gps303/lookaside.py

   1 """ Estimate coordinates from WIFI_POSITIONING and send back """
   2
   3 from datetime import datetime, timezone
   4 from importlib import import_module
   5 from logging import getLogger
   6 from os import umask
   7 from struct import pack
   8 import zmq
   9
  10 from . import common
  11 from .gps303proto import parse_message, WIFI_POSITIONING
  12 from .zmsg import Bcast, Resp, topic
  13
  14 log = getLogger("gps303/lookaside")
  15
  16
  17 def runserver(conf):
  18     qry = import_module("." + conf.get("lookaside", "backend"), __package__)
  19     qry.init(conf)
  20     zctx = zmq.Context()
  21     zsub = zctx.socket(zmq.SUB)
  22     zsub.connect(conf.get("collector", "publishurl"))
  23     zsub.setsockopt(zmq.SUBSCRIBE, topic(WIFI_POSITIONING.PROTO))
  24     zpush = zctx.socket(zmq.PUSH)
  25     zpush.connect(conf.get("collector", "listenurl"))
  26
  27     try:
  28         while True:
  29             zmsg = Bcast(zsub.recv())
  30             msg = parse_message(zmsg.packet)
  31             log.debug(
  32                 "IMEI %s from %s at %s: %s",
  33                 zmsg.imei,
  34                 zmsg.peeraddr,
  35                 datetime.fromtimestamp(zmsg.when).astimezone(tz=timezone.utc),
  36                 msg,
  37             )
  38             try:
  39                 lat, lon = qry.lookup(msg.mcc, msg.mnc, msg.gsm_cells, msg.wifi_aps)
  40                 resp = Resp(
  41                     imei=zmsg.imei,
  42                     when=zmsg.when,  # not the current time, but the original!
  43                     packet=msg.Out(latitude=lat, longitude=lon).packed,
  44                 )
  45                 log.debug("Response for lat=%s, lon=%s: %s", lat, lon, resp)
  46                 zpush.send(resp.packed)
  47             except Exception as e:
  48                 log.warning("Lookup for %s resulted in %s", msg, e)
  49
  50     except KeyboardInterrupt:
  51         pass
  52
  53
  54 if __name__.endswith("__main__"):
  55     runserver(common.init(log))