bgpd: improve peer-group remote-as definitions

Problem reported that with certain sequences of defining the
remote-as on the peer-group and the members, the configuration would
become wrong, with configured remote-as settings not reflected in
the config but peers unable to come up.  This fix resolves these
inconsistencies.

Ticket: CM-19560
Signed-off-by: Don Slice <dslice@cumulusnetworks.com>

bgpd/bgp_vty.c

@@ -2846,13 +2846,11 @@ static int peer_remote_as_vty(struct vty *vty, const char *peer_str,
 	switch (ret) {
 	case BGP_ERR_PEER_GROUP_MEMBER:
 		vty_out(vty,
-			"%% Peer-group AS %u. Cannot configure remote-as for member\n",
+			"%% Peer-group member cannot override remote-as of peer-group\n");
-			as);
 		return CMD_WARNING_CONFIG_FAILED;
 	case BGP_ERR_PEER_GROUP_PEER_TYPE_DIFFERENT:
 		vty_out(vty,
-			"%% The AS# can not be changed from %u to %s, peer-group members must be all internal or all external\n",
+			"%% Peer-group members must be all internal or all external\n");
-			as, as_str);
 		return CMD_WARNING_CONFIG_FAILED;
 	}
 	return bgp_vty_return(vty, ret);
@@ -9212,8 +9210,8 @@ static void bgp_show_peer(struct vty *vty, struct peer *p, bool use_json,
 				? " replace-as"
 				: "");
 	}
-	/* peer type internal, external, confed-internal or confed-external */
+	/* peer type internal or confed-internal */
-	if (p->as == p->local_as) {
+	if ((p->as == p->local_as) || (p->as_type == AS_INTERNAL)) {
 		if (use_json) {
 			if (CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION))
 				json_object_boolean_true_add(
@@ -9227,7 +9225,8 @@ static void bgp_show_peer(struct vty *vty, struct peer *p, bool use_json,
 			else
 				vty_out(vty, "internal link\n");
 		}
-	} else {
+	/* peer type external or confed-external */
+	} else if (p->as || (p->as_type == AS_EXTERNAL)) {
 		if (use_json) {
 			if (CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION))
 				json_object_boolean_true_add(
@@ -9241,6 +9240,12 @@ static void bgp_show_peer(struct vty *vty, struct peer *p, bool use_json,
 			else
 				vty_out(vty, "external link\n");
 		}
+	} else {
+		if (use_json)
+			json_object_boolean_true_add(json_neigh,
+						     "nbrUnspecifiedLink");
+		else
+			vty_out(vty, "unspecified link\n");
 	}
 
 	/* Description. */

bgpd/bgpd.c

@@ -1001,7 +1001,26 @@ static inline bgp_peer_sort_t peer_calc_sort(struct peer *peer)
 
 		return BGP_PEER_EBGP;
 	} else {
-		if (peer->as_type != AS_SPECIFIED)
+		if (peer->as_type == AS_UNSPECIFIED) {
+			/* check if in peer-group with AS information */
+			if (peer->group
+			    && (peer->group->conf->as_type != AS_UNSPECIFIED)) {
+				if (peer->group->conf->as_type
+				    == AS_SPECIFIED) {
+					if (peer->local_as
+					    == peer->group->conf->as)
+						return BGP_PEER_IBGP;
+					else
+						return BGP_PEER_EBGP;
+				} else if (peer->group->conf->as_type
+					   == AS_INTERNAL)
+					return BGP_PEER_IBGP;
+				else
+					return BGP_PEER_EBGP;
+			}
+			/* no AS information anywhere, let caller know */
+			return BGP_PEER_UNSPECIFIED;
+		} else if (peer->as_type != AS_SPECIFIED)
 			return (peer->as_type == AS_INTERNAL ? BGP_PEER_IBGP
 							     : BGP_PEER_EBGP);
 
@@ -1711,20 +1730,32 @@ int peer_remote_as(struct bgp *bgp, union sockunion *su, const char *conf_if,
 
 		/* When this peer is a member of peer-group.  */
 		if (peer->group) {
-			if (peer->group->conf->as) {
+			/* peer-group already has AS number/internal/external */
+			if (peer->group->conf->as
+			    || peer->group->conf->as_type) {
 				/* Return peer group's AS number.  */
 				*as = peer->group->conf->as;
 				return BGP_ERR_PEER_GROUP_MEMBER;
 			}
-			if (peer_sort(peer->group->conf) == BGP_PEER_IBGP) {
+
-				if ((as_type != AS_INTERNAL)
+			bgp_peer_sort_t peer_sort_type =
-				    && (bgp->as != *as)) {
+						peer_sort(peer->group->conf);
+
+			/* Explicit AS numbers used, compare AS numbers */
+			if (as_type == AS_SPECIFIED) {
+				if (((peer_sort_type == BGP_PEER_IBGP)
+				    && (bgp->as != *as))
+				    || ((peer_sort_type == BGP_PEER_EBGP)
+				    && (bgp->as == *as))) {
 					*as = peer->as;
 					return BGP_ERR_PEER_GROUP_PEER_TYPE_DIFFERENT;
 				}
 			} else {
-				if ((as_type != AS_EXTERNAL)
+				/* internal/external used, compare as-types */
-				    && (bgp->as == *as)) {
+				if (((peer_sort_type == BGP_PEER_IBGP)
+				    && (as_type != AS_INTERNAL))
+				    || ((peer_sort_type == BGP_PEER_EBGP)
+				    && (as_type != AS_EXTERNAL)))  {
 					*as = peer->as;
 					return BGP_ERR_PEER_GROUP_PEER_TYPE_DIFFERENT;
 				}
@@ -2688,6 +2719,7 @@ int peer_group_bind(struct bgp *bgp, union sockunion *su, struct peer *peer,
 		if (peer->as_type == AS_UNSPECIFIED) {
 			peer->as_type = group->conf->as_type;
 			peer->as = group->conf->as;
+			peer->sort = group->conf->sort;
 		}
 
 		if (!group->conf->as) {

bgpd/bgpd.h

@@ -646,7 +646,8 @@ struct bgp_filter {
 /* IBGP/EBGP identifier.  We also have a CONFED peer, which is to say,
    a peer who's AS is part of our Confederation.  */
 typedef enum {
-	BGP_PEER_IBGP = 1,
+	BGP_PEER_UNSPECIFIED,
+	BGP_PEER_IBGP,
 	BGP_PEER_EBGP,
 	BGP_PEER_INTERNAL,
 	BGP_PEER_CONFED,