#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Copyright (c) 2009, Markus Stumpf
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
#     * Redistributions of source code must retain the above copyright notice,
#       this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above copyright
#       notice, this list of conditions and the following disclaimer in the
#       documentation and/or other materials provided with the distribution.
#     * Neither the name of Markus Stumpf nor the names of its contributors may
#       be used to endorse or promote products derived from this software
#       without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

import os
import sys
import ConfigParser
import getopt
import httplib
from xml.dom import minidom
import time
try:
    import dns.query
    import dns.tsigkeyring
    import dns.update
except:
    print "Error: need dnspython package to run. see http://www.dnspython.org/"
    sys.exit(1)

__version__	= '1.0'
__author__	= 'Markus Stumpf <srv-src-pydnsup@maexotic.de>'

TFORM_RFC3339 = '%FT%T'
TFORM_RFC3339 = '%F %T'
DEFAULT_CONFIGFILE = "/etc/pydnsup/pydnsup.conf"

class dnsupdater:
    def __init__(self, configfile=DEFAULT_CONFIGFILE, debug=False):
	self._o_debug = debug
        self.readConfig(configfile)

    def __writemsg(self, message):
	sys.stderr.write(message.encode('utf-8'))
	if "\n" != message[-1]:
            sys.stderr.write("\n")

    def _error(self, message):
	self.__writemsg("Error: " + message)

    def _info(self, message):
	self.__writemsg("Info: " + message)

    def _debug(self, message):
	self.__writemsg("Debug: " + message)

    def readConfig(self, configfile):
	'''read the configuration file'''

	config = ConfigParser.ConfigParser()
	
	if not os.path.isfile(configfile):
	    self._error("configfile '%s' does not exist" % (configfile))
	    sys.exit(1)

	if self._o_debug:
	    self._debug("parsing config file '%s' ..." %(configfile))

	try:
            config.read(configfile)
	    self._dns_keyname	= config.get("dns", "keyname")
	    self._dns_keyvalue	= config.get("dns", "keyvalue")
	    self._dns_host	= config.get("dns", "host")
	    self._dns_domain	= config.get("dns", "domain")
	    self._dns_ttl	= config.getint("dns", "ttl")
	    self._dns_serverip	= config.get("dns", "serverip")
	    self._dns_addtxt	= config.getboolean("dns", "addtxt")
	    self._dns_timeout	= config.getfloat("dns", "timeout")

	    self._router_ip		= config.get("router", "ip")
	    self._router_port		= config.getint("router", "port")
	    self._router_http_req	= config.get("router", "http_req")

	except Exception, e:
	    self._error("error reading configuration: %s" % (e))
	    sys.exit(1)

    def upnp_info(self, action, result):
	'''get the external IP address via UPnP from the router'''

	reqBody = """\
<?xml version="1.0" encoding="utf-8"?>
<s:Envelope
   xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"
   s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
  <s:Body>
    <u:%s
       xmlns:u="urn:schemas-upnp-org:service:WANIPConnection:1" />
  </s:Body>
</s:Envelope>""" % (action)

	if self._o_debug:
	    self._debug("""Request to UPnP-Server:
------------------------------------------------------------------------
%s
------------------------------------------------------------------------
""" % (reqBody))

	#    'SOAPACTION'	: "urn:schemas-upnp-org:service:WANIPConnection:1#GetExternalIPAddress"
	mh = {
	    'User-Agent'	: 'pyDNSUpdate/%s' % (__version__),
	    'Content-type'	: 'text/xml; charset="utf-8"',
	    'Content-length'	: len(reqBody),
	    'Connection'	: 'close',
	    'SOAPACTION'	: "urn:schemas-upnp-org:service:WANIPConnection:1#%s" % (action)
	}

	if self._o_debug:
	    self._debug("HTTP Request:")
	    self._debug("\trouter_ip:\t\t%s\n" % (self._router_ip))
	    self._debug("\trouter_port:\t\t%s\n" % (self._router_port))
	    self._debug("\trequest:\t\t%s\n" % (self._router_http_req))

	try:
	    conn = httplib.HTTPConnection(self._router_ip, port=self._router_port)
	    conn.request("POST", self._router_http_req, body=reqBody, headers=mh)
	except:
	    raise
	    sys.exit(1)

	res = conn.getresponse()
	conn.close()

	resBody = ''
	while 1:
	    r = res.read()
	    if '' == r:
		break
	    resBody += r

	if self._o_debug:
	    self._debug("""Answer from UPnP-Server:
------------------------------------------------------------------------
%s
------------------------------------------------------------------------
""" % ( resBody))

	if 200 != res.status:
	    self._error("HTTP request failed: code=%d" % (res.status))
	    sys.exit(1)

	try:
	    xmldoc = minidom.parseString(resBody)
	except:
	    raise
	    sys.exit(1)

	nodelist = xmldoc.getElementsByTagName(result)
	if 0 == len(nodelist):
	    self._error("parsing XML answer: node '%s' not found" % (result))
	    sys.exit(1)

	if self._o_debug:
	    self._debug("found IP address: %s" % (nodelist[0].firstChild.data))
	return(nodelist[0].firstChild.data)

    # ----------------------------------------------------------------
    def dns_delete(self):
	'''send a delete request to the DNS server'''

	keyring = dns.tsigkeyring.from_text({
	    self._dns_keyname : self._dns_keyvalue
	})

	if self._o_debug:
	    self._debug("DNS Update:")
	    self._debug("\tdomain:\t\t%s\n" % (self._dns_domain))
	    self._debug("\thost:\t\t%s\n" % (self._dns_host))
	    self._debug("\tserverip:\t%s\n" % (self._dns_serverip))
	    self._debug("\tkeyname:\t%s\n" % (self._dns_keyname))
	    self._debug("\ttimeout:\t%s\n" % (self._dns_timeout))

	update = dns.update.Update(self._dns_domain, keyring=keyring)
	update.delete(self._dns_host)

	response = dns.query.tcp(update, self._dns_serverip)
	r = dns.rcode.to_text(response.rcode())
	if self._o_debug:
	    self._debug("DNS update rcode: %s\n" % (r))

	if "NOERROR" != r:
	    self._error("error updating DNS record(s): %s" % (r))
	    sys.exit(1)

    # ----------------------------------------------------------------
    def dns_update(self, ipaddress):
	'''send an update request to the DNS server'''

	keyring = dns.tsigkeyring.from_text({
	    self._dns_keyname : self._dns_keyvalue
	})

	tstamp = time.strftime(TFORM_RFC3339, time.localtime())

	if self._o_debug:
	    self._debug("DNS Update:")
	    self._debug("\tdomain:\t\t%s\n" % (self._dns_domain))
	    self._debug("\thost:\t\t%s\n" % (self._dns_host))
	    self._debug("\tserverip:\t%s\n" % (self._dns_serverip))
	    self._debug("\tttl:\t\t%s\n" % (self._dns_ttl))
	    self._debug("\tkeyname:\t%s\n" % (self._dns_keyname))
	    self._debug("\ttimestamp:\t%s\n" % (tstamp))
	    self._debug("\tipaddress:\t%s\n" % (ipaddress))
	    self._debug("\ttimeout:\t%s\n" % (self._dns_timeout))
	    self._debug("\taddtxt:\t\t%s\n" % (self._dns_addtxt))

	update = dns.update.Update(self._dns_domain, keyring=keyring)
	update.replace(self._dns_host, self._dns_ttl, 'A', str(ipaddress))
	if self._dns_addtxt:
	    update.replace(self._dns_host, self._dns_ttl, 'TXT', str(tstamp))

	response = dns.query.tcp(update, self._dns_serverip)
	r = dns.rcode.to_text(response.rcode())
	if self._o_debug:
	    self._debug("DNS update rcode: %s\n" % (r))

	if "NOERROR" != r:
	    self._error("error updating DNS record(s): %s" % (r))
	    sys.exit(1)

# ------------------------------------------------------------------------
if __name__ == "__main__":

    configfile = DEFAULT_CONFIGFILE
    o_delete = False
    o_verbose = False
    o_debug = False
    o_upnp_only = False
    o_help = False
    ipa = None

    try:
        gopts, cmds = getopt.getopt(sys.argv[1:], 'c:dhi:nv', ['help', 'delete'])
    except getopt.GetoptError, e:
	print "Error:", e
	sys.exit(1)

    if cmds:
	print "Error: extraneous parameter(s): %s" % (", ".join(cmds))
	sys.exit(1)

    for o,a in gopts:
        if "-c" == o:
            configfile = a
	elif "-d" == o:
	    o_debug = True
	elif "--delete" == o:
	    o_delete = True
	elif "-h" == o or "--help" == o:
	    o_help = True
	elif "-i" == o:
	    ipa = a
	elif "-n" == o:
	    o_upnp_only = True
	elif "-v" == o:
	    o_verbose = True
	else:
	    print "Huh? %s" % (o)
	    print "Error: internal programming error"
	    sys.exit(1)

    if o_help:
	print """
Usage: %s [ options ]
   options:
	-d	debug; prints some info for trouble shooting
	-h	help; this message
	--help	help; this message
	-n	no dns update; just request the IP from the router
	-v	verbose; outputs the IP address
	--delete
		delete record(s) for the host
	-c cfile
		specifies an alternate configfile
	-i ipaddress
		specifies an IP address to use for dns update
		skips requesting the IP address from the router
""" % (sys.argv[0])
	sys.exit(0)

    dnsu = dnsupdater(configfile=configfile, debug=o_debug)
    if not ipa and not o_delete:
	# get ConnectionStatus to see if the router is connected
    	status = dnsu.upnp_info("GetStatusInfo", "NewConnectionStatus")
	if "Connected" != status:
	    print "Error: ConnectionStatus of router is '%s'" % (status)
	    sys.exit(1)
	# get the external IP address
    	ipa = dnsu.upnp_info("GetExternalIPAddress", "NewExternalIPAddress")

    if o_verbose and not o_delete:
	print "IP-Address: %s" % (ipa)

    if not o_upnp_only:
	if o_delete:
            dnsu.dns_delete()
	else:
            dnsu.dns_update(ipa)

    sys.exit(0)