[feature] automatic vpn gateway selection, based on timezone

This is a first approach to automatic gateways selection.
More things are missing:

- allow manual selection, by location or country code.
- take the hemisphere into account.
- expose the selected gw to the api/cli

but overall seems this is a good approach to make 0.10 release usable in
terms of vpn.

- Resolves: #8804

1 files changed, 143 insertions, 0 deletions

diff --git a/src/leap/bitmask/vpn/gateways.py b/src/leap/bitmask/vpn/gateways.py
new file mode 100644
index 0000000..950e37c
--- /dev/null
+++ b/src/leap/bitmask/vpn/gateways.py
@@ -0,0 +1,143 @@
+# -*- 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 logging
+import os
+import re
+import time
+
+from leap.common.config import get_path_prefix
+
+
+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):
+        '''
+        Constructor for GatewaySelector.
+
+        :param tz_offset: use this offset as a local distance to GMT.
+        :type tz_offset: int
+        '''
+        if gateways is None:
+            gateways = []
+        if locations is None:
+            locations = {}
+        self.gateways = gateways
+        self.locations = locations
+        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[1] 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'))
+
+            label = gateway.get('location', 'Unknown')
+            country = 'XX'
+            if location is not None:
+                country = location.get('country_code', 'XX')
+                label = location.get('name', label)
+                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)
+            ip = self.gateways[idx].get('ip_address')
+            gateways_timezones.append((ip, distance, label, country))
+
+        gateways_timezones = sorted(gateways_timezones, key=lambda gw: gw[1])
+
+        result = []
+        for ip, distance, label, country in gateways_timezones:
+            result.append((label, ip, country))
+        return result
+
+    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