#!/usr/bin/env python
# $Id: hbc,v 1.9 2012/03/29 02:08:36 andreas Exp $

# require on Linux
#	python-filelock 
#	python-daemon vs 1.61 or >
# on *bsd
#	py27-lockfile 
# 	py-27-daemon
# or run  sudo easy_install-2.7 lockfile daemon
import sys
import time
import socket
import os
import signal
import getopt
import string
import select
import errno
import traceback
import lockfile 
import daemon
import daemon.pidfile
import syslog


PORT = 50003
INTERVAL = 10
PIDFILE = '/tmp/hbc.pid'
DBG = True

sock = None
up = True
ackcount = 0

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


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


def getsock(host):
	try:
		r=socket.getaddrinfo(host,  50001, 0, 0, socket.SOL_UDP)
	except socket.gaierror:
		return None
	if r[0][0] == 28:
		af_type=socket.AF_INET6
	elif r[0][0] == 2:
		af_type=socket.AF_INET
	else:
		return None
	if verbose:
		syslog.syslog("socktype: %s" % af_type)
	sock=socket.socket(af_type, socket.SOCK_DGRAM)
	sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR, \
            sock.getsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR) | 1)
	if verbose: syslog.syslog("get socket %s" % sock)
	
	return sock


def socksend(msg, tohost):
	global sock

	if sock == None:
		sock=getsock(tohost[0])
	sock.sendto(msg, tohost)
	if verbose: syslog.syslog("msg %s sent" % msg)


def process():
	global up, sock, ackcount

	if sock == None:
		sock=getsock(tohost[0])

	ackcount=0
	lastT=time.time()
	while up:
		sleep=(lastT+interval) - time.time() 
		if verbose: syslog.syslog("sleep %s" % sleep)
		if sleep > 0:
			try:
				r=select.select([sock.fileno()],[],[],sleep)
			except:
				if up:
					syslogtrace('select')
				break
			if verbose: syslog.syslog("r is %s" % str(r))
			if sock.fileno() in r[0]:
				data, addr = sock.recvfrom(1024)
				if  data == "ACK":
					ackcount+=1
				else:
					try:
						os.system(data)
					except:
						syslogtrace('System')
						pass
				continue	
		lastT=time.time()
		for hb_host in hb_hosts:
			try:
				msg="interval=%s;name=%s;time=%s;acks=%s" % (interval, iam, time.time(), ackcount)
				if verbose: syslog.syslog("sock.send('%s', (%s, %s))" % (msg, hb_host, hb_port))
				socksend(msg, (hb_host, hb_port))
			except:
				pass
	

def cleanup(a, b):
	global up, sock, ackcount
	up = False
	syslog.syslog('exit a=%s b=%s' % (str(a), str(b)))
	msg="shutdown=1;name=%s;acks=%s" % (iam, ackcount)
	for hb_host in hb_hosts:
		if verbose: syslog.syslog("hbc: sock.send('%s', (%s, %s))" % (msg, hb_host, hb_port))
		socksend(msg, (hb_host, hb_port))
	time.sleep(1)
	sock.close()


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

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

for o,a in optlist:
	if o == '-b':
		msgboot.append("boot=1")
	elif o == '-c':
		configfile=a
	elif o == '-d':
		fdaemon=True
	elif o == '-h':
		helpflag=True
	elif o == '-m':
		msgboot.append("service=%s" % "service")
		a.replace(';',':')
		msgboot.append("msg=%s" % a)
		msgonly=True
	elif o == '-v':
		verbose=True


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

if not msgonly:
	msgboot.append("interval=%s" % interval)

if len(msgboot) > 0:
	msgboot.append("name=%s" % iam)
	msgboot.append("time=%s" % time.time())
	msgboot.append("acks=0")
	msg=";".join(msgboot)
	while 1:
		fail=0
		for hb_host in hb_hosts:
			try:
				if verbose: print "sock.send('%s', (%s, %s))" % (msg, hb_host, hb_port)
				socksend(msg, (hb_host, hb_port))
			except:
				fail=1
		if fail:
			time.sleep(10)
		else:
			break
	
if verbose: print "msgboot done msgonly=%s" % msgonly
if msgonly:
		sys.exit(0)


#
# 
syslog.openlog(logoption=syslog.LOG_PID, facility=syslog.LOG_DAEMON)
if fdaemon:

	pidfile = daemon.pidfile.TimeoutPIDLockFile(PIDFILE, acquire_timeout=-1)
	try:
		opid = pidfile.read_pid()
	except:
		opid = None
	if verbose: print "opid %s" % opid

	if opid:
		try:
			os.kill(opid, 0)
			is_running = True
		except:
			is_running = False
		if verbose: print "is_running  %s" % is_running 
		if is_running:
			print "process still alive %s" % opid
			sys.exit(1)
		print "warning: stale pid file removed"
		os.unlink(PIDFILE)

	print "daemoinizing... %s" % os.getpid()
	context = daemon.DaemonContext(
		working_directory='/tmp',
		umask=0o002,
		pidfile=pidfile,
		)

	context.signal_map = {
		signal.SIGTERM: cleanup,
		signal.SIGHUP: 'terminate',
#		signal.SIGUSR1: reload_program_config,
		}

	context.files_preserve = [sock, sock.fileno()]
	with context:
		syslog.syslog('starting heartbeat to %s' %  ','.join(hb_hosts))
		up = True
		try:
			process()
		except:
			syslogtrace('process')
			cleanup(0, None)