open DNS resolver scanner

#!/usr/bin/env python

import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
from scapy.all import *
import random, threading

def gen_ip():
    try:
        while True:
            yield ".".join([str(random.randint(0,255)) for i in range(4)])
    except KeyboardInterrupt:
        exit()

def check_answer_len(ip):
    packetlen = len(IP(dst=ip)/UDP(dport=53)/DNS(rd=1,qd=DNSQR(qname="mibbit.com", qtype="ALL")))

    answer = sr1(IP(dst=ip)/UDP(dport=53)/DNS(rd=1,qd=DNSQR(qname="mibbit.com", qtype="ALL")),verbose=0, timeout=1)#Mibbit gives good gainz

    try:
        print("Sent packet of size: "+str(packetlen))
        print(str(ip)+" returned reply of length: "+str(len(answer)))
        print("Size increased by "+str(100*(float(len(answer))/float(packetlen)-100))+"%")
        with open("./dnsips","a") as f:
            if len(answer) > packetlen:
                try:
                    f.write(ip+"\t"+str(packetlen)+"->"+str(len(answer))+"\n")
                except:
                    print("erro writn")
        return
    except Exception as e:
        print(str(e))

def server_scan():
    for ip in gen_ip():
        try:
            print(ip)
            resp = sr1(IP(dst=ip)/UDP(dport=53)/DNS(qd=DNSQR(qname="google.com", qtype="A")),timeout=1,verbose=0)
            if not resp:
                continue
            check_answer_len(ip)
        except Exception as e:
            print("Exception: "+str(e))
            break

for i in range(50):
    try:
        threading.Thread(target=server_scan).start()
    except:
        exit()

server_scan()