class Resolv

Resolv is a thread-aware DNS resolver library written in Ruby. Resolv can handle multiple DNS requests concurrently without blocking the entire Ruby interpreter.

See also resolv-replace.rb to replace the libc resolver with Resolv.

Resolv can look up various DNS resources using the DNS module directly.

Examples:

p Resolv.getaddress "www.ruby-lang.org"
p Resolv.getname "210.251.121.214"

Resolv::DNS.open do |dns|
  ress = dns.getresources "www.ruby-lang.org", Resolv::DNS::Resource::IN::A
  p ress.map(&:address)
  ress = dns.getresources "ruby-lang.org", Resolv::DNS::Resource::IN::MX
  p ress.map { |r| [r.exchange.to_s, r.preference] }
end

Bugs¶ ↑

NIS is not supported.
/etc/nsswitch.conf is not supported.

Constants

AddressRegex: Address Regexp to use for matching IP addresses.
DefaultResolver: Default resolver to use for Resolv class methods.
VERSION

Public Class Methods

each_address (name, &block)

Source

# File lib/resolv.rb, line 59
def self.each_address(name, &block)
  DefaultResolver.each_address(name, &block)
end

Iterates over all IP addresses for name.

each_name (address, &proc)

Source

# File lib/resolv.rb, line 80
def self.each_name(address, &proc)
  DefaultResolver.each_name(address, &proc)
end

Iterates over all hostnames for address.

getaddress (name)

Source

# File lib/resolv.rb, line 45
def self.getaddress(name)
  DefaultResolver.getaddress(name)
end

Looks up the first IP address for name.

getaddresses (name)

Source

# File lib/resolv.rb, line 52
def self.getaddresses(name)
  DefaultResolver.getaddresses(name)
end

Looks up all IP address for name.

getname (address)

Source

# File lib/resolv.rb, line 66
def self.getname(address)
  DefaultResolver.getname(address)
end

Looks up the hostname of address.

getnames (address)

Source

# File lib/resolv.rb, line 73
def self.getnames(address)
  DefaultResolver.getnames(address)
end

Looks up all hostnames for address.

new (resolvers=nil, use_ipv6: nil)

Source

# File lib/resolv.rb, line 87
def initialize(resolvers=nil, use_ipv6: nil)
  @resolvers = resolvers || [Hosts.new, DNS.new(DNS::Config.default_config_hash.merge(use_ipv6: use_ipv6))]
end

Creates a new Resolv using resolvers.

Public Instance Methods

each_address (name) { |name| ... }

Source

# File lib/resolv.rb, line 111
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

Iterates over all IP addresses for name.

each_name (address) { |name| ... }

Source

# File lib/resolv.rb, line 146
def each_name(address)
  yielded = false
  @resolvers.each {|r|
    r.each_name(address) {|name|
      yield name.to_s
      yielded = true
    }
    return if yielded
  }
end

Iterates over all hostnames for address.

getaddress (name)

Source

# File lib/resolv.rb, line 94
def getaddress(name)
  each_address(name) {|address| return address}
  raise ResolvError.new("no address for #{name}")
end

Looks up the first IP address for name.

getaddresses (name)

Source

# File lib/resolv.rb, line 102
def getaddresses(name)
  ret = []
  each_address(name) {|address| ret << address}
  return ret
end

Looks up all IP address for name.

getname (address)

Source

# File lib/resolv.rb, line 129
def getname(address)
  each_name(address) {|name| return name}
  raise ResolvError.new("no name for #{address}")
end

Looks up the hostname of address.

getnames (address)

Source

# File lib/resolv.rb, line 137
def getnames(address)
  ret = []
  each_name(address) {|name| ret << name}
  return ret
end

Looks up all hostnames for address.