238 lines
8.4 KiB
Python
Executable File
238 lines
8.4 KiB
Python
Executable File
#!/usr/bin/env python
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#
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# Copyright 2012 Nick Foster
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#
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# This file is part of gr-air-modes
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#
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# gr-air-modes is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3, or (at your option)
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# any later version.
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#
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# gr-air-modes is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with gr-air-modes; see the file COPYING. If not, write to
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# the Free Software Foundation, Inc., 51 Franklin Street,
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# Boston, MA 02110-1301, USA.
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#
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import time, os, sys, socket, struct
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from string import split, join
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from datetime import *
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import air_modes
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import pickle
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import time
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import bisect
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#simple multilateration server app.
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#accepts connections from clients (need a raw_client output thing)
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#looks at received messages and then attempts to multilaterate positions
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#will not attempt clock synchronization yet; it's up to clients to present
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#accurate timestamps. later on we can do clock sync based on ADS-B packets.
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#how to store records for quick retrieval?
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#the data is really a hash; we use it to find correlated records.
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#self._records should be a dict of replies
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#so: { <adsbdata>: [{ "addr": "192.168.10.1", "secs": 11, "frac_secs": 0.123456 }, {....}...] ... }
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#adsbdata should be an int.
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#change this to 0 for ASCII format for debugging. use HIGHEST_PROTOCOL
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#for actual use to keep the pickle size down.
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pickle_prot = 0
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#pickle_prot = pickle.HIGHEST_PROTOCOL
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class rx_data:
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def __init__(self):
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self.secs = 0
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self.frac_secs = 0.0
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self.data = None
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class stamp:
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def __init__(self, addr, secs, frac_secs):
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self.addr = addr
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self.secs = secs
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self.frac_secs = frac_secs
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def __lt__(self, other):
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if self.secs == other.secs:
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return self.frac_secs < other.frac_secs
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else:
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return self.secs < other.secs
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def __gt__(self, other):
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if self.secs == other.secs:
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return self.frac_secs > other.frac_secs
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else:
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return self.secs > other.secs
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def __eq__(self, other):
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return self.secs == other.secs and self.frac_secs == other.frac_secs
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def __ne__(self, other):
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return self.secs != other.secs or self.frac_secs != other.frac_secs
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#good to within ms for comparison
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def tofloat(self):
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return self.secs + self.frac_secs
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def ordered_insert(a, item):
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a.insert(bisect.bisect_right(a, item), item)
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class client_info:
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def __init__(self):
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self.name = ""
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self.latitude = 0.0
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self.longitude = 0.0
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self.altitude = 0.0
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self.offset_secs = 0
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self.offset_frac_secs = 0.0
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class connection:
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def __init__(self, addr, sock, clientinfo):
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self.addr = addr
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self.sock = sock
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self.clientinfo = clientinfo
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class mlat_server:
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def __init__(self, mypos, port):
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self._s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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self._s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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self._s.bind(('', port))
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self._s.listen(1)
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self._s.setblocking(0) #nonblocking
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self._conns = [] #list of active connections
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self._reports = {} #hashed by data
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self._lastreport = 0 #used for pruning
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self._parser = air_modes.parse(None)
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def __del__(self):
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self._s.close()
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def get_messages(self):
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for conn in self._conns:
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pkt = None
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try:
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pkt = conn.sock.recv(1024)
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except socket.error:
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self._conns.remove(conn)
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if not pkt: break
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#try:
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msglist = pickle.loads(pkt)
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for msg in msglist:
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#DEBUG: change conn.clientinfo.name to conn.addr for production
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st = stamp(conn.clientinfo.name, msg.secs, msg.frac_secs)
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if msg.data not in self._reports:
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self._reports[msg.data] = []
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#ordered insert
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ordered_insert(self._reports[msg.data], st)
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self._lastreport = st.tofloat()
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# for report in self._reports.values():
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# for st in report:
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# print st.addr, st.secs, st.frac_secs
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#except Exception as e:
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# print "Invalid message from %s: %s" % (conn.addr, pkt)
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# print e
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#self.prune()
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#prune should delete all reports in self._reports older than 5s.
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#how do we get the appropriate time? we either trust the reporting
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#stations, or we use UTC.
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#if we assume all stations are using UTC, we can prune on UTC, but
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#this computer has to be closely synchronized as well
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def prune(self):
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for report in self._reports:
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if self._reports[report][-1].tofloat() - self._lastreport > 5:
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self._reports.remove(report)
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#return a list of eligible messages for multilateration
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#eligible reports are:
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#1. bit-identical
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#2. from distinct stations (at least 3)
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#3. within 0.001 seconds of each other
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#traverse the reports for each data pkt (hash) looking for >3 reports
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#within 0.001s, then check for unique IPs (this should pass 99% of the time)
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#let's break a record for most nested loops. this one goes four deep.
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#it's loop-ception!
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def get_eligible_reports(self):
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groups = []
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for data,stamps in self._reports.iteritems():
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if len(stamps) > 2: #quick check before we do a set()
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stations = set([st.addr for st in stamps])
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if len(stations) > 2:
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i=0
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#it's O(n) since the list is already sorted
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#can probably be cleaner and more concise
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while(i < len(stamps)):
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refstamp = stamps[i].tofloat()
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reps = []
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while (i<len(stamps)) and (stamps[i].tofloat() < (refstamp + 0.001)):
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reps.append(stamps[i])
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i+=1
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deduped = []
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for addr in stations:
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for st in reps[::-1]:
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if st.addr == addr:
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deduped.append(st)
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break
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if len(deduped) > 2:
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groups.append({"data": data, "stamps": deduped})
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if len(groups) > 0:
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return groups
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return None
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#issue multilaterated positions
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def output(self, msg):
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#do something here to compose a message
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if msg is not None:
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try:
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for conn in self._conns[:]: #iterate over a copy of the list
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conn.sock.send(msg)
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except socket.error:
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print "Client %s disconnected" % conn.clientinfo.name
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self._conns.remove(conn)
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print "Connections: ", len(self._conns)
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#add a new connection to the list
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def add_pending_conns(self):
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try:
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conn, addr = self._s.accept()
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conn.send("HELO\n") #yeah it's like that
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msg = conn.recv(1024)
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if not msg:
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return
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try:
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clientinfo = pickle.loads(msg)
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except:
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print "Invalid pickle received from client"
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return
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if clientinfo.__class__.__name__ != "client_info":
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print "Invalid datatype received from client"
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return
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conn.send("OK")
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self._conns.append(connection(addr[0], conn, clientinfo))
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print "New connection from %s: %s" % (addr[0], clientinfo.name)
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except socket.error:
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pass
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if __name__=="__main__":
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srv = mlat_server("nothin'", 31337)
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while 1:
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srv.output("Buttes")
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srv.get_messages()
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srv.add_pending_conns()
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reps = srv.get_eligible_reports()
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if reps:
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for rep in reps:
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print "Report with data %x" % rep["data"]
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for st in rep["stamps"]:
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print "Stamp from %s: %f" % (st.addr, st.tofloat())
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srv.prune()
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time.sleep(0.3)
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