NAME

POE::Component::Server::DNS - A non-blocking, concurrent DNS server POE component

VERSION

version 0.32

SYNOPSIS

  use strict;
  use Net::DNS::RR;
  use POE qw(Component::Server::DNS);

  my $dns_server = POE::Component::Server::DNS->spawn( alias => 'dns_server' );

  POE::Session->create(
        package_states => [ 'main' => [ qw(_start handler log) ], ],
  );

  $poe_kernel->run();
  exit 0;

  sub _start {
    my ($kernel,$heap) = @_[KERNEL,HEAP];

    # Tell the component that we want log events to go to 'log'
    $kernel->post( 'dns_server', 'log_event', 'log' );

    # register a handler for any foobar.com suffixed domains
    $kernel->post( 'dns_server', 'add_handler',
        {
          event => 'handler',
          label => 'foobar',
          match => 'foobar\.com$',
        }
    );
    undef;
  }

  sub handler {
    my ($qname,$qclass,$qtype,$callback) = @_[ARG0..ARG3];
    my ($rcode, @ans, @auth, @add);

    if ($qtype eq "A") {
      my ($ttl, $rdata) = (3600, "10.1.2.3");
      push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
      $rcode = "NOERROR";
    } else {
      $rcode = "NXDOMAIN";
    }

    $callback->($rcode, \@ans, \@auth, \@add, { aa => 1 });
    undef;
  }

  sub log {
    my ($ip_port,$net_dns_packet) = @_[ARG0..ARG1];
    $net_dns_packet->print();
    undef;
  }

DESCRIPTION

POE::Component::Server::DNS is a POE component that implements a DNS server.

It uses POE::Component::Client::DNS to handle resolving when configured as 'forward_only' and Net::DNS::Resolver::Recurse wrapped by POE::Component::Generic to perform recursion.

One may add handlers to massage and manipulate responses to particular queries which is vaguely modelled after Net::DNS::Nameserver.

CONSTRUCTOR

spawn

Starts a POE::Component::Server::DNS component session and returns an object. Takes a number of optional arguments:

  "alias", an alias to address the component by;
  "port", which udp port to listen on. Default is 53, which requires 'root' privilege on UN*X type systems;
  "address", which local IP address to listen on.  Default is INADDR_ANY;
  "resolver_opts", a set of options to pass to the POE::Component::Client::DNS constructor;
  "forward_only", be a forwarding only DNS server. Default is 0, be recursive.
  "no_clients", do not spawn client code (See following notes);

"no_clients" disables the spawning of client code (PoCo::Client::DNS, Net::DNS::Resolver::Recursive), and doesn't attempt to forward or recurse inbound requests. Any request not handled by one of your handlers will be "REFUSED". Saves some resources when you intend your server to be authoritative only (as opposed to a general resolver for DNS client software to point at directly). Additionally, this argument changes the default "Recursion Available" flag in responses to off instead of on.

METHODS

These are methods that may be used with the object returned by spawn().

session_id: Returns the POE::Session ID of the component's session.
resolver: Returns a reference to the POE::Component::Client::DNS object.
shutdown: Terminates the component and associated resolver.
sockport: Returns the port of the socket that the component is listening on.

INPUT EVENTS

These are states that the component will accept:

add_handler

Accepts a hashref as an argument with the following keys:

  "event", the event the component will post to, mandatory;
  "label", a unique name for this handler, mandatory;
  "match", a regex expression ( without // ) to match against the host part of queries, mandatory;
  "session", the session where this handler event should be sent to, defaults to SENDER;

See OUTPUT EVENTS for details of what happens when a handler is triggered.

del_handler

Accepts a handler label to remove.

log_event

Tells the component that a session wishes to receive or stop receiving DNS log events. Specify the event you wish to receive log events as the first argument. If no event is specified you stop receiving log events.

shutdown

Terminates the component and associated resolver.

HANDLER EVENTS

These events are triggered by a DNS query matching a handler. The applicable event is fired in the requested session with the following paramters:

  ARG0, query name
  ARG1, query class
  ARG2, query type
  ARG3, a callback coderef
  ARG4, the IP address and port of the requestor, 'IPaddr:port'

Do your manipulating then use the callback to fire the response back to the component, returning a response code and references to the answer, authority, and additional sections of the response. For advanced usage there is an optional argument containing an hashref with the settings for the aa, ra, and ad header bits. The argument is of the form { ad => 1, aa => 0, ra => 1 }.

  $callback->( $rcode, \@ans, \@auth, \@add, { aa => 1 } );

LOG EVENTS

These events are triggered whenever a DNS response is sent to a client.

  ARG0, the IP address and port of the requestor, 'IPaddr:port';
  ARG1, the Net::DNS::Packet object;

See Net::DNS::Packet for details.

HISTORY

The component's genesis was inspired by Jan-Pieter's 'Fun with POE' talk at YAPC::EU 2006, which lay much of the ground-work code such as the POE::Driver and POE::Filter used internally. BinGOs wrapped it all up in a component, added the tests ( borrowed shamelessly from POE::Component::Client::DNS's testsuite ) and documentation.

Other suggestions as to the API were provided by Ben 'integral' Smith.

Rocco Caputo brought POE::Component::Client::DNS to the party.

AUTHORS

Chris Williams <chris@bingosnet.co.uk>
Jan-Pieter Cornet <johnpc@xs4all.nl>
Brandon Black <blblack@gmail.com>
Richard Harman <richard@richardharman.com>
Stephan Jauernick <stephan@stejau.de>

COPYRIGHT AND LICENSE

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