ACMS/Server/ACL.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
A simple class to manage an ACL.
"""


import os
import json

from fileCommands import DATA_PATH
from CommandException import CommandException


__author__ = "HorlogeSkynet"
__copyright__ = "Copyright 2017, ACMS"
__license__ = "GPLv3"
__status__ = "Development"
__date__ = "02/23/2017"


class AccessControlList():

	"""
	The only attribute (useful) in this class is the dictionary, and it is declared as a "private attribute".

	The dictionary is constructed as a JSON file as below (a piece of advice: use a JSON editor):
	{"groups": {"dentistes": ["Marie", "Xavier"], "chirurgien": ["Jules"], "pédiatres": ["Jules"]}, "files": {"filename_2": {"owner": "Marie", "write": ["dentistes"], "read": ["Xavier"], "execute": ["pédiatres"]}, "filename_1": {"owner": "Marie", "write": ["pédiatres", "dentistes"], "read": ["Xavier"], "execute": ["chirurgien"]}}}

	During the class initialization, the dictionary is filled with data present in the backup file.
	Each authorized and validated action implies the dumping of the new dictionary in the backup file (persistent data).
	"""

	def __init__(self):
		self.__FILE = 'Server/Data/passwd.json'

		self.__data = {"groups": {}, "files": {}}

		self.loadFromFile()

		self.checkIntegrity()

	def loadFromFile(self):
		if os.path.exists(self.__FILE):
			with open(self.__FILE, 'r') as file:
				try:
					self.__data = json.load(file)

				except json.JSONDecodeError as e:
					print("The backup file (\"" + self.__FILE + "\") looks corrupted (" + e.msg + ' [' + str(e.lineno) + '; ' + str(e.colno) + ']' + "). Contact an administrator.")

				finally:
					file.close()

	def saveToFile(self):
			with open(self.__FILE, 'w+') as file:
				try:
					json.dump(self.__data, file, ensure_ascii=False, indent='\t')

				except (TypeError, json.JSONEncodeError):
					print("An invalid object is present in the ACL dictionary, we\'d advise you to fix the backup in the \"" + self.__FILE + "\" file, and import it.")

				finally:
					file.close()

	def checkIntegrity(self):
		results = []

		def browseFiles(path):
			for file in os.listdir(path):
				temp = path + file
				if os.path.isdir(path + file):
					results.append(temp + '/')
					browseFiles(temp + '/')

				else:
					results.append(temp)

		# Browses each file in the database and stores them into a list
		browseFiles(DATA_PATH)

		# Computes the symmetrical differences between the files browsed and the ones present in the ACL
		differences = set(results).symmetric_difference(list(self.__data['files'].keys()))
		if len(differences) != 0:
			for difference in differences:
				print("\nThe element \"" + difference + "\" is not present in the ACL or into the database. Please fix this difference.\n")

			quit()

		else:
			print("\nYour database is clean ! Let\'s proceed.")

	def isAllowedToOn(self, user, action, file):
		try:
			# This 'user' is allowed to perform this 'action' on this 'file' if: He's the owner, he has access, its group had access
			if user == self.__data['files'][file]['owner'] or user in self.__data['files'][file][action] or [group in self.__data['files'][file][action] for group in getGroupsByUser(self.__data['groups'], user)].count(True) > 0:
				return True

			else:
				return False

		except:
			return None

	def addUserInGroup(self, user, group):
		try:
			if self.__data['groups'][group].count(user) == 0:
				self.__data['groups'][group].append(user)
				self.saveToFile()

			else:
				raise CommandException("This user is already in this group !")

		except:
			raise CommandException("Can\'t add this user into this group.")

	def removeUserFromGroup(self, user, group):
		try:
			self.__data['groups'][group].remove(user)
			self.saveToFile()

		except:
			raise CommandException("Can\'t remove this user from this group.")

	def addFile(self, user, file, read=[], write=[], execute=[]):
		if list(self.__data['files'].keys()).count(file) == 0:
			# Only owner and its group (plus selected persons) can access this file
			read.extend(getGroupsByUser(self.__data['groups'], user))

			# Only owner (plus selected persons) can modify this file
			# write.append(user) (Not mandatory, the own test is done)

			# Only owner and its group (plus selected persons) can execute this file
			execute.extend(getGroupsByUser(self.__data['groups'], user))

			self.__data['files'][file] = {'owner': user, 'read': read, 'write': write, 'execute': execute}

			self.saveToFile()

		else:
			raise CommandException("This file already exist !")

	def deleteFile(self, user, file):
		try:
			del self.__data['files'][file]
			self.saveToFile()

		except:
			raise CommandException("This file does not exist...")

	def renameFile(self, user, file, newFileName):
		try:
			if list(self.__data['files'].keys()).count(newFileName) == 0:
				self.__data['files'][newFileName] = self.__data['files'][file]
				del self.__data['files'][file]
				self.saveToFile()

			else:
				raise CommandException("A file with the new name specified already exist !")

		except:
			raise CommandException("An error occurred...")

	def changeRightsOnFile(self, user, file, read=[], write=[], execute=[]):
		try:
			if user == self.__data['files'][file]['owner']:
				self.__data['files'][file] = {'owner': user, 'read': read, 'write': write, 'execute': execute}
				self.saveToFile()

			else:
				raise CommandException("You\'re not allowed to perform this operation !")

		except:
			raise CommandException("This file does not exist...")

	def changeOwnOnFile(self, user, file, newUser):
		try:
			if user == self.__data['files'][file]['owner']:
				self.__data['files'][file]['owner'] = newUser
				self.saveToFile()

			else:
				raise CommandException("You\'re not allowed to perform this operation !")

		except:
			raise CommandException("This file does not exist...")

	def isAdministrator(self, user):
		if "administrator" in getGroupsByUser(self.__data['groups'], user):
			return True
		else:
			return False


#################
# Miscellaneous #
#################

def getGroupsByUser(groups, user):
	userGroups = []

	try:
		for group, members in groups.items():
			if user in members:
				userGroups.append(group)

	except:
		pass

	finally:
		return userGroups