RCR 176: Extend resolv.rb

It would be very useful to be able to tell the Resolv::DNS class what DNS servers to use without reading them in from a file.

Resolv::DNS requires that the list of DNS servers to query comes from a specified file (/etc/resolv.conf is the default). To use arbitrary DNS servers for name resolution one must create a resolv.conf format file with the servers in it and then pass that to Resolv::DNS. This should be much easier to do.

There should be a second class (DNS2) within the Resolv class that is designed to allow the user to tell it what DNS servers to use when they instantiate the object.

A second solution might be to modify the current class to accept either a filename or the DNS server list.

Telling the object what DNS servers to use directly is much cleaner than creating files for the object to read in.

The following is a sample implementation of a DNS2 class that takes all the information found in a resolv.conf file as arguments:

require 'resolv'

class Resolv::DNS2 < Resolv::DNS
  def initialize(nameserver=['localhost'],search = nil,ndots=1)

    @mutex = Mutex.new
    @config = Config.new(nameserver,search,ndots)
    @initialized = nil
  end

  class Config < Resolv::DNS::Config
    def initialize(nameserver,search,ndots)
      @mutex = Mutex.new
      @nameserver = nameserver
      @search = search
      @ndots = ndots
      @initialized = nil
    end

    def lazy_initialize
      unless @search
        hostname = Socket.gethostname
        if /\./ =~ hostname
          @search = [Resolv::DNS::Label.split($')]
        else
          @search = [[]]
        end
      end
    end
    
  end
end