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-rw-r--r--proto/bgp/attrs.c88
1 files changed, 46 insertions, 42 deletions
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index 227ddadc..35aecdb0 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -41,24 +41,6 @@
* specifies that such updates should be ignored, but that is generally
* a bad idea.
*
- * Error checking of optional transitive attributes is done according to
- * draft-ietf-idr-optional-transitive-03, but errors are handled always
- * as withdraws.
- *
- * Unexpected AS_CONFED_* segments in AS_PATH are logged and removed,
- * but unknown segments cause a session drop with Malformed AS_PATH
- * error (see validate_path()). The behavior in such case is not
- * explicitly specified by RFC 4271. RFC 5065 specifies that
- * inconsistent AS_CONFED_* segments should cause a session drop, but
- * implementations that pass invalid AS_CONFED_* segments are
- * widespread.
- *
- * Error handling of AS4_* attributes is done as specified by
- * draft-ietf-idr-rfc4893bis-03. There are several possible
- * inconsistencies between AGGREGATOR and AS4_AGGREGATOR that are not
- * handled by that draft, these are logged and ignored (see
- * bgp_reconstruct_4b_attrs()).
- *
* BGP attribute table has several hooks:
*
* export - Hook that validates and normalizes attribute during export phase.
@@ -281,11 +263,19 @@ bgp_encode_as_path(struct bgp_write_state *s, eattr *a, byte *buf, uint size)
static void
bgp_decode_as_path(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
{
+ struct bgp_proto *p = s->proto;
+ int as_length = s->as4_session ? 4 : 2;
+ int as_confed = p->cf->confederation && p->is_interior;
char err[128];
- if (!as_path_valid(data, len, (s->as4_session ? 4 : 2), err, sizeof(err)))
+ if (!as_path_valid(data, len, as_length, as_confed, err, sizeof(err)))
WITHDRAW("Malformed AS_PATH attribute - %s", err);
+ /* In some circumstances check for initial AS_CONFED_SEQUENCE; RFC 5065 5.0 */
+ if (p->is_interior && !p->is_internal &&
+ ((len < 2) || (data[0] != AS_PATH_CONFED_SEQUENCE)))
+ WITHDRAW("Malformed AS_PATH attribute - %s", "missing initial AS_CONFED_SEQUENCE");
+
if (!s->as4_session)
{
/* Prepare 32-bit AS_PATH (from 16-bit one) in a temporary buffer */
@@ -603,11 +593,20 @@ bgp_decode_as4_path(struct bgp_parse_state *s, uint code UNUSED, uint flags, byt
if (len < 6)
DISCARD(BAD_LENGTH, "AS4_PATH", len);
- if (!as_path_valid(data, len, 4, err, sizeof(err)))
+ if (!as_path_valid(data, len, 4, 1, err, sizeof(err)))
DISCARD("Malformed AS4_PATH attribute - %s", err);
- /* XXXX remove CONFED segments */
- bgp_set_attr_data(to, s->pool, BA_AS4_PATH, flags, data, len);
+ struct adata *a = lp_alloc_adata(s->pool, len);
+ memcpy(a->data, data, len);
+
+ /* AS_CONFED* segments are invalid in AS4_PATH; RFC 6793 6 */
+ if (as_path_contains_confed(a))
+ {
+ REPORT("Discarding AS_CONFED* segment from AS4_PATH attribute");
+ a = as_path_strip_confed(s->pool, a);
+ }
+
+ bgp_set_attr_ptr(to, s->pool, BA_AS4_PATH, flags, a);
}
static void
@@ -1042,7 +1041,7 @@ bgp_decode_attrs(struct bgp_parse_state *s, byte *data, uint len)
if (bgp_as_path_loopy(p, attrs, p->local_as))
goto withdraw;
- /* Reject routes with our Confederation ID in AS_PATH attribute; RFC 5065 4 */
+ /* Reject routes with our Confederation ID in AS_PATH attribute; RFC 5065 4.0 */
if ((p->public_as != p->local_as) && bgp_as_path_loopy(p, attrs, p->public_as))
goto withdraw;
@@ -1322,15 +1321,7 @@ bgp_import_control(struct proto *P, rte **new, ea_list **attrs UNUSED, struct li
return 0;
}
-static const adata null_adata; /* adata of length 0 */
-
-static inline void
-bgp_path_prepend(ea_list **attrs, struct linpool *pool, int seg, u32 as, int strip)
-{
- eattr *a = bgp_find_attr(*attrs, BA_AS_PATH);
- adata *d = as_path_prepend2(pool, a ? a->u.ptr : &null_adata, seg, as, strip);
- bgp_set_attr_ptr(attrs, pool, BA_AS_PATH, 0, d);
-}
+static adata null_adata; /* adata of length 0 */
static inline void
bgp_cluster_list_prepend(ea_list **attrs, struct linpool *pool, u32 id)
@@ -1352,23 +1343,33 @@ bgp_update_attrs(struct bgp_proto *p, struct bgp_channel *c, rte *e, ea_list *at
if (! bgp_find_attr(attrs, BA_ORIGIN))
bgp_set_attr_u32(&attrs, pool, BA_ORIGIN, 0, src ? ORIGIN_INCOMPLETE : ORIGIN_IGP);
+ /* AS_PATH attribute */
+ a = bgp_find_attr(attrs, BA_AS_PATH);
+ adata *ad = a ? a->u.ptr : &null_adata;
+
+ /* AS_PATH attribute - strip AS_CONFED* segments outside confederation */
+ if ((!p->cf->confederation || !p->is_interior) && as_path_contains_confed(ad))
+ ad = as_path_strip_confed(pool, ad);
+
/* AS_PATH attribute - keep or prepend ASN */
if (p->is_internal ||
(p->rs_client && src && src->rs_client))
{
/* IBGP or route server -> just ensure there is one */
- if (! bgp_find_attr(attrs, BA_AS_PATH))
- bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, lp_alloc_adata(pool, 0));
+ if (!a)
+ bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, &null_adata);
}
else if (p->is_interior)
{
- /* Confederation -> prepend ASN as CONFED_SEQUENCE, keep CONFED_* segments */
- bgp_path_prepend(&attrs, pool, AS_PATH_CONFED_SEQUENCE, p->public_as, 0);
+ /* Confederation -> prepend ASN as AS_CONFED_SEQUENCE */
+ ad = as_path_prepend2(pool, ad, AS_PATH_CONFED_SEQUENCE, p->public_as);
+ bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, ad);
}
else /* Regular EBGP (no RS, no confederation) */
{
- /* Regular EBGP -> prepend ASN as regular segment, strip CONFED_* segments */
- bgp_path_prepend(&attrs, pool, AS_PATH_SEQUENCE, p->public_as, 1);
+ /* Regular EBGP -> prepend ASN as regular sequence */
+ ad = as_path_prepend2(pool, ad, AS_PATH_SEQUENCE, p->public_as);
+ bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, ad);
/* MULTI_EXIT_DESC attribute - accept only if set in export filter */
a = bgp_find_attr(attrs, BA_MULTI_EXIT_DISC);
@@ -1460,10 +1461,12 @@ bgp_get_neighbor(rte *r)
eattr *e = ea_find(r->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH));
u32 as;
- if (e && as_path_get_first(e->u.ptr, &as))
+ if (e && as_path_get_first_regular(e->u.ptr, &as))
return as;
- else
- return ((struct bgp_proto *) r->attrs->src->proto)->remote_as;
+
+ /* If AS_PATH is not defined, we treat rte as locally originated */
+ struct bgp_proto *p = (void *) r->attrs->src->proto;
+ return p->cf->confederation ?: p->local_as;
}
static inline int
@@ -1662,7 +1665,7 @@ bgp_rte_mergable(rte *pri, rte *sec)
}
/* RFC 4271 9.1.2.2. d) Prefer external peers */
- if (pri_bgp->is_internal != sec_bgp->is_internal)
+ if (pri_bgp->is_interior != sec_bgp->is_interior)
return 0;
/* RFC 4271 9.1.2.2. e) Compare IGP metrics */
@@ -1852,6 +1855,7 @@ bgp_process_as4_attrs(ea_list **attrs, struct linpool *pool)
/* Handle AS_PATH attribute */
if (p2 && p4)
{
+ /* Both as_path_getlen() and as_path_cut() take AS_CONFED* as zero length */
int p2_len = as_path_getlen(p2->u.ptr);
int p4_len = as_path_getlen(p4->u.ptr);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-24 05:04:07 +0000