Class: Resolv::DNS::Config

Inherits:
Object
  • Object
show all
Defined in:
lib/net/dns/resolv.rb,
lib/net/dns/resolvx.rb

Overview

Encapsulates the resolver configuration information.

config_info can be nil, a String or a Hash:

- nil is the default, configuration is read from /etc/resolv.conf, or
  from Win32::Resolv.get_resolv_info on Windows.
- String is used as the name of the config file to parse instead of
  /etc/resolv.conf.
- Hash must map the :nameserver and/or :search symbol keys to a single
  String or an array of String to use as the value of those config options.

Defined Under Namespace

Classes: NXDomain, OtherResolvError

Constant Summary collapse

InitialTimeout =

:nodoc:

5

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config_info = nil) ⇒ Config

Returns a new instance of Config.



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# File 'lib/net/dns/resolv.rb', line 773

def initialize(config_info=nil)
  @mutex = Mutex.new
  @config_info = config_info
  @initialized = nil
end

Instance Attribute Details

#nameservers ⇒ Object (readonly)

The list of nameservers to query, should be dotted IP addresses, not domain names.



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# File 'lib/net/dns/resolvx.rb', line 55

def nameservers
  @nameservers
end

#ndots ⇒ Object (readonly)

A name that has a number of labels greater than than ndots will be looked up directly. The default value of ndots is 1, so “example” would not be looked up directly, but “example.com” would be (it has 1 dot). Names ending in a dot, like “org.”, will always be looked up directly, regardless of the setting of ndots.



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# File 'lib/net/dns/resolvx.rb', line 49

def ndots
  @ndots
end

#search ⇒ Object (readonly)

A series of search suffixes to use if the name being looked up does not end in a dot.



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# File 'lib/net/dns/resolvx.rb', line 52

def search
  @search
end

Class Method Details

.default_config_hash(filename = "/etc/resolv.conf") ⇒ Object

:nodoc:



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# File 'lib/net/dns/resolv.rb', line 813

def Config.default_config_hash(filename="/etc/resolv.conf") # :nodoc:
  if File.exist? filename
    config_hash = Config.parse_resolv_conf(filename)
  else
    if /mswin32|cygwin|mingw|bccwin/ =~ RUBY_PLATFORM
      search, nameserver = Win32::Resolv.get_resolv_info
      config_hash = {}
      config_hash[:nameserver] = nameserver if nameserver
      config_hash[:search] = [search].flatten if search
    end
  end
  config_hash
end

.parse_resolv_conf(filename) ⇒ Object

:nodoc:



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# File 'lib/net/dns/resolv.rb', line 779

def Config.parse_resolv_conf(filename) # :nodoc:
  nameserver = []
  search = nil
  ndots = 1
  open(filename) {|f|
    f.each {|line|
      line.sub!(/[#;].*/, '')
      keyword, *args = line.split(/\s+/)
      args.each { |arg|
        arg.untaint
      }
      next unless keyword
      case keyword
      when 'nameserver'
        nameserver += args
      when 'domain'
        next if args.empty?
        search = [args[0]]
      when 'search'
        next if args.empty?
        search = args
      when 'options'
        args.each {|arg|
          case arg
          when /\Andots:(\d+)\z/
            ndots = $1.to_i
          end
        }
      end
    }
  }
  return { :nameserver => nameserver, :search => search, :ndots => ndots }
end

Instance Method Details

#generate_candidates(name) ⇒ Object

:nodoc:



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# File 'lib/net/dns/resolv.rb', line 894

def generate_candidates(name) # :nodoc:
  candidates = nil
  name = Name.create(name)
  if name.absolute?
    candidates = [name]
  else
    if @ndots <= name.length - 1
      candidates = [Name.new(name.to_a)]
    else
      candidates = []
    end
    candidates.concat(@search.map {|domain| Name.new(name.to_a + domain)})
  end
  return candidates
end

#generate_timeouts ⇒ Object

:nodoc:



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# File 'lib/net/dns/resolv.rb', line 912

def generate_timeouts # :nodoc:
  ts = [InitialTimeout]
  ts << ts[-1] * 2 / @nameserver.length
  ts << ts[-1] * 2
  ts << ts[-1] * 2
  return ts
end

#lazy_initialize ⇒ Object

:nodoc:



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# File 'lib/net/dns/resolv.rb', line 827

def lazy_initialize # :nodoc:
  @mutex.synchronize {
    unless @initialized
      @nameserver = []
      @search = nil
      @ndots = 1
      case @config_info
      when nil
        config_hash = Config.default_config_hash
      when String
        config_hash = Config.parse_resolv_conf(@config_info)
      when Hash
        config_hash = @config_info.dup
        if String === config_hash[:nameserver]
          config_hash[:nameserver] = [config_hash[:nameserver]]
        end
        if String === config_hash[:search]
          config_hash[:search] = [config_hash[:search]]
        end
      else
        raise ArgumentError.new("invalid resolv configuration: #{@config_info.inspect}")
      end
      @nameserver = config_hash[:nameserver] if config_hash.include? :nameserver
      @search = config_hash[:search] if config_hash.include? :search
      @ndots = config_hash[:ndots] if config_hash.include? :ndots

      @nameserver = ['0.0.0.0'] if @nameserver.empty?
      if @search
        @search = @search.map {|arg| Label.split(arg) }
      else
        hostname = Socket.gethostname
        if /\./ =~ hostname
          @search = [Label.split($')]
        else
          @search = [[]]
        end
      end

      if !@nameserver.kind_of?(Array) ||
         !@nameserver.all? {|ns| String === ns }
        raise ArgumentError.new("invalid nameserver config: #{@nameserver.inspect}")
      end

      if !@search.kind_of?(Array) ||
         !@search.all? {|ls| ls.all? {|l| Label::Str === l } }
        raise ArgumentError.new("invalid search config: #{@search.inspect}")
      end

      if !@ndots.kind_of?(Integer)
        raise ArgumentError.new("invalid ndots config: #{@ndots.inspect}")
      end

      @initialized = true
    end
  }
  self
end

#resolv(name) ⇒ Object

:nodoc:



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# File 'lib/net/dns/resolv.rb', line 920

def resolv(name) # :nodoc:
  candidates = generate_candidates(name)
  timeouts = generate_timeouts
  begin
    candidates.each {|candidate|
      begin
        timeouts.each {|tout|
          @nameserver.each {|nameserver|
            begin
              yield candidate, tout, nameserver
            rescue ResolvTimeout
            end
          }
        }
        raise ResolvError.new("DNS resolv timeout: #{name}")
      rescue NXDomain
      end
    }
  rescue ResolvError
  end
end

#single? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/net/dns/resolv.rb', line 885

def single?
  lazy_initialize
  if @nameserver.length == 1
    return @nameserver[0]
  else
    return nil
  end
end