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class Resolv::DNS
Resolv::DNS is a DNS stub resolver.
Information taken from the following places:
STD0013
RFC 1035
etc.
Constants
Public Class Methods
# File lib/resolv.rb, line 336
def initialize(config_info=nil)
@mutex = Mutex.new
@config = Config.new(config_info)
@initialized = nil
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)
Public Instance Methods
# File lib/resolv.rb, line 370
def close
@mutex.synchronize {
if @initialized
@initialized = false
end
}
end
Closes the DNS resolver.
# File lib/resolv.rb, line 408
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 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 455
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 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 511
def each_resource(name, typeclass, &proc)
fetch_resource(name, typeclass) {|reply, reply_name|
extract_resources(reply, reply_name, typeclass, &proc)
}
end
Iterates over all typeclass
DNS resources for name
. See getresource for argument details.
# File lib/resolv.rb, line 517
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
# File lib/resolv.rb, line 384
def getaddress(name)
each_address(name) {|address| return address}
raise ResolvError.new("DNS result has no information for #{name}")
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 395
def getaddresses(name)
ret = []
each_address(name) {|address| ret << address}
return ret
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 431
def getname(address)
each_name(address) {|name| return name}
raise ResolvError.new("DNS result has no information for #{address}")
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 442
def getnames(address)
ret = []
each_name(address) {|name| ret << name}
return ret
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 492
def getresource(name, typeclass)
each_resource(name, typeclass) {|resource| return resource}
raise ResolvError.new("DNS result has no information for #{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::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 501
def getresources(name, typeclass)
ret = []
each_resource(name, typeclass) {|resource| ret << resource}
return ret
end
Looks up all typeclass
DNS resources for name
. See getresource for argument details.
# File lib/resolv.rb, line 353
def timeouts=(values)
@config.timeouts = values
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
Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.