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bgpd: Do not advertise aggregate routes to contributing ASes

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draft-ietf-idr-deprecate-as-set-confed-set-16 defines that we MUST NOT
advertise an aggregate prefix to the contributing ASes.

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
This commit is contained in:
Donatas Abraitis 2025-01-30 10:32:22 +02:00
parent de8f52b525
commit 925b365a87
3 changed files with 68 additions and 12 deletions
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42
bgpd/bgp_aspath.c
View file

@ -424,8 +424,12 @@ static unsigned int aspath_count_hops_internal(const struct aspath *aspath)
/* Check if aspath has AS_SET or AS_CONFED_SET */
bool aspath_check_as_sets(struct aspath *aspath)
{
struct assegment *seg = aspath->segments;
struct assegment *seg;
if (!aspath || !aspath->segments)
return false;
seg = aspath->segments;
while (seg) {
if (seg->type == AS_SET || seg->type == AS_CONFED_SET)
return true;
@ -2512,3 +2516,39 @@ void bgp_remove_aspath_from_aggregate_hash(struct bgp_aggregate *aggregate,
}
}
struct aspath *aspath_delete_as_set_seq(struct aspath *aspath)
{
struct assegment *seg, *prev, *next;
bool removed = false;
if (!(aspath && aspath->segments))
return aspath;
seg = aspath->segments;
next = NULL;
prev = NULL;
while (seg) {
next = seg->next;
if (seg->type == AS_SET || seg->type == AS_CONFED_SET) {
if (aspath->segments == seg)
aspath->segments = seg->next;
else
prev->next = seg->next;
assegment_free(seg);
removed = true;
} else
prev = seg;
seg = next;
}
if (removed) {
aspath_str_update(aspath, false);
aspath->count = aspath_count_hops_internal(aspath);
}
return aspath;
}

1
bgpd/bgp_aspath.h
View file

@ -168,5 +168,6 @@ extern void bgp_remove_aspath_from_aggregate_hash(
struct aspath *aspath);
extern void bgp_aggr_aspath_remove(void *arg);
extern struct aspath *aspath_delete_as_set_seq(struct aspath *aspath);
#endif /* _QUAGGA_BGP_ASPATH_H */

37
bgpd/bgp_route.c
View file

@ -2614,15 +2614,32 @@ bool subgroup_announce_check(struct bgp_dest *dest, struct bgp_path_info *pi,
bgp_peer_remove_private_as(bgp, afi, safi, peer, attr);
bgp_peer_as_override(bgp, afi, safi, peer, attr);
/* draft-ietf-idr-deprecate-as-set-confed-set
* Filter routes having AS_SET or AS_CONFED_SET in the path.
* Eventually, This document (if approved) updates RFC 4271
* and RFC 5065 by eliminating AS_SET and AS_CONFED_SET types,
* and obsoletes RFC 6472.
*/
if (peer->bgp->reject_as_sets)
if (aspath_check_as_sets(attr->aspath))
/* draft-ietf-idr-deprecate-as-set-confed-set-16 */
if (peer->bgp->reject_as_sets && aspath_check_as_sets(attr->aspath)) {
struct aspath *aspath_new;
/* An aggregate prefix MUST NOT be announced to the contributing ASes */
if (pi->sub_type == BGP_ROUTE_AGGREGATE &&
aspath_loop_check(attr->aspath, peer->as)) {
zlog_warn("%pBP [Update:SEND] %pFX is filtered by `bgp reject-as-sets`",
peer, p);
return false;
}
/* When aggregating prefixes, network operators MUST use consistent brief
* aggregation as described in Section 5.2. In consistent brief aggregation,
* the AGGREGATOR and ATOMIC_AGGREGATE Path Attributes are included, but the
* AS_PATH does not have AS_SET or AS_CONFED_SET path segment types.
* The ATOMIC_AGGREGATE Path Attribute is subsequently attached to the BGP
* route, if AS_SETs are dropped.
*/
if (attr->aspath->refcnt)
aspath_new = aspath_dup(attr->aspath);
else
aspath_new = attr->aspath;
attr->aspath = aspath_delete_as_set_seq(aspath_new);
}
/* If neighbor soo is configured, then check if the route has
* SoO extended community and validate against the configured
@ -8922,7 +8939,6 @@ static int bgp_aggregate_set(struct vty *vty, const char *prefix_str, afi_t afi,
struct prefix p;
struct bgp_dest *dest;
struct bgp_aggregate *aggregate;
uint8_t as_set_new = as_set;
if (suppress_map && summary_only) {
vty_out(vty,
@ -8980,7 +8996,6 @@ static int bgp_aggregate_set(struct vty *vty, const char *prefix_str, afi_t afi,
*/
if (bgp->reject_as_sets) {
if (as_set == AGGREGATE_AS_SET) {
as_set_new = AGGREGATE_AS_UNSET;
zlog_warn(
"%s: Ignoring as-set because `bgp reject-as-sets` is enabled.",
__func__);
@ -8989,7 +9004,7 @@ static int bgp_aggregate_set(struct vty *vty, const char *prefix_str, afi_t afi,
}
}
aggregate->as_set = as_set_new;
aggregate->as_set = as_set;
/* Override ORIGIN attribute if defined.
* E.g.: Cisco and Juniper set ORIGIN for aggregated address