Mirrors/coredns
1
0
Fork 0
mirror of https://github.com/coredns/coredns.git synced 2026-03-03 03:13:10 -05:00
Code Issues Packages Projects Releases Wiki Activity

fix(rewrite): fix cname target rewrite for CNAME chains (#7853)

Browse Source 
* fix(rewrite): fix cname target rewrite for CNAME chains

This fix corrects the cname target rewrite to handle CNAME chains:
- Preserves only the CNAME records before matching the rule
- Rewrites only the CNAME target that matches the rule
- Includes all records from the re-resolved upstream response

Signed-off-by: hide <hide@hide.net.eu.org>

* docs(rewrite): document how answer records are handled in CNAME target rewrite

Signed-off-by: hide <hide@hide.net.eu.org>

* fix(rewrite): simplify slice append per staticcheck S1011

Signed-off-by: hide <hide@hide.net.eu.org>

* docs(rewrite): add extra line between code and paragraph

Signed-off-by: hide <hide@hide.net.eu.org>

---------

Signed-off-by: hide <hide@hide.net.eu.org>
Co-authored-by: hide <hide@hide.net.eu.org>
This commit is contained in:
hide
2026-02-22 06:10:35 +09:00
committed by GitHub
parent 191a783e46
commit 78524a7921
3 changed files with 38 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
plugin/rewrite/README.md
View File

@@ -503,9 +503,9 @@ If only some calls contain the `revert` flag, then the value in the response wil
## CNAME Field Rewrites
There might be a scenario where you want the `CNAME` target of the response to be rewritten. You can do this by using the `CNAME` field rewrite. This will generate new answer records according to the new `CNAME` target.
There might be a scenario where you want the `CNAME` target of the response to be rewritten. You can do this by using the `CNAME` field rewrite. Answer records preceding the `CNAME` target are kept unchanged, the `CNAME` target is rewritten, and the subsequent records are replaced with the lookup result of the rewritten `CNAME` target.
The syntax for the CNAME rewrite rule is as follows. The meaning of
The syntax for the `CNAME` rewrite rule is as follows. The meaning of
`exact|prefix|suffix|substring|regex` is the same as with the name rewrite rules.
An omitted type is defaulted to `exact`.
@@ -527,7 +527,8 @@ $ dig @10.1.1.1 my-app.com
;my-app.com. IN A
;; ANSWER SECTION:
my-app.com. 200 IN CNAME my-app.com.cdn.example.net.
my-app.com. 200 IN CNAME my-app.example.
my-app.example. 200 IN CNAME my-app.com.cdn.example.net.
my-app.com.cdn.example.net. 300 IN A 20.2.0.1
my-app.com.cdn.example.net. 300 IN A 20.2.0.2
```
@@ -541,7 +542,9 @@ $ dig @10.1.1.1 my-app.com
;my-app.com. IN A
;; ANSWER SECTION:
my-app.com. 200 IN CNAME my-app.com.other.cdn.com.
my-app.com. 200 IN CNAME my-app.example.
my-app.example. 200 IN CNAME my-app.com.other.cdn.com.
my-app.com.other.cdn.com. 100 IN A 30.3.1.2
```
Note that the answer will contain a completely different set of answer records after rewriting the `CNAME` target.