utils.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# utils.py - Common helper methods.
#
# Copyright (c) Addy Yeow <ayeowch@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

"""
Common helper methods.
"""

from gevent import monkey

monkey.patch_all()

import logging
import os
import redis
import requests
import time
from geoip2.database import Reader
from ipaddress import ip_network
from maxminddb.errors import InvalidDatabaseError


class GeoIp(object):
    """
    MaxMind databases.
    """

    def __init__(self):
        # Retry on InvalidDatabaseError due to geoip/update.sh updating
        # *.mmdb that may cause this exception temporarily.
        for i in range(10):
            try:
                self.geoip_city = Reader("geoip/GeoLite2-City.mmdb")
                self.geoip_country = Reader("geoip/GeoLite2-Country.mmdb")
                self.geoip_asn = Reader("geoip/GeoLite2-ASN.mmdb")
            except (InvalidDatabaseError, IOError) as err:
                logging.warning(err)
                time.sleep(0.1)
                continue
            else:
                break

    def city(self, address):
        return self.geoip_city.city(address)

    def country(self, address):
        return self.geoip_country.country(address)

    def asn(self, address):
        return self.geoip_asn.asn(address)


def new_redis_conn(db=0):
    """
    Returns new instance of Redis connection with the right db selected.
    """
    socket = os.environ.get("REDIS_SOCKET", None)
    password = os.environ.get("REDIS_PASSWORD", None)
    return redis.StrictRedis(db=db, password=password, unix_socket_path=socket)


def get_keys(redis_conn, pattern, count=500):
    """
    Returns Redis keys matching pattern by iterating the keys space.
    """
    keys = []
    cursor = 0
    while True:
        (cursor, partial_keys) = redis_conn.scan(cursor, pattern, count)
        keys.extend(partial_keys)
        if cursor == 0:
            break
    return keys


def ip_to_network(address, prefix):
    """
    Returns CIDR notation to represent the address and its prefix.
    """
    network = ip_network(f"{address}/{prefix}", strict=False)
    return f"{network.network_address}/{prefix}"


def http_get(url, timeout=15):
    """
    Returns HTTP response on success and None otherwise.
    """
    try:
        response = requests.get(url, timeout=timeout)
    except requests.exceptions.RequestException as err:
        logging.warning(err)
    else:
        if response.status_code == 200:
            return response
    return None


def http_get_txt(url, timeout=15):
    """
    Returns HTTP text on success and empty string otherwise.
    """
    response = http_get(url, timeout=timeout)
    if response is not None:
        return response.content.decode()
    return ""


def conf_list(conf, section, name):
    """
    Returns list of items for the specified ConfigParser configuration option.
    """
    val = conf.get(section, name).strip()
    if not val:
        return []

    items = set()

    lines = val.split("\n")
    for line in lines:
        line = line.split("#")[0].split(";")[0].strip()
        if line:
            items.add(line)

    return items