detection_rules/misc.py

# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
# or more contributor license agreements. Licensed under the Elastic License
# 2.0; you may not use this file except in compliance with the Elastic License
# 2.0.

"""Misc support."""
import os
import re
import time
import unittest
import uuid
from pathlib import Path
from functools import wraps
from typing import NoReturn, Optional

import click
import requests

from kibana import Kibana

from .utils import add_params, cached, get_path, load_etc_dump

_CONFIG = {}

LICENSE_HEADER = """
Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
or more contributor license agreements. Licensed under the Elastic License
2.0; you may not use this file except in compliance with the Elastic License
2.0.
""".strip()

LICENSE_LINES = LICENSE_HEADER.splitlines()
PYTHON_LICENSE = "\n".join("# " + line for line in LICENSE_LINES)
JS_LICENSE = """
/*
{}
 */
""".strip().format("\n".join(' * ' + line for line in LICENSE_LINES))


ROOT_DIR = Path(__file__).parent.parent


class ClientError(click.ClickException):
    """Custom CLI error to format output or full debug stacktrace."""

    def __init__(self, message, original_error=None):
        super(ClientError, self).__init__(message)
        self.original_error = original_error
        self.original_error_type = type(original_error).__name__ if original_error else ''

    def show(self, file=None, err=True):
        """Print the error to the console."""
        # err_msg = f' {self.original_error_type}' if self.original_error else ''
        msg = f'{click.style(f"CLI Error ({self.original_error_type})", fg="red", bold=True)}: {self.format_message()}'
        click.echo(msg, err=err, file=file)


def client_error(message, exc: Exception = None, debug=None, ctx: click.Context = None, file=None,
                 err=None) -> NoReturn:
    config_debug = True if ctx and ctx.ensure_object(dict) and ctx.obj.get('debug') is True else False
    debug = debug if debug is not None else config_debug

    if debug:
        click.echo(click.style('DEBUG: ', fg='yellow') + message, err=err, file=file)
        raise
    else:
        raise ClientError(message, original_error=exc)


def nested_get(_dict, dot_key, default=None):
    """Get a nested field from a nested dict with dot notation."""
    if _dict is None or dot_key is None:
        return default
    elif '.' in dot_key and isinstance(_dict, dict):
        dot_key = dot_key.split('.')
        this_key = dot_key.pop(0)
        return nested_get(_dict.get(this_key, default), '.'.join(dot_key), default)
    else:
        return _dict.get(dot_key, default)


def nested_set(_dict, dot_key, value):
    """Set a nested field from a key in dot notation."""
    keys = dot_key.split('.')
    for key in keys[:-1]:
        _dict = _dict.setdefault(key, {})

    if isinstance(_dict, dict):
        _dict[keys[-1]] = value
    else:
        raise ValueError('dict cannot set a value to a non-dict for {}'.format(dot_key))


def nest_from_dot(dots, value):
    """Nest a dotted field and set the innermost value."""
    fields = dots.split('.')

    if not fields:
        return {}

    nested = {fields.pop(): value}

    for field_ in reversed(fields):
        nested = {field_: nested}

    return nested


def schema_prompt(name, value=None, is_required=False, **options):
    """Interactively prompt based on schema requirements."""
    name = str(name)
    field_type = options.get('type')
    pattern = options.get('pattern')
    enum = options.get('enum', [])
    minimum = options.get('minimum')
    maximum = options.get('maximum')
    min_item = options.get('min_items', 0)
    max_items = options.get('max_items', 9999)

    default = options.get('default')
    if default is not None and str(default).lower() in ('true', 'false'):
        default = str(default).lower()

    if 'date' in name:
        default = time.strftime('%Y/%m/%d')

    if name == 'rule_id':
        default = str(uuid.uuid4())

    if len(enum) == 1 and is_required and field_type != "array":
        return enum[0]

    def _check_type(_val):
        if field_type in ('number', 'integer') and not str(_val).isdigit():
            print('Number expected but got: {}'.format(_val))
            return False
        if pattern and (not re.match(pattern, _val) or len(re.match(pattern, _val).group(0)) != len(_val)):
            print('{} did not match pattern: {}!'.format(_val, pattern))
            return False
        if enum and _val not in enum:
            print('{} not in valid options: {}'.format(_val, ', '.join(enum)))
            return False
        if minimum and (type(_val) is int and int(_val) < minimum):
            print('{} is less than the minimum: {}'.format(str(_val), str(minimum)))
            return False
        if maximum and (type(_val) is int and int(_val) > maximum):
            print('{} is greater than the maximum: {}'.format(str(_val), str(maximum)))
            return False
        if field_type == 'boolean' and _val.lower() not in ('true', 'false'):
            print('Boolean expected but got: {}'.format(str(_val)))
            return False
        return True

    def _convert_type(_val):
        if field_type == 'boolean' and not type(_val) is bool:
            _val = True if _val.lower() == 'true' else False
        return int(_val) if field_type in ('number', 'integer') else _val

    prompt = '{name}{default}{required}{multi}'.format(
        name=name,
        default=' [{}] ("n/a" to leave blank) '.format(default) if default else '',
        required=' (required) ' if is_required else '',
        multi=' (multi, comma separated) ' if field_type == 'array' else '').strip() + ': '

    while True:
        result = value or input(prompt) or default
        if result == 'n/a':
            result = None

        if not result:
            if is_required:
                value = None
                continue
            else:
                return

        if field_type == 'array':
            result_list = result.split(',')

            if not (min_item < len(result_list) < max_items):
                if is_required:
                    value = None
                    break
                else:
                    return []

            for value in result_list:
                if not _check_type(value):
                    if is_required:
                        value = None
                        break
                    else:
                        return []
            if is_required and value is None:
                continue
            else:
                return [_convert_type(r) for r in result_list]
        else:
            if _check_type(result):
                return _convert_type(result)
            elif is_required:
                value = None
                continue
            return


def get_kibana_rules_map(repo='elastic/kibana', branch='master'):
    """Get list of available rules from the Kibana repo and return a list of URLs."""
    # ensure branch exists
    r = requests.get(f'https://api.github.com/repos/{repo}/branches/{branch}')
    r.raise_for_status()

    url = ('https://api.github.com/repos/{repo}/contents/x-pack/{legacy}plugins/{app}/server/lib/'
           'detection_engine/rules/prepackaged_rules?ref={branch}')

    gh_rules = requests.get(url.format(legacy='', app='security_solution', branch=branch, repo=repo)).json()

    # pre-7.9 app was siem
    if isinstance(gh_rules, dict) and gh_rules.get('message', '') == 'Not Found':
        gh_rules = requests.get(url.format(legacy='', app='siem', branch=branch, repo=repo)).json()

    # pre-7.8 the siem was under the legacy directory
    if isinstance(gh_rules, dict) and gh_rules.get('message', '') == 'Not Found':
        gh_rules = requests.get(url.format(legacy='legacy/', app='siem', branch=branch, repo=repo)).json()

    if isinstance(gh_rules, dict) and gh_rules.get('message', '') == 'Not Found':
        raise ValueError(f'rules directory does not exist for {repo} branch: {branch}')

    return {os.path.splitext(r['name'])[0]: r['download_url'] for r in gh_rules if r['name'].endswith('.json')}


def get_kibana_rules(*rule_paths, repo='elastic/kibana', branch='master', verbose=True, threads=50):
    """Retrieve prepackaged rules from kibana repo."""
    from multiprocessing.pool import ThreadPool

    kibana_rules = {}

    if verbose:
        thread_use = f' using {threads} threads' if threads > 1 else ''
        click.echo(f'Downloading rules from {repo} {branch} branch in kibana repo{thread_use} ...')

    rule_paths = [os.path.splitext(os.path.basename(p))[0] for p in rule_paths]
    rules_mapping = [(n, u) for n, u in get_kibana_rules_map(repo=repo, branch=branch).items() if n in rule_paths] \
        if rule_paths else get_kibana_rules_map(repo=repo, branch=branch).items()

    def download_worker(rule_info):
        n, u = rule_info
        kibana_rules[n] = requests.get(u).json()

    pool = ThreadPool(processes=threads)
    pool.map(download_worker, rules_mapping)
    pool.close()
    pool.join()

    return kibana_rules


@cached
def load_current_package_version() -> str:
    """Load the current package version from config file."""
    return load_etc_dump('packages.yaml')['package']['name']


def get_default_config() -> Optional[Path]:
    return next(get_path().glob('.detection-rules-cfg.*'), None)


@cached
def parse_user_config():
    """Parse a default config file."""
    import eql

    config_file = get_default_config()
    config = {}

    if config_file and config_file.exists():
        config = eql.utils.load_dump(str(config_file))

        click.secho(f'Loaded config file: {config_file}', fg='yellow')

    return config


def discover_tests(start_dir: str = 'tests', pattern: str = 'test*.py', top_level_dir: Optional[str] = None):
    """Discover all unit tests in a directory."""
    def list_tests(s, tests=None):
        if tests is None:
            tests = []
        for test in s:
            if isinstance(test, unittest.TestSuite):
                list_tests(test, tests)
            else:
                tests.append(test.id())
        return tests

    loader = unittest.defaultTestLoader
    suite = loader.discover(start_dir, pattern=pattern, top_level_dir=top_level_dir or str(ROOT_DIR))
    return list_tests(suite)


def getdefault(name):
    """Callback function for `default` to get an environment variable."""
    envvar = f"DR_{name.upper()}"
    config = parse_user_config()
    return lambda: os.environ.get(envvar, config.get(name))


def get_elasticsearch_client(cloud_id: str = None, elasticsearch_url: str = None, es_user: str = None,
                             es_password: str = None, ctx: click.Context = None, api_key: str = None, **kwargs):
    """Get an authenticated elasticsearch client."""
    from elasticsearch import AuthenticationException, Elasticsearch

    if not (cloud_id or elasticsearch_url):
        client_error("Missing required --cloud-id or --elasticsearch-url")

    # don't prompt for these until there's a cloud id or elasticsearch URL
    basic_auth: (str, str) | None = None
    if not api_key:
        es_user = es_user or click.prompt("es_user")
        es_password = es_password or click.prompt("es_password", hide_input=True)
        basic_auth = (es_user, es_password)

    hosts = [elasticsearch_url] if elasticsearch_url else None
    timeout = kwargs.pop('timeout', 60)
    kwargs['verify_certs'] = not kwargs.pop('ignore_ssl_errors', False)

    try:
        client = Elasticsearch(hosts=hosts, cloud_id=cloud_id, http_auth=basic_auth, timeout=timeout, api_key=api_key,
                               **kwargs)
        # force login to test auth
        client.info()
        return client
    except AuthenticationException as e:
        error_msg = f'Failed authentication for {elasticsearch_url or cloud_id}'
        client_error(error_msg, e, ctx=ctx, err=True)


def get_kibana_client(
    *,
    api_key: str,
    cloud_id: str | None = None,
    kibana_url: str | None = None,
    space: str | None = None,
    ignore_ssl_errors: bool = False,
    **kwargs
):
    """Get an authenticated Kibana client."""
    if not (cloud_id or kibana_url):
        client_error("Missing required --cloud-id or --kibana-url")

    verify = not ignore_ssl_errors
    return Kibana(cloud_id=cloud_id, kibana_url=kibana_url, space=space, verify=verify, api_key=api_key, **kwargs)


client_options = {
    'kibana': {
        'kibana_url': click.Option(['--kibana-url'], default=getdefault('kibana_url')),
        'cloud_id': click.Option(['--cloud-id'], default=getdefault('cloud_id'), help="ID of the cloud instance."),
        'api_key': click.Option(['--api-key'], default=getdefault('api_key')),
        'space': click.Option(['--space'], default=None, help='Kibana space'),
        'ignore_ssl_errors': click.Option(['--ignore-ssl-errors'], default=getdefault('ignore_ssl_errors'))
    },
    'elasticsearch': {
        'cloud_id': click.Option(['--cloud-id'], default=getdefault("cloud_id")),
        'api_key': click.Option(['--api-key'], default=getdefault('api_key')),
        'elasticsearch_url': click.Option(['--elasticsearch-url'], default=getdefault("elasticsearch_url")),
        'es_user': click.Option(['--es-user', '-eu'], default=getdefault("es_user")),
        'es_password': click.Option(['--es-password', '-ep'], default=getdefault("es_password")),
        'timeout': click.Option(['--timeout', '-et'], default=60, help='Timeout for elasticsearch client'),
        'ignore_ssl_errors': click.Option(['--ignore-ssl-errors'], default=getdefault('ignore_ssl_errors'))
    }
}
kibana_options = list(client_options['kibana'].values())
elasticsearch_options = list(client_options['elasticsearch'].values())


def add_client(*client_type, add_to_ctx=True, add_func_arg=True):
    """Wrapper to add authed client."""
    from elasticsearch import Elasticsearch
    from elasticsearch.exceptions import AuthenticationException
    from kibana import Kibana

    def _wrapper(func):
        client_ops_dict = {}
        client_ops_keys = {}
        for c_type in client_type:
            ops = client_options.get(c_type)
            client_ops_dict.update(ops)
            client_ops_keys[c_type] = list(ops)

        if not client_ops_dict:
            raise ValueError(f'Unknown client: {client_type} in {func.__name__}')

        client_ops = list(client_ops_dict.values())

        @wraps(func)
        @add_params(*client_ops)
        def _wrapped(*args, **kwargs):
            ctx: click.Context = next((a for a in args if isinstance(a, click.Context)), None)
            es_client_args = {k: kwargs.pop(k, None) for k in client_ops_keys.get('elasticsearch', [])}
            #                                      shared args like cloud_id
            kibana_client_args = {k: kwargs.pop(k, es_client_args.get(k)) for k in client_ops_keys.get('kibana', [])}

            if 'elasticsearch' in client_type:
                # for nested ctx invocation, no need to re-auth if an existing client is already passed
                elasticsearch_client: Elasticsearch = kwargs.get('elasticsearch_client')
                try:
                    if elasticsearch_client and isinstance(elasticsearch_client, Elasticsearch) and \
                            elasticsearch_client.info():
                        pass
                    else:
                        elasticsearch_client = get_elasticsearch_client(**es_client_args)
                except AuthenticationException:
                    elasticsearch_client = get_elasticsearch_client(**es_client_args)

                if add_func_arg:
                    kwargs['elasticsearch_client'] = elasticsearch_client
                if ctx and add_to_ctx:
                    ctx.obj['es'] = elasticsearch_client

            if 'kibana' in client_type:
                # for nested ctx invocation, no need to re-auth if an existing client is already passed
                kibana_client: Kibana = kwargs.get('kibana_client')
                if kibana_client and isinstance(kibana_client, Kibana):

                    try:
                        with kibana_client:
                            if kibana_client.version:
                                pass  # kibana_client is valid and can be used directly
                    except (requests.HTTPError, AttributeError):
                        kibana_client = get_kibana_client(**kibana_client_args)
                else:
                    # Instantiate a new Kibana client if none was provided or if the provided one is not usable
                    kibana_client = get_kibana_client(**kibana_client_args)

                if add_func_arg:
                    kwargs['kibana_client'] = kibana_client
                if ctx and add_to_ctx:
                    ctx.obj['kibana'] = kibana_client

            return func(*args, **kwargs)

        return _wrapped

    return _wrapper