bgpd, topotests: bmp, fix wrong peer distinguisher value for peer vrf…

… up/down

When running the bgp_bmp_2 vrf test, peer vrf up/down events from the pre
and post policy are received with a wrong peer distinguisher value.

> {"peer_type": "route distinguisher instance", "policy": "pre-policy",
> "ipv6": true, "peer_ip": "192:168::2", "peer_distinguisher": "0:0",
> "peer_asn": 65502, "peer_bgp_id": "192.168.0.2", "timestamp":
> "2024-10-16 21:59:53.111962", "bmp_log_type": "peer up", "local_ip":
> "192:168::1", "local_port": 179, "remote_port": 50836, "seq": 5}

RFC7854 mentions in 4.2 that if the peer is a "RD Instance Peer", it is
set to the route distinguisher of the particular instance the peer
belongs to.

Fix this by modifying the BMP client, update the peer distinguisher
value by filling the peer distinguisher in the bmp_peerstate function.

> {"peer_type": "route distinguisher instance", "policy": "pre-policy",
> "ipv6": true, "peer_ip": "192:168::2", "peer_distinguisher": "444:1",
> "peer_asn": 65502, "peer_bgp_id": "192.168.0.2", "timestamp":
> "2024-10-16 21:59:53.111962", "bmp_log_type": "peer up", "local_ip":
> "192:168::1", "local_port": 179, "remote_port": 50836, "seq": 5}

Add a test to check that peer_distinguisher value is not 0:0 when an
RD instance is set.

Signed-off-by: Philippe Guibert <[email protected]>

bgpd/bgp_bmp.c

@@ -487,9 +487,7 @@ static struct stream *bmp_peerstate(struct peer *peer, bool down)
 
 		bmp_common_hdr(s, BMP_VERSION_3,
 				BMP_TYPE_PEER_UP_NOTIFICATION);
-		bmp_per_peer_hdr(s, peer->bgp, peer, 0,
-				 BMP_PEER_TYPE_GLOBAL_INSTANCE, 0,
-				 &uptime_real);
+		bmp_per_peer_hdr(s, peer->bgp, peer, 0, peer_type, peer_distinguisher, &uptime_real);
 
 		/* Local Address (16 bytes) */
 		if (is_locrib)
@@ -551,7 +549,7 @@ static struct stream *bmp_peerstate(struct peer *peer, bool down)
 
 		bmp_common_hdr(s, BMP_VERSION_3,
 				BMP_TYPE_PEER_DOWN_NOTIFICATION);
-		bmp_per_peer_hdr(s, peer->bgp, peer, 0, peer_type, 0, &uptime_real);
+		bmp_per_peer_hdr(s, peer->bgp, peer, 0, peer_type, peer_distinguisher, &uptime_real);
 
 		type_pos = stream_get_endp(s);
 		stream_putc(s, 0);	/* placeholder for down reason */

tests/topotests/bgp_bmp/bgpbmp.py

@@ -206,6 +206,8 @@ def bmp_check_for_peer_message(
     # get the list of pairs (prefix, policy, seq) for the given message type
     peers = []
     for m in messages:
+        if is_rd_instance and m["peer_distinguisher"] == "0:0":
+            continue
         if (
             "peer_ip" in m.keys()
             and m["peer_ip"] != "0.0.0.0"