update your CloudFlare record when your IP changes

cf-l-update

#!/usr/bin/env python3

import fcntl
import socket
import struct
import json
import urllib.request

from dns.resolver import Resolver

def get_my_ip(ifname):
  ifname = ifname.encode('ascii')
  s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  # 0x8915 是 SIOCGIFADDR
  ip = socket.inet_ntoa(fcntl.ioctl(s.fileno(), 0x8915, struct.pack('256s', ifname[:15]))[20:24])
  return ip

def main():
  myip = get_my_ip('ppp0')

  ns_ip = socket.gethostbyname('kami.ns.cloudflare.com')
  r = Resolver()
  r.nameservers[:] = [ns_ip]
  ans = r.query('你的域名')
  ip = list(ans)[0].address

  if ip == myip:
    return

  print('updating IP: %s -> %s' % (ip, myip))

  data = {
    'id': '你的域名那项对应的 ID',
    'type': 'A',
    'name': '你的域名',
    'content': myip,
    'proxied': False,
  }

  req = urllib.request.Request(
    'https://api.cloudflare.com/client/v4/zones/你的域名（zone）对应的 ID/dns_records/你的域名那项对应的 ID',
    headers = {
      'X-Auth-Email': '你的登录名',
      'X-Auth-Key': '你的 API key',
      'Content-Type': 'application/json',
    },
    data = json.dumps(data).encode('utf-8'),
    method = 'PUT',
  )
  res = urllib.request.urlopen(req)
  data = res.read()
  ans = json.loads(data.decode('utf-8'))
  if not ans['success']:
    raise Exception(ans)

if __name__ == '__main__':
  main()