bgpd: Handle software version capability dynamicaly

We have dynamic capability support, but it handles only MP capability.

With this change, we can enable software version capability dynamicaly, without
resetting the session.

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>

bgpd/bgp_packet.c

@@ -1199,6 +1199,8 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 	struct stream *s;
 	iana_afi_t pkt_afi = IANA_AFI_IPV4;
 	iana_safi_t pkt_safi = IANA_SAFI_UNICAST;
+	unsigned long cap_len;
+	uint16_t len;
 
 	/* Convert AFI, SAFI to values for packet. */
 	bgp_map_afi_safi_int2iana(afi, safi, &pkt_afi, &pkt_safi);
@@ -1209,7 +1211,41 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 	bgp_packet_set_marker(s, BGP_MSG_CAPABILITY);
 
 	/* Encode MP_EXT capability. */
-	if (capability_code == CAPABILITY_CODE_MP) {
+	switch (capability_code) {
+	case CAPABILITY_CODE_SOFT_VERSION:
+		SET_FLAG(peer->cap, PEER_CAP_SOFT_VERSION_ADV);
+		stream_putc(s, action);
+		stream_putc(s, CAPABILITY_CODE_SOFT_VERSION);
+		cap_len = stream_get_endp(s);
+		stream_putc(s, 0); /* Capability Length */
+
+		/* The Capability Length SHOULD be no greater than 64.
+		 * This is the limit to allow other capabilities as much
+		 * space as they require.
+		 */
+		const char *soft_version = cmd_software_version_get();
+
+		len = strlen(soft_version);
+		if (len > BGP_MAX_SOFT_VERSION)
+			len = BGP_MAX_SOFT_VERSION;
+
+		stream_putc(s, len);
+		stream_put(s, soft_version, len);
+
+		/* 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 Software Version for afi/safi: %s/%s",
+				   peer,
+				   action == CAPABILITY_ACTION_SET
+					   ? "Advertising"
+					   : "Removing",
+				   iana_afi2str(pkt_afi),
+				   iana_safi2str(pkt_safi));
+		break;
+	case CAPABILITY_CODE_MP:
 		stream_putc(s, action);
 		stream_putc(s, CAPABILITY_CODE_MP);
 		stream_putc(s, CAPABILITY_CODE_MP_LEN);
@@ -1224,6 +1260,9 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 				action == CAPABILITY_ACTION_SET ? "Advertising"
 								: "Removing",
 				iana_afi2str(pkt_afi), iana_safi2str(pkt_safi));
+		break;
+	default:
+		break;
 	}
 
 	/* Set packet size. */
@@ -2698,6 +2737,7 @@ static int bgp_capability_msg_parse(struct peer *peer, uint8_t *pnt,
 	afi_t afi;
 	iana_safi_t pkt_safi;
 	safi_t safi;
+	char soft_version[BGP_MAX_SOFT_VERSION + 1] = {};
 
 	end = pnt + length;
 
@@ -2728,14 +2768,6 @@ static int bgp_capability_msg_parse(struct peer *peer, uint8_t *pnt,
 				"%s CAPABILITY has action: %d, code: %u, length %u",
 				peer->host, action, hdr->code, hdr->length);
 
-		if (hdr->length < sizeof(struct capability_mp_data)) {
-			zlog_info(
-				"%pBP Capability structure is not properly filled out, expected at least %zu bytes but header length specified is %d",
-				peer, sizeof(struct capability_mp_data),
-				hdr->length);
-			return BGP_Stop;
-		}
-
 		/* Capability length check. */
 		if ((pnt + hdr->length + 3) > end) {
 			zlog_info("%s Capability length error", peer->host);
@@ -2744,20 +2776,42 @@ static int bgp_capability_msg_parse(struct peer *peer, uint8_t *pnt,
 			return BGP_Stop;
 		}
 
-		/* Fetch structure to the byte stream. */
-		memcpy(&mpc, pnt + 3, sizeof(struct capability_mp_data));
-		pnt += hdr->length + 3;
+		/* Ignore capability when override-capability is set. */
+		if (CHECK_FLAG(peer->flags, PEER_FLAG_OVERRIDE_CAPABILITY))
+			continue;
 
-		/* We know MP Capability Code. */
-		if (hdr->code == CAPABILITY_CODE_MP) {
+		switch (hdr->code) {
+		case CAPABILITY_CODE_SOFT_VERSION:
+			if (action == CAPABILITY_ACTION_SET) {
+				SET_FLAG(peer->cap, PEER_CAP_SOFT_VERSION_RCV);
+
+				memcpy(&soft_version, pnt + 3, hdr->length);
+				soft_version[hdr->length] = '\0';
+
+				XFREE(MTYPE_BGP_SOFT_VERSION,
+				      peer->soft_version);
+				peer->soft_version =
+					XSTRDUP(MTYPE_BGP_SOFT_VERSION,
+						soft_version);
+			} else {
+				UNSET_FLAG(peer->cap, PEER_CAP_SOFT_VERSION_RCV);
+				XFREE(MTYPE_BGP_SOFT_VERSION,
+				      peer->soft_version);
+			}
+			break;
+		case CAPABILITY_CODE_MP:
+			if (hdr->length < sizeof(struct capability_mp_data)) {
+				zlog_info("%pBP Capability structure is not properly filled out, expected at least %zu bytes but header length specified is %d",
+					  peer,
+					  sizeof(struct capability_mp_data),
+					  hdr->length);
+				return BGP_Stop;
+			}
+
+			memcpy(&mpc, pnt + 3, sizeof(struct capability_mp_data));
 			pkt_afi = ntohs(mpc.afi);
 			pkt_safi = mpc.safi;
 
-			/* Ignore capability when override-capability is set. */
-			if (CHECK_FLAG(peer->flags,
-				       PEER_FLAG_OVERRIDE_CAPABILITY))
-				continue;
-
 			/* Convert AFI, SAFI to internal values. */
 			if (bgp_map_afi_safi_iana2int(pkt_afi, pkt_safi, &afi,
 						      &safi)) {
@@ -2797,12 +2851,16 @@ static int bgp_capability_msg_parse(struct peer *peer, uint8_t *pnt,
 				else
 					return BGP_Stop;
 			}
-		} else {
+			break;
+		default:
 			flog_warn(
 				EC_BGP_UNRECOGNIZED_CAPABILITY,
 				"%s unrecognized capability code: %d - ignored",
 				peer->host, hdr->code);
+			break;
 		}
+
+		pnt += hdr->length + 3;
 	}
 
 	/* No FSM action necessary */

bgpd/bgp_vty.c

@@ -5725,17 +5725,29 @@ DEFPY(neighbor_capability_software_version,
       "Advertise Software Version capability to the peer\n")
 {
 	struct peer *peer;
+	int ret;
 
 	peer = peer_and_group_lookup_vty(vty, neighbor);
 	if (peer && peer->conf_if)
 		return CMD_SUCCESS;
 
 	if (no)
-		return peer_flag_unset_vty(vty, neighbor,
-					   PEER_FLAG_CAPABILITY_SOFT_VERSION);
+		ret = peer_flag_unset_vty(vty, neighbor,
+					  PEER_FLAG_CAPABILITY_SOFT_VERSION);
 	else
-		return peer_flag_set_vty(vty, neighbor,
-					 PEER_FLAG_CAPABILITY_SOFT_VERSION);
+		ret = peer_flag_set_vty(vty, neighbor,
+					PEER_FLAG_CAPABILITY_SOFT_VERSION);
+
+	if (peer_established(peer)) {
+		if (CHECK_FLAG(peer->cap, PEER_CAP_DYNAMIC_RCV) &&
+		    CHECK_FLAG(peer->cap, PEER_CAP_DYNAMIC_ADV))
+			bgp_capability_send(peer, AFI_IP, SAFI_UNICAST,
+					    CAPABILITY_CODE_SOFT_VERSION,
+					    no ? CAPABILITY_ACTION_UNSET
+					       : CAPABILITY_ACTION_SET);
+	}
+
+	return ret;
 }
 
 static int peer_af_flag_modify_vty(struct vty *vty, const char *peer_str,

bgpd/bgpd.c

@@ -4449,7 +4449,7 @@ static const struct peer_flag_action peer_flag_action_list[] = {
 	{PEER_FLAG_PORT, 0, peer_change_reset},
 	{PEER_FLAG_AIGP, 0, peer_change_none},
 	{PEER_FLAG_GRACEFUL_SHUTDOWN, 0, peer_change_none},
-	{PEER_FLAG_CAPABILITY_SOFT_VERSION, 0, peer_change_reset},
+	{PEER_FLAG_CAPABILITY_SOFT_VERSION, 0, peer_change_none},
 	{0, 0, 0}};
 
 static const struct peer_flag_action peer_af_flag_action_list[] = {