rule: don't print unset attributes

We 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:

If we have defined family, the output is like that:

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

And this if we unset the family.

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

Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 79 insertions, 13 deletions

diff --git a/src/rule.c b/src/rule.c
index 162a0a1..3aaee71 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_HANDLE)) {
+		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) {