174 lines
5.5 KiB
Python
174 lines
5.5 KiB
Python
from owrx.kiss import KissDeframer
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from owrx.map import Map, LatLngLocation
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from owrx.bands import Bandplan
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import logging
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logger = logging.getLogger(__name__)
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class Ax25Parser(object):
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def parse(self, ax25frame):
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control_pid = ax25frame.find(bytes([0x03, 0xf0]))
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if control_pid % 7 > 0:
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logger.warning("aprs packet framing error: control/pid position not aligned with 7-octet callsign data")
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def chunks(l, n):
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"""Yield successive n-sized chunks from l."""
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for i in range(0, len(l), n):
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yield l[i:i + n]
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return {
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"destination": self.extractCallsign(ax25frame[0:7]),
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"source": self.extractCallsign(ax25frame[7:14]),
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"path": [self.extractCallsign(c) for c in chunks(ax25frame[14:control_pid], 7)],
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"data": ax25frame[control_pid+2:]
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}
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def extractCallsign(self, input):
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cs = bytes([b >> 1 for b in input[0:6]]).decode().strip()
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ssid = (input[6] & 0b00011110) >> 1
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if ssid > 0:
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return "{callsign}-{ssid}".format(callsign=cs, ssid=ssid)
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else:
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return cs
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class AprsParser(object):
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def __init__(self, handler):
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self.ax25parser = Ax25Parser()
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self.deframer = KissDeframer()
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self.dial_freq = None
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self.band = None
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self.handler = handler
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def setDialFrequency(self, freq):
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self.dial_freq = freq
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self.band = Bandplan.getSharedInstance().findBand(freq)
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def parse(self, raw):
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for frame in self.deframer.parse(raw):
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data = self.ax25parser.parse(frame)
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# TODO how can we tell if this is an APRS frame at all?
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aprsData = self.parseAprsData(data)
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logger.debug(aprsData)
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if "lat" in aprsData and "lon" in aprsData:
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loc = LatLngLocation(aprsData["lat"], aprsData["lon"], aprsData["comment"] if "comment" in data else None)
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Map.getSharedInstance().updateLocation(data["source"], loc, "APRS", self.band)
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self.handler.write_aprs_data(aprsData)
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def hasCompressedCoordinatesx(self, raw):
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return raw[0] == "/" or raw[0] == "\\"
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def parseUncompressedCoordinates(self, raw):
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lat = int(raw[0:2]) + float(raw[2:7]) / 60
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if raw[7] == "S":
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lat *= -1
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lon = int(raw[9:12]) + float(raw[12:17]) / 60
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if raw[17] == "W":
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lon *= -1
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return {
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"lat": lat,
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"lon": lon,
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"symbol": raw[18]
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}
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def parseCompressedCoordinates(self, raw):
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def decodeBase91(input):
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base = decodeBase91(input[:-1]) * 91 if len(input) > 1 else 0
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return base + (ord(input[-1]) - 33)
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return {
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"lat": 90 - decodeBase91(raw[1:5]) / 380926,
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"lon": -180 + decodeBase91(raw[5:9]) / 190463,
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"symbol": raw[9]
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}
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def parseMicEFrame(self, data):
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information = data["data"]
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destination = data["destination"]
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def extractNumber(input):
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n = ord(input)
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if n >= ord("P"):
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return n - ord("P")
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if n >= ord("A"):
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return n - ord("A")
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return n - ord("0")
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def listToNumber(input):
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base = listToNumber(input[:-1]) * 10 if len(input) > 1 else 0
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return base + input[-1]
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logger.debug(destination)
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rawLatitude = [extractNumber(c) for c in destination[0:6]]
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logger.debug(rawLatitude)
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lat = listToNumber(rawLatitude[0:2]) + listToNumber(rawLatitude[2:6]) / 6000
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if ord(destination[3]) <= ord("9"):
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lat *= -1
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logger.debug(lat)
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logger.debug(information)
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lon = information[1] - 28
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if ord(destination[4]) >= ord("P"):
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lon += 100
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if 180 <= lon <= 189:
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lon -= 80
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if 190 <= lon <= 199:
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lon -= 190
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minutes = information[2] - 28
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if minutes >= 60:
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minutes -= 60
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lon += minutes / 60 + (information[3] - 28) / 6000
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if ord(destination[5]) >= ord("P"):
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lon *= -1
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return {
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"lat": lat,
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"lon": lon,
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"comment": information[9:].decode()
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}
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def parseAprsData(self, data):
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information = data["data"]
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# forward some of the ax25 data
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aprsData = {
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"source": data["source"],
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"destination": data["destination"],
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"path": data["path"]
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}
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if information[0] == 0x1c or information[0] == 0x60:
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aprsData.update(self.parseMicEFrame(data))
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return aprsData
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information = information.decode()
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logger.debug(information)
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if information[0] == "!" or information[0] == "=":
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# position without timestamp
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aprsData.update(self.parseRegularAprsData(information[1:]))
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elif information[0] == "/" or information[0] == "@":
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# position with timestamp
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# TODO parse timestamp
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aprsData.update(self.parseRegularAprsData(information[8:]))
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return aprsData
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def parseRegularAprsData(self, information):
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if self.hasCompressedCoordinatesx(information):
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aprsData = self.parseCompressedCoordinates(information[0:10])
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aprsData["comment"] = information[10:]
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else:
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aprsData = self.parseUncompressedCoordinates(information[0:19])
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aprsData["comment"] = information[19:]
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return aprsData
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