=begin = resolv library resolv.rb is a resolver library written in Ruby. Since it is written in Ruby, it is thread-aware. I.e. it can resolv many hostnames concurrently. It is possible to lookup various resources of DNS using DNS module directly. == example p Resolv.getaddress("www.ruby-lang.org") p Resolv.getname("210.251.121.214") Resolv::DNS.open {|dns| p dns.getresources("www.ruby-lang.org", Resolv::DNS::Resource::IN::A).collect {|r| r.address} p dns.getresources("ruby-lang.org", Resolv::DNS::Resource::IN::MX).collect {|r| [r.exchange.to_s, r.preference]} } == Resolv class === class methods --- Resolv.getaddress(name) --- Resolv.getaddresses(name) --- Resolv.each_address(name) {|address| ...} They lookups IP addresses of ((|name|)) which represents a hostname as a string by default resolver. getaddress returns first entry of lookupped addresses. getaddresses returns lookupped addresses as an array. each_address iterates over lookupped addresses. --- Resolv.getname(address) --- Resolv.getnames(address) --- Resolv.each_name(address) {|name| ...} lookups hostnames of ((|address|)) which represents IP address as a string. getname returns first entry of lookupped names. getnames returns lookupped names as an array. each_names iterates over lookupped names. == Resolv::Hosts class hostname resolver using /etc/hosts format. === class methods --- Resolv::Hosts.new(hosts='/etc/hosts') === methods --- Resolv::Hosts#getaddress(name) --- Resolv::Hosts#getaddresses(name) --- Resolv::Hosts#each_address(name) {|address| ...} address lookup methods. --- Resolv::Hosts#getname(address) --- Resolv::Hosts#getnames(address) --- Resolv::Hosts#each_name(address) {|name| ...} hostnames lookup methods. == Resolv::DNS class DNS stub resolver. === class methods --- Resolv::DNS.new(config_info=nil) ((|config_info|)) should be nil, a string or a hash. If nil is given, /etc/resolv.conf and platform specific information is used. If a string is given, it should be a filename which format is same as /etc/resolv.conf. If a hash is given, it may contains information for nameserver, search and ndots as follows. Resolv::DNS.new({:nameserver=>["210.251.121.21"], :search=>["ruby-lang.org"], :ndots=>1}) --- Resolv::DNS.open(config_info=nil) --- Resolv::DNS.open(config_info=nil) {|dns| ...} === methods --- Resolv::DNS#close --- Resolv::DNS#getaddress(name) --- Resolv::DNS#getaddresses(name) --- Resolv::DNS#each_address(name) {|address| ...} address lookup methods. ((|name|)) must be a instance of Resolv::DNS::Name or String. Lookupped address is represented as an instance of Resolv::IPv4 or Resolv::IPv6. --- Resolv::DNS#getname(address) --- Resolv::DNS#getnames(address) --- Resolv::DNS#each_name(address) {|name| ...} hostnames lookup methods. ((|address|)) must be a instance of Resolv::IPv4, Resolv::IPv6 or String. Lookupped name is represented as an instance of Resolv::DNS::Name. --- Resolv::DNS#getresource(name, typeclass) --- Resolv::DNS#getresources(name, typeclass) --- Resolv::DNS#each_resource(name, typeclass) {|resource| ...} They lookup DNS resources of ((|name|)). ((|name|)) must be a instance of Resolv::Name or String. ((|typeclass|)) should be one of follows: * Resolv::DNS::Resource::IN::ANY * Resolv::DNS::Resource::IN::NS * Resolv::DNS::Resource::IN::CNAME * Resolv::DNS::Resource::IN::SOA * Resolv::DNS::Resource::IN::HINFO * Resolv::DNS::Resource::IN::MINFO * Resolv::DNS::Resource::IN::MX * Resolv::DNS::Resource::IN::TXT * Resolv::DNS::Resource::IN::ANY * Resolv::DNS::Resource::IN::A * Resolv::DNS::Resource::IN::WKS * Resolv::DNS::Resource::IN::PTR * Resolv::DNS::Resource::IN::AAAA Lookupped resource is represented as an instance of (a subclass of) Resolv::DNS::Resource. (Resolv::DNS::Resource::IN::A, etc.) == Resolv::DNS::Resource::IN::NS class --- name == Resolv::DNS::Resource::IN::CNAME class --- name == Resolv::DNS::Resource::IN::SOA class --- mname --- rname --- serial --- refresh --- retry --- expire --- minimum == Resolv::DNS::Resource::IN::HINFO class --- cpu --- os == Resolv::DNS::Resource::IN::MINFO class --- rmailbx --- emailbx == Resolv::DNS::Resource::IN::MX class --- preference --- exchange == Resolv::DNS::Resource::IN::TXT class --- data == Resolv::DNS::Resource::IN::A class --- address == Resolv::DNS::Resource::IN::WKS class --- address --- protocol --- bitmap == Resolv::DNS::Resource::IN::PTR class --- name == Resolv::DNS::Resource::IN::AAAA class --- address == Resolv::DNS::Name class === class methods --- Resolv::DNS::Name.create(name) === methods --- Resolv::DNS::Name#to_s == Resolv::DNS::Resource class == Resolv::IPv4 class === class methods --- Resolv::IPv4.create(address) === methods --- Resolv::IPv4#to_s --- Resolv::IPv4#to_name === constants --- Resolv::IPv4::Regex regular expression for IPv4 address. == Resolv::IPv6 class === class methods --- Resolv::IPv6.create(address) === methods --- Resolv::IPv6#to_s --- Resolv::IPv6#to_name === constants --- Resolv::IPv6::Regex regular expression for IPv6 address. == Bugs * NIS is not supported. * /etc/nsswitch.conf is not supported. * IPv6 is not supported. =end require 'socket' require 'fcntl' require 'timeout' require 'thread' class Resolv def self.getaddress(name) DefaultResolver.getaddress(name) end def self.getaddresses(name) DefaultResolver.getaddresses(name) end def self.each_address(name, &block) DefaultResolver.each_address(name, &block) end def self.getname(address) DefaultResolver.getname(address) end def self.getnames(address) DefaultResolver.getnames(address) end def self.each_name(address, &proc) DefaultResolver.each_name(address, &proc) end def initialize(resolvers=[Hosts.new, DNS.new]) @resolvers = resolvers end def getaddress(name) each_address(name) {|address| return address} raise ResolvError.new("no address for #{name}") end def getaddresses(name) ret = [] each_address(name) {|address| ret << address} return ret end 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 def getname(address) each_name(address) {|name| return name} raise ResolvError.new("no name for #{address}") end def getnames(address) ret = [] each_name(address) {|name| ret << name} return ret end def each_name(address) yielded = false @resolvers.each {|r| r.each_name(address) {|name| yield name.to_s yielded = true } return if yielded } end class ResolvError < StandardError end class ResolvTimeout < TimeoutError end class Hosts if /mswin32|cygwin|mingw|bccwin/ =~ RUBY_PLATFORM require 'win32/resolv' DefaultFileName = Win32::Resolv.get_hosts_path else DefaultFileName = '/etc/hosts' end def initialize(filename = DefaultFileName) @filename = filename @mutex = Mutex.new @initialized = nil end def lazy_initialize @mutex.synchronize { unless @initialized @name2addr = {} @addr2name = {} open(@filename) {|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 def getaddress(name) each_address(name) {|address| return address} raise ResolvError.new("#{@filename} has no name: #{name}") end def getaddresses(name) ret = [] each_address(name) {|address| ret << address} return ret end def each_address(name, &proc) lazy_initialize if @name2addr.include?(name) @name2addr[name].each(&proc) end end def getname(address) each_name(address) {|name| return name} raise ResolvError.new("#{@filename} has no address: #{address}") end def getnames(address) ret = [] each_name(address) {|name| ret << name} return ret end def each_name(address, &proc) lazy_initialize if @addr2name.include?(address) @addr2name[address].each(&proc) end end end class DNS # STD0013 (RFC 1035, etc.) # ftp://ftp.isi.edu/in-notes/iana/assignments/dns-parameters Port = 53 UDPSize = 512 DNSThreadGroup = ThreadGroup.new def self.open(*args) dns = new(*args) return dns unless block_given? begin yield dns ensure dns.close end end def initialize(config_info=nil) @mutex = Mutex.new @config = Config.new(config_info) @initialized = nil end def lazy_initialize @mutex.synchronize { unless @initialized @config.lazy_initialize if nameserver = @config.single? @requester = Requester::ConnectedUDP.new(nameserver) else @requester = Requester::UnconnectedUDP.new end @initialized = true end } self end def close @mutex.synchronize { if @initialized @requester.close if @requester @requester = nil @initialized = false end } end def getaddress(name) each_address(name) {|address| return address} raise ResolvError.new("DNS result has no information for #{name}") end def getaddresses(name) ret = [] each_address(name) {|address| ret << address} return ret end def each_address(name) each_resource(name, Resource::IN::A) {|resource| yield resource.address} end def getname(address) each_name(address) {|name| return name} raise ResolvError.new("DNS result has no information for #{address}") end def getnames(address) ret = [] each_name(address) {|name| ret << name} return ret end 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 def getresource(name, typeclass) each_resource(name, typeclass) {|resource| return resource} raise ResolvError.new("DNS result has no information for #{name}") end def getresources(name, typeclass) ret = [] each_resource(name, typeclass) {|resource| ret << resource} return ret end def each_resource(name, typeclass, &proc) lazy_initialize q = Queue.new senders = {} begin @config.resolv(name) {|candidate, tout, nameserver| msg = Message.new msg.rd = 1 msg.add_question(candidate, typeclass) unless sender = senders[[candidate, nameserver]] sender = senders[[candidate, nameserver]] = @requester.sender(msg, candidate, q, nameserver) end sender.send reply = reply_name = nil timeout(tout, ResolvTimeout) { reply, reply_name = q.pop } case reply.rcode when RCode::NoError extract_resources(reply, reply_name, typeclass, &proc) return when RCode::NXDomain raise Config::NXDomain.new(reply_name.to_s) else raise Config::OtherResolvError.new(reply_name.to_s) end } ensure @requester.delete(q) end end def extract_resources(msg, name, typeclass) 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 class Requester def initialize @senders = {} end def close thread, sock, @thread, @sock = @thread, @sock begin if thread thread.kill thread.join end ensure sock.close if sock end end def delete(arg) case arg when Sender @senders.delete_if {|k, s| s == arg } when Queue @senders.delete_if {|k, s| s.queue == arg } else raise ArgumentError.new("neither Sender or Queue: #{arg}") end end class Sender def initialize(msg, data, sock, queue) @msg = msg @data = data @sock = sock @queue = queue end attr_reader :queue def recv(msg) @queue.push([msg, @data]) end end class UnconnectedUDP < Requester def initialize super() @sock = UDPSocket.new @sock.fcntl(Fcntl::F_SETFD, 1) if defined? Fcntl::F_SETFD @id = {} @id.default = -1 @thread = Thread.new { DNSThreadGroup.add Thread.current loop { reply, from = @sock.recvfrom(UDPSize) msg = begin Message.decode(reply) rescue DecodeError STDERR.print("DNS message decoding error: #{reply.inspect}\n") next end if s = @senders[[[from[3],from[1]],msg.id]] s.recv msg else #STDERR.print("non-handled DNS message: #{msg.inspect} from #{from.inspect}\n") end } } end def sender(msg, data, queue, host, port=Port) service = [host, port] id = Thread.exclusive { @id[service] = (@id[service] + 1) & 0xffff } request = msg.encode request[0,2] = [id].pack('n') return @senders[[service, id]] = Sender.new(request, data, @sock, host, port, queue) end class Sender < Requester::Sender def initialize(msg, data, sock, host, port, queue) super(msg, data, sock, queue) @host = host @port = port end def send @sock.send(@msg, 0, @host, @port) end end end class ConnectedUDP < Requester def initialize(host, port=Port) super() @host = host @port = port @sock = UDPSocket.new @sock.connect(host, port) @sock.fcntl(Fcntl::F_SETFD, 1) if defined? Fcntl::F_SETFD @id = -1 @thread = Thread.new { DNSThreadGroup.add Thread.current loop { reply = @sock.recv(UDPSize) msg = begin Message.decode(reply) rescue DecodeError STDERR.print("DNS message decoding error: #{reply.inspect}") next end if s = @senders[msg.id] s.recv msg else #STDERR.print("non-handled DNS message: #{msg.inspect}") end } } end def sender(msg, data, queue, host=@host, port=@port) unless host == @host && port == @port raise RequestError.new("host/port don't match: #{host}:#{port}") end id = Thread.exclusive { @id = (@id + 1) & 0xffff } request = msg.encode request[0,2] = [id].pack('n') return @senders[id] = Sender.new(request, data, @sock, queue) end class Sender < Requester::Sender def send @sock.send(@msg, 0) end end end class TCP < Requester def initialize(host, port=Port) super() @host = host @port = port @sock = TCPSocket.new @sock.connect(host, port) @sock.fcntl(Fcntl::F_SETFD, 1) if defined? Fcntl::F_SETFD @id = -1 @senders = {} @thread = Thread.new { DNSThreadGroup.add Thread.current loop { len = @sock.read(2).unpack('n') reply = @sock.read(len) msg = begin Message.decode(reply) rescue DecodeError STDERR.print("DNS message decoding error: #{reply.inspect}") next end if s = @senders[msg.id] s.push msg else #STDERR.print("non-handled DNS message: #{msg.inspect}") end } } end def sender(msg, data, queue, host=@host, port=@port) unless host == @host && port == @port raise RequestError.new("host/port don't match: #{host}:#{port}") end id = Thread.exclusive { @id = (@id + 1) & 0xffff } request = msg.encode request[0,2] = [request.length, id].pack('nn') return @senders[id] = Sender.new(request, data, @sock, queue) end class Sender < Requester::Sender def send @sock.print(@msg) @sock.flush end end end class RequestError < StandardError end end class Config 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) {|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 = $1.to_i end } end } } return { :nameserver => nameserver, :search => search, :ndots => ndots } end def Config.default_config_hash(filename="/etc/resolv.conf") if File.exist? filename config_hash = Config.parse_resolv_conf(filename) else if /mswin32|cygwin|mingw|bccwin/ =~ RUBY_PLATFORM search, nameserver = Win32::Resolv.get_resolv_info config_hash = {} config_hash[:nameserver] = nameserver if nameserver config_hash[:search] = [search].flatten if search end end config_hash end def lazy_initialize @mutex.synchronize { unless @initialized @nameserver = [] @search = nil @ndots = 1 case @config_info when nil config_hash = Config.default_config_hash when String config_hash = Config.parse_resolv_conf(@config_info) when Hash config_hash = @config_info.dup if String === config_hash[:nameserver] config_hash[:nameserver] = [config_hash[:nameserver]] end if String === config_hash[:search] config_hash[:search] = [config_hash[:search]] end else raise ArgumentError.new("invalid resolv configuration: #{@config_info.inspect}") end @nameserver = config_hash[:nameserver] if config_hash.include? :nameserver @search = config_hash[:search] if config_hash.include? :search @ndots = config_hash[:ndots] if config_hash.include? :ndots @nameserver = ['0.0.0.0'] if @nameserver.empty? if @search @search = @search.map {|arg| Label.split(arg) } else hostname = Socket.gethostname if /\./ =~ hostname @search = [Label.split($')] else @search = [[]] end end if !@nameserver.kind_of?(Array) || !@nameserver.all? {|ns| String === ns } raise ArgumentError.new("invalid nameserver config: #{@nameserver.inspect}") end if !@search.kind_of?(Array) || !@search.all? {|ls| ls.all? {|l| Label::Str === l } } raise ArgumentError.new("invalid search config: #{@search.inspect}") end if !@ndots.kind_of?(Integer) raise ArgumentError.new("invalid ndots config: #{@ndots.inspect}") end @initialized = true end } self end def single? lazy_initialize if @nameserver.length == 1 return @nameserver[0] else return nil end 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.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.each {|nameserver| begin yield candidate, tout, nameserver rescue ResolvTimeout end } } raise ResolvError.new("DNS resolv timeout: #{name}") rescue NXDomain end } rescue ResolvError end end class NXDomain < ResolvError end class OtherResolvError < ResolvError end end module OpCode Query = 0 IQuery = 1 Status = 2 Notify = 4 Update = 5 end module RCode 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 class DecodeError < StandardError end class EncodeError < StandardError end module Label def self.split(arg) labels = [] arg.scan(/[^\.]+/) {labels << Str.new($&)} return labels end class Str 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 class 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) @labels = labels @absolute = absolute end def inspect "#<#{self.class}: #{self.to_s}#{@absolute ? '.' : ''}>" end def absolute? return @absolute end def ==(other) return false unless Name === other return @labels == other.to_a && @absolute == other.absolute? end alias eql? == # tests subdomain-of relation. # # 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 return @labels.hash ^ @absolute.hash end def to_a return @labels end def length return @labels.length end def [](i) 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. # # 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 @@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 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.string) 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 def initialize(data) @data = data @index = 0 @limit = data.length yield self 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) d = @data[@index, len] @index += len return d end def get_unpack(template) len = 0 template.each_byte {|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 len = @data[@index] 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 case @data[@index] 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) return name, ttl, self.get_length16 {typeclass.decode_rdata(self)} end end end class Query def encode_rdata(msg) raise EncodeError.new("#{self.class} is query.") end def self.decode_rdata(msg) raise DecodeError.new("#{self.class} is query.") end end class Resource < Query ClassHash = {} def encode_rdata(msg) raise NotImplementedError.new end def self.decode_rdata(msg) raise NotImplementedError.new end def ==(other) return self.class == other.class && self.instance_variables == other.instance_variables && self.instance_variables.collect {|name| self.instance_eval name} == other.instance_variables.collect {|name| other.instance_eval name} end def eql?(other) return self == other end def hash h = 0 self.instance_variables.each {|name| h ^= self.instance_eval("#{name}.hash") } return h end def self.get_class(type_value, class_value) return ClassHash[[type_value, class_value]] || Generic.create(type_value, class_value) end class Generic < Resource def initialize(data) @data = data end attr_reader :data def encode_rdata(msg) msg.put_bytes(data) end def self.decode_rdata(msg) return self.new(msg.get_bytes) end def self.create(type_value, class_value) 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 class DomainName < Resource def initialize(name) @name = name end attr_reader :name def encode_rdata(msg) msg.put_name(@name) end def self.decode_rdata(msg) return self.new(msg.get_name) end end # Standard (class generic) RRs ClassValue = nil class NS < DomainName TypeValue = 2 end class CNAME < DomainName TypeValue = 5 end class SOA < Resource TypeValue = 6 def initialize(mname, rname, serial, refresh, retry_, expire, minimum) @mname = mname @rname = rname @serial = serial @refresh = refresh @retry = retry_ @expire = expire @minimum = minimum end attr_reader :mname, :rname, :serial, :refresh, :retry, :expire, :minimum def encode_rdata(msg) msg.put_name(@mname) msg.put_name(@rname) msg.put_pack('NNNNN', @serial, @refresh, @retry, @expire, @minimum) end def self.decode_rdata(msg) 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 class PTR < DomainName TypeValue = 12 end class HINFO < Resource TypeValue = 13 def initialize(cpu, os) @cpu = cpu @os = os end attr_reader :cpu, :os def encode_rdata(msg) msg.put_string(@cpu) msg.put_string(@os) end def self.decode_rdata(msg) cpu = msg.get_string os = msg.get_string return self.new(cpu, os) end end class MINFO < Resource TypeValue = 14 def initialize(rmailbx, emailbx) @rmailbx = rmailbx @emailbx = emailbx end attr_reader :rmailbx, :emailbx def encode_rdata(msg) msg.put_name(@rmailbx) msg.put_name(@emailbx) end def self.decode_rdata(msg) rmailbx = msg.get_string emailbx = msg.get_string return self.new(rmailbx, emailbx) end end class MX < Resource TypeValue= 15 def initialize(preference, exchange) @preference = preference @exchange = exchange end attr_reader :preference, :exchange def encode_rdata(msg) msg.put_pack('n', @preference) msg.put_name(@exchange) end def self.decode_rdata(msg) preference, = msg.get_unpack('n') exchange = msg.get_name return self.new(preference, exchange) end end class TXT < Resource TypeValue = 16 def initialize(first_string, *rest_strings) @strings = [first_string, *rest_strings] end attr_reader :strings def data @strings[0] end def encode_rdata(msg) msg.put_string_list(@strings) end def self.decode_rdata(msg) strings = msg.get_string_list return self.new(*strings) end end class ANY < Query TypeValue = 255 end ClassInsensitiveTypes = [ NS, CNAME, SOA, PTR, HINFO, MINFO, MX, TXT, ANY ] # ARPA Internet specific RRs module IN ClassValue = 1 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) } class A < Resource ClassHash[[TypeValue = 1, ClassValue = ClassValue]] = self def initialize(address) @address = IPv4.create(address) end attr_reader :address def encode_rdata(msg) msg.put_bytes(@address.address) end def self.decode_rdata(msg) return self.new(IPv4.new(msg.get_bytes(4))) end end class WKS < Resource ClassHash[[TypeValue = 11, ClassValue = ClassValue]] = self def initialize(address, protocol, bitmap) @address = IPv4.create(address) @protocol = protocol @bitmap = bitmap end attr_reader :address, :protocol, :bitmap def encode_rdata(msg) msg.put_bytes(@address.address) msg.put_pack("n", @protocol) msg.put_bytes(@bitmap) end def self.decode_rdata(msg) address = IPv4.new(msg.get_bytes(4)) protocol, = msg.get_unpack("n") bitmap = msg.get_bytes return self.new(address, protocol, bitmap) end end class AAAA < Resource ClassHash[[TypeValue = 28, ClassValue = ClassValue]] = self def initialize(address) @address = IPv6.create(address) end attr_reader :address def encode_rdata(msg) msg.put_bytes(@address.address) end def self.decode_rdata(msg) 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. # # The format is: # _Service._Proto.Name TTL Class SRV Priority Weight Port Target # # The fields specific to SRV are defined in RFC 2782 as meaning: # - +priority+ 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. # # - +weight+ 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. # # - +port+ The port on this target host of this service. The range is 0- # 65535. # # - +target+ The domain name of the target host. A target of "." means # that the service is decidedly not available at this domain. class SRV < Resource ClassHash[[TypeValue = 33, ClassValue = ClassValue]] = self # Create a SRV resource record. def initialize(priority, weight, port, target) @priority = priority.to_int @weight = weight.to_int @port = port.to_int @target = Name.create(target) end attr_reader :priority, :weight, :port, :target def encode_rdata(msg) 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) 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 class IPv4 Regex = /\A(\d+)\.(\d+)\.(\d+)\.(\d+)\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) unless address.kind_of?(String) && address.length == 4 raise ArgumentError.new('IPv4 address must be 4 bytes') end @address = address end attr_reader :address def to_s return sprintf("%d.%d.%d.%d", *@address.unpack("CCCC")) end def inspect return "#<#{self.class} #{self.to_s}>" end def to_name return DNS::Name.create( '%d.%d.%d.%d.in-addr.arpa.' % @address.unpack('CCCC').reverse) end def ==(other) return @address == other.address end def eql?(other) return self == other end def hash return @address.hash end end class IPv6 Regex_8Hex = /\A (?:[0-9A-Fa-f]{1,4}:){7} [0-9A-Fa-f]{1,4} \z/x 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 Regex_6Hex4Dec = /\A ((?:[0-9A-Fa-f]{1,4}:){6,6}) (\d+)\.(\d+)\.(\d+)\.(\d+) \z/x 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 Regex = / (?:#{Regex_8Hex}) | (?:#{Regex_CompressedHex}) | (?:#{Regex_6Hex4Dec}) | (?:#{Regex_CompressedHex4Dec})/x 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, $6.to_i if (0..255) === a && (0..255) === b && (0..255) === c && (0..255) === d a1 = '' a2 = '' prefix.scan(/[0-9A-Fa-f]+/) {|hex| a1 << [hex.hex].pack('n')} suffix.scan(/[0-9A-Fa-f]+/) {|hex| a2 << [hex.hex].pack('n')} omitlen = 12 - a1.length - a2.length address << a1 << "\0" * omitlen << a2 << [a, b, c, d].pack('CCCC') else raise ArgumentError.new("not numeric IPv6 address: " + arg) end else raise ArgumentError.new("not numeric IPv6 address: " + arg) end return IPv6.new(address) else raise ArgumentError.new("cannot interpret as IPv6 address: #{arg.inspect}") end end def initialize(address) unless address.kind_of?(String) && address.length == 16 raise ArgumentError.new('IPv6 address must be 16 bytes') end @address = address end attr_reader :address def to_s address = sprintf("%X:%X:%X:%X:%X:%X:%X:%X", *@address.unpack("nnnnnnnn")) unless address.sub!(/(^|:)0(:0)+(:|$)/, '::') address.sub!(/(^|:)0(:|$)/, '::') end return address end def inspect return "#<#{self.class} #{self.to_s}>" end def to_name # ip6.arpa should be searched too. [RFC3152] return DNS::Name.new( @address.unpack("H32")[0].split(//).reverse + ['ip6', 'int']) end def ==(other) return @address == other.address end def eql?(other) return self == other end def hash return @address.hash end end DefaultResolver = self.new AddressRegex = /(?:#{IPv4::Regex})|(?:#{IPv6::Regex})/ end