Pythonでビット操作してみる

スクリプト

#!/usr/bin/env python3

import sys


def format_bit_image(value):
  bit_str = format(value, "b").zfill(32)
  return " ".join([bit_str[0:8], bit_str[8:16], bit_str[16:24], bit_str[24:32]])


def get_4octets(str):
  int_list = [int(x) for x in str.split(".")]  # using list comprehension
  return int_list[0] << 24 | int_list[1] << 16 | int_list[2] << 8 | int_list[3]


def get_str_expression(value):
  p = []
  p.append(value >> 24 & 0xFF)
  p.append(value >> 16 & 0xFF)
  p.append(value >> 8 & 0xFF)
  p.append(value & 0xFF)
  str_p = [str(x) for x in p]

  return ".".join(str_p)


def show_info(label, value):
  print(
      "%-14s = %d {%s} %s [%s]"
      % (label, value, format_bit_image(value), hex(value), get_str_expression(value))
  )


if len(sys.argv) != 3:
  print("Usage: %s [IP address] [Netmask]" % sys.argv[0])
  exit(1)

ip_addr = get_4octets(sys.argv[1])
netmask = get_4octets(sys.argv[2])
show_info("ip_addr", ip_addr)
show_info("netmask", netmask)
network_addr = ip_addr & netmask
show_info("network_addr", network_addr)
broadcast_addr = ip_addr | (~netmask & 0xFFFFFFFF)
show_info("broadcast_addr", broadcast_addr)

実行結果

% printf "%d\n" 0xf0         
240
% ./network_address.py 192.168.125.130 255.255.255.240
ip_addr        = 3232267650 {11000000 10101000 01111101 10000010} 0xc0a87d82 [192.168.125.130]
netmask        = 4294967280 {11111111 11111111 11111111 11110000} 0xfffffff0 [255.255.255.240]
network_addr   = 3232267648 {11000000 10101000 01111101 10000000} 0xc0a87d80 [192.168.125.128]
broadcast_addr = 3232267663 {11000000 10101000 01111101 10001111} 0xc0a87d8f [192.168.125.143]
%