IPAddr#private?

# File tmp/rubies/ruby-4.0.0/lib/ipaddr.rb, line 309
def private?
  case @family
  when Socket::AF_INET
    @addr & 0xff000000 == 0x0a000000 ||    # 10.0.0.0/8
      @addr & 0xfff00000 == 0xac100000 ||  # 172.16.0.0/12
      @addr & 0xffff0000 == 0xc0a80000     # 192.168.0.0/16
  when Socket::AF_INET6
    @addr & 0xfe00_0000_0000_0000_0000_0000_0000_0000 == 0xfc00_0000_0000_0000_0000_0000_0000_0000 ||
      (@addr & 0xffff_0000_0000 == 0xffff_0000_0000 && (
        @addr & 0xff000000 == 0x0a000000 ||  # ::ffff:10.0.0.0/8
        @addr & 0xfff00000 == 0xac100000 ||  # ::ffff::172.16.0.0/12
        @addr & 0xffff0000 == 0xc0a80000     # ::ffff::192.168.0.0/16
      ))
  else
    raise AddressFamilyError, "unsupported address family"
  end
end