how to rewrite ptr records

[sxauyhz]

for example, corefile :

rewriteng ANY ANY substring k8s.test.com  nginx-deploy.default.svc.cluster.local {
          answer name regex (.*)\.nginx-deploy.default.svc.cluster.local. {1}.k8s.test.com.
          answer data regex (.*)\.nginx-deploy.default.svc.cluster.local. {1}.k8s.test.com.
          authority both suffix nginx-deploy.default.svc.cluster.local. k8s.test.com.
          additional both suffix nginx-deploy.default.svc.cluster.local. k8s.test.com.
}

~]# nslookup nginx-rc1-77bpb.k8s 127.0.0.1
Server: 127.0.0.1
Address: 127.0.0.1#53

Name: nginx-rc1-77bpb.k8s.test.com
Address: 10.30.253.110

~]# nslookup 10.30.253.110 127.0.0.1
Server: 127.0.0.1
Address: 127.0.0.1#53

110.253.30.10.in-addr.arpa name = nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local.

### how to rewrite "nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local." to "nginx-rc1-77bpb.k8s.test.com" ??

[akissa]

The data rule should rewrite it, what do the logs state ?

[sxauyhz]

;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

Here is "nslookup nginx-rc1-77bpb.k8s.test.com" 127.0.0.1 logs :

;; QUESTION SECTION:
;nginx-rc1-77bpb.k8s.test.com.  IN       A

;; ANSWER SECTION:
nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local. 5       IN      A       10.30.253.110
2019-10-16T10:24:04.355+08:00 [INFO] plugin/rewriteng: calling rewriteAnswers -> rewriteDataParts for rr nginx-rc1-77bpb.k8s.test.com.  5       IN      A       10.30.253.110 rule &{substring 0xc0003f6b70 255 255 [0xc0003f6c00 0xc0003f6c90] [] []} answerRule answer

and here is "nslookup 10.30.253.110 127.0.0.1" logs:

2019-10-16T10:24:18.501+08:00 [INFO] plugin/rewriteng: plug-in calls RewriteNG
2019-10-16T10:24:18.501+08:00 [INFO] plugin/rewriteng: plug-in calls RewriteNG

@akissa
How to modify the configuration make 'nslookup 10.30.253.110 127.0.0.1' respone 'nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local. ' rewrite to 'nslookup nginx-rc1-77bpb.k8s.test.com'

[akissa]

You should be looking up PTR 110.253.30.10.in-addr.arpa.

[akissa]

dig @127.0.0.1 PTR 110.253.30.10.in-addr.arpa.

[sxauyhz]

dig @127.0.0.1 PTR 110.253.30.10.in-addr.arpa. Can not rewrie to 'nginx-rc1-77bpb.k8s.test.com', still is "nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local."
my cfg is:

rewriteng ANY ANY substring k8s.test.com  nginx-deploy.default.svc.cluster.local {
          answer name regex (.*)\.nginx-deploy.default.svc.cluster.local.$ {1}.k8s.test.com.
          answer data regex (.*)\.nginx-deploy.default.svc.cluster.local. {1}.k8s.test.com.
}

]# dig @127.0.0.1 PTR 110.253.30.10.in-addr.arpa.

; <<>> DiG 9.9.4-RedHat-9.9.4-38.el7_3.3 <<>> @127.0.0.1 PTR 110.253.30.10.in-addr.arpa.
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 640
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;110.253.30.10.in-addr.arpa. IN PTR

;; ANSWER SECTION:
110.253.30.10.in-addr.arpa. 5 IN PTR nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local.

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed Oct 16 14:18:39 CST 2019
;; MSG SIZE rcvd: 149

[akissa]

On a side note your regex is incorrect, you need to escape all the dots. What does the log show ?

[sxauyhz]

@akissa @kapilth
when escape all the dots, as follows:

rewriteng ANY ANY substring k8s.test.com  nginx-deploy.default.svc.cluster.local {
          answer name regex (.*)\.nginx-deploy\.default\.svc\.cluster\.local\.$ {1}.k8s.test.com.
          answer data regex (.*)\.nginx-deploy\.default\.svc\.cluster\.local\.$ {1}.k8s.test.com.
}

then test nslooup:

]# nslookup  nginx-rc1-77bpb.k8s.test.com 127.0.0.1
Server:		127.0.0.1
Address:	127.0.0.1#53

Name:	nginx-rc1-77bpb.k8s.test.com
Address: 10.30.253.110

]# nslookup 10.30.253.110 127.0.0.1
Server:		127.0.0.1
Address:	127.0.0.1#53

110.253.30.10.in-addr.arpa	name = nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local.

Looks like no change!!!
The logs as follows:

 ]# /usr/bin/coredns-v1.5.0 -conf /etc/coredns/Corefile
.:53
2019-10-16T14:59:02.763+08:00 [INFO] CoreDNS-1.5.0
2019-10-16T14:59:02.763+08:00 [INFO] linux/amd64, go1.13.1, e3f9a80-dirty
CoreDNS-1.5.0
linux/amd64, go1.13.1, e3f9a80-dirty

2019-10-16T14:59:05.636+08:00 [INFO] plugin/rewriteng: plug-in calls RewriteNG
2019-10-16T14:59:05.636+08:00 [INFO] plugin/rewriteng: plug-in calls RewriteNG
2019-10-16T14:59:05.636+08:00 [INFO] plugin/rewriteng: Calling next plugin: rewriteng
2019-10-16T14:59:05.636+08:00 [INFO] plugin/rewriteng: In ResponseWriter ;; opcode: QUERY, status: NOERROR, id: 40291
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;nginx-rc1-77bpb.k8s.test.com.  IN       A

;; ANSWER SECTION:
nginx-rc1-77bpb.nginx-deploy.default.svc.cluster.local. 5       IN      A       10.30.253.110
2019-10-16T14:59:05.636+08:00 [INFO] plugin/rewriteng: calling rewriteAnswers -> rewriteDataParts for rr nginx-rc1-77bpb.k8s.test.com.  5       IN      A       10.30.253.110 rule &{substring 0xc000414360 255 255 [0xc0004143f0 0xc000414480] [] []} answerRule answer
2019-10-16T14:59:12.925+08:00 [INFO] plugin/rewriteng: plug-in calls RewriteNG
2019-10-16T14:59:12.925+08:00 [INFO] plugin/rewriteng: plug-in calls RewriteNG