[libnftnl,3/5] expr: seperate expression parsing and building functions

diff --git a/include/expr.h b/include/expr.h
index ed41105..a4333c6 100644
--- a/include/expr.h
+++ b/include/expr.h
@@ -10,4 +10,10 @@  struct nft_rule_expr {
 	uint8_t			data[];
 };
 
+struct nlmsghdr;
+
+void nft_rule_expr_build_payload(struct nlmsghdr *nlh, struct nft_rule_expr *expr);
+struct nft_rule_expr *nft_rule_expr_parse(struct nlattr *attr);
+
+
 #endif
diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index 7bc0273..14daa83 100644
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -36,10 +36,6 @@  uint32_t nft_rule_expr_get_u32(const struct nft_rule_expr *expr, uint16_t type);
 uint64_t nft_rule_expr_get_u64(const struct nft_rule_expr *expr, uint16_t type);
 const char *nft_rule_expr_get_str(const struct nft_rule_expr *expr, uint16_t type);
 
-struct nlmsghdr;
-
-void nft_rule_expr_build_payload(struct nlmsghdr *nlh, struct nft_rule_expr *expr);
-
 int nft_rule_expr_snprintf(char *buf, size_t buflen, struct nft_rule_expr *expr, uint32_t type, uint32_t flags);
 
 enum {
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)
diff --git a/src/libnftnl.map b/src/libnftnl.map
index 01eba13..c2b9431 100644
--- a/src/libnftnl.map
+++ b/src/libnftnl.map
@@ -102,7 +102,6 @@  global:
   nft_rule_expr_get_u32;
   nft_rule_expr_get_u64;
   nft_rule_expr_get_str;
-  nft_rule_expr_build_payload;
   nft_rule_expr_snprintf;
   nft_rule_expr_free;
 
diff --git a/src/rule.c b/src/rule.c
index 3feb337..04088ed 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -277,7 +277,7 @@  EXPORT_SYMBOL(nft_rule_attr_get_u8);
 void nft_rule_nlmsg_build_payload(struct nlmsghdr *nlh, struct nft_rule *r)
 {
 	struct nft_rule_expr *expr;
-	struct nlattr *nest;
+	struct nlattr *nest, *nest2;
 
 	if (r->flags & (1 << NFT_RULE_ATTR_TABLE))
 		mnl_attr_put_strz(nlh, NFTA_RULE_TABLE, r->table);
@@ -295,7 +295,9 @@  void nft_rule_nlmsg_build_payload(struct nlmsghdr *nlh, struct nft_rule *r)
 	if (!list_empty(&r->expr_list)) {
 		nest = mnl_attr_nest_start(nlh, NFTA_RULE_EXPRESSIONS);
 		list_for_each_entry(expr, &r->expr_list, head) {
+			nest2 = mnl_attr_nest_start(nlh, NFTA_LIST_ELEM);
 			nft_rule_expr_build_payload(nlh, expr);
+			mnl_attr_nest_end(nlh, nest2);
 		}
 		mnl_attr_nest_end(nlh, nest);
 	}
@@ -355,61 +357,20 @@  static int nft_rule_parse_attr_cb(const struct nlattr *attr, void *data)
 	return MNL_CB_OK;
 }
 
-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;
-}
-
-static int nft_rule_parse_expr2(struct nlattr *attr, struct nft_rule *r)
-{
-	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)
-		return -1;
-
-	expr = nft_rule_expr_alloc(mnl_attr_get_str(tb[NFTA_EXPR_NAME]));
-	if (expr == NULL)
-		return -1;
-
-	if (tb[NFTA_EXPR_DATA]) {
-		if (expr->ops->parse(expr, tb[NFTA_EXPR_DATA]) < 0) {
-			xfree(expr);
-			return -1;
-		}
-	}
-	list_add_tail(&expr->head, &r->expr_list);
-
-	return 0;
-}
-
 static int nft_rule_parse_expr(struct nlattr *nest, struct nft_rule *r)
 {
+	struct nft_rule_expr *expr;
 	struct nlattr *attr;
 
 	mnl_attr_for_each_nested(attr, nest) {
 		if (mnl_attr_get_type(attr) != NFTA_LIST_ELEM)
 			return -1;
 
-		nft_rule_parse_expr2(attr, r);
+		expr = nft_rule_expr_parse(attr);
+		if (expr == NULL)
+			return -1;
+
+		list_add_tail(&expr->head, &r->expr_list);
 	}
 	return 0;
 }