[PATCH] extensions: libip6t_hl: Add translation to nft

[PATCH] extensions: libip6t_hl: Add translation to nft

[Shivani Bhardwaj]

Add translation for hop limit to nftables.

Examples:

$ sudo ip6tables-translate -t nat -A postrouting -m hl --hl-gt 3
nft add rule ip6 nat postrouting ip6 hoplimit gt 3 counter

$ sudo ip6tables-translate -t nat -A postrouting -m hl ! --hl-eq 3
nft add rule ip6 nat postrouting ip6 hoplimit != 3 counter

Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
---
 extensions/libip6t_hl.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/extensions/libip6t_hl.c b/extensions/libip6t_hl.c
index 3559db4..0e13df1 100644
--- a/extensions/libip6t_hl.c
+++ b/extensions/libip6t_hl.c
@@ -97,6 +97,23 @@ static const struct xt_option_entry hl_opts[] = {
 };
 #undef s
 
+static int hl_xlate(const struct xt_entry_match *match,
+		    struct xt_buf *buf, int numeric)
+{
+	static const char *const op[] = {
+		[IP6T_HL_EQ] = "ip6 hoplimit",
+		[IP6T_HL_NE] = "ip6 hoplimit !=",
+		[IP6T_HL_LT] = "ip6 hoplimit lt",
+		[IP6T_HL_GT] = "ip6 hoplimit gt" };
+
+	const struct ip6t_hl_info *info =
+			(struct ip6t_hl_info *) match->data;
+
+	xt_buf_add(buf, "%s %u ", op[info->mode], info->hop_limit);
+
+	return 1;
+}
+
 static struct xtables_match hl_mt6_reg = {
 	.name          = "hl",
 	.version       = XTABLES_VERSION,
@@ -109,6 +126,7 @@ static struct xtables_match hl_mt6_reg = {
 	.x6_parse      = hl_parse,
 	.x6_fcheck     = hl_check,
 	.x6_options    = hl_opts,
+	.xlate	       = hl_xlate,
 };
 
 
-- 
1.9.1

Re: [PATCH] extensions: libip6t_hl: Add translation to nft

[Pablo Neira Ayuso]

On Thu, Jan 07, 2016 at 03:09:24PM +0530, Shivani Bhardwaj wrote:
> Add translation for hop limit to nftables.
> 
> Examples:
> 
> $ sudo ip6tables-translate -t nat -A postrouting -m hl --hl-gt 3
> nft add rule ip6 nat postrouting ip6 hoplimit gt 3 counter
> 
> $ sudo ip6tables-translate -t nat -A postrouting -m hl ! --hl-eq 3
> nft add rule ip6 nat postrouting ip6 hoplimit != 3 counter
> 
> Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
> ---
>  extensions/libip6t_hl.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/extensions/libip6t_hl.c b/extensions/libip6t_hl.c
> index 3559db4..0e13df1 100644
> --- a/extensions/libip6t_hl.c
> +++ b/extensions/libip6t_hl.c
> @@ -97,6 +97,23 @@ static const struct xt_option_entry hl_opts[] = {
>  };
>  #undef s
>  
> +static int hl_xlate(const struct xt_entry_match *match,
> +		    struct xt_buf *buf, int numeric)
> +{
> +	static const char *const op[] = {
> +		[IP6T_HL_EQ] = "ip6 hoplimit",
> +		[IP6T_HL_NE] = "ip6 hoplimit !=",
> +		[IP6T_HL_LT] = "ip6 hoplimit lt",
> +		[IP6T_HL_GT] = "ip6 hoplimit gt" };

I'd suggest you use something like:

	static const char *const op[] = {
                [IP6T_HL_EQ] = "",
                [IP6T_HL_NE] = "!=",
                [IP6T_HL_LT] = "lt",
                [IP6T_HL_GT] = "gt"
        };

We can later on consolidate this code by providing a common function
from libxtables for everyone.

Thanks.