[Dnsmasq-discuss] address option doesn't work correctly if the target domain is a cname

Sat Apr 16 17:13:27 UTC 2022

Hello.

I'm using dnsmasq version 2.86.

I've found that address option works incorrectly if the target domain is 
a cname.

Here is an example:

1) Add a domain to dnsmasq configuration:

address=/api.ott.kinopoisk.ru/::

2) Make a DNS query for this domain. Everything is fine now: dnsmasq 
replies with an IPv4 address received from the upstream DNS server and 
an IPv6 address from the configuration file

root at veronika:~# nslookup api.ott.kinopoisk.ru
Server:         127.0.0.1
Address:        127.0.0.1:53

Name:   api.ott.kinopoisk.ru
Address: ::

Non-authoritative answer:
api.ott.kinopoisk.ru    canonical name = 
ott-api-production-balancer.ott.yandex.net
Name:   ott-api-production-balancer.ott.yandex.net
Address: 93.158.134.102

Sat Apr 16 19:13:20 2022 daemon.info dnsmasq[1]: 419 127.0.0.1/58719 
query[A] api.ott.kinopoisk.ru from 127.0.0.1
Sat Apr 16 19:13:20 2022 daemon.info dnsmasq[1]: 419 127.0.0.1/58719 
forwarded api.ott.kinopoisk.ru to 213.234.192.7
Sat Apr 16 19:13:20 2022 daemon.info dnsmasq[1]: 420 127.0.0.1/58719 
query[AAAA] api.ott.kinopoisk.ru from 127.0.0.1
Sat Apr 16 19:13:20 2022 daemon.info dnsmasq[1]: 420 127.0.0.1/58719 
config api.ott.kinopoisk.ru is ::
Sat Apr 16 19:13:20 2022 daemon.info dnsmasq[1]: 419 127.0.0.1/58719 
reply api.ott.kinopoisk.ru is <CNAME>
Sat Apr 16 19:13:20 2022 daemon.info dnsmasq[1]: 419 127.0.0.1/58719 
reply ott-api-production-balancer.ott.yandex.net is 93.158.134.102

3) You may repeat a query and everything is still fine:

root at veronika:~# nslookup api.ott.kinopoisk.ru
Server:         127.0.0.1
Address:        127.0.0.1:53

Non-authoritative answer:
api.ott.kinopoisk.ru    canonical name = 
ott-api-production-balancer.ott.yandex.net
Name:   ott-api-production-balancer.ott.yandex.net
Address: 93.158.134.102

Name:   api.ott.kinopoisk.ru
Address: ::

Sat Apr 16 19:13:26 2022 daemon.info dnsmasq[1]: 431 127.0.0.1/34089 
query[A] api.ott.kinopoisk.ru from 127.0.0.1
Sat Apr 16 19:13:26 2022 daemon.info dnsmasq[1]: 431 127.0.0.1/34089 
cached api.ott.kinopoisk.ru is <CNAME>
Sat Apr 16 19:13:26 2022 daemon.info dnsmasq[1]: 431 127.0.0.1/34089 
cached ott-api-production-balancer.ott.yandex.net is 93.158.134.102
Sat Apr 16 19:13:26 2022 daemon.info dnsmasq[1]: 432 127.0.0.1/34089 
query[AAAA] api.ott.kinopoisk.ru from 127.0.0.1
Sat Apr 16 19:13:26 2022 daemon.info dnsmasq[1]: 432 127.0.0.1/34089 
cached api.ott.kinopoisk.ru is <CNAME>
Sat Apr 16 19:13:26 2022 daemon.info dnsmasq[1]: 432 127.0.0.1/34089 
config api.ott.kinopoisk.ru is ::

4) Now query the original domain to which our configured domain points to:

root at veronika:~# nslookup ott-api-production-balancer.ott.yandex.net
Server:         127.0.0.1
Address:        127.0.0.1:53

Non-authoritative answer:
Name:   ott-api-production-balancer.ott.yandex.net
Address: 93.158.134.102

Non-authoritative answer:
Name:   ott-api-production-balancer.ott.yandex.net
Address: 2a02:6b8::272

Sat Apr 16 19:13:33 2022 daemon.info dnsmasq[1]: 442 127.0.0.1/51782 
query[A] ott-api-production-balancer.ott.yandex.net from 127.0.0.1
Sat Apr 16 19:13:33 2022 daemon.info dnsmasq[1]: 442 127.0.0.1/51782 
cached ott-api-production-balancer.ott.yandex.net is 93.158.134.102
Sat Apr 16 19:13:33 2022 daemon.info dnsmasq[1]: 443 127.0.0.1/51782 
query[AAAA] ott-api-production-balancer.ott.yandex.net from 127.0.0.1
Sat Apr 16 19:13:33 2022 daemon.info dnsmasq[1]: 443 127.0.0.1/51782 
forwarded ott-api-production-balancer.ott.yandex.net to 213.234.192.7
Sat Apr 16 19:13:33 2022 daemon.info dnsmasq[1]: 443 127.0.0.1/51782 
reply ott-api-production-balancer.ott.yandex.net is 2a02:6b8::272

5) Let's query our configured domain again. Now you can see that dnsmasq 
starts to reply with IPv6 from upstream server instead of our configured 
IPv6:

root at veronika:~# nslookup api.ott.kinopoisk.ru
Server:         127.0.0.1
Address:        127.0.0.1:53

Non-authoritative answer:
api.ott.kinopoisk.ru    canonical name = 
ott-api-production-balancer.ott.yandex.net
Name:   ott-api-production-balancer.ott.yandex.net
Address: 93.158.134.102

Non-authoritative answer:
api.ott.kinopoisk.ru    canonical name = 
ott-api-production-balancer.ott.yandex.net
Name:   ott-api-production-balancer.ott.yandex.net
Address: 2a02:6b8::272

Sat Apr 16 19:13:37 2022 daemon.info dnsmasq[1]: 458 127.0.0.1/35410 
query[A] api.ott.kinopoisk.ru from 127.0.0.1
Sat Apr 16 19:13:37 2022 daemon.info dnsmasq[1]: 458 127.0.0.1/35410 
cached api.ott.kinopoisk.ru is <CNAME>
Sat Apr 16 19:13:37 2022 daemon.info dnsmasq[1]: 458 127.0.0.1/35410 
cached ott-api-production-balancer.ott.yandex.net is 93.158.134.102
Sat Apr 16 19:13:37 2022 daemon.info dnsmasq[1]: 459 127.0.0.1/35410 
query[AAAA] api.ott.kinopoisk.ru from 127.0.0.1
Sat Apr 16 19:13:37 2022 daemon.info dnsmasq[1]: 459 127.0.0.1/35410 
cached api.ott.kinopoisk.ru is <CNAME>
Sat Apr 16 19:13:37 2022 daemon.info dnsmasq[1]: 459 127.0.0.1/35410 
cached ott-api-production-balancer.ott.yandex.net is 2a02:6b8::272