=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(host.index(':') ? Socket::AF_INET6 : Socket::AF_INET)
@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