DNS compression pointer mutation

00-README.txt

$ LD_PRELOAD=$PWD/sendmsg.so dig twitter.com @8.8.8.8
;; Warning: Message parser reports malformed message packet. <-- malformed 因为把压缩指针当作域名一部分了
;; Question section mismatch: got twitter.com/RESERVED0/CLASS256

; <<>> DiG 9.9.5-3-Ubuntu <<>> twitter.com @8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44722
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;twitter.com.                   IN      A

;; ANSWER SECTION:
twitter.com.            12      IN      A       199.59.150.7
twitter.com.            12      IN      A       199.59.148.82
twitter.com.            12      IN      A       199.59.149.198
twitter.com.            12      IN      A       199.59.149.230

;; Query time: 400 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Nov 15 -------- CST 2014
;; MSG SIZE  rcvd: 104

$ LD_PRELOAD=$PWD/sendmsg.so host twitter.com 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases: 

twitter.com has address 199.59.148.82
twitter.com has address 199.59.149.230
twitter.com has address 199.59.149.198
twitter.com has address 199.59.148.10
twitter.com mail is handled by 30 ASPMX2.GOOGLEMAIL.com.
twitter.com mail is handled by 10 aspmx.l.google.com.
twitter.com mail is handled by 20 alt2.aspmx.l.google.com.
twitter.com mail is handled by 20 alt1.aspmx.l.google.com.
twitter.com mail is handled by 30 ASPMX3.GOOGLEMAIL.com.
$ host twitter.com 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases: 

twitter.com has address 59.24.3.173
twitter.com has address 59.24.3.173
twitter.com has address 37.61.54.158

CHINA-to-US-results.txt

example.com normal google-dns1 NOERROR example.com. 20087 IN A 93.184.216.119
example.com normal google-dns2 NOERROR example.com. 20098 IN A 93.184.216.119
example.com normal opendns1 NOERROR example.com. 68574 IN A 93.184.216.119
example.com normal opendns2 NOERROR example.com. 74046 IN A 93.184.216.119
example.com normal twitter-ns1 NOERROR 
example.com normal twitter-ns2 NOERROR 
example.com normal he-dns NOERROR example.com. 86160 IN A 93.184.216.119
example.com normal level3 NOERROR example.com. 86400 IN A 93.184.216.119
example.com normal alidns1 NOERROR example.com. 57929 IN A 93.184.216.119
example.com normal alidns2 NOERROR example.com. 32633 IN A 93.184.216.119
example.com normal cnnic-dns1 NOERROR example.com. 84765 IN A 93.184.216.119
example.com normal v2ex-dns1 NOERROR example.com. 4074 IN A 93.184.216.119
example.com normal unicom-sh1 NOERROR example.com. 60682 IN A 93.184.216.119
example.com normal unicom-sh2 NOERROR example.com. 79776 IN A 93.184.216.119
example.com normal china-blackhole-1 
example.com normal china-blackhole-2 
example.com normal china-blackhole-3 
example.com normal china-blackhole-4 
twitter.com normal google-dns1 NOERROR twitter.com. 37569 IN A 37.61.54.158
twitter.com normal google-dns2 NOERROR twitter.com. 41492 IN A 59.24.3.173
twitter.com normal opendns1 NOERROR twitter.com. 13193 IN A 59.24.3.173
twitter.com normal opendns2 NOERROR twitter.com. 8768 IN A 37.61.54.158
twitter.com normal twitter-ns1 NOERROR twitter.com. 33232 IN A 37.61.54.158
twitter.com normal twitter-ns2 NOERROR twitter.com. 30 IN A 199.59.150.7 twitter.com. 30 IN A 199.59.148.10 twitter.com. 30 IN A 199.59.149.230 twitter.com. 30 IN A 199.59.150.39
twitter.com normal he-dns NOERROR twitter.com. 41492 IN A 59.24.3.173
twitter.com normal level3 NOERROR twitter.com. 30851 IN A 37.61.54.158
twitter.com normal alidns1 NOERROR twitter.com. 38987 IN A 59.24.3.173
twitter.com normal alidns2 NOERROR twitter.com. 38987 IN A 59.24.3.173
twitter.com normal cnnic-dns1 NOERROR twitter.com. 23292 IN A 37.61.54.158
twitter.com normal v2ex-dns1 NOERROR twitter.com. 31559 IN A 59.24.3.173
twitter.com normal unicom-sh1 NOERROR twitter.com. 19662 IN A 59.24.3.173
twitter.com normal unicom-sh2 NOERROR twitter.com. 246 IN A 37.61.54.158
twitter.com normal china-blackhole-1 
twitter.com normal china-blackhole-2 
twitter.com normal china-blackhole-3 
twitter.com normal china-blackhole-4 
example.com pointer-0 google-dns1 NOERROR example.com. 20069 IN A 93.184.216.119
example.com pointer-0 google-dns2 NOERROR example.com. 20079 IN A 93.184.216.119
example.com pointer-0 opendns1 NOERROR example.com. 68555 IN A 93.184.216.119
example.com pointer-0 opendns2 NOERROR example.com. 74027 IN A 93.184.216.119
example.com pointer-0 twitter-ns1 
example.com pointer-0 twitter-ns2 
example.com pointer-0 he-dns FORMERR 
example.com pointer-0 level3 FORMERR 
example.com pointer-0 alidns1 
example.com pointer-0 alidns2 
example.com pointer-0 cnnic-dns1 
example.com pointer-0 v2ex-dns1 NOERROR example.com. 4045 IN A 93.184.216.119
example.com pointer-0 unicom-sh1 REFUSED 
example.com pointer-0 unicom-sh2 
example.com pointer-0 china-blackhole-1 
example.com pointer-0 china-blackhole-2 
example.com pointer-0 china-blackhole-3 
example.com pointer-0 china-blackhole-4 
twitter.com pointer-0 google-dns1 NOERROR twitter.com. 21546 IN A 59.24.3.173
twitter.com pointer-0 google-dns2 NOERROR twitter.com. 9482 IN A 59.24.3.173
twitter.com pointer-0 opendns1 NOERROR twitter.com. 8377 IN A 59.24.3.173
twitter.com pointer-0 opendns2 NOERROR twitter.com. 21546 IN A 59.24.3.173
twitter.com pointer-0 twitter-ns1 NOERROR twitter.com. 21546 IN A 59.24.3.173
twitter.com pointer-0 twitter-ns2 NOERROR twitter.com. 21546 IN A 59.24.3.173
twitter.com pointer-0 he-dns NOERROR twitter.com. 21546 IN A 59.24.3.173
twitter.com pointer-0 level3 NOERROR twitter.com. 21546 IN A 59.24.3.173
twitter.com pointer-0 alidns1 
twitter.com pointer-0 alidns2 
twitter.com pointer-0 cnnic-dns1 
twitter.com pointer-0 v2ex-dns1 NOERROR twitter.com. 4493 IN A 59.24.3.173
twitter.com pointer-0 unicom-sh1 REFUSED 
twitter.com pointer-0 unicom-sh2 
twitter.com pointer-0 china-blackhole-1 
twitter.com pointer-0 china-blackhole-2 
twitter.com pointer-0 china-blackhole-3 
twitter.com pointer-0 china-blackhole-4 
example.com pointer-1 google-dns1 NOERROR example.com. 20035 IN A 93.184.216.119
example.com pointer-1 google-dns2 NOERROR example.com. 20041 IN A 93.184.216.119
example.com pointer-1 opendns1 NOERROR example.com. 74071 IN A 93.184.216.119
example.com pointer-1 opendns2 NOERROR example.com. 74070 IN A 93.184.216.119
example.com pointer-1 twitter-ns1 
example.com pointer-1 twitter-ns2 
example.com pointer-1 he-dns FORMERR 
example.com pointer-1 level3 FORMERR 
example.com pointer-1 alidns1 
example.com pointer-1 alidns2 
example.com pointer-1 cnnic-dns1 
example.com pointer-1 v2ex-dns1 NOERROR example.com. 4007 IN A 93.184.216.119
example.com pointer-1 unicom-sh1 REFUSED 
example.com pointer-1 unicom-sh2 
example.com pointer-1 china-blackhole-1 
example.com pointer-1 china-blackhole-2 
example.com pointer-1 china-blackhole-3 
example.com pointer-1 china-blackhole-4 
twitter.com pointer-1 google-dns1 NOERROR twitter.com. 27 IN A 199.59.149.230 twitter.com. 27 IN A 199.59.148.82 twitter.com. 27 IN A 199.59.150.39 twitter.com. 27 IN A 199.59.148.10
twitter.com pointer-1 google-dns2 NOERROR twitter.com. 27 IN A 199.59.149.198 twitter.com. 27 IN A 199.59.149.230 twitter.com. 27 IN A 199.59.150.39 twitter.com. 27 IN A 199.59.148.10
twitter.com pointer-1 opendns1 NOERROR twitter.com. 19 IN A 199.59.149.198 twitter.com. 19 IN A 199.59.150.7 twitter.com. 19 IN A 199.59.149.230 twitter.com. 19 IN A 199.59.148.82
twitter.com pointer-1 opendns2 NOERROR twitter.com. 19 IN A 199.59.148.82 twitter.com. 19 IN A 199.59.150.39 twitter.com. 19 IN A 199.59.150.7 twitter.com. 19 IN A 199.59.149.230
twitter.com pointer-1 twitter-ns1 
twitter.com pointer-1 twitter-ns2 
twitter.com pointer-1 he-dns FORMERR 
twitter.com pointer-1 level3 FORMERR 
twitter.com pointer-1 alidns1 
twitter.com pointer-1 alidns2 
twitter.com pointer-1 cnnic-dns1 
twitter.com pointer-1 v2ex-dns1 NOERROR twitter.com. 19 IN A 199.59.150.7 twitter.com. 19 IN A 199.59.148.10 twitter.com. 19 IN A 199.59.148.82 twitter.com. 19 IN A 199.59.150.39
twitter.com pointer-1 unicom-sh1 REFUSED 
twitter.com pointer-1 unicom-sh2 
twitter.com pointer-1 china-blackhole-1 
twitter.com pointer-1 china-blackhole-2 
twitter.com pointer-1 china-blackhole-3 
twitter.com pointer-1 china-blackhole-4 
example.com pointer-4 google-dns1 NOERROR example.com. 20004 IN A 93.184.216.119
example.com pointer-4 google-dns2 NOERROR example.com. 19989 IN A 93.184.216.119
example.com pointer-4 opendns1 NOERROR example.com. 73946 IN A 93.184.216.119
example.com pointer-4 opendns2 NOERROR example.com. 68474 IN A 93.184.216.119
example.com pointer-4 twitter-ns1 
example.com pointer-4 twitter-ns2 
example.com pointer-4 he-dns FORMERR 
example.com pointer-4 level3 FORMERR 
example.com pointer-4 alidns1 
example.com pointer-4 alidns2 
example.com pointer-4 cnnic-dns1 
example.com pointer-4 v2ex-dns1 NOERROR example.com. 3964 IN A 93.184.216.119
example.com pointer-4 unicom-sh1 REFUSED 
example.com pointer-4 unicom-sh2 
example.com pointer-4 china-blackhole-1 
example.com pointer-4 china-blackhole-2 
example.com pointer-4 china-blackhole-3 
example.com pointer-4 china-blackhole-4 
twitter.com pointer-4 google-dns1 NOERROR twitter.com. 14 IN A 199.59.149.198 twitter.com. 14 IN A 199.59.148.10 twitter.com. 14 IN A 199.59.150.39 twitter.com. 14 IN A 199.59.149.230
twitter.com pointer-4 google-dns2 NOERROR twitter.com. 13 IN A 199.59.150.39 twitter.com. 13 IN A 199.59.148.10 twitter.com. 13 IN A 199.59.149.230 twitter.com. 13 IN A 199.59.150.7
twitter.com pointer-4 opendns1 NOERROR twitter.com. 30 IN A 199.59.150.39 twitter.com. 30 IN A 199.59.148.10 twitter.com. 30 IN A 199.59.148.82 twitter.com. 30 IN A 199.59.149.198
twitter.com pointer-4 opendns2 NOERROR twitter.com. 29 IN A 199.59.148.82 twitter.com. 29 IN A 199.59.150.39 twitter.com. 29 IN A 199.59.150.7 twitter.com. 29 IN A 199.59.149.198
twitter.com pointer-4 twitter-ns1 
twitter.com pointer-4 twitter-ns2 
twitter.com pointer-4 he-dns FORMERR 
twitter.com pointer-4 level3 FORMERR 
twitter.com pointer-4 alidns1 
twitter.com pointer-4 alidns2 
twitter.com pointer-4 cnnic-dns1 
twitter.com pointer-4 v2ex-dns1 NOERROR twitter.com. 4 IN A 199.59.148.82 twitter.com. 4 IN A 199.59.148.10 twitter.com. 4 IN A 199.59.150.7 twitter.com. 4 IN A 199.59.149.198
twitter.com pointer-4 unicom-sh1 REFUSED 
twitter.com pointer-4 unicom-sh2 
twitter.com pointer-4 china-blackhole-1 
twitter.com pointer-4 china-blackhole-2 
twitter.com pointer-4 china-blackhole-3 
twitter.com pointer-4 china-blackhole-4 
example.com pointer-append google-dns1 NOERROR example.com. 19947 IN A 93.184.216.119
example.com pointer-append google-dns2 NOERROR example.com. 19946 IN A 93.184.216.119
example.com pointer-append opendns1 FORMERR 
example.com pointer-append opendns2 FORMERR 
example.com pointer-append twitter-ns1 
example.com pointer-append twitter-ns2 
example.com pointer-append he-dns parse error
example.com pointer-append level3 parse error
example.com pointer-append alidns1 
example.com pointer-append alidns2 
example.com pointer-append cnnic-dns1 
example.com pointer-append v2ex-dns1 NOERROR example.com. 3921 IN A 93.184.216.119
example.com pointer-append unicom-sh1 FORMERR 
example.com pointer-append unicom-sh2 FORMERR 
example.com pointer-append china-blackhole-1 
example.com pointer-append china-blackhole-2 
example.com pointer-append china-blackhole-3 
example.com pointer-append china-blackhole-4 
twitter.com pointer-append google-dns1 NOERROR twitter.com. 29 IN A 199.59.148.10 twitter.com. 29 IN A 199.59.149.230 twitter.com. 29 IN A 199.59.148.82 twitter.com. 29 IN A 199.59.149.198
twitter.com pointer-append google-dns2 NOERROR twitter.com. 28 IN A 199.59.150.39 twitter.com. 28 IN A 199.59.149.230 twitter.com. 28 IN A 199.59.148.82 twitter.com. 28 IN A 199.59.149.198
twitter.com pointer-append opendns1 FORMERR 
twitter.com pointer-append opendns2 FORMERR 
twitter.com pointer-append twitter-ns1 
twitter.com pointer-append twitter-ns2 
twitter.com pointer-append he-dns parse error
twitter.com pointer-append level3 parse error
twitter.com pointer-append alidns1 
twitter.com pointer-append alidns2 
twitter.com pointer-append cnnic-dns1 
twitter.com pointer-append v2ex-dns1 NOERROR twitter.com. 22 IN A 199.59.148.10 twitter.com. 22 IN A 199.59.149.198 twitter.com. 22 IN A 199.59.150.39 twitter.com. 22 IN A 199.59.149.230
twitter.com pointer-append unicom-sh1 FORMERR 
twitter.com pointer-append unicom-sh2 FORMERR 
twitter.com pointer-append china-blackhole-1 
twitter.com pointer-append china-blackhole-2 
twitter.com pointer-append china-blackhole-3 
twitter.com pointer-append china-blackhole-4 
example.com pointer-append-rr google-dns1 NOERROR example.com. 19923 IN A 93.184.216.119
example.com pointer-append-rr google-dns2 NOERROR example.com. 19915 IN A 93.184.216.119
example.com pointer-append-rr opendns1 FORMERR 
example.com pointer-append-rr opendns2 FORMERR 
example.com pointer-append-rr twitter-ns1 
example.com pointer-append-rr twitter-ns2 
example.com pointer-append-rr he-dns parse error
example.com pointer-append-rr level3 parse error
example.com pointer-append-rr alidns1 
example.com pointer-append-rr alidns2 
example.com pointer-append-rr cnnic-dns1 
example.com pointer-append-rr v2ex-dns1 NOERROR example.com. 3881 IN A 93.184.216.119
example.com pointer-append-rr unicom-sh1 FORMERR 
example.com pointer-append-rr unicom-sh2 FORMERR 
example.com pointer-append-rr china-blackhole-1 
example.com pointer-append-rr china-blackhole-2 
example.com pointer-append-rr china-blackhole-3 
example.com pointer-append-rr china-blackhole-4 
twitter.com pointer-append-rr google-dns1 NOERROR twitter.com. 21 IN A 199.59.148.10 twitter.com. 21 IN A 199.59.150.39 twitter.com. 21 IN A 199.59.148.82 twitter.com. 21 IN A 199.59.149.230
twitter.com pointer-append-rr google-dns2 NOERROR twitter.com. 20 IN A 199.59.149.230 twitter.com. 20 IN A 199.59.150.7 twitter.com. 20 IN A 199.59.150.39 twitter.com. 20 IN A 199.59.148.82
twitter.com pointer-append-rr opendns1 FORMERR 
twitter.com pointer-append-rr opendns2 FORMERR 
twitter.com pointer-append-rr twitter-ns1 
twitter.com pointer-append-rr twitter-ns2 
twitter.com pointer-append-rr he-dns parse error
twitter.com pointer-append-rr level3 parse error
twitter.com pointer-append-rr alidns1 
twitter.com pointer-append-rr alidns2 
twitter.com pointer-append-rr cnnic-dns1 
twitter.com pointer-append-rr v2ex-dns1 NOERROR twitter.com. 9 IN A 199.59.150.39 twitter.com. 9 IN A 199.59.148.82 twitter.com. 9 IN A 199.59.148.10 twitter.com. 9 IN A 199.59.150.7
twitter.com pointer-append-rr unicom-sh1 FORMERR 
twitter.com pointer-append-rr unicom-sh2 FORMERR 
twitter.com pointer-append-rr china-blackhole-1 
twitter.com pointer-append-rr china-blackhole-2 
twitter.com pointer-append-rr china-blackhole-3 
twitter.com pointer-append-rr china-blackhole-4 

sendmsg.c

/*
  gcc -fPIC -shared sendmsg.c -o sendmsg.so -ldl
  LD_PRELOAD=$PWD/sendmsg.so host twitter.com 8.8.8.8
  LD_PRELOAD=$PWD/sendmsg.so dig twitter.com @8.8.8.8
*/
#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

static ssize_t (*_sendmsg)(int, const struct msghdr *, int);

ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags)
{
	if (!_sendmsg) {
		_sendmsg = dlsym(RTLD_NEXT, "sendmsg");
		if (!_sendmsg) {
			perror("dlsym");
			exit(1);
		}
	}

	struct msghdr newmsg;
	char buffer[512];
	struct iovec vec;
	if (msg->msg_namelen == sizeof(struct sockaddr_in) && msg->msg_iovlen == 1) {
		const struct sockaddr_in *addr = (const struct sockaddr_in *)msg->msg_name;
		const unsigned char *bytes = msg->msg_iov[0].iov_base;
		const unsigned short *shorts = msg->msg_iov[0].iov_base;
		size_t len = msg->msg_iov[0].iov_len;
		if (addr->sin_family == AF_INET && addr->sin_port == htons(53) &&
		len < sizeof(buffer) - 1 && len > 16 && shorts[2] == htons(1) && shorts[3] == 0) {
			size_t off = 12;
			int ended = 0;
			while (off < len - 4) {
				if (bytes[off] & 0xc0)
					break;
				if (bytes[off] == 0) {
					ended = 1;
					off++;
					break;
				}
				off += 1 + bytes[off];
			}
			if (ended) {
				memcpy(buffer, bytes, off - 1);
				memcpy(buffer + off + 1, bytes + off, len - off);
				buffer[off - 1] = '\xc0';
				buffer[off] = '\x04';

				vec.iov_base = buffer;
				vec.iov_len = len + 1;

				newmsg = *msg;
				newmsg.msg_iov = &vec;
				msg = &newmsg;
			}
		}
	}

	return _sendmsg(sockfd, msg, flags);
}

test.py

import socket
import dns.message, dns.rcode

queries = [
('example.com normal', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07example\x03com\x00\x00\x01\x00\x01"),
('twitter.com normal', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07twitter\x03com\x00\x00\x01\x00\x01"),
('example.com pointer-0', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07example\x03com\xc0\x00\x00\x01\x00\x01"),
('twitter.com pointer-0', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07twitter\x03com\xc0\x00\x00\x01\x00\x01"),
('example.com pointer-1', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07example\x03com\xc0\x01\x00\x01\x00\x01"),
('twitter.com pointer-1', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07twitter\x03com\xc0\x01\x00\x01\x00\x01"),
('example.com pointer-4', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07example\x03com\xc0\x04\x00\x01\x00\x01"),
('twitter.com pointer-4', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x07twitter\x03com\xc0\x04\x00\x01\x00\x01"),
('example.com pointer-append', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\xc0\x12\x00\x01\x00\x01\x07example\x03com\x00"),
('twitter.com pointer-append', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\xc0\x12\x00\x01\x00\x01\x07twitter\x03com\x00"),
('example.com pointer-append-rr', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x01\xc0\x12\x00\x01\x00\x01\x07example\x03com\x00\x00\x01\x00\x01\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00"),
('twitter.com pointer-append-rr', "\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x01\xc0\x12\x00\x01\x00\x01\x07twitter\x03com\x00\x00\x01\x00\x01\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00"),
]

resolvers = [
('google-dns1', '8.8.8.8'),
('google-dns2', '8.8.4.4'),
('opendns1', '208.67.222.222'),
('opendns2', '208.67.220.220'),
('twitter-ns1', '208.78.70.34'),
('twitter-ns2', '204.13.250.34'),
('he-dns', '74.82.42.42'),
('level3', '4.2.2.2'),
('alidns1', '223.5.5.5'),
('alidns2', '223.6.6.6'),
('cnnic-dns1', '1.2.4.8'),
('v2ex-dns1', '199.91.73.222'),
('unicom-sh1', '210.22.70.3'),
('unicom-sh2', '210.22.84.3'),
('china-blackhole-1', '210.22.0.0'),
('china-blackhole-2', '210.21.0.0'),
('china-blackhole-3', '202.96.0.0'),
('china-blackhole-4', '116.228.0.0'),
]

def test_query(resolver, query):
	sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
	sock.settimeout(0.1)
	result = ''
	for i in range(20):
		sock.sendto(query, (resolver, 53))
		try:
			packet, addr = sock.recvfrom(2048)
			try:
				r = dns.message.from_wire(packet)
				rc = dns.rcode.from_flags(r.flags, r.ednsflags)
				result = dns.rcode.to_text(rc) + ' ' + ' '.join(str(rr) for rr in r.answer).replace('\n', ' ')
			except:
				result = 'parse error'
			break
		except socket.timeout:
			pass
	sock.close()
	return result

for qname, query in queries:
	for rname, resolver in resolvers:
		print qname, rname, test_query(resolver, query)

US-to-CHINA-results.txt

example.com normal google-dns1 NOERROR example.com. 4268 IN A 93.184.216.119
example.com normal google-dns2 NOERROR example.com. 4268 IN A 93.184.216.119
example.com normal opendns1 NOERROR example.com. 27992 IN A 93.184.216.119
example.com normal opendns2 NOERROR example.com. 27992 IN A 93.184.216.119
example.com normal twitter-ns1 NOERROR 
example.com normal twitter-ns2 NOERROR 
example.com normal he-dns NOERROR example.com. 86278 IN A 93.184.216.119
example.com normal level3 NOERROR example.com. 69051 IN A 93.184.216.119
example.com normal alidns1 NOERROR example.com. 73901 IN A 93.184.216.119
example.com normal alidns2 NOERROR example.com. 73900 IN A 93.184.216.119
example.com normal cnnic-dns1 NOERROR example.com. 61965 IN A 93.184.216.119
example.com normal v2ex-dns1 NOERROR example.com. 14652 IN A 93.184.216.119
example.com normal unicom-sh1 NOERROR example.com. 84929 IN A 93.184.216.119
example.com normal unicom-sh2 NOERROR example.com. 80503 IN A 93.184.216.119
example.com normal china-blackhole-1 
example.com normal china-blackhole-2 
example.com normal china-blackhole-3 
example.com normal china-blackhole-4 
twitter.com normal google-dns1 NOERROR twitter.com. 29 IN A 199.16.156.230 twitter.com. 29 IN A 199.16.156.38 twitter.com. 29 IN A 199.16.156.70 twitter.com. 29 IN A 199.16.156.102
twitter.com normal google-dns2 NOERROR twitter.com. 29 IN A 199.16.156.230 twitter.com. 29 IN A 199.16.156.38 twitter.com. 29 IN A 199.16.156.70 twitter.com. 29 IN A 199.16.156.102
twitter.com normal opendns1 NOERROR twitter.com. 26 IN A 199.16.156.102 twitter.com. 26 IN A 199.16.156.198 twitter.com. 26 IN A 199.16.156.38 twitter.com. 26 IN A 199.16.156.70
twitter.com normal opendns2 NOERROR twitter.com. 19 IN A 199.16.156.198 twitter.com. 19 IN A 199.16.156.6 twitter.com. 19 IN A 199.16.156.38 twitter.com. 19 IN A 199.16.156.230
twitter.com normal twitter-ns1 NOERROR twitter.com. 30 IN A 199.16.156.38 twitter.com. 30 IN A 199.16.156.70 twitter.com. 30 IN A 199.16.156.6 twitter.com. 30 IN A 199.16.156.198
twitter.com normal twitter-ns2 NOERROR twitter.com. 30 IN A 199.16.156.6 twitter.com. 30 IN A 199.16.156.102 twitter.com. 30 IN A 199.16.156.38 twitter.com. 30 IN A 199.16.156.198
twitter.com normal he-dns NOERROR twitter.com. 18 IN A 199.59.149.198 twitter.com. 18 IN A 199.59.150.39 twitter.com. 18 IN A 199.59.150.7 twitter.com. 18 IN A 199.59.149.230
twitter.com normal level3 NOERROR twitter.com. 63 IN A 199.16.156.38 twitter.com. 63 IN A 199.16.156.70 twitter.com. 63 IN A 199.16.156.230 twitter.com. 63 IN A 199.16.156.6
twitter.com normal alidns1 NOERROR twitter.com. 25877 IN A 37.61.54.158
twitter.com normal alidns2 NOERROR twitter.com. 9962 IN A 37.61.54.158
twitter.com normal cnnic-dns1 NOERROR twitter.com. 30 IN A 199.59.149.198 twitter.com. 30 IN A 199.59.150.7 twitter.com. 30 IN A 199.59.148.82 twitter.com. 30 IN A 199.59.150.39
twitter.com normal v2ex-dns1 NOERROR twitter.com. 27 IN A 199.59.149.198 twitter.com. 27 IN A 199.59.148.82 twitter.com. 27 IN A 199.59.150.39 twitter.com. 27 IN A 199.59.150.7
twitter.com normal unicom-sh1 NOERROR twitter.com. 9340 IN A 37.61.54.158
twitter.com normal unicom-sh2 NOERROR twitter.com. 43022 IN A 37.61.54.158
twitter.com normal china-blackhole-1 NOERROR twitter.com. 44055 IN A 59.24.3.173
twitter.com normal china-blackhole-2 NOERROR twitter.com. 42928 IN A 37.61.54.158
twitter.com normal china-blackhole-3 NOERROR twitter.com. 17089 IN A 37.61.54.158
twitter.com normal china-blackhole-4 NOERROR twitter.com. 41669 IN A 37.61.54.158
example.com pointer-0 google-dns1 NOERROR example.com. 4254 IN A 93.184.216.119
example.com pointer-0 google-dns2 NOERROR example.com. 4254 IN A 93.184.216.119
example.com pointer-0 opendns1 NOERROR example.com. 25344 IN A 93.184.216.119
example.com pointer-0 opendns2 NOERROR example.com. 31465 IN A 93.184.216.119
example.com pointer-0 twitter-ns1 
example.com pointer-0 twitter-ns2 
example.com pointer-0 he-dns FORMERR 
example.com pointer-0 level3 NOERROR example.com. 69033 IN A 93.184.216.119
example.com pointer-0 alidns1 
example.com pointer-0 alidns2 
example.com pointer-0 cnnic-dns1 
example.com pointer-0 v2ex-dns1 NOERROR example.com. 14629 IN A 93.184.216.119
example.com pointer-0 unicom-sh1 REFUSED 
example.com pointer-0 unicom-sh2 
example.com pointer-0 china-blackhole-1 
example.com pointer-0 china-blackhole-2 
example.com pointer-0 china-blackhole-3 
example.com pointer-0 china-blackhole-4 
twitter.com pointer-0 google-dns1 NOERROR twitter.com. 4 IN A 199.16.156.6 twitter.com. 4 IN A 199.16.156.70 twitter.com. 4 IN A 199.16.156.230 twitter.com. 4 IN A 199.16.156.198
twitter.com pointer-0 google-dns2 NOERROR twitter.com. 4 IN A 199.16.156.102 twitter.com. 4 IN A 199.16.156.70 twitter.com. 4 IN A 199.16.156.6 twitter.com. 4 IN A 199.16.156.38
twitter.com pointer-0 opendns1 NOERROR twitter.com. 29 IN A 199.16.156.198 twitter.com. 29 IN A 199.16.156.230 twitter.com. 29 IN A 199.16.156.6 twitter.com. 29 IN A 199.16.156.38
twitter.com pointer-0 opendns2 NOERROR twitter.com. 21 IN A 199.16.156.198 twitter.com. 21 IN A 199.16.156.38 twitter.com. 21 IN A 199.16.156.6 twitter.com. 21 IN A 199.16.156.230
twitter.com pointer-0 twitter-ns1 
twitter.com pointer-0 twitter-ns2 
twitter.com pointer-0 he-dns FORMERR 
twitter.com pointer-0 level3 FORMERR 
twitter.com pointer-0 alidns1 NOERROR twitter.com. 38584 IN A 59.24.3.173
twitter.com pointer-0 alidns2 NOERROR twitter.com. 46742 IN A 59.24.3.173
twitter.com pointer-0 cnnic-dns1 
twitter.com pointer-0 v2ex-dns1 NOERROR twitter.com. 26 IN A 199.59.149.198 twitter.com. 26 IN A 199.59.150.39 twitter.com. 26 IN A 199.59.148.82 twitter.com. 26 IN A 199.59.149.230
twitter.com pointer-0 unicom-sh1 NOERROR twitter.com. 31863 IN A 59.24.3.173
twitter.com pointer-0 unicom-sh2 NOERROR twitter.com. 31863 IN A 59.24.3.173
twitter.com pointer-0 china-blackhole-1 NOERROR twitter.com. 31919 IN A 59.24.3.173
twitter.com pointer-0 china-blackhole-2 NOERROR twitter.com. 31919 IN A 59.24.3.173
twitter.com pointer-0 china-blackhole-3 NOERROR twitter.com. 31919 IN A 59.24.3.173
twitter.com pointer-0 china-blackhole-4 NOERROR twitter.com. 11862 IN A 59.24.3.173
example.com pointer-1 google-dns1 NOERROR example.com. 4224 IN A 93.184.216.119
example.com pointer-1 google-dns2 NOERROR example.com. 4223 IN A 93.184.216.119
example.com pointer-1 opendns1 NOERROR example.com. 27947 IN A 93.184.216.119
example.com pointer-1 opendns2 NOERROR example.com. 31038 IN A 93.184.216.119
example.com pointer-1 twitter-ns1 
example.com pointer-1 twitter-ns2 
example.com pointer-1 he-dns FORMERR 
example.com pointer-1 level3 NOERROR example.com. 69002 IN A 93.184.216.119
example.com pointer-1 alidns1 
example.com pointer-1 alidns2 
example.com pointer-1 cnnic-dns1 
example.com pointer-1 v2ex-dns1 NOERROR example.com. 14598 IN A 93.184.216.119
example.com pointer-1 unicom-sh1 REFUSED 
example.com pointer-1 unicom-sh2 
example.com pointer-1 china-blackhole-1 
example.com pointer-1 china-blackhole-2 
example.com pointer-1 china-blackhole-3 
example.com pointer-1 china-blackhole-4 
twitter.com pointer-1 google-dns1 NOERROR twitter.com. 3 IN A 199.16.156.198 twitter.com. 3 IN A 199.16.156.6 twitter.com. 3 IN A 199.16.156.102 twitter.com. 3 IN A 199.16.156.230
twitter.com pointer-1 google-dns2 NOERROR twitter.com. 3 IN A 199.16.156.70 twitter.com. 3 IN A 199.16.156.102 twitter.com. 3 IN A 199.16.156.198 twitter.com. 3 IN A 199.16.156.38
twitter.com pointer-1 opendns1 NOERROR twitter.com. 25 IN A 199.16.156.198 twitter.com. 25 IN A 199.16.156.102 twitter.com. 25 IN A 199.16.156.70 twitter.com. 25 IN A 199.16.156.230
twitter.com pointer-1 opendns2 NOERROR twitter.com. 25 IN A 199.16.156.198 twitter.com. 25 IN A 199.16.156.102 twitter.com. 25 IN A 199.16.156.70 twitter.com. 25 IN A 199.16.156.230
twitter.com pointer-1 twitter-ns1 
twitter.com pointer-1 twitter-ns2 
twitter.com pointer-1 he-dns FORMERR 
twitter.com pointer-1 level3 NOERROR twitter.com. 18 IN A 199.16.156.38 twitter.com. 18 IN A 199.16.156.70 twitter.com. 18 IN A 199.16.156.6 twitter.com. 18 IN A 199.16.156.198
twitter.com pointer-1 alidns1 
twitter.com pointer-1 alidns2 
twitter.com pointer-1 cnnic-dns1 
twitter.com pointer-1 v2ex-dns1 NOERROR twitter.com. 21 IN A 199.59.148.82 twitter.com. 21 IN A 199.59.149.198 twitter.com. 21 IN A 199.59.150.7 twitter.com. 21 IN A 199.59.148.10
twitter.com pointer-1 unicom-sh1 REFUSED 
twitter.com pointer-1 unicom-sh2 
twitter.com pointer-1 china-blackhole-1 
twitter.com pointer-1 china-blackhole-2 
twitter.com pointer-1 china-blackhole-3 
twitter.com pointer-1 china-blackhole-4 
example.com pointer-4 google-dns1 NOERROR example.com. 4182 IN A 93.184.216.119
example.com pointer-4 google-dns2 NOERROR example.com. 4182 IN A 93.184.216.119
example.com pointer-4 opendns1 NOERROR example.com. 28298 IN A 93.184.216.119
example.com pointer-4 opendns2 NOERROR example.com. 30996 IN A 93.184.216.119
example.com pointer-4 twitter-ns1 
example.com pointer-4 twitter-ns2 
example.com pointer-4 he-dns FORMERR 
example.com pointer-4 level3 NOERROR example.com. 68961 IN A 93.184.216.119
example.com pointer-4 alidns1 
example.com pointer-4 alidns2 
example.com pointer-4 cnnic-dns1 
example.com pointer-4 v2ex-dns1 NOERROR example.com. 14557 IN A 93.184.216.119
example.com pointer-4 unicom-sh1 REFUSED 
example.com pointer-4 unicom-sh2 
example.com pointer-4 china-blackhole-1 
example.com pointer-4 china-blackhole-2 
example.com pointer-4 china-blackhole-3 
example.com pointer-4 china-blackhole-4 
twitter.com pointer-4 google-dns1 NOERROR twitter.com. 19 IN A 199.16.156.38 twitter.com. 19 IN A 199.16.156.198 twitter.com. 19 IN A 199.16.156.6 twitter.com. 19 IN A 199.16.156.102
twitter.com pointer-4 google-dns2 NOERROR twitter.com. 19 IN A 199.16.156.198 twitter.com. 19 IN A 199.16.156.38 twitter.com. 19 IN A 199.16.156.230 twitter.com. 19 IN A 199.16.156.70
twitter.com pointer-4 opendns1 NOERROR twitter.com. 4 IN A 199.16.156.70 twitter.com. 4 IN A 199.16.156.6 twitter.com. 4 IN A 199.16.156.198 twitter.com. 4 IN A 199.16.156.38
twitter.com pointer-4 opendns2 NOERROR twitter.com. 30 IN A 199.16.156.102 twitter.com. 30 IN A 199.16.156.230 twitter.com. 30 IN A 199.16.156.6 twitter.com. 30 IN A 199.16.156.38
twitter.com pointer-4 twitter-ns1 
twitter.com pointer-4 twitter-ns2 
twitter.com pointer-4 he-dns FORMERR 
twitter.com pointer-4 level3 FORMERR 
twitter.com pointer-4 alidns1 
twitter.com pointer-4 alidns2 
twitter.com pointer-4 cnnic-dns1 
twitter.com pointer-4 v2ex-dns1 NOERROR twitter.com. 9 IN A 199.59.150.7 twitter.com. 9 IN A 199.59.148.82 twitter.com. 9 IN A 199.59.149.230 twitter.com. 9 IN A 199.59.148.10
twitter.com pointer-4 unicom-sh1 REFUSED 
twitter.com pointer-4 unicom-sh2 
twitter.com pointer-4 china-blackhole-1 
twitter.com pointer-4 china-blackhole-2 
twitter.com pointer-4 china-blackhole-3 
twitter.com pointer-4 china-blackhole-4 
example.com pointer-append google-dns1 NOERROR example.com. 4141 IN A 93.184.216.119
example.com pointer-append google-dns2 NOERROR example.com. 4141 IN A 93.184.216.119
example.com pointer-append opendns1 FORMERR 
example.com pointer-append opendns2 FORMERR 
example.com pointer-append twitter-ns1 
example.com pointer-append twitter-ns2 
example.com pointer-append he-dns parse error
example.com pointer-append level3 
example.com pointer-append alidns1 
example.com pointer-append alidns2 
example.com pointer-append cnnic-dns1 
example.com pointer-append v2ex-dns1 NOERROR example.com. 14513 IN A 93.184.216.119
example.com pointer-append unicom-sh1 FORMERR 
example.com pointer-append unicom-sh2 FORMERR 
example.com pointer-append china-blackhole-1 
example.com pointer-append china-blackhole-2 
example.com pointer-append china-blackhole-3 
example.com pointer-append china-blackhole-4 
twitter.com pointer-append google-dns1 NOERROR twitter.com. 6 IN A 199.16.156.70 twitter.com. 6 IN A 199.16.156.230 twitter.com. 6 IN A 199.16.156.6 twitter.com. 6 IN A 199.16.156.198
twitter.com pointer-append google-dns2 NOERROR twitter.com. 6 IN A 199.16.156.70 twitter.com. 6 IN A 199.16.156.38 twitter.com. 6 IN A 199.16.156.102 twitter.com. 6 IN A 199.16.156.6
twitter.com pointer-append opendns1 FORMERR 
twitter.com pointer-append opendns2 FORMERR 
twitter.com pointer-append twitter-ns1 
twitter.com pointer-append twitter-ns2 
twitter.com pointer-append he-dns parse error
twitter.com pointer-append level3 parse error
twitter.com pointer-append alidns1 
twitter.com pointer-append alidns2 
twitter.com pointer-append cnnic-dns1 
twitter.com pointer-append v2ex-dns1 NOERROR twitter.com. 25 IN A 199.59.148.82 twitter.com. 25 IN A 199.59.149.198 twitter.com. 25 IN A 199.59.148.10 twitter.com. 25 IN A 199.59.150.39
twitter.com pointer-append unicom-sh1 FORMERR 
twitter.com pointer-append unicom-sh2 FORMERR 
twitter.com pointer-append china-blackhole-1 
twitter.com pointer-append china-blackhole-2 
twitter.com pointer-append china-blackhole-3 
twitter.com pointer-append china-blackhole-4 
example.com pointer-append-rr google-dns1 NOERROR example.com. 4100 IN A 93.184.216.119
example.com pointer-append-rr google-dns2 NOERROR example.com. 4100 IN A 93.184.216.119
example.com pointer-append-rr opendns1 FORMERR 
example.com pointer-append-rr opendns2 FORMERR 
example.com pointer-append-rr twitter-ns1 
example.com pointer-append-rr twitter-ns2 
example.com pointer-append-rr he-dns parse error
example.com pointer-append-rr level3 parse error
example.com pointer-append-rr alidns1 
example.com pointer-append-rr alidns2 
example.com pointer-append-rr cnnic-dns1 
example.com pointer-append-rr v2ex-dns1 NOERROR example.com. 14474 IN A 93.184.216.119
example.com pointer-append-rr unicom-sh1 FORMERR 
example.com pointer-append-rr unicom-sh2 FORMERR 
example.com pointer-append-rr china-blackhole-1 
example.com pointer-append-rr china-blackhole-2 
example.com pointer-append-rr china-blackhole-3 
example.com pointer-append-rr china-blackhole-4 
twitter.com pointer-append-rr google-dns1 NOERROR twitter.com. 26 IN A 199.16.156.102 twitter.com. 26 IN A 199.16.156.230 twitter.com. 26 IN A 199.16.156.38 twitter.com. 26 IN A 199.16.156.198
twitter.com pointer-append-rr google-dns2 NOERROR twitter.com. 26 IN A 199.16.156.198 twitter.com. 26 IN A 199.16.156.230 twitter.com. 26 IN A 199.16.156.38 twitter.com. 26 IN A 199.16.156.70
twitter.com pointer-append-rr opendns1 FORMERR 
twitter.com pointer-append-rr opendns2 FORMERR 
twitter.com pointer-append-rr twitter-ns1 
twitter.com pointer-append-rr twitter-ns2 
twitter.com pointer-append-rr he-dns parse error
twitter.com pointer-append-rr level3 NOERROR twitter.com. 4 IN A 199.16.156.230 twitter.com. 4 IN A 199.16.156.6 twitter.com. 4 IN A 199.16.156.198 twitter.com. 4 IN A 199.16.156.38
twitter.com pointer-append-rr alidns1 
twitter.com pointer-append-rr alidns2 
twitter.com pointer-append-rr cnnic-dns1 
twitter.com pointer-append-rr v2ex-dns1 NOERROR twitter.com. 16 IN A 199.59.148.10 twitter.com. 16 IN A 199.59.148.82 twitter.com. 16 IN A 199.59.149.198 twitter.com. 16 IN A 199.59.150.7
twitter.com pointer-append-rr unicom-sh1 FORMERR 
twitter.com pointer-append-rr unicom-sh2 FORMERR 
twitter.com pointer-append-rr china-blackhole-1 
twitter.com pointer-append-rr china-blackhole-2 
twitter.com pointer-append-rr china-blackhole-3 
twitter.com pointer-append-rr china-blackhole-4