Class: Dnsruby::Recursor

Inherits:
Object
  • Object
show all
Defined in:
lib/dnsruby/recursor.rb

Overview

Dnsruby::Recursor - Perform recursive dns lookups

require 'Dnsruby'
rec = Dnsruby::Recursor.new()
answer = rec.recurse("rob.com.au")

This module uses a Dnsruby::Resolver to perform recursive queries.

AUTHOR

Rob Brown, [email protected] Alex Dalitz, [email protected]

SEE ALSO

Dnsruby::Resolver,

Copyright © 2002, Rob Brown. All rights reserved. Portions Copyright © 2005, Olaf M Kolkman. Ruby version with caching and validation Copyright © 2008, AlexD (Nominet UK)

Example lookup process:

[root@box root]# dig +trace www.rob.com.au.

; <<>> DiG 9.2.0 <<>> +trace www.rob.com.au. ;; global options: printcmd . 507343 IN NS C.ROOT-SERVERS.NET. . 507343 IN NS D.ROOT-SERVERS.NET. . 507343 IN NS E.ROOT-SERVERS.NET. . 507343 IN NS F.ROOT-SERVERS.NET. . 507343 IN NS G.ROOT-SERVERS.NET. . 507343 IN NS H.ROOT-SERVERS.NET. . 507343 IN NS I.ROOT-SERVERS.NET. . 507343 IN NS J.ROOT-SERVERS.NET. . 507343 IN NS K.ROOT-SERVERS.NET. . 507343 IN NS L.ROOT-SERVERS.NET. . 507343 IN NS M.ROOT-SERVERS.NET. . 507343 IN NS A.ROOT-SERVERS.NET. . 507343 IN NS B.ROOT-SERVERS.NET. ;; Received 436 bytes from 127.0.0.1#53(127.0.0.1) in 9 ms

;;; But these should be hard coded as the hints

;;; Ask H.ROOT-SERVERS.NET gave:

au. 172800 IN NS NS2.BERKELEY.EDU. au. 172800 IN NS NS1.BERKELEY.EDU. au. 172800 IN NS NS.UU.NET. au. 172800 IN NS BOX2.AUNIC.NET. au. 172800 IN NS SEC1.APNIC.NET. au. 172800 IN NS SEC3.APNIC.NET. ;; Received 300 bytes from 128.63.2.53#53(H.ROOT-SERVERS.NET) in 322 ms

;;; A little closer than before

;;; Ask NS2.BERKELEY.EDU gave:

com.au. 259200 IN NS ns4.ausregistry.net. com.au. 259200 IN NS dns1.telstra.net. com.au. 259200 IN NS au2ld.CSIRO.au. com.au. 259200 IN NS audns01.syd.optus.net. com.au. 259200 IN NS ns.ripe.net. com.au. 259200 IN NS ns1.ausregistry.net. com.au. 259200 IN NS ns2.ausregistry.net. com.au. 259200 IN NS ns3.ausregistry.net. com.au. 259200 IN NS ns3.melbourneit.com. ;; Received 387 bytes from 128.32.206.12#53(NS2.BERKELEY.EDU) in 10312 ms

;;; A little closer than before

;;; Ask ns4.ausregistry.net gave:

com.au. 259200 IN NS ns1.ausregistry.net. com.au. 259200 IN NS ns2.ausregistry.net. com.au. 259200 IN NS ns3.ausregistry.net. com.au. 259200 IN NS ns4.ausregistry.net. com.au. 259200 IN NS ns3.melbourneit.com. com.au. 259200 IN NS dns1.telstra.net. com.au. 259200 IN NS au2ld.CSIRO.au. com.au. 259200 IN NS ns.ripe.net. com.au. 259200 IN NS audns01.syd.optus.net. ;; Received 259 bytes from 137.39.1.3#53(ns4.ausregistry.net) in 606 ms

;;; Uh... yeah... I already knew this
;;; from what NS2.BERKELEY.EDU told me.
;;; ns4.ausregistry.net must have brain damage

;;; Ask ns1.ausregistry.net gave:

rob.com.au. 86400 IN NS sy-dns02.tmns.net.au. rob.com.au. 86400 IN NS sy-dns01.tmns.net.au. ;; Received 87 bytes from 203.18.56.41#53(ns1.ausregistry.net) in 372 ms

;;; Ah, much better.  Something more useful.

;;; Ask sy-dns02.tmns.net.au gave:

www.rob.com.au. 7200 IN A 139.134.5.123 rob.com.au. 7200 IN NS sy-dns01.tmns.net.au. rob.com.au. 7200 IN NS sy-dns02.tmns.net.au. ;; Received 135 bytes from 139.134.2.18#53(sy-dns02.tmns.net.au) in 525 ms

 ;;; FINALLY, THE ANSWER!
Now,DNSSEC validation is performed (unless disabled).

Defined Under Namespace

Classes: AddressCache

Constant Summary collapse

@@mutex =

For guarding access to shared caches.

Mutex.new
@@hints =

:nodoc: all

nil
@@authority_cache = 
Hash.new
@@zones_cache = 
nil
@@nameservers = 
nil

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(res = nil) ⇒ Recursor

Returns a new instance of Recursor.



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# File 'lib/dnsruby/recursor.rb', line 172

def initialize(res = nil)
  if (res)
    @resolver = res
  else
    if (defined?@@nameservers && @@nameservers.length > 0)
      @resolver = Resolver.new({:nameserver => @@nameservers})
    else
      @resolver = Resolver.new
    end
  end
  @resolver.dnssec = @dnssec
  @ipv6_ok = false
end

Instance Attribute Details

#callback ⇒ Object

Returns the value of attribute callback.



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# File 'lib/dnsruby/recursor.rb', line 155

def callback
  @callback
end

#dnssec ⇒ Object

Returns the value of attribute dnssec.



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# File 'lib/dnsruby/recursor.rb', line 156

def dnssec
  @dnssec
end

#hints ⇒ Object

Returns the value of attribute hints.



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# File 'lib/dnsruby/recursor.rb', line 156

def hints
  @hints
end

#ipv6_ok ⇒ Object

Returns the value of attribute ipv6_ok.



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# File 'lib/dnsruby/recursor.rb', line 155

def ipv6_ok
  @ipv6_ok
end

#nameservers ⇒ Object

Returns the value of attribute nameservers.



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# File 'lib/dnsruby/recursor.rb', line 155

def nameservers
  @nameservers
end

#recurse ⇒ Object

Returns the value of attribute recurse.



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# File 'lib/dnsruby/recursor.rb', line 155

def recurse
  @recurse
end

#resolver ⇒ Object

The resolver to use for the queries



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# File 'lib/dnsruby/recursor.rb', line 158

def resolver
  @resolver
end

Class Method Details

.add_to_hints(hints, rr) ⇒ Object 



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# File 'lib/dnsruby/recursor.rb', line 336

def Recursor.add_to_hints(hints, rr)
  server = rr.name.to_s.downcase
  server.sub!(/\.$/,"")
  if (server)
    if ( rr.type == Types::A)
      # print ";; ADDITIONAL HELP: $server -> [".$rr->rdatastr."]\n" if $self->{'debug'};
      if (hints[server]!=nil)
        TheLog.debug(";; STORING IP: #{server} IN A "+rr.address.to_s+"\n")
        hints[server].push([rr.address.to_s, rr.ttl])
      end
    end
    if ( rr.type == Types::AAAA)
      # print ";; ADDITIONAL HELP: $server -> [".$rr->rdatastr."]\n" if $self->{'debug'};
      if (hints[server])
        TheLog.debug(";; STORING IP6: #{server} IN AAAA "+rr.address.to_s+"\n")
        hints[server].push([rr.address.to_s, rr.ttl])
      end
    end

  end
end

.clear_caches(resolver = Resolver.new) ⇒ Object 



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# File 'lib/dnsruby/recursor.rb', line 381

def Recursor.clear_caches(resolver = Resolver.new)
  resolver.dnssec = @dnssec
  Recursor.set_hints(Hash.new, resolver)
  @@zones_cache = Hash.new # key zone_name, values Hash of servers and AddressCaches
  @@zones_cache["."] = @@hints

  @@authority_cache = Hash.new
end

.set_hints(hints, resolver) ⇒ Object 



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# File 'lib/dnsruby/recursor.rb', line 200

def Recursor.set_hints(hints, resolver)
  TheLog.debug(";; hints(#{hints.inspect})\n")
  @resolver = resolver
  if (resolver.single_resolvers.length == 0)
    resolver = Resolver.new()
    resolver.dnssec = @dnssec
  end
  if (hints && hints.length > 0)
    resolver.nameservers=hints
    if (String === hints)
      hints = [hints]
    end
    hints.each {|hint|
      @@hints = Hash.new
      @@hints[hint]=hint
    }
  end
  if (!hints && @@nameservers)
    @@hints=(@@nameservers)
  else
    @@nameservers=(hints)
    @@hints = hints
  end
  TheLog.debug(";; verifying (root) zone...\n")
  #  bind always asks one of the hint servers
  #  for who it thinks is authoritative for
  #  the (root) zone as a sanity check.
  #  Nice idea.

  #       if (!@@hints || @@hints.length == 0)
  resolver.recurse = true
  packet=resolver.query_no_validation_or_recursion(".", "NS", "IN")
  hints = Hash.new
  if (packet)
    if (ans = packet.answer)
      ans.each do |rr|
        if (rr.name.to_s =~ /^\.?$/ and
              rr.type == Types::NS)
          #  Found root authority
          server = rr.nsdname.to_s.downcase
          server.sub!(/\.$/,"")
          TheLog.debug(";; FOUND HINT: #{server}\n")
          hints[server] = AddressCache.new
        end
      end
      if ((packet.additional.length == 0) ||
             ((packet.additional.length == 1) && (packet.additional()[0].type == Types.OPT)))
        #  Some resolvers (e.g. 8.8.8.8) do not send an additional section -
        #  need to make explicit queries for these :(
        #  Probably best to limit the number of outstanding queries - extremely bursty behaviour otherwise
        #  What happens if we select only name
        q = Queue.new
        hints.keys.each {|server|
          #  Query for the server address and add it to hints.
          ['A', 'AAAA'].each {|type|
            msg = Message.new
            msg.do_caching = @do_caching
            msg.header.rd = false
            msg.do_validation = false
            msg.add_question(server, type, 'IN')
            if (@dnssec)
              msg.header.cd = true # We do our own validation by default
            end
            resolver.send_async(msg, q)
          }
        }
        (hints.length * 2).times {
          _id, result, _error = q.pop
          if (result)
            result.answer.each {|rr|
              TheLog.debug(";; NS address: " + rr.inspect+"\n")
              add_to_hints(hints, rr)
            }
          end
        }
      else
        packet.additional.each do |rr|
          TheLog.debug(";; ADDITIONAL: "+rr.inspect+"\n")
          add_to_hints(hints, rr)

        end
      end
    end
    #                       foreach my $server (keys %hints) {
    hints.keys.each do |server|
      if (!hints[server] || hints[server].length == 0)
        #  Wipe the servers without lookups
        hints.delete(server)
      end
    end
    @@hints = hints
  else
    @@hints = {}
  end
  if (@@hints.size > 0)
    TheLog.info(";; USING THE FOLLOWING HINT IPS:\n")
    @@hints.values.each do |ips|
      ips.each do |server|
        TheLog.info(";;  #{server}\n")
      end
    end
  else
    raise ResolvError.new( "Server ["+(@@nameservers)[0].to_s+".] did not give answers")
  end

  #  Disable recursion flag.
  resolver.recurse = false
  #       end

  #   return $self->nameservers( map { @{ $_ } } values %{ $self->{'hints'} } );
  if (Array === @@hints)
    temp = []
    @@hints.each {|hint|
      temp.push(hint)
    }
    @@hints = Hash.new
    count = 0
    temp.each {|hint|
      print "Adding hint : #{temp[count]}\n"
      @@hints[count] = temp[count]
      count += 1
    }
  end
  if (String === @@hints)
    temp = @@hints
    @@hints = Hash.new
    @@hints[0] = temp
  end
  # @@nameservers = @@hints.values
  @@nameservers=[]
  @@hints.each {|key, value|
    @@nameservers.push(key)
  }
  return @@nameservers
end

Instance Method Details

#_dorecursion(name, type, klass, known_zone, known_authorities, depth, no_validation) ⇒ Object

:nodoc:



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# File 'lib/dnsruby/recursor.rb', line 495

def _dorecursion(name, type, klass, known_zone, known_authorities, depth, no_validation) # :nodoc:

  if ( depth > 255 )
    TheLog.debug(";; _dorecursion() Recursion too deep, aborting...\n")
    @errorstring="Recursion too deep, aborted"
    return nil
  end

  known_zone = known_zone.sub(/\.*$/, ".")

  ns = [] # Array of AddressCaches (was array of array of addresses)
  @@mutex.synchronize{
    #  Get IPs from authorities
    known_authorities.keys.each do |ns_rec|
      if (known_authorities[ns_rec] != nil  && known_authorities[ns_rec] != [] )
        @@authority_cache[ns_rec] = known_authorities[ns_rec]
        ns.push(@@authority_cache[ns_rec])
      elsif (@@authority_cache[ns_rec]!=nil && @@authority_cache[ns_rec]!=[])
        known_authorities[ns_rec] = @@authority_cache[ns_rec]
        ns.push(@@authority_cache[ns_rec])
      end
    end

    if (ns.length == 0)
      found_auth = 0
      TheLog.debug(";; _dorecursion() Failed to extract nameserver IPs:")
      TheLog.debug(known_authorities.inspect + @@authority_cache.inspect)
      known_authorities.keys.each do |ns_rec|
        if (known_authorities[ns_rec]==nil || known_authorities[ns_rec]==[])
          TheLog.debug(";; _dorecursion() Manual lookup for authority [#{ns_rec}]")

          auth_packet=nil
          ans=[]

          #  Don't query for V6 if its not there.
          #  Do this in parallel
          ip_mutex = Mutex.new
          ip6_thread = Thread.start {
            if ( @ipv6_ok)
              auth_packet = _dorecursion(ns_rec,"AAAA", klass,  # packet
                ".",               # known_zone
                @@hints,  # known_authorities
                depth+1);         # depth
              ip_mutex.synchronize {
                ans.push(auth_packet.answer) if auth_packet
              }
            end
          }

          ip4_thread = Thread.start {
            auth_packet = _dorecursion(ns_rec,"A",klass,  # packet
              ".",               # known_zone
              @@hints,  # known_authorities
              depth+1);         # depth

            ip_mutex.synchronize {
              ans.push(auth_packet.answer ) if auth_packet
            }
          }
          ip6_thread.join
          ip4_thread.join

          if ( ans.length > 0 )
            TheLog.debug(";; _dorecursion() Answers found for [#{ns_rec}]")
            #           foreach my $rr (@ans) {
            ans.each do |rr_arr|
              rr_arr.each do |rr|
                TheLog.debug(";; RR:" + rr.inspect + "")
                if (rr.type == Types::CNAME)
                  #  Follow CNAME
                  server = rr.name.to_s.downcase
                  if (server)
                    server.sub!(/\.*$/, ".")
                    if (server == ns_rec)
                      cname = rr.cname.downcase
                      cname.sub!(/\.*$/, ".")
                      TheLog.debug(";; _dorecursion() Following CNAME ns [#{ns_rec}] -> [#{cname}]")
                      if (!(known_authorities[cname]))
                        known_authorities[cname] = AddressCache.new
                      end
                      known_authorities.delete(ns_rec)
                      next
                    end
                  end
                elsif (rr.type == Types::A || rr.type == Types::AAAA )
                  server = rr.name.to_s.downcase
                  if (server)
                    server.sub!(/\.*$/, ".")
                    if (known_authorities[server]!=nil)
                      ip = rr.address.to_s
                      TheLog.debug(";; _dorecursion() Found ns: #{server} IN A #{ip}")
                      @@authority_cache[server] = known_authorities[server]
                      @@authority_cache[ns_rec].push([ip, rr.ttl])
                      found_auth+=1
                      next
                    end
                  end
                end
                TheLog.debug(";; _dorecursion() Ignoring useless answer: " + rr.inspect + "")
              end
            end
          else
            TheLog.debug(";; _dorecursion() Could not find A records for [#{ns_rec}]")
          end
        end
      end
      if (found_auth > 0)
        TheLog.debug(";; _dorecursion() Found #{found_auth} new NS authorities...")
        return _dorecursion( name, type, klass, known_zone, known_authorities, depth+1)
      end
      TheLog.debug(";; _dorecursion() No authority information could be obtained.")
      return nil
    end
  }

  #  Cut the deck of IPs in a random place.
  TheLog.debug(";; _dorecursion() cutting deck of (" + ns.length.to_s + ") authorities...")
  splitpos = rand(ns.length)
  start = ns[0, splitpos]
  endarr = ns[splitpos, ns.length - splitpos]
  ns = endarr + start

  nameservers = []
  ns.each do |nss|
    nss.each {|n|
      nameservers.push(n.to_s)
    }
  end
  resolver = Resolver.new({:nameserver=>nameservers})
  resolver.dnssec = @dnssec
  resolver.recurse = false
  servers = []
  resolver.single_resolvers.each {|s|
    servers.push(s.server)
  }
  resolver.retry_delay = nameservers.length
  begin
    #  Should construct packet ourselves and clear RD bit
    query = Message.new(name, type, klass)
    query.header.rd = false
    query.do_validation = true
    query.do_caching = false
    query.do_validation = false if no_validation
    #             print "Sending msg from resolver, dnssec = #{resolver.dnssec}, do_validation = #{query.do_validation}\n"
    packet = resolver.send_message(query)
    #  @TODO@ Now prune unrelated RRSets (RFC 5452 section 6)
    prune_rrsets_to_rfc5452(packet, known_zone)
  rescue ResolvTimeout, IOError
    #             TheLog.debug(";; nameserver #{levelns.to_s} didn't respond")
    #             next
    TheLog.debug("No response!")
    return nil
  end
  if (packet) # @TODO@ Check that the packet *is* actually authoritative!!
    if (@callback)
      @callback.call(packet)
    end

    of = nil
    TheLog.debug(";; _dorecursion() Response received from [" + @answerfrom.to_s + "]")
    status = packet.rcode
    authority = packet.authority
    if (status)
      if (status == "NXDOMAIN")
        #  I guess NXDOMAIN is the best we'll ever get
        TheLog.debug(";; _dorecursion() returning NXDOMAIN")
        return packet
      elsif (packet.answer.length > 0)
        TheLog.debug(";; _dorecursion() Answers were found.")
        return packet
      elsif (packet.header.aa)
        TheLog.debug(";; _dorecursion() Authoritative answer found")
        return packet
      elsif (authority.length > 0)
        auth = Hash.new
        # 	 foreach my $rr (@authority) {
        authority.each do |rr|
          if (rr.type.to_s =~ /^(NS|SOA)$/)
            server = (rr.type == Types::NS ? rr.nsdname : rr.mname).to_s.downcase
            server.sub!(/\.*$/, ".")
            of = rr.name.to_s.downcase
            of.sub!(/\.*$/, ".")
            TheLog.debug(";; _dorecursion() Received authority [#{of}] [" + rr.type().to_s + "] [#{server}]")
            if (of.length <= known_zone.length)
              TheLog.debug(";; _dorecursion() Deadbeat name server did not provide new information.")
              next
            elsif (of =~ /#{known_zone}/)
              TheLog.debug(";; _dorecursion() FOUND closer authority for [#{of}] at [#{server}].")
              auth[server] ||= AddressCache.new #[] @TODO@ If there is no additional record for this, then we want to use the authority!
              if (rr.type == Types.NS)
                  if ((packet.additional.rrset(rr.nsdname, Types::A).length == 0) &&
                        (packet.additional.rrset(rr.nsdname, Types::AAAA).length == 0))
                    auth[server].push([rr.nsdname, rr.ttl])
                  end
              end
            else
              TheLog.debug(";; _dorecursion() Confused name server [" + @answerfrom + "] thinks [#{of}] is closer than [#{known_zone}]?")
              return nil
            end
          else
            TheLog.debug(";; _dorecursion() Ignoring NON NS entry found in authority section: " + rr.inspect)
          end
        end
        # 	 foreach my $rr ($packet->additional)
        packet.additional.each do |rr|
          if (rr.type == Types::CNAME)
            #  Store this CNAME into %auth too
            server = rr.name.to_s.downcase
            if (server)
              server.sub!(/\.*$/, ".")
              if (auth[server]!=nil && auth[server].length > 0)
                cname = rr.cname.to_s.downcase
                cname.sub!(/\.*$/, ".")
                TheLog.debug(";; _dorecursion() FOUND CNAME authority: " + rr.string)
                auth[cname] ||= AddressCache.new # []
                auth[server] = auth[cname]
                next
              end

            end
          elsif (rr.type == Types::A || rr.type == Types::AAAA)
            server = rr.name.to_s.downcase
            if (server)
              server.sub!(/\.*$/, ".")
              if (auth[server]!=nil)
                if (rr.type == Types::A)
                  TheLog.debug(";; _dorecursion() STORING: #{server} IN A    " + rr.address.to_s)
                end
                if (rr.type == Types::AAAA)
                  TheLog.debug(";; _dorecursion() STORING: #{server} IN AAAA " + rr.address.to_s)
                end
                auth[server].push([rr.address.to_s, rr.ttl])
                next
              end
            end
          end
          TheLog.debug(";; _dorecursion() Ignoring useless: " + rr.inspect)
        end
        if (of =~ /#{known_zone}/)
          #                   print "Adding #{of} with :\n#{auth}\nto zones_cache\n"
          @@mutex.synchronize{
            @@zones_cache[of]=auth
          }
          return _dorecursion( name, type, klass, of, auth, depth+1, no_validation)
        else
          return _dorecursion( name, type, klass, known_zone, known_authorities, depth+1, no_validation )
        end
      end
    end
  end

  return nil
end

#get_closest_known_zone_authorities_for(name) ⇒ Object

:nodoc:



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# File 'lib/dnsruby/recursor.rb', line 471

def get_closest_known_zone_authorities_for(name) # :nodoc:
  done = false
  known_authorities, known_zone = nil
  while (!done)
    known_zone = get_closest_known_zone_for(name)
    #         print "GOT KNOWN ZONE : #{known_zone}\n"
    @@mutex.synchronize {
      known_authorities = @@zones_cache[known_zone] # ".", @hints if nothing else
    }
    #         print "Known authorities : #{known_authorities}\n"

    #  Make sure that known_authorities still contains some authorities!
    #  If not, remove the zone from zones_cache, and start again
    if (known_authorities && known_authorities.values.length > 0)
      done = true
    else
      @@mutex.synchronize{
        @@zones_cache.delete(known_zone)
      }
    end
  end
  return known_zone, known_authorities # @TODO@ Need to synchronize access to these!
end

#get_closest_known_zone_for(n) ⇒ Object

:nodoc:



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# File 'lib/dnsruby/recursor.rb', line 435

def get_closest_known_zone_for(n) # :nodoc:
  #  Find the closest parent of name that we know
  #  e.g. for nominet.org.uk, try nominet.org.uk., org.uk., uk., .
  #  does @zones_cache contain the name we're after
  if (Name === n)
    n = n.to_s # @TODO@ This is a bit crap!
  end
  if (n == nil)
    TheLog.error("Name is nil")
    raise  ResolvError.new("Nameserver invalid!")
  end
  name = n.tr("","")
  if (name[name.length-1] != ".")
    name = name + "."
  end

  while (true)
    #         print "Checking for known zone : #{name}\n"
    zone = nil
    @@mutex.synchronize{
      zone = @@zones_cache[name]
      if (zone != nil)
        return name
      end
    }
    return false if name=="."
    #  strip the name up to the first dot
    first_dot = name.index(".")
    if (first_dot == (name.length-1))
      name = "."
    else
      name = name[first_dot+1, name.length]
    end
  end
end

#prune_rrsets_to_rfc5452(packet, zone) ⇒ Object 



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# File 'lib/dnsruby/recursor.rb', line 749

def prune_rrsets_to_rfc5452(packet, zone)
  #  Now prune the response of any unrelated rrsets (RFC5452 section6)
  #  "One very simple way to achieve this is to only accept data if it is
  #  part of the domain for which the query was intended."
  if (!packet.header.aa)
    return
  end
  if (!packet.question()[0])
    return
  end

  section_rrsets = packet.section_rrsets
  section_rrsets.keys.each {|section|
    section_rrsets[section].each {|rrset|
      n = Name.create(rrset.name)
      n.absolute = true
      if ((n.to_s == zone) || (n.to_s == Name.create(zone).to_s) ||
            (n.subdomain_of?(Name.create(zone))) ||
            (rrset.type == Types::OPT))
        #             # @TODO@ Leave in the response if it is an SOA, NSEC or RRSIGfor the parent zone
        # #          elsif ((query_name.subdomain_of?rrset.name) &&
        #           elsif  ((rrset.type == Types.SOA) || (rrset.type == Types.NSEC) || (rrset.type == Types.NSEC3)) #)
      else
        TheLog.debug"Removing #{rrset.name}, #{rrset.type} from response from server for #{zone}"
        packet.send(section).remove_rrset(rrset.name, rrset.type)
      end
    }
  }
end

#query(name, type = Types.A, klass = Classes.IN, no_validation = false) ⇒ Object

This method is much like the normal query() method except it disables the recurse flag in the packet and explicitly performs the recursion.

packet = res.query( "www.netscape.com.", "A")
packet = res.query( "www.netscape.com.", "A", "IN", true) # no validation

The Recursor maintains a cache of known nameservers. DNSSEC validation is performed unless true is passed as the fourth parameter.



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# File 'lib/dnsruby/recursor.rb', line 402

def query(name, type=Types.A, klass=Classes.IN, no_validation = false)
  #  @TODO@ PROVIDE AN ASYNCHRONOUS SEND WHICH RETURNS MESSAGE WITH ERROR!!!

  #  Make sure the hint servers are initialized.
  @@mutex.synchronize {
    self.hints=(Hash.new) unless @@hints
  }
  @resolver.recurse = false
  #  Make sure the authority cache is clean.
  #  It is only used to store A and AAAA records of
  #  the suposedly authoritative name servers.
  #  TTLs are respected
  @@mutex.synchronize {
    if (!@@zones_cache)
      Recursor.clear_caches(@resolver)
    end
  }

  #  So we have normal hashes, but the array of addresses at the end is now an AddressCache
  #  which respects the ttls of the A/AAAA records

  #  Now see if we already know the zone in question
  #  Otherwise, see if we know any of its parents (will know at least ".")
  known_zone, known_authorities = get_closest_known_zone_authorities_for(name) # ".", @hints if nothing else

  #  Seed name servers with the closest known authority
  #       ret =  _dorecursion( name, type, klass, ".", @hints, 0)
  ret =  _dorecursion( name, type, klass, known_zone, known_authorities, 0, no_validation)
  Dnssec.validate(ret) if !no_validation
  #       print "\n\nRESPONSE:\n#{ret}\n"
  return ret
end

#query_no_validation_or_recursion(name, type = Types.A, klass = Classes.IN) ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/recursor.rb', line 390

def query_no_validation_or_recursion(name, type=Types.A, klass=Classes.IN) # :nodoc: all
  return query(name, type, klass, true)
end

#recursion_callback ⇒ Object 



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# File 'lib/dnsruby/recursor.rb', line 377

def recursion_callback
  return @callback
end

#recursion_callback=(sub) ⇒ Object

This method takes a code reference, which is then invoked each time a packet is received during the recursive lookup. For example to emulate dig’s C<+trace> function:

res.recursion_callback(Proc.new { |packet|
    print packet.additional.inspect

    print";; Received %d bytes from %s\n\n",
        packetanswersize,
        packet.answerfrom);
})



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# File 'lib/dnsruby/recursor.rb', line 371

def recursion_callback=(sub)
  #           if (sub && UNIVERSAL::isa(sub, 'CODE'))
  @callback = sub
  #           end
end