.de.
EOF
  return 1;
}