gps303/collector.py

   1 """ TCP server that communicates with terminals """
   2
   3 from getopt import getopt
   4 from logging import getLogger, StreamHandler, DEBUG, INFO
   5 from logging.handlers import SysLogHandler
   6 from socket import socket, AF_INET, SOCK_STREAM, SOL_SOCKET, SO_REUSEADDR
   7 from time import time
   8 import sys
   9 import zmq
  10
  11 from .config import readconfig
  12 from .gps303proto import parse_message, HIBERNATION, LOGIN, set_config
  13
  14 CONF = "/etc/gps303.conf"
  15
  16 log = getLogger("gps303/collector")
  17
  18
  19 class Bcast:
  20     """Zmq message to broadcast what was received from the terminal"""
  21     def __init__(self, imei, msg):
  22         self.as_bytes = imei.encode() + msg.to_packet()
  23
  24
  25 class Resp:
  26     """Zmq message received from a third party to send to the terminal"""
  27     def __init__(self, msg):
  28         self.imei = msg[:16].decode()
  29         self.payload = msg[16:]
  30
  31
  32 class Client:
  33     """Connected socket to the terminal plus buffer and metadata"""
  34     def __init__(self, sock, addr):
  35         self.sock = sock
  36         self.addr = addr
  37         self.buffer = b""
  38         self.imei = None
  39
  40     def close(self):
  41         log.debug("Closing fd %d (IMEI %s)", self.sock.fileno(), self.imei)
  42         self.sock.close()
  43         self.buffer = b""
  44         self.imei = None
  45
  46     def recv(self):
  47         """ Read from the socket and parse complete messages """
  48         try:
  49             segment = self.sock.recv(4096)
  50         except OSError:
  51             log.warning("Reading from fd %d (IMEI %s): %s",
  52                     self.sock.fileno(), self.imei, e)
  53             return None
  54         if not segment:  # Terminal has closed connection
  55             log.info("EOF reading from fd %d (IMEI %s)",
  56                     self.sock.fileno(), self.imei)
  57             return None
  58         when = time()
  59         self.buffer += segment
  60         msgs = []
  61         while True:
  62             framestart = self.buffer.find(b"xx")
  63             if framestart == -1:  # No frames, return whatever we have
  64                 break
  65             if framestart > 0:  # Should not happen, report
  66                 log.warning("Undecodable data \"%s\" from fd %d (IMEI %s)",
  67                         self.buffer[:framestart].hex(), self.sock.fileno(), self.imei)
  68                 self.buffer = self.buffer[framestart:]
  69             # At this point, buffer starts with a packet
  70             frameend = self.buffer.find(b"\r\n", 4)
  71             if frameend == -1:  # Incomplete frame, return what we have
  72                 break
  73             msg = parse_message(self.buffer[2:frameend])
  74             self.buffer = self.buffer[frameend+2:]
  75             if isinstance(msg, LOGIN):
  76                 self.imei = msg.imei
  77                 log.info("LOGIN from fd %d: IMEI %s",
  78                         self.sock.fileno(), self.imei)
  79             msgs.append(msg)
  80         return msgs
  81
  82     def send(self, buffer):
  83         try:
  84             self.sock.send(b"xx" + buffer + b"\r\n")
  85         except OSError as e:
  86             log.error("Sending to fd %d (IMEI %s): %s",
  87                     self.sock.fileno, self.imei, e)
  88
  89 class Clients:
  90     def __init__(self):
  91         self.by_fd = {}
  92         self.by_imei = {}
  93
  94     def add(self, clntsock, clntaddr):
  95         fd = clntsock.fileno()
  96         self.by_fd[fd] = Client(clntsock, clntaddr)
  97         return fd
  98
  99     def stop(self, fd):
 100         clnt = self.by_fd[fd]
 101         log.info("Stop serving fd %d (IMEI %s)", clnt.sock.fileno(), clnt.imei)
 102         clnt.close()
 103         if clnt.imei:
 104             del self.by_imei[clnt.imei]
 105         del self.by_fd[fd]
 106
 107     def recv(self, fd):
 108         clnt = self.by_fd[fd]
 109         msgs = clnt.recv()
 110         result = []
 111         for msg in msgs:
 112             if isinstance(msg, LOGIN):
 113                 self.by_imei[clnt.imei] = clnt
 114             result.append((clnt.imei, msg))
 115         return result
 116
 117     def response(self, resp):
 118         if resp.imei in self.by_imei:
 119             self.by_imei[resp.imei].send(resp.payload)
 120
 121
 122 def runserver(opts, conf):
 123     zctx = zmq.Context()
 124     zpub = zctx.socket(zmq.PUB)
 125     zpub.bind(conf.get("collector", "publishurl"))
 126     zsub = zctx.socket(zmq.SUB)
 127     zsub.connect(conf.get("collector", "listenurl"))
 128     tcpl = socket(AF_INET, SOCK_STREAM)
 129     tcpl.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
 130     tcpl.bind(("", conf.getint("collector", "port")))
 131     tcpl.listen(5)
 132     tcpfd = tcpl.fileno()
 133     poller = zmq.Poller()
 134     poller.register(zsub, flags=zmq.POLLIN)
 135     poller.register(tcpfd, flags=zmq.POLLIN)
 136     clients = Clients()
 137     try:
 138         while True:
 139             tosend = []
 140             topoll = []
 141             tostop = []
 142             events = poller.poll(10)
 143             for sk, fl in events:
 144                 if sk is zsub:
 145                     while True:
 146                         try:
 147                             msg = zsub.recv(zmq.NOBLOCK)
 148                             tosend.append(Resp(msg))
 149                         except zmq.Again:
 150                             break
 151                 elif sk == tcpfd:
 152                     clntsock, clntaddr = tcpl.accept()
 153                     topoll.append((clntsock, clntaddr))
 154                 else:
 155                     for imei, msg in clients.recv(sk):
 156                         zpub.send(Bcast(imei, msg).as_bytes)
 157                         if msg is None or isinstance(msg, HIBERNATION):
 158                             log.debug("HIBERNATION from fd %d", sk)
 159                             tostop.append(sk)
 160             # poll queue consumed, make changes now
 161             for fd in tostop:
 162                 poller.unregister(fd)
 163                 clients.stop(fd)
 164             for zmsg in tosend:
 165                 clients.response(zmsg)
 166             for clntsock, clntaddr in topoll:
 167                 fd = clients.add(clntsock, clntaddr)
 168                 poller.register(fd)
 169     except KeyboardInterrupt:
 170         pass
 171
 172
 173 if __name__.endswith("__main__"):
 174     opts, _ = getopt(sys.argv[1:], "c:d")
 175     opts = dict(opts)
 176     conf = readconfig(opts["-c"] if "-c" in opts else CONF)
 177     if sys.stdout.isatty():
 178         log.addHandler(StreamHandler(sys.stderr))
 179     else:
 180         log.addHandler(SysLogHandler(address="/dev/log"))
 181     log.setLevel(DEBUG if "-d" in opts else INFO)
 182     log.info("starting with options: %s", opts)
 183     runserver(opts, conf)