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     if conf.get("lookaside", "backend") == "opencellid":
  19         qry = import_module(".opencellid", __package__)
  20     else:
  21         raise NotImplementedError(
  22             "Lookaside only implements opencellid backend"
  23         )
  24     qry.init(conf)
  25     zctx = zmq.Context()
  26     zsub = zctx.socket(zmq.SUB)
  27     zsub.connect(conf.get("collector", "publishurl"))
  28     zsub.setsockopt(zmq.SUBSCRIBE, topic(WIFI_POSITIONING.PROTO))
  29     zpush = zctx.socket(zmq.PUSH)
  30     zpush.connect(conf.get("collector", "listenurl"))
  31
  32     try:
  33         while True:
  34             zmsg = Bcast(zsub.recv())
  35             msg = parse_message(zmsg.packet)
  36             log.debug(
  37                 "IMEI %s from %s at %s: %s",
  38                 zmsg.imei,
  39                 zmsg.peeraddr,
  40                 datetime.fromtimestamp(zmsg.when).astimezone(tz=timezone.utc),
  41                 msg,
  42             )
  43             lat, lon = qry.lookup(msg.mcc, msg.gsm_cells, msg.wifi_aps)
  44             resp = Resp(
  45                 imei=zmsg.imei,
  46                 when=zmsg.when,  # not the current time, but the original!
  47                 packet=msg.Out(latitude=lat, longitude=lon).packed,
  48             )
  49             log.debug("Response for lat=%s, lon=%s: %s", lat, lon, resp)
  50             zpush.send(resp.packed)
  51
  52     except KeyboardInterrupt:
  53         pass
  54
  55
  56 if __name__.endswith("__main__"):
  57     runserver(common.init(log))