#!/usr/bin/env python3
# @Time    : 2020-02-23
# @Author  : caicai
# @File    : reverse_dns.py
import time
import struct
import binascii
from myscan.config import reverse_set
from myscan.lib.core.data import logger
from myscan.lib.core.common_reverse import insert_db

try:
    import SocketServer
except:
    import socketserver as SocketServer

ip_address = '127.0.0.1'


def current_time():
    return time.strftime('[%Y.%m.%d %H:%M:%S]', time.localtime())


def decode_dns(dnslog):
    res=""
    try:
        dnslog=dnslog[4:]
        dnslog = dnslog.replace("." + reverse_set.get("reverse_domain"), "")
        dnslog = "".join(dnslog.split("."))
        res=binascii.a2b_hex(dnslog.encode()).decode()
    except binascii.Error as ex:
        pass
    except Exception as ex:
        logger.warning('decode dns get error:{}'.format(ex))
    return res


class SinDNSQuery:
    def __init__(self, data):
        i = 1
        self.name = ''
        while True:
            try:
                d = ord(data[i])
            except:
                d = data[i]
            if d == 0:
                break
            if d < 32:
                self.name += '.'
            else:
                self.name += chr(d)
            i += 1
        self.querybytes = data[0:i + 1]
        self.type, self.classify = struct.unpack('>HH', data[i + 1:i + 5])
        self.len = i + 5

    def getbytes(self):
        return self.querybytes + struct.pack('>HH', self.type, self.classify)


class SinDNSAnswer:
    def __init__(self, ip):
        self.type = 1
        self.classify = 1
        self.name = 49164
        self.datalength = 4
        self.timetolive = 190
        self.ip = ip

    def getbytes(self):
        res = struct.pack('>HHHLH', self.name, self.type, self.classify, self.timetolive, self.datalength)
        s = self.ip.split('.')
        res += struct.pack('BBBB', int(s[0]), int(s[1]), int(s[2]), int(s[3]))
        return res


class SinDNSFrame:
    def __init__(self, data):
        (self.id, self.flags, self.quests, self.answers, self.author, self.addition) = struct.unpack('>HHHHHH',
                                                                                                     data[0:12])
        self.query = SinDNSQuery(data[12:])

    def getname(self):
        return self.query.name

    def setip(self, ip):
        self.answer = SinDNSAnswer(ip)
        self.answers = 1
        self.flags = 33152

    def getbytes(self):
        res = struct.pack('>HHHHHH', self.id, self.flags, self.quests, self.answers, self.author, self.addition)
        res = res + self.query.getbytes()
        if self.answers != 0:
            res += self.answer.getbytes()
        return res


class DnsRequestHandler(SocketServer.BaseRequestHandler):
    def handle(self):
        data = self.request[0].strip()
        dns = SinDNSFrame(data)
        conn = self.request[1]
        query_name = dns.getname()
        # A record
        if dns.query.type == 1:
            response = ip_address if query_name.endswith(reverse_set.get("reverse_domain")) else None
            if response:
                dns.setip(response)
                log_format = {'client_ip': self.client_address[0], 'client_port': self.client_address[1],
                              'query': query_name, 'record-type': 'A', 'response': response}
                conn.sendto(dns.getbytes(), self.client_address)
                res = {}
                res["type"] = "dns"
                res["client"] = self.client_address[0]
                res["query"] = query_name
                res["info"] = decode_dns(query_name)
                res["time"] = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(time.time()))
                logger.info("Insert to db:" + str(res))
                insert_db(res)


        # # AAAA record
        # elif dns.query.type == 28:
        #     response = ip_address if query_name.endswith(reverse_set.get("reverse_domain")) else None
        #     if response:
        #         dns.setip(response)
        #         conn.sendto(dns.getbytes(), self.client_address)
        #         log_format = {'client_ip': self.client_address[0], 'client_port': self.client_address[1],
        #                       'query': query_name, 'record-type': 'AAAA', 'response': response}
        #         res = {}
        #         res["type"] = "dns"
        #         res["client"] = self.client_address[0]
        #         res["query"] = query_name
        #         res["info"] = ""
        #         res["time"] = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(time.time()))
        #         logger.info(str(res))
        else:
            dns.setip(ip_address)
            conn.sendto(dns.getbytes(), self.client_address)


class SimpleDnsServer:
    def __init__(self, port=53):
        self.port = port

    def start(self):
        host, port = "0.0.0.0", self.port
        dns_udp_server = SocketServer.UDPServer((host, port), DnsRequestHandler)
        dns_udp_server.serve_forever()


def dns_start():
    dns_server = SimpleDnsServer()
    dns_server.start()
