Merge pull request #17714 from opensourcerouting/fix/backport_b6dcf618777bb7a11176617d647e16ab64f49b7b_10.0

bgpd: Fix `enforce-first-as` per peer-group removal (backport)

Author: Jafaral

bgpd/bgp_vty.c

@@ -18201,7 +18201,11 @@ static void bgp_config_write_peer_global(struct vty *vty, struct bgp *bgp,
 
 	/* enforce-first-as */
 	if (CHECK_FLAG(bgp->flags, BGP_FLAG_ENFORCE_FIRST_AS)) {
-		if (!peergroup_flag_check(peer, PEER_FLAG_ENFORCE_FIRST_AS))
+		/* The `no` form is printed because by default this enforcing
+		 * is enabled, thus we need to print it inverted.
+		 * See peer_new().
+		 */
+		if (peergroup_flag_check(peer, PEER_FLAG_ENFORCE_FIRST_AS))
 			vty_out(vty, " no neighbor %s enforce-first-as\n", addr);
 	} else {
 		if (peergroup_flag_check(peer, PEER_FLAG_ENFORCE_FIRST_AS))

bgpd/bgpd.c

@@ -1564,8 +1564,13 @@ struct peer *peer_new(struct bgp *bgp)
 
 	SET_FLAG(peer->sflags, PEER_STATUS_CAPABILITY_OPEN);
 
-	if (CHECK_FLAG(bgp->flags, BGP_FLAG_ENFORCE_FIRST_AS))
-		peer_flag_set(peer, PEER_FLAG_ENFORCE_FIRST_AS);
+	/* By default this is enabled, thus we need to mark it as
+	 * inverted in order to display correctly in the configuration.
+	 */
+	if (CHECK_FLAG(bgp->flags, BGP_FLAG_ENFORCE_FIRST_AS)) {
+		SET_FLAG(peer->flags_invert, PEER_FLAG_ENFORCE_FIRST_AS);
+		SET_FLAG(peer->flags, PEER_FLAG_ENFORCE_FIRST_AS);
+	}
 
 	if (CHECK_FLAG(bgp->flags, BGP_FLAG_SOFT_VERSION_CAPABILITY))
 		peer_flag_set(peer, PEER_FLAG_CAPABILITY_SOFT_VERSION);