[PATCH v2] extensions: libxt_helper: Add translation to nft

[Shivani Bhardwaj <shivanib134@gmail.com>]

Add translation for helper module to nftables.

Examples:

$ sudo iptables-translate -A FORWARD -m helper --helper sip
nft add rule ip filter FORWARD ct helper \"sip\" counter

$ sudo iptables-translate -A FORWARD -m helper ! --helper ftp
nft add rule ip filter FORWARD ct helper != \"ftp\" counter

Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
---
 extensions/libxt_helper.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/extensions/libxt_helper.c b/extensions/libxt_helper.c
index c9f9435..971ce4a 100644
--- a/extensions/libxt_helper.c
+++ b/extensions/libxt_helper.c
@@ -45,6 +45,17 @@ static void helper_save(const void *ip, const struct xt_entry_match *match)
 	xtables_save_string(info->name);
 }
 
+static int helper_xlate(const struct xt_entry_match *match,
+			struct xt_buf *buf, int numeric)
+{
+	const struct xt_helper_info *info = (const void *)match->data;
+
+	xt_buf_add(buf, "ct helper%s \\\"%s\\\" ",
+		   info->invert ? " !=" : "", info->name);
+
+	return 1;
+}
+
 static struct xtables_match helper_match = {
 	.family		= NFPROTO_UNSPEC,
 	.name		= "helper",
@@ -55,6 +66,7 @@ static struct xtables_match helper_match = {
 	.save		= helper_save,
 	.x6_parse	= helper_parse,
 	.x6_options	= helper_opts,
+	.xlate		= helper_xlate,
 };
 
 void _init(void)
-- 
1.9.1