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Edit File : resolv.rb \| Size : 59.91 KB
require 'socket' require 'fcntl' require 'timeout' require 'thread' begin require 'securerandom' rescue LoadError end # Resolv is a thread-aware DNS resolver library written in Ruby. Resolv can # handle multiple DNS requests concurrently without blocking the entire ruby # interpreter. # # See also resolv-replace.rb to replace the libc resolver with Resolv. # # Resolv can look up various DNS resources using the DNS module directly. # # Examples: # # p Resolv.getaddress "www.ruby-lang.org" # p Resolv.getname "210.251.121.214" # # Resolv::DNS.open do \|dns\| # ress = dns.getresources "www.ruby-lang.org", Resolv::DNS::Resource::IN::A # p ress.map { \|r\| r.address } # ress = dns.getresources "ruby-lang.org", Resolv::DNS::Resource::IN::MX # p ress.map { \|r\| [r.exchange.to_s, r.preference] } # end # # # == Bugs # # * NIS is not supported. # * /etc/nsswitch.conf is not supported. class Resolv ## # Looks up the first IP address for +name+. def self.getaddress(name) DefaultResolver.getaddress(name) end ## # Looks up all IP address for +name+. def self.getaddresses(name) DefaultResolver.getaddresses(name) end ## # Iterates over all IP addresses for +name+. def self.each_address(name, &block) DefaultResolver.each_address(name, &block) end ## # Looks up the hostname of +address+. def self.getname(address) DefaultResolver.getname(address) end ## # Looks up all hostnames for +address+. def self.getnames(address) DefaultResolver.getnames(address) end ## # Iterates over all hostnames for +address+. def self.each_name(address, &proc) DefaultResolver.each_name(address, &proc) end ## # Creates a new Resolv using +resolvers+. def initialize(resolvers=[Hosts.new, DNS.new]) @resolvers = resolvers end ## # Looks up the first IP address for +name+. def getaddress(name) each_address(name) {\|address\| return address} raise ResolvError.new("no address for #{name}") end ## # Looks up all IP address for +name+. def getaddresses(name) ret = [] each_address(name) {\|address\| ret << address} return ret end ## # Iterates over all IP addresses for +name+. def each_address(name) if AddressRegex =~ name yield name return end yielded = false @resolvers.each {\|r\| r.each_address(name) {\|address\| yield address.to_s yielded = true } return if yielded } end ## # Looks up the hostname of +address+. def getname(address) each_name(address) {\|name\| return name} raise ResolvError.new("no name for #{address}") end ## # Looks up all hostnames for +address+. def getnames(address) ret = [] each_name(address) {\|name\| ret << name} return ret end ## # Iterates over all hostnames for +address+. def each_name(address) yielded = false @resolvers.each {\|r\| r.each_name(address) {\|name\| yield name.to_s yielded = true } return if yielded } end ## # Indicates a failure to resolve a name or address. class ResolvError < StandardError; end ## # Indicates a timeout resolving a name or address. class ResolvTimeout < TimeoutError; end ## # Resolv::Hosts is a hostname resolver that uses the system hosts file. class Hosts if /mswin\|mingw\|bccwin/ =~ RUBY_PLATFORM require 'win32/resolv' DefaultFileName = Win32::Resolv.get_hosts_path else DefaultFileName = '/etc/hosts' end ## # Creates a new Resolv::Hosts, using +filename+ for its data source. def initialize(filename = DefaultFileName) @filename = filename @mutex = Mutex.new @initialized = nil end def lazy_initialize # :nodoc: @mutex.synchronize { unless @initialized @name2addr = {} @addr2name = {} open(@filename, 'rb') {\|f\| f.each {\|line\| line.sub!(/#./, '') addr, hostname, aliases = line.split(/\s+/) next unless addr addr.untaint hostname.untaint @addr2name[addr] = [] unless @addr2name.include? addr @addr2name[addr] << hostname @addr2name[addr] += aliases @name2addr[hostname] = [] unless @name2addr.include? hostname @name2addr[hostname] << addr aliases.each {\|n\| n.untaint @name2addr[n] = [] unless @name2addr.include? n @name2addr[n] << addr } } } @name2addr.each {\|name, arr\| arr.reverse!} @initialized = true end } self end ## # Gets the IP address of +name+ from the hosts file. def getaddress(name) each_address(name) {\|address\| return address} raise ResolvError.new("#{@filename} has no name: #{name}") end ## # Gets all IP addresses for +name+ from the hosts file. def getaddresses(name) ret = [] each_address(name) {\|address\| ret << address} return ret end ## # Iterates over all IP addresses for +name+ retrieved from the hosts file. def each_address(name, &proc) lazy_initialize if @name2addr.include?(name) @name2addr[name].each(&proc) end end ## # Gets the hostname of +address+ from the hosts file. def getname(address) each_name(address) {\|name\| return name} raise ResolvError.new("#{@filename} has no address: #{address}") end ## # Gets all hostnames for +address+ from the hosts file. def getnames(address) ret = [] each_name(address) {\|name\| ret << name} return ret end ## # Iterates over all hostnames for +address+ retrieved from the hosts file. def each_name(address, &proc) lazy_initialize if @addr2name.include?(address) @addr2name[address].each(&proc) end end end ## # Resolv::DNS is a DNS stub resolver. # # Information taken from the following places: # # * STD0013 # * RFC 1035 # * ftp://ftp.isi.edu/in-notes/iana/assignments/dns-parameters # * etc. class DNS ## # Default DNS Port Port = 53 ## # Default DNS UDP packet size UDPSize = 512 ## # Creates a new DNS resolver. See Resolv::DNS.new for argument details. # # Yields the created DNS resolver to the block, if given, otherwise # returns it. def self.open(args) dns = new(args) return dns unless block_given? begin yield dns ensure dns.close end end ## # Creates a new DNS resolver. # # +config_info+ can be: # # nil:: Uses /etc/resolv.conf. # String:: Path to a file using /etc/resolv.conf's format. # Hash:: Must contain :nameserver, :search and :ndots keys. # :nameserver_port can be used to specify port number of nameserver address. # # The value of :nameserver should be an address string or # an array of address strings. # - :nameserver => '8.8.8.8' # - :nameserver => ['8.8.8.8', '8.8.4.4'] # # The value of :nameserver_port should be an array of # pair of nameserver address and port number. # - :nameserver_port => [['8.8.8.8', 53], ['8.8.4.4', 53]] # # Example: # # Resolv::DNS.new(:nameserver => ['210.251.121.21'], # :search => ['ruby-lang.org'], # :ndots => 1) def initialize(config_info=nil) @mutex = Mutex.new @config = Config.new(config_info) @initialized = nil end def lazy_initialize # :nodoc: @mutex.synchronize { unless @initialized @config.lazy_initialize @initialized = true end } self end ## # Closes the DNS resolver. def close @mutex.synchronize { if @initialized @initialized = false end } end ## # Gets the IP address of +name+ from the DNS resolver. # # +name+ can be a Resolv::DNS::Name or a String. Retrieved address will # be a Resolv::IPv4 or Resolv::IPv6 def getaddress(name) each_address(name) {\|address\| return address} raise ResolvError.new("DNS result has no information for #{name}") end ## # Gets all IP addresses for +name+ from the DNS resolver. # # +name+ can be a Resolv::DNS::Name or a String. Retrieved addresses will # be a Resolv::IPv4 or Resolv::IPv6 def getaddresses(name) ret = [] each_address(name) {\|address\| ret << address} return ret end ## # Iterates over all IP addresses for +name+ retrieved from the DNS # resolver. # # +name+ can be a Resolv::DNS::Name or a String. Retrieved addresses will # be a Resolv::IPv4 or Resolv::IPv6 def each_address(name) each_resource(name, Resource::IN::A) {\|resource\| yield resource.address} if use_ipv6? each_resource(name, Resource::IN::AAAA) {\|resource\| yield resource.address} end end def use_ipv6? # :nodoc: begin list = Socket.ip_address_list rescue NotImplementedError return true end list.any? {\|a\| a.ipv6? && !a.ipv6_loopback? && !a.ipv6_linklocal? } end private :use_ipv6? ## # Gets the hostname for +address+ from the DNS resolver. # # +address+ must be a Resolv::IPv4, Resolv::IPv6 or a String. Retrieved # name will be a Resolv::DNS::Name. def getname(address) each_name(address) {\|name\| return name} raise ResolvError.new("DNS result has no information for #{address}") end ## # Gets all hostnames for +address+ from the DNS resolver. # # +address+ must be a Resolv::IPv4, Resolv::IPv6 or a String. Retrieved # names will be Resolv::DNS::Name instances. def getnames(address) ret = [] each_name(address) {\|name\| ret << name} return ret end ## # Iterates over all hostnames for +address+ retrieved from the DNS # resolver. # # +address+ must be a Resolv::IPv4, Resolv::IPv6 or a String. Retrieved # names will be Resolv::DNS::Name instances. def each_name(address) case address when Name ptr = address when IPv4::Regex ptr = IPv4.create(address).to_name when IPv6::Regex ptr = IPv6.create(address).to_name else raise ResolvError.new("cannot interpret as address: #{address}") end each_resource(ptr, Resource::IN::PTR) {\|resource\| yield resource.name} end ## # Look up the +typeclass+ DNS resource of +name+. # # +name+ must be a Resolv::DNS::Name or a String. # # +typeclass+ should be one of the following: # # * Resolv::DNS::Resource::IN::A # * Resolv::DNS::Resource::IN::AAAA # * Resolv::DNS::Resource::IN::ANY # * Resolv::DNS::Resource::IN::CNAME # * Resolv::DNS::Resource::IN::HINFO # * Resolv::DNS::Resource::IN::MINFO # * Resolv::DNS::Resource::IN::MX # * Resolv::DNS::Resource::IN::NS # * Resolv::DNS::Resource::IN::PTR # * Resolv::DNS::Resource::IN::SOA # * Resolv::DNS::Resource::IN::TXT # * Resolv::DNS::Resource::IN::WKS # # Returned resource is represented as a Resolv::DNS::Resource instance, # i.e. Resolv::DNS::Resource::IN::A. def getresource(name, typeclass) each_resource(name, typeclass) {\|resource\| return resource} raise ResolvError.new("DNS result has no information for #{name}") end ## # Looks up all +typeclass+ DNS resources for +name+. See #getresource for # argument details. def getresources(name, typeclass) ret = [] each_resource(name, typeclass) {\|resource\| ret << resource} return ret end ## # Iterates over all +typeclass+ DNS resources for +name+. See # #getresource for argument details. def each_resource(name, typeclass, &proc) lazy_initialize requester = make_udp_requester senders = {} begin @config.resolv(name) {\|candidate, tout, nameserver, port\| msg = Message.new msg.rd = 1 msg.add_question(candidate, typeclass) unless sender = senders[[candidate, nameserver, port]] sender = requester.sender(msg, candidate, nameserver, port) next if !sender senders[[candidate, nameserver, port]] = sender end reply, reply_name = requester.request(sender, tout) case reply.rcode when RCode::NoError if reply.tc == 1 and not Requester::TCP === requester requester.close # Retry via TCP: requester = make_tcp_requester(nameserver, port) senders = {} # This will use TCP for all remaining candidates (assuming the # current candidate does not already respond successfully via # TCP). This makes sense because we already know the full # response will not fit in an untruncated UDP packet. redo else extract_resources(reply, reply_name, typeclass, &proc) end return when RCode::NXDomain raise Config::NXDomain.new(reply_name.to_s) else raise Config::OtherResolvError.new(reply_name.to_s) end } ensure requester.close end end def make_udp_requester # :nodoc: nameserver_port = @config.nameserver_port if nameserver_port.length == 1 Requester::ConnectedUDP.new(nameserver_port[0]) else Requester::UnconnectedUDP.new(nameserver_port) end end def make_tcp_requester(host, port) # :nodoc: return Requester::TCP.new(host, port) end def extract_resources(msg, name, typeclass) # :nodoc: if typeclass < Resource::ANY n0 = Name.create(name) msg.each_answer {\|n, ttl, data\| yield data if n0 == n } end yielded = false n0 = Name.create(name) msg.each_answer {\|n, ttl, data\| if n0 == n case data when typeclass yield data yielded = true when Resource::CNAME n0 = data.name end end } return if yielded msg.each_answer {\|n, ttl, data\| if n0 == n case data when typeclass yield data end end } end if defined? SecureRandom def self.random(arg) # :nodoc: begin SecureRandom.random_number(arg) rescue NotImplementedError rand(arg) end end else def self.random(arg) # :nodoc: rand(arg) end end def self.rangerand(range) # :nodoc: base = range.begin len = range.end - range.begin if !range.exclude_end? len += 1 end base + random(len) end RequestID = {} # :nodoc: RequestIDMutex = Mutex.new # :nodoc: def self.allocate_request_id(host, port) # :nodoc: id = nil RequestIDMutex.synchronize { h = (RequestID[[host, port]] \|\|= {}) begin id = rangerand(0x0000..0xffff) end while h[id] h[id] = true } id end def self.free_request_id(host, port, id) # :nodoc: RequestIDMutex.synchronize { key = [host, port] if h = RequestID[key] h.delete id if h.empty? RequestID.delete key end end } end def self.bind_random_port(udpsock, bind_host="0.0.0.0") # :nodoc: begin port = rangerand(1024..65535) udpsock.bind(bind_host, port) rescue Errno::EADDRINUSE retry end end class Requester # :nodoc: def initialize @senders = {} @socks = nil end def request(sender, tout) timelimit = Time.now + tout sender.send while true now = Time.now timeout = timelimit - now if timeout <= 0 raise ResolvTimeout end select_result = IO.select(@socks, nil, nil, timeout) if !select_result raise ResolvTimeout end begin reply, from = recv_reply(select_result[0]) rescue Errno::ECONNREFUSED, # GNU/Linux, FreeBSD Errno::ECONNRESET # Windows # No name server running on the server? # Don't wait anymore. raise ResolvTimeout end begin msg = Message.decode(reply) rescue DecodeError next # broken DNS message ignored end if s = @senders[[from,msg.id]] break else # unexpected DNS message ignored end end return msg, s.data end def close socks = @socks @socks = nil if socks socks.each {\|sock\| sock.close } end end class Sender # :nodoc: def initialize(msg, data, sock) @msg = msg @data = data @sock = sock end end class UnconnectedUDP < Requester # :nodoc: def initialize(nameserver_port) super() @nameserver_port = nameserver_port @socks_hash = {} @socks = [] nameserver_port.each {\|host, port\| if host.index(':') bind_host = "::" af = Socket::AF_INET6 else bind_host = "0.0.0.0" af = Socket::AF_INET end next if @socks_hash[bind_host] begin sock = UDPSocket.new(af) rescue Errno::EAFNOSUPPORT next # The kernel doesn't support the address family. end sock.do_not_reverse_lookup = true sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD DNS.bind_random_port(sock, bind_host) @socks << sock @socks_hash[bind_host] = sock } end def recv_reply(readable_socks) reply, from = readable_socks[0].recvfrom(UDPSize) return reply, [from[3],from[1]] end def sender(msg, data, host, port=Port) sock = @socks_hash[host.index(':') ? "::" : "0.0.0.0"] return nil if !sock service = [host, port] id = DNS.allocate_request_id(host, port) request = msg.encode request[0,2] = [id].pack('n') return @senders[[service, id]] = Sender.new(request, data, sock, host, port) end def close super @senders.each_key {\|service, id\| DNS.free_request_id(service[0], service[1], id) } end class Sender < Requester::Sender # :nodoc: def initialize(msg, data, sock, host, port) super(msg, data, sock) @host = host @port = port end attr_reader :data def send raise "@sock is nil." if @sock.nil? @sock.send(@msg, 0, @host, @port) end end end class ConnectedUDP < Requester # :nodoc: def initialize(host, port=Port) super() @host = host @port = port is_ipv6 = host.index(':') sock = UDPSocket.new(is_ipv6 ? Socket::AF_INET6 : Socket::AF_INET) @socks = [sock] sock.do_not_reverse_lookup = true sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD DNS.bind_random_port(sock, is_ipv6 ? "::" : "0.0.0.0") sock.connect(host, port) end def recv_reply(readable_socks) reply = readable_socks[0].recv(UDPSize) return reply, nil end def sender(msg, data, host=@host, port=@port) unless host == @host && port == @port raise RequestError.new("host/port don't match: #{host}:#{port}") end id = DNS.allocate_request_id(@host, @port) request = msg.encode request[0,2] = [id].pack('n') return @senders[[nil,id]] = Sender.new(request, data, @socks[0]) end def close super @senders.each_key {\|from, id\| DNS.free_request_id(@host, @port, id) } end class Sender < Requester::Sender # :nodoc: def send raise "@sock is nil." if @sock.nil? @sock.send(@msg, 0) end attr_reader :data end end class TCP < Requester # :nodoc: def initialize(host, port=Port) super() @host = host @port = port sock = TCPSocket.new(@host, @port) @socks = [sock] sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD @senders = {} end def recv_reply(readable_socks) len = readable_socks[0].read(2).unpack('n')[0] reply = @socks[0].read(len) return reply, nil end def sender(msg, data, host=@host, port=@port) unless host == @host && port == @port raise RequestError.new("host/port don't match: #{host}:#{port}") end id = DNS.allocate_request_id(@host, @port) request = msg.encode request[0,2] = [request.length, id].pack('nn') return @senders[[nil,id]] = Sender.new(request, data, @socks[0]) end class Sender < Requester::Sender # :nodoc: def send @sock.print(@msg) @sock.flush end attr_reader :data end def close super @senders.each_key {\|from,id\| DNS.free_request_id(@host, @port, id) } end end ## # Indicates a problem with the DNS request. class RequestError < StandardError end end class Config # :nodoc: def initialize(config_info=nil) @mutex = Mutex.new @config_info = config_info @initialized = nil end def Config.parse_resolv_conf(filename) nameserver = [] search = nil ndots = 1 open(filename, 'rb') {\|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 = $1.to_i end } end } } return { :nameserver => nameserver, :search => search, :ndots => ndots } end def Config.default_config_hash(filename="/etc/resolv.conf") if File.exist? filename config_hash = Config.parse_resolv_conf(filename) else if /mswin\|cygwin\|mingw\|bccwin/ =~ RUBY_PLATFORM require 'win32/resolv' search, nameserver = Win32::Resolv.get_resolv_info config_hash = {} config_hash[:nameserver] = nameserver if nameserver config_hash[:search] = [search].flatten if search end end config_hash \|\| {} end def lazy_initialize @mutex.synchronize { unless @initialized @nameserver_port = [] @search = nil @ndots = 1 case @config_info when nil config_hash = Config.default_config_hash when String config_hash = Config.parse_resolv_conf(@config_info) when Hash config_hash = @config_info.dup if String === config_hash[:nameserver] config_hash[:nameserver] = [config_hash[:nameserver]] end if String === config_hash[:search] config_hash[:search] = [config_hash[:search]] end else raise ArgumentError.new("invalid resolv configuration: #{@config_info.inspect}") end if config_hash.include? :nameserver @nameserver_port = config_hash[:nameserver].map {\|ns\| [ns, Port] } end if config_hash.include? :nameserver_port @nameserver_port = config_hash[:nameserver_port].map {\|ns, port\| [ns, (port \|\| Port)] } end @search = config_hash[:search] if config_hash.include? :search @ndots = config_hash[:ndots] if config_hash.include? :ndots if @nameserver_port.empty? @nameserver_port << ['0.0.0.0', Port] end if @search @search = @search.map {\|arg\| Label.split(arg) } else hostname = Socket.gethostname if /\./ =~ hostname @search = [Label.split($')] else @search = [[]] end end if !@nameserver_port.kind_of?(Array) \|\| @nameserver_port.any? {\|ns_port\| !(Array === ns_port) \|\| ns_port.length != 2 !(String === ns_port[0]) \|\| !(Integer === ns_port[1]) } raise ArgumentError.new("invalid nameserver config: #{@nameserver_port.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 def single? lazy_initialize if @nameserver_port.length == 1 return @nameserver_port[0] else return nil end end def nameserver_port @nameserver_port end def generate_candidates(name) 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 InitialTimeout = 5 def generate_timeouts ts = [InitialTimeout] ts << ts[-1] 2 / @nameserver_port.length ts << ts[-1] * 2 ts << ts[-1] * 2 return ts end def resolv(name) candidates = generate_candidates(name) timeouts = generate_timeouts begin candidates.each {\|candidate\| begin timeouts.each {\|tout\| @nameserver_port.each {\|nameserver, port\| begin yield candidate, tout, nameserver, port rescue ResolvTimeout end } } raise ResolvError.new("DNS resolv timeout: #{name}") rescue NXDomain end } rescue ResolvError end end ## # Indicates no such domain was found. class NXDomain < ResolvError end ## # Indicates some other unhandled resolver error was encountered. class OtherResolvError < ResolvError end end module OpCode # :nodoc: Query = 0 IQuery = 1 Status = 2 Notify = 4 Update = 5 end module RCode # :nodoc: NoError = 0 FormErr = 1 ServFail = 2 NXDomain = 3 NotImp = 4 Refused = 5 YXDomain = 6 YXRRSet = 7 NXRRSet = 8 NotAuth = 9 NotZone = 10 BADVERS = 16 BADSIG = 16 BADKEY = 17 BADTIME = 18 BADMODE = 19 BADNAME = 20 BADALG = 21 end ## # Indicates that the DNS response was unable to be decoded. class DecodeError < StandardError end ## # Indicates that the DNS request was unable to be encoded. class EncodeError < StandardError end module Label # :nodoc: def self.split(arg) labels = [] arg.scan(/[^\.]+/) {labels << Str.new($&)} return labels end class Str # :nodoc: def initialize(string) @string = string @downcase = string.downcase end attr_reader :string, :downcase def to_s return @string end def inspect return "#<#{self.class} #{self.to_s}>" end def ==(other) return @downcase == other.downcase end def eql?(other) return self == other end def hash return @downcase.hash end end end ## # A representation of a DNS name. class Name ## # Creates a new DNS name from +arg+. +arg+ can be: # # Name:: returns +arg+. # String:: Creates a new Name. def self.create(arg) case arg when Name return arg when String return Name.new(Label.split(arg), /\.\z/ =~ arg ? true : false) else raise ArgumentError.new("cannot interpret as DNS name: #{arg.inspect}") end end def initialize(labels, absolute=true) # :nodoc: @labels = labels @absolute = absolute end def inspect # :nodoc: "#<#{self.class}: #{self.to_s}#{@absolute ? '.' : ''}>" end ## # True if this name is absolute. def absolute? return @absolute end def ==(other) # :nodoc: return false unless Name === other return @labels.join == other.to_a.join && @absolute == other.absolute? end alias eql? == # :nodoc: ## # Returns true if +other+ is a subdomain. # # Example: # # domain = Resolv::DNS::Name.create("y.z") # p Resolv::DNS::Name.create("w.x.y.z").subdomain_of?(domain) #=> true # p Resolv::DNS::Name.create("x.y.z").subdomain_of?(domain) #=> true # p Resolv::DNS::Name.create("y.z").subdomain_of?(domain) #=> false # p Resolv::DNS::Name.create("z").subdomain_of?(domain) #=> false # p Resolv::DNS::Name.create("x.y.z.").subdomain_of?(domain) #=> false # p Resolv::DNS::Name.create("w.z").subdomain_of?(domain) #=> false # def subdomain_of?(other) raise ArgumentError, "not a domain name: #{other.inspect}" unless Name === other return false if @absolute != other.absolute? other_len = other.length return false if @labels.length <= other_len return @labels[-other_len, other_len] == other.to_a end def hash # :nodoc: return @labels.hash ^ @absolute.hash end def to_a # :nodoc: return @labels end def length # :nodoc: return @labels.length end def [](i) # :nodoc: return @labels[i] end ## # returns the domain name as a string. # # The domain name doesn't have a trailing dot even if the name object is # absolute. # # Example: # # p Resolv::DNS::Name.create("x.y.z.").to_s #=> "x.y.z" # p Resolv::DNS::Name.create("x.y.z").to_s #=> "x.y.z" def to_s return @labels.join('.') end end class Message # :nodoc: @@identifier = -1 def initialize(id = (@@identifier += 1) & 0xffff) @id = id @qr = 0 @opcode = 0 @aa = 0 @tc = 0 @rd = 0 # recursion desired @ra = 0 # recursion available @rcode = 0 @question = [] @answer = [] @authority = [] @additional = [] end attr_accessor :id, :qr, :opcode, :aa, :tc, :rd, :ra, :rcode attr_reader :question, :answer, :authority, :additional def ==(other) return @id == other.id && @qr == other.qr && @opcode == other.opcode && @aa == other.aa && @tc == other.tc && @rd == other.rd && @ra == other.ra && @rcode == other.rcode && @question == other.question && @answer == other.answer && @authority == other.authority && @additional == other.additional end def add_question(name, typeclass) @question << [Name.create(name), typeclass] end def each_question @question.each {\|name, typeclass\| yield name, typeclass } end def add_answer(name, ttl, data) @answer << [Name.create(name), ttl, data] end def each_answer @answer.each {\|name, ttl, data\| yield name, ttl, data } end def add_authority(name, ttl, data) @authority << [Name.create(name), ttl, data] end def each_authority @authority.each {\|name, ttl, data\| yield name, ttl, data } end def add_additional(name, ttl, data) @additional << [Name.create(name), ttl, data] end def each_additional @additional.each {\|name, ttl, data\| yield name, ttl, data } end def each_resource each_answer {\|name, ttl, data\| yield name, ttl, data} each_authority {\|name, ttl, data\| yield name, ttl, data} each_additional {\|name, ttl, data\| yield name, ttl, data} end def encode return MessageEncoder.new {\|msg\| msg.put_pack('nnnnnn', @id, (@qr & 1) << 15 \| (@opcode & 15) << 11 \| (@aa & 1) << 10 \| (@tc & 1) << 9 \| (@rd & 1) << 8 \| (@ra & 1) << 7 \| (@rcode & 15), @question.length, @answer.length, @authority.length, @additional.length) @question.each {\|q\| name, typeclass = q msg.put_name(name) msg.put_pack('nn', typeclass::TypeValue, typeclass::ClassValue) } [@answer, @authority, @additional].each {\|rr\| rr.each {\|r\| name, ttl, data = r msg.put_name(name) msg.put_pack('nnN', data.class::TypeValue, data.class::ClassValue, ttl) msg.put_length16 {data.encode_rdata(msg)} } } }.to_s end class MessageEncoder # :nodoc: def initialize @data = '' @names = {} yield self end def to_s return @data end def put_bytes(d) @data << d end def put_pack(template, d) @data << d.pack(template) end def put_length16 length_index = @data.length @data << "\0\0" data_start = @data.length yield data_end = @data.length @data[length_index, 2] = [data_end - data_start].pack("n") end def put_string(d) self.put_pack("C", d.length) @data << d end def put_string_list(ds) ds.each {\|d\| self.put_string(d) } end def put_name(d) put_labels(d.to_a) end def put_labels(d) d.each_index {\|i\| domain = d[i..-1] if idx = @names[domain] self.put_pack("n", 0xc000 \| idx) return else @names[domain] = @data.length self.put_label(d[i]) end } @data << "\0" end def put_label(d) self.put_string(d.to_s) end end def Message.decode(m) o = Message.new(0) MessageDecoder.new(m) {\|msg\| id, flag, qdcount, ancount, nscount, arcount = msg.get_unpack('nnnnnn') o.id = id o.qr = (flag >> 15) & 1 o.opcode = (flag >> 11) & 15 o.aa = (flag >> 10) & 1 o.tc = (flag >> 9) & 1 o.rd = (flag >> 8) & 1 o.ra = (flag >> 7) & 1 o.rcode = flag & 15 (1..qdcount).each { name, typeclass = msg.get_question o.add_question(name, typeclass) } (1..ancount).each { name, ttl, data = msg.get_rr o.add_answer(name, ttl, data) } (1..nscount).each { name, ttl, data = msg.get_rr o.add_authority(name, ttl, data) } (1..arcount).each { name, ttl, data = msg.get_rr o.add_additional(name, ttl, data) } } return o end class MessageDecoder # :nodoc: def initialize(data) @data = data @index = 0 @limit = data.length yield self end def inspect "\#<#{self.class}: #{@data[0, @index].inspect} #{@data[@index..-1].inspect}>" end def get_length16 len, = self.get_unpack('n') save_limit = @limit @limit = @index + len d = yield(len) if @index < @limit raise DecodeError.new("junk exists") elsif @limit < @index raise DecodeError.new("limit exceeded") end @limit = save_limit return d end def get_bytes(len = @limit - @index) raise DecodeError.new("limit exceeded") if @limit < @index + len d = @data[@index, len] @index += len return d end def get_unpack(template) len = 0 template.each_byte {\|byte\| byte = "%c" % byte case byte when ?c, ?C len += 1 when ?n len += 2 when ?N len += 4 else raise StandardError.new("unsupported template: '#{byte.chr}' in '#{template}'") end } raise DecodeError.new("limit exceeded") if @limit < @index + len arr = @data.unpack("@#{@index}#{template}") @index += len return arr end def get_string raise DecodeError.new("limit exceeded") if @limit <= @index len = @data[@index].ord raise DecodeError.new("limit exceeded") if @limit < @index + 1 + len d = @data[@index + 1, len] @index += 1 + len return d end def get_string_list strings = [] while @index < @limit strings << self.get_string end strings end def get_name return Name.new(self.get_labels) end def get_labels(limit=nil) limit = @index if !limit \|\| @index < limit d = [] while true raise DecodeError.new("limit exceeded") if @limit <= @index case @data[@index].ord when 0 @index += 1 return d when 192..255 idx = self.get_unpack('n')[0] & 0x3fff if limit <= idx raise DecodeError.new("non-backward name pointer") end save_index = @index @index = idx d += self.get_labels(limit) @index = save_index return d else d << self.get_label end end return d end def get_label return Label::Str.new(self.get_string) end def get_question name = self.get_name type, klass = self.get_unpack("nn") return name, Resource.get_class(type, klass) end def get_rr name = self.get_name type, klass, ttl = self.get_unpack('nnN') typeclass = Resource.get_class(type, klass) res = self.get_length16 { typeclass.decode_rdata self } res.instance_variable_set :@ttl, ttl return name, ttl, res end end end ## # A DNS query abstract class. class Query def encode_rdata(msg) # :nodoc: raise EncodeError.new("#{self.class} is query.") end def self.decode_rdata(msg) # :nodoc: raise DecodeError.new("#{self.class} is query.") end end ## # A DNS resource abstract class. class Resource < Query ## # Remaining Time To Live for this Resource. attr_reader :ttl ClassHash = {} # :nodoc: def encode_rdata(msg) # :nodoc: raise NotImplementedError.new end def self.decode_rdata(msg) # :nodoc: raise NotImplementedError.new end def ==(other) # :nodoc: return false unless self.class == other.class s_ivars = self.instance_variables s_ivars.sort! s_ivars.delete "@ttl" o_ivars = other.instance_variables o_ivars.sort! o_ivars.delete "@ttl" return s_ivars == o_ivars && s_ivars.collect {\|name\| self.instance_variable_get name} == o_ivars.collect {\|name\| other.instance_variable_get name} end def eql?(other) # :nodoc: return self == other end def hash # :nodoc: h = 0 vars = self.instance_variables vars.delete "@ttl" vars.each {\|name\| h ^= self.instance_variable_get(name).hash } return h end def self.get_class(type_value, class_value) # :nodoc: return ClassHash[[type_value, class_value]] \|\| Generic.create(type_value, class_value) end ## # A generic resource abstract class. class Generic < Resource ## # Creates a new generic resource. def initialize(data) @data = data end ## # Data for this generic resource. attr_reader :data def encode_rdata(msg) # :nodoc: msg.put_bytes(data) end def self.decode_rdata(msg) # :nodoc: return self.new(msg.get_bytes) end def self.create(type_value, class_value) # :nodoc: c = Class.new(Generic) c.const_set(:TypeValue, type_value) c.const_set(:ClassValue, class_value) Generic.const_set("Type#{type_value}_Class#{class_value}", c) ClassHash[[type_value, class_value]] = c return c end end ## # Domain Name resource abstract class. class DomainName < Resource ## # Creates a new DomainName from +name+. def initialize(name) @name = name end ## # The name of this DomainName. attr_reader :name def encode_rdata(msg) # :nodoc: msg.put_name(@name) end def self.decode_rdata(msg) # :nodoc: return self.new(msg.get_name) end end # Standard (class generic) RRs ClassValue = nil # :nodoc: ## # An authoritative name server. class NS < DomainName TypeValue = 2 # :nodoc: end ## # The canonical name for an alias. class CNAME < DomainName TypeValue = 5 # :nodoc: end ## # Start Of Authority resource. class SOA < Resource TypeValue = 6 # :nodoc: ## # Creates a new SOA record. See the attr documentation for the # details of each argument. def initialize(mname, rname, serial, refresh, retry_, expire, minimum) @mname = mname @rname = rname @serial = serial @refresh = refresh @retry = retry_ @expire = expire @minimum = minimum end ## # Name of the host where the master zone file for this zone resides. attr_reader :mname ## # The person responsible for this domain name. attr_reader :rname ## # The version number of the zone file. attr_reader :serial ## # How often, in seconds, a secondary name server is to check for # updates from the primary name server. attr_reader :refresh ## # How often, in seconds, a secondary name server is to retry after a # failure to check for a refresh. attr_reader :retry ## # Time in seconds that a secondary name server is to use the data # before refreshing from the primary name server. attr_reader :expire ## # The minimum number of seconds to be used for TTL values in RRs. attr_reader :minimum def encode_rdata(msg) # :nodoc: msg.put_name(@mname) msg.put_name(@rname) msg.put_pack('NNNNN', @serial, @refresh, @retry, @expire, @minimum) end def self.decode_rdata(msg) # :nodoc: mname = msg.get_name rname = msg.get_name serial, refresh, retry_, expire, minimum = msg.get_unpack('NNNNN') return self.new( mname, rname, serial, refresh, retry_, expire, minimum) end end ## # A Pointer to another DNS name. class PTR < DomainName TypeValue = 12 # :nodoc: end ## # Host Information resource. class HINFO < Resource TypeValue = 13 # :nodoc: ## # Creates a new HINFO running +os+ on +cpu+. def initialize(cpu, os) @cpu = cpu @os = os end ## # CPU architecture for this resource. attr_reader :cpu ## # Operating system for this resource. attr_reader :os def encode_rdata(msg) # :nodoc: msg.put_string(@cpu) msg.put_string(@os) end def self.decode_rdata(msg) # :nodoc: cpu = msg.get_string os = msg.get_string return self.new(cpu, os) end end ## # Mailing list or mailbox information. class MINFO < Resource TypeValue = 14 # :nodoc: def initialize(rmailbx, emailbx) @rmailbx = rmailbx @emailbx = emailbx end ## # Domain name responsible for this mail list or mailbox. attr_reader :rmailbx ## # Mailbox to use for error messages related to the mail list or mailbox. attr_reader :emailbx def encode_rdata(msg) # :nodoc: msg.put_name(@rmailbx) msg.put_name(@emailbx) end def self.decode_rdata(msg) # :nodoc: rmailbx = msg.get_string emailbx = msg.get_string return self.new(rmailbx, emailbx) end end ## # Mail Exchanger resource. class MX < Resource TypeValue= 15 # :nodoc: ## # Creates a new MX record with +preference+, accepting mail at # +exchange+. def initialize(preference, exchange) @preference = preference @exchange = exchange end ## # The preference for this MX. attr_reader :preference ## # The host of this MX. attr_reader :exchange def encode_rdata(msg) # :nodoc: msg.put_pack('n', @preference) msg.put_name(@exchange) end def self.decode_rdata(msg) # :nodoc: preference, = msg.get_unpack('n') exchange = msg.get_name return self.new(preference, exchange) end end ## # Unstructured text resource. class TXT < Resource TypeValue = 16 # :nodoc: def initialize(first_string, rest_strings) @strings = [first_string, rest_strings] end ## # Returns an Array of Strings for this TXT record. attr_reader :strings ## # Returns the concatenated string from +strings+. def data @strings.join("") end def encode_rdata(msg) # :nodoc: msg.put_string_list(@strings) end def self.decode_rdata(msg) # :nodoc: strings = msg.get_string_list return self.new(strings) end end ## # A Query type requesting any RR. class ANY < Query TypeValue = 255 # :nodoc: end ClassInsensitiveTypes = [ # :nodoc: NS, CNAME, SOA, PTR, HINFO, MINFO, MX, TXT, ANY ] ## # module IN contains ARPA Internet specific RRs. module IN ClassValue = 1 # :nodoc: ClassInsensitiveTypes.each {\|s\| c = Class.new(s) c.const_set(:TypeValue, s::TypeValue) c.const_set(:ClassValue, ClassValue) ClassHash[[s::TypeValue, ClassValue]] = c self.const_set(s.name.sub(/.::/, ''), c) } ## # IPv4 Address resource class A < Resource TypeValue = 1 ClassValue = IN::ClassValue ClassHash[[TypeValue, ClassValue]] = self # :nodoc: ## # Creates a new A for +address+. def initialize(address) @address = IPv4.create(address) end ## # The Resolv::IPv4 address for this A. attr_reader :address def encode_rdata(msg) # :nodoc: msg.put_bytes(@address.address) end def self.decode_rdata(msg) # :nodoc: return self.new(IPv4.new(msg.get_bytes(4))) end end ## # Well Known Service resource. class WKS < Resource TypeValue = 11 ClassValue = IN::ClassValue ClassHash[[TypeValue, ClassValue]] = self # :nodoc: def initialize(address, protocol, bitmap) @address = IPv4.create(address) @protocol = protocol @bitmap = bitmap end ## # The host these services run on. attr_reader :address ## # IP protocol number for these services. attr_reader :protocol ## # A bit map of enabled services on this host. # # If protocol is 6 (TCP) then the 26th bit corresponds to the SMTP # service (port 25). If this bit is set, then an SMTP server should # be listening on TCP port 25; if zero, SMTP service is not # supported. attr_reader :bitmap def encode_rdata(msg) # :nodoc: msg.put_bytes(@address.address) msg.put_pack("n", @protocol) msg.put_bytes(@bitmap) end def self.decode_rdata(msg) # :nodoc: address = IPv4.new(msg.get_bytes(4)) protocol, = msg.get_unpack("n") bitmap = msg.get_bytes return self.new(address, protocol, bitmap) end end ## # An IPv6 address record. class AAAA < Resource TypeValue = 28 ClassValue = IN::ClassValue ClassHash[[TypeValue, ClassValue]] = self # :nodoc: ## # Creates a new AAAA for +address+. def initialize(address) @address = IPv6.create(address) end ## # The Resolv::IPv6 address for this AAAA. attr_reader :address def encode_rdata(msg) # :nodoc: msg.put_bytes(@address.address) end def self.decode_rdata(msg) # :nodoc: return self.new(IPv6.new(msg.get_bytes(16))) end end ## # SRV resource record defined in RFC 2782 # # These records identify the hostname and port that a service is # available at. class SRV < Resource TypeValue = 33 ClassValue = IN::ClassValue ClassHash[[TypeValue, ClassValue]] = self # :nodoc: # Create a SRV resource record. # # See the documentation for #priority, #weight, #port and #target # for +priority+, +weight+, +port and +target+ respectively. def initialize(priority, weight, port, target) @priority = priority.to_int @weight = weight.to_int @port = port.to_int @target = Name.create(target) end # The priority of this target host. # # A client MUST attempt to contact the target host with the # lowest-numbered priority it can reach; target hosts with the same # priority SHOULD be tried in an order defined by the weight field. # The range is 0-65535. Note that it is not widely implemented and # should be set to zero. attr_reader :priority # A server selection mechanism. # # The weight field specifies a relative weight for entries with the # same priority. Larger weights SHOULD be given a proportionately # higher probability of being selected. The range of this number is # 0-65535. Domain administrators SHOULD use Weight 0 when there # isn't any server selection to do, to make the RR easier to read # for humans (less noisy). Note that it is not widely implemented # and should be set to zero. attr_reader :weight # The port on this target host of this service. # # The range is 0-65535. attr_reader :port # The domain name of the target host. # # A target of "." means that the service is decidedly not available # at this domain. attr_reader :target def encode_rdata(msg) # :nodoc: msg.put_pack("n", @priority) msg.put_pack("n", @weight) msg.put_pack("n", @port) msg.put_name(@target) end def self.decode_rdata(msg) # :nodoc: priority, = msg.get_unpack("n") weight, = msg.get_unpack("n") port, = msg.get_unpack("n") target = msg.get_name return self.new(priority, weight, port, target) end end end end end ## # A Resolv::DNS IPv4 address. class IPv4 ## # Regular expression IPv4 addresses must match. Regex256 = /0 \|1(?:[0-9][0-9]?)? \|2(?:[0-4][0-9]?\|5[0-5]?\|[6-9])? \|[3-9][0-9]?/x Regex = /\A(#{Regex256})\.(#{Regex256})\.(#{Regex256})\.(#{Regex256})\z/ def self.create(arg) case arg when IPv4 return arg when Regex if (0..255) === (a = $1.to_i) && (0..255) === (b = $2.to_i) && (0..255) === (c = $3.to_i) && (0..255) === (d = $4.to_i) return self.new([a, b, c, d].pack("CCCC")) else raise ArgumentError.new("IPv4 address with invalid value: " + arg) end else raise ArgumentError.new("cannot interpret as IPv4 address: #{arg.inspect}") end end def initialize(address) # :nodoc: unless address.kind_of?(String) raise ArgumentError, 'IPv4 address must be a string' end unless address.length == 4 raise ArgumentError, "IPv4 address expects 4 bytes but #{address.length} bytes" end @address = address end ## # A String representation of this IPv4 address. ## # The raw IPv4 address as a String. attr_reader :address def to_s # :nodoc: return sprintf("%d.%d.%d.%d", @address.unpack("CCCC")) end def inspect # :nodoc: return "#<#{self.class} #{self.to_s}>" end ## # Turns this IPv4 address into a Resolv::DNS::Name. def to_name return DNS::Name.create( '%d.%d.%d.%d.in-addr.arpa.' % @address.unpack('CCCC').reverse) end def ==(other) # :nodoc: return @address == other.address end def eql?(other) # :nodoc: return self == other end def hash # :nodoc: return @address.hash end end ## # A Resolv::DNS IPv6 address. class IPv6 ## # IPv6 address format a:b:c:d:e:f:g:h Regex_8Hex = /\A (?:[0-9A-Fa-f]{1,4}:){7} [0-9A-Fa-f]{1,4} \z/x ## # Compressed IPv6 address format a::b Regex_CompressedHex = /\A ((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4}))?) :: ((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4}))?) \z/x ## # IPv4 mapped IPv6 address format a:b:c:d:e:f:w.x.y.z Regex_6Hex4Dec = /\A ((?:[0-9A-Fa-f]{1,4}:){6,6}) (\d+)\.(\d+)\.(\d+)\.(\d+) \z/x ## # Compressed IPv4 mapped IPv6 address format a::b:w.x.y.z Regex_CompressedHex4Dec = /\A ((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4}))?) :: ((?:[0-9A-Fa-f]{1,4}:)) (\d+)\.(\d+)\.(\d+)\.(\d+) \z/x ## # A composite IPv6 address Regexp. Regex = / (?:#{Regex_8Hex}) \| (?:#{Regex_CompressedHex}) \| (?:#{Regex_6Hex4Dec}) \| (?:#{Regex_CompressedHex4Dec})/x ## # Creates a new IPv6 address from +arg+ which may be: # # IPv6:: returns +arg+. # String:: +arg+ must match one of the IPv6::Regex* constants def self.create(arg) case arg when IPv6 return arg when String address = '' if Regex_8Hex =~ arg arg.scan(/[0-9A-Fa-f]+/) {\|hex\| address << [hex.hex].pack('n')} elsif Regex_CompressedHex =~ arg prefix = $1 suffix = $2 a1 = '' a2 = '' prefix.scan(/[0-9A-Fa-f]+/) {\|hex\| a1 << [hex.hex].pack('n')} suffix.scan(/[0-9A-Fa-f]+/) {\|hex\| a2 << [hex.hex].pack('n')} omitlen = 16 - a1.length - a2.length address << a1 << "\0" * omitlen << a2 elsif Regex_6Hex4Dec =~ arg prefix, a, b, c, d = $1, $2.to_i, $3.to_i, $4.to_i, $5.to_i if (0..255) === a && (0..255) === b && (0..255) === c && (0..255) === d prefix.scan(/[0-9A-Fa-f]+/) {\|hex\| address << [hex.hex].pack('n')} address << [a, b, c, d].pack('CCCC') else raise ArgumentError.new("not numeric IPv6 address: " + arg) end elsif Regex_CompressedHex4Dec =~ arg prefix, suffix, a, b, c, d = $1, $2, $3.to_i, $4.to_i, $5.to_i, $6.to_i if (0..255) === a && (0..255) === b && (0..255) === c && (0..255) === d a1 = '' a2 = '' prefix.scan(/[0-9A-Fa-f]+/) {\|hex\| a1 << [hex.hex].pack('n')} suffix.scan(/[0-9A-Fa-f]+/) {\|hex\| a2 << [hex.hex].pack('n')} omitlen = 12 - a1.length - a2.length address << a1 << "\0" * omitlen << a2 << [a, b, c, d].pack('CCCC') else raise ArgumentError.new("not numeric IPv6 address: " + arg) end else raise ArgumentError.new("not numeric IPv6 address: " + arg) end return IPv6.new(address) else raise ArgumentError.new("cannot interpret as IPv6 address: #{arg.inspect}") end end def initialize(address) # :nodoc: unless address.kind_of?(String) && address.length == 16 raise ArgumentError.new('IPv6 address must be 16 bytes') end @address = address end ## # The raw IPv6 address as a String. attr_reader :address def to_s # :nodoc: address = sprintf("%X:%X:%X:%X:%X:%X:%X:%X", *@address.unpack("nnnnnnnn")) unless address.sub!(/(^\|:)0(:0)+(:\|$)/, '::') address.sub!(/(^\|:)0(:\|$)/, '::') end return address end def inspect # :nodoc: return "#<#{self.class} #{self.to_s}>" end ## # Turns this IPv6 address into a Resolv::DNS::Name. #-- # ip6.arpa should be searched too. [RFC3152] def to_name return DNS::Name.new( @address.unpack("H32")[0].split(//).reverse + ['ip6', 'arpa']) end def ==(other) # :nodoc: return @address == other.address end def eql?(other) # :nodoc: return self == other end def hash # :nodoc: return @address.hash end end ## # Default resolver to use for Resolv class methods. DefaultResolver = self.new ## # Address Regexp to use for matching IP addresses. AddressRegex = /(?:#{IPv4::Regex})\|(?:#{IPv6::Regex})/ end Back

Edit File : resolv.rb | Size : 59.91 KB

require 'socket'
require 'fcntl'
require 'timeout'
require 'thread'

begin
  require 'securerandom'
rescue LoadError
end

# Resolv is a thread-aware DNS resolver library written in Ruby.  Resolv can
# handle multiple DNS requests concurrently without blocking the entire ruby
# interpreter.
#
# See also resolv-replace.rb to replace the libc resolver with Resolv.
#
# Resolv can look up various DNS resources using the DNS module directly.
#
# Examples:
#
#   p Resolv.getaddress "www.ruby-lang.org"
#   p Resolv.getname "210.251.121.214"
#
#   Resolv::DNS.open do |dns|
#     ress = dns.getresources "www.ruby-lang.org", Resolv::DNS::Resource::IN::A
#     p ress.map { |r| r.address }
#     ress = dns.getresources "ruby-lang.org", Resolv::DNS::Resource::IN::MX
#     p ress.map { |r| [r.exchange.to_s, r.preference] }
#   end
#
#
# == Bugs
#
# * NIS is not supported.
# * /etc/nsswitch.conf is not supported.

class Resolv

##
  # Looks up the first IP address for +name+.

def self.getaddress(name)
    DefaultResolver.getaddress(name)
  end

##
  # Looks up all IP address for +name+.

def self.getaddresses(name)
    DefaultResolver.getaddresses(name)
  end

##
  # Iterates over all IP addresses for +name+.

def self.each_address(name, &block)
    DefaultResolver.each_address(name, &block)
  end

##
  # Looks up the hostname of +address+.

def self.getname(address)
    DefaultResolver.getname(address)
  end

##
  # Looks up all hostnames for +address+.

def self.getnames(address)
    DefaultResolver.getnames(address)
  end

##
  # Iterates over all hostnames for +address+.

def self.each_name(address, &proc)
    DefaultResolver.each_name(address, &proc)
  end

##
  # Creates a new Resolv using +resolvers+.

def initialize(resolvers=[Hosts.new, DNS.new])
    @resolvers = resolvers
  end

##
  # Looks up the first IP address for +name+.

def getaddress(name)
    each_address(name) {|address| return address}
    raise ResolvError.new("no address for #{name}")
  end

##
  # Looks up all IP address for +name+.

def getaddresses(name)
    ret = []
    each_address(name) {|address| ret << address}
    return ret
  end

##
  # Iterates over all IP addresses for +name+.

def each_address(name)
    if AddressRegex =~ name
      yield name
      return
    end
    yielded = false
    @resolvers.each {|r|
      r.each_address(name) {|address|
        yield address.to_s
        yielded = true
      }
      return if yielded
    }
  end

##
  # Looks up the hostname of +address+.

def getname(address)
    each_name(address) {|name| return name}
    raise ResolvError.new("no name for #{address}")
  end

##
  # Looks up all hostnames for +address+.

def getnames(address)
    ret = []
    each_name(address) {|name| ret << name}
    return ret
  end

##
  # Iterates over all hostnames for +address+.

def each_name(address)
    yielded = false
    @resolvers.each {|r|
      r.each_name(address) {|name|
        yield name.to_s
        yielded = true
      }
      return if yielded
    }
  end

##
  # Indicates a failure to resolve a name or address.

class ResolvError < StandardError; end

##
  # Indicates a timeout resolving a name or address.

class ResolvTimeout < TimeoutError; end

##
  # Resolv::Hosts is a hostname resolver that uses the system hosts file.

class Hosts
    if /mswin|mingw|bccwin/ =~ RUBY_PLATFORM
      require 'win32/resolv'
      DefaultFileName = Win32::Resolv.get_hosts_path
    else
      DefaultFileName = '/etc/hosts'
    end

##
    # Creates a new Resolv::Hosts, using +filename+ for its data source.

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

def lazy_initialize # :nodoc:
      @mutex.synchronize {
        unless @initialized
          @name2addr = {}
          @addr2name = {}
          open(@filename, 'rb') {|f|
            f.each {|line|
              line.sub!(/#.*/, '')
              addr, hostname, *aliases = line.split(/\s+/)
              next unless addr
              addr.untaint
              hostname.untaint
              @addr2name[addr] = [] unless @addr2name.include? addr
              @addr2name[addr] << hostname
              @addr2name[addr] += aliases
              @name2addr[hostname] = [] unless @name2addr.include? hostname
              @name2addr[hostname] << addr
              aliases.each {|n|
                n.untaint
                @name2addr[n] = [] unless @name2addr.include? n
                @name2addr[n] << addr
              }
            }
          }
          @name2addr.each {|name, arr| arr.reverse!}
          @initialized = true
        end
      }
      self
    end

##
    # Gets the IP address of +name+ from the hosts file.

def getaddress(name)
      each_address(name) {|address| return address}
      raise ResolvError.new("#{@filename} has no name: #{name}")
    end

##
    # Gets all IP addresses for +name+ from the hosts file.

def getaddresses(name)
      ret = []
      each_address(name) {|address| ret << address}
      return ret
    end

##
    # Iterates over all IP addresses for +name+ retrieved from the hosts file.

def each_address(name, &proc)
      lazy_initialize
      if @name2addr.include?(name)
        @name2addr[name].each(&proc)
      end
    end

##
    # Gets the hostname of +address+ from the hosts file.

def getname(address)
      each_name(address) {|name| return name}
      raise ResolvError.new("#{@filename} has no address: #{address}")
    end

##
    # Gets all hostnames for +address+ from the hosts file.

def getnames(address)
      ret = []
      each_name(address) {|name| ret << name}
      return ret
    end

##
    # Iterates over all hostnames for +address+ retrieved from the hosts file.

def each_name(address, &proc)
      lazy_initialize
      if @addr2name.include?(address)
        @addr2name[address].each(&proc)
      end
    end
  end

##
  # Resolv::DNS is a DNS stub resolver.
  #
  # Information taken from the following places:
  #
  # * STD0013
  # * RFC 1035
  # * ftp://ftp.isi.edu/in-notes/iana/assignments/dns-parameters
  # * etc.

class DNS

##
    # Default DNS Port

Port = 53

##
    # Default DNS UDP packet size

UDPSize = 512

##
    # Creates a new DNS resolver.  See Resolv::DNS.new for argument details.
    #
    # Yields the created DNS resolver to the block, if given, otherwise
    # returns it.

def self.open(*args)
      dns = new(*args)
      return dns unless block_given?
      begin
        yield dns
      ensure
        dns.close
      end
    end

##
    # Creates a new DNS resolver.
    #
    # +config_info+ can be:
    #
    # nil:: Uses /etc/resolv.conf.
    # String:: Path to a file using /etc/resolv.conf's format.
    # Hash:: Must contain :nameserver, :search and :ndots keys.
    # :nameserver_port can be used to specify port number of nameserver address.
    #
    # The value of :nameserver should be an address string or
    # an array of address strings.
    # - :nameserver => '8.8.8.8'
    # - :nameserver => ['8.8.8.8', '8.8.4.4']
    #
    # The value of :nameserver_port should be an array of
    # pair of nameserver address and port number.
    # - :nameserver_port => [['8.8.8.8', 53], ['8.8.4.4', 53]]
    #
    # Example:
    #
    #   Resolv::DNS.new(:nameserver => ['210.251.121.21'],
    #                   :search => ['ruby-lang.org'],
    #                   :ndots => 1)

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

def lazy_initialize # :nodoc:
      @mutex.synchronize {
        unless @initialized
          @config.lazy_initialize
          @initialized = true
        end
      }
      self
    end

##
    # Closes the DNS resolver.

def close
      @mutex.synchronize {
        if @initialized
          @initialized = false
        end
      }
    end

##
    # Gets the IP address of +name+ from the DNS resolver.
    #
    # +name+ can be a Resolv::DNS::Name or a String.  Retrieved address will
    # be a Resolv::IPv4 or Resolv::IPv6

def getaddress(name)
      each_address(name) {|address| return address}
      raise ResolvError.new("DNS result has no information for #{name}")
    end

##
    # Gets all IP addresses for +name+ from the DNS resolver.
    #
    # +name+ can be a Resolv::DNS::Name or a String.  Retrieved addresses will
    # be a Resolv::IPv4 or Resolv::IPv6

def getaddresses(name)
      ret = []
      each_address(name) {|address| ret << address}
      return ret
    end

##
    # Iterates over all IP addresses for +name+ retrieved from the DNS
    # resolver.
    #
    # +name+ can be a Resolv::DNS::Name or a String.  Retrieved addresses will
    # be a Resolv::IPv4 or Resolv::IPv6

def each_address(name)
      each_resource(name, Resource::IN::A) {|resource| yield resource.address}
      if use_ipv6?
        each_resource(name, Resource::IN::AAAA) {|resource| yield resource.address}
      end
    end

def use_ipv6? # :nodoc:
      begin
        list = Socket.ip_address_list
      rescue NotImplementedError
        return true
      end
      list.any? {|a| a.ipv6? && !a.ipv6_loopback? && !a.ipv6_linklocal? }
    end
    private :use_ipv6?

##
    # Gets the hostname for +address+ from the DNS resolver.
    #
    # +address+ must be a Resolv::IPv4, Resolv::IPv6 or a String.  Retrieved
    # name will be a Resolv::DNS::Name.

def getname(address)
      each_name(address) {|name| return name}
      raise ResolvError.new("DNS result has no information for #{address}")
    end

##
    # Gets all hostnames for +address+ from the DNS resolver.
    #
    # +address+ must be a Resolv::IPv4, Resolv::IPv6 or a String.  Retrieved
    # names will be Resolv::DNS::Name instances.

def getnames(address)
      ret = []
      each_name(address) {|name| ret << name}
      return ret
    end

##
    # Iterates over all hostnames for +address+ retrieved from the DNS
    # resolver.
    #
    # +address+ must be a Resolv::IPv4, Resolv::IPv6 or a String.  Retrieved
    # names will be Resolv::DNS::Name instances.

def each_name(address)
      case address
      when Name
        ptr = address
      when IPv4::Regex
        ptr = IPv4.create(address).to_name
      when IPv6::Regex
        ptr = IPv6.create(address).to_name
      else
        raise ResolvError.new("cannot interpret as address: #{address}")
      end
      each_resource(ptr, Resource::IN::PTR) {|resource| yield resource.name}
    end

##
    # Look up the +typeclass+ DNS resource of +name+.
    #
    # +name+ must be a Resolv::DNS::Name or a String.
    #
    # +typeclass+ should be one of the following:
    #
    # * Resolv::DNS::Resource::IN::A
    # * Resolv::DNS::Resource::IN::AAAA
    # * Resolv::DNS::Resource::IN::ANY
    # * Resolv::DNS::Resource::IN::CNAME
    # * Resolv::DNS::Resource::IN::HINFO
    # * Resolv::DNS::Resource::IN::MINFO
    # * Resolv::DNS::Resource::IN::MX
    # * Resolv::DNS::Resource::IN::NS
    # * Resolv::DNS::Resource::IN::PTR
    # * Resolv::DNS::Resource::IN::SOA
    # * Resolv::DNS::Resource::IN::TXT
    # * Resolv::DNS::Resource::IN::WKS
    #
    # Returned resource is represented as a Resolv::DNS::Resource instance,
    # i.e. Resolv::DNS::Resource::IN::A.

def getresource(name, typeclass)
      each_resource(name, typeclass) {|resource| return resource}
      raise ResolvError.new("DNS result has no information for #{name}")
    end

##
    # Looks up all +typeclass+ DNS resources for +name+.  See #getresource for
    # argument details.

def getresources(name, typeclass)
      ret = []
      each_resource(name, typeclass) {|resource| ret << resource}
      return ret
    end

##
    # Iterates over all +typeclass+ DNS resources for +name+.  See
    # #getresource for argument details.

def each_resource(name, typeclass, &proc)
      lazy_initialize
      requester = make_udp_requester
      senders = {}
      begin
        @config.resolv(name) {|candidate, tout, nameserver, port|
          msg = Message.new
          msg.rd = 1
          msg.add_question(candidate, typeclass)
          unless sender = senders[[candidate, nameserver, port]]
            sender = requester.sender(msg, candidate, nameserver, port)
            next if !sender
            senders[[candidate, nameserver, port]] = sender
          end
          reply, reply_name = requester.request(sender, tout)
          case reply.rcode
          when RCode::NoError
            if reply.tc == 1 and not Requester::TCP === requester
              requester.close
              # Retry via TCP:
              requester = make_tcp_requester(nameserver, port)
              senders = {}
              # This will use TCP for all remaining candidates (assuming the
              # current candidate does not already respond successfully via
              # TCP).  This makes sense because we already know the full
              # response will not fit in an untruncated UDP packet.
              redo
            else
              extract_resources(reply, reply_name, typeclass, &proc)
            end
            return
          when RCode::NXDomain
            raise Config::NXDomain.new(reply_name.to_s)
          else
            raise Config::OtherResolvError.new(reply_name.to_s)
          end
        }
      ensure
        requester.close
      end
    end

def make_udp_requester # :nodoc:
      nameserver_port = @config.nameserver_port
      if nameserver_port.length == 1
        Requester::ConnectedUDP.new(*nameserver_port[0])
      else
        Requester::UnconnectedUDP.new(*nameserver_port)
      end
    end

def make_tcp_requester(host, port) # :nodoc:
      return Requester::TCP.new(host, port)
    end

def extract_resources(msg, name, typeclass) # :nodoc:
      if typeclass < Resource::ANY
        n0 = Name.create(name)
        msg.each_answer {|n, ttl, data|
          yield data if n0 == n
        }
      end
      yielded = false
      n0 = Name.create(name)
      msg.each_answer {|n, ttl, data|
        if n0 == n
          case data
          when typeclass
            yield data
            yielded = true
          when Resource::CNAME
            n0 = data.name
          end
        end
      }
      return if yielded
      msg.each_answer {|n, ttl, data|
        if n0 == n
          case data
          when typeclass
            yield data
          end
        end
      }
    end

if defined? SecureRandom
      def self.random(arg) # :nodoc:
        begin
          SecureRandom.random_number(arg)
        rescue NotImplementedError
          rand(arg)
        end
      end
    else
      def self.random(arg) # :nodoc:
        rand(arg)
      end
    end

def self.rangerand(range) # :nodoc:
      base = range.begin
      len = range.end - range.begin
      if !range.exclude_end?
        len += 1
      end
      base + random(len)
    end

RequestID = {} # :nodoc:
    RequestIDMutex = Mutex.new # :nodoc:

def self.allocate_request_id(host, port) # :nodoc:
      id = nil
      RequestIDMutex.synchronize {
        h = (RequestID[[host, port]] ||= {})
        begin
          id = rangerand(0x0000..0xffff)
        end while h[id]
        h[id] = true
      }
      id
    end

def self.free_request_id(host, port, id) # :nodoc:
      RequestIDMutex.synchronize {
        key = [host, port]
        if h = RequestID[key]
          h.delete id
          if h.empty?
            RequestID.delete key
          end
        end
      }
    end

def self.bind_random_port(udpsock, bind_host="0.0.0.0") # :nodoc:
      begin
        port = rangerand(1024..65535)
        udpsock.bind(bind_host, port)
      rescue Errno::EADDRINUSE
        retry
      end
    end

class Requester # :nodoc:
      def initialize
        @senders = {}
        @socks = nil
      end

def request(sender, tout)
        timelimit = Time.now + tout
        sender.send
        while true
          now = Time.now
          timeout = timelimit - now
          if timeout <= 0
            raise ResolvTimeout
          end
          select_result = IO.select(@socks, nil, nil, timeout)
          if !select_result
            raise ResolvTimeout
          end
          begin
            reply, from = recv_reply(select_result[0])
          rescue Errno::ECONNREFUSED, # GNU/Linux, FreeBSD
                 Errno::ECONNRESET # Windows
            # No name server running on the server?
            # Don't wait anymore.
            raise ResolvTimeout
          end
          begin
            msg = Message.decode(reply)
          rescue DecodeError
            next # broken DNS message ignored
          end
          if s = @senders[[from,msg.id]]
            break
          else
            # unexpected DNS message ignored
          end
        end
        return msg, s.data
      end

def close
        socks = @socks
        @socks = nil
        if socks
          socks.each {|sock| sock.close }
        end
      end

class Sender # :nodoc:
        def initialize(msg, data, sock)
          @msg = msg
          @data = data
          @sock = sock
        end
      end

class UnconnectedUDP < Requester # :nodoc:
        def initialize(*nameserver_port)
          super()
          @nameserver_port = nameserver_port
          @socks_hash = {}
          @socks = []
          nameserver_port.each {|host, port|
            if host.index(':')
              bind_host = "::"
              af = Socket::AF_INET6
            else
              bind_host = "0.0.0.0"
              af = Socket::AF_INET
            end
            next if @socks_hash[bind_host]
            begin
              sock = UDPSocket.new(af)
            rescue Errno::EAFNOSUPPORT
              next # The kernel doesn't support the address family.
            end
            sock.do_not_reverse_lookup = true
            sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD
            DNS.bind_random_port(sock, bind_host)
            @socks << sock
            @socks_hash[bind_host] = sock
          }
        end

def recv_reply(readable_socks)
          reply, from = readable_socks[0].recvfrom(UDPSize)
          return reply, [from[3],from[1]]
        end

def sender(msg, data, host, port=Port)
          sock = @socks_hash[host.index(':') ? "::" : "0.0.0.0"]
          return nil if !sock
          service = [host, port]
          id = DNS.allocate_request_id(host, port)
          request = msg.encode
          request[0,2] = [id].pack('n')
          return @senders[[service, id]] =
            Sender.new(request, data, sock, host, port)
        end

def close
          super
          @senders.each_key {|service, id|
            DNS.free_request_id(service[0], service[1], id)
          }
        end

class Sender < Requester::Sender # :nodoc:
          def initialize(msg, data, sock, host, port)
            super(msg, data, sock)
            @host = host
            @port = port
          end
          attr_reader :data

def send
            raise "@sock is nil." if @sock.nil?
            @sock.send(@msg, 0, @host, @port)
          end
        end
      end

class ConnectedUDP < Requester # :nodoc:
        def initialize(host, port=Port)
          super()
          @host = host
          @port = port
          is_ipv6 = host.index(':')
          sock = UDPSocket.new(is_ipv6 ? Socket::AF_INET6 : Socket::AF_INET)
          @socks = [sock]
          sock.do_not_reverse_lookup = true
          sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD
          DNS.bind_random_port(sock, is_ipv6 ? "::" : "0.0.0.0")
          sock.connect(host, port)
        end

def recv_reply(readable_socks)
          reply = readable_socks[0].recv(UDPSize)
          return reply, nil
        end

def sender(msg, data, host=@host, port=@port)
          unless host == @host && port == @port
            raise RequestError.new("host/port don't match: #{host}:#{port}")
          end
          id = DNS.allocate_request_id(@host, @port)
          request = msg.encode
          request[0,2] = [id].pack('n')
          return @senders[[nil,id]] = Sender.new(request, data, @socks[0])
        end

def close
          super
          @senders.each_key {|from, id|
            DNS.free_request_id(@host, @port, id)
          }
        end

class Sender < Requester::Sender # :nodoc:
          def send
            raise "@sock is nil." if @sock.nil?
            @sock.send(@msg, 0)
          end
          attr_reader :data
        end
      end

class TCP < Requester # :nodoc:
        def initialize(host, port=Port)
          super()
          @host = host
          @port = port
          sock = TCPSocket.new(@host, @port)
          @socks = [sock]
          sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD
          @senders = {}
        end

def recv_reply(readable_socks)
          len = readable_socks[0].read(2).unpack('n')[0]
          reply = @socks[0].read(len)
          return reply, nil
        end

def sender(msg, data, host=@host, port=@port)
          unless host == @host && port == @port
            raise RequestError.new("host/port don't match: #{host}:#{port}")
          end
          id = DNS.allocate_request_id(@host, @port)
          request = msg.encode
          request[0,2] = [request.length, id].pack('nn')
          return @senders[[nil,id]] = Sender.new(request, data, @socks[0])
        end

class Sender < Requester::Sender # :nodoc:
          def send
            @sock.print(@msg)
            @sock.flush
          end
          attr_reader :data
        end

def close
          super
          @senders.each_key {|from,id|
            DNS.free_request_id(@host, @port, id)
          }
        end
      end

##
      # Indicates a problem with the DNS request.

class RequestError < StandardError
      end
    end

class Config # :nodoc:
      def initialize(config_info=nil)
        @mutex = Mutex.new
        @config_info = config_info
        @initialized = nil
      end

def Config.parse_resolv_conf(filename)
        nameserver = []
        search = nil
        ndots = 1
        open(filename, 'rb') {|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

def Config.default_config_hash(filename="/etc/resolv.conf")
        if File.exist? filename
          config_hash = Config.parse_resolv_conf(filename)
        else
          if /mswin|cygwin|mingw|bccwin/ =~ RUBY_PLATFORM
            require 'win32/resolv'
            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

def lazy_initialize
        @mutex.synchronize {
          unless @initialized
            @nameserver_port = []
            @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
            if config_hash.include? :nameserver
              @nameserver_port = config_hash[:nameserver].map {|ns| [ns, Port] }
            end
            if config_hash.include? :nameserver_port
              @nameserver_port = config_hash[:nameserver_port].map {|ns, port| [ns, (port || Port)] }
            end
            @search = config_hash[:search] if config_hash.include? :search
            @ndots = config_hash[:ndots] if config_hash.include? :ndots

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

if !@nameserver_port.kind_of?(Array) ||
               @nameserver_port.any? {|ns_port|
                  !(Array === ns_port) ||
                  ns_port.length != 2
                  !(String === ns_port[0]) ||
                  !(Integer === ns_port[1])
               }
              raise ArgumentError.new("invalid nameserver config: #{@nameserver_port.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

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

def nameserver_port
        @nameserver_port
      end

def generate_candidates(name)
        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

InitialTimeout = 5

def generate_timeouts
        ts = [InitialTimeout]
        ts << ts[-1] * 2 / @nameserver_port.length
        ts << ts[-1] * 2
        ts << ts[-1] * 2
        return ts
      end

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

##
      # Indicates no such domain was found.

class NXDomain < ResolvError
      end

##
      # Indicates some other unhandled resolver error was encountered.

class OtherResolvError < ResolvError
      end
    end

module OpCode # :nodoc:
      Query = 0
      IQuery = 1
      Status = 2
      Notify = 4
      Update = 5
    end

module RCode # :nodoc:
      NoError = 0
      FormErr = 1
      ServFail = 2
      NXDomain = 3
      NotImp = 4
      Refused = 5
      YXDomain = 6
      YXRRSet = 7
      NXRRSet = 8
      NotAuth = 9
      NotZone = 10
      BADVERS = 16
      BADSIG = 16
      BADKEY = 17
      BADTIME = 18
      BADMODE = 19
      BADNAME = 20
      BADALG = 21
    end

##
    # Indicates that the DNS response was unable to be decoded.

class DecodeError < StandardError
    end

##
    # Indicates that the DNS request was unable to be encoded.

class EncodeError < StandardError
    end

module Label # :nodoc:
      def self.split(arg)
        labels = []
        arg.scan(/[^\.]+/) {labels << Str.new($&)}
        return labels
      end

class Str # :nodoc:
        def initialize(string)
          @string = string
          @downcase = string.downcase
        end
        attr_reader :string, :downcase

def to_s
          return @string
        end

def inspect
          return "#<#{self.class} #{self.to_s}>"
        end

def ==(other)
          return @downcase == other.downcase
        end

def eql?(other)
          return self == other
        end

def hash
          return @downcase.hash
        end
      end
    end

##
    # A representation of a DNS name.

class Name

##
      # Creates a new DNS name from +arg+.  +arg+ can be:
      #
      # Name:: returns +arg+.
      # String:: Creates a new Name.

def self.create(arg)
        case arg
        when Name
          return arg
        when String
          return Name.new(Label.split(arg), /\.\z/ =~ arg ? true : false)
        else
          raise ArgumentError.new("cannot interpret as DNS name: #{arg.inspect}")
        end
      end

def initialize(labels, absolute=true) # :nodoc:
        @labels = labels
        @absolute = absolute
      end

def inspect # :nodoc:
        "#<#{self.class}: #{self.to_s}#{@absolute ? '.' : ''}>"
      end

##
      # True if this name is absolute.

def absolute?
        return @absolute
      end

def ==(other) # :nodoc:
        return false unless Name === other
        return @labels.join == other.to_a.join && @absolute == other.absolute?
      end

alias eql? == # :nodoc:

##
      # Returns true if +other+ is a subdomain.
      #
      # Example:
      #
      #   domain = Resolv::DNS::Name.create("y.z")
      #   p Resolv::DNS::Name.create("w.x.y.z").subdomain_of?(domain) #=> true
      #   p Resolv::DNS::Name.create("x.y.z").subdomain_of?(domain) #=> true
      #   p Resolv::DNS::Name.create("y.z").subdomain_of?(domain) #=> false
      #   p Resolv::DNS::Name.create("z").subdomain_of?(domain) #=> false
      #   p Resolv::DNS::Name.create("x.y.z.").subdomain_of?(domain) #=> false
      #   p Resolv::DNS::Name.create("w.z").subdomain_of?(domain) #=> false
      #

def subdomain_of?(other)
        raise ArgumentError, "not a domain name: #{other.inspect}" unless Name === other
        return false if @absolute != other.absolute?
        other_len = other.length
        return false if @labels.length <= other_len
        return @labels[-other_len, other_len] == other.to_a
      end

def hash # :nodoc:
        return @labels.hash ^ @absolute.hash
      end

def to_a # :nodoc:
        return @labels
      end

def length # :nodoc:
        return @labels.length
      end

def [](i) # :nodoc:
        return @labels[i]
      end

##
      # returns the domain name as a string.
      #
      # The domain name doesn't have a trailing dot even if the name object is
      # absolute.
      #
      # Example:
      #
      #   p Resolv::DNS::Name.create("x.y.z.").to_s #=> "x.y.z"
      #   p Resolv::DNS::Name.create("x.y.z").to_s #=> "x.y.z"

def to_s
        return @labels.join('.')
      end
    end

class Message # :nodoc:
      @@identifier = -1

def initialize(id = (@@identifier += 1) & 0xffff)
        @id = id
        @qr = 0
        @opcode = 0
        @aa = 0
        @tc = 0
        @rd = 0 # recursion desired
        @ra = 0 # recursion available
        @rcode = 0
        @question = []
        @answer = []
        @authority = []
        @additional = []
      end

attr_accessor :id, :qr, :opcode, :aa, :tc, :rd, :ra, :rcode
      attr_reader :question, :answer, :authority, :additional

def ==(other)
        return @id == other.id &&
               @qr == other.qr &&
               @opcode == other.opcode &&
               @aa == other.aa &&
               @tc == other.tc &&
               @rd == other.rd &&
               @ra == other.ra &&
               @rcode == other.rcode &&
               @question == other.question &&
               @answer == other.answer &&
               @authority == other.authority &&
               @additional == other.additional
      end

def add_question(name, typeclass)
        @question << [Name.create(name), typeclass]
      end

def each_question
        @question.each {|name, typeclass|
          yield name, typeclass
        }
      end

def add_answer(name, ttl, data)
        @answer << [Name.create(name), ttl, data]
      end

def each_answer
        @answer.each {|name, ttl, data|
          yield name, ttl, data
        }
      end

def add_authority(name, ttl, data)
        @authority << [Name.create(name), ttl, data]
      end

def each_authority
        @authority.each {|name, ttl, data|
          yield name, ttl, data
        }
      end

def add_additional(name, ttl, data)
        @additional << [Name.create(name), ttl, data]
      end

def each_additional
        @additional.each {|name, ttl, data|
          yield name, ttl, data
        }
      end

def each_resource
        each_answer {|name, ttl, data| yield name, ttl, data}
        each_authority {|name, ttl, data| yield name, ttl, data}
        each_additional {|name, ttl, data| yield name, ttl, data}
      end

def encode
        return MessageEncoder.new {|msg|
          msg.put_pack('nnnnnn',
            @id,
            (@qr & 1) << 15 |
            (@opcode & 15) << 11 |
            (@aa & 1) << 10 |
            (@tc & 1) << 9 |
            (@rd & 1) << 8 |
            (@ra & 1) << 7 |
            (@rcode & 15),
            @question.length,
            @answer.length,
            @authority.length,
            @additional.length)
          @question.each {|q|
            name, typeclass = q
            msg.put_name(name)
            msg.put_pack('nn', typeclass::TypeValue, typeclass::ClassValue)
          }
          [@answer, @authority, @additional].each {|rr|
            rr.each {|r|
              name, ttl, data = r
              msg.put_name(name)
              msg.put_pack('nnN', data.class::TypeValue, data.class::ClassValue, ttl)
              msg.put_length16 {data.encode_rdata(msg)}
            }
          }
        }.to_s
      end

class MessageEncoder # :nodoc:
        def initialize
          @data = ''
          @names = {}
          yield self
        end

def to_s
          return @data
        end

def put_bytes(d)
          @data << d
        end

def put_pack(template, *d)
          @data << d.pack(template)
        end

def put_length16
          length_index = @data.length
          @data << "\0\0"
          data_start = @data.length
          yield
          data_end = @data.length
          @data[length_index, 2] = [data_end - data_start].pack("n")
        end

def put_string(d)
          self.put_pack("C", d.length)
          @data << d
        end

def put_string_list(ds)
          ds.each {|d|
            self.put_string(d)
          }
        end

def put_name(d)
          put_labels(d.to_a)
        end

def put_labels(d)
          d.each_index {|i|
            domain = d[i..-1]
            if idx = @names[domain]
              self.put_pack("n", 0xc000 | idx)
              return
            else
              @names[domain] = @data.length
              self.put_label(d[i])
            end
          }
          @data << "\0"
        end

def put_label(d)
          self.put_string(d.to_s)
        end
      end

def Message.decode(m)
        o = Message.new(0)
        MessageDecoder.new(m) {|msg|
          id, flag, qdcount, ancount, nscount, arcount =
            msg.get_unpack('nnnnnn')
          o.id = id
          o.qr = (flag >> 15) & 1
          o.opcode = (flag >> 11) & 15
          o.aa = (flag >> 10) & 1
          o.tc = (flag >> 9) & 1
          o.rd = (flag >> 8) & 1
          o.ra = (flag >> 7) & 1
          o.rcode = flag & 15
          (1..qdcount).each {
            name, typeclass = msg.get_question
            o.add_question(name, typeclass)
          }
          (1..ancount).each {
            name, ttl, data = msg.get_rr
            o.add_answer(name, ttl, data)
          }
          (1..nscount).each {
            name, ttl, data = msg.get_rr
            o.add_authority(name, ttl, data)
          }
          (1..arcount).each {
            name, ttl, data = msg.get_rr
            o.add_additional(name, ttl, data)
          }
        }
        return o
      end

class MessageDecoder # :nodoc:
        def initialize(data)
          @data = data
          @index = 0
          @limit = data.length
          yield self
        end

def inspect
          "\#<#{self.class}: #{@data[0, @index].inspect} #{@data[@index..-1].inspect}>"
        end

def get_length16
          len, = self.get_unpack('n')
          save_limit = @limit
          @limit = @index + len
          d = yield(len)
          if @index < @limit
            raise DecodeError.new("junk exists")
          elsif @limit < @index
            raise DecodeError.new("limit exceeded")
          end
          @limit = save_limit
          return d
        end

def get_bytes(len = @limit - @index)
          raise DecodeError.new("limit exceeded") if @limit < @index + len
          d = @data[@index, len]
          @index += len
          return d
        end

def get_unpack(template)
          len = 0
          template.each_byte {|byte|
            byte = "%c" % byte
            case byte
            when ?c, ?C
              len += 1
            when ?n
              len += 2
            when ?N
              len += 4
            else
              raise StandardError.new("unsupported template: '#{byte.chr}' in '#{template}'")
            end
          }
          raise DecodeError.new("limit exceeded") if @limit < @index + len
          arr = @data.unpack("@#{@index}#{template}")
          @index += len
          return arr
        end

def get_string
          raise DecodeError.new("limit exceeded") if @limit <= @index
          len = @data[@index].ord
          raise DecodeError.new("limit exceeded") if @limit < @index + 1 + len
          d = @data[@index + 1, len]
          @index += 1 + len
          return d
        end

def get_string_list
          strings = []
          while @index < @limit
            strings << self.get_string
          end
          strings
        end

def get_name
          return Name.new(self.get_labels)
        end

def get_labels(limit=nil)
          limit = @index if !limit || @index < limit
          d = []
          while true
            raise DecodeError.new("limit exceeded") if @limit <= @index
            case @data[@index].ord
            when 0
              @index += 1
              return d
            when 192..255
              idx = self.get_unpack('n')[0] & 0x3fff
              if limit <= idx
                raise DecodeError.new("non-backward name pointer")
              end
              save_index = @index
              @index = idx
              d += self.get_labels(limit)
              @index = save_index
              return d
            else
              d << self.get_label
            end
          end
          return d
        end

def get_label
          return Label::Str.new(self.get_string)
        end

def get_question
          name = self.get_name
          type, klass = self.get_unpack("nn")
          return name, Resource.get_class(type, klass)
        end

def get_rr
          name = self.get_name
          type, klass, ttl = self.get_unpack('nnN')
          typeclass = Resource.get_class(type, klass)
          res = self.get_length16 { typeclass.decode_rdata self }
          res.instance_variable_set :@ttl, ttl
          return name, ttl, res
        end
      end
    end

##
    # A DNS query abstract class.

class Query
      def encode_rdata(msg) # :nodoc:
        raise EncodeError.new("#{self.class} is query.")
      end

def self.decode_rdata(msg) # :nodoc:
        raise DecodeError.new("#{self.class} is query.")
      end
    end

##
    # A DNS resource abstract class.

class Resource < Query

##
      # Remaining Time To Live for this Resource.

attr_reader :ttl

ClassHash = {} # :nodoc:

def encode_rdata(msg) # :nodoc:
        raise NotImplementedError.new
      end

def self.decode_rdata(msg) # :nodoc:
        raise NotImplementedError.new
      end

def ==(other) # :nodoc:
        return false unless self.class == other.class
        s_ivars = self.instance_variables
        s_ivars.sort!
        s_ivars.delete "@ttl"
        o_ivars = other.instance_variables
        o_ivars.sort!
        o_ivars.delete "@ttl"
        return s_ivars == o_ivars &&
          s_ivars.collect {|name| self.instance_variable_get name} ==
            o_ivars.collect {|name| other.instance_variable_get name}
      end

def eql?(other) # :nodoc:
        return self == other
      end

def hash # :nodoc:
        h = 0
        vars = self.instance_variables
        vars.delete "@ttl"
        vars.each {|name|
          h ^= self.instance_variable_get(name).hash
        }
        return h
      end

def self.get_class(type_value, class_value) # :nodoc:
        return ClassHash[[type_value, class_value]] ||
               Generic.create(type_value, class_value)
      end

##
      # A generic resource abstract class.

class Generic < Resource

##
        # Creates a new generic resource.

def initialize(data)
          @data = data
        end

##
        # Data for this generic resource.

attr_reader :data

def encode_rdata(msg) # :nodoc:
          msg.put_bytes(data)
        end

def self.decode_rdata(msg) # :nodoc:
          return self.new(msg.get_bytes)
        end

def self.create(type_value, class_value) # :nodoc:
          c = Class.new(Generic)
          c.const_set(:TypeValue, type_value)
          c.const_set(:ClassValue, class_value)
          Generic.const_set("Type#{type_value}_Class#{class_value}", c)
          ClassHash[[type_value, class_value]] = c
          return c
        end
      end

##
      # Domain Name resource abstract class.

class DomainName < Resource

##
        # Creates a new DomainName from +name+.

def initialize(name)
          @name = name
        end

##
        # The name of this DomainName.

attr_reader :name

def encode_rdata(msg) # :nodoc:
          msg.put_name(@name)
        end

def self.decode_rdata(msg) # :nodoc:
          return self.new(msg.get_name)
        end
      end

# Standard (class generic) RRs

ClassValue = nil # :nodoc:

##
      # An authoritative name server.

class NS < DomainName
        TypeValue = 2 # :nodoc:
      end

##
      # The canonical name for an alias.

class CNAME < DomainName
        TypeValue = 5 # :nodoc:
      end

##
      # Start Of Authority resource.

class SOA < Resource

TypeValue = 6 # :nodoc:

##
        # Creates a new SOA record.  See the attr documentation for the
        # details of each argument.

def initialize(mname, rname, serial, refresh, retry_, expire, minimum)
          @mname = mname
          @rname = rname
          @serial = serial
          @refresh = refresh
          @retry = retry_
          @expire = expire
          @minimum = minimum
        end

##
        # Name of the host where the master zone file for this zone resides.

attr_reader :mname

##
        # The person responsible for this domain name.

attr_reader :rname

##
        # The version number of the zone file.

attr_reader :serial

##
        # How often, in seconds, a secondary name server is to check for
        # updates from the primary name server.

attr_reader :refresh

##
        # How often, in seconds, a secondary name server is to retry after a
        # failure to check for a refresh.

attr_reader :retry

##
        # Time in seconds that a secondary name server is to use the data
        # before refreshing from the primary name server.

attr_reader :expire

##
        # The minimum number of seconds to be used for TTL values in RRs.

attr_reader :minimum

def encode_rdata(msg) # :nodoc:
          msg.put_name(@mname)
          msg.put_name(@rname)
          msg.put_pack('NNNNN', @serial, @refresh, @retry, @expire, @minimum)
        end

def self.decode_rdata(msg) # :nodoc:
          mname = msg.get_name
          rname = msg.get_name
          serial, refresh, retry_, expire, minimum = msg.get_unpack('NNNNN')
          return self.new(
            mname, rname, serial, refresh, retry_, expire, minimum)
        end
      end

##
      # A Pointer to another DNS name.

class PTR < DomainName
        TypeValue = 12 # :nodoc:
      end

##
      # Host Information resource.

class HINFO < Resource

TypeValue = 13 # :nodoc:

##
        # Creates a new HINFO running +os+ on +cpu+.

def initialize(cpu, os)
          @cpu = cpu
          @os = os
        end

##
        # CPU architecture for this resource.

attr_reader :cpu

##
        # Operating system for this resource.

attr_reader :os

def encode_rdata(msg) # :nodoc:
          msg.put_string(@cpu)
          msg.put_string(@os)
        end

def self.decode_rdata(msg) # :nodoc:
          cpu = msg.get_string
          os = msg.get_string
          return self.new(cpu, os)
        end
      end

##
      # Mailing list or mailbox information.

class MINFO < Resource

TypeValue = 14 # :nodoc:

def initialize(rmailbx, emailbx)
          @rmailbx = rmailbx
          @emailbx = emailbx
        end

##
        # Domain name responsible for this mail list or mailbox.

attr_reader :rmailbx

##
        # Mailbox to use for error messages related to the mail list or mailbox.

attr_reader :emailbx

def encode_rdata(msg) # :nodoc:
          msg.put_name(@rmailbx)
          msg.put_name(@emailbx)
        end

def self.decode_rdata(msg) # :nodoc:
          rmailbx = msg.get_string
          emailbx = msg.get_string
          return self.new(rmailbx, emailbx)
        end
      end

##
      # Mail Exchanger resource.

class MX < Resource

TypeValue= 15 # :nodoc:

##
        # Creates a new MX record with +preference+, accepting mail at
        # +exchange+.

def initialize(preference, exchange)
          @preference = preference
          @exchange = exchange
        end

##
        # The preference for this MX.

attr_reader :preference

##
        # The host of this MX.

attr_reader :exchange

def encode_rdata(msg) # :nodoc:
          msg.put_pack('n', @preference)
          msg.put_name(@exchange)
        end

def self.decode_rdata(msg) # :nodoc:
          preference, = msg.get_unpack('n')
          exchange = msg.get_name
          return self.new(preference, exchange)
        end
      end

##
      # Unstructured text resource.

class TXT < Resource

TypeValue = 16 # :nodoc:

def initialize(first_string, *rest_strings)
          @strings = [first_string, *rest_strings]
        end

##
        # Returns an Array of Strings for this TXT record.

attr_reader :strings

##
        # Returns the concatenated string from +strings+.

def data
          @strings.join("")
        end

def encode_rdata(msg) # :nodoc:
          msg.put_string_list(@strings)
        end

def self.decode_rdata(msg) # :nodoc:
          strings = msg.get_string_list
          return self.new(*strings)
        end
      end

##
      # A Query type requesting any RR.

class ANY < Query
        TypeValue = 255 # :nodoc:
      end

ClassInsensitiveTypes = [ # :nodoc:
        NS, CNAME, SOA, PTR, HINFO, MINFO, MX, TXT, ANY
      ]

##
      # module IN contains ARPA Internet specific RRs.

module IN

ClassValue = 1 # :nodoc:

ClassInsensitiveTypes.each {|s|
          c = Class.new(s)
          c.const_set(:TypeValue, s::TypeValue)
          c.const_set(:ClassValue, ClassValue)
          ClassHash[[s::TypeValue, ClassValue]] = c
          self.const_set(s.name.sub(/.*::/, ''), c)
        }

##
        # IPv4 Address resource

class A < Resource
          TypeValue = 1
          ClassValue = IN::ClassValue
          ClassHash[[TypeValue, ClassValue]] = self # :nodoc:

##
          # Creates a new A for +address+.

def initialize(address)
            @address = IPv4.create(address)
          end

##
          # The Resolv::IPv4 address for this A.

attr_reader :address

def encode_rdata(msg) # :nodoc:
            msg.put_bytes(@address.address)
          end

def self.decode_rdata(msg) # :nodoc:
            return self.new(IPv4.new(msg.get_bytes(4)))
          end
        end

##
        # Well Known Service resource.

class WKS < Resource
          TypeValue = 11
          ClassValue = IN::ClassValue
          ClassHash[[TypeValue, ClassValue]] = self # :nodoc:

def initialize(address, protocol, bitmap)
            @address = IPv4.create(address)
            @protocol = protocol
            @bitmap = bitmap
          end

##
          # The host these services run on.

attr_reader :address

##
          # IP protocol number for these services.

attr_reader :protocol

##
          # A bit map of enabled services on this host.
          #
          # If protocol is 6 (TCP) then the 26th bit corresponds to the SMTP
          # service (port 25).  If this bit is set, then an SMTP server should
          # be listening on TCP port 25; if zero, SMTP service is not
          # supported.

attr_reader :bitmap

def encode_rdata(msg) # :nodoc:
            msg.put_bytes(@address.address)
            msg.put_pack("n", @protocol)
            msg.put_bytes(@bitmap)
          end

def self.decode_rdata(msg) # :nodoc:
            address = IPv4.new(msg.get_bytes(4))
            protocol, = msg.get_unpack("n")
            bitmap = msg.get_bytes
            return self.new(address, protocol, bitmap)
          end
        end

##
        # An IPv6 address record.

class AAAA < Resource
          TypeValue = 28
          ClassValue = IN::ClassValue
          ClassHash[[TypeValue, ClassValue]] = self # :nodoc:

##
          # Creates a new AAAA for +address+.

def initialize(address)
            @address = IPv6.create(address)
          end

##
          # The Resolv::IPv6 address for this AAAA.

attr_reader :address

def encode_rdata(msg) # :nodoc:
            msg.put_bytes(@address.address)
          end

def self.decode_rdata(msg) # :nodoc:
            return self.new(IPv6.new(msg.get_bytes(16)))
          end
        end

##
        # SRV resource record defined in RFC 2782
        #
        # These records identify the hostname and port that a service is
        # available at.

class SRV < Resource
          TypeValue = 33
          ClassValue = IN::ClassValue
          ClassHash[[TypeValue, ClassValue]] = self # :nodoc:

# Create a SRV resource record.
          #
          # See the documentation for #priority, #weight, #port and #target
          # for +priority+, +weight+, +port and +target+ respectively.

def initialize(priority, weight, port, target)
            @priority = priority.to_int
            @weight = weight.to_int
            @port = port.to_int
            @target = Name.create(target)
          end

# The priority of this target host.
          #
          # A client MUST attempt to contact the target host with the
          # lowest-numbered priority it can reach; target hosts with the same
          # priority SHOULD be tried in an order defined by the weight field.
          # The range is 0-65535.  Note that it is not widely implemented and
          # should be set to zero.

attr_reader :priority

# A server selection mechanism.
          #
          # The weight field specifies a relative weight for entries with the
          # same priority. Larger weights SHOULD be given a proportionately
          # higher probability of being selected. The range of this number is
          # 0-65535.  Domain administrators SHOULD use Weight 0 when there
          # isn't any server selection to do, to make the RR easier to read
          # for humans (less noisy). Note that it is not widely implemented
          # and should be set to zero.

attr_reader :weight

# The port on this target host of this service.
          #
          # The range is 0-65535.

attr_reader :port

# The domain name of the target host.
          #
          # A target of "." means that the service is decidedly not available
          # at this domain.

attr_reader :target

def encode_rdata(msg) # :nodoc:
            msg.put_pack("n", @priority)
            msg.put_pack("n", @weight)
            msg.put_pack("n", @port)
            msg.put_name(@target)
          end

def self.decode_rdata(msg) # :nodoc:
            priority, = msg.get_unpack("n")
            weight,   = msg.get_unpack("n")
            port,     = msg.get_unpack("n")
            target    = msg.get_name
            return self.new(priority, weight, port, target)
          end
        end
      end
    end
  end

##
  # A Resolv::DNS IPv4 address.

class IPv4

##
    # Regular expression IPv4 addresses must match.

Regex256 = /0
               |1(?:[0-9][0-9]?)?
               |2(?:[0-4][0-9]?|5[0-5]?|[6-9])?
               |[3-9][0-9]?/x
    Regex = /\A(#{Regex256})\.(#{Regex256})\.(#{Regex256})\.(#{Regex256})\z/

def self.create(arg)
      case arg
      when IPv4
        return arg
      when Regex
        if (0..255) === (a = $1.to_i) &&
           (0..255) === (b = $2.to_i) &&
           (0..255) === (c = $3.to_i) &&
           (0..255) === (d = $4.to_i)
          return self.new([a, b, c, d].pack("CCCC"))
        else
          raise ArgumentError.new("IPv4 address with invalid value: " + arg)
        end
      else
        raise ArgumentError.new("cannot interpret as IPv4 address: #{arg.inspect}")
      end
    end

def initialize(address) # :nodoc:
      unless address.kind_of?(String)
        raise ArgumentError, 'IPv4 address must be a string'
      end
      unless address.length == 4
        raise ArgumentError, "IPv4 address expects 4 bytes but #{address.length} bytes"
      end
      @address = address
    end

##
    # A String representation of this IPv4 address.

##
    # The raw IPv4 address as a String.

attr_reader :address

def to_s # :nodoc:
      return sprintf("%d.%d.%d.%d", *@address.unpack("CCCC"))
    end

def inspect # :nodoc:
      return "#<#{self.class} #{self.to_s}>"
    end

##
    # Turns this IPv4 address into a Resolv::DNS::Name.

def to_name
      return DNS::Name.create(
        '%d.%d.%d.%d.in-addr.arpa.' % @address.unpack('CCCC').reverse)
    end

def ==(other) # :nodoc:
      return @address == other.address
    end

def eql?(other) # :nodoc:
      return self == other
    end

def hash # :nodoc:
      return @address.hash
    end
  end

##
  # A Resolv::DNS IPv6 address.

class IPv6

##
    # IPv6 address format a:b:c:d:e:f:g:h
    Regex_8Hex = /\A
      (?:[0-9A-Fa-f]{1,4}:){7}
         [0-9A-Fa-f]{1,4}
      \z/x

##
    # Compressed IPv6 address format a::b

Regex_CompressedHex = /\A
      ((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?) ::
      ((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)
      \z/x

##
    # IPv4 mapped IPv6 address format a:b:c:d:e:f:w.x.y.z

Regex_6Hex4Dec = /\A
      ((?:[0-9A-Fa-f]{1,4}:){6,6})
      (\d+)\.(\d+)\.(\d+)\.(\d+)
      \z/x

##
    # Compressed IPv4 mapped IPv6 address format a::b:w.x.y.z

Regex_CompressedHex4Dec = /\A
      ((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?) ::
      ((?:[0-9A-Fa-f]{1,4}:)*)
      (\d+)\.(\d+)\.(\d+)\.(\d+)
      \z/x

##
    # A composite IPv6 address Regexp.

Regex = /
      (?:#{Regex_8Hex}) |
      (?:#{Regex_CompressedHex}) |
      (?:#{Regex_6Hex4Dec}) |
      (?:#{Regex_CompressedHex4Dec})/x

##
    # Creates a new IPv6 address from +arg+ which may be:
    #
    # IPv6:: returns +arg+.
    # String:: +arg+ must match one of the IPv6::Regex* constants

def self.create(arg)
      case arg
      when IPv6
        return arg
      when String
        address = ''
        if Regex_8Hex =~ arg
          arg.scan(/[0-9A-Fa-f]+/) {|hex| address << [hex.hex].pack('n')}
        elsif Regex_CompressedHex =~ arg
          prefix = $1
          suffix = $2
          a1 = ''
          a2 = ''
          prefix.scan(/[0-9A-Fa-f]+/) {|hex| a1 << [hex.hex].pack('n')}
          suffix.scan(/[0-9A-Fa-f]+/) {|hex| a2 << [hex.hex].pack('n')}
          omitlen = 16 - a1.length - a2.length
          address << a1 << "\0" * omitlen << a2
        elsif Regex_6Hex4Dec =~ arg
          prefix, a, b, c, d = $1, $2.to_i, $3.to_i, $4.to_i, $5.to_i
          if (0..255) === a && (0..255) === b && (0..255) === c && (0..255) === d
            prefix.scan(/[0-9A-Fa-f]+/) {|hex| address << [hex.hex].pack('n')}
            address << [a, b, c, d].pack('CCCC')
          else
            raise ArgumentError.new("not numeric IPv6 address: " + arg)
          end
        elsif Regex_CompressedHex4Dec =~ arg
          prefix, suffix, a, b, c, d = $1, $2, $3.to_i, $4.to_i, $5.to_i, $6.to_i
          if (0..255) === a && (0..255) === b && (0..255) === c && (0..255) === d
            a1 = ''
            a2 = ''
            prefix.scan(/[0-9A-Fa-f]+/) {|hex| a1 << [hex.hex].pack('n')}
            suffix.scan(/[0-9A-Fa-f]+/) {|hex| a2 << [hex.hex].pack('n')}
            omitlen = 12 - a1.length - a2.length
            address << a1 << "\0" * omitlen << a2 << [a, b, c, d].pack('CCCC')
          else
            raise ArgumentError.new("not numeric IPv6 address: " + arg)
          end
        else
          raise ArgumentError.new("not numeric IPv6 address: " + arg)
        end
        return IPv6.new(address)
      else
        raise ArgumentError.new("cannot interpret as IPv6 address: #{arg.inspect}")
      end
    end

def initialize(address) # :nodoc:
      unless address.kind_of?(String) && address.length == 16
        raise ArgumentError.new('IPv6 address must be 16 bytes')
      end
      @address = address
    end

##
    # The raw IPv6 address as a String.

attr_reader :address

def to_s # :nodoc:
      address = sprintf("%X:%X:%X:%X:%X:%X:%X:%X", *@address.unpack("nnnnnnnn"))
      unless address.sub!(/(^|:)0(:0)+(:|$)/, '::')
        address.sub!(/(^|:)0(:|$)/, '::')
      end
      return address
    end

def inspect # :nodoc:
      return "#<#{self.class} #{self.to_s}>"
    end

##
    # Turns this IPv6 address into a Resolv::DNS::Name.
    #--
    # ip6.arpa should be searched too. [RFC3152]

def to_name
      return DNS::Name.new(
        @address.unpack("H32")[0].split(//).reverse + ['ip6', 'arpa'])
    end

def ==(other) # :nodoc:
      return @address == other.address
    end

def eql?(other) # :nodoc:
      return self == other
    end

def hash # :nodoc:
      return @address.hash
    end
  end

##
  # Default resolver to use for Resolv class methods.

DefaultResolver = self.new

##
  # Address Regexp to use for matching IP addresses.

AddressRegex = /(?:#{IPv4::Regex})|(?:#{IPv6::Regex})/

end

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