#!/usr/bin/env python
# $Id: hbc,v 1.9 2012/03/29 02:08:36 andreas Exp $
# NEW
import sys
import time
import socket
import os
import signal
import getopt
import string
import select
import errno
import traceback
from hashlib import md5
import shutil
import zlib
import subprocess
import syslog

import syslog


PORT = 50003
INTERVAL = 10
REOPENC = 6
PIDFILE = '/tmp/hbc.pid'
VER = 5
MAXRECV = 32767

running = True
dorestart = False
warned1 = False

def log(msg):
	if fdaemon:
		syslog.syslog(syslog.LOG_ERR, msg)
	else:
		print(msg)

def handler(signum, frame):
	if signum == signal.SIGTERM:
		cleanup()		

class NullDevice:
	def write(self, s):
		pass


class Conn:
	def __init__(self, conId, addr, port, af):
		self.conId = conId
		self.addr = addr
		self.port = port
		self.af = af

		self.ackcount = 0		# num of accks received
		self.lastack = 0		# time() last ACK was received
		self.send = 0
		self.lastsend = 0		# time() last msg was sent
		self.rtts = [0]
		self.sock = None


	def __str__(self):
		return "Con(%s, %s %s)" % (self.addr, self.port, self.af)


	def open(self):
		self.sock=socket.socket(self.af, socket.SOCK_DGRAM)
		self.sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR, \
 			self.sock.getsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR) | 1)


	def sendto(self, msg, ID = 'HTB'):		# default ID is HearTBeat
		global warned1

		if self.send % REOPENC == 0:
			self.close()
		if not self.sock:
			self.open()
		msg['name'] = shortname(iam)
		msg['id'] = self.conId
		msg['ver'] = VER
		msg['time'] = time.time()
		m = dicttos(ID, msg)			# always compress
		if verbose:
			log("conn.send('%s', (%s:%s) %s)" % (msg, self.addr, self.port, len(m)))
		try:
			self.sock.sendto(m, (self.addr, self.port))
		except socket.error as e:
			if not warned1: log("socket error: %s %s:%s" % (e, self.addr, self.port))
			warned1 = True
			self.close()
			return
		self.send += 1
		self.lastsend = time.time()


	def ack(self, msgDict, now):
		try:
			self.lastack = msgDict['time'] 
			mul = 2
		except:
			self.lastack = now
			mul = 1
		rtt = (self.lastack - self.lastsend) * mul
		if verbose: log("ack RTT: %0.1f ms (now %s)" % (rtt * 1000.0, now))
		self.rtts.append(rtt * 1000.0)
		if len(self.rtts) > 10:
			del self.rtts[0]
		self.ackcount += 1


	def close(self):
		if self.sock:
			self.sock.close()
		self.sock = None


def shortname(name):
	r = name.split('.')
	return r[0]


def dicttos(ID, d):
	s = []
	for k in d:
		if type(d[k]) == type(1.2):
			s.append("%s=%0.5f" % (k, d[k]))
		else:
			s.append("%s=%s" % (k, d[k]))
	pk = ";".join(s)
	zpk = zlib.compress(pk.encode(), 6)
	ID = "!" + ID + ":"
	return ID.encode() + zpk

def stodict(msg):
	d = {}
	if len(msg) > 0 and chr(msg[0]) == "!":
		pk = zlib.decompress(msg[5:]).decode()
		d['ID'] = msg[1:4].decode()
	else:
		r0 = msg.split(':',1)
		pk = r0[1]
		d['ID'] = r0[0]
	r = pk.split(';')
	for v in r:
		vr = v.split('=', 1)
		k = vr[0].strip()
		if len(vr) == 1:
			d[k] = None
		else:
			v = vr[1].strip()
			if v[0].isdigit():
				v = eval(v)
			d[k] = v
	if verbose: print("msg is %s" % d)
	return d


def XXstodict(msg):
	d = {}
	r0 = msg.split(':',1)
	if len(r0) == 1:
		return None
	if r0[0][0] == '!':		# compressed
		pk = zlib.decompress(msg[len(r0[0])+1:])
		d['ID'] = r0[0][1:]
	else:
		pk = r0[1]
		d['ID'] = r0[0]
	r = pk.split(';')
	for v in r:
		vr = v.split('=', 1)
		k = vr[0].strip()
		if len(vr) == 1:
			d[k] = None
		else:
			v = vr[1].strip()
			try:
				if v[0].isdigit():
					v = eval(v)
			except:
				pass
			d[k] = v
	return d


def syslogtrace(note):
	logm = '%s hbc died: \n%s' % (note, traceback.format_exc())
	log(logm)
	for l in logm.split('\n'):
		syslog.syslog(syslog.LOG_ERR, ' tb: %s' % l)
	if verbose:
		print(logm)
 

conId = 1
def createConnections(hosts):
	global conId
	for host in hosts:
		if verbose: log("createConnections for %s" % host)
		try:
			rs=socket.getaddrinfo(host, hb_port, 0, 0, socket.SOL_UDP)
		except socket.gaierror:
			logm = '%s hbc died: \n%s' % ('createConnections', traceback.format_exc())
			if verbose: log(logm)
			return None
		for r in rs:
			if verbose: log("address %s" % str(r))
			if r[0] in [10, 24, 28, 30]:	# for Linux, NetBSD, FreeBSD
				af=socket.AF_INET6
			elif r[0] == 2:
				af=socket.AF_INET
			else:
				print("dont know this net type: %s" % r[0][0])
				sys.exit(1)
	
			addr = r[4][0]
			conns[conId] = Conn(conId, addr, hb_port, af)
			if verbose: 
				print("cons[%s] = %s" % (conId, str(conns[conId])))
			conId += 1


def doexec(conn, data):
	try:
		ro = subprocess.check_output(data, stderr=subprocess.STDOUT, shell=True)
		fail = "OK"
	except subprocess.CalledProcessError as e:
		ro = str(e)
		fail = "CalledProcessError"
	except Exception as e:
		syslogtrace('System')
		ro = "N/A"
		fail = "cmd failed: %s" % e
	msg={'service': 'command', 'msg': fail+" "+ro}
	conns[conn].sendto(msg)


def doupdate(conn, msgDict):
	fail = None
	try:
		code = msgDict['code'].decode('base64')
		csum = msgDict['csum']
	except:
		fail = "csum/code missing"
	if not fail:
		fail = doupdateone(code, csum)

	msg={'service': 'update', 'msg': fail if fail else "OK"}
	conns[conn].sendto(msg)
	if not fail:
		log('hc updates, fs = %s' % (len(code)))
		
	return fail


def doupdateone(code, csum):

	m = md5.new()
	m.update(code)
	icsum = m.hexdigest()
	if icsum != csum:
		return "checksum error"

	fn = sys.argv[0]
	ofn = "%s.sav" % fn
	try:
		shutil.copy2(fn, ofn)
	except Exception as e:
		return "cannot make backup copy: %s" % e

	try:
		fh=open(fn, "w")
		fh.write(code)
		fh.close()
	except Exception as e:
		return "cannot write new code: %s" % e

	return None


def restart():
	if verbose: 
		print("restart: execv %s %s" % (sys.argv[0], [sys.argv[0]]+cmdargs))
	syslog.syslog(syslog.LOG_ERR, 'restart %s' % (sys.argv[0]))
	e = "fallthrough" 
	try:
		os.execv(sys.argv[0], [sys.argv[0]]+cmdargs)
	except Exception as e:
		pass
	print("should not be here:", str(e))
	log('restart failed: %s' % e)


def process():
	global running, dorestart

	nextReport = time.time()

	while running:
		while time.time() < nextReport:
			ifiles = {}
			conIds = {}
			for conn in conns:
				if conns[conn].sock:
					ifiles[conns[conn].sock.fileno()] = conns[conn].sock
					conIds[conns[conn].sock.fileno()] = conn

			sleep=nextReport - time.time() 
			if sleep <= 0:
				break
			try:
				r=select.select(list(ifiles.keys()),[],[],sleep)
				now = time.time()	# nb: delay from actual packet arrival to select is ca. 105ms!
			except KeyboardInterrupt:
				running = False
				break
			except SystemExit:
				log('daemon exit, running was %s' % running)
				if running:
					running = False
				break
			except:
				if running:
					syslogtrace('select')
					running = False
				break
			for rfh in r[0]:
				conn = conIds[rfh]
				data, addr = ifiles[rfh].recvfrom(MAXRECV)
#				if verbose: print("sock.recvfrom: %s (%s) %s" % (addr, len(data), data[:4]))
				try:
					msgDict = stodict(data)
				except Exception as e:
					print("failed to parse incoming data from %s: " % (addr, data))
					continue
				
				if verbose: print("sock.recvfrom: %s (%s) %s" % (addr, len(data), str(msgDict)[:80]))
				if msgDict == None:
					 print("bad backet from %s (%s) %s" % (addr, len(data), data))
				elif msgDict['ID'] == "ACK":
					conns[conn].ack(msgDict, now)
				elif msgDict['ID'] == "UPD":
					if doupdate(conn, msgDict) == None:
						if verbose: print("process: restart after update")
						dorestart = True
						break
				elif msgDict['ID'] == "CMD":
					doexec(conn, msgDict['cmd'])	
				else:
					doexec(conn, data)	# deprecated until no more VER - hbc
			if dorestart:
				running = False
				break
		if not running:
			break
		for conn in conns:
			msg={'acks': conns[conn].ackcount, 'rtt': conns[conn].rtts[-1]}
			conns[conn].sendto(msg)
			time.sleep(0.1)		#N.B. Linux (i.e. Rasperry Pi 3 drops the second pkg unless delayed
		if nextReport + interval >= time.time():
			nextReport += interval
		else:
			nextReport = time.time() + interval

	if verbose: log( "process: done running")

def cleanup():
	global running
	if not running:
		return
	if verbose: log('cleanup')
	running = False
	for conn in conns:
		msg={'shutdown': 1, 'acks': conns[conn].ackcount}
		conns[conn].sendto(msg)
		conns[conn].close()
	time.sleep(1)
	closeall()


def closeall():
	if verbose: syslog.syslog(syslog.LOG_ERR, 'closecall')
	for conn in conns:
		conns[conn].close()


def daemonize(working_dir="/", stdin='/dev/zero', stdout='/dev/null', stderr='/dev/null'):
	"""
	Does the UNIX double-fork magic, see Stevens' "Advanced Programming in the
	UNIX Environment" for details (ISBN 0201563177)
	http://www.yendor.com/programming/unix/apue/proc/fork2.c
	"""

	try:
		# first fork
		pid = os.fork()
		if pid > 0:
			# exit from first parent
			os._exit(0)
	except OSError as e:
		sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
		os._exit(1)

	# decouple from parent environment
	os.chdir(working_dir)
	os.setsid()
	os.umask(0)
	# second fork
	try:
		pid = os.fork()
		if pid > 0:
			# exit from second parent
			os._exit(0)
	except OSError as e:
		sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
		sys.exit(1)

	# redirects standard file descriptors
	sys.stdout.flush()
	sys.stderr.flush()
	si = open(stdin, 'r')
	so = open(stdout, 'a+')
	se = open(stderr, 'a+')
	os.dup2(si.fileno(), sys.stdin.fileno())
	os.dup2(so.fileno(), sys.stdout.fileno())
	os.dup2(se.fileno(), sys.stderr.fileno())



msgonly=False
helpflag=False
verbose=False
fdaemon=False
daemonized = False
optlist=[]
args=[]
msgboot={}
home=os.environ['HOME']
configfile="%s/.hbrc" % home
cmdargs = []


try:
	optlist, args = getopt.getopt(sys.argv[1:], 'bc:dhm:v')
except:
	helpflag=True

for o,a in optlist:
	if o == '-b':
		msgboot['boot']=1
	elif o == '-c':
		configfile=a
		cmdargs += [o, a]
	elif o == '-d':
		fdaemon=True
		cmdargs += [o]
	elif o == '-h':
		helpflag=True
	elif o == '-m':
		msgboot['service'] = "service"
		msgboot['msg'] = a
		msgonly=True
	elif o == '-v':
		verbose=True
		cmdargs += [o]


cmdargs += args
if verbose: print("cmdargs for restart are %s" % cmdargs)

if helpflag:
	print("hbc HeartBeatClient")
	print("usage: hbc [-bdhv] [-c configfile] [-m msg][host1 [..]]")
	print()
	print("	-b	indicate machine boot")
	print("	-c configfile")
	print("	-d daemonize")
	print("	-h this help")
	print("	-m send a message")
	print("	-v verbose")
	print()
	print(""" config file can contain 
hb_hosts=('host1', 'host2', ..._
hb_port=50003
interval=20
logfile=...
logfmt={|test|msg}
grace=SECONDS
reportstrict={True|False}
""")

	sys.exit(1)

#
# set defaults

hb_port=PORT
interval=INTERVAL
hb_hosts=[]
iam=socket.gethostname()

try:
	f=open(configfile,"r")
	if verbose: print("notice: using config file %s" % configfile)
except:
	if verbose: print("warning: running without config file: %s" % configfile)
	f=None

if f:
	while 1:
		l=f.readline()
		if len(l) == 0:
			break
		r=l[:-1].split('=')
		if r[0] == 'hb_hosts':
			hb_hosts=eval(r[1])
			if verbose:
				print("notice: cfg hb_hosts: %s" % hb_hosts)
		elif r[0] == 'interval':
			interval=eval(r[1])
		elif r[0] == 'hb_port':
			hb_port=eval(r[1])
		elif r[0] == 'name':
			iam=eval(r[1])
			if verbose: print("name set to %s" % iam)
	f.close()

if len(args) != 0:
	hb_hosts=args
	

if len(hb_hosts) == 0:
	print("no hb server specified")
	sys.exit(1)

# 
if verbose:
	print("notice: hb_hosts: %s" % str(hb_hosts))
	print("notice: hb_port: %s" % hb_port)
	print("notice: interval: %s" % interval)
	print("notice: iam: %s" % iam)
	print("notice: msgonly: %s" % msgonly)
	print("notice: msgboot: %s" % msgboot)

if not msgonly:
	msgboot['interval'] = interval


conns = {}
while True:
	if verbose: log("create connections")
	createConnections(hb_hosts)
	if len(conns) != 0:
		break
	if verbose: log("no connections yet, sleep a bit")
	time.sleep(2)

if verbose:
	log("%s connections created" % (len(conns)))

if len(msgboot) > 0:
	if verbose: print("on boot")
	msgboot['acks'] = 0 
	for conn in conns:
		conns[conn].sendto(msgboot)

if msgonly:
	if verbose: print("msgboot done msgonly=%s" % msgonly)
	closeall()
	sys.exit(0)

# 
syslog.openlog('hbc', syslog.LOG_PID, syslog.LOG_DAEMON)
if fdaemon:
	print("daemoinizing.")
	daemonize()
	daemonized = True
	syslog.syslog(syslog.LOG_ERR, 'starting heartbeat to %s' % ','.join(hb_hosts))

signal.signal(signal.SIGTERM, handler)
running = True
try:
	process()
except:
	syslogtrace('process')
	if verbose: print("err: process exit: %s" % e)

if verbose: log( "main: cleanup")
cleanup()
if dorestart:
	restart()