src: add "typeof" build/parse/print support

This patch adds two new expression operations to build and to parse the
userdata area that describe the set key and data typeof definitions.

For maps, the grammar enforces either

"type data_type : data_type" or or "typeof expression : expression".

Check both key and data for valid user typeof info first.
If they check out, flag set->key_typeof_valid as true and use it for
printing the key info.

This patch comes with initial support for using payload expressions
with the 'typeof' keyword, followup patches will add support for other
expressions as well.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

2 files changed, 5 insertions, 0 deletions

diff --git a/include/expression.h b/include/expression.h
index d502fc2a..b3e79c49 100644
--- a/include/expression.h
+++ b/include/expression.h
@@ -10,6 +10,7 @@
 #include <utils.h>
 #include <list.h>
 #include <json.h>
+#include <libnftnl/udata.h>
 
 /**
  * enum expr_types
@@ -166,6 +167,9 @@ struct expr_ops {
 				       const struct expr *e2);
 	void			(*pctx_update)(struct proto_ctx *ctx,
 					       const struct expr *expr);
+	int			(*build_udata)(struct nftnl_udata_buf *udbuf,
+					       const struct expr *expr);
+	struct expr *		(*parse_udata)(const struct nftnl_udata *ud);
 };
 
 const struct expr_ops *expr_ops(const struct expr *e);
diff --git a/include/rule.h b/include/rule.h
index ce1f40db..6301fe35 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -307,6 +307,7 @@ struct set {
 	uint32_t		policy;
 	bool			root;
 	bool			automerge;
+	bool			key_typeof_valid;
 	struct {
 		uint32_t	size;
 	} desc;