NAME
    POE::Component::Client::DNSBL - A component that provides non-blocking
    DNSBL lookups

VERSION
    version 1.08

SYNOPSIS
      use strict;
      use POE qw(Component::Client::DNSBL);

      die "Please provide at least one IP address to lookup\n" unless scalar @ARGV;

      my $dnsbl = POE::Component::Client::DNSBL->spawn();

      POE::Session->create(
            package_states => [
                'main' => [ qw(_start _stop _response) ],
            ],
            heap => {
                      addresses => [ @ARGV ],
                      dnsbl => $dnsbl
            },
      );

      $poe_kernel->run();
      exit 0;

      sub _start {
         my ($kernel,$heap) = @_[KERNEL,HEAP];
         $heap->{dnsbl}->lookup(
            event => '_response',
            address => $_,
         ) for @{ $heap->{addresses} };
         return;
      }

      sub _stop {
         my ($kernel,$heap) = @_[KERNEL,HEAP];
         $kernel->call( $heap->{dnsbl}->session_id(), 'shutdown' );
         return;
      }

      sub _response {
         my ($kernel,$heap,$record) = @_[KERNEL,HEAP,ARG0];
         if ( $record->{error} ) {
            print "An error occurred, ", $record->{error}, "\n";
            return;
         }
         if ( $record->{response} eq 'NXDOMAIN' ) {
            print $record->{address}, " is okay\n";
            return;
         }
         print join( " ", $record->{address}, $record->{response}, $record->{reason} ), "\n";
         return;
      }

DESCRIPTION
    POE::Component::Client::DNSBL is a POE component that provides
    non-blocking DNS blacklist lookups to other components and POE sessions.
    It uses POE::Component::Client::DNS to perform the requested queries.

    Only IPv4 lookups and URI/RHS lookups are supported and unless a DNSBL
    zone is specified the component will use zen.spamhaus.org.

CONSTRUCTOR
    "spawn"
        Takes a number of parameters:

          'alias', set an alias that you can use to address the component later;
          'options', a hashref of POE session options;
          'dnsbl', the DNSBL zone to send queries to, default zen.spamhaus.org;
          'resolver', optionally provide a POE::Component::Client::DNS to use;

        Returns an object.

METHODS
    "session_id"
        Takes no arguments. Returns the ID of the component's session.

    "shutdown"
        Terminates the component.

    "lookup"
        Performs a DNSBL lookup. Takes a number of parameters:

          'event', the name of the event to send the reply to. ( Mandatory );
          'address', the IPv4 address or domain to lookup ( Mandatory );
          'session', send the resultant event to an alternative session, ( default is the sender );

        You may also pass arbitary key/values. Arbitary keys should have an
        underscore prefix '_'.

        "event" may also be a POE::Session postback.

INPUT EVENTS
    "shutdown"
        Terminates the component.

    "lookup"
        Performs a DNSBL lookup. Takes a number of parameters:

          'event', the name of the event to send the reply to. ( Mandatory );
          'address', the IPv4 address or domain to lookup ( Mandatory );
          'session', send the resultant event to an alternative session, ( default is the sender );
          'dnsbl', optionally override the configured DNSBL for this particular lookup;

        You may also pass arbitary key/values. Arbitary keys should have an
        underscore prefix '_'.

        "event" may also be a POE::Session postback.

OUTPUT EVENTS
    The component will send an event in response to "lookup" requests.
    "ARG0" will be a hashref containing the key/values of the original
    request ( including any arbitary key/values passed ).

    If a POE::Session postback was specified, then the hashref will be the
    first parameter of the arrayref given as "ARG1"

      'response', the status returned by the DNSBL, it will be NXDOMAIN if the address given was okay;
      'reason', if an address is blacklisted, this may contain the reason;
      'error', if something goes wrong with the DNS lookup the error string will be contained here;
      'dnsbl', the DNSBL that was used for this request;

AUTHOR
    Chris "BinGOs" Williams <chris@bingosnet.co.uk>

LICENSE
    Copyright © Chris Williamss.

    This module may be used, modified, and distributed under the same terms
    as Perl itself. Please see the license that came with your Perl
    distribution for details.

SEE ALSO
    <http://en.wikipedia.org/wiki/DNSBL>

    <http://www.spamhaus.org/zen/>

    <http://www.spamhaus.org/dbl/>

    POE

    POE::Session

    POE::Component::Client::DNS

AUTHOR
    Chris Williams <chris@bingosnet.co.uk>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2011 by Chris Williams.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.