Setting up and reading the configruation file

2 files changed, 700 insertions, 21 deletions

diff --git a/pylintrc.toml b/pylintrc.toml
new file mode 100644
index 0000000..39bb057
--- /dev/null
+++ b/pylintrc.toml
@@ -0,0 +1,551 @@
+[tool.pylint.main]
+# Analyse import fallback blocks. This can be used to support both Python 2 and 3
+# compatible code, which means that the block might have code that exists only in
+# one or another interpreter, leading to false positives when analysed.
+# analyse-fallback-blocks =
+
+# Clear in-memory caches upon conclusion of linting. Useful if running pylint in
+# a server-like mode.
+# clear-cache-post-run =
+
+# Always return a 0 (non-error) status code, even if lint errors are found. This
+# is primarily useful in continuous integration scripts.
+# exit-zero =
+
+# A comma-separated list of package or module names from where C extensions may
+# be loaded. Extensions are loading into the active Python interpreter and may
+# run arbitrary code.
+# extension-pkg-allow-list =
+
+# A comma-separated list of package or module names from where C extensions may
+# be loaded. Extensions are loading into the active Python interpreter and may
+# run arbitrary code. (This is an alternative name to extension-pkg-allow-list
+# for backward compatibility.)
+# extension-pkg-whitelist =
+
+# Return non-zero exit code if any of these messages/categories are detected,
+# even if score is above --fail-under value. Syntax same as enable. Messages
+# specified are enabled, while categories only check already-enabled messages.
+# fail-on =
+
+# Specify a score threshold under which the program will exit with error.
+fail-under = 10
+
+# Interpret the stdin as a python script, whose filename needs to be passed as
+# the module_or_package argument.
+# from-stdin =
+
+# Files or directories to be skipped. They should be base names, not paths.
+ignore = ["CVS"]
+
+# Add files or directories matching the regular expressions patterns to the
+# ignore-list. The regex matches against paths and can be in Posix or Windows
+# format. Because '\\' represents the directory delimiter on Windows systems, it
+# can't be used as an escape character.
+# ignore-paths =
+
+# Files or directories matching the regular expression patterns are skipped. The
+# regex matches against base names, not paths. The default value ignores Emacs
+# file locks
+ignore-patterns = ["^\\.#"]
+
+# List of module names for which member attributes should not be checked and will
+# not be imported (useful for modules/projects where namespaces are manipulated
+# during runtime and thus existing member attributes cannot be deduced by static
+# analysis). It supports qualified module names, as well as Unix pattern
+# matching.
+# ignored-modules =
+
+# Python code to execute, usually for sys.path manipulation such as
+# pygtk.require().
+# init-hook =
+
+# Use multiple processes to speed up Pylint. Specifying 0 will auto-detect the
+# number of processors available to use, and will cap the count on Windows to
+# avoid hangs.
+jobs = 1
+
+# Control the amount of potential inferred values when inferring a single object.
+# This can help the performance when dealing with large functions or complex,
+# nested conditions.
+limit-inference-results = 100
+
+# List of plugins (as comma separated values of python module names) to load,
+# usually to register additional checkers.
+# load-plugins =
+
+# Pickle collected data for later comparisons.
+persistent = true
+
+# Resolve imports to .pyi stubs if available. May reduce no-member messages and
+# increase not-an-iterable messages.
+# prefer-stubs =
+
+# Minimum Python version to use for version dependent checks. Will default to the
+# version used to run pylint.
+py-version = "3.13"
+
+# Discover python modules and packages in the file system subtree.
+# recursive =
+
+# Add paths to the list of the source roots. Supports globbing patterns. The
+# source root is an absolute path or a path relative to the current working
+# directory used to determine a package namespace for modules located under the
+# source root.
+# source-roots =
+
+# When enabled, pylint would attempt to guess common misconfiguration and emit
+# user-friendly hints instead of false-positive error messages.
+suggestion-mode = true
+
+# Allow loading of arbitrary C extensions. Extensions are imported into the
+# active Python interpreter and may run arbitrary code.
+# unsafe-load-any-extension =
+
+[tool.pylint.basic]
+# Naming style matching correct argument names.
+argument-naming-style = "snake_case"
+
+# Regular expression matching correct argument names. Overrides argument-naming-
+# style. If left empty, argument names will be checked with the set naming style.
+# argument-rgx =
+
+# Naming style matching correct attribute names.
+attr-naming-style = "snake_case"
+
+# Regular expression matching correct attribute names. Overrides attr-naming-
+# style. If left empty, attribute names will be checked with the set naming
+# style.
+# attr-rgx =
+
+# Bad variable names which should always be refused, separated by a comma.
+bad-names = ["foo", "bar", "baz", "toto", "tutu", "tata"]
+
+# Bad variable names regexes, separated by a comma. If names match any regex,
+# they will always be refused
+# bad-names-rgxs =
+
+# Naming style matching correct class attribute names.
+class-attribute-naming-style = "any"
+
+# Regular expression matching correct class attribute names. Overrides class-
+# attribute-naming-style. If left empty, class attribute names will be checked
+# with the set naming style.
+# class-attribute-rgx =
+
+# Naming style matching correct class constant names.
+class-const-naming-style = "UPPER_CASE"
+
+# Regular expression matching correct class constant names. Overrides class-
+# const-naming-style. If left empty, class constant names will be checked with
+# the set naming style.
+# class-const-rgx =
+
+# Naming style matching correct class names.
+class-naming-style = "PascalCase"
+
+# Regular expression matching correct class names. Overrides class-naming-style.
+# If left empty, class names will be checked with the set naming style.
+# class-rgx =
+
+# Naming style matching correct constant names.
+const-naming-style = "UPPER_CASE"
+
+# Regular expression matching correct constant names. Overrides const-naming-
+# style. If left empty, constant names will be checked with the set naming style.
+# const-rgx =
+
+# Minimum line length for functions/classes that require docstrings, shorter ones
+# are exempt.
+docstring-min-length = -1
+
+# Naming style matching correct function names.
+function-naming-style = "snake_case"
+
+# Regular expression matching correct function names. Overrides function-naming-
+# style. If left empty, function names will be checked with the set naming style.
+# function-rgx =
+
+# Good variable names which should always be accepted, separated by a comma.
+good-names = ["i", "j", "k", "ex", "Run", "_"]
+
+# Good variable names regexes, separated by a comma. If names match any regex,
+# they will always be accepted
+# good-names-rgxs =
+
+# Include a hint for the correct naming format with invalid-name.
+# include-naming-hint =
+
+# Naming style matching correct inline iteration names.
+inlinevar-naming-style = "any"
+
+# Regular expression matching correct inline iteration names. Overrides
+# inlinevar-naming-style. If left empty, inline iteration names will be checked
+# with the set naming style.
+# inlinevar-rgx =
+
+# Naming style matching correct method names.
+method-naming-style = "snake_case"
+
+# Regular expression matching correct method names. Overrides method-naming-
+# style. If left empty, method names will be checked with the set naming style.
+# method-rgx =
+
+# Naming style matching correct module names.
+module-naming-style = "snake_case"
+
+# Regular expression matching correct module names. Overrides module-naming-
+# style. If left empty, module names will be checked with the set naming style.
+# module-rgx =
+
+# Colon-delimited sets of names that determine each other's naming style when the
+# name regexes allow several styles.
+# name-group =
+
+# Regular expression which should only match function or class names that do not
+# require a docstring.
+no-docstring-rgx = "^_"
+
+# List of decorators that produce properties, such as abc.abstractproperty. Add
+# to this list to register other decorators that produce valid properties. These
+# decorators are taken in consideration only for invalid-name.
+property-classes = ["abc.abstractproperty"]
+
+# Regular expression matching correct type alias names. If left empty, type alias
+# names will be checked with the set naming style.
+# typealias-rgx =
+
+# Regular expression matching correct type variable names. If left empty, type
+# variable names will be checked with the set naming style.
+# typevar-rgx =
+
+# Naming style matching correct variable names.
+variable-naming-style = "snake_case"
+
+# Regular expression matching correct variable names. Overrides variable-naming-
+# style. If left empty, variable names will be checked with the set naming style.
+# variable-rgx =
+
+[tool.pylint.classes]
+# Warn about protected attribute access inside special methods
+# check-protected-access-in-special-methods =
+
+# List of method names used to declare (i.e. assign) instance attributes.
+defining-attr-methods = ["__init__", "__new__", "setUp", "asyncSetUp", "__post_init__"]
+
+# List of member names, which should be excluded from the protected access
+# warning.
+exclude-protected = ["_asdict", "_fields", "_replace", "_source", "_make", "os._exit"]
+
+# List of valid names for the first argument in a class method.
+valid-classmethod-first-arg = ["cls"]
+
+# List of valid names for the first argument in a metaclass class method.
+valid-metaclass-classmethod-first-arg = ["mcs"]
+
+[tool.pylint.design]
+# List of regular expressions of class ancestor names to ignore when counting
+# public methods (see R0903)
+# exclude-too-few-public-methods =
+
+# List of qualified class names to ignore when counting class parents (see R0901)
+# ignored-parents =
+
+# Maximum number of arguments for function / method.
+max-args = 5
+
+# Maximum number of attributes for a class (see R0902).
+max-attributes = 7
+
+# Maximum number of boolean expressions in an if statement (see R0916).
+max-bool-expr = 5
+
+# Maximum number of branch for function / method body.
+# Why????????????????????????????????
+max-branches = 1200
+
+# Maximum number of locals for function / method body.
+max-locals = 15
+
+# Maximum number of parents for a class (see R0901).
+max-parents = 7
+
+# Maximum number of positional arguments for function / method.
+max-positional-arguments = 5
+
+# Maximum number of public methods for a class (see R0904).
+max-public-methods = 20
+
+# Maximum number of return / yield for function / method body.
+max-returns = 6
+
+# Maximum number of statements in function / method body.
+max-statements = 50
+
+# Minimum number of public methods for a class (see R0903).
+min-public-methods = 2
+
+[tool.pylint.exceptions]
+# Exceptions that will emit a warning when caught.
+overgeneral-exceptions = ["builtins.BaseException", "builtins.Exception"]
+
+[tool.pylint.format]
+# Expected format of line ending, e.g. empty (any line ending), LF or CRLF.
+# expected-line-ending-format =
+
+# Regexp for a line that is allowed to be longer than the limit.
+ignore-long-lines = "^\\s*(# )?<?https?://\\S+>?$"
+
+# Number of spaces of indent required inside a hanging or continued line.
+indent-after-paren = 4
+
+# String used as indentation unit. This is usually "    " (4 spaces) or "\t" (1
+# tab).
+indent-string = "\t"
+
+# Maximum number of characters on a single line.
+max-line-length = 100
+
+# Maximum number of lines in a module.
+max-module-lines = 1000
+
+# Allow the body of a class to be on the same line as the declaration if body
+# contains single statement.
+# single-line-class-stmt =
+
+# Allow the body of an if to be on the same line as the test if there is no else.
+# single-line-if-stmt =
+
+[tool.pylint.imports]
+# List of modules that can be imported at any level, not just the top level one.
+# allow-any-import-level =
+
+# Allow explicit reexports by alias from a package __init__.
+# allow-reexport-from-package =
+
+# Allow wildcard imports from modules that define __all__.
+# allow-wildcard-with-all =
+
+# Deprecated modules which should not be used, separated by a comma.
+# deprecated-modules =
+
+# Output a graph (.gv or any supported image format) of external dependencies to
+# the given file (report RP0402 must not be disabled).
+# ext-import-graph =
+
+# Output a graph (.gv or any supported image format) of all (i.e. internal and
+# external) dependencies to the given file (report RP0402 must not be disabled).
+# import-graph =
+
+# Output a graph (.gv or any supported image format) of internal dependencies to
+# the given file (report RP0402 must not be disabled).
+# int-import-graph =
+
+# Force import order to recognize a module as part of the standard compatibility
+# libraries.
+# known-standard-library =
+
+# Force import order to recognize a module as part of a third party library.
+known-third-party = ["enchant"]
+
+# Couples of modules and preferred modules, separated by a comma.
+# preferred-modules =
+
+[tool.pylint.logging]
+# The type of string formatting that logging methods do. `old` means using %
+# formatting, `new` is for `{}` formatting.
+logging-format-style = "old"
+
+# Logging modules to check that the string format arguments are in logging
+# function parameter format.
+logging-modules = ["logging"]
+
+[tool.pylint."messages control"]
+# Only show warnings with the listed confidence levels. Leave empty to show all.
+# Valid levels: HIGH, CONTROL_FLOW, INFERENCE, INFERENCE_FAILURE, UNDEFINED.
+confidence = ["HIGH", "CONTROL_FLOW", "INFERENCE", "INFERENCE_FAILURE", "UNDEFINED"]
+
+# Disable the message, report, category or checker with the given id(s). You can
+# either give multiple identifiers separated by comma (,) or put this option
+# multiple times (only on the command line, not in the configuration file where
+# it should appear only once). You can also use "--disable=all" to disable
+# everything first and then re-enable specific checks. For example, if you want
+# to run only the similarities checker, you can use "--disable=all
+# --enable=similarities". If you want to run only the classes checker, but have
+# no Warning level messages displayed, use "--disable=all --enable=classes
+# --disable=W".
+disable = ["raw-checker-failed", "bad-inline-option", "locally-disabled", "file-ignored", "suppressed-message", "useless-suppression", "deprecated-pragma", "use-implicit-booleaness-not-comparison-to-string", "use-implicit-booleaness-not-comparison-to-zero", "use-symbolic-message-instead"]
+
+# Enable the message, report, category or checker with the given id(s). You can
+# either give multiple identifier separated by comma (,) or put this option
+# multiple time (only on the command line, not in the configuration file where it
+# should appear only once). See also the "--disable" option for examples.
+# enable =
+
+[tool.pylint.method_args]
+# List of qualified names (i.e., library.method) which require a timeout
+# parameter e.g. 'requests.api.get,requests.api.post'
+timeout-methods = ["requests.api.delete", "requests.api.get", "requests.api.head", "requests.api.options", "requests.api.patch", "requests.api.post", "requests.api.put", "requests.api.request"]
+
+[tool.pylint.miscellaneous]
+# List of note tags to take in consideration, separated by a comma.
+notes = ["FIXME", "XXX", "TODO"]
+
+# Regular expression of note tags to take in consideration.
+# notes-rgx =
+
+[tool.pylint.refactoring]
+# Maximum number of nested blocks for function / method body
+max-nested-blocks = 5
+
+# Complete name of functions that never returns. When checking for inconsistent-
+# return-statements if a never returning function is called then it will be
+# considered as an explicit return statement and no message will be printed.
+never-returning-functions = ["sys.exit", "argparse.parse_error"]
+
+# Let 'consider-using-join' be raised when the separator to join on would be non-
+# empty (resulting in expected fixes of the type: ``"- " + " - ".join(items)``)
+suggest-join-with-non-empty-separator = true
+
+[tool.pylint.reports]
+# Python expression which should return a score less than or equal to 10. You
+# have access to the variables 'fatal', 'error', 'warning', 'refactor',
+# 'convention', and 'info' which contain the number of messages in each category,
+# as well as 'statement' which is the total number of statements analyzed. This
+# score is used by the global evaluation report (RP0004).
+evaluation = "max(0, 0 if fatal else 10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10))"
+
+# Template used to display messages. This is a python new-style format string
+# used to format the message information. See doc for all details.
+# msg-template =
+
+# Set the output format. Available formats are: text, parseable, colorized, json2
+# (improved json format), json (old json format) and msvs (visual studio). You
+# can also give a reporter class, e.g. mypackage.mymodule.MyReporterClass.
+# output-format =
+
+# Tells whether to display a full report or only the messages.
+# reports =
+
+# Activate the evaluation score.
+score = true
+
+[tool.pylint.similarities]
+# Comments are removed from the similarity computation
+ignore-comments = true
+
+# Docstrings are removed from the similarity computation
+ignore-docstrings = true
+
+# Imports are removed from the similarity computation
+ignore-imports = true
+
+# Signatures are removed from the similarity computation
+ignore-signatures = true
+
+# Minimum lines number of a similarity.
+min-similarity-lines = 4
+
+[tool.pylint.spelling]
+# Limits count of emitted suggestions for spelling mistakes.
+max-spelling-suggestions = 4
+
+# Spelling dictionary name. No available dictionaries : You need to install both
+# the python package and the system dependency for enchant to work.
+# spelling-dict =
+
+# List of comma separated words that should be considered directives if they
+# appear at the beginning of a comment and should not be checked.
+spelling-ignore-comment-directives = "fmt: on,fmt: off,noqa:,noqa,nosec,isort:skip,mypy:"
+
+# List of comma separated words that should not be checked.
+# spelling-ignore-words =
+
+# A path to a file that contains the private dictionary; one word per line.
+# spelling-private-dict-file =
+
+# Tells whether to store unknown words to the private dictionary (see the
+# --spelling-private-dict-file option) instead of raising a message.
+# spelling-store-unknown-words =
+
+[tool.pylint.typecheck]
+# List of decorators that produce context managers, such as
+# contextlib.contextmanager. Add to this list to register other decorators that
+# produce valid context managers.
+contextmanager-decorators = ["contextlib.contextmanager"]
+
+# List of members which are set dynamically and missed by pylint inference
+# system, and so shouldn't trigger E1101 when accessed. Python regular
+# expressions are accepted.
+# generated-members =
+
+# Tells whether missing members accessed in mixin class should be ignored. A
+# class is considered mixin if its name matches the mixin-class-rgx option.
+# Tells whether to warn about missing members when the owner of the attribute is
+# inferred to be None.
+ignore-none = true
+
+# This flag controls whether pylint should warn about no-member and similar
+# checks whenever an opaque object is returned when inferring. The inference can
+# return multiple potential results while evaluating a Python object, but some
+# branches might not be evaluated, which results in partial inference. In that
+# case, it might be useful to still emit no-member and other checks for the rest
+# of the inferred objects.
+ignore-on-opaque-inference = true
+
+# List of symbolic message names to ignore for Mixin members.
+ignored-checks-for-mixins = ["no-member", "not-async-context-manager", "not-context-manager", "attribute-defined-outside-init"]
+
+# List of class names for which member attributes should not be checked (useful
+# for classes with dynamically set attributes). This supports the use of
+# qualified names.
+ignored-classes = ["optparse.Values", "thread._local", "_thread._local", "argparse.Namespace"]
+
+# Show a hint with possible names when a member name was not found. The aspect of
+# finding the hint is based on edit distance.
+missing-member-hint = true
+
+# The minimum edit distance a name should have in order to be considered a
+# similar match for a missing member name.
+missing-member-hint-distance = 1
+
+# The total number of similar names that should be taken in consideration when
+# showing a hint for a missing member.
+missing-member-max-choices = 1
+
+# Regex pattern to define which classes are considered mixins.
+mixin-class-rgx = ".*[Mm]ixin"
+
+# List of decorators that change the signature of a decorated function.
+# signature-mutators =
+
+[tool.pylint.variables]
+# List of additional names supposed to be defined in builtins. Remember that you
+# should avoid defining new builtins when possible.
+# additional-builtins =
+
+# Tells whether unused global variables should be treated as a violation.
+allow-global-unused-variables = true
+
+# List of names allowed to shadow builtins
+# allowed-redefined-builtins =
+
+# List of strings which can identify a callback function by name. A callback name
+# must start or end with one of those strings.
+callbacks = ["cb_", "_cb"]
+
+# A regular expression matching the name of dummy variables (i.e. expected to not
+# be used).
+dummy-variables-rgx = "_+$|(_[a-zA-Z0-9_]*[a-zA-Z0-9]+?$)|dummy|^ignored_|^unused_"
+
+# Argument names that match this expression will be ignored.
+ignored-argument-names = "_.*|^ignored_|^unused_"
+
+# Tells whether we should check for unused import in __init__ files.
+# init-import =
+
+# List of qualified module names which can have objects that can redefine
+# builtins.
+redefining-builtins-modules = ["six.moves", "past.builtins", "future.builtins", "builtins", "io"]
+
+
diff --git a/simpleddns.py b/simpleddns.py
index 19196ce..9434be6 100755
--- a/simpleddns.py
+++ b/simpleddns.py
@@ -1,10 +1,26 @@
 #!/usr/bin/env python3
+'''Simple Dynamic DNS updater'''
+
 import os
 import sys
-import requests
-import stat
 import subprocess
+import argparse
+import ast
+from abc import ABC, abstractmethod
+from typing import NoReturn, Optional
 from pathlib import Path
+# import requests
+
+def parse_args() -> argparse.Namespace:
+	'''Parse command-line arguments'''
+	parser = argparse.ArgumentParser(prog='simpleddns',
+		description='Simple dynamic DNS updater',
+		epilog='''ENVIRONMENT VARIABLES
+	SIMPLEDDNS_CONFIG_DIR - directory where configburation files are stored''')
+	parser.add_argument('--setup', help='Set up configuration', action='store_true')
+	return parser.parse_args()
+
+args = parse_args()
 
 simpleddns_config_dir = os.getenv('SIMPLEDDNS_CONFIG_DIR')
 xdg_config_dir = os.getenv('XDG_CONFIG_DIR')
@@ -15,27 +31,139 @@ elif xdg_config_dir:
 else:
 	config_dir = Path('~/.config/simpleddns').expanduser()
 os.makedirs(config_dir, exist_ok = True)
+config_path = Path(config_dir, 'config')
 
-def fatal_error(message):
+def fatal_error(message: str) -> NoReturn:
+	'''Output error message & exit'''
 	sys.stderr.write(f'Fatal error: {message}\n')
-	exit(1)
+	sys.exit(1)
+
+def setup_config() -> None:
+	'''Interactively set up configuration file'''
+	if config_path.exists():
+		should_delete = input('Configuration already exists. Delete it [y/n]? ')
+		if not should_delete.strip().lower().startswith('y'):
+			print('Aborting.')
+			return
+		config_path.unlink()
+	default_get_ip = 'curl --no-progress-meter ifconfig.co'
+	get_ip = input(f'Command for getting IP address [default: {default_get_ip}]? ').strip()
+	if not get_ip:
+		get_ip = default_get_ip
+	domain_name = input('Domain name? ').strip()
+	if not domain_name:
+		fatal_error('Domain name must be set')
+	if any(c.isspace() for c in domain_name):
+		fatal_error('Domain name must not contain any whitespace')
+	print('1. Linode Domains')
+	# TODO: AWS
+	domain_type = input('Select a domain type from the list above [1-1]: ').strip()
+	if domain_type == '1':
+		access_token = input('Enter personal access token: ')
+		options = f'access_token = {repr(access_token)}'
+		type_name = 'linode'
+	else:
+		print('Invalid choice')
+		return
+	fd = os.open(config_path, os.O_CREAT | os.O_WRONLY | os.O_EXCL, 0o600)
+	with os.fdopen(fd, 'w') as config:
+		config.write(f'''Domain {type_name} {domain_name}
+    getip = {repr(get_ip)}
+    {options}
+''')
+if args.setup:
+	setup_config()
+	sys.exit(0)
 
-get_ip_path = Path(config_dir, 'getip')
+if not config_path.exists():
+	fatal_error("Configuration doesn't exist. Try running with --setup first.")
+if os.name == 'posix':
+	config_mode = config_path.stat().st_mode
+	if config_mode & 0o4:
+		fatal_error(f'''DANGER: configuration file {config_path} allows
+reading by other users (mode {config_mode}).
+If there are API tokens in there, revoke them immediately!!''')
 
-if not get_ip_path.exists():
-	print(f'Warning: {get_ip_path} does not exist. Putting default of "curl ifconfig.co" there')
-	with open(get_ip_path, 'w') as f:
-		f.write('curl --no-progress-meter ifconfig.co')
+class Domain(ABC):
+	'''A domain whose DNS will be updated'''
+	domain: str
+	getip: str
+	def __init__(self, domain: str):
+		self.domain = domain
+	@abstractmethod
+	def update(self, ip: str) -> None:
+		'''Make necessary API request to update domain to use new IP address'''
+	@abstractmethod
+	def validate_specifics(self) -> str:
+		'''Validate details specific to subclass'''
+	def validate(self) -> str:
+		'''Validate this object (ensure all required fields are set)'''
+		if not getattr(self, 'getip', ''):
+			return 'getip not set'
+		return self.validate_specifics()
+	def get_ip(self) -> Optional[str]:
+		'''Get IP address using the registered command.'''
+		result = subprocess.run(self.getip, shell=True, stdout=subprocess.PIPE, check=False)
+		if result.returncode:
+			print(f'WARNING: {self.getip} failed (exit code {result.returncode})')
+			return None
+		return result.stdout.decode(errors='replace').strip()
 
-def get_ip():
-	if os.name == 'posix' and (get_ip_path.stat().st_mode & 0o100):
-		command = str(get_ip_path)
-	else:
-		command = open(get_ip_path).read()
-	result = subprocess.run(command, shell=True, stdout=subprocess.PIPE)
-	if result.returncode:
-		print(f'WARNING: {command} failed (exit code {result.returncode})')
-		return None
-	return result.stdout.decode(errors='replace').strip()
-
-print(get_ip())
+class LinodeDomain(Domain):
+	'''Domain registered with Linode Domains'''
+	access_token: str
+	def __repr__(self) -> str:
+		return f'<LinodeDomain domain={self.domain} ' \
+			'getip={repr(self.getip)} ' \
+			'access_token={repr(self.access_token)}>'
+	def update(self, ip: str) -> None:
+		print(f'update IP: {ip}')
+	def validate_specifics(self) -> str:
+		if not getattr(self, 'access_token', ''):
+			return 'Access token not set'
+		# OK
+		return ''
+
+def parse_config() -> list[Domain]:
+	'''Parse configuration file'''
+	curr_domain = None
+	domains: list[Domain] = []
+	with open(config_path, encoding='utf-8') as config:
+		for line in config:
+			line = line.strip()
+			if line[0] == '#':
+				# comment
+				continue
+			if line.startswith('Domain '):
+				if curr_domain:
+					domains.append(curr_domain)
+				parts = line.split()
+				if len(parts) != 3:
+					fatal_error('Domain declaration should have exactly ' \
+						'two space-separated arguments (type and name)')
+				kind = parts[1]
+				domain_name = parts[2]
+				if kind == 'linode':
+					curr_domain = LinodeDomain(domain_name)
+				else:
+					fatal_error(f'No such domain type: {kind}')
+			else:
+				if not curr_domain:
+					fatal_error('First non-empty line of configuration must be a Domain declaration')
+				parts = [part.strip() for part in line.split('=', maxsplit=1)]
+				if len(parts) != 2:
+					fatal_error(f'Invalid syntax (want key = value): {line}')
+				[key, value] = parts
+				setattr(curr_domain, key, ast.literal_eval(value))
+	if curr_domain:
+		domains.append(curr_domain)
+	for domain in domains:
+		err = domain.validate()
+		if err:
+			fatal_error(f'In domain {domain.domain}: {err}')
+	return domains
+
+configured_domains = parse_config()
+if not configured_domains:
+	fatal_error('No domains defined. Try running with --setup?')
+print(configured_domains[0].get_ip())