17.1. Recap About

17.1.1. Assignments

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Recap About EtcPasswdUsername
# - Difficulty: medium
# - Lines: 11
# - Minutes: 13

# %% English
# 1. Create function `get_username`:
#    - parameter: `uid` (user ID)
#    - return: `username`
# 2. Run doctests - all must succeed

# %% Polish
# 1. Stwórz funkcję `get_username`:
#    - parametr: `uid` (user ID)
#    - zwraca: `username`
# 2. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> get_username(0)
'root'
>>> get_username(1000)
'mwatney'
"""


DATA = """##
# Structure of `/etc/passwd` file:
# - user_login: username
# - user_password: 'x' indicates that shadow passwords are used (skip this field)
# - user_uid: user identification number
# - user_gid: group identification number
# - user_comment: comment ie. full name
# - user_home: path to home directory
# - user_shell: path to program run at login
##
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
nobody:x:99:99:Nobody:/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
mwatney:x:1000:1000:Mark Watney:/home/mwatney:/bin/bash
mlewis:x:1001:1001:Melissa Lewis:/home/mlewis:/bin/bash
rmartinez:x:1002:1002:Rick Martinez:/home/rmartinez:/bin/bash
avogel:x:1003:1003:Alex Vogel:/home/avogel:/bin/bash
bjohanssen:x:1004:1004:Beth Johanssen:/home/bjohanssen:/bin/bash
cbeck:x:1005:1005:Chris Beck:/home/cbeck:/bin/bash
"""

# Create function `get_username`:
# - parameter: `uid` (user ID)
# - return: `username`
# type: Callable[[int], str]
def get_username(user_id):
    ...

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Recap About EtcPasswd
# - Difficulty: medium
# - Lines: 15
# - Minutes: 13

# %% English
# 1. Create function `parse_passwd`:
#    - parameter: `username: str`
#    - return: dict with user data record
# 2. Split line by a colon (`:`):
#    - example: `mwatney:x:1000:1000:Mark Watney:/home/mwatney:/bin/bash`
#    - `user_login: str` - username
#    - `user_password: str` - 'x' indicates that shadow passwords are used
#    - `user_uid: int` - user identification number
#    - `user_gid: int` - group identification number
#    - `user_comment: str` - comment ie. full name
#    - `user_home: str` - path to home directory
#    - `user_shell: str` - path to program run at login
# 2. Run doctests - all must succeed

# %% Polish
# 1. Stwórz funkcję `parse_passwd`:
#    - parametr: `username: str`
#    - zwraca: dict z danymi użytkownika
# 2. Split line by a colon (`:`):
#    - przykład: `mwatney:x:1000:1000:Mark Watney:/home/mwatney:/bin/bash`
#    - `user_login: str` - nazwa użytkownika
#    - `user_password: str` - 'x' znaczy, że hasło jest w pliku shadow
#    - `user_uid: int` - numer identyfikacyjny użytkownika
#    - `user_gid: int` - numer identyfikacyjny grupy
#    - `user_comment: str` - komentarz, np. imię i nazwisko
#    - `user_home: str` - ścieżka do katalogu domowego
#    - `user_shell: str` - ścieżka do programu uruchamianego po zalogowaniu
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Hints
# - `len()`
# - `int()`
# - `str.splitlines()`
# - `str.isspace()`
# - `str.startswith()`
# - `str.split()`

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> from pprint import pprint

>>> pprint(parse_passwd('mwatney'), sort_dicts=False)
{'user_login': 'mwatney',
 'user_password': 'x',
 'user_uid': 1000,
 'user_gid': 1000,
 'user_comment': 'Mark Watney',
 'user_home': '/home/mwatney',
 'user_shell': '/bin/bash'}
"""

DATA = """##
# Structure of `/etc/passwd` file:
# - user_login: username
# - user_password: 'x' indicates that shadow passwords are used
# - user_uid: user identification number
# - user_gid: group identification number
# - user_comment: comment ie. full name
# - user_home: path to home directory
# - user_shell: path to program run at login
##
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
nobody:x:99:99:Nobody:/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
mwatney:x:1000:1000:Mark Watney:/home/mwatney:/bin/bash
mlewis:x:1001:1001:Melissa Lewis:/home/mlewis:/bin/bash
rmartinez:x:1002:1002:Rick Martinez:/home/rmartinez:/bin/bash
avogel:x:1003:1003:Alex Vogel:/home/avogel:/bin/bash
bjohanssen:x:1004:1004:Beth Johanssen:/home/bjohanssen:/bin/bash
cbeck:x:1005:1005:Chris Beck:/home/cbeck:/bin/bash
"""


# Create function `parse_passwd`:
# - parameter: `username: str`
# - return: dict with user data record
# type: Callable[[int], str]
def parse_passwd(username):
    ...

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Recap About EtcGroup
# - Difficulty: medium
# - Lines: 18
# - Minutes: 21

# %% English
# 1. Create function `parse_groups`:
#    - parameter: `username: str`
#    - return: list[str] with user groups
# 2. Split line by a colon (`:`):
#    - example: `user::1001:mwatney,mlewis,rmartinez`
#    - `group_name: str` - group name
#    - `group_password: str` - 'x' indicates that shadow passwords are used
#    - `group_gid: int` - group number
#    - `group_members: str` - comma-separated logins
# 3. Run doctests - all must succeed

# %% Polish
# 1. Stwórz funkcję `parse_groups`:
#    - parametr: `username: str`
#    - zwraca: list[str] z grupami użytkownika
# 2. Podziel line po dwukropku (`:`):
#    - przykład: `user::1001:mwatney,mlewis,rmartinez`
#    - `group_name: str` - nazwa grupy
#    - `group_password: str` - 'x' mówi, że hasło jest w pliku shadow
#    - `group_gid: int` - numer grupy
#    - `group_members: str` - loginy oddzielone przecinkami
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Hints
# - `len()`
# - `list[...]`
# - `... in tuple`
# - `str.splitlines()`
# - `str.isspace()`
# - `str.startswith()`
# - `str.split()`
# - `dict.get(...)`

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> from pprint import pprint

>>> result = parse_groups('mwatney')
>>> pprint(result)
['user', 'staff']

>>> result = parse_groups('root')
>>> pprint(result)
['root', 'bin', 'sys', 'adm', 'mail', 'daemon', 'sysadmin']
"""

DATA = """##
# Structure of `/etc/group` file:
#    - group_name: group name
#    - group_password: 'x' indicates that shadow passwords are used
#    - group_gid: group id
#    - group_members: comma-separated logins from `/etc/passwd`
##
root::0:root
other::1:
bin::2:root,bin,daemon
sys::3:root,bin,sys,adm
adm::4:root,adm,daemon
mail::6:root
daemon::12:root,daemon
sysadmin::14:root
user::1001:mwatney,mlewis,rmartinez,avogel,bjohanssen,cbeck
staff::1002:mwatney,mlewis,rmartinez,bjohanssen,cbeck
admin::1003:mlewis,bjohanssen
nobody::60001:
noaccess::60002:
nogroup::65534:
"""

# Create function `parse_groups`:
#  - parameter: `username: str`
#  - return: list[str] with user groups
# Split line by a colon (`:`):
#  - example: `user::1001:mwatney,mlewis,rmartinez`
#  - `group_name: str` - group name
#  - `group_password: str` - 'x' indicates that shadow passwords are used
#  - `group_gid: int` - group number
#  - `group_members: str` - comma-separated logins
# type: Callable[[int], str]
def parse_groups(username):
    ...

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Recap About EtcShadow
# - Difficulty: medium
# - Lines: 35
# - Minutes: 34

# %% English
# 1. Create function `parse_shadow`:
#    - parameter: `username: str`
#    - return: user password record as a dict
# 2. Split password field by `$`:
#    - algorithm (algorithm number, e.g. `6` is SHA-512)
#    - salt (value added to password)
#    - password hash (encoded password)
# 3. Run doctests - all must succeed

# %% Polish
# 1. Stwórz funkcję `parse_shadow`:
#    - parametr: `username: str`
#    - zwraca: dane hasła użytkownika jako dict
# 2. Podziel pole hasła po znaku `$`:
#    - algorytm (nr algorytmu, np. `6` to SHA-512)
#    - sól (wartość dodawana do hasła)
#    - hash hasła (zakodowane hasło)
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Hints
# - `len()`
# - `list[...]`
# - `... in tuple`
# - `str.splitlines()`
# - `str.isspace()`
# - `str.startswith()`
# - `str.split()`
# - `dict.get(...)`

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> from pprint import pprint

>>> result = parse_shadow('mwatney')
>>> pprint(result, sort_dicts=True)
{'account_expiration_date': '',
 'account_locked': False,
 'login': 'mwatney',
 'password_algorithm': 'SHA-512',
 'password_hash': 'bXGOh7dIfOWpUb/Tuqr7yQVCqL3UkrJns9.7msfvMg4ZO/PsFC5Tbt32PXAw9qRFEBs1254aLimFeNM8YsYOv.',
 'password_inactivity_period': '',
 'password_last_changed': '16550',
 'password_max_age': '',
 'password_min_age': '',
 'password_salt': '5H0QpwprRiJQR19Y',
 'password_warning_period': '',
 'reserved': ''}

>>> result = parse_shadow('mlewis')
>>> pprint(result, sort_dicts=True)
{'account_expiration_date': '',
 'account_locked': False,
 'login': 'mlewis',
 'password_algorithm': 'SHA-512',
 'password_hash': 'tgfvvFWJJ5FKmoXiP5rXWOjwoEBOEoAuBi3EphRbJqqjWYvhEM2wa67L9XgQ7W591FxUNklkDIQsk4kijuhE50',
 'password_inactivity_period': '',
 'password_last_changed': '16632',
 'password_max_age': '99999',
 'password_min_age': '0',
 'password_salt': 'P9zn0KwR',
 'password_warning_period': '7',
 'reserved': ''}
"""

DATA = """##
# Structure of `/etc/shadow` file:
#    - login: user login name
#    - password_encrypted: encrypted password (see below for more details)
#    - password_last_changed: days since 1970-01-01 password was last changed
#    - password_min_age: days before which password may not be changed
#    - password_max_age: days after which password must be changed
#    - password_warning_period: days before password is to expire that user is warned of pending password expiration
#    - password_inactivity_period: days after password expires that account is considered inactive and disabled
#    - account_expiration_date: days since 1970-01-01 when account will be disabled
#    - reserved: reserved for future use (skip this field)
#
# Password field (split by `$`):
#    - algorithm
#    - salt
#    - password hash
#
# Password algorithms:
#    - '1' - MD5
#    - '2a' - Blowfish
#    - '2y' - Blowfish
#    - '5' - SHA-256
#    - '6' - SHA-512
#
# Password special chars:
#    - ' '  - account unlocked, password is not required to log in
#    - '*'  - account locked, cannot be unlocked, and no password has ever been set
#    - '!!' - account locked, can be unlocked, waiting for initial password to be set by admin
#    - '!'  - account locked, can be unlocked, and no password has ever been set
#    - '!<password_hash>' - account locked, can be unlocked, but password is set
##
root:$6$Ke02nYgo.9v0SF4p$hjztYvo/M4buqO4oBX8KZTftjCn6fE4cV5o/I95QPekeQpITwFTRbDUBYBLIUx2mhorQoj9bLN8v.w6btE9xy1:16431:0:99999:7:::
bin:*:16431:0:99999:7:::
daemon:*:16431:0:99999:7:::
adm:*:16431:0:99999:7:::
shutdown:*:16431:0:99999:7:::
halt:*:16431:0:99999:7:::
nobody:*:16431:0:99999:7:::
sshd:*:16431:0:99999:7:::
mwatney:$6$5H0QpwprRiJQR19Y$bXGOh7dIfOWpUb/Tuqr7yQVCqL3UkrJns9.7msfvMg4ZO/PsFC5Tbt32PXAw9qRFEBs1254aLimFeNM8YsYOv.:16550::::::
mlewis:$6$P9zn0KwR$tgfvvFWJJ5FKmoXiP5rXWOjwoEBOEoAuBi3EphRbJqqjWYvhEM2wa67L9XgQ7W591FxUNklkDIQsk4kijuhE50:16632:0:99999:7:::
rmartinez:$1$.QKDPc5E$SWlkjRWexrXYgc98F.:12825:0:90:5:30:13096:
avogel:!!:16431:0:99999:7:::
bjohanssen:!:16431:0:99999:7:::
cbeck:*:16431:0:99999:7:::
"""

ALGORITHMS = {
    '1': 'MD5',
    '2a': 'Blowfish',
    '2y': 'Blowfish',
    '5': 'SHA-256',
    '6': 'SHA-512',
}


# Create function `parse_shadow`:
# - parameter: `username: str`
# - return: user password record as a dict
#
# Split password field by `$`:
# - algorithm (algorithm number, e.g. `6` is SHA-512)
# - salt (value added to password)
# - password hash (encoded password)
#
# type: Callable[[int], str]
def parse_shadow(username):
    ...