expr: seperate expression parsing and building functions

The expression build function currently assumes to be only used from
rule context and actually builds rule attributes. Fix that and only
build the expression. Also it seems to have been exported by accident,
undo that.

Additionally, move the expression parsing function from rule parsing
and also remove any assumptions about being used in rule context.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 50 insertions, 6 deletions

diff --git a/src/expr.c b/src/expr.c
index 79782fa..4109495 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -15,6 +15,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
 #include <netinet/in.h>
 
 #include <libmnl/libmnl.h>
@@ -205,18 +206,61 @@ EXPORT_SYMBOL(nft_rule_expr_get_str);
 void
 nft_rule_expr_build_payload(struct nlmsghdr *nlh, struct nft_rule_expr *expr)
 {
-	struct nlattr *nest1, *nest2;
+	struct nlattr *nest;
 
-	nest1 = mnl_attr_nest_start(nlh, NFTA_LIST_ELEM);
 	mnl_attr_put_strz(nlh, NFTA_EXPR_NAME, expr->ops->name);
 
-	nest2 = mnl_attr_nest_start(nlh, NFTA_EXPR_DATA);
+	nest = mnl_attr_nest_start(nlh, NFTA_EXPR_DATA);
 	expr->ops->build(nlh, expr);
-	mnl_attr_nest_end(nlh, nest2);
+	mnl_attr_nest_end(nlh, nest);
+}
+
+static int nft_rule_parse_expr_cb(const struct nlattr *attr, void *data)
+{
+	const struct nlattr **tb = data;
+	int type = mnl_attr_get_type(attr);
+
+	if (mnl_attr_type_valid(attr, NFTA_EXPR_MAX) < 0)
+		return MNL_CB_OK;
+
+	switch (type) {
+	case NFTA_EXPR_NAME:
+		if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
+			abi_breakage();
+		break;
+	case NFTA_EXPR_DATA:
+		if (mnl_attr_validate(attr, MNL_TYPE_NESTED) < 0)
+			abi_breakage();
+		break;
+	}
+
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
 
-	mnl_attr_nest_end(nlh, nest1);
+struct nft_rule_expr *nft_rule_expr_parse(struct nlattr *attr)
+{
+	struct nlattr *tb[NFTA_EXPR_MAX+1] = {};
+	struct nft_rule_expr *expr;
+
+	if (mnl_attr_parse_nested(attr, nft_rule_parse_expr_cb, tb) < 0)
+		goto err1;
+
+	expr = nft_rule_expr_alloc(mnl_attr_get_str(tb[NFTA_EXPR_NAME]));
+	if (expr == NULL)
+		goto err1;
+
+	if (tb[NFTA_EXPR_DATA] &&
+	    expr->ops->parse(expr, tb[NFTA_EXPR_DATA]) < 0)
+		goto err2;
+
+	return expr;
+
+err2:
+	xfree(expr);
+err1:
+	return NULL;
 }
-EXPORT_SYMBOL(nft_rule_expr_build_payload);
 
 int nft_rule_expr_snprintf(char *buf, size_t size, struct nft_rule_expr *expr,
 			   uint32_t type, uint32_t flags)