Class: TcpDNS

Inherits:
Resolv::DNS
  • Object
show all
Defined in:
lib/elbping/tcp_dns.rb

Overview

A TCP-only resolver built from ‘Resolv::DNS`. See the docs for what it’s about. ruby-doc.org/stdlib-1.9.3/libdoc/resolv/rdoc/Resolv/DNS.html

Instance Method Summary collapse

Instance Method Details

#each_resource(name, typeclass, &proc) ⇒ Object

Override fetch_resource to use a TCP requester instead of a UDP requester. This is mostly borrowed from ‘lib/resolv.rb` with the UDP->TCP fallback logic removed.



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# File 'lib/elbping/tcp_dns.rb', line 9

def each_resource(name, typeclass, &proc)
  lazy_initialize
  senders = {}
  requester = nil
  begin
    @config.resolv(name) { |candidate, tout, nameserver, port|
      requester = make_tcp_requester(nameserver, port)
      msg = Message.new
      msg.rd = 1
      msg.add_question(candidate, typeclass)
      unless sender = senders[[candidate, nameserver, port]]
        sender = senders[[candidate, nameserver, port]] =
          requester.sender(msg, candidate, nameserver, port)
      end

      begin # HACK
        reply, reply_name = requester.request(sender, tout)
      rescue
        return
      end

      case reply.rcode
      when RCode::NoError
        extract_resources(reply, reply_name, typeclass, &proc)
        return
      when RCode::NXDomain
        raise Config::NXDomain.new(reply_name.to_s)
      else
        raise Config::OtherResolvError.new(reply_name.to_s)
      end
    }
  ensure
    requester.close unless requester.nil?
  end
end