#!/usr/bin/perl

#   
#
# Creation Date: 21st July 2003
#
#       Author:
#       Peter P. McGarvey <xaphod@techie.com>
#       
#       Additional Code:
#       Evren Yurtesen <yurtesen@ispro.net.tr>
#
# VERSION HISTORY                            
#                
#       format x.y.z
#               - x = Major version number
#               - y = Minior version number           
#               - z = Burst number                    
#                       I work in bursts.  Weekend here, couple of hours a night
#                       there, then a night (a week etc.) off to think.  The
#                       `burst number' helps me keep track of different versions
#                       methinks CVS would be a good idea one day.
#                                                     
#    0.0.1  2003-07-21  - Peter P. McGarvey <xaphod@techie.com>
#			  * A NASTY hack of a perl script.
#    0.1.1  2003-07-22  - Evren Yurtesen <yurtesen@ispro.net.tr>
#                         * Added named.conf file parsing
#                         * Added automatical nameserver checking
#                                                     
use vars qw($VERSION);                                
$VERSION = '0.1.1';                                   
#                                                     
# =============================================================================

#location of named.conf file
$named_conf="named.conf";

#the name servers you expect to see
@nameservers=('ns1.ispro.net','ns2.ispro.net','dns1.ispro.net.tr','dns2.ispro.net.tr');

#debugging level (the higher, the more text!)
$debug=20;

# =============================================================================
# Starting the Code


use Net::DNS;         
                     

my $timeout=0;

my @domainlist = &get_domain_list;

foreach my $zone (&get_domain_list) {
#while(my $zone = <domainlist>) {
  print "# zone: $zone\n";
  my ($parent_zone) = $zone =~ /^[^\.]*\.(.*)/;
  print "# parent of $zone is $parent_zone\n";
  my $parent_auth_primary = &get_auth_primary($parent_zone, $timeout);
  if ($parent_auth_primary == -1) {    
    print "# DEAD ZONE!\n# ABORT\n\n";
    print DEAD "# $zone\n";          
    next;
  }
  print "# parent auth primary is: $parent_auth_primary\n";
  my @auth_servers = &get_ns_list($zone, $parent_auth_primary, $timeout);
  if (scalar(@auth_servers) == 0) {               
    print "# No auth servers, DEAD ZONE!\n";
    print DEAD "$zone\n";
    next;      
  }
  foreach my $ns (@auth_servers) {
    $ns = lc($ns);
    print $ns, "\n";         
  }
}

# =============================================================================
# End of the Code	- Start of the Sub-Functions
# &get_domain_list	- Returns the list of domains from named.conf.file
# &get_auth_primary	- Takes the name of a zone               
#			  Return the MNAME field from the SOA
# &get_ns_list		- Returns the list of NS records reported by that server

# =============================================================================
# Returns the list of domains from named.conf file
sub get_domain_list {
  open(NAMED_CONF,"< $named_conf") or die "Can not open $named_conf";
  #set some variables to 0
  $comment_block_starting=0;
  $comment_block_started=0;
  #make a list of domains
  while($line=<NAMED_CONF>) {
    #find if there is double backslash and use only left of it
    #we must put newline
    if($line =~ /\/\//) {
      $line=(split /\/\//,$line)[0]."\n";
    }
    #find if there is both /* my text */ in $line and use only outside 
    if ($line =~ /\/\*/ && $line =~ /\*\//) {
       @values1=split(/\/\*/,$line);
       @values2=split(/\*\//,$line);
       $line=$values1[0].$values2[1];
    } else { #find if there is only one of them?
      #if there is only /* take left side and wait until finding */
      if($line =~ /\/\*/) {
        $line=(split /\/\*/,$line)[0];
        #count the occurances in case if they are nested
        $comment_block_starting+=1;
      }
      #if there is only */ then stop waiting and take right side
      if($line =~ /\*\//) {
        $line=(split /\*\//,$line)[1];
        if(($comment_block_starting-=1) eq 0) {
          $comment_block_started=0;
        }
      }
    }
    if (($comment_block_started=$comment_block_starting) eq 0) {
      if($line =~ /zone.+\".+\"/ && ! ($line =~ /zone.+\"."/ || $line =~ /zone.+\".*ARPA\"/i)) {
        $line=(split /\"/,$line)[1];
        #cut out left and right spaces just to be sure
        $line =~ s/^\s+|\s+$//g;
        push(@domainlist,$line);
      }
    }
  }
  close(NAMED_CONF);
  return sort @domainlist;
}

# =============================================================================
# Takes the name of a zone
# Return the MNAME field from the SOA
sub get_auth_primary {
    my $zone = shift;
    my $tcp_timeout = shift;
    
    my $res = new Net::DNS::Resolver;
    my $packet = new Net::DNS::Packet($zone, "SOA", "IN");
        
    $res->tcp_timeout($tcp_timeout) if $tcp_timeout;

    my $req = $res->send($packet);

    return -1
        unless defined($req);
    return -1
        unless ( ($req->header->ancount >= 1)
              && (($req->answer)[0]->type eq "SOA") );
    return ($req->answer)[0]->mname . ".";
            # Return the FQDN
}

# =============================================================================
# Returns the list of NS records reported by that server
sub get_ns_list {
    my $zone = shift;            
    my $server = shift;
    my $tcp_timeout = shift;
 
    my @ns_list;
                          
    my $res = new Net::DNS::Resolver;
         
    $res->tcp_timeout($tcp_timeout) if $tcp_timeout;
       
    #die "FAIL: NS has no address (" . $res->errorstring . ")"                 
    return @ns_list       
         unless $res->nameservers($server);

    my $req = $res->query($zone, "NS");
    
    #die "WARN: NS query results were bad (" . $res->errorstring . ")"
    return @ns_list                  
           unless ( defined($req)
                 && ($req->header->ancount > 0) );
    
    foreach my $rr_ns ($req->answer) {
        push @ns_list, $rr_ns->nsdname . "."; #FQDN!
    }
    return sort @ns_list;
}