class Resolv::DNS
Resolv::DNS is a DNS stub resolver.
Information taken from the following places:
-
STD0013
-
RFC 1035
-
etc.
Constants
Public Class Methods
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)
# File lib/resolv.rb, line 334 def initialize(config_info=nil) @mutex = Mutex.new @config = Config.new(config_info) @initialized = nil end
Public Instance Methods
Closes the DNS resolver.
# File lib/resolv.rb, line 368 def close @mutex.synchronize { if @initialized @initialized = false end } 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
# File lib/resolv.rb, line 406 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
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.
# File lib/resolv.rb, line 453 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
Iterates over all typeclass
DNS
resources for name
. See getresource for argument details.
# File lib/resolv.rb, line 509 def each_resource(name, typeclass, &proc) fetch_resource(name, typeclass) {|reply, reply_name| extract_resources(reply, reply_name, typeclass, &proc) } end
# File lib/resolv.rb, line 515 def fetch_resource(name, typeclass) 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 yield(reply, reply_name) 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
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
# File lib/resolv.rb, line 382 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
# File lib/resolv.rb, line 393 def getaddresses(name) ret = [] each_address(name) {|address| ret << address} return ret end
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.
# File lib/resolv.rb, line 429 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.
# File lib/resolv.rb, line 440 def getnames(address) ret = [] each_name(address) {|name| ret << name} return ret 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::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
Returned resource is represented as a Resolv::DNS::Resource instance, i.e. Resolv::DNS::Resource::IN::A.
# File lib/resolv.rb, line 490 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.
# File lib/resolv.rb, line 499 def getresources(name, typeclass) ret = [] each_resource(name, typeclass) {|resource| ret << resource} return ret end
Sets the resolver timeouts. This may be a single positive number or an
array of positive numbers representing timeouts in seconds. If an array is
specified, a DNS request will retry and wait for
each successive interval in the array until a successful response is
received. Specifying nil
reverts to the default timeouts:
- 5, second = 5 * 2 / nameserver_count, 2 * second, 4 * second
-
Example:
dns.timeouts = 3
# File lib/resolv.rb, line 351 def timeouts=(values) @config.timeouts = values end