NAME
    URPL::Prepare -- prepare hostname for URBL domain lookup

SYNOPSIS
      require URBL::Prepare;

      my $ubp = new URBL::Prepare;

      $tlds = $blessed->cachetlds($localfilelistptr);
      $whitelist = $blessed->cachewhite($localfilelistptr);
      $domain = $blessed->urbldomain($hostname)
      $response_code = $proto->loadcache($url,$localfile);
      ($response,$message) = $proto->loadcache($url,$localfile);

DESCRIPTION
    * my $urbl = new URBL::Prepare;
    This method returns a blessed reference to an empty hash.

    For use with other modules:

      require URBL::Prepare;

      @ISA = qw(URBL::Prepare);

URBL Preparation for lookup methods
    The following three methods are for facilitating URBL lookups.

      SEE:  http://www.uribl.com/about.shtml
      and   http://www.surbl.org/guidelines

    * $tldlist = $blessed->cachetlds($localfilelistptr);
    This method opens local files in "file list" and extracts the tld's
    found therein.

      input:        ptr to array of local/file/path/names
      return:       array ptr to list of tld's

    NOTE: place level 3 tld's ahead of level 2 tld's

    * $whitelist = $blessed->cachewhite($localfilelistptr);
    This method opens local file(s) in "file list" and extracts the domains
    found therein.

      See http://wiki.apache.org/spamassassin/DnsBlocklists         and
      http://spamassasin.googlecode.com/svn-history/r6/trunk/share/spamassassin/

    Note:: these URL's may change

      input:        ptr to array of local/file/path/names
      return:       array ptr to whitelist domain names

    * $domain = $blessed->urbldomain($hostname)
    This method extracts a domain name to check against an SURBL. If the
    hostname is whitelisted, the return value is false, otherwise a domain
    name is returned.

      input:        hostname
      return:       false if whitelited,
             else   domain name

    NOTE: optionally white or tld testing will be bypassed if the pointer is
    undefined or points to an empty array.

    * $response_code = $proto->loadcache($url,$localfile);
    * ($response,$message) = $proto->loadcache($url,$localfile);
    This method uses LWP::UserAgent::mirror to conditionally retrieve files
    to fill local cache with WHITELIST and TLD names. The response code is
    the result returned by the HTTP fetch and should be one of 200 or 304.
    At the time this module was released the files were as follows:

      WHITE LIST URL
      http://spamassasin.googlecode.com/svn-history/r6/trunk/share/spamassassin/25_uribl.cf

    and

      TLDLIST URL (include some known abusive tlds)
      http://george.surbl.org/three-level-tlds
      http://george.surbl.org/two-level-tlds

      input:        path/name/for/localfile
      return:       http response code,
                    response message

    In scalar context only the http response code is returned. In array
    context the numeric response code and a related text message are
    returned.

      200   OK              file cached
      304   Not Modified    file is up-to-date

    Any other response code indicates and error.

      Usage:
      $rv = URBL::Prepare->loadcache($url,$localfile);

APPLICATION EXAMPLES
    This example shows how to include URBL::Prepare in another module

      #!/usr/bin/perl
      package = Some::Package

      use vars qw(@ISA);
      require URBL::Prepare;

      @ISA = qw( URBL::Prepare );

      sub new {
        my $proto = shift;
        my $class = ref $proto || $proto || __PACKAGE__;
        my $methodptr = {
            ....
        };
        bless $methodptr, $class;
      }
      ... package code ...
      1;

      ...end
    ......................

      #!/usr/bin/perl
      # my application
      #
      use Net::DNS::Dig;
      use Some::Package;

      my $dig = new Net::DNS::Dig;
      my $sp = new Some::Package;
      #
      # initialiaze URBL::Prepare
      #
      $sp->cachewhite($localwhitefiles);
      $sp->cachetlds($localtldfiles);

      # set multisurbl.org bit mask
      #     2 = comes from SC
      #     4 = comes from WS
      #     8 = comes from PH
      #     16 = comes from OB (OB is deprecated as of 22 October 2012.)
      #     16 = comes from MW (MW active as of 1 May 2013.)
      #     32 = comes from AB
      #     64 = comes from JP

      my $mask = 0xDF;

        ... application ...
        ... generates   ...
        ... hostname    ...

      my $domain = $sp->urbldomain($hostname)

      # the procedure for using black.uribl.com is the same
      my $response = $dig->for($hostname . 'multi.surbl.org')
            if $domain;     # if not whitelisted

      # if an answer is returned
      if ($domain && $response->{HEADER}->{ANCOUNT}) {
        # get packed ipV4 answer
        my $answer = $response->{ANSWER}->[0]->{RDATA}->[0];
        if ($mask & unpack("N",$answer)) {
            # answer is found in selected surbl list
        } else {
            # answer not found in selected surbl list
        }
      }
      # domain not found in surbl

      ...end

    This is an example of a script file to keep the whitelist and tldlist
    current. Run as a cron job daily.

      #!/usr/bin/perl
      #
      # cache refresh cron job
      #
      require URBL::Prepare;

      my $whitefile =
      'http://spamassasin.googlecode.com/svn-history/r6/trunk/share/spamassassin/25_uribl.cf';

      my $tldfile2 = 'http://george.surbl.org/two-level-tlds';
      my $tldfile3 = 'http://george.surbl.org/three-level-tlds';

      my $cachedir  = './cache';
      my $level2    = $cachedir .'/level2';
      my $level3    = $cachedir .'/level3';
      my $white     = $cachedir .'/white';

      mkdir $cachedir unless -d $cachedir;

      URBL::Prepare->loadcache($whitefile,$white);
      URBL::Prepare->loadcache($tldfile2,$level2);
      URBL::Prepare->loadcache($tldfile3,$level3);

AUTHOR
    Michael Robinton <michael@bizsystems.com>

COPYRIGHT
        Copyright 2013, Michael Robinton <michael@bizsystems.com>

    This program is free software; you may redistribute it and/or modify it
    under the same terms as Perl itself.

    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 also:
    the LWP::Request manpage, the Net::DNS::Dig manpage

