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Try to clarify rewrite docs (#1795)

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making response rewrites more prominent
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Chris O'Haver 2018-05-11 13:50:59 -04:00 • committed by GitHub
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plugin/rewrite/README.md
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@ -11,24 +11,20 @@ Rewrites are invisible to the client. There are simple rewrites (fast) and compl
## Syntax
A simplified/easy to digest syntax for *rewrite* is...
~~~
rewrite [continue|stop] FIELD FROM TO
~~~
* **FIELD** is (`type`, `class`, `name`, ...)
* **FROM** is the exact name of type to match
* **TO** is the destination name or type to rewrite to
When the FIELD is `type` and FROM is (`A`, `MX`, etc.), the type of the message will be rewritten;
* **FIELD** indicates what part of the request/response is being re-written.
* `type` - the type field of the request will be rewritten. FROM/TO must be a DNS record type (`A`, `MX`, etc);
e.g., to rewrite ANY queries to HINFO, use `rewrite type ANY HINFO`.
When the FIELD is `class` and FROM is (`IN`, `CH`, or `HS`) the class of the message will be
rewritten; e.g., to rewrite CH queries to IN use `rewrite class CH IN`.
When the FIELD is `name` the query name in the message is rewritten; this
needs to be a full match of the name, e.g., `rewrite name miek.nl example.org`.
When the FIELD is `edns0` an EDNS0 option can be appended to the request as described below.
* `class` - the class of the message will be rewritten. FROM/TO must be a DNS class type (`IN`, `CH`, or `HS`) e.g., to rewrite CH queries to IN use `rewrite class CH IN`.
* `name` - the query name in the _request_ is rewritten; by default this is a full match of the name, e.g., `rewrite name miek.nl example.org`. Other match types are supported, see the **Name Field Rewrites** section below.
* `answer name` - the query name in the _response_ is rewritten. This option has special restrictions and requirements, in particular it must always combined with a `name` rewrite. See below in the **Response Rewrites** section.
* `edns0` - an EDNS0 option can be appended to the request as described below in the **EDNS0 Options** section.
* **FROM** is the name or type to match
* **TO** is the destination name or type to rewrite to
If you specify multiple rules and an incoming query matches on multiple rules, the rewrite
will behave as following
@ -235,3 +231,13 @@ 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.
## Full Syntax
The full plugin usage syntax is harder to digest...
~~~
rewrite [continue|stop] {type|class|edns0|name [exact|prefix|suffix|substring|regex [FROM TO answer name]]} FROM TO
~~~
The syntax above doesn't cover the multi line block option for specifying a name request+response rewrite rule described in the **Response Rewrite** section.