Merge pull request FRRouting#14285 from opensourcerouting/feature/gra…

…ceful_restart_dynamic_capability

bgpd: Handle Graceful Restart capability using dynamic capabilities

bgpd/bgp_packet.c

@@ -1201,6 +1201,7 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 	iana_safi_t pkt_safi = IANA_SAFI_UNICAST;
 	unsigned long cap_len;
 	uint16_t len;
+	uint32_t gr_restart_time;
 
 	if (!peer_established(peer))
 		return;
@@ -1268,9 +1269,64 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 								: "Removing",
 				iana_afi2str(pkt_afi), iana_safi2str(pkt_safi));
 		break;
+	case CAPABILITY_CODE_RESTART:
+		if (!CHECK_FLAG(peer->flags, PEER_FLAG_GRACEFUL_RESTART) &&
+		    !CHECK_FLAG(peer->flags, PEER_FLAG_GRACEFUL_RESTART_HELPER))
+			return;
+
+		SET_FLAG(peer->cap, PEER_CAP_RESTART_ADV);
+		stream_putc(s, action);
+		stream_putc(s, CAPABILITY_CODE_RESTART);
+		cap_len = stream_get_endp(s);
+		stream_putc(s, 0);
+		gr_restart_time = peer->bgp->restart_time;
+
+		if (peer->bgp->t_startup) {
+			SET_FLAG(gr_restart_time, GRACEFUL_RESTART_R_BIT);
+			SET_FLAG(peer->cap, PEER_CAP_GRACEFUL_RESTART_R_BIT_ADV);
+		}
+
+		if (CHECK_FLAG(peer->bgp->flags,
+			       BGP_FLAG_GRACEFUL_NOTIFICATION)) {
+			SET_FLAG(gr_restart_time, GRACEFUL_RESTART_N_BIT);
+			SET_FLAG(peer->cap, PEER_CAP_GRACEFUL_RESTART_N_BIT_ADV);
+		}
+
+		stream_putw(s, gr_restart_time);
+
+		if (CHECK_FLAG(peer->flags, PEER_FLAG_GRACEFUL_RESTART)) {
+			FOREACH_AFI_SAFI (afi, safi) {
+				if (!peer->afc[afi][safi])
+					continue;
+
+				bgp_map_afi_safi_int2iana(afi, safi, &pkt_afi,
+							  &pkt_safi);
+				stream_putw(s, pkt_afi);
+				stream_putc(s, pkt_safi);
+				if (CHECK_FLAG(peer->bgp->flags,
+					       BGP_FLAG_GR_PRESERVE_FWD))
+					stream_putc(s, GRACEFUL_RESTART_F_BIT);
+				else
+					stream_putc(s, 0);
+			}
+		}
+
+		/* Software Version capability Len. */
+		len = stream_get_endp(s) - cap_len - 1;
+		stream_putc_at(s, cap_len, len);
+
+		if (bgp_debug_neighbor_events(peer))
+			zlog_debug("%pBP sending CAPABILITY has %s Graceful-Restart CAP for afi/safi: %s/%s",
+				   peer,
+				   action == CAPABILITY_ACTION_SET
+					   ? "Advertising"
+					   : "Removing",
+				   iana_afi2str(pkt_afi),
+				   iana_safi2str(pkt_safi));
+
+		break;
 	case CAPABILITY_CODE_REFRESH:
 	case CAPABILITY_CODE_ORF:
-	case CAPABILITY_CODE_RESTART:
 	case CAPABILITY_CODE_AS4:
 	case CAPABILITY_CODE_DYNAMIC:
 	case CAPABILITY_CODE_ADDPATH:
@@ -2753,6 +2809,93 @@ static int bgp_route_refresh_receive(struct peer *peer, bgp_size_t size)
 	return BGP_PACKET_NOOP;
 }
 
+static void bgp_dynamic_capability_graceful_restart(uint8_t *pnt, int action,
+						    struct capability_header *hdr,
+						    struct peer *peer)
+{
+#define GRACEFUL_RESTART_CAPABILITY_PER_AFI_SAFI_SIZE 4
+	uint16_t gr_restart_flag_time;
+	uint8_t *data = pnt + 3;
+	uint8_t *end = pnt + hdr->length;
+	size_t len = end - data;
+
+	if (action == CAPABILITY_ACTION_SET) {
+		if (len < sizeof(gr_restart_flag_time)) {
+			zlog_err("%pBP: Received invalid Graceful-Restart capability length %d",
+				 peer, hdr->length);
+			return;
+		}
+
+		SET_FLAG(peer->cap, PEER_CAP_RESTART_RCV);
+		ptr_get_be16(data, &gr_restart_flag_time);
+		data += sizeof(gr_restart_flag_time);
+
+		if (CHECK_FLAG(gr_restart_flag_time, GRACEFUL_RESTART_R_BIT))
+			SET_FLAG(peer->cap, PEER_CAP_GRACEFUL_RESTART_R_BIT_RCV);
+		else
+			UNSET_FLAG(peer->cap,
+				   PEER_CAP_GRACEFUL_RESTART_R_BIT_RCV);
+
+		if (CHECK_FLAG(gr_restart_flag_time, GRACEFUL_RESTART_N_BIT))
+			SET_FLAG(peer->cap, PEER_CAP_GRACEFUL_RESTART_N_BIT_RCV);
+		else
+			UNSET_FLAG(peer->cap,
+				   PEER_CAP_GRACEFUL_RESTART_N_BIT_RCV);
+
+		UNSET_FLAG(gr_restart_flag_time, 0xF000);
+		peer->v_gr_restart = gr_restart_flag_time;
+
+		while (data + GRACEFUL_RESTART_CAPABILITY_PER_AFI_SAFI_SIZE <=
+		       end) {
+			afi_t afi;
+			safi_t safi;
+			iana_afi_t pkt_afi;
+			iana_safi_t pkt_safi;
+			struct graceful_restart_af graf;
+
+			memcpy(&graf, data, sizeof(graf));
+			pkt_afi = ntohs(graf.afi);
+			pkt_safi = safi_int2iana(graf.safi);
+
+			/* Convert AFI, SAFI to internal values, check. */
+			if (bgp_map_afi_safi_iana2int(pkt_afi, pkt_safi, &afi,
+						      &safi)) {
+				if (bgp_debug_neighbor_events(peer))
+					zlog_debug("%pBP: Addr-family %s/%s(afi/safi) not supported. Ignore the Graceful Restart capability for this AFI/SAFI",
+						   peer, iana_afi2str(pkt_afi),
+						   iana_safi2str(pkt_safi));
+			} else if (!peer->afc[afi][safi]) {
+				if (bgp_debug_neighbor_events(peer))
+					zlog_debug("%pBP: Addr-family %s/%s(afi/safi) not enabled. Ignore the Graceful Restart capability",
+						   peer, iana_afi2str(pkt_afi),
+						   iana_safi2str(pkt_safi));
+			} else {
+				if (bgp_debug_neighbor_events(peer))
+					zlog_debug("%pBP: Address family %s is%spreserved",
+						   peer,
+						   get_afi_safi_str(afi, safi,
+								    false),
+						   CHECK_FLAG(peer->af_cap[afi]
+									  [safi],
+							      PEER_CAP_RESTART_AF_PRESERVE_RCV)
+							   ? " "
+							   : " not ");
+
+				SET_FLAG(peer->af_cap[afi][safi],
+					 PEER_CAP_RESTART_AF_RCV);
+				if (CHECK_FLAG(graf.flag,
+					       GRACEFUL_RESTART_F_BIT))
+					SET_FLAG(peer->af_cap[afi][safi],
+						 PEER_CAP_RESTART_AF_PRESERVE_RCV);
+			}
+
+			data += GRACEFUL_RESTART_CAPABILITY_PER_AFI_SAFI_SIZE;
+		}
+	} else {
+		UNSET_FLAG(peer->cap, PEER_CAP_RESTART_RCV);
+	}
+}
+
 /**
  * Parse BGP CAPABILITY message for peer.
  *
@@ -2886,9 +3029,20 @@ static int bgp_capability_msg_parse(struct peer *peer, uint8_t *pnt,
 					return BGP_Stop;
 			}
 			break;
+		case CAPABILITY_CODE_RESTART:
+			if ((hdr->length - 2) % 4) {
+				zlog_err("%pBP: Received invalid Graceful-Restart capability length %d",
+					 peer, hdr->length);
+				bgp_notify_send(peer, BGP_NOTIFY_CEASE,
+						BGP_NOTIFY_SUBCODE_UNSPECIFIC);
+				return BGP_Stop;
+			}
+
+			bgp_dynamic_capability_graceful_restart(pnt, action,
+								hdr, peer);
+			break;
 		case CAPABILITY_CODE_REFRESH:
 		case CAPABILITY_CODE_ORF:
-		case CAPABILITY_CODE_RESTART:
 		case CAPABILITY_CODE_AS4:
 		case CAPABILITY_CODE_DYNAMIC:
 		case CAPABILITY_CODE_ADDPATH:

bgpd/bgp_vty.c

@@ -3066,9 +3066,17 @@ DEFUN (bgp_graceful_restart_restart_time,
 	VTY_DECLVAR_CONTEXT(bgp, bgp);
 	int idx_number = 3;
 	uint32_t restart;
+	struct listnode *node, *nnode;
+	struct peer *peer;
 
 	restart = strtoul(argv[idx_number]->arg, NULL, 10);
 	bgp->restart_time = restart;
+
+	for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer))
+		bgp_capability_send(peer, AFI_IP, SAFI_UNICAST,
+				    CAPABILITY_CODE_RESTART,
+				    CAPABILITY_ACTION_SET);
+
 	return CMD_SUCCESS;
 }
 
@@ -3119,8 +3127,16 @@ DEFUN (no_bgp_graceful_restart_restart_time,
 	"Delay value (seconds)\n")
 {
 	VTY_DECLVAR_CONTEXT(bgp, bgp);
+	struct listnode *node, *nnode;
+	struct peer *peer;
 
 	bgp->restart_time = BGP_DEFAULT_RESTART_TIME;
+
+	for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer))
+		bgp_capability_send(peer, AFI_IP, SAFI_UNICAST,
+				    CAPABILITY_CODE_RESTART,
+				    CAPABILITY_ACTION_UNSET);
+
 	return CMD_SUCCESS;
 }
 
@@ -3175,12 +3191,19 @@ DEFPY (bgp_graceful_restart_notification,
 	"Indicate Graceful Restart support for BGP NOTIFICATION messages\n")
 {
 	VTY_DECLVAR_CONTEXT(bgp, bgp);
+	struct listnode *node, *nnode;
+	struct peer *peer;
 
 	if (no)
 		UNSET_FLAG(bgp->flags, BGP_FLAG_GRACEFUL_NOTIFICATION);
 	else
 		SET_FLAG(bgp->flags, BGP_FLAG_GRACEFUL_NOTIFICATION);
 
+	for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer))
+		bgp_capability_send(peer, AFI_IP, SAFI_UNICAST,
+				    CAPABILITY_CODE_RESTART,
+				    CAPABILITY_ACTION_SET);
+
 	return CMD_SUCCESS;
 }
 

doc/user/bgp.rst

@@ -840,7 +840,10 @@ The following functionality is provided by graceful restart:
 1. The feature allows the restarting router to indicate to the helping peer the
    routes it can preserve in its forwarding plane during control plane restart
    by sending graceful restart capability in the OPEN message sent during
-   session establishment.
+   session establishment. Graceful restart notification flag and/or restart
+   time can also be changed during the dynamic BGP capabilities. If using
+   dynamic capabilities, no session reset is required, thus it's very useful
+   to increase restart time before doing a software upgrade or so.
 2. The feature allows helping router to advertise to all other peers the routes
    received from the restarting router which are preserved in the forwarding
    plane of the restarting router during control plane restart.
@@ -2160,8 +2163,8 @@ Using AS Path in Route Map
    Remove some AS numbers from the AS_PATH of the BGP path's NLRI. Removed AS
    numbers are conformant with the regex defined in as-path access-list  WORD.
    The no form of this command removes this set operation from the route-map.
-   
-   
+
+
 .. _bgp-communities-attribute:
 
 Communities Attribute

tests/topotests/bgp_dynamic_capability/r1/bgpd.conf

@@ -3,6 +3,7 @@
 !
 router bgp 65001
  no bgp ebgp-requires-policy
+ bgp graceful-restart
  neighbor 192.168.1.2 remote-as external
  neighbor 192.168.1.2 timers 1 3
  neighbor 192.168.1.2 timers connect 1

tests/topotests/bgp_dynamic_capability/r2/bgpd.conf

@@ -2,6 +2,7 @@
 !debug bgp neighbor
 !
 router bgp 65002
+ bgp graceful-restart
  no bgp ebgp-requires-policy
  neighbor 192.168.1.1 remote-as external
  neighbor 192.168.1.1 timers 1 3