Module: Reversed

Defined in:
lib/reversed.rb,
lib/reversed/version.rb

Constant Summary collapse

VERSION = 
"0.4.1"

Class Method Summary collapse

Class Method Details

.lookup(ip, timeout: 5, nameservers: nil, fallback: true) ⇒ Object 



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# File 'lib/reversed.rb', line 11

def self.lookup(ip, timeout: 5, nameservers: nil, fallback: true)
  ip = ip.to_s
  unless ip.empty?
    begin
      # ensure valid ip
      ip = IPAddr.new(ip)
    rescue IPAddr::InvalidAddressError
      raise ArgumentError, "Invalid IP"
    end

    options = {
      retry_number: 3,
      udp_timeout: timeout
    }
    options[:nameservers] = nameservers if nameservers
    begin
      resolver = Net::DNS::Resolver.new(options).search(ip.reverse, Net::DNS::PTR)
      answer = resolver.answer.first
      if !answer && fallback
        answer = resolver.authority.first
      end
      if answer && !answer.value.empty?
        answer.value.split(" ").first[0..-2]
      end
    rescue Net::DNS::Resolver::NoResponseError
      nil
    rescue Errno::EAFNOSUPPORT
      options[:use_tcp] = true
      options[:tcp_timeout] = timeout
      retry
    end
  end
end