[PATCH nft 5/5] sets: inform user when set definition contains unknown attributes

[Florian Westphal <fw@strlen.de>]

libnftnl detects when the kernel includes extra attributes that are not
recognized.  Expose this to the user.

This could happen when using an older release of libnftl/nftables
with a more recent kernel, where a raw user of the netlink interface
uses an extended/more recent feature set.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/rule.h | 2 ++
 src/netlink.c  | 3 +++
 src/rule.c     | 5 +++++
 3 files changed, 10 insertions(+)

diff --git a/include/rule.h b/include/rule.h
index 5b3e12b5d7dc..7cbd26897321 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -332,6 +332,7 @@ void rule_stmt_insert_at(struct rule *rule, struct stmt *nstmt,
  * @automerge:	merge adjacents and overlapping elements, if possible
  * @comment:	comment
  * @errors:	expr evaluation errors seen
+ * @incomplete: kernel set additional attributes unknown to this nft version
  * @desc.size:		count of set elements
  * @desc.field_len:	length of single concatenated fields, bytes
  * @desc.field_count:	count of concatenated fields
@@ -357,6 +358,7 @@ struct set {
 	bool			automerge;
 	bool			key_typeof_valid;
 	bool			errors;
+	bool			incomplete;
 	const char		*comment;
 	struct {
 		uint32_t	size;
diff --git a/src/netlink.c b/src/netlink.c
index 25ee3419772b..c057e1d04c28 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -1032,6 +1032,9 @@ struct set *netlink_delinearize_set(struct netlink_ctx *ctx,
 	if (comment)
 		set->comment = xstrdup(comment);
 
+	if (!nftnl_set_complete(nls))
+		set->incomplete = true;
+
 	init_list_head(&set_parse_ctx.stmt_list);
 
 	if (nftnl_set_is_set(nls, NFTNL_SET_EXPR)) {
diff --git a/src/rule.c b/src/rule.c
index 9bc160ec0d88..e4fce143d8be 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -405,6 +405,11 @@ static void set_print_declaration(const struct set *set,
 			  set->comment,
 			  opts->stmt_separator);
 	}
+
+	if (set->incomplete)
+		nft_print(octx, "%s%s# Unknown features used (old nft version?)%s",
+			  opts->tab, opts->tab,
+			  opts->stmt_separator);
 }
 
 static void do_set_print(const struct set *set, struct print_fmt_options *opts,
-- 
2.45.2