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.

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 70

def initialize()
  @mutex = Mutex.new
  parse_config
end

Instance Attribute Details

#apply_domain ⇒ Object

Should the default domain be applied?



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# File 'lib/Dnsruby/Config.rb', line 49

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 47

def apply_search_list
  @apply_search_list
end

#nameserver ⇒ Object

The list of nameservers to query



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# File 'lib/Dnsruby/Config.rb', line 45

def nameserver
  @nameserver
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 51

def ndots
  @ndots
end

Class Method Details

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

:nodoc: all



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# File 'lib/Dnsruby/Config.rb', line 286

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 227

def Config.parse_resolv_conf(filename) #:nodoc: all
  nameserver = []
  search = nil
  domain = 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?
        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 }
end

.reset ⇒ Object

Reset the config to default values



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# File 'lib/Dnsruby/Config.rb', line 75

def Config.reset
  c = Config.new
  c.parse_config
end

.resolve_server(ns) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/Config.rb', line 201

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
  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
        addr = TCPSocket.gethostbyname(ns)[3] # @TODO@ Replace this with Dnsruby call when lookups work
        server = addr
      rescue Exception => e
        TheLog.error("Can't make sense of nameserver : #{server}, exception : #{e}")
        raise ArgumentError.new("Can't make sense of nameserver : #{server}, exception : #{e}")
      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 180

def add_nameserver(ns)
  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 166

def check_ns(ns) #:nodoc: all
  if !ns.kind_of?(Array) ||
      !ns.all? {|n| (String === n || IPv4 === n || IPv6 === n)}
    raise ArgumentError.new("invalid nameserver config: #{ns.inspect}")
  end    
  ns.each_index do |i|
    ns[i]=Config.resolve_server(ns[i])
  end
end

#domain ⇒ Object

Return the default domain



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# File 'lib/Dnsruby/Config.rb', line 322

def domain
  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 122

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

#generate_candidates(name) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/Config.rb', line 337

def generate_candidates(name) #:nodoc: all
  candidates = []
  name = Name.create(name)
  if name.absolute?
    candidates = [name]
  else
    if (@apply_domain)
      if @ndots > name.length - 1
        candidates.push(Name.create(name.to_a+@domain))
      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

#inspect ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/Config.rb', line 269

def inspect #:nodoc: all
  to_s
end

#parse_config(config_info = nil) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/Config.rb', line 80

def parse_config(config_info=nil) #:nodoc: all
  @mutex.synchronize {
    ns = []
    @nameserver = []
    @domain, s, @search = nil
    dom=""
    nd = 1
    @ndots = 1
    @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
    @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
    
    send("nameserver=",ns)        
    send("search=",s)        
    send("ndots=",nd)
    send("domain=",dom)        
  }
  TheLog.info(to_s)
end

#search ⇒ Object

Return the search path



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# File 'lib/Dnsruby/Config.rb', line 313

def search
  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 142

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

This method should not normally be called by client code.



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# File 'lib/Dnsruby/Config.rb', line 65

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 329

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 273

def to_s
  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}"
  return ret
end