Simple fake DNS server which returns a single IP address for every query

MiniFakeDNS.py

#!/usr/bin/python -u                                                            
#                                                                               
# MINI FAKE DNS SERVER (PYTHON RECIPE)                                          
# by Francisco Santos  (15 April 2006)                                          
# From http://code.activestate.com/recipes/491264-mini-fake-dns-server/         
# just slightly modified by Eric Myers <myers@spy-hill.net>  7 July 2018        
########################################################################        

# IP address to be returned in response to any query                            
ip='192.168.48.1'

import socket

class DNSQuery:
    def __init__(self, data):
        self.data=data
        ##print("Req: ", data)                                                  
        self.domain=''
        type = (ord(data[2]) >> 3) & 15   # Opcode bits                         
        if type == 0:                     # Standard query                      
            ini=12
            lon= ord(data[ini])
            while lon != 0:
                self.domain += data[ini+1:ini+lon+1]+'.'
                ini += lon+1
                lon = ord(data[ini])

    def response(self, ip):
        packet=''
        if self.domain:
            packet+=self.data[:2] + "\x81\x80"
            # Questions and Answers Counts                                      
            packet+=self.data[4:6] + self.data[4:6] + '\x00\x00\x00\x00'
            packet+=self.data[12:]         # Original Domain Name Question      
            packet+='\xc0\x0c'             # Pointer to domain name             
            # Response type, ttl and resource data length -> 4 bytes            
            packet+='\x00\x01\x00\x01\x00\x00\x00\x3c\x00\x04'
            # 4bytes of IP                                                      
            packet+=str.join('',map(lambda x: chr(int(x)), ip.split('.')))
        return packet

if __name__ == '__main__':
    print('MiniFakeDNS:: dom.query. 60 IN A %s' % ip)

    udps = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    udps.bind(('',53))

    try:
        while 1:
            data, addr = udps.recvfrom(1024)
            p = DNSQuery(data)
            udps.sendto(p.response(ip), addr)
            print( 'Response: %s -> %s' % (p.domain, ip) )
    except KeyboardInterrupt:
        print('MiniFakeDNS done.')
        udps.close()

##