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# -*- coding: utf-8 -*-
# gateways.py
# Copyright (C) 2013-2017 LEAP Encryption Access Project
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Gateway Selection
"""
import copy
import time
def _normalized(label):
return label.lower().replace(',', '_').replace(' ', '_')
class GatewaySelector(object):
# http://www.timeanddate.com/time/map/
equivalent_timezones = {13: -11, 14: -10}
def __init__(self, gateways=None, locations=None, tz_offset=None,
preferred=None):
'''
Constructor for GatewaySelector.
By default, we will use a Time Zone Heuristic to choose the closest
gateway to the user.
If the user specified something in the 'vpn_prefs' section of
bitmaskd.cfg, we will passed a dictionary here with entries for
'countries' and 'locations', in the form of a list. The 'locations'
entry has preference over the 'countries' one.
:param gateways: an unordered list of all the available gateways, read
from the eip-config file.
:type gateways: list
:param locations: a dictionary with the locations, as read from the
eip-config file
:type locations: dict
:param tz_offset: use this offset as a local distance to GMT.
:type tz_offset: int
:param preferred: a dictionary containing the country code (cc) and the
locations (locations) manually preferred by the user.
:type preferred: dict
'''
if gateways is None:
gateways = []
if locations is None:
locations = {}
if preferred is None:
preferred = {}
self.gateways = gateways
self.locations = locations
self.preferred = preferred
self._local_offset = tz_offset
if tz_offset is None:
tz_offset = self._get_local_offset()
if tz_offset in self.equivalent_timezones:
tz_offset = self.equivalent_timezones[tz_offset]
self._local_offset = tz_offset
def select_gateways(self):
"""
Returns the IPs top 4 preferred gateways, in order.
"""
gateways = [gateway['ip_address']
for gateway in self.get_sorted_gateways()][:4]
return gateways
def get_sorted_gateways(self):
"""
Returns a tuple with location-label, IP and Country Code with all the
available gateways, sorted by order of preference.
"""
gateways_timezones = []
locations = self.locations
for idx, gateway in enumerate(self.gateways):
distance = 99 # if hasn't location -> should go last
location = locations.get(gateway.get('location'))
gateway = gateway.copy()
if location is not None:
gateway.update(location)
timezone = location.get('timezone')
if timezone is not None:
offset = int(timezone)
if offset in self.equivalent_timezones:
offset = self.equivalent_timezones[offset]
distance = self._get_timezone_distance(offset)
gateway['distance'] = distance
gateways_timezones.append(gateway)
gateways_timezones = sorted(gateways_timezones,
key=lambda gw: gw['distance'])
return self.apply_user_preferences(gateways_timezones)
def apply_user_preferences(self, options):
"""
We re-sort the pre-sorted list of gateway options, according with the
user's preferences.
Location has preference over the Country Code indication.
"""
applied = []
presorted = copy.copy(options)
for location in self.preferred.get('loc', []):
for index, gw in enumerate(presorted):
if ('location' in gw and
_normalized(gw['location']) == _normalized(location)):
applied.append(gw)
presorted.pop(index)
for cc in self.preferred.get('cc', []):
for index, gw in enumerate(presorted):
if ('country_code' in gw and
_normalized(gw['country_code']) == _normalized(cc)):
applied.append(gw)
presorted.pop(index)
if presorted:
applied += presorted
return applied
def get_gateways_country_code(self):
country_codes = {}
locations = self.locations
if not locations:
return
gateways = self.gateways
for idx, gateway in enumerate(gateways):
gateway_location = gateway.get('location')
ip = self._eipconfig.get_gateway_ip(idx)
if gateway_location is not None:
ccode = locations[gateway['location']]['country_code']
country_codes[ip] = ccode
return country_codes
def _get_timezone_distance(self, offset):
'''
Return the distance between the local timezone and
the one with offset 'offset'.
:param offset: the distance of a timezone to GMT.
:type offset: int
:returns: distance between local offset and param offset.
:rtype: int
'''
timezones = range(-11, 13)
tz1 = offset
tz2 = self._local_offset
distance = abs(timezones.index(tz1) - timezones.index(tz2))
if distance > 12:
if tz1 < 0:
distance = timezones.index(tz1) + timezones[::-1].index(tz2)
else:
distance = timezones[::-1].index(tz1) + timezones.index(tz2)
return distance
def _get_local_offset(self):
'''
Return the distance between GMT and the local timezone.
:rtype: int
'''
local_offset = time.timezone
if time.daylight:
local_offset = time.altzone
return -local_offset / 3600
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