iR-APRSISD/ir-aprsisd

#!/usr/bin/python3

############################################################################
##
## ir-aprsisd
##
##	This is a KML-feed to APRS-IS forwarding daemon.  It was written
##	for Garmin/DeLorme inReach devices, but might work elsewhere too.
##	It polls a KML feed in which it expects to find a point in rougly
##	the form that the inReach online feeds use, with attendant course
##	and altitude data.  It transfers each new point found there to 
##	APRS-IS.
##
##	K0SIN
##
###########################################################################


import aprslib
import urllib.request
import xml.dom.minidom
import time, calendar, math, re
import platform, sys, signal
import configparser
from optparse import OptionParser


#Name of our configuration file.
cf = "ir-aprsisd.cfg"

#Command-line options
op = OptionParser()

op.add_option("-C","--config",action="store",type="string",dest="config",help="Load the named configuration file.")
op.add_option("-s","--ssid",action="store",type="string",dest="ssid",help="APRS SSID")
op.add_option("-p","--pass",action="store",type="int",dest="passwd",help="APRS-IS password")
op.add_option("--port",action="store",type="int",dest="port",help="APRS-IS port")
op.add_option("-u","--user",action="store",type="string",dest="user",help="inReach username")
op.add_option("-P","--irpass",action="store",type="string",dest="irpass",help="inReach feed password")
op.add_option("-U","--url",action="store",type="string",dest="url",help="URL for KML feed")
op.add_option("-i","--imei",action="store",type="int",dest="imei",help="This instance should watch *only* for the single IMEI given in this option.  For a more complicated mapping, use the Device section in the configuration file.")
op.add_option("-c","--comment",action="store",type="string",dest="comment",help="APRS-IS location beacon comment text")
op.add_option("-d","--delay",action="store",type="int",dest="delay",help="Delay between polls of KML feed")
op.add_option("--genpass",action="store_true",dest="genpass",help="Generate the correct passcode for the SSID given in the configuration, or on the command line, print it, and exit.")
(opts,args) = op.parse_args()

#Handle term and int signals
def trapexit(_signo,_stack_frame):
	print()
	print("Exiting.")
	sys.exit(0)

signal.signal(signal.SIGTERM,trapexit)
signal.signal(signal.SIGINT,trapexit)

#This needs to be defined before the load below happens.
#Load a configuration file, and try to validate that it is loaded.
def loadConfig(cfile):
	global conf
	conf = configparser.ConfigParser()
	if conf.read(cfile):
		if conf.has_section('General'):
			return True
	return False


#Handle loading of the configuration file first.
#Other command-line options may override things defined in the file.
if opts.config:
	if not loadConfig(opts.config):
		print("Can't load configuration: " + opts.config)
		sys.exit(1)
else:	#Default behavior if no file specified.
	if not loadConfig("/etc/" + cf):
		if not loadConfig(cf):
			print("Can't find default configuration: " + cf)
			sys.exit(1)

#Allow command-line arguments to override the config file.
if opts.ssid:
	conf['APRS']['SSID'] =		opts.ssid
if opts.passwd:
	conf['APRS']['Password'] =		str(opts.passwd)
if opts.port:
	conf['APRS']['Port'] =		str(opts.port)
if opts.user:
	conf['inReach']['User'] = 	opts.user
if opts.irpass:
	conf['inReach']['Password'] = 	opts.irpass
if opts.url:
	conf['inReach']['URL'] = 	opts.url
if opts.comment:
	conf['APRS']['Comment'] =	opts.comment
if opts.delay:
	conf['General']['Period'] =	opts.delay

#SSID should be standardized to upper-case.
conf['APRS']['SSID'] = conf['APRS']['SSID'].upper()

#Running in passcode generator mode.
if opts.genpass:
	print("Using SSID: " + conf['APRS']['SSID'])
	print("The passcode is: " + str(aprslib.passcode(conf['APRS']['SSID'])))
	print()
	sys.exit(0)


#Handle the special case where we've specified an IMEI on the command-line
if opts.imei:
	conf['Devices'] = {}
	conf['Devices'][conf['APRS']['SSID']] = str(opts.imei)

#Get the number and call from from the default SSID
#If we have multiple devices with non-specific ID mapping, we'll make it up
# from this.
(Call,SSNum) = re.search('(\w+)-(\d+)$',conf['APRS']['SSID']).groups()
SSNum = int(SSNum)

#The beginning of our APRS packets should contain a source, path, 
# q construct, and gateway address.  We'll reuse the same SSID as a gate.
# This is the part between the source and the gate.
ARPreamble	= ''.join(['>APRS,','TCPIP*,','qAS,',conf['APRS']['SSID']])

NAME		= "iR-APRSISD"
REV		= "0.3"

#Set up the handler for HTTP connections
if conf.has_option('inReach','Password'):
	passman		= urllib.request.HTTPPasswordMgrWithDefaultRealm()
	passman.add_password(None, conf['inReach']['URL'],'',conf['inReach']['Password'])
	httpauth	= urllib.request.HTTPBasicAuthHandler(passman)
	http		= urllib.request.build_opener(httpauth)
else:
	http		= urllib.request.build_opener()
urllib.request.install_opener(http)

#Handle connection to APRS-IS
def reconnect():
	global AIS
	while True:
		AIS = aprslib.IS(conf['APRS']['SSID'],passwd=conf['APRS']['Password'],port=conf['APRS']['Port'])
		try:
			AIS.connect()
			break
		except Exception as e:
			print("Trouble connecting to APRS-IS server.")
			print(e)
			time.sleep(3)
			continue

#We'll store the device to ssid mapping here.
SSIDList = {}
#We'll store timestamps here
lastUpdate = {}

#Load any preconfigured mappings
if conf.has_section('Devices'):
	for device in conf['Devices'].keys():
		SSIDList[conf['Devices'][device]] = device.upper()
		

#Get an SSID
#An apocryphal concern is that this will happily generate an SSID for None,
#	or whatever else might get passed along to it.
# There's a record in the usual set of inReach Placemarks where this happens,
# but because the record has no extended data, no packets are ever generated
# for it. Such a record is generally not interesting and on the end of the list,
# so there has been no reason to explicitly skip it.
def getSSID(DID):
	global lastUpdate, SSIDList, SSNum, Call
	#If we have a Devices section, the SSID list is static.
	if DID not in SSIDList:
		if conf.has_section('Devices'):
			return None
		SSIDList[DID] = ''.join([Call,"-",str(SSNum)])
		SSNum = SSNum + 1
	#Add a timestamp on the first call
	# This prevents us from redelivering an old message, which can stay
	# in the feed.
	if DID not in lastUpdate:
		lastUpdate[DID] = calendar.timegm(time.gmtime())
	return SSIDList[DID]


#APRS-IS Setup
AIS = None
reconnect()

#Get information from a Placemark
def parsePlacemark(Placemark):
	#We only care about the Placemarks with the ExtendedData sections.
	if not Placemark.getElementsByTagName('ExtendedData'):
		return None
		
	#Now process the extended data into something easier to handle.
	extended = {}
	for xd in Placemark.getElementsByTagName('ExtendedData')[0].getElementsByTagName('Data'):
		if not xd.getElementsByTagName('value')[0].firstChild == None:
			extended[xd.getAttribute('name')] = xd.getElementsByTagName('value')[0].firstChild.nodeValue	

	#Make sure the device mapping is good.
	if not 'IMEI' in extended:
		return None
	if not getSSID(extended['IMEI']):
		return None

	#Now build the position vector
	latitude	= None
	longitude	= None
	elevation	= None
	velocity	= None
	course		= None
	uttime		= None
	device		= None
	IMEI		= extended['IMEI']

	if 'Latitude' in extended and 'Longitude' in extended:
		latitude	= float(extended['Latitude'])
		longitude	= float(extended['Longitude'])
	if 'Elevation' in extended:
		#Altitude needs to be in feet above sea-level
		# what we get instead is a string with a number of meters
		# at the beginning.
		elevation       = re.sub(r'^(\d+\.?\d+)\s*m.*',r'\1',extended['Elevation'])
		elevation       = float(elevation) * 3.2808399
	if 'Velocity' in extended:
		#Velocity in knots, according to APRS.
		velocity	= float(re.sub(r'(\d+\.?\d+).*',r'\1', extended['Velocity']))*0.5399568
	if 'Course' in extended:
		#... and the course is just a heading in degrees.
		course		= float(re.sub(r'(\d+\.?\d+).*',r'\1', extended['Course']))
	uttime		= time.strptime(extended['Time UTC'] + " UTC","%m/%d/%Y %I:%M:%S %p %Z")
	device		= extended['Device Type']

	#If we have SMS data, add that.
	if 'Text' in extended:
		comment = extended['Text']
	else:	#Default comment
		comment = conf['APRS']['Comment']

	return [device,IMEI,ARPreamble,uttime,latitude,longitude,elevation,course,velocity,comment]

#Return a list of all events available.  Each one is a list of arguments
# for the below sendAPRS function
def getEvents():
	events = []
	try:
		KML = http.open(conf['inReach']['URL']).read()
	except Exception as e:
		print("Error reading URL: " + conf['inReach']['URL'])
		return None
	try:
		data = xml.dom.minidom.parseString(KML).documentElement
	except Exception as e:
		print("Can't process KML feed on this pass.")
		return None
	#The first placemark will have the expanded current location information.
	for PM in data.getElementsByTagName('Placemark'):
		res = parsePlacemark(PM)
		if res:
			events.append(res)
	return events

#Compile and send an APRS packet from the given information
#According to spec, one valid format for location beacons is
# @092345z/4903.50N/07201.75W>088/036
# with a comment on the end that can include altitude and other
# information.
## Arguments are:
#	Device type, Device ID, APRS Preamble, struct Timestamp, float Latitude
#	float Longitude, float Altitude in feet, int float course in degrees,
#	float speed in knots, comment
def sendAPRS(device, DevID, ARPreamble, tstamp, lat, long, alt, course, speed, comment):
	global		conf
	etime		= calendar.timegm(tstamp)

	#Latitude conversion
	#We start with the truncated degrees, filled to two places
	# then add fractional minutes two 2x2 digits.
	slat		= str(abs(math.trunc(lat))).zfill(2)
	slat		+= '{:.02f}'.format(round((abs(lat)-abs(math.trunc(lat)))*60,2)).zfill(5)
	if lat > 0:
		slat += "N"
	else:
		slat += "S"

	#Longitude        
	slong	= str(abs(math.trunc(long))).zfill(3)
	slong	+= '{:.02f}'.format(round((abs(long)-abs(math.trunc(long)))*60,2)).zfill(5)
	if long > 0:
		slong += "E"
	else:
		slong += "W"

   
	pos		= ''.join([slat,conf['APRS']['Separator'],slong,conf['APRS']['Symbol']])
	gateInfo	= ''.join([" ", comment, " : ", NAME, " v", REV, " : ", platform.system(), " on ", platform.machine(), " : "])
	
	if device:
		gateInfo = gateInfo + device

	#In the format we're using, APRS comments can be 36 characters
	# ... but APRS-IS doesn't seem to care, so leave this off.
	#comment	= comment[:36]

	aprsPacket	= ''.join([getSSID(DevID),ARPreamble, ':@', time.strftime("%d%H%Mz",tstamp), pos]) 

	#Check to make sure the update is new:
	if lastUpdate[DevID] > etime:
		return None

	#In theory a course/speed of 000/000 sholdn't be much different
	# from not reporting one, but also in theory, more space is 
	# available for a comment if we don't add the data extension.
	if speed and course:
		aprsPacket	= ''.join([aprsPacket,str(round(course)).zfill(3), '/', str(min(round(speed),999)).zfill(3)])
	#Same with altitude:
	if alt:
		#We need six digits of altitude.
		aprsPacket	= aprsPacket + "/A=" + str(round(alt)).zfill(6)[0:6]
	# Regardless:
	aprsPacket		= aprsPacket + comment + gateInfo
	try:
		aprslib.parse(aprsPacket)	# For syntax
		AIS.sendall(aprsPacket)
	except Exception as e:
		print("Could not send APRS packet: ")
		print(aprsPacket)
		print("Attempting reconnect just in case.")
		reconnect()
		pass
	#Last update in UTC
	lastUpdate[DevID]	= calendar.timegm(tstamp)

#... and here is the main loop.
while True:
	for packet in getEvents():
		sendAPRS(*packet)	#Otherwise a list of sendAPRS args for the next packet to send.
	time.sleep(conf.getfloat('General','Period'))