Merge pull request #14540 from opensourcerouting/feature/bgpd_handle_…

…fqdn_capability_via_dynamic_capability

bgpd: Handle FQDN capability using dynamic capabilities

bgpd/bgp_packet.c

@@ -1218,6 +1218,8 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 	uint8_t number_of_orfs = 0;
 	const char *capability = lookup_msg(capcode_str, capability_code,
 					    "Unknown");
+	const char *hostname = cmd_hostname_get();
+	const char *domainname = cmd_domainname_get();
 
 	if (!peer_established(peer->connection))
 		return;
@@ -1531,11 +1533,48 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 				   capability, iana_afi2str(pkt_afi),
 				   iana_safi2str(pkt_safi));
 		break;
+	case CAPABILITY_CODE_FQDN:
+		if (hostname) {
+			SET_FLAG(peer->cap, PEER_CAP_HOSTNAME_ADV);
+			stream_putc(s, action);
+			stream_putc(s, CAPABILITY_CODE_FQDN);
+			cap_len = stream_get_endp(s);
+			stream_putc(s, 0); /* Capability Length */
+
+			len = strlen(hostname);
+			if (len > BGP_MAX_HOSTNAME)
+				len = BGP_MAX_HOSTNAME;
+
+			stream_putc(s, len);
+			stream_put(s, hostname, len);
+
+			if (domainname) {
+				len = strlen(domainname);
+				if (len > BGP_MAX_HOSTNAME)
+					len = BGP_MAX_HOSTNAME;
+
+				stream_putc(s, len);
+				stream_put(s, domainname, len);
+			} else
+				stream_putc(s, 0);
+
+			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 %s for afi/safi: %s/%s",
+					   peer,
+					   action == CAPABILITY_ACTION_SET
+						   ? "Advertising"
+						   : "Removing",
+					   capability, iana_afi2str(pkt_afi),
+					   iana_safi2str(pkt_safi));
+		}
+		break;
 	case CAPABILITY_CODE_REFRESH:
 	case CAPABILITY_CODE_AS4:
 	case CAPABILITY_CODE_DYNAMIC:
 	case CAPABILITY_CODE_ENHANCED_RR:
-	case CAPABILITY_CODE_FQDN:
 	case CAPABILITY_CODE_ENHE:
 	case CAPABILITY_CODE_EXT_MESSAGE:
 		break;
@@ -3233,6 +3272,89 @@ static void bgp_dynamic_capability_orf(uint8_t *pnt, int action,
 	}
 }
 
+static void bgp_dynamic_capability_fqdn(uint8_t *pnt, int action,
+					struct capability_header *hdr,
+					struct peer *peer)
+{
+	uint8_t *data = pnt + 3;
+	uint8_t *end = data + hdr->length;
+	char str[BGP_MAX_HOSTNAME + 1] = {};
+	uint8_t len;
+
+	if (action == CAPABILITY_ACTION_SET) {
+		/* hostname */
+		if (data + 1 > end) {
+			zlog_err("%pBP: Received invalid FQDN capability (host name length)",
+				 peer);
+			return;
+		}
+
+		len = *data;
+		if (data + len > end) {
+			zlog_err("%pBP: Received invalid FQDN capability length (host name) %d",
+				 peer, hdr->length);
+			return;
+		}
+		data++;
+
+		if (len > BGP_MAX_HOSTNAME) {
+			memcpy(&str, data, BGP_MAX_HOSTNAME);
+			str[BGP_MAX_HOSTNAME] = '\0';
+		} else if (len) {
+			memcpy(&str, data, len);
+			str[len] = '\0';
+		}
+		data += len;
+
+		if (len) {
+			str[len] = '\0';
+
+			XFREE(MTYPE_BGP_PEER_HOST, peer->hostname);
+			XFREE(MTYPE_BGP_PEER_HOST, peer->domainname);
+
+			peer->hostname = XSTRDUP(MTYPE_BGP_PEER_HOST, str);
+		}
+
+		if (data + 1 > end) {
+			zlog_err("%pBP: Received invalid FQDN capability (domain name length)",
+				 peer);
+			return;
+		}
+
+		/* domainname */
+		len = *data;
+		if (data + len > end) {
+			zlog_err("%pBP: Received invalid FQDN capability length (domain name) %d",
+				 peer, len);
+			return;
+		}
+		data++;
+
+		if (len > BGP_MAX_HOSTNAME) {
+			memcpy(&str, data, BGP_MAX_HOSTNAME);
+			str[BGP_MAX_HOSTNAME] = '\0';
+		} else if (len) {
+			memcpy(&str, data, len);
+			str[len] = '\0';
+		}
+		data += len;
+
+		if (len) {
+			str[len] = '\0';
+
+			XFREE(MTYPE_BGP_PEER_HOST, peer->domainname);
+
+			peer->domainname = XSTRDUP(MTYPE_BGP_PEER_HOST, str);
+		}
+
+		SET_FLAG(peer->cap, PEER_CAP_HOSTNAME_RCV);
+	} else {
+		UNSET_FLAG(peer->cap, PEER_CAP_HOSTNAME_RCV);
+		XFREE(MTYPE_BGP_PEER_HOST, peer->hostname);
+		XFREE(MTYPE_BGP_PEER_HOST, peer->domainname);
+	}
+}
+
 static void bgp_dynamic_capability_llgr(uint8_t *pnt, int action,
 					struct capability_header *hdr,
 					struct peer *peer)
@@ -3593,11 +3715,13 @@ static int bgp_capability_msg_parse(struct peer *peer, uint8_t *pnt,
 		case CAPABILITY_CODE_ORF:
 			bgp_dynamic_capability_orf(pnt, action, hdr, peer);
 			break;
+		case CAPABILITY_CODE_FQDN:
+			bgp_dynamic_capability_fqdn(pnt, action, hdr, peer);
+			break;
 		case CAPABILITY_CODE_REFRESH:
 		case CAPABILITY_CODE_AS4:
 		case CAPABILITY_CODE_DYNAMIC:
 		case CAPABILITY_CODE_ENHANCED_RR:
-		case CAPABILITY_CODE_FQDN:
 		case CAPABILITY_CODE_ENHE:
 		case CAPABILITY_CODE_EXT_MESSAGE:
 			break;

bgpd/bgp_vty.c

@@ -10572,7 +10572,7 @@ static int bgp_clear_prefix(struct vty *vty, const char *view_name,
 /* one clear bgp command to rule them all */
 DEFUN (clear_ip_bgp_all,
        clear_ip_bgp_all_cmd,
-       "clear [ip] bgp [<view|vrf> VIEWVRFNAME] [<ipv4|ipv6|l2vpn> [<unicast|multicast|vpn|labeled-unicast|flowspec|evpn>]] <*|A.B.C.D$neighbor|X:X::X:X$neighbor|WORD$neighbor|ASNUM|external|peer-group PGNAME> [<soft [<in|out>]|in [prefix-filter]|out|message-stats>]",
+       "clear [ip] bgp [<view|vrf> VIEWVRFNAME] [<ipv4|ipv6|l2vpn> [<unicast|multicast|vpn|labeled-unicast|flowspec|evpn>]] <*|A.B.C.D$neighbor|X:X::X:X$neighbor|WORD$neighbor|ASNUM|external|peer-group PGNAME> [<soft [<in|out>]|in [prefix-filter]|out|message-stats|capabilities>]",
        CLEAR_STR
        IP_STR
        BGP_STR
@@ -10595,7 +10595,8 @@ DEFUN (clear_ip_bgp_all,
        BGP_SOFT_IN_STR
        "Push out prefix-list ORF and do inbound soft reconfig\n"
        BGP_SOFT_OUT_STR
-       "Reset message statistics\n")
+       "Reset message statistics\n"
+       "Resend capabilities\n")
 {
 	char *vrf = NULL;
 
@@ -10652,7 +10653,7 @@ DEFUN (clear_ip_bgp_all,
 		clr_sort = clear_external;
 	}
 
-	/* [<soft [<in|out>]|in [prefix-filter]|out|message-stats>] */
+	/* [<soft [<in|out>]|in [prefix-filter]|out|message-stats|capabilities>] */
 	if (argv_find(argv, argc, "soft", &idx)) {
 		if (argv_find(argv, argc, "in", &idx)
 		    || argv_find(argv, argc, "out", &idx))
@@ -10669,6 +10670,8 @@ DEFUN (clear_ip_bgp_all,
 		clr_type = BGP_CLEAR_SOFT_OUT;
 	} else if (argv_find(argv, argc, "message-stats", &idx)) {
 		clr_type = BGP_CLEAR_MESSAGE_STATS;
+	} else if (argv_find(argv, argc, "capabilities", &idx)) {
+		clr_type = BGP_CLEAR_CAPABILITIES;
 	} else
 		clr_type = BGP_CLEAR_SOFT_NONE;
 

bgpd/bgpd.c

@@ -8046,6 +8046,16 @@ static void peer_reset_message_stats(struct peer *peer)
 	}
 }
 
+/* Helper function to resend some BGP capabilities that are uncontrolled.
+ * For instance, FQDN capability, that can't be turned off, but let's say
+ * we changed the hostname, we need to resend it.
+ */
+static void peer_clear_capabilities(struct peer *peer, afi_t afi, safi_t safi)
+{
+	bgp_capability_send(peer, afi, safi, CAPABILITY_CODE_FQDN,
+			    CAPABILITY_ACTION_SET);
+}
+
 /*
  * If peer clear is invoked in a loop for all peers on the BGP instance,
  * it may end up freeing the doppelganger, and if this was the next node
@@ -8154,6 +8164,9 @@ int peer_clear_soft(struct peer *peer, afi_t afi, safi_t safi,
 	if (stype == BGP_CLEAR_MESSAGE_STATS)
 		peer_reset_message_stats(peer);
 
+	if (stype == BGP_CLEAR_CAPABILITIES)
+		peer_clear_capabilities(peer, afi, safi);
+
 	return 0;
 }
 

bgpd/bgpd.h

@@ -2073,7 +2073,8 @@ enum bgp_clear_type {
 	BGP_CLEAR_SOFT_IN,
 	BGP_CLEAR_SOFT_BOTH,
 	BGP_CLEAR_SOFT_IN_ORF_PREFIX,
-	BGP_CLEAR_MESSAGE_STATS
+	BGP_CLEAR_MESSAGE_STATS,
+	BGP_CLEAR_CAPABILITIES,
 };
 
 /* Macros. */

doc/user/bgp.rst

@@ -3938,6 +3938,26 @@ The following are available in the top level *enable* mode:
    Clear BGP message statistics for a specified peer or for all peers,
    optionally filtered by activated address-family and sub-address-family.
 
+.. clicmd:: clear bgp [ipv4|ipv6] [unicast] PEER|\* capabilities
+
+   Clear specific BGP capabilities for a specified peer or for all peers. This
+   includes such capabilities like FQDN capability, that can't be controlled by
+   any other configuration knob.
+
+   For example, if you want to change the FQDN, you MUST reset the BGP session
+   in order to send a new FQDN capability to the peer. This command allows you
+   to resend FQDN capability without resetting the session.
+
+   .. code-block:: frr
+
+      hostname bgp-new.example.com
+      clear bgp 10.10.10.1 capabilities
+
+.. note::
+
+   Changing the hostname is possible only when connected to the specific daemon.
+   If you change the hostname via ``vtysh``, it won't be changed.
+
 The following are available in the ``router bgp`` mode:
 
 .. clicmd:: write-quanta (1-64)