[libnftnl PATCH 2/3] expr: nat: Do not print unset values in xml file

[Ana Rey <anarey@gmail.com>]

It changes the parse functions to omit unset values.

Now, It possible to use a xml file like this:
[...]
<expr type="nat">
        <type>snat</type>
        <family>ip</family>
        <sreg_addr_min>1</sreg_addr_min>
        <sreg_addr_max>1</sreg_addr_max>
</expr></rule>

Signed-off-by: Ana Rey <anarey@gmail.com>
---
 src/expr/nat.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/src/expr/nat.c b/src/expr/nat.c
index 46d5ed7..c10f0ff 100644
--- a/src/expr/nat.c
+++ b/src/expr/nat.c
@@ -283,24 +283,20 @@ static int nft_rule_expr_nat_xml_parse(struct nft_rule_expr *e, mxml_node_t *tre
 	nft_rule_expr_set_u32(e, NFT_EXPR_NAT_FAMILY, family);
 
 	if (nft_mxml_reg_parse(tree, "sreg_addr_min", &reg_addr_min,
-			       MXML_DESCEND, NFT_XML_MAND, err) < 0)
-		return -1;
-	nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_ADDR_MIN, reg_addr_min);
+			       MXML_DESCEND, NFT_XML_MAND, err) == 0)
+		nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_ADDR_MIN, reg_addr_min);
 
 	if (nft_mxml_reg_parse(tree, "sreg_addr_max", &reg_addr_max,
-			       MXML_DESCEND, NFT_XML_MAND, err) < 0)
-		return -1;
-	nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_ADDR_MAX, reg_addr_max);
+			       MXML_DESCEND, NFT_XML_MAND, err) == 0)
+		nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_ADDR_MAX, reg_addr_max);
 
 	if (nft_mxml_reg_parse(tree, "sreg_proto_min", &reg_proto_min,
-			       MXML_DESCEND, NFT_XML_MAND, err) < 0)
-		return -1;
-	nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_PROTO_MIN, reg_proto_min);
+			       MXML_DESCEND, NFT_XML_MAND, err) == 0)
+		nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_PROTO_MIN, reg_proto_min);
 
 	if (nft_mxml_reg_parse(tree, "sreg_proto_max", &reg_proto_max,
-			       MXML_DESCEND, NFT_XML_MAND, err) < 0)
-		return -1;
-	nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_PROTO_MAX, reg_proto_max);
+			       MXML_DESCEND, NFT_XML_MAND, err) == 0)
+		nft_rule_expr_set_u32(e, NFT_EXPR_NAT_REG_PROTO_MAX, reg_proto_max);
 
 	return 0;
 #else
-- 
2.0.0