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bgpd: add mpls vpn nh label bind cache struct and apis

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In the context of the ASBR facing an EBGP neighbor, or
facing an IBGP neighbor where the BGP updates received
are re-advertised with a modified next-hop, a new local
label will be re-advertised too, to replace the original
one.

Create a binding table, in the form of a hash list, from the
original labels to the new labels. Since labels can be the
same on several routers, set the next-hop and the label as
the keys. Add the needed API functions to manage the hash
list.

Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>
Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
This commit is contained in:
Louis Scalbert 2023-05-02 16:38:53 +02:00 committed by Philippe Guibert
parent 73e9ce89b9
commit 29b49f67eb
4 changed files with 125 additions and 0 deletions
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61
bgpd/bgp_mplsvpn.c
View File

@ -39,6 +39,9 @@
#include "bgpd/rfapi/rfapi_backend.h"
#endif
DEFINE_MTYPE_STATIC(BGPD, MPLSVPN_NH_LABEL_BIND_CACHE,
"BGP MPLSVPN nexthop label bind cache");
/*
* Definitions and external declarations.
*/
@ -3860,3 +3863,61 @@ void bgp_vpn_leak_export(struct bgp *from_bgp)
}
}
}
/* The nexthops values are compared to
* find in the tree the appropriate cache entry
*/
int bgp_mplsvpn_nh_label_bind_cmp(
const struct bgp_mplsvpn_nh_label_bind_cache *a,
const struct bgp_mplsvpn_nh_label_bind_cache *b)
{
if (prefix_cmp(&a->nexthop, &b->nexthop))
return 1;
if (a->orig_label > b->orig_label)
return 1;
if (a->orig_label < b->orig_label)
return -1;
return 0;
}
void bgp_mplsvpn_nh_label_bind_free(
struct bgp_mplsvpn_nh_label_bind_cache *bmnc)
{
if (bmnc->new_label != MPLS_INVALID_LABEL)
bgp_lp_release(LP_TYPE_BGP_L3VPN_BIND, bmnc, bmnc->new_label);
bgp_mplsvpn_nh_label_bind_cache_del(
&bmnc->bgp_vpn->mplsvpn_nh_label_bind, bmnc);
XFREE(MTYPE_MPLSVPN_NH_LABEL_BIND_CACHE, bmnc);
}
struct bgp_mplsvpn_nh_label_bind_cache *
bgp_mplsvpn_nh_label_bind_new(struct bgp_mplsvpn_nh_label_bind_cache_head *tree,
struct prefix *p, mpls_label_t orig_label)
{
struct bgp_mplsvpn_nh_label_bind_cache *bmnc;
bmnc = XCALLOC(MTYPE_MPLSVPN_NH_LABEL_BIND_CACHE,
sizeof(struct bgp_mplsvpn_nh_label_bind_cache));
bmnc->new_label = MPLS_INVALID_LABEL;
prefix_copy(&bmnc->nexthop, p);
bmnc->orig_label = orig_label;
LIST_INIT(&(bmnc->paths));
bgp_mplsvpn_nh_label_bind_cache_add(tree, bmnc);
return bmnc;
}
struct bgp_mplsvpn_nh_label_bind_cache *bgp_mplsvpn_nh_label_bind_find(
struct bgp_mplsvpn_nh_label_bind_cache_head *tree, struct prefix *p,
mpls_label_t orig_label)
{
struct bgp_mplsvpn_nh_label_bind_cache bmnc = {0};
if (!tree)
return NULL;
prefix_copy(&bmnc.nexthop, p);
bmnc.orig_label = orig_label;
return bgp_mplsvpn_nh_label_bind_cache_find(tree, &bmnc);
}

56
bgpd/bgp_mplsvpn.h
View File

@ -325,4 +325,60 @@ extern void vpn_handle_router_id_update(struct bgp *bgp, bool withdraw,
extern void bgp_vpn_leak_unimport(struct bgp *from_bgp);
extern void bgp_vpn_leak_export(struct bgp *from_bgp);
extern int
bgp_mplsvpn_nh_label_bind_cmp(const struct bgp_mplsvpn_nh_label_bind_cache *a,
const struct bgp_mplsvpn_nh_label_bind_cache *b);
/* used to bind a local label to the (label, nexthop) values
* from an incoming BGP mplsvpn update
*/
struct bgp_mplsvpn_nh_label_bind_cache {
/* RB-tree entry. */
struct bgp_mplsvpn_nh_label_bind_cache_item entry;
/* The nexthop and the vpn label are the key of the list.
* Only received BGP MPLSVPN updates may use that structure.
* orig_label is the original label received from the BGP Update.
*/
struct prefix nexthop;
mpls_label_t orig_label;
/* number of mplsvpn path */
unsigned int path_count;
/* back pointer to bgp instance */
struct bgp *bgp_vpn;
/* MPLS label allocated value.
* When the next-hop is changed because of 'next-hop-self' or
* because it is an eBGP peer, the redistributed orig_label value
* is unmodified, unless the 'l3vpn-multi-domain-switching'
* is enabled: a new_label value is allocated:
* - The new_label value is sent in the advertised BGP update,
* instead of the label value.
* - An MPLS entry is set to swap <new_label> with <orig_label>.
*/
mpls_label_t new_label;
/* list of path_vrfs using it */
LIST_HEAD(mplsvpn_nh_label_bind_path_lists, bgp_path_info) paths;
time_t last_update;
};
DECLARE_RBTREE_UNIQ(bgp_mplsvpn_nh_label_bind_cache,
struct bgp_mplsvpn_nh_label_bind_cache, entry,
bgp_mplsvpn_nh_label_bind_cmp);
void bgp_mplsvpn_nh_label_bind_free(
struct bgp_mplsvpn_nh_label_bind_cache *bmnc);
struct bgp_mplsvpn_nh_label_bind_cache *
bgp_mplsvpn_nh_label_bind_new(struct bgp_mplsvpn_nh_label_bind_cache_head *tree,
struct prefix *p, mpls_label_t orig_label);
struct bgp_mplsvpn_nh_label_bind_cache *bgp_mplsvpn_nh_label_bind_find(
struct bgp_mplsvpn_nh_label_bind_cache_head *tree, struct prefix *p,
mpls_label_t orig_label);
#endif /* _QUAGGA_BGP_MPLSVPN_H */

2
bgpd/bgpd.c
View File

@ -3361,6 +3361,8 @@ static struct bgp *bgp_create(as_t *as, const char *name,
bgp_label_per_nexthop_cache_init(
&bgp->mpls_labels_per_nexthop[afi]);
bgp_mplsvpn_nh_label_bind_cache_init(&bgp->mplsvpn_nh_label_bind);
if (name)
bgp->name = XSTRDUP(MTYPE_BGP, name);

6
bgpd/bgpd.h
View File

@ -331,6 +331,9 @@ struct as_confed {
char *as_pretty;
};
struct bgp_mplsvpn_nh_label_bind_cache;
PREDECL_RBTREE_UNIQ(bgp_mplsvpn_nh_label_bind_cache);
/* BGP instance structure. */
struct bgp {
/* AS number of this BGP instance. */
@ -578,6 +581,9 @@ struct bgp {
struct bgp_label_per_nexthop_cache_head
mpls_labels_per_nexthop[AFI_MAX];
/* Tree for mplsvpn next-hop label bind cache */
struct bgp_mplsvpn_nh_label_bind_cache_head mplsvpn_nh_label_bind;
/* Allocate hash entries to store policy routing information
* The hash are used to host pbr rules somewhere.
* Actually, pbr will only be used by flowspec