bgpd: add [no]neighbor capability fqdn command

cisco routers are not dealing fairly whith unsupported capabilities.
When a cisco router receive an unsupported capabilities it reset the
negociation without notifying the unmatching capability as described in
RFC2842.
Cisco suggest the use of
neighbor x.x.x.x capability fqdn
to avoid the use of fqdn in open message.

this new command is to remove the use of fqdn capability in the
open message with the peer "x.x.x.x".

Link: https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/116189-problemsolution-technology-00.pdf

Signed-off-by: Francois Dumontet <francois.dumontet@6wind.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/bgpd/bgp_vty.c b/bgpd/bgp_vty.c
index 2a91715536..09f9667a9a 100644
--- a/bgpd/bgp_vty.c
+++ b/bgpd/bgp_vty.c
@@ -5735,6 +5735,30 @@ DEFUN (no_neighbor_dont_capability_negotiate,
 				   PEER_FLAG_DONT_CAPABILITY);
 }
 
+/* neighbor capability fqdn */
+DEFPY (neighbor_capability_fqdn,
+       neighbor_capability_fqdn_cmd,
+       "[no$no] neighbor <A.B.C.D|X:X::X:X|WORD>$neighbor capability fqdn",
+       NO_STR
+       NEIGHBOR_STR
+       NEIGHBOR_ADDR_STR2
+       "Advertise capability to the peer\n"
+       "Advertise fqdn capability to the peer\n")
+{
+	struct peer *peer;
+
+	peer = peer_and_group_lookup_vty(vty, neighbor);
+	if (!peer)
+		return CMD_WARNING_CONFIG_FAILED;
+
+	if (no)
+		return peer_flag_unset_vty(vty, neighbor,
+					  PEER_FLAG_CAPABILITY_FQDN);
+	else
+		return peer_flag_set_vty(vty, neighbor,
+					PEER_FLAG_CAPABILITY_FQDN);
+}
+
 /* neighbor capability extended next hop encoding */
 DEFUN (neighbor_capability_enhe,
        neighbor_capability_enhe_cmd,
@@ -18189,6 +18213,12 @@ static void bgp_config_write_peer_global(struct vty *vty, struct bgp *bgp,
 	if (peergroup_flag_check(peer, PEER_FLAG_DONT_CAPABILITY))
 		vty_out(vty, " neighbor %s dont-capability-negotiate\n", addr);
 
+	/* capability fqdn */
+	if (peergroup_flag_check(peer, PEER_FLAG_CAPABILITY_FQDN))
+		vty_out(vty,
+			" no neighbor %s capability fqdn\n",
+			addr);
+
 	/* override-capability */
 	if (peergroup_flag_check(peer, PEER_FLAG_OVERRIDE_CAPABILITY))
 		vty_out(vty, " neighbor %s override-capability\n", addr);
@@ -20525,6 +20555,9 @@ void bgp_vty_init(void)
 	install_element(BGP_NODE, &neighbor_dont_capability_negotiate_cmd);
 	install_element(BGP_NODE, &no_neighbor_dont_capability_negotiate_cmd);
 
+	/* "neighbor capability fqdn" command. */
+	install_element(BGP_NODE, &neighbor_capability_fqdn_cmd);
+
 	/* "neighbor ebgp-multihop" commands. */
 	install_element(BGP_NODE, &neighbor_ebgp_multihop_cmd);
 	install_element(BGP_NODE, &neighbor_ebgp_multihop_ttl_cmd);