Re: [RFC] concat with dynamically sized fields like vlan id

[Pablo Neira Ayuso <pablo@netfilter.org>]

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On Fri, May 01, 2020 at 10:59:15PM +0200, Michael Braun wrote:
> This enables commands like
> 
>  nft set bridge t s4 '{typeof vlan id . ip daddr; elements = { 3567 .
> 1.2.3.4 }; }'
> 
> Which would previously fail with
>   Error: can not use variable sized data types (integer) in concat
>   expressions

Now that typeof is in place, the integer_type can be set to 32-bits
(word size).

I would prefer to not expose the integer type definition to sets:

> +	set s4 {
> +		type integer . ipv4_addr
> +		elements = { 0 . 13.239.0.0 }
> +	}
> +

Users do not need to know that an 8-bit payload field is actually
aligned to 32-bits. Or that osf name is actually and 32-bit id number.

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diff --git a/src/datatype.c b/src/datatype.c
index 723ac649ea42..6a9b0239d37c 100644
--- a/src/datatype.c
+++ b/src/datatype.c
@@ -397,6 +397,7 @@ const struct datatype integer_type = {
 	.type		= TYPE_INTEGER,
 	.name		= "integer",
 	.desc		= "integer",
+	.size		= 4 * BITS_PER_BYTE,
 	.print		= integer_type_print,
 	.json		= integer_type_json,
 	.parse		= integer_type_parse,