rt: add path mtu support

Only use case is to allow similar behaviour to iptables
TCPMSS --clamp-mss-to-pmtu, by combining this with exthdr statement:

tcp option maxseg size set rt mtu

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/rt.c b/src/rt.c
index cd2d5a4e..91be5a11 100644
--- a/src/rt.c
+++ b/src/rt.c
@@ -73,6 +73,11 @@ static const struct rt_template rt_templates[] = {
 					      16 * BITS_PER_BYTE,
 					      BYTEORDER_BIG_ENDIAN,
 					      true),
+	[NFT_RT_TCPMSS]		= RT_TEMPLATE("mtu",
+					      &integer_type,
+					      2 * BITS_PER_BYTE,
+					      BYTEORDER_HOST_ENDIAN,
+					      false),
 };
 
 static void rt_expr_print(const struct expr *expr, struct output_ctx *octx)