BGP: implement Adj-RIB-In

The patch implements optional internal import table to a channel and
hooks it to BGP so it can be used as Adj-RIB-In. When enabled, all
received (pre-filtered) routes are stored there and import filters can
be re-evaluated without explicit route refresh. An import table can be
examined using e.g. 'show route import table bgp1.ipv4'.

4 files changed, 20 insertions, 6 deletions

diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
index e20097ae..b2dbd780 100644
--- a/proto/bgp/bgp.c
+++ b/proto/bgp/bgp.c
@@ -545,7 +545,7 @@ bgp_conn_enter_established_state(struct bgp_conn *conn)
 
     int active = loc->ready && rem->ready;
     c->c.disabled = !active;
-    c->c.reloadable = p->route_refresh;
+    c->c.reloadable = p->route_refresh || c->cf->import_table;
 
     c->index = active ? num++ : 0;
 
@@ -838,6 +838,9 @@ bgp_refresh_begin(struct bgp_channel *c)
 
   c->load_state = BFS_REFRESHING;
   rt_refresh_begin(c->c.table, &c->c);
+
+  if (c->c.in_table)
+    rt_refresh_begin(c->c.in_table, &c->c);
 }
 
 /**
@@ -859,6 +862,9 @@ bgp_refresh_end(struct bgp_channel *c)
 
   c->load_state = BFS_NONE;
   rt_refresh_end(c->c.table, &c->c);
+
+  if (c->c.in_table)
+    rt_prune_sync(c->c.in_table, 0);
 }
 
 
@@ -1296,9 +1302,12 @@ bgp_reload_routes(struct channel *C)
   struct bgp_proto *p = (void *) C->proto;
   struct bgp_channel *c = (void *) C;
 
-  ASSERT(p->conn && p->route_refresh);
+  ASSERT(p->conn && (p->route_refresh || c->c.in_table));
 
-  bgp_schedule_packet(p->conn, c, PKT_ROUTE_REFRESH);
+  if (c->c.in_table)
+    channel_schedule_reload(C);
+  else
+    bgp_schedule_packet(p->conn, c, PKT_ROUTE_REFRESH);
 }
 
 static void
@@ -1598,6 +1607,9 @@ bgp_channel_start(struct channel *C)
   bgp_init_bucket_table(c);
   bgp_init_prefix_table(c);
 
+  if (c->cf->import_table)
+    channel_setup_in_table(C);
+
   c->stale_timer = tm_new_init(c->pool, bgp_long_lived_stale_timeout, c, 0, 0);
 
   c->next_hop_addr = c->cf->next_hop_addr;
diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index e1ff013a..76b835fa 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -144,6 +144,7 @@ struct bgp_channel_config {
   uint llgr_time;			/* Long-lived graceful restart stale time */
   u8 ext_next_hop;			/* Allow both IPv4 and IPv6 next hops */
   u8 add_path;				/* Use ADD-PATH extension [RFC 7911] */
+  u8 import_table;			/* Use c.in_table as Adj-RIB-In */
 
   uint rest[0];				/* Remaining items are reconfigured separately */
   struct rtable_config *igp_table_ip4;	/* Table for recursive IPv4 next hop lookups */
diff --git a/proto/bgp/config.Y b/proto/bgp/config.Y
index 120b1e88..f155eee2 100644
--- a/proto/bgp/config.Y
+++ b/proto/bgp/config.Y
@@ -29,7 +29,7 @@ CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY, KEEPALIVE,
 	SECURITY, DETERMINISTIC, SECONDARY, ALLOW, BFD, ADD, PATHS, RX, TX,
 	GRACEFUL, RESTART, AWARE, CHECK, LINK, PORT, EXTENDED, MESSAGES, SETKEY,
 	STRICT, BIND, CONFEDERATION, MEMBER, MULTICAST, FLOW4, FLOW6, LONG,
-	LIVED, STALE)
+	LIVED, STALE, IMPORT)
 
 %type <i32> bgp_afi
 
@@ -229,6 +229,7 @@ bgp_channel_item:
  | ADD PATHS RX { BGP_CC->add_path = BGP_ADD_PATH_RX; }
  | ADD PATHS TX { BGP_CC->add_path = BGP_ADD_PATH_TX; }
  | ADD PATHS bool { BGP_CC->add_path = $3 ? BGP_ADD_PATH_FULL : 0; }
+ | IMPORT TABLE bool { BGP_CC->import_table = $3; }
  | IGP TABLE rtable {
     if (BGP_CC->desc->no_igp)
       cf_error("IGP table not allowed here");
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index 3be48c00..c2261870 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -1159,7 +1159,7 @@ bgp_rte_update(struct bgp_parse_state *s, net_addr *n, u32 path_id, rta *a0)
   if (!a0)
   {
     /* Route withdraw */
-    rte_update2(&s->channel->c, n, NULL, s->last_src);
+    rte_update3(&s->channel->c, n, NULL, s->last_src);
     return;
   }
 
@@ -1180,7 +1180,7 @@ bgp_rte_update(struct bgp_parse_state *s, net_addr *n, u32 path_id, rta *a0)
   e->pflags = 0;
   e->u.bgp.suppressed = 0;
   e->u.bgp.stale = -1;
-  rte_update2(&s->channel->c, n, e, s->last_src);
+  rte_update3(&s->channel->c, n, e, s->last_src);
 }
 
 static void