The test works as follows:
1. Client wants to resolve unusual ip6.arpa. name:
test1.test2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. IN TXT
2. Query is sent to ns7, a qmin enabled resolver.
3. ns7 do the first stage in query minimization for the name and send a new
query to root (ns1):
_.1.0.0.2.ip6.arpa. IN A
4. ns1 delegates ip6.arpa. to ns2.good.:
;; AUTHORITY SECTION:
;ip6.arpa. 20 IN NS ns2.good.
;; ADDITIONAL SECTION:
;ns2.good. 20 IN A 10.53.0.2
5. ns7 do a second round in minimizing the name and send a new query
to ns2.good. (10.53.0.2):
_.8.2.6.0.1.0.0.2.ip6.arpa. IN A
6. ans2 delegates 8.2.6.0.1.0.0.2.ip6.arpa. to ns3.good.:
;; AUTHORITY SECTION:
;8.2.6.0.1.0.0.2.ip6.arpa. 60 IN NS ns3.good.
;; ADDITIONAL SECTION:
;ns3.good. 60 IN A 10.53.0.3
7. ns7 do a third round in minimizing the name and send a new query to
ns3.good.:
_.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. IN A
8. ans3 delegates 1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. to ns4.good.:
;; AUTHORITY SECTION:
;1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. 60 IN NS ns4.good.
;; ADDITIONAL SECTION:
;ns4.good. 60 IN A 10.53.0.4
9. ns7 do fourth round in minimizing the name and send a new query to
ns4.good.:
_.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. IN A
10. ns4.good. doesn't know such name, but answers stating it is authoritative for
the domai:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 53815
...
;; AUTHORITY SECTION:
1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. 60 IN SOA ns4.good. ...
11. ns7 do another minimization on name:
_.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa
sends to ns4.good. and gets the same SOA response stated in item #10
12. ns7 do another minimization on name:
_.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa
sends to ns4.good. and gets the same SOA response stated in item #10.
13. ns7 do the last query minimization name for the ip6.arpa. QNAME.
After all IPv6 labels are exausted the algorithm falls back to the
original QNAME:
test1.test2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa
ns7 sends a new query with the original QNAME to ans4.
14. Finally ans4 answers with the expected response:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 40969
;; flags: qr aa; QUESTION: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 8192
;; QUESTION SECTION:
;test1.test2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. IN TXT
;; ANSWER SECTION:
;test1.test2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa. 1 IN TXT "long_ip6_name"
(cherry picked from commit 11add69198)
qname minimization, even in relaxed mode, can fail on
some very broken domains. In relaxed mode, instead of
asking for "foo.bar NS" ask for "_.foo.bar A" to either
get a delegation or NXDOMAIN. It will require more queries
than regular mode for proper NXDOMAINs.
