lib: Introducing a 3rd state for route-map match cmd: RMAP_NOOP

Introducing a 3rd state for route_map_apply library function: RMAP_NOOP

Traditionally route map MATCH rule apis  were designed to return
a binary response, consisting of either RMAP_MATCH or RMAP_NOMATCH.
(Route-map SET rule apis return RMAP_OKAY or RMAP_ERROR).
Depending on this response, the following statemachine decided the
course of action:

State1:
If match cmd returns RMAP_MATCH then, keep existing behaviour.
If routemap type is PERMIT, execute set cmds or call cmds if applicable,
otherwise PERMIT!
Else If routemap type is DENY, we DENYMATCH right away

State2:
If match cmd returns RMAP_NOMATCH, continue on to next route-map. If there
are no other rules or if all the rules return RMAP_NOMATCH, return DENYMATCH

We require a 3rd state because of the following situation:

The issue - what if, the rule api needs to abort or ignore a rule?:
"match evpn vni xx" route-map filter can be applied to incoming routes
regardless of whether the tunnel type is vxlan or mpls.
This rule should be N/A for mpls based evpn route, but applicable to only
vxlan based evpn route.
Also, this rule should be applicable for routes with VNI label only, and
not for routes without labels. For example, type 3 and type 4 EVPN routes
do not have labels, so, this match cmd should let them through.

Today, the filter produces either a match or nomatch response regardless of
whether it is mpls/vxlan, resulting in either permitting or denying the
route.. So an mpls evpn route may get filtered out incorrectly.
Eg: "route-map RM1 permit 10 ; match evpn vni 20" or
"route-map RM2 deny 20 ; match vni 20"

With the introduction of the 3rd state, we can abort this rule check safely.
How? The rules api can now return RMAP_NOOP to indicate
that it encountered an invalid check, and needs to abort just that rule,
but continue with other rules.

As a result we have a 3rd state:
State3:
If match cmd returned RMAP_NOOP
Then, proceed to other route-map, otherwise if there are no more
rules or if all the rules return RMAP_NOOP, then, return RMAP_PERMITMATCH.

Signed-off-by: Lakshman Krishnamoorthy <lkrishnamoor@vmware.com>

1 files changed, 19 insertions, 22 deletions

diff --git a/ripngd/ripng_routemap.c b/ripngd/ripng_routemap.c
index 0604e272c..d27ec76a5 100644
--- a/ripngd/ripng_routemap.c
+++ b/ripngd/ripng_routemap.c
@@ -38,10 +38,9 @@ struct rip_metric_modifier {
 
 /* `match metric METRIC' */
 /* Match function return 1 if match is success else return zero. */
-static route_map_result_t route_match_metric(void *rule,
-					     const struct prefix *prefix,
-					     route_map_object_t type,
-					     void *object)
+static enum route_map_cmd_result_t
+route_match_metric(void *rule, const struct prefix *prefix,
+		   route_map_object_t type, void *object)
 {
 	uint32_t *metric;
 	struct ripng_info *rinfo;
@@ -86,10 +85,9 @@ static struct route_map_rule_cmd route_match_metric_cmd = {
 
 /* `match interface IFNAME' */
 /* Match function return 1 if match is success else return zero. */
-static route_map_result_t route_match_interface(void *rule,
-						const struct prefix *prefix,
-						route_map_object_t type,
-						void *object)
+static enum route_map_cmd_result_t
+route_match_interface(void *rule, const struct prefix *prefix,
+		      route_map_object_t type, void *object)
 {
 	struct ripng_info *rinfo;
 	struct interface *ifp;
@@ -129,9 +127,10 @@ static struct route_map_rule_cmd route_match_interface_cmd = {
 
 /* `match tag TAG' */
 /* Match function return 1 if match is success else return zero. */
-static route_map_result_t route_match_tag(void *rule,
-					  const struct prefix *prefix,
-					  route_map_object_t type, void *object)
+static enum route_map_cmd_result_t route_match_tag(void *rule,
+						   const struct prefix *prefix,
+						   route_map_object_t type,
+						   void *object)
 {
 	route_tag_t *tag;
 	struct ripng_info *rinfo;
@@ -159,10 +158,9 @@ static struct route_map_rule_cmd route_match_tag_cmd = {
 /* `set metric METRIC' */
 
 /* Set metric to attribute. */
-static route_map_result_t route_set_metric(void *rule,
-					   const struct prefix *prefix,
-					   route_map_object_t type,
-					   void *object)
+static enum route_map_cmd_result_t
+route_set_metric(void *rule, const struct prefix *prefix,
+		 route_map_object_t type, void *object)
 {
 	if (type == RMAP_RIPNG) {
 		struct rip_metric_modifier *mod;
@@ -256,10 +254,9 @@ static struct route_map_rule_cmd route_set_metric_cmd = {
 /* `set ipv6 next-hop local IP_ADDRESS' */
 
 /* Set nexthop to object.  ojbect must be pointer to struct attr. */
-static route_map_result_t route_set_ipv6_nexthop_local(void *rule,
-						       const struct prefix *p,
-						       route_map_object_t type,
-						       void *object)
+static enum route_map_cmd_result_t
+route_set_ipv6_nexthop_local(void *rule, const struct prefix *p,
+			     route_map_object_t type, void *object)
 {
 	struct in6_addr *address;
 	struct ripng_info *rinfo;
@@ -310,9 +307,9 @@ static struct route_map_rule_cmd route_set_ipv6_nexthop_local_cmd = {
 /* `set tag TAG' */
 
 /* Set tag to object.  ojbect must be pointer to struct attr. */
-static route_map_result_t route_set_tag(void *rule,
-					const struct prefix *prefix,
-					route_map_object_t type, void *object)
+static enum route_map_cmd_result_t
+route_set_tag(void *rule, const struct prefix *prefix, route_map_object_t type,
+	      void *object)
 {
 	route_tag_t *tag;
 	struct ripng_info *rinfo;