Anti gfw6's dns pollution

block_bad_ip.py

#!/usr/bin/env python2
# -*- coding:utf-8 -*-

import os
import sys

def ip62hex(ip):
    ip = map(lambda x: int(x, 16), ip.split(':'))
    hexed = reduce(list.__add__,
                    [[(x >> 8), (x & 0x00FF)] for x in ip])
    hexed = map(lambda x: "%02X" % x, hexed)
    return hexed

def natural2hex(ip):
    if ip.find(':') >= 0:
        # AAAA
        ip = ip.split('::')
        if len(ip) == 1:
            hexed_ip = ' '.join(ip62hex(ip[0]))

        else:
            head, tail = map(ip62hex, ip)
            nzero = 16 - len(head) - len(tail)
            zeros = ['00' for x in range(nzero)]
            hexed_ip = ' '.join(head + zeros + tail)
    elif ip.find('.') >= 0:
        ip_tuple = ip.split('.')
        hexed_ip = ' '.join(map(lambda x: "%02X" % int(x), ip_tuple))
    return hexed_ip

def block_ip(hexed_ip):
    print "blocked", hexed_ip
    cmd = "ip6tables -A INPUT -p udp --sport 53 -s 2001:470:20::2 -m string --algo bm --hex-string \"|%s|\" --from 60 --to 180 -j DROP" % hexed_ip
    os.system(cmd)

def main():
    if len(sys.argv) == 1:
        for line in sys.stdin.readlines():
            hexed_ip = line.strip()
            block_ip(hexed_ip)
    else:
        ip = sys.argv[1]
        hexed_ip = natural2hex(ip)
        block_ip(hexed_ip)

if __name__=="__main__":
    main()

# vim: ts=4 sw=4 sts=4 expandtab

touch-agent.py

#!/usr/bin/env python2
# -*- coding:utf-8 -*-
import dnslib
import socket

def init_socket():
    HOST = "2001:470:20::2"
    PORT = 53
    for res in socket.getaddrinfo(HOST, PORT, socket.AF_INET6, socket.SOCK_DGRAM):
        af, socktype, proto, canonname, sa = res
        try:
            s = socket.socket(af, socktype, proto)
        except socket.error:
            s = None
            continue
        try:
            s.connect(sa)
        except socket.error:
            s.close()
            s = None
            continue
        break
    return s


def touch_gfw():
    HOST = "www.youtube.com"
    query = dnslib.DNSRecord(q=dnslib.DNSQuestion(HOST, dnslib.QTYPE.AAAA))

    s = init_socket()
    if s is None:
        raise
    s.settimeout(5)
    s.send(query.pack())

    answer_packets = []

    while 1:
        try:
            a, t = s.recvfrom(65535)
        except socket.timeout:
            break
        answer_packets.append(a)

    answer_packets.pop()

    for answer in answer_packets:
        d = dnslib.DNSRecord.parse(answer)
        bad_ip = d.a.rdata.data
        print ' '.join(map(lambda x: "%02X" % x, bad_ip))

if __name__=="__main__":
    touch_gfw()

# vim: ts=4 sw=4 sts=4 expandtab