Class: Resolv::DNS

# File 'lib/resolv.rb', line 659

def self.bind_random_port(udpsock, bind_host="0.0.0.0") # :nodoc:
  begin
    port = random(1024..65535)
    udpsock.bind(bind_host, port)
  rescue Errno::EADDRINUSE, # POSIX
         Errno::EACCES, # SunOS: See PRIV_SYS_NFS in privileges(5)
         Errno::EPERM # FreeBSD: security.mac.portacl.port_high is configurable.  See mac_portacl(4).
    retry
  end
end

# File 'lib/resolv.rb', line 647

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

# File 'lib/resolv.rb', line 289

def self.open(*args)
  dns = new(*args)
  return dns unless block_given?
  begin
    yield dns
  ensure
    dns.close
  end
end

# File 'lib/resolv.rb', line 619

def self.random(arg) # :nodoc:
  begin
    SecureRandom.random_number(arg)
  rescue NotImplementedError
    rand(arg)
  end
end

# File 'lib/resolv.rb', line 405

def use_ipv6? # :nodoc:
  @config.lazy_initialize unless @config.instance_variable_get(:@initialized)

  use_ipv6 = @config.use_ipv6?
  unless use_ipv6.nil?
    return use_ipv6
  end

  begin
    list = Socket.ip_address_list
  rescue NotImplementedError
    return true
  end
  list.any? {|a| a.ipv6? && !a.ipv6_loopback? && !a.ipv6_linklocal? }
end

# File 'lib/resolv.rb', line 398

def each_address(name)
  if use_ipv6?
    each_resource(name, Resource::IN::AAAA) {|resource| yield resource.address}
  end
  each_resource(name, Resource::IN::A) {|resource| yield resource.address}
end

# File 'lib/resolv.rb', line 452

def each_name(address)
  case address
  when Name
    ptr = address
  when IPv4, IPv6
    ptr = address.to_name
  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

# File 'lib/resolv.rb', line 510

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 587

def extract_resources(msg, name, typeclass) # :nodoc:
  if typeclass < Resource::ANY
    n0 = Name.create(name)
    msg.each_resource {|n, ttl, data|
      yield data if n0 == n
    }
  end
  yielded = false
  n0 = Name.create(name)
  msg.each_resource {|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_resource {|n, ttl, data|
    if n0 == n
      case data
      when typeclass
        yield data
      end
    end
  }
end

# File 'lib/resolv.rb', line 516

def fetch_resource(name, typeclass)
  lazy_initialize
  truncated = {}
  requesters = {}
  udp_requester = begin
    make_udp_requester
  rescue Errno::EACCES
    # fall back to TCP
  end
  senders = {}

  begin
    @config.resolv(name) do |candidate, tout, nameserver, port|
      msg = Message.new
      msg.rd = 1
      msg.add_question(candidate, typeclass)

      requester = requesters.fetch([nameserver, port]) do
        if !truncated[candidate] && udp_requester
          udp_requester
        else
          requesters[[nameserver, port]] = make_tcp_requester(nameserver, port)
        end
      end

      unless sender = senders[[candidate, requester, nameserver, port]]
        sender = requester.sender(msg, candidate, nameserver, port)
        next if !sender
        senders[[candidate, requester, 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
          # Retry via TCP:
          truncated[candidate] = true
          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
    end
  ensure
    udp_requester&.close
    requesters.each_value { |requester| requester&.close }
  end
end

# File 'lib/resolv.rb', line 374

def getaddress(name)
  each_address(name) {|address| return address}
  raise ResolvError.new("DNS result has no information for #{name}")
end

# File 'lib/resolv.rb', line 385

def getaddresses(name)
  ret = []
  each_address(name) {|address| ret << address}
  return ret
end

# File 'lib/resolv.rb', line 428

def getname(address)
  each_name(address) {|name| return name}
  raise ResolvError.new("DNS result has no information for #{address}")
end

# File 'lib/resolv.rb', line 439

def getnames(address)
  ret = []
  each_name(address) {|name| ret << name}
  return ret
end

# File 'lib/resolv.rb', line 491

def getresource(name, typeclass)
  each_resource(name, typeclass) {|resource| return resource}
  raise ResolvError.new("DNS result has no information for #{name}")
end

# File 'lib/resolv.rb', line 500

def getresources(name, typeclass)
  ret = []
  each_resource(name, typeclass) {|resource| ret << resource}
  return ret
end

# File 'lib/resolv.rb', line 347

def lazy_initialize # :nodoc:
  @mutex.synchronize {
    unless @initialized
      @config.lazy_initialize
      @initialized = true
    end
  }
  self
end

# File 'lib/resolv.rb', line 578

def make_tcp_requester(host, port) # :nodoc:
  return Requester::TCP.new(host, port)
rescue Errno::ECONNREFUSED
  # Treat a refused TCP connection attempt to a nameserver like a timeout,
  # as Resolv::DNS::Config#resolv considers ResolvTimeout exceptions as a
  # hint to try the next nameserver:
  raise ResolvTimeout
end

# File 'lib/resolv.rb', line 569

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