nhrp: Preserve mtu during interface up/down and tunnel source change

preserve mtu upon interface flapping and tunnel source change.

Signed-off-by:Reuben Dowle <reuben.dowle@4rf.com>
Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

5 files changed, 30 insertions, 5 deletions

diff --git a/nhrpd/nhrp_route.c b/nhrpd/nhrp_route.c
index 1f513b7c0..ee8db277d 100644
--- a/nhrpd/nhrp_route.c
+++ b/nhrpd/nhrp_route.c
@@ -435,6 +435,7 @@ void nhrp_send_zebra_gre_source_set(struct interface *ifp,
 	stream_putl(s, ifp->ifindex);
 	stream_putl(s, link_idx);
 	stream_putl(s, link_vrf_id);
+	stream_putl(s, 0); /* mtu provisioning */
 	stream_putw_at(s, 0, stream_get_endp(s));
 	zclient_send_message(zclient);
 }
diff --git a/zebra/if_netlink.c b/zebra/if_netlink.c
index 44ee8d946..1886f7a54 100644
--- a/zebra/if_netlink.c
+++ b/zebra/if_netlink.c
@@ -473,6 +473,7 @@ netlink_gre_set_msg_encoder(struct zebra_dplane_ctx *ctx, void *buf,
 		char buf[];
 	} *req = buf;
 	uint32_t link_idx;
+	unsigned int mtu;
 	struct rtattr *rta_info, *rta_data;
 
 	if (buflen < sizeof(*req))
@@ -486,6 +487,10 @@ netlink_gre_set_msg_encoder(struct zebra_dplane_ctx *ctx, void *buf,
 	req->ifi.ifi_index = dplane_ctx_get_ifindex(ctx);
 	req->ifi.ifi_change = 0xFFFFFFFF;
 	link_idx = dplane_ctx_gre_get_link_ifindex(ctx);
+	mtu = dplane_ctx_gre_get_mtu(ctx);
+
+	if (mtu && !nl_attr_put32(&req->n, buflen, IFLA_MTU, mtu))
+		return 0;
 
 	rta_info = nl_attr_nest(&req->n, buflen, IFLA_LINKINFO);
 	if (!rta_info)
diff --git a/zebra/zapi_msg.c b/zebra/zapi_msg.c
index 22a6bf496..75e2f59b9 100644
--- a/zebra/zapi_msg.c
+++ b/zebra/zapi_msg.c
@@ -3438,12 +3438,14 @@ static inline void zebra_gre_source_set(ZAPI_HANDLER_ARGS)
 	vrf_id_t vrf_id = zvrf->vrf->vrf_id;
 	struct zebra_if *zif, *gre_zif;
 	struct zebra_l2info_gre *gre_info;
+	unsigned int mtu;
 
 	s = msg;
 	STREAM_GETL(s, idx);
 	ifp  = if_lookup_by_index(idx, vrf_id);
 	STREAM_GETL(s, link_idx);
 	STREAM_GETL(s, link_vrf_id);
+	STREAM_GETL(s, mtu);
 
 	ifp_link  = if_lookup_by_index(link_idx, link_vrf_id);
 	if (!ifp_link || !ifp) {
@@ -3464,11 +3466,14 @@ static inline void zebra_gre_source_set(ZAPI_HANDLER_ARGS)
 	if (!gre_info)
 		return;
 
-	/* if gre link already set */
-	if (gre_zif->link && gre_zif->link == ifp_link)
+	if (!mtu)
+		mtu = ifp->mtu;
+
+	/* if gre link already set or mtu did not change, do not set it */
+	if (gre_zif->link && gre_zif->link == ifp_link && mtu == ifp->mtu)
 		return;
 
-	dplane_gre_set(ifp, ifp_link);
+	dplane_gre_set(ifp, ifp_link, mtu);
 
  stream_failure:
 	return;
diff --git a/zebra/zebra_dplane.c b/zebra/zebra_dplane.c
index 565ab821d..b54973a94 100644
--- a/zebra/zebra_dplane.c
+++ b/zebra/zebra_dplane.c
@@ -273,6 +273,7 @@ struct dplane_rule_info {
 
 struct dplane_gre_ctx {
 	uint32_t link_ifindex;
+	unsigned int mtu;
 };
 /*
  * The context block used to exchange info about route updates across
@@ -1795,6 +1796,14 @@ dplane_ctx_gre_get_link_ifindex(const struct zebra_dplane_ctx *ctx)
 	return ctx->u.gre.link_ifindex;
 }
 
+unsigned int
+dplane_ctx_gre_get_mtu(const struct zebra_dplane_ctx *ctx)
+{
+	DPLANE_CTX_VALID(ctx);
+
+	return ctx->u.gre.mtu;
+}
+
 /* Accessors for PBR rule information */
 int dplane_ctx_rule_get_sock(const struct zebra_dplane_ctx *ctx)
 {
@@ -4152,7 +4161,7 @@ dplane_pbr_ipset_entry_delete(struct zebra_pbr_ipset_entry *ipset)
  * Common helper api for GRE set
  */
 enum zebra_dplane_result
-dplane_gre_set(struct interface *ifp, struct interface *ifp_link)
+dplane_gre_set(struct interface *ifp, struct interface *ifp_link, unsigned int mtu)
 {
 	enum zebra_dplane_result result = ZEBRA_DPLANE_REQUEST_FAILURE;
 	struct zebra_dplane_ctx *ctx;
@@ -4187,6 +4196,8 @@ dplane_gre_set(struct interface *ifp, struct interface *ifp_link)
 	else
 		ctx->u.gre.link_ifindex = 0;
 
+	ctx->u.gre.mtu = mtu;
+
 	ctx->zd_status = ZEBRA_DPLANE_REQUEST_SUCCESS;
 
 	/* Enqueue context for processing */
diff --git a/zebra/zebra_dplane.h b/zebra/zebra_dplane.h
index 5df58e6e9..5405a7cb8 100644
--- a/zebra/zebra_dplane.h
+++ b/zebra/zebra_dplane.h
@@ -531,6 +531,8 @@ dplane_ctx_neightable_get_ucast_probes(const struct zebra_dplane_ctx *ctx);
 /* Accessor for GRE set */
 uint32_t
 dplane_ctx_gre_get_link_ifindex(const struct zebra_dplane_ctx *ctx);
+unsigned int
+dplane_ctx_gre_get_mtu(const struct zebra_dplane_ctx *ctx);
 
 /* Namespace info - esp. for netlink communication */
 const struct zebra_dplane_info *dplane_ctx_get_ns(
@@ -704,7 +706,8 @@ enum zebra_dplane_result dplane_neigh_table_update(const struct interface *ifp,
  * Enqueue a GRE set
  */
 enum zebra_dplane_result
-dplane_gre_set(struct interface *ifp, struct interface *ifp_link);
+dplane_gre_set(struct interface *ifp, struct interface *ifp_link,
+	       unsigned int mtu);
 
 /* Forward ref of zebra_pbr_rule */
 struct zebra_pbr_rule;