3 files changed, 80 insertions, 15 deletions

diff --git a/src/vnet/gre/gre.c b/src/vnet/gre/gre.c
index f06f19fab2a..2b95d99148a 100644
--- a/src/vnet/gre/gre.c
+++ b/src/vnet/gre/gre.c
@@ -18,7 +18,6 @@
 #include <vnet/vnet.h>
 #include <vnet/gre/gre.h>
 #include <vnet/adj/adj_midchain.h>
-#include <vnet/nhrp/nhrp.h>
 
 extern gre_main_t gre_main;
 
@@ -331,10 +330,38 @@ gre_update_adj (vnet_main_t * vnm, u32 sw_if_index, adj_index_t ai)
   gre_tunnel_stack (ai);
 }
 
-static adj_walk_rc_t
-mgre_mk_complete_walk (adj_index_t ai, void *ctx)
+adj_walk_rc_t
+mgre_mk_complete_walk (adj_index_t ai, void *data)
 {
-  nhrp_entry_adj_stack (ctx, ai);
+  mgre_walk_ctx_t *ctx = data;
+  adj_midchain_fixup_t f;
+
+  f = (ctx->t->tunnel_dst.fp_proto == FIB_PROTOCOL_IP4 ?
+       gre4_fixup : gre6_fixup);
+
+  adj_nbr_midchain_update_rewrite
+    (ai, f, NULL, ADJ_FLAG_MIDCHAIN_IP_STACK,
+     gre_build_rewrite (vnet_get_main (),
+			ctx->t->sw_if_index,
+			adj_get_link_type (ai),
+			&nhrp_entry_get_nh (ctx->ne)->fp_addr));
+
+  nhrp_entry_adj_stack (ctx->ne, ai);
+
+  return (ADJ_WALK_RC_CONTINUE);
+}
+
+adj_walk_rc_t
+mgre_mk_incomplete_walk (adj_index_t ai, void *data)
+{
+  gre_tunnel_t *t = data;
+  adj_midchain_fixup_t f;
+
+  f = (t->tunnel_dst.fp_proto == FIB_PROTOCOL_IP4 ? gre4_fixup : gre6_fixup);
+
+  adj_nbr_midchain_update_rewrite (ai, f, NULL, ADJ_FLAG_NONE, NULL);
+
+  adj_midchain_delegate_unstack (ai);
 
   return (ADJ_WALK_RC_CONTINUE);
 }
@@ -346,20 +373,11 @@ mgre_update_adj (vnet_main_t * vnm, u32 sw_if_index, adj_index_t ai)
   ip_adjacency_t *adj;
   nhrp_entry_t *ne;
   gre_tunnel_t *t;
-  adj_flags_t af;
-  u8 is_ipv6;
   u32 ti;
 
   adj = adj_get (ai);
   ti = gm->tunnel_index_by_sw_if_index[sw_if_index];
   t = pool_elt_at_index (gm->tunnels, ti);
-  is_ipv6 = t->tunnel_dst.fp_proto == FIB_PROTOCOL_IP6 ? 1 : 0;
-  af = ADJ_FLAG_MIDCHAIN_IP_STACK;
-
-  adj_nbr_midchain_update_rewrite
-    (ai, !is_ipv6 ? gre4_fixup : gre6_fixup, NULL, af,
-     gre_build_rewrite (vnm, sw_if_index, adj_get_link_type (ai),
-			&adj->sub_type.nbr.next_hop));
 
   ne = nhrp_entry_find (sw_if_index, &adj->sub_type.nbr.next_hop);
 
@@ -367,8 +385,13 @@ mgre_update_adj (vnet_main_t * vnm, u32 sw_if_index, adj_index_t ai)
     // no NHRP entry to provide the next-hop
     return;
 
-  adj_nbr_walk_nh (sw_if_index, t->tunnel_dst.fp_proto,
-		   &adj->sub_type.nbr.next_hop, mgre_mk_complete_walk, ne);
+  mgre_walk_ctx_t ctx = {
+    .t = t,
+    .ne = ne
+  };
+  adj_nbr_walk_nh (sw_if_index,
+		   adj->ia_nh_proto,
+		   &adj->sub_type.nbr.next_hop, mgre_mk_complete_walk, &ctx);
 }
 #endif /* CLIB_MARCH_VARIANT */
 
diff --git a/src/vnet/gre/gre.h b/src/vnet/gre/gre.h
index 7f6ff0be9dc..70f624122ce 100644
--- a/src/vnet/gre/gre.h
+++ b/src/vnet/gre/gre.h
@@ -25,6 +25,7 @@
 #include <vnet/ip/format.h>
 #include <vnet/adj/adj_types.h>
 #include <vnet/tunnel/tunnel.h>
+#include <vnet/nhrp/nhrp.h>
 
 extern vnet_hw_interface_class_t gre_hw_interface_class;
 extern vnet_hw_interface_class_t mgre_hw_interface_class;
@@ -323,6 +324,15 @@ extern void gre_tunnel_stack (adj_index_t ai);
 extern void gre_update_adj (vnet_main_t * vnm,
 			    u32 sw_if_index, adj_index_t ai);
 
+typedef struct mgre_walk_ctx_t_
+{
+  const gre_tunnel_t *t;
+  const nhrp_entry_t *ne;
+} mgre_walk_ctx_t;
+
+adj_walk_rc_t mgre_mk_complete_walk (adj_index_t ai, void *data);
+adj_walk_rc_t mgre_mk_incomplete_walk (adj_index_t ai, void *data);
+
 format_function_t format_gre_protocol;
 format_function_t format_gre_header;
 format_function_t format_gre_header_with_length;
diff --git a/src/vnet/gre/interface.c b/src/vnet/gre/interface.c
index 59bf21d6dc2..178b080a73b 100644
--- a/src/vnet/gre/interface.c
+++ b/src/vnet/gre/interface.c
@@ -203,10 +203,14 @@ gre_nhrp_mk_key (const gre_tunnel_t * t,
 		 t->type, TUNNEL_MODE_P2P, 0, &key->gtk_v6);
 }
 
+/**
+ * An NHRP entry has been added
+ */
 static void
 gre_nhrp_entry_added (const nhrp_entry_t * ne)
 {
   gre_main_t *gm = &gre_main;
+  const ip46_address_t *nh;
   gre_tunnel_key_t key;
   gre_tunnel_t *t;
   u32 sw_if_index;
@@ -221,16 +225,35 @@ gre_nhrp_entry_added (const nhrp_entry_t * ne)
   if (INDEX_INVALID == t_idx)
     return;
 
+  /* entry has been added on an interface for which there is a GRE tunnel */
   t = pool_elt_at_index (gm->tunnels, t_idx);
 
+  if (t->mode != TUNNEL_MODE_MP)
+    return;
+
+  /* the next-hop (underlay) of the NHRP entry will form part of the key for
+   * ingress lookup to match packets to this interface */
   gre_nhrp_mk_key (t, ne, &key);
   gre_tunnel_db_add (t, &key);
+
+  /* update the rewrites for each of the adjacencies for this peer (overlay)
+   * using  the next-hop (underlay) */
+  mgre_walk_ctx_t ctx = {
+    .t = t,
+    .ne = ne
+  };
+  nh = nhrp_entry_get_peer (ne);
+  adj_nbr_walk_nh (nhrp_entry_get_sw_if_index (ne),
+		   (ip46_address_is_ip4 (nh) ?
+		    FIB_PROTOCOL_IP4 :
+		    FIB_PROTOCOL_IP6), nh, mgre_mk_complete_walk, &ctx);
 }
 
 static void
 gre_nhrp_entry_deleted (const nhrp_entry_t * ne)
 {
   gre_main_t *gm = &gre_main;
+  const ip46_address_t *nh;
   gre_tunnel_key_t key;
   gre_tunnel_t *t;
   u32 sw_if_index;
@@ -247,8 +270,17 @@ gre_nhrp_entry_deleted (const nhrp_entry_t * ne)
 
   t = pool_elt_at_index (gm->tunnels, t_idx);
 
+  /* remove the next-hop as an ingress lookup key */
   gre_nhrp_mk_key (t, ne, &key);
   gre_tunnel_db_remove (t, &key);
+
+  nh = nhrp_entry_get_peer (ne);
+
+  /* make all the adjacencies incomplete */
+  adj_nbr_walk_nh (nhrp_entry_get_sw_if_index (ne),
+		   (ip46_address_is_ip4 (nh) ?
+		    FIB_PROTOCOL_IP4 :
+		    FIB_PROTOCOL_IP6), nh, mgre_mk_incomplete_walk, t);
 }
 
 static walk_rc_t