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 = 
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Instance Attribute 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

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 415

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 439

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 433

def get_ready
  if (!@configured)
    parse_config
  end
end

#inspect ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/config.rb', line 355

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 403

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) ||
      #               !@search.all? {|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 425

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 359

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