Class: Dnsruby::Resolver

Classes and Modules

Constants

 DefaultQueryTimeout
 DefaultPacketTimeout
 DefaultRetryTimes
 DefaultRetryDelay
 DefaultPort
 true
 AbsoluteMinDnssecUdpSize
 MinDnssecUdpSize
 MinDnssecUdpSize

Attributes

config	[R]	The current Config
dnssec	[R]	Use DNSSEC for this Resolver
do_caching	[R]	Does this Resolver cache answers, and attempt to retrieve answer from the cache?
do_caching	[RW]	Defines whether we will cache responses, or pass every request to the upstream resolver. This is only really useful when querying authoritative servers (as the upstream recursive resolver is likely to cache)
do_validation	[RW]	Defines whether validation is performed by default on this Resolver when the query method is called. Note that send_message and send_async expect a Message object to be passed in, which is already configured to the callers requirements.
ignore_truncation	[R]	Should truncation be ignored? i.e. the TC bit is ignored and thus the resolver will not requery over TCP if TC is set
no_tcp	[R]	If no_tcp==true, then ONLY UDP will be used as a transport. This should not generally be used, but is provided as a debugging aid.
packet_timeout	[R]	The timeout for any individual packet. This is the timeout used by SingleResolver
port	[R]	The port to send queries to on the resolver
query_timeout	[RW]	Note that this timeout represents the total time a query may run for - multiple packets can be sent to multiple nameservers in this time. This is distinct from the SingleResolver per-packet timeout The query_timeout is not required - it will default to 0, which means "do not use query_timeout". If this is the case then the timeout will be dictated by the retry_times and retry_delay attributes
recurse	[R]	Should the Recursion Desired bit be set?
retry_delay	[RW]	The query will be tried across nameservers retry_times times, with a delay of retry_delay seconds between each retry. The first time round, retry_delay will be divided by the number of nameservers being targetted, and a new nameserver will be queried with the resultant delay.
retry_times	[RW]	The query will be tried across nameservers retry_times times, with a delay of retry_delay seconds between each retry. The first time round, retry_delay will be divided by the number of nameservers being targetted, and a new nameserver will be queried with the resultant delay.
src_address	[R]	The source address to send queries from
tsig	[R]
udp_size	[R]	The maximum UDP size to be used
use_tcp	[R]	Should TCP be used as a transport rather than UDP? If use_tcp==true, then ONLY TCP will be used as a transport.

Public Class methods

check_port(p, src_port=[])

[Source]

     # File lib/Dnsruby/Resolver.rb, line 593
593:     def Resolver.check_port(p, src_port=[])
594:       if (p.class != Fixnum)
595:         tmp_src_ports = Array.new(src_port)
596:         p.each do |x|
597:           if (!Resolver.check_port(x, tmp_src_ports))
598:             return false
599:           end
600:           tmp_src_ports.push(x)
601:         end
602:         return true
603:       end
604:       if (Resolver.port_in_range(p))
605:         if ((p == 0) && (src_port.length > 0))
606:           return false
607:         end
608:         return true
609:       else
610:         Dnsruby.log.error("Illegal port (#{p})")
611:         raise ArgumentError.new("Illegal port #{p}")
612:       end
613:     end

get_ports_from(p)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 625
625:     def Resolver.get_ports_from(p)
626:       a = []
627:       if (p.class == Fixnum)
628:         a = [p]
629:       else
630:         p.each do |x|
631:           a.push(x)
632:         end
633:       end
634:       return a
635:     end

get_tsig(args)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 659
659:     def Resolver.get_tsig(args)
660:       tsig = nil
661:       if (args.length == 1)
662:         if (args[0])
663:           if (args[0].instance_of?RR::TSIG)
664:             tsig = args[0]
665:           elsif (args[0].instance_of?Array)
666:             if (args[0].length > 2)
667:               tsig = RR.new_from_hash({:type => Types.TSIG, :klass => Classes.ANY, :name => args[0][0], :key => args[0][1], :algorithm => args[0][2]})
668:             else
669:               tsig = RR.new_from_hash({:type => Types.TSIG, :klass => Classes.ANY, :name => args[0][0], :key => args[0][1]})
670:             end
671:           end
672:         else
673:           #          Dnsruby.log.debug{"TSIG signing switched off"}

674:           return nil
675:         end
676:       elsif (args.length ==2)
677:         tsig = RR.new_from_hash({:type => Types.TSIG, :klass => Classes.ANY, :name => args[0], :key => args[1]})
678:       elsif (args.length ==3)
679:         tsig = RR.new_from_hash({:type => Types.TSIG, :klass => Classes.ANY, :name => args[0], :key => args[1], :algorithm => args[2]})
680:       else
681:         raise ArgumentError.new("Wrong number of arguments to tsig=")
682:       end
683:       Dnsruby.log.info{"TSIG signing now using #{tsig.name}, key=#{tsig.key}"}
684:       return tsig
685:     end

new(*args)

Create a new Resolver object. If no parameters are passed in, then the default system configuration will be used. Otherwise, a Hash may be passed in with the following optional elements :

:port
:use_tcp
:tsig
:ignore_truncation
:src_address
:src_port
:recurse
:udp_size
:config_info - see Config
:nameserver - can be either a String or an array of Strings
:packet_timeout
:query_timeout
:retry_times
:retry_delay
:do_caching

[Source]

     # File lib/Dnsruby/Resolver.rb, line 373
373:     def initialize(*args)
374:       # @TODO@ Should we allow :namesver to be an RRSet of NS records? Would then need to randomly order them?

375:       @resolver_ruby = nil
376:       @src_address = nil
377:       @single_res_mutex = Mutex.new
378:       @configured = false
379:       @do_caching = true
380:       @config = Config.new()
381:       reset_attributes
382:       
383:       # Process args

384:       if (args.length==1)
385:         if (args[0].class == Hash)
386:           args[0].keys.each do |key|
387:             begin
388:               if (key == :config_info)
389:                 @config.set_config_info(args[0][:config_info])
390:               elsif (key==:nameserver)
391:                 set_config_nameserver(args[0][:nameserver])
392:               elsif (key==:nameservers)
393:                 set_config_nameserver(args[0][:nameservers])
394:               else
395:                 send(key.to_s+"=", args[0][key])
396:               end
397:             rescue Exception
398:               Dnsruby.log.error{"Argument #{key} not valid\n"}
399:             end
400:           end
401:         elsif (args[0].class == String)
402:           set_config_nameserver(args[0])          
403:         elsif (args[0].class == Config)
404:           # also accepts a Config object from Dnsruby::Resolv

405:           @config = args[0]
406:         end
407:       else
408:         # Anything to do?

409:       end
410:       #      if (@single_resolvers==[])

411:       #        add_config_nameservers

412:       #      end

413:       update
414:       #      ResolverRegister::register_resolver(self)

415:     end

port_in_range(p)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 615
615:     def Resolver.port_in_range(p)
616:       if ((p == 0) || ((p >= 50000) && (p <= 65535)))
617:         # @TODO@ IANA port bitmap - use 50000 - 65535 for now

618:         #            ((Iana::IANA_PORTS.index(p)) == nil &&

619:         #              (p > 1024) && (p < 65535)))

620:         return true
621:       end
622:       return false
623:     end

Public Instance methods

add_src_port(p)

Can be a single Fixnum or a Range or an Array If an invalid port is selected (one reserved by IANA), then an ArgumentError will be raised. "0" means "any valid port" - this is only a viable option if it is the only port in the list. An ArgumentError will be raised if "0" is added to an existing set of source ports.

       res.add_src_port(60000)
       res.add_src_port([60001,60005,60010])
       res.add_src_port(60015..60115)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 580
580:     def add_src_port(p)
581:       if (Resolver.check_port(p, @src_port))
582:         a = Resolver.get_ports_from(p)
583:         a.each do |x|
584:           if ((@src_port.length > 0) && (x == 0))
585:             raise ArgumentError.new("src_port of 0 only allowed as only src_port value (currently #{@src_port.length} values")
586:           end
587:           @src_port.push(x)
588:         end
589:       end
590:       update
591:     end

close()

Close the Resolver. Unfinished queries are terminated with OtherResolvError.

[Source]

     # File lib/Dnsruby/Resolver.rb, line 349
349:     def close
350:       @resolver_ruby.close if @resolver_ruby
351:     end

dnssec=(d)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 723
723:     def dnssec=(d)
724:       @dnssec = d
725:       if (d)
726:         # Set the UDP size (RFC 4035 section 4.1)

727:         if (@udp_size < MinDnssecUdpSize)
728:           self.udp_size = MinDnssecUdpSize
729:         end
730:       end
731:       update
732:     end

do_caching=(on)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 713
713:     def do_caching=(on)
714:       @do_caching=on
715:       update
716:     end

ignore_truncation=(on)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 688
688:     def ignore_truncation=(on)
689:       @ignore_truncation = on
690:       update
691:     end

nameserver=(n)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 522
522:     def nameserver=(n)
523:       @configured = true
524:       @single_res_mutex.synchronize {
525:         @single_resolvers=[]
526:       }
527:       set_config_nameserver(n)
528:       add_config_nameservers
529:     end

nameservers=(ns)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 519
519:     def nameservers=(ns)
520:       self.nameserver=(n)
521:     end

no_tcp=(on)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 642
642:     def no_tcp=(on)
643:       @no_tcp=on
644:       update
645:     end

packet_timeout=(t)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 536
536:     def packet_timeout=(t)
537:       @packet_timeout = t
538:       update
539:     end

persistent_tcp=(on)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 703
703:     def persistent_tcp=(on)
704:       @persistent_tcp = on
705:       update
706:     end

persistent_udp=(on)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 708
708:     def persistent_udp=(on)
709:       @persistent_udp = on
710:       update
711:     end

port=(a)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 698
698:     def port=(a)
699:       @port = a
700:       update
701:     end

query(name, type=Types.A, klass=Classes.IN, set_cd=@dnssec)

Query for a name. If a valid Message is received, then it is returned to the caller. Otherwise an exception (a Dnsruby::ResolvError or Dnsruby::ResolvTimeout) is raised.

  require 'Dnsruby'
  res = Dnsruby::Resolver.new
  response = res.query("example.com") # defaults to Types.A, Classes.IN
  response = res.query("example.com", Types.MX)
  response = res.query("208.77.188.166") # IPv4 address so PTR query will be made
  response = res.query("208.77.188.166", Types.PTR)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 170
170:     def query(name, type=Types.A, klass=Classes.IN, set_cd=@dnssec)
171:       msg = Message.new
172:       msg.do_caching = @do_caching
173:       msg.header.rd = 1
174:       msg.add_question(name, type, klass)
175:       msg.do_validation = @do_validation
176:       if (@dnssec)
177:         msg.header.cd = set_cd # We do our own validation by default

178:       end
179:       return send_message(msg)
180:     end

recurse=(a)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 718
718:     def recurse=(a)
719:       @recurse = a
720:       update
721:     end

send_async(*args)

Asynchronously send a Message to the server. The send can be done using just Dnsruby. Support for EventMachine has been deprecated.

Dnsruby pure Ruby event loop :

A client_queue is supplied by the client, along with an optional client_query_id to identify the response. The client_query_id is generated, if not supplied, and returned to the client. When the response is known, a tuple of (query_id, response_message, exception) will be added to the client_queue.

The query is sent synchronously in the caller‘s thread. The select thread is then used to listen for and process the response (up to pushing it to the client_queue). The client thread is then used to retrieve the response and deal with it.

Takes :

msg - the message to send
client_queue - a Queue to push the response to, when it arrives
client_query_id - an optional ID to identify the query to the client
use_tcp - whether to use only TCP (defaults to SingleResolver.use_tcp)

Returns :

client_query_id - to identify the query response to the client. This ID is

generated if it is not passed in by the client

Example invocations :

    id = res.send_async(msg, queue)
    NOT SUPPORTED : id = res.send_async(msg, queue, use_tcp)
    id = res.send_async(msg, queue, id)
    id = res.send_async(msg, queue, id, use_tcp)

Example code :

   require 'Dnsruby'
   res = Dnsruby::Resolver.newsend
   query_id = 10 # can be any object you like
   query_queue = Queue.new
   res.send_async(Message.new("example.com", Types.MX),  query_queue, query_id)
   query_id_2 = res.send_async(Message.new("example.com", Types.A), query_queue)
   # ...do a load of other stuff here...
   2.times do
     response_id, response, exception = query_queue.pop
     # You can check the ID to see which query has been answered
     if (exception == nil)
         # deal with good response
     else
         # deal with problem
     end
   end

[Source]

     # File lib/Dnsruby/Resolver.rb, line 329
329:     def send_async(*args) # msg, client_queue, client_query_id)

330:       if (!@configured)
331:         add_config_nameservers
332:       end
333:       #      @single_res_mutex.synchronize {

334:       if (!@resolver_ruby) # @TODO@ Synchronize this?

335:         @resolver_ruby = ResolverRuby.new(self)
336:       end
337:       #      }

338:       client_query_id = @resolver_ruby.send_async(*args)
339:       if (@single_resolvers.length == 0)
340:         Thread.start {
341:           sleep(@query_timeout == 0 ? 1 : @query_timeout)
342:           args[1].push([client_query_id, nil, ResolvTimeout.new("Query timed out - no nameservers configured")])
343:         }
344:       end
345:       return client_query_id
346:     end

send_message(message)

Send a message, and wait for the response. If a valid Message is received, then it is returned to the caller. Otherwise an exception (a Dnsruby::ResolvError or Dnsruby::ResolvTimeout) is raised.

send_async is called internally.

example :

  require 'dnsruby'
  include Dnsruby
  res = Dnsruby::Resolver.new
  begin
  response = res.send_message(Message.new("example.com", Types.MX))
  rescue ResolvError
    # ...
  rescue ResolvTimeout
    # ...
  end

[Source]

     # File lib/Dnsruby/Resolver.rb, line 211
211:     def send_message(message)
212:       Dnsruby.log.debug{"Resolver : sending message"}
213:       q = Queue.new
214:       send_async(message, q)
215:       #      # @TODO@ Add new queue tuples, e.g. :

216:       #      event_type = EventType::RECEIVED

217:       #      reply = nil

218:       #      while (event_type == EventType::RECEIVED)

219:       #        id, event_type, reply, error = q.pop

220:       #        Dnsruby.log.debug{"Resolver : result received"}

221:       #        if ((error != nil) && (event_type == EventType::ERROR))

222:       #          raise error

223:       #        end

224:       #        print "Reply = #{reply}\n"

225:       #      end

226:       #      print "Reply = #{reply}\n"

227:       #      return reply

228: 
229:       id, result, error = q.pop
230: 
231:       if (error != nil)
232:         raise error
233:       else
234:         return result
235:       end
236:     end

send_plain_message(message)

This method takes a Message (supplied by the client), and sends it to the configured nameservers. No changes are made to the Message before it is sent (TSIG signatures will be applied if configured on the Resolver). Retries are handled as the Resolver is configured to do. Incoming responses to the query are not cached or validated (although TCP fallback will be performed if the TC bit is set and the (Single)Resolver has ignore_truncation set to false). Note that the Message is left untouched - this means that no OPT records are added, even if the UDP transport for the server is specified at more than 512 bytes. If it is desired to use EDNS for this packet, then you should call the Dnsruby::PacketSender#prepare_for_dnssec(msg), or Dnsruby::PacketSender#add_opt_rr(msg) The return value from this method is the [response, error] tuple. Either of these values may be nil - it is up to the client to check.

example :

  require 'dnsruby'
  include Dnsruby
  res = Dnsruby::Resolver.new
  response, error = res.send_plain_message(Message.new("example.com", Types.MX))
  if (error)
    print "Error returned : #{error}\n"
  else
    process_response(response)
  end

[Source]

     # File lib/Dnsruby/Resolver.rb, line 264
264:     def send_plain_message(message)
265:       Dnsruby::TheLog.debug("Resolver : send_plain_message")
266:       message.do_caching = false
267:       message.do_validation = false
268:       message.send_raw = true
269:       q = Queue.new
270:       send_async(message, q)
271:       id, result, error = q.pop
272:       return [result, error]
273:     end

set_config_nameserver(n)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 435
435:     def set_config_nameserver(n)
436:       # @TODO@ Should we allow NS RRSet here? If so, then .sort_by {rand}

437:       if (!@configured)
438:         @config.get_ready
439:       end
440:       @configured = true
441:       if (n).kind_of?String
442:         @config.nameserver=[n]
443:       else
444:         @config.nameserver=n
445:       end
446:       add_config_nameservers
447:     end

src_address=(a)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 693
693:     def src_address=(a)
694:       @src_address = a
695:       update
696:     end

src_port()

The source port to send queries from Returns either a single Fixnum or an Array e.g. "0", or "[60001, 60002, 60007]"

Defaults to 0 - random port

[Source]

     # File lib/Dnsruby/Resolver.rb, line 546
546:     def src_port
547:       if (@src_port.length == 1) 
548:         return @src_port[0]
549:       end
550:       return @src_port
551:     end

src_port=(p)

Can be a single Fixnum or a Range or an Array If an invalid port is selected (one reserved by IANA), then an ArgumentError will be raised.

       res.src_port=0
       res.src_port=[60001,60005,60010]
       res.src_port=60015..60115

[Source]

     # File lib/Dnsruby/Resolver.rb, line 561
561:     def src_port=(p)
562:       if (Resolver.check_port(p))
563:         @src_port = Resolver.get_ports_from(p)
564:         update
565:       end
566:     end

tsig=(t)

Sets the TSIG to sign outgoing messages with. Pass in either a Dnsruby::RR::TSIG, or a key_name and key (or just a key) Pass in nil to stop tsig signing.

res.tsig=(tsig_rr)
res.tsig=(key_name, key) # defaults to hmac-md5
res.tsig=(key_name, key, alg) # e.g. alg = "hmac-sha1"
res.tsig=nil # Stop the resolver from signing

[Source]

     # File lib/Dnsruby/Resolver.rb, line 654
654:     def tsig=(t)
655:       @tsig=t
656:       update
657:     end

udp_size=(s)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 734
734:     def udp_size=(s)
735:       @udp_size = s
736:       update
737:     end

update_internal_res(res)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 510
510:     def update_internal_res(res)
511:       [:port, :use_tcp, :no_tcp, :tsig, :ignore_truncation, :packet_timeout,
512:         :src_address, :src_port, :recurse,
513:         :udp_size, :dnssec].each do |param|
514: 
515:         res.send(param.to_s+"=", instance_variable_get("@"+param.to_s))
516:       end
517:     end

use_tcp=(on)

[Source]

     # File lib/Dnsruby/Resolver.rb, line 637
637:     def use_tcp=(on)
638:       @use_tcp = on
639:       update
640:     end

Description

Methods

Synchronous

Asynchronous

Event Loop

Methods

Classes and Modules

Constants

Attributes

Public Class methods

Public Instance methods

Dnsruby pure Ruby event loop :

Example invocations :

Example code :