Class: Resolv::DNS
- Inherits:
-
Object
- Object
- Resolv::DNS
- Defined in:
- lib/resolv.rb
Overview
Resolv::DNS is a DNS stub resolver.
Information taken from the following places:
-
STD0013
-
RFC 1035
-
etc.
Defined Under Namespace
Modules: Label, OpCode, RCode Classes: Config, DecodeError, EncodeError, Message, Name, Query, Requester, Resource
Constant Summary collapse
- Port =
Default DNS Port
53
- UDPSize =
Default DNS UDP packet size
512
- RequestID =
:nodoc:
{}
- RequestIDMutex =
:nodoc:
Mutex.new
Class Method Summary collapse
-
.allocate_request_id(host, port) ⇒ Object
:nodoc:.
-
.bind_random_port(udpsock, bind_host = "0.0.0.0") ⇒ Object
:nodoc:.
-
.free_request_id(host, port, id) ⇒ Object
:nodoc:.
-
.open(*args) ⇒ Object
Creates a new DNS resolver.
-
.random(arg) ⇒ Object
:nodoc:.
-
.rangerand(range) ⇒ Object
:nodoc:.
Instance Method Summary collapse
-
#close ⇒ Object
Closes the DNS resolver.
-
#each_address(name) ⇒ Object
Iterates over all IP addresses for
name
retrieved from the DNS resolver. -
#each_name(address) ⇒ Object
Iterates over all hostnames for
address
retrieved from the DNS resolver. -
#each_resource(name, typeclass, &proc) ⇒ Object
Iterates over all
typeclass
DNS resources forname
. -
#extract_resources(msg, name, typeclass) ⇒ Object
:nodoc:.
-
#getaddress(name) ⇒ Object
Gets the IP address of
name
from the DNS resolver. -
#getaddresses(name) ⇒ Object
Gets all IP addresses for
name
from the DNS resolver. -
#getname(address) ⇒ Object
Gets the hostname for
address
from the DNS resolver. -
#getnames(address) ⇒ Object
Gets all hostnames for
address
from the DNS resolver. -
#getresource(name, typeclass) ⇒ Object
Look up the
typeclass
DNS resource ofname
. -
#getresources(name, typeclass) ⇒ Object
Looks up all
typeclass
DNS resources forname
. -
#initialize(config_info = nil) ⇒ DNS
constructor
Creates a new DNS resolver.
-
#lazy_initialize ⇒ Object
:nodoc:.
-
#make_tcp_requester(host, port) ⇒ Object
:nodoc:.
-
#make_udp_requester ⇒ Object
:nodoc:.
Constructor Details
#initialize(config_info = nil) ⇒ DNS
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)
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# File 'lib/resolv.rb', line 333 def initialize(config_info=nil) @mutex = Mutex.new @config = Config.new(config_info) @initialized = nil end |
Class Method Details
.allocate_request_id(host, port) ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 605 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 |
.bind_random_port(udpsock, bind_host = "0.0.0.0") ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 629 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 |
.free_request_id(host, port, id) ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 617 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 |
.open(*args) ⇒ Object
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.
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# File 'lib/resolv.rb', line 298 def self.open(*args) dns = new(*args) return dns unless block_given? begin yield dns ensure dns.close end end |
.random(arg) ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 579 def self.random(arg) # :nodoc: begin SecureRandom.random_number(arg) rescue NotImplementedError rand(arg) end end |
.rangerand(range) ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 593 def self.rangerand(range) # :nodoc: base = range.begin len = range.end - range.begin if !range.exclude_end? len += 1 end base + random(len) end |
Instance Method Details
#close ⇒ Object
Closes the DNS resolver.
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# File 'lib/resolv.rb', line 352 def close @mutex.synchronize { if @initialized @initialized = false end } end |
#each_address(name) ⇒ Object
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
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# File 'lib/resolv.rb', line 390 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 |
#each_name(address) ⇒ Object
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.
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# File 'lib/resolv.rb', line 437 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 |
#each_resource(name, typeclass, &proc) ⇒ Object
Iterates over all typeclass
DNS resources for name
. See #getresource for argument details.
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# File 'lib/resolv.rb', line 493 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 = senders[[candidate, nameserver, port]] = requester.sender(msg, candidate, nameserver, port) 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 |
#extract_resources(msg, name, typeclass) ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 547 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 |
#getaddress(name) ⇒ Object
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
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# File 'lib/resolv.rb', line 366 def getaddress(name) each_address(name) {|address| return address} raise ResolvError.new("DNS result has no information for #{name}") end |
#getaddresses(name) ⇒ Object
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
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# File 'lib/resolv.rb', line 377 def getaddresses(name) ret = [] each_address(name) {|address| ret << address} return ret end |
#getname(address) ⇒ Object
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.
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# File 'lib/resolv.rb', line 413 def getname(address) each_name(address) {|name| return name} raise ResolvError.new("DNS result has no information for #{address}") end |
#getnames(address) ⇒ Object
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.
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# File 'lib/resolv.rb', line 424 def getnames(address) ret = [] each_name(address) {|name| ret << name} return ret end |
#getresource(name, typeclass) ⇒ Object
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.
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# File 'lib/resolv.rb', line 474 def getresource(name, typeclass) each_resource(name, typeclass) {|resource| return resource} raise ResolvError.new("DNS result has no information for #{name}") end |
#getresources(name, typeclass) ⇒ Object
Looks up all typeclass
DNS resources for name
. See #getresource for argument details.
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# File 'lib/resolv.rb', line 483 def getresources(name, typeclass) ret = [] each_resource(name, typeclass) {|resource| ret << resource} return ret end |
#lazy_initialize ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 339 def lazy_initialize # :nodoc: @mutex.synchronize { unless @initialized @config.lazy_initialize @initialized = true end } self end |
#make_tcp_requester(host, port) ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 543 def make_tcp_requester(host, port) # :nodoc: return Requester::TCP.new(host, port) end |
#make_udp_requester ⇒ Object
:nodoc:
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# File 'lib/resolv.rb', line 534 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 |