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, 114 insertions, 0 deletions

diff --git a/zebra/zapi_msg.c b/zebra/zapi_msg.c
index 0a459b4d0a..e0c582779d 100644
--- a/zebra/zapi_msg.c
+++ b/zebra/zapi_msg.c
@@ -60,6 +60,7 @@
 #include "zebra/zebra_mlag.h"
 #include "zebra/connected.h"
 #include "zebra/zebra_opaque.h"
+#include "zebra/zebra_srte.h"
 
 /* Encoding helpers -------------------------------------------------------- */
 
@@ -1650,6 +1651,11 @@ static void zread_route_add(ZAPI_HANDLER_ARGS)
 			return;
 		}
 
+		if (CHECK_FLAG(api.message, ZAPI_MESSAGE_SRTE)) {
+			SET_FLAG(nexthop->flags, NEXTHOP_FLAG_SRTE);
+			nexthop->srte_color = api_nh->srte_color;
+		}
+
 		/* MPLS labels for BGP-LU or Segment Routing */
 		if (CHECK_FLAG(api_nh->flags, ZAPI_NEXTHOP_FLAG_LABEL)
 		    && api_nh->type != NEXTHOP_TYPE_IFINDEX
@@ -1729,6 +1735,11 @@ static void zread_route_add(ZAPI_HANDLER_ARGS)
 			nexthop->backup_num = 0;
 		}
 
+		if (CHECK_FLAG(api.message, ZAPI_MESSAGE_SRTE)) {
+			SET_FLAG(nexthop->flags, NEXTHOP_FLAG_SRTE);
+			nexthop->srte_color = api_nh->srte_color;
+		}
+
 		/* MPLS labels for BGP-LU or Segment Routing */
 		if (CHECK_FLAG(api_nh->flags, ZAPI_NEXTHOP_FLAG_LABEL)
 		    && api_nh->type != NEXTHOP_TYPE_IFINDEX
@@ -2180,6 +2191,107 @@ static void zread_mpls_labels_replace(ZAPI_HANDLER_ARGS)
 	mpls_zapi_labels_process(true, zvrf, &zl);
 }
 
+static void zread_sr_policy_set(ZAPI_HANDLER_ARGS)
+{
+	struct stream *s;
+	struct zapi_sr_policy zp;
+	struct zapi_srte_tunnel *zt;
+	struct zebra_sr_policy *policy;
+
+	/* Get input stream.  */
+	s = msg;
+	if (zapi_sr_policy_decode(s, &zp) < 0) {
+		if (IS_ZEBRA_DEBUG_RECV)
+			zlog_debug("%s: Unable to decode zapi_sr_policy sent",
+				   __PRETTY_FUNCTION__);
+		return;
+	}
+	zt = &zp.segment_list;
+	if (zt->label_num < 1) {
+		if (IS_ZEBRA_DEBUG_RECV)
+			zlog_debug(
+				"%s: SR-TE tunnel must contain at least one label",
+				__PRETTY_FUNCTION__);
+		return;
+	}
+
+	if (!mpls_enabled)
+		return;
+
+	policy = zebra_sr_policy_find(zp.color, &zp.endpoint);
+	if (!policy)
+		policy = zebra_sr_policy_add(zp.color, &zp.endpoint, zp.name);
+	/* TODO: per-VRF list of SR-TE policies. */
+	policy->zvrf = zvrf;
+
+	zebra_sr_policy_validate(policy, &zp.segment_list);
+}
+
+static void zread_sr_policy_delete(ZAPI_HANDLER_ARGS)
+{
+	struct stream *s;
+	struct zapi_sr_policy zp;
+	struct zebra_sr_policy *policy;
+
+	/* Get input stream.  */
+	s = msg;
+	if (zapi_sr_policy_decode(s, &zp) < 0) {
+		if (IS_ZEBRA_DEBUG_RECV)
+			zlog_debug("%s: Unable to decode zapi_sr_policy sent",
+				   __PRETTY_FUNCTION__);
+		return;
+	}
+
+	if (!mpls_enabled)
+		return;
+
+	policy = zebra_sr_policy_find(zp.color, &zp.endpoint);
+	if (!policy) {
+		if (IS_ZEBRA_DEBUG_RECV)
+			zlog_debug("%s: Unable to find SR-TE policy",
+				   __PRETTY_FUNCTION__);
+		return;
+	}
+
+	zebra_sr_policy_del(policy);
+}
+
+int zsend_sr_policy_notify_status(uint32_t color, struct ipaddr *endpoint,
+				  char *name, int status)
+{
+	struct zserv *client;
+	struct stream *s;
+
+	client = zserv_find_client(ZEBRA_ROUTE_SRTE, 0);
+	if (!client) {
+		if (IS_ZEBRA_DEBUG_PACKET)
+			zlog_debug(
+				"Not notifying pathd about policy %s"
+				" status change to %d",
+				name, status);
+		return 0;
+	}
+
+	if (IS_ZEBRA_DEBUG_PACKET)
+		zlog_debug(
+			"Notifying pathd about policy %s status change"
+			" to %d",
+			name, status);
+
+	s = stream_new(ZEBRA_MAX_PACKET_SIZ);
+	stream_reset(s);
+
+	zclient_create_header(s, ZEBRA_SR_POLICY_NOTIFY_STATUS, VRF_DEFAULT);
+	stream_putl(s, color);
+	stream_put_ipaddr(s, endpoint);
+	stream_write(s, name, SRTE_POLICY_NAME_MAX_LENGTH);
+	stream_putl(s, status);
+
+	stream_putw_at(s, 0, stream_get_endp(s));
+
+	return zserv_send_message(client, s);
+}
+
 /* Send response to a table manager connect request to client */
 static void zread_table_manager_connect(struct zserv *client,
 					struct stream *msg, vrf_id_t vrf_id)
@@ -2879,6 +2991,8 @@ void (*const zserv_handlers[])(ZAPI_HANDLER_ARGS) = {
 	[ZEBRA_BFD_CLIENT_REGISTER] = zebra_ptm_bfd_client_register,
 	[ZEBRA_INTERFACE_ENABLE_RADV] = zebra_interface_radv_enable,
 	[ZEBRA_INTERFACE_DISABLE_RADV] = zebra_interface_radv_disable,
+	[ZEBRA_SR_POLICY_SET] = zread_sr_policy_set,
+	[ZEBRA_SR_POLICY_DELETE] = zread_sr_policy_delete,
 	[ZEBRA_MPLS_LABELS_ADD] = zread_mpls_labels_add,
 	[ZEBRA_MPLS_LABELS_DELETE] = zread_mpls_labels_delete,
 	[ZEBRA_MPLS_LABELS_REPLACE] = zread_mpls_labels_replace,