gps303/lookaside.py

   1 """ Estimate coordinates from WIFI_POSITIONING and send back """
   2
   3 from datetime import datetime, timezone
   4 from logging import getLogger
   5 from struct import pack
   6 import zmq
   7
   8 from . import common
   9 from .gps303proto import parse_message, proto_by_name, WIFI_POSITIONING
  10 from .opencellid import qry_cell
  11 from .zmsg import Bcast, Resp
  12
  13 log = getLogger("gps303/lookaside")
  14
  15
  16 def runserver(conf):
  17     zctx = zmq.Context()
  18     zsub = zctx.socket(zmq.SUB)
  19     zsub.connect(conf.get("collector", "publishurl"))
  20     topic = pack("B", proto_by_name("WIFI_POSITIONING"))
  21     zsub.setsockopt(zmq.SUBSCRIBE, topic)
  22     zpush = zctx.socket(zmq.PUSH)
  23     zpush.connect(conf.get("collector", "listenurl"))
  24
  25     try:
  26         while True:
  27             zmsg = Bcast(zsub.recv())
  28             msg = parse_message(zmsg.packet)
  29             log.debug(
  30                 "IMEI %s from %s at %s: %s",
  31                 zmsg.imei,
  32                 zmsg.peeraddr,
  33                 datetime.fromtimestamp(zmsg.when).astimezone(tz=timezone.utc),
  34                 msg,
  35             )
  36             if not isinstance(msg, WIFI_POSITIONING):
  37                 log.error(
  38                     "IMEI %s from %s at %s: %s",
  39                     zmsg.imei,
  40                     zmsg.peeraddr,
  41                     datetime.fromtimestamp(zmsg.when).astimezone(
  42                         tz=timezone.utc
  43                     ),
  44                     msg,
  45                 )
  46                 continue
  47             lat, lon = qry_cell(
  48                 conf["opencellid"]["dbfn"], msg.mcc, msg.gsm_cells
  49             )
  50             resp = Resp(imei=zmsg.imei, packet=msg.Out(lat=lat, lon=lon).packed)
  51             log.debug("Response for lat=%s, lon=%s: %s", lat, lon, resp)
  52             zpush.send(resp.packed)
  53
  54     except KeyboardInterrupt:
  55         pass
  56
  57
  58 if __name__.endswith("__main__"):
  59     runserver(common.init(log))