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plugin/rewrite: regular expression and substring match/replace (#1296) (#1297)

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Paul Greenberg
2017-12-13 11:31:19 -05:00
committed by John Belamaric
parent 556a289d9a
commit d35f2c73ec
4 changed files with 210 additions and 11 deletions
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45
plugin/rewrite/README.md
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@@ -96,3 +96,48 @@ rewrite edns0 subnet set 24 56
* If the query has source IP as IPv4, the first 24 bits in the IP will be the network subnet.
* If the query has source IP as IPv6, the first 56 bits in the IP will be the network subnet.
### Name Field Rewrites
The `rewrite` plugin offers the ability to match on the name in the question section of
a DNS request. The match could be exact, substring, or based on a prefix, suffix, or regular
expression.
The syntax for the name re-writing is as follows:
```
rewrite [continue|stop] name [exact|prefix|suffix|substring|regex] STRING STRING
```
The match type, i.e. `exact`, `substring`, etc., triggers re-write:
* **exact** (default): on exact match of the name in the question section of a request
* **substring**: on a partial match of the name in the question section of a request
* **prefix**: when the name begins with the matching string
* **suffix**: when the name ends with the matching string
* **regex**: when the name in the question section of a request matches a regular expression
If the match type is omitted, the `exact` match type is being assumed.
The following instruction allows re-writing the name in the query that
contains `service.us-west-1.example.org` substring.
```
rewrite name substring service.us-west-1.example.org service.us-west-1.consul
```
Thus:
* Incoming Request Name: `ftp.service.us-west-1.example.org`
* Re-written Request Name: `ftp.service.us-west-1.consul`
The following instruction uses regular expressions. The name in a request
matching `(.*)-(us-west-1)\.example\.org` regular expression is being replaces with
`{1}.service.{2}.consul`, where `{1}` and `{2}` are regular expression match groups.
```
rewrite name regex (.*)-(us-west-1)\.example\.org {1}.service.{2}.consul
```
Thus:
* Incoming Request Name: `ftp-us-west-1.example.org`
* Re-written Request Name: `ftp.service.us-west-1.consul`