Implements hostcache and recursive next hops.

Hostcache is a structure for monitoring changes in a routing table that
is used for routes with dynamic/recursive next hops. This is needed for
proper iBGP next hop handling.

5 files changed, 41 insertions, 22 deletions

diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index c1b8fd1..8743358 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -1265,15 +1265,13 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin
   ea_list *ea;
   struct adata *ad;
 
+  bzero(a, sizeof(rta));
   a->proto = &bgp->p;
   a->source = RTS_BGP;
   a->scope = SCOPE_UNIVERSE;
   a->cast = RTC_UNICAST;
-  a->dest = RTD_ROUTER;
-  a->flags = 0;
-  a->aflags = 0;
+  /* a->dest = RTD_ROUTER;  -- set in bgp_set_next_hop() */
   a->from = bgp->cf->remote_ip;
-  a->eattrs = NULL;
 
   /* Parse the attributes */
   bzero(seen, sizeof(seen));
diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
index 932c8aa..b36c4a3 100644
--- a/proto/bgp/bgp.c
+++ b/proto/bgp/bgp.c
@@ -786,6 +786,8 @@ bgp_start(struct proto *P)
   p->incoming_conn.state = BS_IDLE;
   p->neigh = NULL;
 
+  rt_lock_table(p->igp_table);
+
   p->event = ev_new(p->p.pool);
   p->event->hook = bgp_decision;
   p->event->data = p;
@@ -837,6 +839,19 @@ bgp_shutdown(struct proto *P)
   return p->p.proto_state;
 }
 
+static void
+bgp_cleanup(struct proto *P)
+{
+  struct bgp_proto *p = (struct bgp_proto *) P;
+  rt_unlock_table(p->igp_table);
+}
+
+static rtable *
+get_igp_table(struct bgp_config *cf)
+{
+  return cf->igp_table ? cf->igp_table->table : cf->c.table->table;
+}
+
 static struct proto *
 bgp_init(struct proto_config *C)
 {
@@ -854,6 +869,7 @@ bgp_init(struct proto_config *C)
   p->local_as = c->local_as;
   p->remote_as = c->remote_as;
   p->is_internal = (c->local_as == c->remote_as);
+  p->igp_table = get_igp_table(c);
   return P;
 }
 
@@ -1065,7 +1081,8 @@ bgp_reconfigure(struct proto *P, struct proto_config *C)
 		     // password item is last and must be checked separately
 		     OFFSETOF(struct bgp_config, password) - sizeof(struct proto_config))
     && ((!old->password && !new->password)
-	|| (old->password && new->password && !strcmp(old->password, new->password)));
+	|| (old->password && new->password && !strcmp(old->password, new->password)))
+    && (get_igp_table(old) == get_igp_table(new));
 
   /* We should update our copy of configuration ptr as old configuration will be freed */
   if (same)
@@ -1081,6 +1098,7 @@ struct protocol proto_bgp = {
   init:			bgp_init,
   start:		bgp_start,
   shutdown:		bgp_shutdown,
+  cleanup:		bgp_cleanup,
   reconfigure:		bgp_reconfigure,
   get_status:		bgp_get_status,
   get_attr:		bgp_get_attr,
diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index c81fe62..76844af 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -47,6 +47,7 @@ struct bgp_config {
   unsigned error_delay_time_max;
   unsigned disable_after_error;		/* Disable the protocol when error is detected */
   char *password;			/* Password used for MD5 authentication */
+  struct rtable_config *igp_table;	/* Table used for recursive next hop lookups */
 };
 
 #define MLL_SELF 1
@@ -92,6 +93,7 @@ struct bgp_proto {
   struct neighbor *neigh;		/* Neighbor entry corresponding to next_hop */
   ip_addr local_addr;			/* Address of the local end of the link to next_hop */
   ip_addr source_addr;			/* Address used as advertised next hop, usually local_addr */
+  rtable *igp_table;			/* Table used for recursive next hop lookups */
   struct event *event;			/* Event for respawning and shutting process */
   struct timer *startup_timer;		/* Timer used to delay protocol startup due to previous errors (startup_delay) */
   struct bgp_bucket **bucket_hash;	/* Hash table of attribute buckets */
diff --git a/proto/bgp/config.Y b/proto/bgp/config.Y
index c4ed103..a46431c 100644
--- a/proto/bgp/config.Y
+++ b/proto/bgp/config.Y
@@ -24,7 +24,7 @@ CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY, KEEPALIVE,
 	PASSWORD, RR, RS, CLIENT, CLUSTER, ID, AS4, ADVERTISE, IPV4,
 	CAPABILITIES, LIMIT, PASSIVE, PREFER, OLDER, MISSING, LLADDR,
 	DROP, IGNORE, ROUTE, REFRESH, INTERPRET, COMMUNITIES,
-	BGP_ORIGINATOR_ID, BGP_CLUSTER_LIST)
+	BGP_ORIGINATOR_ID, BGP_CLUSTER_LIST, IGP, TABLE)
 
 CF_GRAMMAR
 
@@ -89,6 +89,7 @@ bgp_proto:
  | bgp_proto ROUTE LIMIT expr ';' { BGP_CFG->route_limit = $4; }
  | bgp_proto PASSIVE bool ';' { BGP_CFG->passive = $3; }
  | bgp_proto INTERPRET COMMUNITIES bool ';' { BGP_CFG->interpret_communities = $4; }
+ | bgp_proto IGP TABLE rtable ';' { BGP_CFG->igp_table = $4; }
  ;
 
 CF_ADDTO(dynamic_attr, BGP_ORIGIN
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index 1e9d646..514e878 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -802,26 +802,26 @@ bgp_rx_open(struct bgp_conn *conn, byte *pkt, int len)
 } while (0)
 
 static inline int
-bgp_get_nexthop(struct bgp_proto *bgp, rta *a)
+bgp_set_next_hop(struct bgp_proto *p, rta *a)
 {
-  neighbor *neigh;
-  ip_addr nexthop;
   struct eattr *nh = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
-  ASSERT(nh);
-  nexthop = *(ip_addr *) nh->u.ptr->data;
-  neigh = neigh_find(&bgp->p, &nexthop, 0);
-  if (neigh)
+  ip_addr nexthop = *(ip_addr *) nh->u.ptr->data;
+
+  if (!p->is_internal) /* FIXME better option
+ */
     {
-      if (neigh->scope == SCOPE_HOST)
-	{
-	  DBG("BGP: Loop!\n");
-	  return 0;
-	}
+      neighbor *ng = neigh_find(&p->p, &nexthop, 0) ? : p->neigh;
+      if (ng->scope == SCOPE_HOST)
+	return 0;
+
+      a->dest = RTD_ROUTER;
+      a->gw = ng->addr;
+      a->iface = ng->iface;
+      a->hostentry = NULL;
     }
   else
-    neigh = bgp->neigh;
-  a->gw = neigh->addr;
-  a->iface = neigh->iface;
+    rta_set_recursive_next_hop(p->p.table, a, p->igp_table, &nexthop);
+
   return 1;
 }
 
@@ -853,7 +853,7 @@ bgp_do_rx_update(struct bgp_conn *conn,
     return;
 
   a0 = bgp_decode_attrs(conn, attrs, attr_len, bgp_linpool, nlri_len);
-  if (a0 && nlri_len && bgp_get_nexthop(p, a0))
+  if (a0 && nlri_len && bgp_set_next_hop(p, a0))
     {
       a = rta_lookup(a0);
       while (nlri_len)