Class: Dnsruby::Config

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

Overview

Description

The Config class determines the system configuration for DNS.
In particular, it determines the nameserver to target queries to.

It also specifies whether and how the search list and default
domain should be applied to queries, according to the following
algorithm :

  • If the name is absolute, then it is used as is.

  • If the name is not absolute, then :

    If apply_domain is true, and ndots is greater than the number
of labels in the name, then the default domain is added to the name.

If apply_search_list is true, then each member of the search list
is appended to the name.

The Config class has now been modified for lazy loading. Previously, the config
was loaded when a Resolver was instantiated. Now, the config is only loaded if
a query is performed (or a config parameter requested on) a Resolver which has
not yet been configured.

Constant Summary collapse

DEFAULT_PORT = 
53

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Config

Create a new Config with system default values



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# File 'lib/dnsruby/config.rb', line 85

def initialize()
  @mutex = Mutex.new
  @configured = false
end

Instance Attribute Details

#apply_domain ⇒ Object

Should the default domain be applied?



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# File 'lib/dnsruby/config.rb', line 59

def apply_domain
  @apply_domain
end

#apply_search_list ⇒ Object

Should the search list be applied?



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# File 'lib/dnsruby/config.rb', line 57

def apply_search_list
  @apply_search_list
end

Class Method Details

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

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 379

def Config.default_config_hash(filename="/etc/resolv.conf") #:nodoc: all
  config_hash={}
  if File.exist? filename
    config_hash = Config.parse_resolv_conf(filename)
  else
    if (/java/ =~ RUBY_PLATFORM && !(filename=~/:/))
      #  Problem with paths and Windows on JRuby - see if we can munge the drive...
      wd = Dir.getwd
      drive = wd.split(':')[0]
      if (drive.length==1)
        file = drive << ":" << filename
        if File.exist? file
          config_hash = Config.parse_resolv_conf(file)
        end
      end
    elsif /mswin32|cygwin|mingw|bccwin/ =~ RUBY_PLATFORM
      #  @TODO@ Need to get windows domain sorted
      search, nameserver = Win32::Resolv.get_resolv_info
      #           config_hash[:domain] = domain if domain
      config_hash[:nameserver] = nameserver if nameserver
      config_hash[:search] = [search].flatten if search
    end
  end
  config_hash
end

.parse_resolv_conf(filename) ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 311

def Config.parse_resolv_conf(filename) #:nodoc: all
  nameserver = []
  search = nil
  domain = nil
  ndots = 1
  port = DEFAULT_PORT
  open(filename) {|f|
    f.each {|line|
      line.sub!(/[#;].*/, '')
      keyword, *args = line.split(/\s+/)
        if Gem::Version.new(RUBY_VERSION) < Gem::Version.new("2.8")
          args.each { |arg|
            arg.untaint
          }
        end
      next unless keyword
      case keyword
      when 'port'
        port = args[0].to_i
      when 'nameserver'
        nameserver += args
      when 'domain'
        next if args.empty?
        domain = args[0]
        #             if search == nil
        #               search = []
        #             end
        #             search.push(args[0])
      when 'search'
        next if args.empty?
        if search == nil
          search = []
        end
        args.each {|a| search.push(a)}
      when 'options'
        args.each {|arg|
          case arg
          when /\Andots:(\d+)\z/
            ndots = $1.to_i
          end
        }
      end
    }
  }
  return { :nameserver => nameserver, :domain => domain, :search => search, :ndots => ndots, :port => port }
end

.reset ⇒ Object

Reset the config to default values



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# File 'lib/dnsruby/config.rb', line 90

def Config.reset
  @configured = false
end

.resolve_server(ns) ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 250

def Config.resolve_server(ns) #:nodoc: all
  #  Sanity check server
  #  If it's an IP address, then use that for server
  #  If it's a name, then we'll need to resolve it first
  server=ns
  if (Name === ns)
    ns = ns.to_s
  end
  begin
    addr = IPv4.create(ns)
    server = ns
  rescue Exception
    begin
      addr=IPv6.create(ns)
      server = ns
    rescue Exception
      begin
        #  try to resolve server to address
        if ns == "localhost"
          server = "127.0.0.1"
        else
          #  Use Dnsruby to resolve the servers
          #  First, try the default resolvers
          resolver = Resolver.new
          found = false
          begin
            ret = resolver.query(ns)
            ret.answer.each {|rr|
              if ([Types::A, Types::AAAA].include?rr.type)
                addr = rr.address.to_s
                server = addr
                found = true
              end
            }
          rescue Exception
          end
          if (!found)
            #  That didn't work - try recursing from the root
            recursor = Recursor.new
            ret = recursor.query(ns)
            ret.answer.each {|rr|
              if ([Types::A, Types::AAAA].include?rr.type)
                addr = rr.address.to_s
                server = addr
              end
            }
            if (!found)
              raise ArgumentError.new("Recursor can't locate #{server}")
            end
          end
        end
      rescue Exception => e
        Dnsruby.log.error{"Can't make sense of nameserver : #{server}, exception : #{e}"}
        raise ArgumentError.new("Can't make sense of nameserver : #{server}, exception : #{e}")
        return nil
      end
    end
  end
  return server
end

Instance Method Details

#add_nameserver(ns) ⇒ Object

Add a nameserver to the list of nameservers.

Can take either a single String or an array of Strings.
The new nameservers are added at a higher priority.



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# File 'lib/dnsruby/config.rb', line 227

def add_nameserver(ns)
  @configured = true
  if (ns.kind_of?String)
    ns=[ns]
  end
  check_ns(ns)
  ns.reverse_each do |n|
    if (!@nameserver.include?(n))
      self.nameserver=[n]+@nameserver
    end
  end
end

#check_ns(ns) ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 198

def check_ns(ns) #:nodoc: all
  if !ns.kind_of?(Array) ||
      !ns.all? {|n| (Name === n || String === n || IPv4 === n || IPv6 === n)}
    raise ArgumentError.new("invalid nameserver config: #{ns.inspect}")
  end
  ns.each {|n|
    if (String ===n)
      #  Make sure we can make a Name or an address from it
      begin
        IPv4.create(n)
      rescue ArgumentError
        begin
          IPv6.create(n)
        rescue ArgumentError
          begin
            Name.create(n)
          rescue ArgumentError
            raise ArgumentError.new("Can't interpret #{n} as IPv4, IPv6 or Name")
          end
        end
      end
    end
  }
end

#domain ⇒ Object

Return the default domain



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# File 'lib/dnsruby/config.rb', line 418

def domain
  if (!@configured)
    parse_config
  end
  if (@domain==nil)
    return nil
  end
  return Name.create(@domain).to_s
end

#domain=(dom) ⇒ Object

Set the default domain



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# File 'lib/dnsruby/config.rb', line 142

def domain=(dom)
  #       @configured = true
  if (dom)
    if !dom.kind_of?(String)
      raise ArgumentError.new("invalid domain config: #{@domain.inspect}")
    end
    @domain = Name::split(dom)
  else
    @domain=nil
  end
end

#generate_candidates(name_in) ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 442

def generate_candidates(name_in) #:nodoc: all
  if !@configured
    parse_config
  end
  candidates = []
  name = Name.create(name_in)
  if name.absolute?
    candidates = [name]
  else
    candidates.push(Name.create(name_in.to_s + "."))
    if (@apply_domain)
      if @ndots > name.length - 1
        if (@domain != nil)
          candidates.push(Name.create(name.to_a+@domain))
        end
      end
    end
    if (!@apply_search_list)
      candidates.push(Name.create(name.to_a))
    else
      if @ndots <= name.length - 1
        candidates.push(Name.create(name.to_a))
      end
      candidates.concat(@search.map {|domain| Name.create(name.to_a + domain)})
      if (name.length == 1)
        candidates.concat([Name.create(name.to_a)])
      end
    end
  end
  return candidates
end

#get_ready ⇒ Object 



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# File 'lib/dnsruby/config.rb', line 436

def get_ready
  if (!@configured)
    parse_config
  end
end

#inspect ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 358

def inspect #:nodoc: all
  to_s
end

#nameserver ⇒ Object

The list of nameservers to query



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# File 'lib/dnsruby/config.rb', line 50

def nameserver
  if (!@configured)
    parse_config
  end
  return @nameserver
end

#nameserver=(ns) ⇒ Object

Set the config to point to a single nameserver



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# File 'lib/dnsruby/config.rb', line 241

def nameserver=(ns)
  @configured = true
  check_ns(ns)
  #       @nameserver = ['0.0.0.0'] if (@nameserver.class != Array || @nameserver.empty?)
  #  Now go through and ensure that all ns point to IP addresses, not domain names
  @nameserver=ns
  Dnsruby.log.debug{"Nameservers = #{@nameserver.join(", ")}"}
end

#ndots ⇒ Object

The minimum number of labels in the query name (if it is not absolute) before it is considered complete



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# File 'lib/dnsruby/config.rb', line 61

def ndots
  if (!@configured)
    parse_config
  end
  return @ndots
end

#ndots=(nd) ⇒ Object

Set ndots



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

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

#parse_config(config_info = nil) ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 94

def parse_config(config_info=nil) #:nodoc: all
  @mutex.synchronize {
    ns = []
    @nameserver = []
    @domain, s, @search = nil
    dom=""
    nd = 1
    @ndots = 1
    @port = DEFAULT_PORT
    @apply_search_list = true
    @apply_domain = true
    config_hash = Config.default_config_hash
    case config_info
    when nil
    when String
      config_hash.merge!(Config.parse_resolv_conf(config_info))
    when Hash
      config_hash.merge!(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
    ns = config_hash[:nameserver] if config_hash.include? :nameserver
    s = config_hash[:search] if config_hash.include? :search
    nd = config_hash[:ndots] if config_hash.include? :ndots
    p = config_hash[:port] if config_hash.include? :port
    @apply_search_list = config_hash[:apply_search_list] if config_hash.include? :apply_search_list
    @apply_domain= config_hash[:apply_domain] if config_hash.include? :apply_domain
    dom = config_hash[:domain] if config_hash.include? :domain

    if (!@configured)
      send("nameserver=",ns)
    end
    @configured = true
    send("search=",s)
    send("ndots=",nd)
    send("port=",p)
    send("domain=",dom)
  }
  Dnsruby.log.info{to_s}
end

#port=(p) ⇒ Object

Set port



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# File 'lib/dnsruby/config.rb', line 164

def port=(p)
  @configured = true
  @port=p if p
  if !@port.kind_of?(Integer)
    raise ArgumentError.new("invalid port config: #{@port.inspect}")
  end
end

#search ⇒ Object

Return the search path



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# File 'lib/dnsruby/config.rb', line 406

def search
  if (!@configured)
    parse_config
  end
  search = []
  @search.each do |s|
    search.push(Name.new(s).to_s)
  end
  return search
end

#search=(s) ⇒ Object

Set the default search path



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# File 'lib/dnsruby/config.rb', line 173

def search=(s)
  @configured = true
  @search=s
  if @search
    if @search.class == Array
      @search = @search.map {|arg| Name::split(arg) }
    else
      raise ArgumentError.new("invalid search config: search must be an array!")
    end
  else
    hostname = Socket.gethostname
    if /\./ =~ hostname
      @search = [Name.split($')]
    else
      @search = [[]]
    end
  end

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

#set_config_info(config_info) ⇒ Object

Set the config. Parameter can be :

* A String containing the name of the config file to load
       e.g. /etc/resolv.conf

* A hash with the following elements :
       nameserver (String)
       domain (String)
       search (String)
       ndots (Integer)

This method should not normally be called by client code.



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# File 'lib/dnsruby/config.rb', line 80

def set_config_info(config_info)
  parse_config(config_info)
end

#single? ⇒ Boolean

:nodoc: all

Returns:

  • (Boolean) 


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# File 'lib/dnsruby/config.rb', line 428

def single? #:nodoc: all
  if @nameserver.length == 1
    return @nameserver[0]
  else
    return nil
  end
end

#to_s ⇒ Object 



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# File 'lib/dnsruby/config.rb', line 362

def to_s
  if (!@configured)
    parse_config
  end
  ret = "Config - nameservers : "
  @nameserver.each {|n| ret += n.to_s + ", "}
  domain_string="empty"
  if (@domain!=nil)
    domain_string=@domain.to_s
  end
  ret += " domain : #{domain_string}, search : "
  search.each {|s| ret += s + ", " }
  ret += " ndots : #{@ndots}"
  ret += " port : #{@port}"
  return ret
end