lib, zebra: Add SR-TE policy infrastructure to zebra

For the sake of Segment Routing (SR) and Traffic Engineering (TE)
Policies there's a need for additional infrastructure within zebra.
The infrastructure in this PR is supposed to manage such policies
in terms of installing binding SIDs and LSPs. Also it is capable of
managing MPLS labels using the label manager, keeping track of
nexthops (for resolving labels) and notifying interested parties about
changes of a policy/LSP state. Further it enables a route map mechanism
for BGP and SR-TE colors such that learned BGP routes can be mapped
onto SR-TE Policies.

This PR does not introduce any usable features by now, it is just
infrastructure for other upcoming PRs which will introduce 'pathd',
a new SR-TE daemon.

Co-authored-by: Renato Westphal <renato@opensourcerouting.org>
Co-authored-by: GalaxyGorilla <sascha@netdef.org>
Signed-off-by: Sebastien Merle <sebastien@netdef.org>

1 files changed, 72 insertions, 11 deletions

diff --git a/zebra/zebra_nhg.c b/zebra/zebra_nhg.c
index 43bf745896..1c5b843539 100644
--- a/zebra/zebra_nhg.c
+++ b/zebra/zebra_nhg.c
@@ -28,6 +28,7 @@
 #include "lib/mpls.h"
 #include "lib/jhash.h"
 #include "lib/debug.h"
+#include "lib/lib_errors.h"
 
 #include "zebra/connected.h"
 #include "zebra/debug.h"
@@ -36,6 +37,7 @@
 #include "zebra/zebra_rnh.h"
 #include "zebra/zebra_routemap.h"
 #include "zebra/zebra_memory.h"
+#include "zebra/zebra_srte.h"
 #include "zebra/zserv.h"
 #include "zebra/rt.h"
 #include "zebra_errors.h"
@@ -1620,7 +1622,8 @@ void zebra_nhg_increment_ref(struct nhg_hash_entry *nhe)
 }
 
 static void nexthop_set_resolved(afi_t afi, const struct nexthop *newhop,
-				 struct nexthop *nexthop)
+				 struct nexthop *nexthop,
+				 struct zebra_sr_policy *policy)
 {
 	struct nexthop *resolved_hop;
 	uint8_t num_labels = 0;
@@ -1684,7 +1687,21 @@ static void nexthop_set_resolved(afi_t afi, const struct nexthop *newhop,
 		resolved_hop->flags |= NEXTHOP_FLAG_ONLINK;
 
 	/* Copy labels of the resolved route and the parent resolving to it */
-	if (newhop->nh_label) {
+	if (policy) {
+		int i = 0;
+
+		/*
+		 * Don't push the first SID if the corresponding action in the
+		 * LFIB is POP.
+		 */
+		if (!newhop->nh_label || !newhop->nh_label->num_labels
+		    || newhop->nh_label->label[0] == MPLS_LABEL_IMPLICIT_NULL)
+			i = 1;
+
+		for (; i < policy->segment_list.label_num; i++)
+			labels[num_labels++] = policy->segment_list.labels[i];
+		label_type = policy->segment_list.type;
+	} else if (newhop->nh_label) {
 		for (i = 0; i < newhop->nh_label->num_labels; i++) {
 			/* Be a bit picky about overrunning the local array */
 			if (num_labels >= MPLS_MAX_LABELS) {
@@ -1771,11 +1788,13 @@ static int nexthop_active(afi_t afi, struct route_entry *re,
 	struct route_node *rn;
 	struct route_entry *match = NULL;
 	int resolved;
+	zebra_nhlfe_t *nhlfe;
 	struct nexthop *newhop;
 	struct interface *ifp;
 	rib_dest_t *dest;
 	struct zebra_vrf *zvrf;
-	struct in_addr ipv4;
+	struct in_addr local_ipv4;
+	struct in_addr *ipv4;
 
 	if ((nexthop->type == NEXTHOP_TYPE_IPV4)
 	    || nexthop->type == NEXTHOP_TYPE_IPV6)
@@ -1839,6 +1858,51 @@ static int nexthop_active(afi_t afi, struct route_entry *re,
 	/* Validation for ipv4 mapped ipv6 nexthop. */
 	if (IS_MAPPED_IPV6(&nexthop->gate.ipv6)) {
 		afi = AFI_IP;
+		ipv4 = &local_ipv4;
+		ipv4_mapped_ipv6_to_ipv4(&nexthop->gate.ipv6, ipv4);
+	} else {
+		ipv4 = &nexthop->gate.ipv4;
+	}
+
+	if (nexthop->srte_color) {
+		struct ipaddr endpoint = {0};
+		struct zebra_sr_policy *policy;
+
+		switch (afi) {
+		case AFI_IP:
+			endpoint.ipa_type = IPADDR_V4;
+			endpoint.ipaddr_v4 = *ipv4;
+			break;
+		case AFI_IP6:
+			endpoint.ipa_type = IPADDR_V6;
+			endpoint.ipaddr_v6 = nexthop->gate.ipv6;
+			break;
+		default:
+			flog_err(EC_LIB_DEVELOPMENT,
+				 "%s: unknown address-family: %u", __func__,
+				 afi);
+			exit(1);
+		}
+
+		policy = zebra_sr_policy_find(nexthop->srte_color, &endpoint);
+		if (policy && policy->status == ZEBRA_SR_POLICY_UP) {
+			resolved = 0;
+			frr_each_safe (nhlfe_list, &policy->lsp->nhlfe_list,
+				       nhlfe) {
+				if (!CHECK_FLAG(nhlfe->flags,
+						NHLFE_FLAG_SELECTED)
+				    || CHECK_FLAG(nhlfe->flags,
+						  NHLFE_FLAG_DELETED))
+					continue;
+				SET_FLAG(nexthop->flags,
+					 NEXTHOP_FLAG_RECURSIVE);
+				nexthop_set_resolved(afi, nhlfe->nexthop,
+						     nexthop, policy);
+				resolved = 1;
+			}
+			if (resolved)
+				return 1;
+		}
 	}
 
 	/* Make lookup prefix. */
@@ -1847,12 +1911,7 @@ static int nexthop_active(afi_t afi, struct route_entry *re,
 	case AFI_IP:
 		p.family = AF_INET;
 		p.prefixlen = IPV4_MAX_PREFIXLEN;
-		if (IS_MAPPED_IPV6(&nexthop->gate.ipv6)) {
-			ipv4_mapped_ipv6_to_ipv4(&nexthop->gate.ipv6, &ipv4);
-			p.u.prefix4 = ipv4;
-		} else {
-			p.u.prefix4 = nexthop->gate.ipv4;
-		}
+		p.u.prefix4 = *ipv4;
 		break;
 	case AFI_IP6:
 		p.family = AF_INET6;
@@ -1978,7 +2037,8 @@ static int nexthop_active(afi_t afi, struct route_entry *re,
 
 				SET_FLAG(nexthop->flags,
 					 NEXTHOP_FLAG_RECURSIVE);
-				nexthop_set_resolved(afi, newhop, nexthop);
+				nexthop_set_resolved(afi, newhop, nexthop,
+						     NULL);
 				resolved = 1;
 			}
 
@@ -2001,7 +2061,8 @@ static int nexthop_active(afi_t afi, struct route_entry *re,
 
 				SET_FLAG(nexthop->flags,
 					 NEXTHOP_FLAG_RECURSIVE);
-				nexthop_set_resolved(afi, newhop, nexthop);
+				nexthop_set_resolved(afi, newhop, nexthop,
+						     NULL);
 				resolved = 1;
 			}
 done_with_match: