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138 lines
3.7 KiB
138 lines
3.7 KiB
import hashlib
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class User:
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def __init__(self, username, password):
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"""Create a new user object. The password will be encrypted before
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storing"""
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self.username = username
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self.password = self._encrypt_pw(password)
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self.is_logged_in = False
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def _encrypt_pw(self, password):
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"""Encrypt the password with the username and return the sha digest."""
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hash_string = self.username + password
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hash_string = hash_string.encode("utf8")
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return hashlib.sha256(hash_string).hexdigest()
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def check_password(self, password):
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"""Return True if the password is valid for this user,
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False otherwise"""
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encrypted = self._encrypt_pw(password)
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return encrypted == self.password
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class Authenticator:
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def __init__(self):
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"""Construct an authenticator to manage users logging in and out.
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The User objects are stored in a simple dictionary"""
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self.users = {}
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def add_user(self, username, password):
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"""Add a User object with given username & password to the users
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dictionary after checking if given username & password are valid"""
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if username in self.users:
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raise UsernameAlreadyExists(username)
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if len(password) < 6:
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raise PasswordTooShort(username)
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self.users[username] = User(username, password)
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def login(self, username, password):
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try:
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user = self.users[username]
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except KeyError:
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raise InvalidUsername(username)
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if not user.check_password(password):
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raise InvalidPassword(username, user)
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user.is_logged_in = True
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return True
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def is_logged_in(self, username):
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if username in self.users:
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return self.users[username].is_logged_in
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return False
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authenticator = Authenticator()
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class Authorizor():
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def __init__(self, authenticator):
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self.authenticator = authenticator
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self.permissions = {}
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def add_permission(self, perm_name):
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"""Create a new permission that users can be added to"""
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try:
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perm_set = self.permissions[perm_name]
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except KeyError:
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self.permissions[perm_name] = set()
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else:
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raise PermissionError("Permission exists")
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def permit_user(self, perm_name, username):
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"""Grant the given permission to the given user"""
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try:
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perm_set = self.permissions[perm_name]
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except KeyError:
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raise PermissionError("Permission does not exist")
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else:
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if username not in self.authenticator.users:
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raise InvalidUsername(username)
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perm_set.add(username)
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def check_permission(self, perm_name, username):
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if not self.authenticator.is_logged_in(username):
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raise NotLoggedInError(username)
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try:
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perm_set = self.permissions[perm_name]
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except KeyError:
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raise PermissionError("Permission does not exist")
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if username not in perm_set:
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raise NotPermittedError(username)
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else:
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return True
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authorizor = Authorizor(authenticator)
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# Exception classes
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class AuthException(Exception):
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def __init__(self, username, user=None):
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super().__init__(username, user)
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self.username = username
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self.user = user
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class UsernameAlreadyExists(AuthException):
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pass
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class PasswordTooShort(AuthException):
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pass
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class InvalidUsername(AuthException):
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pass
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class InvalidPassword(AuthException):
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pass
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class NotLoggedInError(AuthException):
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pass
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class NotPermittedError(AuthException):
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pass
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class PermissionError(Exception):
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pass
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