no-ip-daemon.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os, time, json, urllib2, base64, re


_SETTINGS = dict()
_OLD_IP = '1.1.1.1'

def createDaemon():
  global _SETTINGS, _OLD_IP
  """ 
      This function create a service/Daemon that will execute a det. task
  """
  jsonfile = open('settings.json')
  _SETTINGS = json.load(jsonfile)
  jsonfile.close()
  #print json.dumps(_SETTINGS)
 
  try:
    pidfile = open(_SETTINGS['pidfile'])
    print 'Error: pid file already exists'
    pidfile.close()
    os._exit(1)
  except IOError, error:
    print 'Forking new process'

  try:
    # Store the Fork PID

    pid = os.fork()

    if pid > 0:
      print 'PID: %d' % pid
      with open(_SETTINGS['pidfile'], 'w') as pidfile:
        pidfile.write(str(pid))
        pidfile.close()
      os._exit(0)

  except OSError, error:
    print 'Unable to fork. Error: %d (%s)' % (error.errno, error.strerror)
    os._exit(1)

  doTask()

def doTask():
  global _OLD_IP
  """ 
      This function create a task that will be a daemon
  """
  # Open the file in write mode
  file = open(_SETTINGS['log'], 'w')

  # Start the write
  while True:
    _new_ = urllib2.urlopen(_SETTINGS['ipresolve']).read().strip()
    print >> file, time.ctime() + ' new ip: ' + _new_ + ' old ip: ' + _OLD_IP
    print >> file, 'next update check in %d seconds.' % _SETTINGS['interval']

    if _new_ == _OLD_IP:
      print >> file, 'ip has not changed. no need to update.'
    else:
      print >> file, 'ip has changed. trying to update.'
      _updateurl_ = _SETTINGS['updateurl']    
      
      """ Update current public ip """
      _url_ = _updateurl_.format(hostname=_SETTINGS['hostname'], ip=_new_)
      _user_data_ = "Basic " + (_SETTINGS['username'] + ":" + _SETTINGS['password']).encode("base64").rstrip()
      
      print >> file, _url_ + " " + _user_data_
      
      req = urllib2.Request(_url_)
      req.add_header("Authorization", _user_data_)
      req.add_header('User-agent', 'Python no-ip-daemon v1.0 neskola@gmail.com')
      
      print >> file, req
      
      try:
        res = urllib2.urlopen(req)
        res_txt = res.read()
        res_code = res.getcode()

        print >> file, 'response is ' + res_txt + ' ' + str(res_code) 
        if re.match('^(good)|(nochg).*', res_txt):
          print >> file, '... Succeed'
          _OLD_IP = _new_
        else:
          print >> file, '... Failed. Exiting.'
          file.flush()
          file.close()
          os._exit(1)
      except urllib2.HTTPError as e:
        print >> file, "HTTP exception {0},{1}".format(e.code, e.reason) 
        file.flush()
        file.close()
        os._exit(1)
            
    file.flush()    
    time.sleep(_SETTINGS['interval'])

  # Close the file
  file.close()

if __name__ == '__main__':

  # Create the Daemon
  createDaemon()