#!/usr/bin/env python

import subprocess
import re
import time
import hashlib

timeout   = 300
f_current = '/var/db/connect.current'
f_gone    = '/var/db/connect.gone'

def interfaces():
  infs=[]
  cmd = ['/usr/bin/grep','range','/usr/local/etc/dnsmasq.conf']
  output = subprocess.Popen(cmd, stdout=subprocess.PIPE).communicate()[0]
  for line in output.strip().split('\n'):
    inf = line.split('=')[1].split(',')[0]
    inf = inf.replace('ath', 'wlan')
    infs.append(inf)
  return infs

def get_arp_list(inf):
  arp = {}
  output = subprocess.Popen(['/usr/sbin/arp','-na'], stdout=subprocess.PIPE).communicate()[0]
  for i in inf:
    for line in output.strip().split('\n'):
      if not 'expires' in line:
        continue
      if i not in line:
        continue
      t = re.split('[ ()]',line)
      ip, mac, time, inf = t[2],t[5],t[10],t[7]
      arp[ip]=(mac,time,inf)
  return arp

def get_current():
  try:
    file = open(f_current, 'r')
    current=file.readlines()
    file.close()
    currentmacs = []
    for i in current:
      currentmacs.append((i.split()[0],i.split()[1],i.split()[2]))
  except IOError:
    return ()
  return currentmacs

def write_new(clients):
  currentmacs = get_current()
  t = int(time.time())
  currentmacs=get_current()
  file = open(f_current, 'a')

  for dummy, data in clients.iteritems(): 
    b=False
    for cur in currentmacs:
      if data[0] == cur[0]: 
        b=True
        break
    if b:
      continue
    t2 = t + int(data[1]) - timeout 
    file.write("%s %s %s\n" % (data[0],t2,data[2]))
  file.close()

def diff_clients(arp, reg):
  gone = []
  for client in reg:
    b=False
    for i in arp.values(): 
      if client[0] == i[0] and client[2] == i[2]:
        b=True
        break
    if b:
      continue
    gone.append(client)
  return gone

def clients_disc_gone(gone):
  t = int(time.time())
  file = open(f_gone, 'a')
  for client in gone:
    t2 = t - ((t - int(client[1])) % timeout)
    hash = ""
    hash = hashlib.md5()
    hash.update(client[0])
    macshort=client[0][0:8]
    file.write("%s %s %s %s %s %s\n" % (hash.hexdigest(), client[1], t2, client[2], macshort, client[0]))
  file.close()

def clients_disc_current(gone,reg):
  new = []
  for client in reg:
    b=False
    for i in gone:
      if client[0] == i[0]:
        b=True
        break
    if b:
      continue
    new.append(client)
  file=open(f_current, 'w') 
  for line in new:
    file.write("%s %s %s\n" % (line[0], line[1], line[2]))
  file.close()

# Get arp list 
arp  = get_arp_list(interfaces())

# Write new arp entries to current
write_new(arp)

# Get all entries in current
reg = get_current()

# What is not in arp but is in current
gone = diff_clients(arp, reg)

# Write those entries to gone
clients_disc_gone(gone)

# Remove those entries from current
clients_disc_current(gone,reg)