Backend

This is backend part of new devices detection.

It just connects to pakond, parses received json and stores local MAC addresses seen in flows. Addresses are stored in json format in file, which is normally saved every 30 minutes (or when new device is detected).

macAddrStore.py

-#!/usr/bin/python
+#
+#    DevDetect - small utility to detect new devices on local network
+#    Copyright (C) 2017 CZ.NIC, z.s.p.o. (http://www.nic.cz/)
+#
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation; either version 2 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License along
+#    with this program; if not, write to the Free Software Foundation, Inc.,
+#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
 # -*- coding: utf-8 -*-
 
 import time
@@ -8,6 +25,7 @@ import os
 from threading import Timer
 
 class macAddrStore():
+	#keeps MAC addresses as dictionary, MAC address is the key, timestamp is the value
 	def __init__(self):
 		self.__load()
 		self.save_interval=30*60 #TBD: move to configuration
@@ -17,9 +35,12 @@ class macAddrStore():
 		t.start()
 		
 	def __del__(self):
+		#save values on program exit
 		self.__save()
 
 	def update(self, mac):
+		#update MAC address (its timetamp)
+		#if it wasn't seen before, register it (also save file immdiatelly) and create notification for user
 		if mac in self.known:
 			self.known[mac]=int(time.time())
 		else:
@@ -29,6 +50,8 @@ class macAddrStore():
 			os.system("/usr/bin/create_notification -s news 'Ve vasi siti se objevilo nove zarizeni (MAC adresa %s)' 'New device (MAC address %s) appeared on your network.'" % (mac, mac)) #TBD: Czech non-ascii characters...
 
 	def __save(self):
+		#save known MAC addresses to file
+		#to prevent file corruption, MAC addresses are at first written to temporary files which is then moved to correct location
 		f = open('/tmp/known_macs.txt', 'w')
 		print >>f, json.dumps(self.known)
 		print json.dumps(self.known)
@@ -36,6 +59,7 @@ class macAddrStore():
 		shutil.move('/tmp/known_macs.txt', '/usr/share/known_macs.txt')
 
 	def __load(self):
+		#load addresses (if they exist)
 		try:
 			f = open('/usr/share/known_macs.txt', 'r')
 			self.known=json.load(f)
@@ -44,6 +68,8 @@ class macAddrStore():
 			self.known={}
 
 	def __timeout(self):
+		#save MAC addresses to file
+		#also clean MAC addresses that were inactive for too long
 		for mac in self.known.keys():
 			if self.known[mac] < int(time.time()) - self.mac_timeout:
 				del self.known_macs[mac]