Resolv::DNS
is a DNS
stub resolver.
Information taken from the following places:
-
STD0013
-
RFC 1035
-
etc.
# File tmp/rubies/ruby-2.4.10/lib/resolv.rb, line 334
def initialize(config_info=nil)
@mutex = Thread::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)
# File tmp/rubies/ruby-2.4.10/lib/resolv.rb, line 299
def self.open(*args)
dns = new(*args)
return dns unless block_given?
begin
yield dns
ensure
dns.close
end
end
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.
# File tmp/rubies/ruby-2.4.10/lib/resolv.rb, line 368
def close
@mutex.synchronize {
if @initialized
@initialized = false
end
}
end
Closes the DNS
resolver.
# File tmp/rubies/ruby-2.4.10/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 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 tmp/rubies/ruby-2.4.10/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 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 tmp/rubies/ruby-2.4.10/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
Iterates over all typeclass
DNS
resources for name
. See getresource
for argument details.
# File tmp/rubies/ruby-2.4.10/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
# File tmp/rubies/ruby-2.4.10/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 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 tmp/rubies/ruby-2.4.10/lib/resolv.rb, line 393
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 tmp/rubies/ruby-2.4.10/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 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 tmp/rubies/ruby-2.4.10/lib/resolv.rb, line 440
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 tmp/rubies/ruby-2.4.10/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
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 tmp/rubies/ruby-2.4.10/lib/resolv.rb, line 499
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 tmp/rubies/ruby-2.4.10/lib/resolv.rb, line 351
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