[PATCH] comment: Add translation to nft

[Shivani Bhardwaj <shivanib134@gmail.com>]

Add translation for match comment to nftables.

Example:

$ sudo iptables-translate -A INPUT -s 192.168.0.0 -m comment --comment "A privatized IP block"
nft add rule ip filter INPUT ip saddr 192.168.0.0 counter comment \"A privatized IP block\"

Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
---
 extensions/libxt_comment.c | 13 +++++++++++++
 iptables/nft-ipv4.c        | 17 +++++++++++++++--
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/extensions/libxt_comment.c b/extensions/libxt_comment.c
index 6ed2ff9..e80336c 100644
--- a/extensions/libxt_comment.c
+++ b/extensions/libxt_comment.c
@@ -48,6 +48,18 @@ comment_save(const void *ip, const struct xt_entry_match *match)
 	xtables_save_string(commentinfo->comment);
 }
 
+static int
+comment_xlate(const struct xt_entry_match *match,
+	      struct xt_buf *buf, int numeric)
+{
+	struct xt_comment_info *commentinfo = (void *)match->data;
+
+	commentinfo->comment[XT_MAX_COMMENT_LEN-1] = '\0';
+	xt_buf_add(buf, "comment \\\"%s\\\" ", commentinfo->comment);
+
+	return 1;
+}
+
 static struct xtables_match comment_match = {
 	.family		= NFPROTO_UNSPEC,
 	.name		= "comment",
@@ -59,6 +71,7 @@ static struct xtables_match comment_match = {
 	.save 		= comment_save,
 	.x6_parse	= xtables_option_parse,
 	.x6_options	= comment_opts,
+	.xlate		= comment_xlate,
 };
 
 void _init(void)
diff --git a/iptables/nft-ipv4.c b/iptables/nft-ipv4.c
index ede8f17..612b4f6 100644
--- a/iptables/nft-ipv4.c
+++ b/iptables/nft-ipv4.c
@@ -433,6 +433,7 @@ static int nft_ipv4_xlate(const void *data, struct xt_buf *buf)
 {
 	const struct iptables_command_state *cs = data;
 	int ret;
+	bool comm = false;
 
 	if (cs->fw.ip.iniface[0] != '\0') {
 		xt_buf_add(buf, "iifname %s%s ",
@@ -477,12 +478,24 @@ static int nft_ipv4_xlate(const void *data, struct xt_buf *buf)
 			   inet_ntoa(cs->fw.ip.dst));
 	}
 
+	/*
+	 * Add counter for match comment as prefix
+	 */
+	if (strcmp(cs->matches->match->name, "comment") == 0) {
+		comm = true;
+		xt_buf_add(buf, "counter ");
+	}
+
 	ret = xlate_matches(cs, buf);
 	if (!ret)
 		return ret;
 
-	/* Always add counters per rule, as in iptables */
-	xt_buf_add(buf, "counter ");
+	/*
+	 * Always add counters per rule, as in iptables
+	 * except for the match comment
+	 */
+	if (!comm)
+		xt_buf_add(buf, "counter ");
 
 	ret = xlate_action(cs, !!(cs->fw.ip.flags & IPT_F_GOTO), buf);
 
-- 
1.9.1