gps303/lookaside.py

   1 """ Estimate coordinates from WIFI_POSITIONING and send back """
   2
   3 from configparser import ConfigParser
   4 from datetime import datetime, timezone
   5 from importlib import import_module
   6 from logging import getLogger
   7 from os import umask
   8 from struct import pack
   9 import zmq
  10
  11 from . import common
  12 from .gps303proto import parse_message, proto_name, WIFI_POSITIONING
  13 from .zmsg import Bcast, Resp, topic
  14
  15 log = getLogger("gps303/lookaside")
  16
  17
  18 def runserver(conf: ConfigParser) -> None:
  19     qry = import_module("." + conf.get("lookaside", "backend"), __package__)
  20     qry.init(conf)
  21     # Is this https://github.com/zeromq/pyzmq/issues/1627 still not fixed?!
  22     zctx = zmq.Context()  # type: ignore
  23     zsub = zctx.socket(zmq.SUB)  # type: ignore
  24     zsub.connect(conf.get("collector", "publishurl"))
  25     zsub.setsockopt(zmq.SUBSCRIBE, topic(proto_name(WIFI_POSITIONING)))
  26     zpush = zctx.socket(zmq.PUSH)  # type: ignore
  27     zpush.connect(conf.get("collector", "listenurl"))
  28
  29     try:
  30         while True:
  31             zmsg = Bcast(zsub.recv())
  32             msg = parse_message(zmsg.packet)
  33             log.debug(
  34                 "IMEI %s from %s at %s: %s",
  35                 zmsg.imei,
  36                 zmsg.peeraddr,
  37                 datetime.fromtimestamp(zmsg.when).astimezone(tz=timezone.utc),
  38                 msg,
  39             )
  40             try:
  41                 lat, lon = qry.lookup(
  42                     msg.mcc, msg.mnc, msg.gsm_cells, msg.wifi_aps
  43                 )
  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             except Exception as e:
  52                 log.warning("Lookup for %s resulted in %s", msg, e)
  53
  54     except KeyboardInterrupt:
  55         zsub.close()
  56         zpush.close()
  57         zctx.destroy()  # type: ignore
  58         qry.shut()
  59
  60
  61 if __name__.endswith("__main__"):
  62     runserver(common.init(log))