[libnftnl PATCH 1/2] src/rule: Removed mandatory attribute printing in rules

[Alvaro Neira Ayuso <alvaroneay@gmail.com>]

From: Álvaro Neira Ayuso <alvaroneay@gmail.com>

Before this patch, the program tried to print some attribute
that maybe the user hasn't defined for printing. We can't
assume that the user want to print some attribute that we have put
mandatory in the rules. Example:

Before this patch, it's mandatory have a rule with family
and this is the output:

{"rule":{"family":"ip","handle":4...
<rule><family>ip</family><handle>4</handle>...

Now, we can print rule without some attribute:

{"rule":{"handle":4...
<rule><handle>4</handle>...

Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
---
 src/rule.c |   92 ++++++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 79 insertions(+), 13 deletions(-)

diff --git a/src/rule.c b/src/rule.c
index 162a0a1..f0cafd3 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -775,12 +775,32 @@ static int nft_rule_snprintf_json(char *buf, size_t size, struct nft_rule *r,
 	int ret, len = size, offset = 0;
 	struct nft_rule_expr *expr;
 
-	ret = snprintf(buf, len, "{\"rule\":{\"family\":\"%s\",\"table\":\"%s\","
-				 "\"chain\":\"%s\",\"handle\":%llu,",
-		       nft_family2str(r->family), r->table, r->chain,
-		       (unsigned long long)r->handle);
+	ret = snprintf(buf, len, "{\"rule\":{");
 	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
 
+	if (r->flags & (1 << NFT_RULE_ATTR_FAMILY)) {
+		ret = snprintf(buf+offset, len, "\"family\":\"%s\",",
+			       nft_family2str(r->family));
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	if (r->flags & (1 << NFT_RULE_ATTR_TABLE)) {
+		ret = snprintf(buf+offset, len, "\"table\":\"%s\",",
+			       r->table);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	if (r->flags & (1 << NFT_RULE_ATTR_CHAIN)) {
+		ret = snprintf(buf+offset, len, "\"chain\":\"%s\",",
+			       r->chain);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+	if (r->flags & (1 << NFT_RULE_ATTR_HANDLE)) {
+		ret = snprintf(buf+offset, len, "\"handle\":%llu,",
+			       (unsigned long long)r->handle);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
 	if (r->flags & (1 << NFT_RULE_ATTR_COMPAT_PROTO) ||
 	    r->flags & (1 << NFT_RULE_ATTR_COMPAT_FLAGS)) {
 		ret = snprintf(buf+offset, len, "\"compat_flags\":%u,"
@@ -824,13 +844,32 @@ static int nft_rule_snprintf_xml(char *buf, size_t size, struct nft_rule *r,
 	int ret, len = size, offset = 0;
 	struct nft_rule_expr *expr;
 
-	ret = snprintf(buf, len, "<rule><family>%s</family>"
-		       "<table>%s</table><chain>%s</chain>"
-		       "<handle>%llu</handle>",
-		       nft_family2str(r->family), r->table, r->chain,
-		       (unsigned long long)r->handle);
+	ret = snprintf(buf, len, "<rule>");
 	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
 
+	if (r->flags & (1 << NFT_RULE_ATTR_FAMILY)) {
+		ret = snprintf(buf+offset, len, "<family>%s</family>",
+			       nft_family2str(r->family));
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	if (r->flags & (1 << NFT_RULE_ATTR_TABLE)) {
+		ret = snprintf(buf+offset, len, "<table>%s</table>",
+			       r->table);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	if (r->flags & (1 << NFT_RULE_ATTR_CHAIN)) {
+		ret = snprintf(buf+offset, len, "<chain>%s</chain>",
+			       r->chain);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+	if (r->flags & (1 << NFT_RULE_ATTR_HANDLE)) {
+		ret = snprintf(buf+offset, len, "<handle>%llu</handle>",
+			       (unsigned long long)r->handle);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
 	if (r->compat.flags != 0 || r->compat.proto != 0) {
 		ret = snprintf(buf+offset, len,
 			       "<compat_flags>%u</compat_flags>"
@@ -865,15 +904,42 @@ static int nft_rule_snprintf_xml(char *buf, size_t size, struct nft_rule *r,
 	return offset;
 }
 
-static int nft_rule_snprintf_default(char *buf, size_t size, struct nft_rule *r, 
+static int nft_rule_snprintf_default(char *buf, size_t size, struct nft_rule *r,
 				     uint32_t type, uint32_t flags)
 {
 	struct nft_rule_expr *expr;
 	int ret, len = size, offset = 0, i;
 
-	ret = snprintf(buf, len, "%s %s %s %"PRIu64" %"PRIu64"\n",
-			nft_family2str(r->family), r->table, r->chain,
-			r->handle, r->position);
+	if (r->flags & (1 << NFT_RULE_ATTR_FAMILY)) {
+		ret = snprintf(buf+offset, len, "%s ",
+			       nft_family2str(r->family));
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	if (r->flags & (1 << NFT_RULE_ATTR_TABLE)) {
+		ret = snprintf(buf+offset, len, "%s ",
+			       r->table);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	if (r->flags & (1 << NFT_RULE_ATTR_CHAIN)) {
+		ret = snprintf(buf+offset, len, "%s ",
+			       r->chain);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+	if (r->flags & (1 << NFT_RULE_ATTR_TABLE)) {
+		ret = snprintf(buf+offset, len, "%llu ",
+			       (unsigned long long)r->handle);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	if (r->flags & (1 << NFT_RULE_ATTR_POSITION)) {
+		ret = snprintf(buf+offset, len, "%llu ",
+			       (unsigned long long)r->position);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+
+	ret = snprintf(buf+offset, len, "\n");
 	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
 
 	list_for_each_entry(expr, &r->expr_list, head) {

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