#!/usr/bin/ruby

require 'net/http'
Net::HTTP.version_1_2

# BEGIN ===== User setup section =====

# Account information
ID = 'your_id'
PASSWD = 'your_passwd'
HOST = 'your.host.com'

# How to get my current global IP ?
# If you can't understand what you should do,
# please comment out following paragraph,
# and simply write down, IP_CURRENT = nil.
IP_CURRENT = Proc.new{
	/(?:\d{1,3}\.){3}\d{1,3}/ =~ `/sbin/ifconfig ppp0`
	$&
}

# Program type setting
# auto background update(IS_DAEMON = true) / user manual update(IS_DAEMON = false) ?
IS_DAEMON = false
UPDATE_PEROID = 60 * 60 #[sec]
LOG_FILE = 'ip-updater.log'

# END   ===== User setup section =====

# Target Server URL
SRV_UPDATE_HOST = 'www.mydns.jp'
SRV_UPDATE_PATH = '/login.html'

# About this program
AGENT_NAME = 'Ruby-Updater'
AGENT_VERSION = '0.2'
AGENT_MODE = 'MD5'

# main program begins from the next line.

def update(ip_previous = nil)

	print("#{Time.now.to_s}, Trying...\n")

	ip_current = nil
	if IP_CURRENT
		ip_current = IP_CURRENT.call
	end
	
	# check IP whether the DDNS registered IP equals my current global IP.
	if ip_previous and ip_previous == ip_current then
		print "MESSAGE: No need to update, now DDNS.IP == IP_CURRENT\n"
		return ip_current
	end

	req = Net::HTTP::Get::new(SRV_UPDATE_PATH)
	req.basic_auth ID, PASSWD
	Net::HTTP.start(SRV_UPDATE_HOST) {|http|
		response = http.request(req)
		response.body.each{|line|
			if line =~ /(\d{1,3}\.){3}\d{1,3}/ then
				ip_current = $&
				break
			end
		}
	}
	print "MESSAGE: registered DDNS.IP as #{ip_current}\n"
	
	return ip_current
end

if IS_DAEMON then

	exit! if fork	# fork
	
	# log file setting
	log_file = File.open(LOG_FILE, 'w+')
	STDOUT.reopen(log_file)
	STDOUT.sync = true
	STDERR.reopen(log_file)
	STDERR.sync = true
	
	Signal.trap('HUP'){exit}
	Signal.trap('TERM'){exit}
	
	END{log_file.close}
	
	print("PID: #{Process.pid}\n")
	print("Start #{AGENT_NAME} at #{Time.now.to_s}\n")
	
	ObjectSpace.each_object(IO){|io|
		io.close unless io.closed? || io == log_file || io == STDOUT || io == STDERR
	}
	
	Process.setsid
	
	ip = nil
	loop{
		ip = update(ip)
		sleep(UPDATE_PEROID)
	}
else
	update
end